Note: Descriptions are shown in the official language in which they were submitted.
1
AGGREGATE RADIATED POWER CONTROL FOR MULTI-BAND/MULTI-
MODE SATELLITE RADIOTELEPHONE COMMUNICATIONS SYSTEMS AND
METHODS
Field of the Invention
This invention relates to radiotelephone communications systems and methods,
and
more particularly to terrestrial cellular and satellite cellular
radiotelephone communications
systems and methods.
Background of the Invention
Satellite radiotelephone communications systems and methods are widely used
for
radiotelephone communications. Satellite radiotelephone communications systems
and
methods generally employ at least one space-based component, such as one or
more satellites
that are configured to wirelessly communicate with a plurality of satellite
radiotelephones.
A satellite radiotelephone communications system or method may utilize a
single
antenna beam covering an entire area served by the system. Alternatively, in
cellular satellite
radiotelephone communications systems and methods, multiple beams are
provided, each of
which can serve distinct geographical areas in the overall service region, to
collectively
serve an overall satellite footprint. Thus, a cellular architecture similar to
that used in
conventional terrestrial cellular radiotelephone systems and methods can be
implemented in
cellular satellite-based systems and methods. The satellite typically
communicates with
radiotelephones over a bidirectional communications pathway, with
radiotelephone
communication signals being communicated from the satellite to the
radiotelephone over a
CA 2989660 2017-12-19 ---
2
downlink or forward link, and from the radiotelephone to the satellite over an
uplink or return
link.
The overall design and operation of cellular satellite radiotelephone systems
and
methods are well known to those having skill in the art, and need not be
described further
herein. Moreover, as used herein, the term "radiotelephone" includes cellular
and/or satellite
radiotelephones with or without a multi-line display; Personal Communications
System
(PCS) terminals that may combine a radiotelephone with data processing,
facsimile and/or
data communications capabilities; Personal Digital Assistants (PDA) that can
include a radio
frequency transceiver and a pager, Internet/intranet access, Web browser,
organizer, calendar
and/or a global positioning system (GPS) receiver; and/or conventional laptop
and/or palmtop
computers or other appliances, which include a radio frequency transceiver. A
radiotelephone also may be referred to herein as a radioterminal.
Terrestrial networks can enhance cellular satellite radiotelephone system
availability,
efficiency and/or economic viability by terrestrially reusing at least some of
the frequency
bands that are allocated to cellular satellite radiotelephone systems. In
particular, it is known
that it may be difficult for cellular satellite radiotelephone systems to
reliably serve densely
populated areas, because the satellite signal may be blocked by high-rise
structures and/or
may not penetrate into buildings. As a result, the satellite spectrum may be
underutilized or
unutilized in such areas. The terrestrial reuse of at least some of a
satellite band's frequencies
can reduce or eliminate this potential problem.
Moreover, the capacity of the overall system can be increased significantly by
the
introduction of terrestrial reuse of a satellite band's frequencies, since
terrestrial frequency
reuse can be much denser than that of a satellite-only system. In fact,
capacity can be
enhanced where it may be mostly needed, i.e., densely populated
urban/industrial/commercial
areas. As a result, the overall system can become much more economically
viable, as it may
be able to serve a much larger subscriber base.
One example of terrestrial reuse of satellite frequencies is described in U.
S. Patent
5,937, 332 to the present inventor Karabinis entitled Satellite
Telecommunications Repeaters
and Retransmission Methods. As described therein, satellite telecommunications
repeaters
are provided which receive, amplify, and locally retransmit the downlink
signal received
from a satellite thereby increasing the effective downlink margin in the
vicinity of the
satellite telecommunications repeaters and allowing an increase in the
penetration of uplink
and downlink signals into buildings, foliage, transportation vehicles,
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WO 2004/100501 PCT/US2004/012541
3
and other objects which can reduce link margin. Both portable and non-portable
repeaters are
provided. See the abstract of U.S. Patent 5,937,332.
Finally, satellite radiotelephones for a satellite radiotelephone system or
method
having a terrestrial component within the same satellite frequency band and
using
substantially the same air interface for both terrestrial and satellite
communications can be
cost effective and/or aesthetically appealing. Conventional dual band/dual
mode alternatives,
such as the well known Thuraya, Iridium and/or Globalstar dual mode
satellite/terrestrial
radiotelephone systems, may duplicate some components, which may lead to
increased cost,
size and/or weight of the radiotelephone. See U.S. Patent 6,052,560 to the
present inventor
Karabinis, entitled Satellite System Utilizing a Plurality of Air Interface
Standards and
Method Employing Same.
In view of the above discussion, there continues to be a need for systems and
methods
for terrestrial reuse of cellular satellite frequencies that can allow
improved reliability,
capacity, cost effectiveness and/or aesthetic appeal for cellular satellite
radiotelephone
systems, methods and/or satellite radiotelephones.
Summary of the Invention
Some embodiments of the present invention provide satellite radiotelephone
systems
and communications methods wherein a space-based component is configured to
communicate with radiotelephones in a satellite footprint that is divided into
a plurality of
satellite cells. The space-based component is configured to communicate with a
first
radiotelephone in a first satellite cell over a first frequency band and/or a
first air interface,
and to communicate with a second radiotelephone in a second satellite cell
over a second
frequency band and/or a second air interface. In some embodiments, an
ancillary terrestrial
network also is provided that is configured to communicate terrestrially with
the first
radiotelephone over substantially the first frequency band and/or
substantially the first air
interface, and to communicate terrestrially with the second radiotelephone
over substantially
the second frequency band and/or substantially the second air interface.
In other embodiments, satellite radiotelephone systems and methods comprise a
space-based component that is configured to communicate with a first
radiotelephone over a
first frequency band and/or a first air interface, and with a second
radiotelephone over a
second frequency band and/or a second air interface. An ancillary terrestrial
network is
configured to communicate terrestrially with the first radiotelephone over
substantially the
first frequency band and/or substantially the first air interface, and to
communicate
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WO 2004/1005()1 PCT/US2004/012541
4
terrestrially with the second radiotelephone over substantially the second
frequency band
and/or substantially the second air interface. The first and second
radiotelephones may be in
the same satellite cell or in different satellite cells.
In any of the above embodiments, the ancillary terrestrial network can
comprise a first
ancillary terrestrial component that is configured to communicate
terrestrially with the first
radiotelephone over substantially the first frequency band and/or
substantially the first air
interface, and a second ancillary terrestrial component that is configured to
communicate
terrestrially with the second and/or first radiotelephone over substantially
the second
frequency band and/or substantially the second air interface. In some
embodiments, the first
ancillary terrestrial component is in the first satellite cell, and the second
ancillary terrestrial
component is in the second satellite cell. In other embodiments, they are in
the same satellite
cell. In yet other embodiments, the first ancillary terrestrial component is
operated by a first
wireless network operator and the second ancillary terrestrial component is
operated by a
second wireless network operator.
Moreover, in any of the above-described embodiments, the ancillary terrestrial
network can comprise a first portion that is configured to communicate
terrestrially with the
first radiotelephone over substantially the first frequency band and/or
substantially the first
air interface, and a second portion that is configured to communicate
terrestrially with the
second and/or first radiotelephone over substantially the second frequency
band and/or
substantially the second air interface. In some embodiments, the first portion
is operated by a
first wireless network operator and the second portion is operated by a second
wireless
network operator.
In any of the above embodiments, a gateway also may be provided that is
configured
to communicate with the space-based component over a feeder link. The feeder
link is
configured to transport communications between the space-based component and
the first and
second radiotelephones. In some embodiments, the feeder link comprises the
first air
interface and the second air interface.
Still other embodiments of the present invention control the aggregate
radiated power
by the radiotelephones in multi-band/multi-mode satellite radiotelephone
communications
systems and methods. Specifically, some embodiments of the present invention
provide
satellite radiotelephone systems wherein a space-based component is configured
to
communicate with a plurality of radiotelephones over a plurality of frequency
bands and/or a
plurality of air interfaces. An ancillary terrestrial network is configured to
communicate
terrestrially with the plurality of radiotelephones over substantially the
plurality of first
CA 2989660 2017-12-19
5
frequency bands and/or substantially the plurality of air interfaces. An
aggregate radiated
power controller is configured to limit an aggregate radiated power by the
plurality of
radiotelephones to a maximum aggregate radiated power. Analogous aggregate
radiated power
controlling methods also may be provided.
Accordingly, some embodiments of the present invention allow space-based
communications to be added to a first terrestrial network that is configured
to communicate
with a first radiotelephone over a first frequency band and/or a first air
interface, and to a
second terrestrial network that is configured to communicate with a second
radiotelephone
over a second frequency band and/or a second air interface. These embodiments
provide
communications between a space-based component and the first radiotelephone
over
substantially the first frequency band and/or the first air interface and
between the space-
based component and the second radiotelephone over substantially the second
frequency
band and/or substantially the second air interface. It will be understood that
embodiments of
the present invention may be provided as systems and/or methods.
According to an aspect, there is provided a satellite radiotelephone system
comprising: a space-based component that is configured to communicate with a
plurality of
radiotelephones over a plurality of frequency bands and/or a plurality of air
interfaces; an
ancillary terrestrial network that is configured to communicate terrestrially
with the plurality
of radiotelephones over substantially the plurality of frequency bands and/or
substantially the
plurality of air interfaces; and an aggregate radiated power controller that
is configured to
control the plurality of radiotelephones and/or the ancillary terrestrial
network so as to limit
an aggregate radiated power by the plurality of radiotelephones to a maximum
aggregate
radiated power; wherein the plurality of frequency bands and/or the plurality
of air interfaces
comprise a GSM air interface and a CDMA air interface and wherein the
aggregate radiated
power controller is configured to control the plurality of radiotelephones
and/or the ancillary
terrestrial network, so as to limit the aggregate radiated power by the
plurality of
radiotelephones to a maximum aggregate radiated power substantially according
to the
following: NGsm+13,800NcbmA/107,894=13,800; where NGSM denotes a number of co-
frequency time slots that are using the GSM air interface and NCDMA denotes a
number of co-
frequency codes that are using the CDMA air interface.
According to another aspect, there is provided a satellite radiotelephone
system
comprising: a space-based component that is configured to communicate with a
plurality of
radiotelephones over a plurality of frequency bands and/or a plurality of air
interfaces; an
CA 2989660 2017-12-19
5a
ancillary terrestrial network that is configured to communicate terrestrially
with the plurality
of radiotelephones over substantially the plurality of frequency bands and/or
substantially the
plurality of air interfaces; and an aggregate radiated power controller that
is configured to
control the plurality of radiotelephones and/or the ancillary terrestrial
network so as to limit
an aggregate radiated power by the plurality of radiotelephones to a maximum
aggregate
radiated power; wherein the plurality of frequency bands and/or the plurality
of air interfaces
comprise a GSM air interface, a cdma2000 air interface and/or a W-CDMA air
interface and
wherein the aggregate radiated power controller is configured to control the
plurality of
radiotelephones and/or the ancillary terrestrial network, so as to limit the
aggregate radiated
power by the plurality of radiotelephones to a maximum aggregate radiated
power
substantially according to the following: N/8+M/50+L/200=R; where N denotes a
number of
co-frequency time slots that are using the GSM air interface, M denotes a
number of co-
frequency codes that are using the cdma2000 air interface, L denotes a number
of co-
frequency codes that are using the W-CDMA air interface and R denotes an
authorized GSM-
based frequency reuse.
According to another aspect, there is provided a satellite radiotelephone
system
comprising: a space-based component that is configured to communicate with a
plurality of
radiotelephones over a plurality of frequency bands and/or a plurality of air
interfaces; an
ancillary terrestrial network that is configured to communicate terrestrially
with the plurality
of radiotelephones over substantially the plurality of frequency bands and/or
substantially the
plurality of air interfaces; and an aggregate radiated power controller that
is configured to
control the plurality of radiotelephones and/or the ancillary terrestrial
network so as to limit
an aggregate radiated power by the plurality of radiotelephones to a maximum
aggregate
radiated power; wherein the aggregate radiated power controller is configured
to control the
plurality of radiotelephones and/or the ancillary terrestrial network, so as
to limit the
aggregate radiated power by the plurality of radiotelephones to a maximum
aggregate
radiated power according to the following:
x N.
MARP
where N, denotes a number of co-frequency channels that are using a given
frequency band
and/or air interface i, F, denotes a corresponding equivalence factor, which
may be less than,
CA 2989660 2017-12-19
5b
greater than or equal to 1, for the given frequency band/air interface i, and
MARP is a
measure of the maximum aggregate radiated power.
According to another aspect of the present invention, there is provided a
satellite
radiotelephone system comprising: a space-based component that is configured
to
communicate with a plurality of radiotelephones over a plurality of frequency
bands and/or a
plurality of air interfaces; an ancillary terrestrial network that is
configured to communicate
terrestrially with the plurality of radiotelephones over substantially the
plurality of frequency
bands and/or substantially the plurality of air interfaces; and an aggregate
radiated power
controller that is configured to control the plurality of radiotelephones
and/or the ancillary
terrestrial network so as to limit an aggregate radiated power by the
plurality of
radiotelephones to a maximum aggregate radiated power; wherein the aggregate
radiated
power controller is configured to control the plurality of radiotelephones
and/or the ancillary
terrestrial network, so as to limit the aggregate radiated power by the
plurality of
radiotelephones to a maximum aggregate radiated power according to the
following:
x N.
MARP
where N, denotes a number of co-frequency channels that are using a given
structural
attenuation margin i for a given frequency band and/or air interface, F,
denotes a
corresponding equivalence factor, which may be less than, greater than or
equal to 1, for the
given structural attenuation margin i for the given frequency band/air
interface, and MARP is
a measure of the maximum aggregate radiated power.
According to another aspect, there is provided a satellite radiotelephone
system
comprising: a space-based component that is configured to communicate with a
plurality of
radiotelephones over a plurality of frequency bands and/or a plurality of air
interfaces; an
ancillary terrestrial network that is configured to communicate terrestrially
with the plurality
of radiotelephones over substantially the plurality of frequency bands and/or
substantially the
plurality of air interfaces; and an aggregate radiated power controller that
is configured to
control the plurality of radiotelephones and/or the ancillary terrestrial
network so as to limit
an aggregate radiated power by the plurality of radiotelephones to a maximum
aggregate
radiated power; wherein the aggregate radiated power controller is configured
to control the
plurality of radiotelephones and/or the ancillary terrestrial network, so as
to limit the
aggregate radiated power by a plurality of co-frequency radiotelephones to a
maximum
CA 2989660 2017-12-19
5c
aggregate radiated power according to the following:
= MARP ;
where (psd), denotes a measure of radiated power spectral density from an ith
radiotelephone
at a satellite and MARP is a measure of the allowed maximum aggregate radiated
power.
According to another aspect, there is provided a satellite radiotelephone
communications method comprising: communicating between a space-based
component and
a plurality of radiotelephones over a plurality of frequency bands and/or a
plurality of air
interfaces; communicating terrestrially with the plurality of radiotelephones
over
substantially the plurality of frequency bands and/or substantially the
plurality of air
interfaces; and controlling the plurality of radiotelephones and/or the
ancillary terrestrial
network so as to limit an aggregate radiated power by the plurality of
radiotelephones to a
maximum aggregate radiated power; wherein the plurality of frequency bands
and/or the
plurality of air interfaces comprise a GSM air interface and a CDMA air
interface and
wherein controlling the plurality of radiotelephones and/or the ancillary
terrestrial network so
as to limit the aggregate radiated power by the plurality of radiotelephones
to a maximum
aggregate radiated power comprises controlling the plurality of
radiotelephones substantially
according to the following: NGSM+13,800NcDmA/107,894=13,800; where NGSM
denotes a
number of co-frequency time slots that are using the GSM air interface and
NcDmA denotes a
number of co-frequency codes that are using the CDMA air interface.
According to another aspect, there is provided a satellite radiotelephone
communications method comprising: communicating between a space-based
component and
a plurality of radiotelephones over a plurality of frequency bands and/or a
plurality of air
interfaces; communicating terrestrially with the plurality of radiotelephones
over
substantially the plurality of frequency bands and/or substantially the
plurality of air
interfaces; and controlling the plurality of radiotelephones and/or the
ancillary terrestrial
network so as to limit an aggregate radiated power by the plurality of
radiotelephones to a
maximum aggregate radiated power; wherein the plurality of frequency bands
and/or a
plurality of air interfaces comprise a GSM air interface, a cdma2000 air
interface and/or a W-
CDMA air interface and wherein controlling the plurality of radiotelephones
and/or the
ancillary terrestrial network, so as to limit the aggregate radiated power by
the plurality of
radiotelephones to a maximum aggregate radiated power comprises controlling
the plurality
of radiotelephones substantially according to the following:
N/80+M/50+L/200+R; where N
CA 2989660 2017-12-19
5d
denotes a number of co-frequency time slots that are using the GSM air
interface, M denotes
a number of co-frequency codes that are using the cdma2000 air interface, L
denotes a
number of co-frequency codes that are using the W-CDMA air interface, and R
denotes an
authorized GSM-based frequency reuse.
According to another aspect, there is provided a satellite radiotelephone
communications method comprising: communicating between a space-based
component and
a plurality of radiotelephones over a plurality of frequency bands and/or a
plurality of air
interfaces; communicating terrestrially with the plurality of radiotelephones
over
substantially the plurality of frequency bands and/or substantially the
plurality of air
interfaces; and controlling the plurality of radiotelephones and/or the
ancillary terrestrial
network so as to limit an aggregate radiated power by the plurality of
radiotelephones to a
maximum aggregate radiated power; wherein controlling the plurality of
radiotelephones
and/or the ancillary terrestrial network, so as to limit the aggregate
radiated power by the
plurality of radiotelephones to a maximum aggregate radiated power is
performed according
to the following:
N.
where N, denotes a number of co-frequency channels that are using a given
frequency band
and/or air interface i, F, denotes a corresponding equivalence factor, which
may be less than,
greater than or equal to 1, for the given frequency band/air interface i, and
MARP is a
measure of the maximum aggregate radiated power.
According to another aspect, there is provided a satellite radiotelephone
communications method comprising: communicating between a space-based
component and
a plurality of radiotelephones over a plurality of frequency bands and/or a
plurality of air
interfaces; communicating terrestrially with the plurality of radiotelephones
over
substantially the plurality of frequency bands and/or substantially the
plurality of air
interfaces; and controlling the plurality of radiotelephones and/or the
ancillary terrestrial
network so as to limit an aggregate radiated power by the plurality of
radiotelephones to a
maximum aggregate radiated power; wherein controlling the plurality of
radiotelephones
and/or the ancillary terrestrial network so as to limit the aggregate radiated
power by the
plurality of radiotelephones to a maximum aggregate radiated power is
performed according
to the following:
CA 2989660 2017-12-19
5e
x N.
MARP;
where N, denotes a number of co-frequency channels that are using a given
structural
attenuation margin i for a given frequency band and/or air interface, F,
denotes a
corresponding equivalence factor, which may be less than, greater than or
equal to 1, for the
given structural attenuation margin i for the given frequency band/air
interface, and MARP is
a measure of the maximum aggregate radiated power.
According to another aspect, there is provided a satellite radiotelephone
communications method comprising: communicating between a space-based
component and
a plurality of radiotelephones over a plurality of frequency bands and/or a
plurality of air
interfaces; communicating terrestrially with the plurality of radiotelephones
over
substantially the plurality of frequency bands and/or substantially the
plurality of air
interfaces; and controlling the plurality of radiotelephones and/or the
ancillary terrestrial
network so as to limit an aggregate radiated power by the plurality of
radiotelephones to a
maximum aggregate radiated power; wherein controlling the plurality of
radiotelephones
and/or the ancillary terrestrial network, so as to limit the aggregate
radiated power by a
plurality of co-frequency radiotelephones to a maximum aggregate radiated
power is
performed according to the following:
E (psci); = MARP ;
where (psd), denotes a measure of radiated power spectral density from an ith
radiotelephone
at a satellite and MARP is a measure of the allowed maximum aggregate radiated
power.
According to another aspect, there is provided an apparatus for controlling a
satellite
radiotelephone system that comprises a space-based component that is
configured to
communicate with a plurality of radiotelephones over a plurality of frequency
bands and/or a
plurality of air interfaces and an ancillary terrestrial network that is
configured to
communicate terrestrially with the plurality of radiotelephones over
substantially the plurality
of frequency bands and/or substantially the plurality of air interfaces, the
apparatus
comprising: an aggregate radiated power controller that is configured to
control the plurality
of radiotelephones and/or the ancillary terrestrial network so as to limit the
aggregate radiated
power by the plurality of radiotelephones to a maximum aggregate radiated
power; wherein
the plurality of frequency bands and/or the plurality of air interfaces
comprise a GSM air
CA 2989660 2017-12-19
5f
interface and a CDMA air interface and wherein the aggregate radiated power
controller is
configured to control the plurality of radiotelephones and/or the ancillary
terrestrial network,
so as to limit the aggregate radiated power by the plurality of
radiotelephones to a maximum
aggregate radiated power substantially according to the following:
NGsm+13,800NcDmA/107,894=13,800; where NGSm denotes a number of co-frequency
time
slots that are using the GSM air interface and NCDMA denotes a number of co-
frequency codes
that are using the CDMA air interface.
According to another aspect, there is provided an apparatus for controlling a
satellite
radiotelephone system that comprises a space-based component that is
configured to
communicate with a plurality of radiotelephones over a plurality of frequency
bands and/or a
plurality of air interfaces and an ancillary terrestrial network that is
configured to
communicate terrestrially with the plurality of radiotelephones over
substantially the plurality
of frequency bands and/or substantially the plurality of air interfaces, the
apparatus
comprising: an aggregate radiated power controller that is configured to
control the plurality
of radiotelephones and/or the ancillary terrestrial network so as to limit the
aggregate radiated
power by the plurality of radiotelephones to a maximum aggregate radiated
power; wherein
the plurality of frequency bands and/or the plurality of air interfaces
comprise a GSM air
interface, a cdma2000 air interface and/or a W-CDMA air interface and wherein
the
aggregate radiated power controller is configured to control the plurality of
radiotelephones
and/or the ancillary terrestrial network, so as to limit the aggregate
radiated power by the
plurality of radiotelephones to a maximum aggregate radiated power
substantially according
to the following: N/8+M/50+L/200=R; where N denotes a number of co-frequency
time slots
that are using the GSM air interface, M denotes a number of co-frequency codes
that are
using the cdma2000 air interface, L denotes a number of co-frequency codes
that are using
the W-CDMA air interface, and R denotes an authorized GSM-based frequency
reuse.
According to another aspect, there is provided an apparatus for controlling a
satellite
radiotelephone system that comprises a space-based component that is
configured to
communicate with a plurality of radiotelephones over a plurality of frequency
bands and/or a
plurality of air interfaces and an ancillary terrestrial network that is
configured to
communicate terrestrially with the plurality of radiotelephones over
substantially the plurality
of frequency bands and/or substantially the plurality of air interfaces, the
apparatus
comprising: an aggregate radiated power controller that is configured to
control the plurality
of radiotelephones and/or the ancillary terrestrial network so as to limit the
aggregate radiated
CA 2989660 2017-12-19
5g
power by the plurality of radiotelephones to a maximum aggregate radiated
power; wherein
the aggregate radiated power controller is configured to control the plurality
of
radiotelephones and/or the ancillary terrestrial network, so as to limit the
aggregate radiated
power by the plurality of radiotelephones to a maximum aggregate radiated
power according
to the following:
= MARP ;
where N, denotes a number of co-frequency channels that are using a given
frequency band
and/or air interface i, F, denotes a corresponding equivalence factor, which
may be less than,
greater than or equal to 1, for the given frequency band/air interface i, and
MARP is a
measure of the maximum aggregate radiated power.
According to another aspect, there is provided an apparatus for controlling a
satellite
radiotelephone system that comprises a space-based component that is
configured to
communicate with a plurality of radiotelephones over a plurality of frequency
bands and/or a
plurality of air interfaces and an ancillary terrestrial network that is
configured to
communicate terrestrially with the plurality of radiotelephones over
substantially the plurality
of frequency bands and/or substantially the plurality of air interfaces, the
apparatus
comprising: an aggregate radiated power controller that is configured to
control the plurality
of radiotelephones and/or the ancillary terrestrial network so as to limit the
aggregate radiated
power by the plurality of radiotelephones to a maximum aggregate radiated
power; wherein
the aggregate radiated power controller is configured to control the plurality
of
radiotelephones and/or the ancillary terrestrial network so as to limit the
aggregate radiated
power by the plurality of radiotelephones to a maximum aggregate radiated
power according
to the following:
Ni
MARP ;
6,1
where Ni denotes a number of co-frequency channels that are using a given
structural
attenuation margin i for a given frequency band and/or air interface, F,
denotes a
corresponding equivalence factor, which may be less than, greater than or
equal to 1, for the
given structural attenuation margin i for the given frequency band/air
interface, and MARP is
a measure of the maximum aggregate radiated power.
CA 2989660 2017-12-19
5h
According to another aspect, there is provided an apparatus for controlling a
satellite
radiotelephone system that comprises a space-based component that is
configured to
communicate with a plurality of radiotelephones over a plurality of frequency
bands and/or a
plurality of air interfaces and an ancillary terrestrial network that is
configured to
communicate terrestrially with the plurality of radiotelephones over
substantially the plurality
of frequency bands and/or substantially the plurality of air interfaces, the
apparatus
comprising: an aggregate radiated power controller that is configured to
control the plurality
of radiotelephones and/or the ancillary terrestrial network so as to limit the
aggregate radiated
power by the plurality of radiotelephones to a maximum aggregate radiated
power; wherein
the aggregate radiated power controller is configured to control the plurality
of
radiotelephones and/or the ancillary terrestrial network, so as to limit the
aggregate radiated
power by a plurality of co-frequency radiotelephones to a maximum aggregate
radiated
power according to the following:
(psd); = MARP ;
where (psd), denotes a measure of radiated power spectral density from an ith
radiotelephone
at a satellite and MARP is a measure of the allowed maximum aggregate radiated
power.
According to another aspect, there is provided a method for controlling a
satellite
radiotelephone system that comprises a space-based component that is
configured to
communicate with a plurality of radiotelephones over a plurality of frequency
bands and/or a
plurality of air interfaces and an ancillary terrestrial network that is
configured to
communicate terrestrially with the plurality of radiotelephones over
substantially the plurality
of frequency bands and/or substantially the plurality of air interfaces, the
method comprising:
controlling the plurality of radiotelephones and/or the ancillary terrestrial
network so as to
limit the aggregate radiated power by the plurality of radiotelephones to a
maximum
aggregate radiated power; wherein the plurality of frequency bands and/or the
plurality of air
interfaces comprise a GSM air interface and a CDMA air interface and wherein
controlling
the plurality of radiotelephones and/or the ancillary terrestrial network, so
as to limit the
aggregate radiated power by the plurality of radiotelephones to a maximum
aggregate
radiated power comprises controlling the plurality of radiotelephones
substantially according
to the following: NGsm+13,800NcDmA/107,894-13,800; where NGSm denotes a number
of co-
frequency time slots that are using the GSM air interface and NCDMA denotes a
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number of co-frequency codes that are using the CDMA air interface.
According to another aspect, there is provided a method for controlling a
satellite
radiotelephone system that comprises a space-based component that is
configured to
communicate with a plurality of radiotelephones over a plurality of frequency
bands and/or a
plurality of air interfaces and an ancillary terrestrial network that is
configured to
communicate terrestrially with the plurality of radiotelephones over
substantially the plurality
of frequency bands and/or substantially the plurality of air interfaces, the
method comprising:
controlling the plurality of radiotelephones and/or the ancillary terrestrial
network so as to
limit the aggregate radiated power by the plurality of radiotelephones to a
maximum
aggregate radiated power; wherein the plurality of frequency bands and/or a
plurality of air
interfaces comprise a GSM air interface, a cdma2000 air interface and/or a W-
CDMA air
interface and wherein controlling the plurality of radiotelephones and/or the
ancillary
terrestrial network, so as to limit the aggregate radiated power by the
plurality of
radiotelephones to a maximum aggregate radiated power comprises controlling
the plurality
of radiotelephones substantially according to the following: N/8+M/50+L/200=R;
where N
denotes a number of co-frequency time slots that are using the GSM air
interface, M denotes
a number of co-frequency codes that are using the cdma2000 air interface, L
denotes a
number of co-frequency codes that are using the W-CDMA air interface, and R
denotes an
authorized GSM-based frequency reuse.
According to another aspect, there is provided a method for controlling a
satellite
radiotelephone system that comprises a space-based component that is
configured to
communicate with a plurality of radiotelephones over a plurality of frequency
bands and/or a
plurality of air interfaces and an ancillary terrestrial network that is
configured to
communicate terrestrially with the plurality of radiotelephones over
substantially the plurality
of frequency bands and/or substantially the plurality of air interfaces, the
method comprising:
controlling the plurality of radiotelephones and/or the ancillary terrestrial
network so as to
limit the aggregate radiated power by the plurality of radiotelephones to a
maximum
aggregate radiated power; wherein controlling the plurality of radiotelephones
and/or the
ancillary terrestrial network, so as to limit the aggregate radiated power by
the plurality of
radiotelephones to a maximum aggregate radiated power is performed according
to the
following:
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x N.
=ARP;
where N, denotes a number of co-frequency channels that are using a given
frequency band
and/or air interface i, F, denotes a corresponding equivalence factor, which
may be less than,
greater than or equal to 1, for the given frequency band/air interface i, and
MARP is a
measure of the maximum aggregate radiated power.
According to another aspect, there is provided a method for controlling a
satellite
radiotelephone system that comprises a space-based component that is
configured to
communicate with a plurality of radiotelephones over a plurality of frequency
bands and/or a
plurality of air interfaces and an ancillary terrestrial network that is
configured to
communicate terrestrially with the plurality of radiotelephones over
substantially the plurality
of frequency bands and/or substantially the plurality of air interfaces, the
method comprising:
controlling the plurality of radiotelephones and/or the ancillary terrestrial
network so as to
limit the aggregate radiated power by the plurality of radiotelephones to a
maximum
aggregate radiated power; wherein controlling the plurality of radiotelephones
and/or the
ancillary terrestrial network, so as to limit the aggregate radiated power by
the plurality of
radiotelephones to a maximum aggregate radiated power is performed according
to the
following:
x N.
=ARP;
where N, denotes a number of co-frequency channels that are using a given
structural
attenuation margin i for a given frequency band and/or air interface, F,
denotes a
corresponding equivalence factor, which may be less than, greater than or
equal to 1, for the
given structural attenuation margin i for the given frequency band/air
interface, and MARP is
a measure of the maximum aggregate radiated power.
According to another aspect, there is provided a method for controlling a
satellite
radiotelephone system that comprises a space-based component that is
configured to
communicate with a plurality of radiotelephones over a plurality of frequency
bands and/or a
plurality of air interfaces and an ancillary terrestrial network that is
configured to
communicate terrestrially with the plurality of radiotelephones over
substantially the plurality
of frequency bands and/or substantially the plurality of air interfaces, the
method comprising:
controlling the plurality of radiotelephones and/or the ancillary terrestrial
network so as to
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limit the aggregate radiated power by the plurality of radiotelephones to a
maximum
aggregate radiated power; wherein controlling the plurality of radiotelephones
and/or the
ancillary terrestrial network, so as to limit the aggregate radiated power by
a plurality of co-
frequency radiotelephones to a maximum aggregate radiated power is performed
according to
the following:
E(psd); MARP ;
where (psd), denotes a measure of radiated power spectral density from an ith
radiotelephone
at a satellite and MARP is a measure of the allowed maximum aggregate radiated
power.
According to another aspect, there is provided an ancillary terrestrial
network for a
satellite radiotelephone system that includes a space-based component that is
configured to
communicate with a plurality of radiotelephones over a satellite frequency
band, the ancillary
terrestrial network comprising: a plurality of ancillary terrestrial
components that are
configured to communicate terrestrially with the plurality of radiotelephones
over
substantially the satellite frequency band; and a diversity receiver that is
configured to
diversity combine at least two satellite frequency band signals from a
radiotelephone that are
received by a first ancillary terrestrial component, that are received by a
second ancillary
terrestrial component and/or that are received by an auxiliary antenna system.
According to another aspect, there is provided a first ancillary terrestrial
component
for a satellite radiotelephone system that includes a space-based component
that is configured
to communicate with a plurality of radiotelephones over a satellite frequency
band, the first
ancillary terrestrial component comprising: a subsystem that is configured to
communicate
terrestrially with the plurality of radiotelephones over substantially the
satellite frequency
band; and a diversity receiver that is configured to diversity combine at
least two satellite
frequency band signals from a radiotelephone that are received by the first
ancillary terrestrial
component, by a second ancillary terrestrial component and/or by an auxiliary
antenna
system.
According to another aspect, there is provided a method for increasing link
margin in
a satellite radiotelephone system that includes a space-based component that
is configured to
communicate with a plurality of radiotelephones over a satellite frequency
band and a
plurality of ancillary terrestrial components that are configured to
communicate terrestrially
with the plurality of radiotelephones over substantially the satellite
frequency band, the
method comprising: diversity combining at least two satellite frequency band
signals from a
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radiotelephone that are received by a first ancillary terrestrial component,
that are received by
a second ancillary terrestrial component and/or that are received by an
auxiliary antenna
system.
According to another aspect, there is provided an ancillary terrestrial
network for a
satellite radiotelephone system that includes a space-based component that is
configured to
communicate with a plurality of radiotelephones, the ancillary terrestrial
network comprising:
a plurality of ancillary terrestrial components that are configured to
communicate terrestrially
with the plurality of radiotelephones using satellite frequency band signals;
and a diversity
receiver that is configured to diversity combine at least two satellite
frequency band signals
from a radiotelephone that are received by a first ancillary terrestrial
component, that are
received by a second ancillary terrestrial component and/or that are received
by an auxiliary
antenna system.
According to another aspect, there is provided a first ancillary terrestrial
component
for a satellite radiotelephone system that includes a space-based component
that is configured
to communicate with a plurality of radiotelephones, the first ancillary
terrestrial component
comprising: a subsystem that is configured to communicate terrestrially with
the plurality of
radiotelephones using satellite frequency band signals; and
a diversity receiver that is configured to diversity combine at least two
satellite frequency
band signals from a radiotelephone that are received by the first ancillary
terrestrial
component, by a second ancillary terrestrial component and/or by an auxiliary
antenna
system.
According to another aspect, there is provided a method for increasing link
margin in
a satellite radiotelephone system that includes a space-based component that
is configured to
communicate with a plurality of radiotelephones and a plurality of ancillary
terrestrial
components that are configured to communicate terrestrially with the plurality
of
radiotelephones using satellite frequency band signals, the method comprising:
diversity
combining at least two satellite frequency band signals from a radiotelephone
that are
received by a first ancillary terrestrial component, that are received by a
second ancillary
terrestrial component and/or that are received by an auxiliary antenna system.
According to another aspect, there is provided a method of controlling a level
of
interference to a wireless receiver, the method comprising: determining a set
of frequencies
to be assigned to a wireless transmitter responsive to a power level
associated with the
wireless transmitter; and assigning
the set of frequencies to the wireless transmitter;
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wherein determining comprises increasing a frequency distance between the set
of
frequencies and a band of frequencies used for reception by the wireless
receiver as the
power level increases; and wherein determining further comprises decreasing a
frequency
distance between the set of frequencies and a band of frequencies used for
reception by the
wireless receiver as the power level decreases.
According to another aspect, there is provided a system for controlling a
level of
interference to a wireless receiver, the system comprising: a wireless
transmitter; and a
controller that is configured to determine a set of frequencies to be assigned
to a wireless
transmitter responsive to a power level associated with the wireless
transmitter;
wherein the controller is further configured to increase a frequency distance
between the set
of frequencies and a band of frequencies used for reception by the wireless
receiver as the
power level increases; and wherein the controller is still further configured
to decrease a
frequency distance between the set of frequencies and a band of frequencies
used for
reception by the wireless receiver as the power level decreases.
According to another aspect, there is provided a radiotelephone system
comprising: a
wireless network that is configured to communicate bidirectionally with a
plurality of
radiotelephones using at least one air interface protocol and a frequency; and
an aggregate
radiated power controller that is configured to limit an aggregate radiated
power by the
plurality of radiotelephones that use the at least one air interface protocol
and the frequency
by controlling at least one of the radiotelephones to use another frequency
that has not
exceeded its maximum aggregate radiated power; wherein controlling at least
one of the
radiotelephones to use another frequency that has not exceeded its maximum
aggregate
radiated power comprises: the aggregate radiated power controller evaluating
an expression
that depends upon a structural attenuation margin that is provided to the at
least one of the
radiotelephones by the wireless network; and the aggregate radiated power
controller
controlling at least one of the radiotelephones to use another frequency that
has not exceeded
its maximum aggregate radiated power, responsive to the evaluating an
expression that
depends upon a structural attenuation margin that is provided to the at least
one of the
radiotelephones by the wireless network.
According to another aspect, there is provided a radiotelephone communications
method comprising: bidirectionally communicating with a plurality of
radiotelephones using
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at least one air interface protocol and a frequency; and limiting an aggregate
radiated power
by the plurality of radiotelephones that use the at least one air interface
protocol and the
frequency by controlling at least one of the radiotelephones to use another
frequency that has
not exceeded its maximum aggregate radiated power; wherein controlling at
least one of the
radiotelephones to use another frequency that has not exceeded its maximum
aggregate
radiated power comprises: evaluating an expression that depends upon a
structural
attenuation margin that is provided to the at least one of the radiotelephones
by a wireless
network that communicates therewith; and controlling at least one of the
radiotelephones to
use another frequency that has not exceeded its maximum aggregate radiated
power,
responsive to the evaluating an expression that depends upon a structural
attenuation margin
that is provided to the at least one of the radiotelephones by a wireless
network that
communicates therewith.
According to another aspect, there is provided an apparatus for controlling a
radiotelephone system that comprises a wireless network that is configured to
communicate
bidirectionally with a plurality of radiotelephones using at least one air
interface protocol and
a frequency, the apparatus comprising: an aggregate radiated power controller
that is
configured to limit an aggregate radiated power by the plurality of
radiotelephones that use
the at least one air interface protocol and the frequency by controlling at
least one of the
radiotelephones to use another frequency that has not exceeded its maximum
aggregate
radiated power; wherein controlling at least one of the radiotelephones to use
another
frequency that has not exceeded its maximum aggregate radiated power
comprises: the
aggregate radiated power controller evaluating an expression that depends upon
a structural
attenuation margin that is provided to the at least one of the radiotelephones
by the wireless
network; and the aggregate radiated power controller controlling at least one
of the
radiotelephones to use another frequency that has not exceeded its maximum
aggregate
radiated power, responsive to the evaluating an expression that depends upon a
structural
attenuation margin that is provided to the at least one of the radiotelephones
by the wireless
network.
According to another aspect, there is provided a method for controlling a
radiotelephone system that comprises a wireless network that is configured to
communicate
bidirectionally with a plurality of radiotelephones using at least one air
interface protocol and
a frequency, the method comprising: limiting an aggregate radiated power by
the plurality of
radiotelephones that use the at least one air interface protocol and the
frequency by
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controlling at least one of the radiotelephones to use another frequency that
has not exceeded
its maximum aggregate radiated power; wherein controlling at least one of the
radiotelephones to use another frequency that has not exceeded its maximum
aggregate
radiated power comprises: evaluating an expression that depends upon a
structural
attenuation margin that is provided to the at least one of the radiotelephones
by the wireless
network; and controlling at least one of the radiotelephones to use another
frequency that has
not exceeded its maximum aggregate radiated power, responsive to the
evaluating an
expression that depends upon a structural attenuation margin that is provided
to the at least
one of the radiotelephones by the wireless network.
According to another aspect, there is provided a method of controlling a
cellular
communications system, the method comprising: identifying a power level to be
used by a
wireless transmitter of the cellular communications system, the wireless
transmitter
configured to transmit over a set of frequencies that is assigned to a given
cell of the cellular
communications system in a band of frequencies that is assigned to the
cellular
communications system; determining a subset of frequencies in the set of
frequencies that is
assigned to the given cell, the subset of frequencies to be assigned to the
wireless transmitter
responsive to the identified power level to be used by the wireless
transmitter; assigning the
subset of frequencies in the set of frequencies that is assigned to the given
cell to the wireless
transmitter for transmission at the identified power level; and wherein the
set of frequencies
that is assigned to the given cell of the cellular communications system is in
a satellite band
of frequencies.
According to another aspect, there is provided a cellular communications
system
comprising: a wireless transmitter that is configured to transmit over a set
of frequencies that
is assigned to a given cell of the cellular communications system in a band of
frequencies that
is assigned to the cellular communications system; a controller that is
configured to identify a
power level to be used by the wireless transmitter and to determine a subset
of frequencies in
the set of frequencies that is assigned to the given cell of the cellular
communications system,
the subset of frequencies to be assigned to the wireless transmitter
responsive to the power
level that was identified; and wherein the set of frequencies that is assigned
to the given cell
of the cellular communications system is in a satellite band of frequencies.
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Brief Description of the Drawings
Figure 1 is a schematic diagram of cellular radiotelephone systems and methods
according to embodiments of the invention.
Figure 2 is a block diagram of adaptive interference reducers according to
embodiments of the present invention.
Figure 3 is a spectrum diagram that illustrates satellite L-band frequency
allocations.
Figure 4 is a schematic diagram of cellular satellite systems and methods
according
to other embodiments of the present invention.
Figure 5 illustrates time division duplex frame structures according to
embodiments
of the present invention.
Figure 6 is a block diagram of architectures of ancillary terrestrial
components according
to embodiments of the invention.
Figure 7 is a block diagram of architectures of reconfigurable radiotelephones
according
to embodiments of the invention.
Figure 8 graphically illustrates mapping of monotonically decreasing power
levels to
frequencies according to embodiments of the present invention.
Figure 9 illustrates an ideal cell that is mapped to three power regions and
three
associated carrier frequencies according to embodiments of the invention.
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6
Figure 10 depicts a realistic cell that is mapped to three power regions and
three
associated carrier frequencies according to embodiments of the invention.
Figure 11 illustrates two or more contiguous slots in a frame that are
unoccupied
according to embodiments of the present invention.
Figure 12 illustrates loading of two or more contiguous slots with lower power
transmissions according to embodiments of the present invention.
Figure 13 is a block diagram of satellite radiotelephone systems and methods
according to some embodiments of the invention.
Figure 14 is a schematic diagram of terrestrial frequency reuse of satellite
frequencies
according to some embodiments of the invention.
Figure 15 is a block diagram of radiotelephones according to some embodiments
of
the invention.
Figure 16 is a schematic diagram of satellite radiotelephone systems and
methods
according to some embodiments of the invention.
Figure 17 is a schematic diagram of satellite radiotelephone systems and
methods
according to some embodiments of the invention.
Figure 18 is a schematic diagram of satellite radiotelephone systems and
methods
including aggregate radiated power control according to some embodiments of
the present
invention.
Figure 19 is a schematic diagram of an ancillary terrestrial network including
systems
and methods that can increase link margins according to some embodiments of
the present
invention.
Detailed Description of Preferred Embodiments
The present invention now will be described more fully hereinafter with
reference to
the accompanying drawings, in which embodiments of the invention are shown.
However,
this invention should not be construed as limited to the embodiments set forth
herein. Rather,
these embodiments are provided so that this disclosure will be thorough and
complete, and
will fully convey the scope of the invention to those skilled in the art. Like
numbers refer to
like elements throughout.
Figure 1 is a schematic diagram of cellular satellite radiotelephone systems
and
methods according to embodiments of the invention. As shown in Figure 1, these
cellular
satellite radiotelephone systems and methods 100 include at least one Space-
Based
Component (SBC) 110, such as a satellite. The space-based component 110 is
configured to
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7
transmit wireless communications to a plurality of radiotelephones 120a, 120b
in a satellite
footprint comprising one or more satellite radiotelephone cells 130-130" over
one or more
satellite radiotelephone forward link (downlink) frequencies fp. The space-
based component
110 is configured to receive wireless communications from, for example, a
first
radiotelephone 120a in the satellite radiotelephone cell 130 over a satellite
radiotelephone
return link (uplink) frequency fu. An ancillary terrestrial network,
comprising at least one
ancillary terrestrial component 140, which may include an antenna 140a and an
electronics
system 140b (for example, at least one antenna 140a and at least one
electronics system
140b), is configured to receive wireless communications from, for example, a
second
radiotelephone 120b in the radiotelephone cell 130 over the satellite
radiotelephone uplink
frequency, denoted fu, which may be the same as fu. Thus, as illustrated in
Figure 1,
radiotelephone 120a may be communicating with the space-based component 110
while
radiotelephone 120b may be communicating with the ancillary terrestrial
component 140. As
shown in Figure 1, the space-based component 110 also undesirably receives the
wireless
communications from the second radiotelephone 120b in the satellite
radiotelephone cell 130
over the satellite radiotelephone frequency fu as interference. More
specifically, a potential
interference path is shown at 150. In this potential interference path 150,
the return link
signal of the second radiotelephone 120b at carrier frequency fu interferes
with satellite
communications. This interference would generally be strongest when fu = fu,
because, in
that case, the same return link frequency would be used for space-based
component and
ancillary terrestrial component communications over the same satellite
radiotelephone cell,
and no spatial discrimination between satellite radiotelephone cells would
appear to exist.
Still referring to Figure 1, embodiments of satellite radiotelephone
systems/methods
100 can include at least one gateway 160 that can include an antenna 160a and
an electronics
system 160b that can be connected to other networks 162 including terrestrial
and/or other
radiotelephone networks. The gateway 160 also communicates with the space-
based
component 110 over a satellite feeder link 112. The gateway 160 also
communicates with the
ancillary terrestrial component 140, generally over a terrestrial link 142.
Still referring to Figure 1, an Interference Reducer (IR) 170a also may be
provided at
least partially in the ancillary terrestrial component electronics system
140b. Alternatively or
additionally, an interference reducer 170b may be provided at least partially
in the gateway
electronics system 160b. In yet other alternatives, the interference reducer
may be provided
at least partially in other components of the cellular satellite system/method
100 instead of or
in addition to the interference reducer 170a and/or 170b. The interference
reducer is
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8
responsive to the space-based component 110 and to the ancillary terrestrial
component 140,
and is configured to reduce the interference from the wireless communications
that are
received by the space-based component 110 and is at least partially generated
by the second
radiotelephone 120b in the satellite radiotelephone cell 130 over the
satellite radiotelephone
frequency fu. The interference reducer 170a and/or 170b uses the wireless
communications
fu that are intended for the ancillary terrestrial component 140 from the
second
radiotelephone 120b in the satellite radiotelephone cell 130 using the
satellite radiotelephone
frequency fu to communicate with the ancillary terrestrial component 140.
In embodiments of the invention, as shown in Figure 1, the ancillary
terrestrial
component 140 generally is closer to the first and second radiotelephones 120a
and 120b,
respectively, than is the space-based component 110, such that the wireless
communications
from the second radiotelephone 120b are received by the ancillary terrestrial
component 140
prior to being received by the space-based component 110. The interference
reducer 170a
and/or 170b is configured to generate an interference cancellation signal
comprising, for
example, at least one delayed replica of the wireless communications from the
second
radiotelephone 120b that are received by the ancillary terrestrial component
140, and to
subtract the delayed replica of the wireless communications from the second
radiotelephone
120b that are received by the ancillary terrestrial component 140 from the
wireless
communications that are received from the space-based component 110. The
interference
reduction signal may be transmitted from the ancillary terrestrial component
140 to the
gateway 160 over link 142 and/or using other conventional techniques.
Thus, adaptive interference reduction techniques may be used to at least
partially
cancel the interfering signal, so that the same, or other nearby, satellite
radiotelephone uplink
frequency can be used in a given cell for communications by radiotelephones
120 with the
satellite 110 and with the ancillary terrestrial component 140. Accordingly,
all frequencies
that are assigned to a given cell 130 may be used for both radiotelephone 120
communications with the space-based component 110 and with the ancillary
terrestrial
component 140. Conventional systems may avoid terrestrial reuse of frequencies
within a
given satellite cell that are being used within the satellite cell for
satellite communications.
Stated differently, conventionally, only frequencies used by other satellite
cells may be
candidates for terrestrial reuse within a given satellite cell. Beam-to-beam
spatial isolation
that is provided by the satellite system was relied upon to reduce or minimize
the level of
interference from the terrestrial operations into the satellite operations. In
sharp contrast,
embodiments of the invention can use an interference reducer to allow all
frequencies
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assigned to a satellite cell to be used terrestrially and for satellite
radiotelephone
communications.
Embodiments of the invention according to Figure 1 may arise from a
realization that
the return link signal from the second radiotelephone 120b at fu generally
will be received
and processed by the ancillary terrestrial component 140 much earlier relative
to the time
when it will arrive at the satellite gateway 160 from the space-based
component 110 via the
interference path 150. Accordingly, the interference signal at the satellite
gateway 160b can
be at least partially canceled. Thus, as shown in Figure 1, an interference
cancellation signal,
such as the demodulated ancillary terrestrial component signal, can be sent to
the satellite
gateway 160b by the interference reducer 170a in the ancillary terrestrial
component 140, for
example using link 142. In the interference reducer 170b at the gateway 160b,
a weighted (in
amplitude and/or phase) replica of the signal may be formed using, for
example, adaptive
transversal filter techniques that are well known to those having skill in the
art. Then, a
transversal filter output signal is subtracted from the aggregate received
satellite signal at
frequency fu that contains desired as well as interference signals. Thus, the
interference
cancellation need not degrade the signal-to-noise ratio of the desired signal
at the gateway
160, because a regenerated (noise-free) terrestrial signal, for example as
regenerated by the
ancillary terrestrial component 140, can be used to perform interference
suppression.
Figure 2 is a block diagram of embodiments of adaptive interference cancellers
that
may be located in the ancillary terrestrial component 140, in the gateway 160,
and/or in
another component of the cellular radiotelephone system 100. As shown in
Figure 2, one or
more control algorithms 204, known to those having skill in the art, may be
used to
adaptively adjust the coefficients of a plurality of transversal filters 202a-
202n. Adaptive
algorithms, such as Least Mean Square Error (LMSE), Kalman, Fast Kalman, Zero
Forcing
and/or various combinations thereof or other techniques may be used. It will
be understood
by those having skill in the art that the architecture of Figure 2 may be used
with an LMSE
algorithm. However, it also will be understood by those having skill in the
art that
conventional architectural modifications may be made to facilitate other
control algorithms.
Additional embodiments of the invention now will be described with reference
to
Figure 3, which illustrates L-band frequency allocations including cellular
radiotelephone
system forward links and return links. As shown in Figure 3, the space-to-
ground L-band
forward link (downlink) frequencies are assigned from 1525 MHz to 1559 MHz.
The
ground-to-space L-band return link (uplink) frequencies occupy the band from
1626.5 MHz
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WO 2004/100501 PCT/US2004/012541
to 1660.5 MHz. Between the forward and return L-band links lie the GPS/GLONASS
radionavigation band (from 1559 MHz to 1605 MHz).
In the detailed description to follow, GPS/GLONASS will be referred to simply
as
GPS for the sake of brevity. Moreover, the acronyms ATC and SBC will be used
for the
5 ancillary terrestrial component and the space-based component,
respectively, for the sake of
brevity.
As is known to those skilled in the art, GPS receivers may be extremely
sensitive
since they are designed to operate on very weak spread-spectrum
radionavigation signals that
arrive on the earth from a GPS satellite constellation. As a result, GPS
receivers may to be
10 highly susceptible to in-band interference. ATCs that are configured to
radiate L-band
frequencies in the forward satellite band (1525 to 1559 MHz) can be designed
with very
sharp out-of-band emissions filters to satisfy the stringent out-of-band
spurious emissions
desires of GPS.
Referring again to Figure 1, some embodiments of the invention can provide
systems
and methods that can allow an ATC 140 to configure itself in one of at least
two modes. In
accordance with a first mode, which may be a standard mode and may provide
highest
capacity, the ATC 140 transmits to the radiotelephones 120 over the frequency
range from
1525 MHz to 1559 MHz, and receives transmissions from the radiotelephones 120
in the
frequency range from 1626.5 MHz to 1660.5 MHz, as illustrated in Figure 3. In
contrast, in a
second mode of operation, the ATC 140 transmits wireless communications to the
radiotelephones 120 over a modified range of satellite band forward link
(downlink)
frequencies. The modified range of satellite band forward link frequencies may
be selected
to reduce, compared to the unmodified range of satellite band forward link
frequencies,
interference with wireless receivers such as GPS receivers that operate
outside the range of
satellite band forward link frequencies.
Many modified ranges of satellite band forward link frequencies may be
provided
according to embodiments of the present invention. In some embodiments, the
modified
range of satellite band forward link frequencies can be limited to a subset of
the original
range of satellite band forward link frequencies, so as to provide a guard
band of unused
satellite band forward link frequencies. In other embodiments, all of the
satellite band
forward link frequencies are used, but the wireless communications to the
radiotelephones are
modified in a manner to reduce interference with wireless receivers that
operate outside the
range of satellite band forward link frequencies. Combinations and
subcombinations of these
and/or other techniques also may be used, as will be described below.
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It also will be understood that embodiments of the invention that will now be
described in connection with Figures 4-12 will be described in terms of
multiple mode ATCs
140 that can operate in a first standard mode using the standard forward and
return links of
Figure 3, and in a second or alternate mode that uses a modified range of
satellite band
forward link frequencies and/or a modified range of satellite band return link
frequencies.
These multiple mode ATCs can operate in the second, non-standard mode, as long
as
desirable, and can be switched to standard mode otherwise. However, other
embodiments of
the present invention need not provide multiple mode ATCs but, rather, can
provide ATCs
that operate using the modified range of satellite band forward link and/or
return link
frequencies.
Embodiments of the invention now will be described, wherein an ATC operates
with
an SBC that is configured to receive wireless communications from
radiotelephones over a
first range of satellite band return link frequencies and to transmit wireless
communications
to the radiotelephones over a second range of satellite band forward link
frequencies that is
spaced apart from the first range. According to these embodiments, the ATC is
configured to
use at least one time division duplex frequency to transmit wireless
communications to the
radiotelephones and to receive wireless communications from the
radiotelephones at different
times. In particular, in some embodiments, the at least one time division
duplex frequency
that is used to transmit wireless communications to the radiotelephones and to
receive
wireless communications from the radiotelephones at different times, comprises
a frame
including a plurality of slots. At least a first one of the slots is used to
transmit wireless
communications to the radiotelephones and at least a second one of the slots
is used to
receive wireless communications from the radiotelephones. Thus, in some
embodiments, the
ATC transmits and receives, in Time Division Duplex (TDD) mode, using
frequencies from
1626.5 MHz to 1660.5 MHz. In some embodiments, all ATCs across the entire
network may
have the stated configuration/reconfiguration flexibility. In other
embodiments, only some
ATCs may be reconfigurable.
Figure 4 illustrates satellite systems and methods 400 according to some
embodiments
of the invention, including an ATC 140 communicating with a radiotelephone
120b using a
carrier frequency f'u in TDD mode. Figure 5 illustrates an embodiment of a TDD
frame
structure. Assuming full-rate GSM (eight time slots per frame), up to four
full-duplex voice
circuits can be supported by one TDD carrier. As shown in Figure 5, the ATC
140 transmits
to the radiotelephone 120b over, for example, time slot number 0. The
radiotelephone 120b
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receives and replies back to the ATC 140 over, for example, time slot number
4. Time slots
number 1 and 5 may be used to establish communications with another
radiotelephone, and
so on.
A Broadcast Control CHannel (BCCH) is preferably transmitted from the ATC 140
in
standard mode, using a carrier frequency from below any guard band exclusion
region. In
other embodiments, a BCCH also can be defined using a TDD carrier. In any of
these
embodiments, radiotelephones in idle mode can, per established GSM
methodology, monitor
the BCCH and receive system-level and paging information. When a
radiotelephone is
paged, the system decides what type of resource to allocate to the
radiotelephone in order to
establish the communications link. Whatever type of resource is allocated for
the
radiotelephone communications channel (TDD mode or standard mode), the
information is
communicated to the radiotelephone, for example as part of the call
initialization routine, and
the radiotelephone configures itself appropriately.
It may be difficult for the TDD mode to co-exist with the standard mode over
the
same ATC, due, for example, to the ATC receiver LNA stage. In particular,
assuming a
mixture of standard and TDD mode GSM carriers over the same ATC, during the
part of the
frame when the TDD carriers are used to serve the forward link (when the ATC
is
transmitting TDD) enough energy may leak into the receiver front end of the
same ATC to
desensitize its LNA stage.
Techniques can be used to suppress the transmitted ATC energy over the 1600
MHz
portion of the band from desensitizing the ATC's receiver LNA, and thereby
allow mixed
standard mode and TDD frames. For example, isolation between outbound and
inbound
ATC front ends and/or antenna system return loss may be increased or
maximized. A
switchable band-reject filter may be placed in front of the LNA stage. This
filter would be
switched in the receiver chain (prior to the LNA) during the part of the frame
when the ATC
is transmitting TDD, and switched out during the rest of the time. An adaptive
interference
canceller can be configured at RF (prior to the LNA stage). If such techniques
are used,
suppression of the order of 70 dB can be attained, which may allow mixed
standard mode and
TDD frames. However, the ATC complexity and/or cost may increase.
Thus, even though ATC LNA desensitization may be reduced or eliminated, it may
use significant special engineering and attention and may not be economically
worth the
effort. Other embodiments, therefore, may keep TDD ATCs pure TDD, with the
exception,
perhaps, of the BCCH carrier which may not be used for traffic but only for
broadcasting
over the first part of the frame, consistent with TDD protocol. Moreover,
Random Access
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CHannel (RACH) bursts may be timed so that they arrive at the ATC during the
second half
of the TDD frame. In some embodiments, all TDD ATCs may be equipped to enable
reconfiguration in response to a command.
It is well recognized that during data communications or other applications,
the
forward link may use transmissions at higher rates than the return link. For
example, in web
browsing with a radiotelephone, mouse clicks and/or other user selections
typically are
transmitted from the radiotelephone to the system. The system, however, in
response to a
user selection, may have to send large data files to the radiotelephone.
Hence, other
embodiments of the invention may be configured to enable use of an increased
or maximum
number of time slots per forward GSM carrier frame, to provide a higher
downlink data rate
to the radiotelephones.
Thus, when a carrier frequency is configured to provide service in TDD mode, a
decision may be made as to how many slots will be allocated to serving the
forward link, and
how many will be dedicated to the return link. Whatever the decision is, it
may be desirable
that it be adhered to by all TDD carriers used by the ATC, in order to reduce
or avoid the
LNA desensitization problem described earlier. In voice communications, the
partition
between forward and return link slots may be made in the middle of the frame
as voice
activity typically is statistically bidirectionally symmetrical. Hence, driven
by voice, the
center of the frame may be where the TDD partition is drawn.
To increase or maximize forward link throughput in data mode, data mode TDD
carriers according to embodiments of the invention may use a more spectrally
efficient
modulation and/or protocol, such as the EDGE modulation and/or protocol, on
the forward
link slots. The return link slots may be based on a less spectrally efficient
modulation and/or
protocol such as the GPRS (GMSK) modulation and/or protocol. The EDGE
modulation/protocol and the GPRS modulation/protocol are well known to those
having skill
in the art, and need not be described further herein. Given an EDGE
forward/GPRS return
TDD carrier strategy, up to (384/2) = 192 kbps may be supported on the forward
link while
on the return link the radiotelephone may transmit at up to (115/2) 64 kbps.
In other embodiments, it also is possible to allocate six time slots of an
eight-slot
frame for the forward link and only two for the return link. In these
embodiments, for voice
services, given the statistically symmetric nature of voice, the return link
vocoder may need
to be comparable with quarter-rate GSM, while the forward link vocoder can
operate at full-
rate GSM, to yield six full-duplex voice circuits per GSM TDD-mode carrier (a
voice
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capacity penalty of 25%). Subject to this non-symmetrical partitioning
strategy, data rates of
up to (384)(6/8) = 288 kbps may be achieved on the forward link, with up to
(115)(2/8) 32
kbps on the return link.
Figure 6 depicts an ATC architecture according to embodiments of the
invention,
which can lend itself to automatic configuration between the two modes of
standard GSM
and TDD GSM on command, for example, from a Network Operations Center (NOC)
via a
Base Station Controller (BSC). It will be understood that in these
embodiments, an antenna
620 can correspond to the antenna 140a of Figures 1 and 4, and the remainder
of Figure 6 can
correspond to the electronics system 140b of Figures 1 and 4. If a
reconfiguration command
for a particular carrier, or set of carriers, occurs while the carrier(s) are
active and are
supporting traffic, then, via the in-band signaling Fast Associated Control
CHannel
(FACCH), all affected radiotelephones may be notified to also reconfigure
themselves and/or
switch over to new resources. If carrier(s) are reconfigured from TDD mode to
standard
mode, automatic reassignment of the carrier(s) to the appropriate standard-
mode ATCs,
based, for example, on capacity demand and/or reuse pattern can be initiated
by the NOC. If,
on the other hand, carrier(s) are reconfigured from standard mode to TDD mode,
automatic
reassignment to the appropriate TDD-mode ATCs can take place on command from
the
NOC.
Still referring to Figure 6, a switch 610 may remain closed when carriers are
to be
demodulated in the standard mode. In TDD mode, this switch 610 may be open
during the
first half of the frame, when the ATC is transmitting, and closed during the
second half of the
frame, when the ATC is receiving. Other embodiments also may be provided.
Figure 6 assumes N transceivers per ATC sector, where N can be as small as
one,
since a minimum of one carrier per sector generally is desired. Each
transceiver is assumed
to operate over one GSM carrier pair (when in standard mode) and can thus
support up to
eight full-duplex voice circuits, neglecting BCCH channel overhead. Moreover,
a standard
GSM carrier pair can support sixteen full-duplex voice circuits when in half-
rate GSM mode,
and up to thirty two full-duplex voice circuits when in quarter-rate GSM mode.
When in TDD mode, the number of full duplex voice circuits may be reduced by a
factor of two, assuming the same vocoder. However, in TDD mode, voice service
can be
offered via the half-rate GSM vocoder with almost imperceptible quality
degradation, in
order to maintain invariant voice capacity. Figure 7 is a block diagram of a
reconfigurable
radiotelephone architecture that can communicate with a reconfigurable ATC
architecture of
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Figure 6. In Figure 7, an antenna 720 is provided, and the remainder of Figure
7 can provide
embodiments of an electronics system for the radiotelephone.
It will be understood that the ability to reconfigure ATCs and radiotelephones
according to embodiments of the invention may be obtained at a relatively
small increase in
5 cost. The cost may be mostly in Non-Recurring Engineering (NRE) cost to
develop software.
Some recurring cost may also be incurred, however, in that at least an
additional RF filter and
a few electronically controlled switches may be used per ATC and
radiotelephone. All other
hardware/software can be common to standard-mode and TDD-mode GSM.
Referring now to Figure 8, other radiotelephone systems and methods according
to
10 embodiments of the invention now will be described. In these
embodiments, the modified
second range of satellite band forward link frequencies includes a plurality
of frequencies in
the second range of satellite band forward link frequencies that are
transmitted by the ATCs
to the radiotelephones at a power level, such as maximum power level, that
monotonically
decreases as a function of (increasing) frequency. More specifically, as will
be described
15 below, in some embodiments, the modified second range of satellite band
forward link
frequencies includes a subset of frequencies proximate to a first or second
end of the range of
satellite band forward link frequencies that are transmitted by the ATC to the
radiotelephones
at a power level, such as a maximum power level, that monotonically decreases
toward the
first or second end of the second range of satellite band forward link
frequencies. In still
other embodiments, the first range of satellite band return link frequencies
is contained in an
L-band of satellite frequencies above GPS frequencies and the second range of
satellite band
forward link frequencies is contained in the L-band of satellite frequencies
below the GPS
frequencies. The modified second range of satellite band forward link
frequencies includes a
subset of frequencies proximate to an end of the second range of satellite
band forward link
frequencies adjacent the GPS frequencies that are transmitted by the ATC to
the
radiotelephones at a power level, such as a maximum power level, that
monotonically
decreases toward the end of the second range of satellite band forward link
frequencies
adjacent the GPS frequencies.
Without being bound by any theory of operation, a theoretical discussion of
the
mapping of ATC maximum power levels to carrier frequencies according to
embodiments of
the present invention now will be described. Referring to Figure 8, let v =
,T(p) represent a
mapping from the power (p) domain to the frequency (v) range. The power (p) is
the power
that an ATC uses or should transmit in order to reliably communicate with a
given
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radiotelephone. This power may depend on many factors such as the
radiotelephone's
distance from the ATC, the blockage between the radiotelephone and the ATC,
the level of
multipath fading in the channel, etc., and as a result, will, in general,
change as a function of
time. Hence, the power used generally is determined adaptively (iteratively)
via closed-loop
power control, between the radiotelephone and ATC.
The frequency (V) is the satellite carrier frequency that the ATC uses to
communicate
with the radiotelephone. According to embodiments of the invention, the
mapping (T'is a
monotonically decreasing function of the independent variable p. Consequently,
in some
embodiments, as the maximum ATC power increases, the carrier frequency that
the ATC
uses to establish and/or maintain the communications link decreases. Figure 8
illustrates an
embodiment of a piece-wise continuous monotonically decreasing (stair-case)
function.
Other monotonic functions may be used, including linear and/or nonlinear,
constant and/or
variable decreases. FACCH or Slow Associated Control CHannel (SACCH) messaging
may
be used in embodiments of the invention to facilitate the mapping adaptively
and in
substantially real time.
Figure 9 depicts an ideal cell according to embodiments of the invention,
where, for
illustration purposes, three power regions and three associated carrier
frequencies (or carrier
frequency sets) are being used to partition a cell. For simplicity, one ATC
transmitter at the
center of the idealized cell is assumed with no sectorization. In embodiments
of Figure 9, the
frequency (or frequency set) f1 is taken from substantially the upper-most
portion of the L-
band forward link frequency set, for example from substantially close to 1559
MHz (see
Figure 3). Correspondingly, the frequency (or frequency set) fm is taken from
substantially
the central portion of the L-band forward link frequency set (see Figure 3).
In concert with
the above, the frequency (or frequency set) fo is taken from substantially the
lowest portion
of the L-band forward link frequencies, for example close to 1525 MHz (see
Figure 3).
Thus, according to embodiments of Figure 9, if a radiotelephone is being
served
within the outer-most ring of the cell, that radiotelephone is being served
via frequency fo.
This radiotelephone, being within the furthest area from the ATC, has
(presumably) requested
maximum (or near maximum) power output from the ATC. In response to the
maximum (or
near maximum) output power request, the ATC uses its a priori knowledge of
power-to-
frequency mapping, such as a three-step staircase function of Figure 9. Thus,
the ATC serves
the radiotelephone with a low-value frequency taken from the lowest portion of
the mobile L-
band forward link frequency set, for example, from as close to 1525 MHz as
possible. This,
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then, can provide additional safeguard to any GPS receiver unit that may be in
the vicinity of
the ATC.
Embodiments of Figure 9 may be regarded as idealized because they associate
concentric ring areas with carrier frequencies (or carrier frequency sets)
used by an ATC to
serve its area. In reality, concentric ring areas generally will not be the
case. For example, a
radiotelephone can be close to the ATC that is serving it, but with
significant blockage
between the radiotelephone and the ATC due to a building. This radiotelephone,
even though
relatively close to the ATC, may also request maximum (or near maximum) output
power
from the ATC. With this in mind, Figure 10 may depict a more realistic set of
area contours
that may be associated with the frequencies being used by the ATC to serve its
territory,
according to embodiments of the invention. The frequency (or frequency set) fI
may be
reused in the immediately adjacent ATC cells owing to the limited geographical
span
associated with fi relative to the distance between cell centers. This may
also hold for fm.
Referring now to Figure 11, other modified second ranges of satellite band
forward
link frequencies that can be used by ATCs according to embodiments of the
present invention
now will be described. In these embodiments, at least one frequency in the
modified second
range of satellite band forward link frequencies that is transmitted by the
ATC to the
radiotelephones comprises a frame including a plurality of slots. In these
embodiments, at
least two contiguous slots in the frame that is transmitted by the ATC to the
radiotelephones
are left unoccupied. In other embodiments, three contiguous slots in the frame
that is
transmitted by the ATC to the radiotelephones are left unoccupied. In yet
other
embodiments, at least two contiguous slots in the frame that is transmitted by
the ATC to the
radiotelephones are transmitted at lower power than remaining slots in the
frame. In still
other embodiments, three contiguous slots in the frame that is transmitted by
the ATC to the
radiotelephones are transmitted at lower power than remaining slots in the
frame. In yet other
embodiments, the lower power slots may be used with first selected ones of the
radiotelephones that are relatively close to the ATC and/or are experiencing
relatively small
signal blockage, and the remaining slots are transmitted at higher power to
second selected
ones of the radiotelephones that are relatively far from the ATC and/or are
experiencing
relatively high signal blockage.
Stated differently, in accordance with some embodiments of the invention, only
a
portion of the TDMA frame is utilized. For example, only the first four (or
last four, or any
contiguous four) time slots of a full-rate GSM frame are used to support
traffic. The
remaining slots are left unoccupied (empty). In these embodiments, capacity
may be lost.
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However, as has been described previously, for voice services, half-rate and
even quarter-rate
GSM may be invoked to gain capacity back, with some potential degradation in
voice quality.
The slots that are not utilized preferably are contiguous, such as slots 0
through 3 or 4
through 7 (or 2 through 5, etc.). The use of non-contiguous slots such as 0,
2, 4, and 6, for
example, may be less desirable. Figure 11 illustrates four slots (4-7) being
used and four
contiguous slots (0-3) being empty in a GSM frame.
It has been found experimentally, according to these embodiments of the
invention,
that GPS receivers can perform significantly better when the interval between
interference
bursts is increased or maximized. Without being bound by any theory of
operation, this
effect may be due to the relationship between the code repetition period of
the GPS C/A code
(1 msec.) and the GSM burst duration (about 0.577 msec.). With a GSM frame
occupancy
comprising alternate slots, each GPS signal code period can experience at
least one "hit",
whereas a GSM frame occupancy comprising four to five contiguous slots allows
the GPS
receiver to derive sufficient clean information, so as to "flywheel" through
the error events.
According to other embodiments of the invention, embodiments of Figures 8-10
can
be combined with embodiments of Figure 11. Furthermore, according to other
embodiments
of the invention, if an fj carrier of Figures 9 or 10 is underutilized,
because of the relatively
small footprint of the inner-most region of the cell, it may be used to
support additional
traffic over the much larger outermost region of the cell.
Thus, for example, assume that only the first four slots in each frame of fj
are being
used for inner region traffic. In embodiments of Figures 8-10, these four fj
slots are carrying
relatively low power bursts, for example of the order of 100 mW or less, and
may, therefore,
appear as (almost) unoccupied from an interference point of view. Loading the
remaining
four (contiguous) time slots of fj with relatively high-power bursts may have
negligible effect
on a GPS receiver because the GPS receiver would continue to operate reliably
based on the
benign contiguous time interval occupied by the four low-power GSM bursts.
Figure 12
illustrates embodiments of a frame at carrier fi supporting four low-power
(inner interval)
users and four high-power (outer interval) users. In fact, embodiments
illustrated in Figure
12 may be a preferred strategy for the set of available carrier frequencies
that are closest to
the GPS band. These embodiments may avoid undue capacity loss by more fully
loading the
carrier frequencies.
The experimental finding that interference from GSM carriers can be relatively
benign to GPS receivers provided that no more than, for example, 5 slots per 8
slot GSM
frame are used in a contiguous fashion can be very useful. It can be
particularly useful since
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this experimental finding may hold even when the GSM carrier frequency is
brought very
close to the GPS band (as close as 1558.5 MHz) and the power level is set
relatively high.
For example, with five contiguous time slots per frame populated, the worst-
case measured
GPS receiver may attain at least 30 dB of desensitization margin, over the
entire ATC service
area, even when the ATC is radiating at 1558.5 MHz. With four contiguous time
slots per
frame populated, an additional 10 dB desensitization margin may be gained for
a total of 40
dB for the worst-case measured GPS receiver, even when the ATC is radiating at
1558.5
MHz.
There still may be concern about the potential loss in network capacity
(especially in
data mode) that may be incurred over the frequency interval where embodiments
of Figure 11
are used to underpopulate the frame. Moreover, even though embodiments of
Figure 12 can
avoid capacity loss by fully loading the carrier, they may do so subject to
the constraint of
filling up the frame with both low-power and high-power users. Moreover, if
forward link
carriers are limited to 5 contiguous high power slots per frame, the maximum
forward link
data rate per carrier that may be aimed at a particular user may become
proportionately less.
Therefore, in other embodiments, carriers which are subject to contiguous
empty/low
power slots are not used for the forward link. Instead, they are used for the
return link.
Consequently, in some embodiments, at least part of the ATC is configured in
reverse
frequency mode compared to the SBC in order to allow maximum data rates over
the forward
link throughout the entire network. On the reverse frequency return link, a
radiotelephone
may be limited to a maximum of 5 slots per frame, which can be adequate for
the return link.
Whether the five available time slots per frame, on a reverse frequency return
link carrier, are
assigned to one radiotelephone or to five different radiotelephones, they can
be assigned
contiguously in these embodiments. As was described in connection with Figure
12, these
five contiguous slots can be assigned to high-power users while the remaining
three slots may
be used to serve low-power users.
Other embodiments may be based on operating the ATC entirely in reverse
frequency
mode compared to the SBC. In these embodiments, an ATC transmits over the
satellite
return link frequencies while radiotelephones respond over the satellite
forward link
frequencies. If sufficient contiguous spectrum exists to support CDMA
technologies, and in
particular the emerging Wideband-CDMA 3G standard, the ATC forward link can be
based
on Wideband-CDMA to increase or maximize data throughput capabilities.
Interference with
GPS may not be an issue since the ATCs transmit over the satellite return link
in these
embodiments. Instead, interference may become a concern for the
radiotelephones. Based,
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however, on embodiments of Figures 11-12, the radiotelephones can be
configured to
transmit GSM since ATC return link rates are expected, in any event, to be
lower than those
of the forward link. Accordingly, the ATC return link may employ GPRS-based
data modes,
possibly even EDGE. Thus, return link carriers that fall within a
predetermined frequency
5 interval from the GPS band-edge of 1559 MHz, can be under loaded, per
embodiments of
Figures 11 or 12, to satisfy GPS interference concerns.
Finally, other embodiments may use a partial or total reverse frequency mode
and
may use CDMA on both forward and return links. In these embodiments, the ATC
forward
link to the radiotelephones utilizes the frequencies of the satellite return
link (1626.5 MHz to
10 1660.5 MHz) whereas the ATC return link from the radiotelephones uses
the frequencies of
the satellite forward link (1525 MHz to 1559 MHz). The ATC forward link can be
based on
an existing or developing CDMA technology (e.g., IS-95, Wideband-CDMA, etc.).
The ATC
network return link can also be based on an existing or developing CDMA
technology
provided that the radiotelephone's output is gated to cease transmissions for
approximately 3
15 msec once every T msec. In some embodiments, T will be greater than or
equal to 6 msec.
This gating may not be needed for ATC return link carriers at approximately
1550
MHz or below. This gating can reduce or minimize out-of-band interference
(desensitization) effects for GPS receivers in the vicinity of an ATC. To
increase the benefit
to GPS, the gating between all radiotelephones over an entire ATC service area
can be
20 substantially synchronized. Additional benefit to GPS may be derived
from system-wide
synchronization of gating. The ATCs can instruct all active radiotelephones
regarding the
gating epoch. All ATCs can be mutually synchronized via GPS.
Multi-Band/Multi-Mode Satellite Radiotelephone Communications Systems and
Methods
Some embodiments of the present invention that were described above may use
the
same satellite radiotelephone link band and satellite feeder link band for
space-based
communications with radiotelephones in all satellite cells of the satellite
footprint or service
area. Moreover, some embodiments of the present invention that were described
above may
use the same satellite radio frequency band and substantially the same air
interface for
terrestrial communications with radiotelephones using an ancillary terrestrial
network. Other
embodiments of the present invention that will now be described may use more
than one
band and/or more than one air interface in various satellite cells in the
satellite footprint or
service area. In still other embodiments, although different bands and/or
different air
interfaces may be used in different satellite cells or within a satellite
cell, the satellite
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radiotelephone frequency band and the air interface that is used for
terrestrial
communications between an ancillary terrestrial network and radiotelephones
within a given
satellite cell, is substantially the same as is used for space-based
communications with the
radiotelephones within the given satellite cell or in different satellite
cells.
As used herein, "substantially the same" band means that the bands
substantially
overlap, but that there may be some areas of non-overlap, for example at the
band ends.
Moreover, "substantially the same" air interface means that the air interfaces
are similar but
need not be identical. Some changes may be made to the air interface to
account for different
characteristics for the terrestrial and satellite environments. For example, a
different vocoder
rate may be used (for example, 13kbps for GSM and 4kbps for satellite), a
different forward
error correction coding and/or a different interleaving depth may be used.
Multi-band/multi-mode satellite radiotelephone communications systems and
methods
according to some embodiments of the present invention may be used when a
satellite
footprint or service area spans a geographic area in which two or more
terrestrial
radiotelephone systems (wireless network operators) are present, to add spaced-
based
communications capability to two or more terrestrial networks. Within a
geographic area that
is covered by a given terrestrial radiotelephone system, embodiments of the
invention can
provide additional capacity and/or extended services using the space-based
component and/or
the ancillary terrestrial network, using substantially the same band and/or
air interface as the
terrestrial radiotelephone system. Thus, different geographic regions
corresponding to
different terrestrial radiotelephone communications systems and methods
according to
embodiments of the invention may use different bands and/or air interfaces for
compatibility
with the terrestrial radiotelephone systems that are located within the
different geographic
areas. There also may be other scenarios wherein it may be desired for a
single satellite
radiotelephone communications system/method to employ different bands and/or
air
interfaces over the same and/or different geographic regions thereof.
Figure 16 is a schematic diagram of satellite radiotelephone systems and
methods
according to some embodiments of the invention. As shown in Figure 16, these
embodiments
of satellite radiotelephone systems and methods include a space-based
component 1610 that
is configured to communicate with radiotelephones 1620a-1620c in a satellite
footprint 1630
that is divided into a plurality of satellite cells 1640a-1640c. It will be
understood by those
having skill in the art that, although three satellite cells 1640a-1640c and
three
radiotelephones 1620a-1620c are illustrated in Figure 16, satellite
radiotelephone systems
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and methods according to embodiments of the present invention may employ more
than three
satellite cells 1640a-1640c and may employ more than three radiotelephones
1620a-1620c.
Still referring to Figure 16, the space-based component 1610 is configured to
communicate with a first radiotelephone 1620a in a first satellite cell 1640a
over a first
frequency band and/or a first air interface, and to communicate with a second
radiotelephone
1620b in a second satellite cell 1640b over a second frequency band and/or a
second air
interface. In other embodiments, the first radiotelephone 1620a and the second
radiotelephone 1620b may be in the same satellite cell.
Still referring to Figure 16, in some embodiments of the present invention, an
ancillary terrestrial network 1650 is configured to communicate terrestrially
with the first
radiotelephone 1620a over substantially the first frequency band and/or
substantially the first
air interface, and to communicate terrestrially with the second radiotelephone
1620b over
substantially the second frequency band and/or substantially the second air
interface. These
substantially the same first frequency band and/or first interface in the
first satellite cell
1640a and in the portion of the ancillary terrestrial network 1650 therein, is
illustrated by the
vertical dashed lines that cover the first satellite cell 1640a and the
portion of the ancillary
terrestrial network 1650 therein. The substantially the same second frequency
band and/or
second air interface in satellite cell 1640b and in the portion of the
ancillary terrestrial
network 1650 therein, is illustrated by the horizontal dashed lines that cover
the second
satellite cell 1640b and the portion of the ancillary terrestrial network 1650
therein.
It will be understood that in Figure 16, the ancillary terrestrial network
1650 is
illustrated as including a small number of ancillary terrestrial network cells
for simplicity.
However, more ancillary terrestrial network cells may be present in some
embodiments of the
present invention. Moreover, it also will be understood that, in some
embodiments, a first
portion of the ancillary terrestrial network 1650 within satellite cell 1640a
may be operated
by a first wireless network operator and a second portion of the ancillary
terrestrial network
1650 within the first satellite cell 1640a or within the second satellite cell
1640b may be
operated by a second wireless network operator. Accordingly, some embodiments
of the
invention provide systems and methods for adding space-based communications to
first and
second terrestrial networks.
Referring again to Figure 16, satellite radiotelephone systems and methods
according
to some embodiments of the present invention also include a gateway 1660 that
is configured
to communicate with the space-based component 1610 over a feeder link 1670.
The feeder
link 1670 is configured to transport communications between the space-based
component
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1610 and the first and second radiotelephones 1620a, 1620b. In some
embodiments, the
feeder link 1670 comprises the first air interface and the second air
interface. Finally, it also
will be understood that a third satellite cell 1640c, a third radiotelephone
1620c, and a
substantially the same third frequency band and/or air interface is
illustrated by oblique
dashed lines in satellite cell 1640c. In other embodiments, the third
radiotelephone 1620c is
in the same cell as the first radiotelephone 1620a and/or the second
radiotelephone 1620b.
Figure 17 is a schematic diagram of satellite radiotelephone systems and
methods
according to other embodiments of the present invention. As shown in Figure
17, a space-
based component 1710 is configured to communicate with a first radiotelephone
1720a over
a first frequency band and/or first air interface 1780a, also designated in
Figure 17 by F1/11.
As also shown in Figure 17, the space-based component 1710 is also configured
to
communicate with a second radiotelephone 1720b over a second frequency band
and/or a
second air interface 1780b, also designated in Figure 17 by F2/I2. An
ancillary terrestrial
network 1750 is configured to communicate terrestrially with the first
radiotelephone 1720a
over substantially the first frequency band and/or substantially the first air
interface 1790a,
also designated in Figure 17 as F1'/11', and to communicate terrestrially with
the second
radiotelephone 1720b over substantially the second frequency band and/or
substantially the
second air interface 1790b, also designated in Figure 17 as F2'/12'. The
ancillary terrestrial
network 1750 may be included within a single satellite cell or may spread
across multiple
satellite cells.
As also shown in Figure 17, the ancillary terrestrial network can comprise a
first
ancillary terrestrial component 1752a that is configured to communicate
terrestrially with the
first radiotelephone 1720a over substantially the first frequency band and/or
substantially the
first air interface 1790a. A second ancillary terrestrial component 1752b is
configured to
communicate terrestrially with the second radiotelephone 1720b over
substantially the second
frequency band and/or substantially the second air interface 1790b. As was the
case in
Figure 16, a large number of radiotelephones 1720 and/or ancillary terrestrial
components
1752 may be provided in some embodiments. The first and second ancillary
terrestrial
components 1752a, 1752b, respectively, may be parts of two separate wireless
networks in
the same and/or different satellite cells, in some embodiments. Thus, some
embodiments of
Figure 17 provide systems and methods for adding space-based communications to
first and
second terrestrial networks. A gateway 1760 and a feeder link 1770 may be
provided, as was
described in connection with Figure 16.
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Some embodiments of the present invention provide satellite radiotelephone
systems
and/or methods that include radiotelephone links that are operative over a
plurality of bands.
In some embodiments, the band-sensitive (i.e., frequency-sensitive) components
of the space-
based component 1610, 1710, such as the antenna feed network, the power
amplifiers, the
low noise amplifiers, etc., may be designed to be broadband, so that the
operational range of
the space-based component can extend over a plurality of service link bands,
such as L-band,
S-band, etc. In other embodiments, separate components for each band may be
provided. In
still other embodiments, some common broadband components and some separate
narrowband components may be provided.
Moreover, other embodiments of the present invention may provide a multi-mode
payload capacity, by providing a plurality of air interfaces that may be used
to provide
radiotelephone communications with the space-based component 1610, 1710 and a
plurality
of radiotelephones 1620, 1720 in a satellite footprint over the same and/or a
plurality of
satellite cells. The space-based component 1610, 1710 may be configured to
support a
plurality of air interface standards, for example by having a programmable
channel increment
that can be responsive to ground commands. Different channel increments, for
example, may
be applied by the space-based components 1620, 1720 to different bands of the
received
feeder link signal 1670, 1770 from a gateway 1660, 1760. These different bands
of the
feeder link spectrum may remain constant or may change with time, depending on
the traffic
carried by each air interface standard that may be supported by the satellite
radiotelephone
system.
Thus, in some embodiments, the feeder link 1670, 1770 may be segmented into
bands, such as bands B1, B2 and B3. In one example, band B1 can transport GSM
carriers
between the gateway and the space-based component, band B2 can transport
narrowband
CDMA carriers and band B3 may transport wideband CDMA carriers. It will be
understood
by those having skill in the art that corresponding return feeder link bands
may be provided
for carriers from the space-based component 1610, 1710 to the gateway 1660,
1760. In other
embodiments of the present invention, an ancillary terrestrial network 1650,
1750 also may
be provided to corrununicate terrestrially with radiotelephones 1620, 1720 in
the satellite
footprint. Thus, in some embodiments, the ancillary terrestrial network 1650,
1750 may
provide a larger portion of the radiotelephone communications in urban areas,
whereas the
space-based component 1610, 1710 may provide a larger portion of the
radiotelephone
communications in rural areas.
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Figure 13 is a block diagram of satellite radiotelephone systems and/or
methods that
can use multiple bands and/or multiple modes according to some embodiments of
the present
invention. It will be understood by those having skill in the art that Figure
13 relates to GSM,
and system elements that provide a GSM air interface are shown. However, other
satellite
5 radiotelephone systems and/or methods also may be provided according to
embodiments of
the present invention.
In particular, as shown in Figure 13, these embodiments of satellite
radiotelephone
communication systems and methods include a space-based component 1310, for
example a
geostationary satellite, and at least one Gateway Station System (GSS) 1360,
Network
10 Operation Center (NOC) 1362, Mobile Switching Center (MSC) 1364, Base
Station
Controller (BSC) 1366 and Base Transceiver Station (BTS) 1368. The satellite
radiotelephone system may be connected to the Public Switched Telephone
Network (PSTN)
1772 and/or to one or more Public Data Networks (PDN) 1774. In addition, to
offer a
General Packet Radio Service (GPRS), some MSCs 1364 may be augmented by
appropriate
15 packet switching facilities, generally referred to as Support GPRS
Service Node (SGSN) and
GPRS Gateway Support Node (GGSN). The GSS also may be connected to a Tracking
Telemetry & Command (TT&C) system 1776. A plurality of radiotelephones 1320
also may
be provided.
Figure 14 illustrates frequency reuse between a space-based component and an
20 ancillary terrestrial network according to some embodiments of the
present invention. As
shown in Figure 14, relatively small ancillary terrestrial network cells 1450
are nested inside
the relatively large satellite cells 1440. This may occur because, even with
large reflectors
that may be used in the space-based component 1410, the satellite cells 1440
may still be on
the order of several hundred kilometers in diameter, whereas the ancillary
terrestrial network
25 cells 1450 may be two, three or more orders of magnitude smaller than
the satellite cells. In
Figure 14, terrestrial reuse of the same carrier frequency is indicated by the
same symbol (, o
or *).
Embodiments of the present invention as shown in Figures 13 and 14 can allow a
single satellite radiotelephone system to support a plurality of ancillary
terrestrial components
1452 in an ancillary terrestrial network 1450, with at least some of the
ancillary terrestrial
components 1452 providing terrestrial connectivity via a different air
interface. This may
allow the relatively large satellite footprint 1430 to be used in a
terrestrial market which is
segmented. Thus, in some embodiments, the satellite radiotelephone system may
be
configured to support a GSM-based ancillary terrestrial component, a
narrowband CDMA-
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based ancillary terrestrial component, and a wideband CDMA-based ancillary
terrestrial
component, at the same time and over the same or different satellite cells. In
other
embodiments, a subset of the ancillary terrestrial components may be operating
at L-band, for
example, while another subset of ancillary terrestrial components may be
operating at S-band.
As was already described, in some embodiments, satellite radiotelephone
communications systems and methods can provide substantially the same
band/same air
interface service for both space-based communications with the space-based
component and
terrestrial communications with at least one of its ancillary terrestrial
components. This can
allow simplified radiotelephones.
In particular, Figure 15 is a block diagram of radiotelephones 1520 that may
be used
to communicate with a space-based component and an ancillary terrestrial
component in
satellite radiotelephone systems or methods according to some embodiments of
the present
invention. In some embodiments, these radiotelephones 1520 can be used with
satellite
radiotelephone systems according to some embodiments of the present invention
that include
an ancillary terrestrial component and a space-based component that use
substantially the
same band and substantially the same air interface. The ability to reuse the
same spectrum
for space-based and terrestrial communications can facilitate low cost, small
and/or
lightweight radiotelephones, according to some embodiments of the present
invention.
Moreover, some embodiments of the present invention can place more of the
burden
of link performance with the space-based component rather than the
radiotelephone,
compared to prior satellite radiotelephone systems, such as Iridium or
Globalstar.
Accordingly, large antennas may not need to be used in the radiotelephone.
Rather, antennas
that are similar to conventional cellular radiotelephone antennas may be used.
Accordingly, referring to Figure 15, a single Radio Frequency (RF) chain
including
low pass filters 1522, up and down converters 1524a, 1524b, Local Oscillators
(LO) 1526,
Low Noise Amplifier (LNA) 1528, Power Amplifier (PA) 1532, bandpass filters
1534 and
antenna 1536, may be used. A single baseband processor 1542 may be used,
including an
analog-to-digital converter (A/D) 1544, a digital-to-analog converter (D/A)
1546 and a Man-
Machine Interface (MMI) 1548. An optional Bluetooth interface 1552 may be
provided. An
Application-Specific Integrated Circuit (ASIC) 1554 may include thereon Random
Access
Memory (RAM) 1556, Read-Only Memory (ROM) 1558, a microprocessor (IR) 1562,
logic
for ancillary terrestrial communications (ATC Logic) 1564 and logic for space-
based
communications (Space Segment Logic or SS Logic) 1566. The SS Logic 1566 can
be used
to accommodate satellite-unique requirements over and above those of cellular
or PCS, such
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as a satellite-unique vocoder, a satellite forward error correction coding
scheme, a satellite-
unique interlever, etc. However, this added gate count may not increase the
cost of the ASIC
1554.
According to other embodiments of the invention, the space-based component may
be
dimensioned appropriately, so that there is no need for radiotelephones to use
large antennas
1536 or to have to radiate any more power when in satellite mode than when in
terrestrial
mode. An appropriate level of link robustness may be attained via the spot-
beam gain that
can be provided by a larger satellite antenna and/or other techniques. This
can more than
compensate for the several dB reduction in satellite link robustness that may
occur when
eliminating a large satellite antenna from the radiotelephone and/or using a
single antenna for
terrestrial and satellite communications. Accordingly, single mode and single
band
radiotelephones may be provided that can communicate with the space-based
component and
the ancillary terrestrial network over a single band and single air interface.
Aggregate Radiated Power Control for Multi-Band/Multi-Mode Satellite
Radiotelephone
Communications Systems and Methods
Multi-band/multi-mode satellite radiotelephone communications systems and
methods
according to other embodiments of the present invention now will be described.
In particular, referring to Figure 18, a satellite radiotelephone system
includes a
space-based component 1610 that is configured to communicate with a plurality
of
radiotelephones over a plurality of frequency bands and/or a plurality of air
interfaces. The
links that use the plurality of frequency bands and/or air interfaces are
denoted in Figure 18
as 1880a-1880f, although it will be understood that fewer or more frequency
bands/air
interfaces may be used. An ancillary terrestrial network (ATN) 1850 is
configured to
communicate terrestrially with the plurality of radiotelephones over
substantially the plurality
' of frequency bands and/or substantially the plurality of air interfaces.
It will be understood
that, in Figure 18, five ancillary terrestrial components (ATC) 1852a-1852f
are shown,
although fewer or more ancillary terrestrial components may be employed in the
ancillary
terrestrial network 1850. A satellite gateway 1660 and a PDN/PSTN 1810 are
also provided
as was already described.
Still referring to Figure 18, an aggregate radiated power controller 1820 is
provided
that is configured to limit an aggregate radiated power by the plurality of
radiotelephones to a
maximum aggregate radiated power. In some embodiments, the aggregate radiated
power
controller is configured to control a plurality of co-frequency
radiotelephones, so as to limit
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the aggregate radiated power by the plurality of co-frequency radiotelephones
to a maximum
aggregate radiated power. As used herein, "co-frequency" means that the
radiotelephones use
the same carrier frequency even if they use different TDMA time slots
(different TDMA
channels) or use different CDMA spreading codes (different CDMA channels).
Accordingly,
compliance with radiation requirements for the ancillary terrestrial network
1850 may be
maintained even though the ancillary terrestrial network 1850 employs a
plurality of
frequency bands and/or air interfaces. It will be understood that the
aggregate radiated power
controller 1820 may be provided as a stand alone component, as part of the
gateway 1660,
and/or as part of another component of the satellite radiotelephone system
and/or the ATN.
In some embodiments of the present invention, the aggregate radiated power
controller 1820 is configured to allow control over substantially all of the
ATN and/or
substantially all of the radiotelephones that are communicating therewith.
However, in other
embodiments of the present invention, the aggregate radiated power controller
1820 is
configured to limit an aggregated radiated power by a subset of the plurality
of
radiotelephones to a maximum aggregate radiated power. For example, in some
embodiments, the plurality of frequency bands comprises a first frequency band
and a second
frequency band, and the subset of the plurality of radiotelephones comprises
radiotelephones
that communicate terrestrially with the ancillary terrestrial network over
substantially the first
frequency band. In some embodiments, the first frequency band comprises L-band
frequencies and, in some embodiments, the second frequency band comprises S-
band
frequencies. In other embodiments, the first frequency band comprises L-band
frequencies
that are used substantially inter-radio-horizon by another system and the
second frequency
band comprises L-band frequencies that are not used substantially inter-radio-
horizon by
another system. In these embodiments, the second frequency band may further
comprise S-
band frequencies.
Thus, in some embodiments, only a first subset of the ATN, and/or the
radiotelephones communicating therewith, may be subject to aggregate radiated
power
control, whereas a second subset of the ATN, and/or the radiotelephones that
are
communicating therewith, need not be subject to aggregate radiated power
control. For
example, L-band frequencies that are radiated terrestrially may potentially
cause interference
with another system, and may be subject to aggregate radiated power control.
In contrast, S-
band frequencies and L-band frequencies that are not used substantially inter-
radio-horizon
by another system may not potentially cause interference with another system,
and therefore
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29
may not be subject to aggregate radiated power control, according to
embodiments of the
present invention.
More specifically, a Mobile Satellite System (MSS) including an ATN 1850 may
provide voice and/or data services to end users over its footprint using more
than one air
interface protocol. It may be desirable for the system to be capable of
providing services to
end users via several air interface protocols given the current fragmentation
and potential
future uncertainty of the U.S. radiotelephone communications market.
Currently, the U.S.
market may be serviced by iDEN, GSM and cdma2000, but other emerging
standards, such
as W-CDMA and/or OFDM/OFDMA, may be used in the future. A system architecture
that
lends itself to the plurality of current standards (air interface protocols)
and can also
accommodate future (currently anticipated or not) technologies can offer
increased flexibility.
Figure 18 illustrates a potential deployment scenario for the ATN. As shown,
different and/or overlapping geographical areas may be served by ATCs 1852a-
1852f that are
using different air interface protocols. The satellite 1610 is capable of
transporting the
plurality of protocols to/from the satellite gateway 1660 where different sets
of transceiver
units may be associated with the processing of the different air interface
waveforms. The
radiotelephone may contain an integrated transceiver capable of communicating
via the
satellite 1610 or via at least one ATC 1852, and potentially over other
PCS/cellular bands,
depending, for example, on business relationships that may be established with
other wireless
operators. The satellite/ATN part of the radiotelephone transceiver may
utilize substantially
the same air interface protocol to communicate via the satellite 1610 or via
at least one ATC
1852. This approach can reduce or minimize the size, weight and/or
manufacturing cost of
the transceiver by increasing the level of integration and reuse of hardware
and software for
both satellite and ATN modes.
In some embodiments of the invention, the ATN may be based on a CDMA air
interface protocol without producing any greater interference potential than
the Federal
Communications Commission rules allow for a GSM-based ATN. See, Report and
Order
and Notice of Proposed Rulemaking, FCC 03-15, Flexibility for Delivery of
Communications
by Mobile Satellite Service Providers in the 2 GHz Band, the L-Band, and the
1.6/2.4 Bands,
IB Docket No. 01-185, Adopted: January 29, 2003, Released: February 10, 2003,
hereinafter
referred to as "FCC 03-15". Thus, the technology used by the ATN or any of its
ATCs can be
irrelevant as long as the aggregate co-frequency emissions level is controlled
so as not to
exceed the limit set forth by the Commission for the specific GSM system
considered in FCC
03-15. As such, an ATN 1850 can be developed to function with a plurality of
air interface
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protocols simultaneously, as long as it adheres to the aggregate radiated
power spectral
density limit set forth by the Commission (i.e., -53 + 10log(1,725) dBW/Hz).
In FCC 03-15, the Commission allowed 1,725-fold terrestrial reuse, by the US
ATN,
of a GSM carrier that is also used by the MSS for satellite communications. A
single fully-
5 loaded GSM carrier on an ATC return link, which is being radiated from
several
radiotelephones (up to eight) to a base station, may launch a maximum -53
dBW/Hz of power
spectral density into space. The maximum aggregate power spectral density that
may be
launched into space from 1,725 co-channel fully loaded return-link GSM
carriers is,
therefore, -53 + 10log (1725) -20.64 dBW/Hz. This is based on a GSM
radiotelephone
10 peak EIRP ofO dBW, consistent with the analysis of FCC 03-15. It is this
maximum
aggregate power spectral density, produced on the return link by the maximum
allowed US-
wide frequency reuse of the ATN, that the Commission has concluded may
potentially raise
the noise floor of Inmarsat's satellite receivers by as much as 0.7%.
The maximum EIRP of a CDMA return link code (user) may be -10 dBW and may be
15 transmitted over a carrier occupying a bandwidth of 1.25 MHz in
accordance, for example,
with the cdma2000 air interface standard. Thus, -10 ¨ 10log(1,250,000) -70.97
dBW/Hz
of power spectral density may be launched into space by a single CDMA code
(user)
operating on an ATC return link. The allowed -20.64 dBW[Hz maximum aggregate
power
spectral density limit, as derived above, may therefore accommodate
approximately
.70 10[(70.97 -20 64)/10] 107,894 co-channel return link CDMA codes. This
result may be used to
establish an equivalence relation, for the ATN return link, between a pure GSM
ATN and a
pure CDMA ATN.
Thus, from an aggregate return link interference power spectral density
standpoint,
1,725-fold US-wide frequency reuse of a GSM carrier by the ATN may be
considered
25 equivalent to approximately 107,894 codes (users) transmitting US-wide
on a given 1.25
MHz CDMA carrier. The number of users is generally less than or equal to the
number of
codes, because a user may be allocated more than one code to improve the
reliability and/or
data rate of transmission. The stated equivalence is based on GSM's peak
return link EIRP
assumed to be 0 dBW while that of a CDMA code is assumed to be -10 dBW.
30 A mathematical equivalence may be established between a single active
(transmitting)
GSM time slot (user) transmitting at a peak EIRP of 0 dBW, and a number of
CDMA codes
(users) being active and each transmitting at a peak EIRP of -10 dBW. This
relationship can
allow deploying an ATN that contains both GSM and CDMA technologies, and
potentially
fluctuating capacity between the two, and is, from the point of view of
aggregate return link
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interference power spectral density potential, equivalent to the pure GSM
system that the
Commission addressed in FCC 03-15.
In particular, according to FCC 03-15, there are 1,725 x 8 = 13,800 GSM time
slots
(users) that can be active on the ATN (US-wide) on a given GSM carrier while
maintaining
the potential for noise increase to Inmarsat's satellite receivers at 0.7%. It
was shown above
that, from an aggregate up-link power spectral density interference potential
standpoint, this
is equivalent to approximately 107,894 codes (users) transmitting on a given
1.25 MHz
CDMA carrier (US-wide). Thus, one active co-frequency GSM slot (user) equates
to
approximately 107,894/13,800 7.8184 active co-frequency CDMA codes (users).
Thus, an
equation that may be used to govern co-frequency ATN operations over the
United States
may be:
NGsm 13,800NcumA/107,894 = 13,800. (1)
In Equation (1), NGsm denotes the number of active co-frequency GSM time slots
(users) while NcDmA denotes the number of active co-frequency CDMA codes
(users). In
some embodiments, the NGsm GSM time slots are at least partially co-frequency
with the
NCDMA CDMA codes. Since there are 6 distinct GSM carriers that can be co-
frequency with
a single CDMA carrier of 1.25 MHz bandwidth, the co-frequency CDMA carrier
loading will
deplete, by the same amount of 13,800NcomA/107,894, the US-wide capacity of
all 6
corresponding (co-frequency with the CDMA carrier) GSM carriers. Based on the
above, it
is seen that a US-wide ATN network that is configured to support
simultaneously both GSM
and cdma2000 traffic can be compliant with the Commission's uplink
interference constraint
(no more than 0.7% AT/T impact to, for example, Inmarsat) if and only if
Equation (1) is
substantially satisfied. The MSS/ATN operator may comply by apportioning the
total co-
frequency traffic in such an ATN substantially in accordance with Equation
(1).
As discussed earlier, a fully-loaded GSM return link carrier (all eight time
slots
occupied) may generate -53 dBW/Hz of maximum EIRP density potential. This
result is
based on GSM radiotelephones/radioterminals having an antenna gain of, for
example, 0 dBi
and radiating a maximum 0 dBW EIRP over a carrier bandwidth of 200 kHz (in
accordance
with the FCC's assumptions in FCC 03-15.
A cdma2000 ATN radiotenninal having, for example, a 0 dBi antenna gain may be
limited (by design) to a maximum of, for example, -9 dBW EIRP while
communicating using
a single code. Given the 1.25 MHz carrier bandwidth of cdma2000 (1xRTT) the
maximum
EIRP density that may be generated by a single cdma2000 return-link code may
be
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-9 -10log(1.25 x 106) -70 dBW/Hz. It therefore follows that 10[(7 - 53)/10] 50
co-frequency
cdma2000 codes may generate the same uplink interference power spectral
density potential
as one fully-loaded GSM carrier.
For W-CDMA, an ATN radioterminal having, for example, a 0 dBi antenna gain may
be limited (by design) to a maximum of, for example, -9 dBW EIRP while
communicating
using a single code. Given the 5 MHz carrier bandwidth of W-CDMA, such a
radioterminal
may generate an EIRP density potential of -9 -10log(5 x 106) -76 dBW/Hz. Thus,
{(76 53)/10] 200 co-frequency W-CDMA codes may generate the same uplink
interference
power spectral density potential as one fully-loaded GSM carrier.
10 For an ATN that may be based on all three technologies (GSM, cdma2000,
and W-
CDMA) the following constraint equation may be used to specify the allowed
distribution of
on-the-air co-frequency traffic associated with the three standards:
N/8 + M/50 + L/200 = R (2)
where N denotes the number of GSM time slots (channels) supported ATN-wide co-
frequency by a given GSM carrier as that carrier is used and reused, M
represents the number
of cdma2000 co-frequency codes (channels) supported by a single cdma2000
carrier as that
carrier is used and reused throughout the ATN, L identifies the number of W-
CDMA co-
frequency codes (channels) on a single W-CDMA carrier as that carrier is used
and reused by
the ATN, and R denotes the pure GSM-based ATN frequency reuse authorized by
the FCC.
In some embodiments, the N GSM time slots, the M cdma2000 codes and the L W-
CDMA
codes are at least partially co-frequency. Note that the above equation can
provide a
constraint that may be imposed on co-frequency operating carriers (all three
carrier types,
GSM, cdma2000, and W-CDMA, whose ATN-wide traffic is apportioned in accordance
with
the above equation may be operating co-frequency). Furthermore, for a pure GSM-
based
ATN deployment, the above equation reduces to N = 8R (M = L = 0) which
confirms that the
total number of time slots (channels) that can be supported by a single GSM
carrier ATN-
wide equals eight times the authorized frequency reuse.
Since there are 6 GSM carriers that may fit within the bandwidth occupied by a
single
cdma2000 carrier, the nationwide loading (M) of a cdma2000 carrier may
deplete, by the
same amount of M/50, the nationwide capacity of all 6 corresponding (co-
frequency with the
cdma2000 carrier) GSM carriers. Similarly, since there are 25 GSM carriers
that may exist
within the bandwidth occupied by a single W-CDMA carrier, the nationwide
loading (L) of a
W-CDMA carrier may deplete, by the same amount of L/200, the nationwide
capacity of all
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25 corresponding (co-frequency with the W-CDMA carrier) GSM carriers. For
similar
reasons, since there are 4 cdma2000 carriers that may be accommodated (co-
frequency) over
the band of frequencies occupied by a W-CDMA carrier, the nationwide loading
of a W-
CDMA carrier may deplete, by the same amount of L/4, the nationwide capacity
of all 4
corresponding (co-frequency with the W-CDMA carrier) cdma2000 carriers.
Equations (1) and (2) may be generalized as follows:
E ____________________________ =MARP, (3)
where N1 is the number of co-frequency active users using a given frequency
band and/or air interface i;
Fi is a corresponding equivalence factor (which may be less than, greater than
or equal to 1) for the given frequency band/air interface i; and
MARP is a measure of the maximum aggregate radiated power spectral
density that is pemiitted.
It will be understood that in FCC 03-15, the aggregate radiated Power Spectral
Density (PSD) that may be launched U.S.-wide by radioterrninals communicating
with an
ATN may not exceed -53 + 10log(1725) -20.6 dBW/Hz. In arriving at this
conclusion the
FCC assumed that the ATN will be based on GSM technology and that the GSM
radioterminals will be capable of launching in the direction of a co-frequency
satellite system
(e.g., Inmarsat) a maximum (uplink) EIRP of 0 dBW per carrier. The FCC's
conclusion is
also based on the assurnption that only 50% of the ATN is inside the U.S.
The aggregate radiated U.S.-wide PSD may be higher if more than 50% of the ATN
is
allowed to be inside the U.S. For example, based on 80% deployment of the
total ATN
inside the US, the aggregate allowed US-wide PSD potential may grow to -53 +
10log(2760)
c---; -18.6 dBW/Hz. In FCC 03-15, the Commission concluded that the aggregate
average
signal attenuation that is relevant to uplink interference is 242.7 dB. This
number takes into
account attenuation/suppression of the interfering signal(s) due to (a) free-
space propagation
(188.7 dB), (b) co-frequency system satellite antenna discrimination in the
direction of the
ATN (25 dB), (c) outdoor blockage (3.1 dB), (d) closed-loop power control
implemented by
the ATN (20 dB), (e) use of a lower-rate vocoder (3.5 dB), (f) voice activity
(1 dB), and (g)
polarization discrimination provided by the co-frequency satellite system (1.4
dB). (See
FCC 03-15, Appendix C2, Table 2.1.1.C, page 206). The interference signal
suppression due
to power control (20 dB) comprises 2 dB due to "range taper" and 18 dB due to
structural
attenuation. Based on the Commission's conclusions/assumptions, as specified
in FCC 03-
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15, and assuming deployment of up to 80% of the ATN inside the US, the
aggregate average
PSD potential at the input of a co-frequency satellite antenna may be limited
to -18.6 ¨ 242.7
= -261.3 dBW/Hz.
As was described above, aggregated radiated power controlling systems and
methods
according to some embodiments of the present invention, may be configured to
limit an
aggregate radiated power by a plurality of radiotelephones to a maximum
aggregate radiated
power. In embodiments that were described above, it was assumed that the ATN
has the
same amount of structural attenuation margin and/or return link margin across
all ancillary
terrestrial components thereof, that use a given frequency band and/or carrier
frequency
and/or air interface. The calculations that were described above were made
under this
assumption. However, this may not always be the case. Rather, according to
other
embodiments of the present invention, various ATCs in the ATN may provide
different
structural attenuation and/or return link margins. In fact, according to other
embodiments of
the present invention, link margins may be increased in various ATCs, to allow
larger
numbers of radioterminals to communicate terrestrially without exceeding a
maximum
aggregate radiated power. Two illustrative examples will be provided. In a
first example, a
plurality of cdma2000 radioterminals communicate with ATN infrastructure that
provides 18
dB of structural attenuation margin. In a second example, not all of the ATN
infrastructure
provides 18 dB of structural attenuation margin.
Thus, in the first example, all cdma2000 ATC radioterminals communicate with
infrastructure that provides 18 dB of structural attenuation margin. Relative
to a satellite, a
cdma2000 ATN radioterminal may radiate, for example, a maximum (spatially
averaged)
EIRP of -13 dBW per communications channel (i.e., per code; the EIRP consumed
by the
pilot channel is neglected for the sake of simplicity). Hence, the
radioterminal's PSD
potential, per communications channel, may be -74 dBW/Hz (at the
radioteiminal's antenna
output) and -74 ¨ 242.7 = -316.7 dBW/Hz at the satellite's antenna input. The
number of
such radioterminals (communications channels) that operate co-frequency in
order to
generate the allowed PSD potential of -261.3 dBW/Hz, at the input of a
satellite antenna, is
1 0[(316.7 261.3)/10] = 346,736. In some embodiments, up to seven (7) cdma2000
carriers may be
deployed in the ATN. Thus, the total on-the-air capacity of a U.S.-based ATN
may be
346,736 x 7 = 2,427,152 simultaneous communications channels.
In the second example, not all radioterminals are communicating with
infrastructure
that provides 18 dB of structural attenuation margin. For example, let X, Y,
and Z denote
US-wide potential percentages (%) of ATN cdrna2000 radioterminals that may be
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communicating co-frequency with ATN infrastructure that is providing A, B, and
C dB,
respectively, of structural attenuation margin. Thus:
X+Y+Z=100. (4)
5
Letting L, M, and N denote the number of potential radioterminals that may be
communicating with class A, B, and C infrastructure, respectively, we may
write:
X = 100L/(L + M +N), Y = 100M/(L + M + N), Z = 100N/(L + M + N). (5)
Subject to the three classes/categories of ATN infrastructure (as defined
above) that may be
serving the ATN radioterminals, the aggregate power spectral density potential
(in Watts/Hz)
at a satellite antenna input may be:
psd = [1_4 +1Vg + Nc]o-2 Watts/Hz. (6)
In Equation (6), the quantity 101og(a2) may, for example, be specified as -74
dBW/Hz, and 4,
and g, may denote average aggregate (power-domain) attenuation factors
associated with
the three classes of radioterminals that may be served by the three classes of
infrastructure,
respectively. Thus, we may write:
101og() = -(188.7 + 25 + 3.1 + (A + 2) + 3.5 + 1 + 1.4) = -(224.7 + A) dB
(7)
101og() = -(188.7 + 25 + 3.1 + (B + 2) + 3.5 + 1 + 1.4) --- -(224.7 + B) dB;
and (8)
10log(c) = -(188.7 + 25 + 3.1 + (C + 2) + 3.5 + 1 + 1.4) = -(224.7 + C) dB.
(9)
Using Equation (5):
N = L[(100-X)(100-Y) ¨ XY]/100X, and M = 100YL/[(100-Y)(100-Z) ¨ YZ]. (10)
Substituting Equations (7) through (10) into Equation (6) and taking the
logarithm, the
average PSD potential at a victim satellite may be expressed as:
PSD 10log(psd) = 10log(o2) + 10log(L)
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+ 101og(10-(2247+ 0.1A) 1042247 + "13) X 1 00Y/R100-Y)(1 00-Z) ¨ YZ] (11)
+ 1 0(2147 0.1C) X R 00-X)(1 00-Y) ¨ XY]/1 00X)
or,
-261.3 = -74 + 101og(L)
+ 10log(1 0 0.1A) +42147 + 1
042147 + MB) X 100Y/[(100-Y)(100-Z) ¨ YZ] (12)
+ 1 022.47 + 0.1C) x [( 1 00-X)(100-Y) ¨ XY]/100X).
Solving for L:
L = 1 0-1833 log( )= (13)
In Equation 13, the second term of the exponent "log( )" is defined by
Equation (12). That
is:
log( ) log(10"(22A7 + 0.1A) + 1 0-(22.47 + 0.1B) X 1 00Y/[(1 0O-Y)(1 00 -Z) ¨
YZ] (14)
4_ 1 0-(22A7 + 0.1C) x [(100-X)(100-Y) ¨ XY]/100X).
Once L is found from Equation (13), N and M may be evaluated using Equations
(5) as
follows:
N = L[(100 ¨ X)(100 ¨ Y) ¨ XY]/100X, and M = Y(L + N)/(100 ¨ Y) (15)
The following Table provides illustrative numerical results:
Table
X(%)/ Y(%)/ Z(%)/ L M N L+M+N (L+M+N)x7
A(dB) B(dB) C(dB)
100/18 0/18 0/18 346,736 0 0 346,736
2,427,152
60/22 30/12 10/6 68,859 34,439 11,499 114,797 803,579
30/18 60/12 10/6 24,349 48,685 8,108 81,142 567,994
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Accordingly, the second example that was described above may provide
additional
embodiments of Equation (3), wherein N, denotes a number of co-frequency
channels that are
operative subject to a common (ith) structural attenuation margin for a given
frequency band
and/or carrier frequency and/or air interface, F, denotes a corresponding
equivalence factor,
which may be less than, greater than, or equal to 1, for the common (ith)
structural attenuation
margin for the given frequency band/carrier frequency/air interface, and MARP
is a measure
of the maximum aggregated radiated power, i.e., the maximum aggregate radiated
Power
Spectral Density (PSD).
In some embodiments of the invention, an ATN may be configured to maintain a
list
of infrastructure components (i.e., base stations and/or base station
groupings), and associate
with each infrastructure component a measure of Structural Attenuation Margin
(SAM).
Based on the registration procedure of radioterminals, and/or other means, the
ATN may also
be configured to have knowledge of the infrastructure component with which
each active (on-
the-air) radioterminal is communicating. Thus, the ATN may be configured to
associate a
SAM with each active radioterminal and may thus be configured to evaluate the
quantity
E,(psd)õ where psd denotes a power spectral density at a satellite and where
the summation
may be performed over an ensemble of active (on-the-air) radioterminals that
are operating
co-frequency in the ATN (i.e., are sharing in whole or in part an ATN band
and/or sub-band
of frequencies). In some embodiments of the invention, the quantity (psd), may
be evaluated
for the ith co-frequency radioterminal as:
(psd); = 10[1 g(P/Bw,)+1 g(a1)}, (16)
where the quantity 10log(pl) may denote a measure of the maximum EIRP in the
direction of
a satellite that may be generated by the ith active (on-the-air) radioterminal
(e.g., -4 dBW for
GSM, -13 dBW for cdma2000 and/or W-CDMA), BW, may denote a measure of the
bandwidth occupied by the carrier being radiated by the ith active
radioterminal (e.g., 200 kHz
for GSM, 1.25 MHz for cdma2000, and 5 MHz for W-CDMA), and 10log(ai) may
denote a
measure of aggregate signal attenuation that may exist between the ith
radioterminal and a
satellite.
The quantity 101og(a,) may further be expressed as 10log(a,) = -(L + SAM,) dB,
where L is defined as a measure of aggregate signal attenuation potential
comprising, for
example, (a) free-space propagation (i.e., 188.7 dB), (b) co-frequency
satellite antenna
discrimination (i.e., 25 dB), (c) outdoor blockage (i.e., 3.1 dB), (d) ATN
power control due to
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range taper (i.e., 2 dB), (e) effect of low-rate vocoder (i.e., 3.5 dB), (0
effect of voice activity
(i.e., 1 dB), and (g) polarization discrimination provided by co-frequency
satellite antenna
(i.e., 1.4 dB). (See FCC 03-15 Appendix C2, Table 2.1.1.C; page 206). SAM i
may denote a
measure of structural attenuation margin provided by the infrastructure
component (i.e., a
base station and/or a group of base stations) with which the ith active co-
frequency
radioteiminal is communicating. Typical values of SAM i may be, for example,
22 dB, 18
dB, 12 dB, and 6 dB, for dense-urban, urban, sub-urban, and rural
infrastructure components,
respectively.
Accordingly, in some embodiments of the present invention, the aggregate
radiated
power controller is configured to control a plurality of co-frequency
radioterminals, so as to
limit the aggregate radiated power by the plurality of radioterminals to a
maximum aggregate
radiated power according to:
E(psd), = MARP , (17)
where (psd)i is a measure of radiated power spectral density at a satellite
and MARP is a
measure of allowed maximum aggregate radiated power. In some embodiments, psd
is
determined according to (psd); = 1011 g(Pi/Bwi) log(a)];where 101og(pi)
denotes a measure of
maximum radiated power by the ith radioteiminal in a direction of a satellite,
BW; denotes a
bandwidth occupied by a carrier that is radiated by the ith radioterminal and
101og(cci) denotes
a measure of signal attenuation (in dB) between the ith radioterminal and the
satellite.
The ATN may evaluate the quantity Ei(psd)i, and/or another measure thereof, as
needed, and may, in response to the value of Ei(psd)i, and/or the value of the
other measure,
approaching, being equal to, or having exceeded a threshold value, control the
ancillary
terrestrial network and/or one or more of the radioterminals to limit the
aggregate radiated
power to a maximum aggregate radiated power.
Many techniques may be used to limit the aggregate radiated power. For
example, in
some embodiments, one or more co-frequency radioterminals may be commanded to
1)
utilize a lower-rate vocoder, and/or 2) to reduce the rate of information
transmission, and/or
3) to use other available ATN or non-ATN resources that may not be co-
frequency with the
resources that are relevant to the quantity E;(psd)i (i.e., a frequency that
has not exceeded the
maximum aggregate radiated power) and/or another measure thereof. Thus, in
some
embodiments, the aggregate radiated power controller is configured to control
the plurality of
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radioterminals by reducing a vocoder rate of at least one of the
radioterminals, and/or
reducing a rate of information transmission of at least one of the
radioterminals, and/or
controlling at least one of the radioterminals to communicate using a
frequency that has not
exceeded the maximum aggregate radiated power, so as to limit an aggregate
radiated power
by the plurality of co-frequency radiotelephones to the maximum aggregate
radiated power.
Many different techniques also may be used to determine which radioterminal
and/or
which portion of the ancillary terrestrial network to control to reduce the
aggregate radiated
power, according to various embodiments of the present invention. Thus, in
some
embodiments, at least one radioterminal is selected and controlled as
described above, so as
to reduce the aggregate radiated power. In other embodiments, at least one
radioterminal that
is subject to a low, and in some embodiments a lowest, structural attenuation
margin and
which is, therefore, radiating at a relatively high level, may be controlled
according to any of
the embodiments described above.
Moreover, in other embodiments, a radioterminal may be selected based on the
frequency band and/or carrier frequency and/or air interface that it is using,
so that if a given
frequency band and/or carrier frequency and/or air interface exceeds a desired
maximum
aggregate radiated power, one or more radioterminals that is/are using that
frequency band
and/or carrier frequency and/or air interface may be controlled. Accordingly,
in some
embodiments, the aggregate radiated power controller is configured to control
a plurality of
radioterminals, by controlling at least one radioterminal that is
communicating with the ATN
over a frequency band and/or carrier frequency and/or air interface that has
exceeded a
maximum aggregated radiated power for that frequency band and/or carrier
frequency and/or
air interface, so as to limit the aggregate radiated power by the plurality of
radioterminals for
the frequency band and/or carrier frequency and/or air interface to a maximum
aggregate
radiated power for the frequency band and/or carrier frequency and/or air
interface. A priori
radiated power quotas for a given frequency band and/or carrier frequency
and/or air interface
thereby may be observed.
In yet other embodiments of the invention, the aggregate radiated power
controller is
configured to control the ancillary terrestrial network itself, i.e., the
terrestrial infrastructure,
to thereby reduce the radiated power by at least one radioterminal. In
particular, in some
embodiments, the aggregate radiated power controller is configured to
diversity combine
signals that are received from at least one radioterminal by at least two
ancillary terrestrial
components and/or by an ancillary terrestrial component and at least one
auxiliary antenna
system, to thereby reduce the radiated power by the at least one
radioterminal. The link
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margin and/or structural attenuation margin of ATN infrastructure components
may thereby
be increased.
More specifically, according to the Commission's analysis of the interference
potential to co-channel satellite systems by the ATN, the structural
attenuation margin
5 provided by an ATN infrastructure component on the return link(s) may be
increased or
maximized. Increasing or maximizing this parameter may have a direct impact on
the
frequency reuse and/or the number of co-frequency communications channels
allowed by the
ATN. For a given maximum EIRP of an ATN radioterminal, the margin available by
an
infrastructure component on a return link may be increased according to some
embodiments
10 of the invention, by increasing the number of receive antenna elements
on the ATN tower(s)
of the infrastructure component and/or by configuring at least some of the
receive antenna
elements to operate on multiple spatially-orthogonal dimensions. This approach
may yield
an infrastructure component able to provide (13 dB of structural attenuation
margin on forward
links and P dB of structural attenuation margin on return links, where > 0. In
the limit as
15 'T ¨> co, the radiotenninal EIRP approaches zero and so does the
interference potential to a
co-frequency satellite receiver. As such, the frequency reuse and/or the
number of co-
frequency communications channels allowed by the ATN may be increased.
Figure 19 is a schematic diagram of systems and methods according to
embodiments
of the present invention, wherein the aggregate radiated power controller of
Figure 18 is
20 configured to control an ancillary terrestrial network of Figure 19 to
diversity combine
signals that are received from at least one radioterminal by at least two
ancillary terrestrial
components and/or by an ancillary terrestrial component and at least one
auxiliary antenna
system, to thereby reduce the radiated power by the at least one
radioterminal. Moreover,
according to other embodiments of the present invention, embodiments of Figure
19 may be
25 used to increase link margin in a satellite radioterminal system that
includes an ATN,
independent of an aggregate radiated power controller.
Referring now to Figure 19, an ancillary terrestrial network 1850 includes a
plurality
of ancillary terrestrial components, shown in Figure 19 as first and second
ancillary terrestrial
components 1900a, 1900b, each of which communicates with at least one
radioterminal 1930
30 over an area that defines a respective cell 1920a, 1920b.
Still referring to Figure 19, a tower of the first ATC 1900a is configured
with one or
more transmit antennas and/or one or more receive antennas. As stated earlier,
at least some
elements comprising the transmitter and/or receiver antenna(s) of the
infrastructure
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41
component may be operative in more than one spatial dimension. Moreover, a
tower of the
second ATC 1900b may be configured with one or more transmit antennas and/or
one or
more receive antennas with at least some of the antenna elements thereof
operative in more
than one spatial dimension. The first ATC 1900a and the second ATC 1900b
comprising the
illustrative infrastructure component of Figure 19, may be adjacent ATCs. Each
ATC of an
ensemble of ATCs that may comprise an infrastructure component may have an
associated
cell 1920a, 1920b, that defines a cell edge inside of which the ATC is
configured to serve at
least one radioterminal 1930. A radioterminal that may be proximate to the
cell
boundaries/edges of at least two adjacent ATCs, as illustrated in Figure 19,
may be served
concurrently by at least two adjacent ATCs 1900a, 1900b.
Accordingly, an infrastructure component comprising at least two adjacent
ATCs, as
illustrated in Figure 19, may be configured to utilize one or more antenna
elements per ATC
to receive and process the transmissions of the radioterminal, which can
increase return link
robustness and/or available return link margin. For example, as shown in
Figure 19, a base
station processor 1930 of the second base station 1900b may be configured to
forward
transmissions that are received at the second base station 1900b from
radioterminal 1930 to a
diversity receiver 1902 at the first base station 1900a via a terrestrial
wired and/or wireless
link 1940. The diversity receiver also may be located, at least in part,
outside the first base
station 1900a. The diversity receiver 1902 may be used to combine the signals
that are
received at the second base station 1900b and the signals that are received at
the base station
1900a from radioterminal 1930, to thereby increase the return link robustness
and/or the
available return link margin. As such, the available return link margin and/or
structural
attenuation margin provided by the infrastructure component may be increased,
facilitating,
via closed-loop power control of the radioterminal by the infrastructure
component, a
reduction in output power by the radioterminal, thereby reducing the potential
of interference
to a co-frequency system such as a co-frequeney satellite system.
To increase or further increase the available return-link margin and/or return-
link
structural attenuation margin that may be provided by an infrastructure
component, according
to other embodiments of the present invention, at least one additional
auxiliary antenna
system 1910a-1910d may be disposed in the area/space between the cell edge and
the base
station tower of at least one ATC comprising the infrastructure component.
Figure 19
illustrates an infrastructure component configuration comprising two auxiliary
antenna
systems per ATC of the infrastructure component. However, greater or fewer
auxiliary
antenna systems 1910a-1910d may be used.
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Still referring to Figure 19, a diversity receiver 1902 may be configured to
accept and
process signals derived from the antenna systems of the first ATC 1900a,
auxiliary antenna
system 1910a, auxiliary antenna system 1910b, and from a base station
processor 1930
associated with the second ATC 1900b. The signals derived from the auxiliary
antenna
systems 1910a and/or 1910b and/or from the antenna system of ATC tower 1900a
may be
sent to the diversity receiver 1902 via physical connection(s) and/or
wirelessly. Similarly,
the signals derived from the auxiliary antenna systems 1910c and/or 1910d
and/or from the
antenna system of ATC tower 1900b may be sent to the base station processor
1930 via
physical connection(s) and/or wirelessly.
The base station processor 1930 may also comprise a diversity receiver. The
diversity
receiver 1902 and/or base station processor 1930 may be configured to combine
signals in
accordance with any conventional optimum and/or sub-optimum performance index
such as,
for example, maximal ratio combining. The auxiliary antenna system(s) 1910a-
1910d may
be configured to receive and/or transmit to/from radioterminals 1930.
Embodiments where
the auxiliary antenna system(s) is/are configured to transmit to
radioterminals may increase
the available forward-link margin and/or the forward-link structural
attenuation margin of the
infrastructure component.
Accordingly, a first ancillary terrestrial component for a satellite
radioterminal system
according to some embodiments of the present invention includes a subsystem,
such as a base
station tower 1900a that is configured to conununicate terrestrially with a
plurality a
radiotenninals 1930 over substantially the same frequency bands and/or air
interfaces as the
radioterminals communicate with a space-based component. A diversity receiver,
such as
diversity receiver 1902, is configured to diversity combine signals from a
radiotelephone
1930 that are received by the first ancillary terrestrial component 1900a
and/or by at least a
second ancillary terrestrial component 1900b, and/or by an auxiliary antenna
system 1910.
The auxiliary antenna system may be located in the first cell 1920a, such as
auxiliary antenna
systems 1910a, 1910b, or may be included outside the cell, such as auxiliary
antenna systems
1910c, 1910d. These embodiments may also be used to increase link margin,
independent of
control by an aggregate radiated power controller.
In conclusion, an ancillary terrestrial network can communicate terrestrially
with a
plurality of radioterminals over a plurality of frequency bands and/or a
plurality of air
interfaces, while the aggregate radiated power and/or power spectral density,
over any pre-
determined band of frequencies, may be limited to a predefined maximum.
CA 2 98 9660 2 01 7-12-1 9
WO 2004/100501 PCT/US2004/012541
43
In the drawings and specification, there have been disclosed embodiments of
the
invention and, although specific terms are employed, they are used in a
generic and
descriptive sense only and not for purposes of limitation, the scope of the
invention being set
forth in the following claims.
CA 2989660 2017-12-19
