Note: Descriptions are shown in the official language in which they were submitted.
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Increased Feeder Link Capacity for Geosynchronous Satellite Communications
FIELD
100011 A feeder link capacity of a High Throughput Satellite (HTS) cannot be
exhausted with a conventional number of gateways. A single satellite may be
used to
minimally increase a cost of the satellite system by the use of higher
frequency feeder link
spectrum to communicate with the satellite. For a given geographic area, a
decreased number
of gateways with acceptable interference levels among them can be used to
exhaust the feeder
link capacity of a HTS
BACKGROUND
100021 Each generation of Geosynchronous High Thruput Satellites (HTSs) has
realized a significant increase in capacity/beam count. Satellite feeder link
capacity has more
than tripled between generations. Using Ka-band alone to exhaust the satellite
capacity
would require more than 60 gateway sites. Such a large number of gateways for
a satellite is
expensive in time, labor and management. Higher frequency feeder link spectrum
has not
been used to communicate with the Geosynchronous satellite. The V/Q-band
spectrum has
not been used for communications between a Geosynchronous satellite and a
satellite
gateway.
SUMMARY
100031 This Summary is provided to introduce a selection of concepts in a
simplified
form that is further described below in the Detailed Description. This Summary
is not
intended to identify key features or essential features of the claimed subject
matter, nor is it
intended to be used to limit the scope of the claimed subject matter.
100041 The present teachings disclose using the V/Q band (50/40 GHz), singly
or in
combination, with the Ka-band to keep a gateway count for HIS to be less than
20, for
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example, 18. The multibeam satellite system communicates with multiple
gateways in the
same time-frequency to provide spatially multiplexed signals for uplink and
downlink
channels on a feeder link side.
100051 A system to reduce a count of satellite gateways is disclosed. The
system
includes: a feeder link capacity of a satellite; a spectrum ranging from 26.5
GHz to 75 GHz; a
gateway feeder link capacity that is an aggregate of capacities of channels
defined in the
spectrum; and RF gateways communicating with the satellite via the channels,
wherein the
count of the satellite gateways is less than or equal to a rounded-up integer
of the feeder link
capacity divided by the gateway feeder link capacity, and the satellite is a
geosynchronous
orbit satellite.
100061 The system where the feeder link capacity of the satellite is greater
than 80
GHZ, and the gateway feeder link capacity is greater than or equal to 10 GHz.
100071 The system where the feeder link capacity of the satellite is greater
than 80
GHZ, and the count of the satellite gateways is less than 20.
100081 The system where the feeder link capacity of the satellite is greater
than 150
GHZ, and the gateway feeder link capacity is greater than or equal to 11 GHz.
100091 The system where the spectrum ranges from 40 GHz to 75 GHz.
100101 The system where the spectrum ranges from 26.5 GHz to 52 GHz.
100111 The system where the spectrum is non-contiguous.
100121 The system where the spectrum ranges from 26.5 GHz to 29.5 GHZ and 47
GHz to 52 GHz.
100131 The system where one of the channels is defined by a non-contiguous
frequency band.
100141 The system where some of the capacities of the channels are different
than
capacities of other channels.
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100151 The system including a forward error encoder to encode a respective
data
stream assigned to one of the channels.
100161 The system including a pre-transmission interference processor of a Tx
signal
on one of the channels, wherein the spectrum is divided into portions and a
compensation by
the pre-transmission interference processor is based on portions of the
spectrum being
transmitted by the Tx signal.
100171 The system where the feeder link capacity of the satellite is greater
than 150
GHZ, the gateway feeder link capacity is greater than or equal to 11 GHz, the
count of the
satellite gateways is less than 20, and the spectrum ranges from 26.5 GHz to
29.5 GHZ and
47 GHz to 52 GHz.
100181 The system including a post-transmission interference processor to
recover an
Rx signal on one of the channels.
100191 Additional features will be set forth in the description that follows,
and in part
will be apparent from the description, or may be learned by practice of what
is described.
DRAWINGS
100201 In order to describe the manner in which the above-recited and other
advantages and features may be obtained, a more particular description is
provided below and
will be rendered by reference to specific embodiments thereof which are
illustrated in the
appended drawings. Understanding that these drawings depict only typical
embodiments and
are not, therefore, to be limiting of its scope, implementations will be
described and
explained with additional specificity and detail with the accompanying
drawings.
100211 FIG. 1 illustrates a satellite feeder link system in one embodiment.
100221 FIG. 2 lists an exemplary spectrum used by an RF gateway of according
to
various embodiments.
100231 Throughout the drawings and the detailed description, unless otherwise
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described, the same drawing reference numerals will be understood to refer to
the same
elements, features, and structures. The relative size and depiction of these
elements may be
exaggerated for clarity, illustration, and convenience.
DETAILED DESCRIPTION
100241 Embodiments are discussed in detail below. While specific
implementations
are discussed, this is done for illustration purposes only. A person skilled
in the relevant art
will recognize that other components and configurations may be used without
parting from
the spirit and scope of the subject matter of this disclosure.
100251 The terminology used herein is for describing embodiments only and is
not
intended to be limiting of the present disclosure. As used herein, the
singular forms "a," "an"
and "the" are intended to include the plural forms as well, unless the context
clearly indicates
otherwise. Furthermore, the use of the terms "a," "an," etc. does not denote a
limitation of
quantity but rather denotes the presence of at least one of the referenced
items. The use of
the terms "first," "second," and the like does not imply any order, but they
are included to
either identify individual elements or to distinguish one element from
another. It will be
further understood that the terms "comprises" and/or "comprising", or
"includes" and/or
"including" when used in this specification, specify the presence of stated
features, regions,
integers, steps, operations, elements, and/or components, but do not preclude
the presence or
addition of one or more other features, regions, integers, steps, operations,
elements,
components, and/or groups thereof. Although some features may be described
with respect
to individual exemplary embodiments, aspects need not be limited thereto such
that features
from one or more exemplary embodiments may be combinable with other features
from one
or more exemplary embodiments.
100261 The present teachings disclose a multibeam satellite system that can
achieve
orthogonality between spatially multiplexed signals when operating in line-of-
sight (LOS)
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channels, using satellite links utilizing a large frequency spectrum. By
utilizing a larger
frequency spectrum, a capacity/bandwidth of satellite links from a gateway to
a satellite and
satellite to the gateway can be increased.
100271 The satellite link may operate in a Ka band, Q band, or V band. In an
exemplary embodiment, the V and Ka bands may be used on the gateway to
satellite feeder
link and the Q-band may be used on the satellite to gateway feeder link. The
Ka band may be
used for feeder links in either direction. The Ka band is a portion of the
electromagnetic
spectrum defined as frequencies in the range of 26.5-40 gigahertz (GHz). The Q
band is a
range of frequencies included in the microwave region of the electromagnetic
spectrum in a
range of 33 to 50 GHz. The V band is a band of frequencies in the microwave
portion of the
electromagnetic spectrum ranging from 40 to 75 GHz. The frequency spectrum
used for the
satellite links may be non-contiguous. In some embodiments, a downlink
frequency
spectrum (satellite to gateway) may be disposed between portions of an uplink
frequency
spectrum (gateway to satellite).
100281 The present teachings are applicable to a Geosynchronous Earth Orbit
(GEO)
satellite system, as long as LOS channels, in particular, dominant LOS
channels are used. In
a dominant LOS channel, a free space signal from the transmitter to the
receiver is stronger
than a scattered space signal from the transmitter to the receiver. In some
embodiments,
linear pre-processing at the gateways mitigates interference and spatially
separates the
multiplexed signals without requiring matrix processing onboard the satellite
for an uplink
(gateway to satellite). In some embodiments, for the downlink, linear post-
processing at the
gateways may mitigate interference and spatially separate the multiplexed
signals without
requiring matrix processing onboard the satellite The gateway-based linear pre
and post
processing of a signal in LOS may be used with satellite bent-pipe
architectures.
100291 FIG. 1 illustrates a satellite feeder link system in one embodiment.
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100301 FIG. 1 illustrates a system 100 (or satellite feeder link system 100)
including a
satellite link 102 (wireless), an RFT 104 (Radio Frequency Terminal), an RF
gateway 106, an
lnterfacility Link (IFL 110), a fiber link 112 and a data center 108. The data
center may be
connected to the Internet 114. The RFT 104 may communicate with a satellite
116 via the
satellite link 102. When the satellite link 102 communicates from the RFT 104
to the satellite
116, it is referred to as an uplink. When the satellite link 102 communicates
from the satellite
116 to the RFT 104, it is referred to as a downlink.
100311 The RFT 104 includes an antenna system and associated RF electronics
(typically housed in a hub located near a reflector). This includes
electronics to provide a Tx
path (frequency conversion from an Intermediate Frequency (IF) to RF and
amplification)
and Rx path (Low noise RF amplification followed by frequency conversion from
RF to IF)
as well as other electronics. The RFT 104 includes a reflector, which may
collect radio waves
from the satellite and convert the collected radio waves to a signal for the
Rx path sent
through the IFL 110 to the RF gateway 106. This conversion of RF to a lower
block of IF-,
allows the signal to be carried, e.g., via a wired connection such as the IFL
110, to the RF
gateway 106. Typically, the RF gateway includes baseband modems, data
processing, and a
networking interface to data center 108 via the fiber link 112. In some
embodiments, the
RFT 104 and the RF gateway 106 may be collocated (for example, within an
antenna
structure), while the data center 108 may be remote, for example, 10, 20, 100
or the like
kilometers away.
100321 The RFT 104 typically includes a sender antenna configured to send
radio
frequency waves to a satellite The RFT 104 is electrically wired to the RF
gateway 106 to
receive an outgoing RF signal via the IFL 110 and to send the RF signal via
the satellite link
102 to the satellite 116. In the present context, a satellite link is a
wireless communication
between the RF gateway 106, the RFT 104 and satellite 116. Satellite link 102
is typically
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established upon configuring a modem modulator, demodulator, encoder, and/or
decoder.
100331 The RF gateway 106 may provide pre-interference interference processing
for
a Tx signal prior to transmitting. The RF gateway 106 may provide post-
interference
interference processing for a Rx signal upon receipt. The pre and post
interference
processing may be
100341 The data center 108 may be connected to the RF gateway 106 via a fiber
link.
The data center 108 may provide access to the Internet, bandwidth allocation,
network
address translation, system management, diversity management and the like for
terminals
(not shown) connected via a wireless link (not shown) from the satellite to
the terminals, and
the Internet 114 The data center 108 may be connected to multiple Points of
Presence
(POPs) to access the Internet 114. The data center 108 may service multiple RF
gateways.
The data center 108 may serve all or some of the RF gateways of a system 100.
The RFGW
106 typically resides in a collocated data center 108. As such, the fiber link
112 would be a
cross-connect or short run connection within the data center 108. In some
embodiments, the
RF gateway 106 may not be collocated with the RF gateway 106 and the fiber
link 112 can be
significant distance.
100351 Significant gains are made when compared with systems that do not use
the
Ka, Q and V bands for uplinks or downlinks between a gateway and a satellite.
100361 FIG. 2 lists an exemplary spectrum used by an RF gateway of according
to
various embodiments. The spectrum uses portions of the Ka, Q and V bands. The
spectrum
is non-contiguous. Capacity provided by the RF gateway is doubled by using
right-hand and
left-hand polarizations concurrently. The Rx channels are disposed between the
Tx channels.
100371 In this example, RF gateway's Tx feeder link capacity is about 12 GI-
Iz, and
the RF gateway's Rx feeder link capacity is about 4 GHz. The gateway feeder
link capacity
is sum of the two, namely, 16 GHz. At least the RF gateway's Tx feeder link
capacity is
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about 3 times greater than typical RF gateway installations. As such, the
number of RF
gateways needed to exhaust a feeder link capacity of a satellite is reduced by
at least a factor
of three (3).
100381 In FIG. 2, 1 GHz of the RF gateway's Tx feeder link capacity may be
used for
system signaling. In such a configuration, the RF gateway's Tx feeder link
capacity is about
11 GHz, and the gateway feeder capacity is about 15 GHz. In some embodiments,
the
gateway feeder link capacity may be greater than or equal to 8 GHz, 10 GHz, 12
GHz, 15
GHz, 25 GHz or the like.
100391 Although the subject matter has been described in language specific to
structural features and/or methodological acts, it is to be understood that
the subject matter in
the appended claims is not necessarily limited to the specific features or
acts described above.
Rather, the specific features and acts described above are disclosed as
example forms of
implementing the claims. Other configurations of the described embodiments are
part of the
scope of this disclosure. Further, implementations consistent with the subject
matter of this
disclosure may have more or fewer acts than as described or may implement acts
in a
different order than as shown. Accordingly, the appended claims and their
legal equivalents
should only define the invention, rather than any specific examples given.
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