HIGH EFFICIENCY SUB-ORBITAL HIGH ALTITUDE TELECOMMUNICATIONS SYSTEM

SYSTEME DE TELECOMMUNICATIONS A HAUTE ALTITUDE, SUBORBITAL ET A GRANDE EFFICACITE

English Abstract

A wireless telecommunications system comprising a plurality of
telecommunications nodes (28) that include receivers and transmitters that are
located in a sub-orbital plane. The telecommunications signals are broadband
digital radio signals which are modulated by code division multiple access
spread spectrum technology. The receivers include a plurality of antennae (48)
that are operative to receive relatively weak telecommunications signals and
which use spatial processing to identify their source so that maximum
utilization of the spectrum is made available for use by the
telecommunications signals without interference.

French Abstract

Ce système de télécommunications sans fil comprend une pluralité de noeuds (28) de télécommunications qui comportent des récepteurs et des émetteurs placés dans un plan suborbital. Les signaux de télécommunications sont des signaux radio numériques à large bande qui sont modulés selon une technologie, à spectre dispersé, d'accès multiple par code de répartition. Les récepteurs comportent une pluralité d'antennes (48) qui fonctionnent pour recevoir des signaux de télécommunications relativement faibles et utilisent un traitement spatial pour identifier la source de ces signaux, de manière à ce que les signaux de télécommunications puissent disposer d'une utilisation maximum du spectre, sans qu'il y ait d'interférences.

Claims

Claims:
1. A wireless, telecommunications network system
comprising
a plurality of telecommunications nodes,
said nodes being located in a sub-orbital plane at
about 12 to 35 miles above the earth,
each of said nodes comprising means for sending and
receiving broadband, digital radio telecommunications signals
over a wireless telecommunications channel, said radio
telecommunications signals being modulated by code division
multiple access spread spectrum technology, and
said means for sending and receiving said radio
telecommunications signals further including a plurality of
antennae that are operative to receive relatively weak
telecommunications signals from a source,
means for decoding the telecommunications signals
received by each of said antennae so that said node can identify
said source, and
said antennae and said decoding means being operative
to increase the sensitivity of said node so that it can detect
and receive relatively weak telecommunications signals, so that
maximum utilization of said spectrum is made available for use
by said telecommunications signals without interference.
2. A system as defined in claim 1 wherein
said code division multiple access spread spectrum
technology is direct sequence.

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3. A system as defined in claim 1 wherein
said code division multiple access spread spectrum
technology is frequency hopping.
4. A system as defined in claim 1 wherein
said wireless telecommunications channel has a
frequency band width that is greater than about eight MHz.
5. A system as defined in claim 1 wherein
each of said nodes is stationary over its own point on
the earth.
6. A system as defined in claim 1 wherein
said means for sending and receiving broadband, digital
radio telecommunications signals over a wireless
telecommunications channel comprises
at least one transmitter and receiver, and
said transmitter and receiver carry a plurality of
duplex telecommunications channels.
7. A system as defined in claim 6 wherein
said transmitter is low powered and light weight.
8. A system as defined in claim 1 including
a terrestrial based telecommunications network, and
means for connecting said wireless, telecommunications
network system to said terrestrial based telecommunications
network.

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9. A system as defined in claim 8 wherein
said means for connecting said wireless,
telecommunications network system to said terrestrial based
telecommunications network includes switches.
10. A system as defined in claim 9 wherein
said switches are digital.
11. A system as defined in claim 9 wherein
said switches are analog.
12. A system as defined in claim 1 wherein
said nodes are supported by balloons.
13. A system as defined in claim 1 wherein
said wireless telecommunication frequencies are the
same as those allocated for terrestrial telecommunications.
14. A system as defined in claim 1 wherein
said means for sending and receiving broadband, digital
radio telecommunications signals over a wireless
telecommunications channel comprises
at least one transmitter and receiver and
said transmitter and receiver carry a plurality of
simplex telecommunications channels.
15. A system as defined in claim 14 wherein
said transmitter is low powered and light weight.

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16. A system as defined in claim 1 wherein
said means for sending and receiving broadband, digital
radio telecommunications signals over a wireless
telecommunications channel comprises
at least one transmitter and receiver, and
said transmitter and receiver carry a plurality of half
duplex telecommunications channels.
17. A system as defined in claim 16 wherein
said transmitter is low powered and light weight.
18. A system as defined in claim 1 wherein
said wireless telecommunication frequencies are the
same as those allocated for orbital telecommunications.
19. A system as defined in claim 1 wherein
said wireless telecommunication frequencies are
exclusively used by said telecommunications system.
20. A method for making wireless telecommunications
comprising the steps of
providing a plurality of telecommunications nodes, said
nodes defining a network,
locating said nodes in a sub-orbital plane at about 12
to 35 miles above the earth,
providing each of said nodes with means for sending and
receiving broadband, digital radio telecommunications signals
over a wireless telecommunications channel,

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providing each of said nodes with a plurality of
antennae that are operative to receive relatively weak digital,
radio telecommunications signals from a source,
modulating said telecommunications signals by code
division multiple access spread spectrum technology,
decoding said telecommunications signals received by
each of said antennae so that said node can identify said source,
and
said antennae and said decoding means being operative
to increase the sensitivity of said nodes so that they can detect
and receive said relatively weak telecommunications signals, so
that maximum utilization of said spectrum is made available for
use by said telecommunications signals without interference.
21. A method as defined in claim 20 wherein
said code division multiple access spread spectrum
technology is modified by direct sequence.
22. A method as defined in claim 20 wherein
said code division multiple access spread spectrum
technology is modified by frequency hopping.
23. A method as defined in claim 20 wherein
said wireless telecommunications channel has a
frequency band width that is greater than about eight MHz.

24. A method as defined in claim 20 wherein
each of said nodes is stationary over its own point on
the earth.
25. A method as defined in claim 20 wherein
said step of sending and receiving broadband, digital
radio telecommunications signals over a wireless
telecommunications channel comprises
the step of providing a plurality of transmitters and
receivers, and
each of said transmitters carrying a plurality of
duplex telecommunications channels.
26. A method as defined in claim 25 wherein
said transmitters are low powered and light weight.
27. A method as defined in claim 20 including the
steps of
providing a terrestrial based telecommunications
network, and
connecting said wireless, telecommunications network
system to said terrestrial based telecommunications network.
28. A method as defined in claim 27 including the step
of
providing switches for connecting said wireless,
telecommunications network system to said terrestrial based
telecommunications network.

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29. A method as defined in claim 28 wherein
said switches are digital.
30. A method as defined in claim 28 wherein
said switches are analog.
31. A method as defined in claim 20 including the step
of
supporting said nodes by balloons.
32. A method as defined in claim 20 wherein
said wireless telecommunication frequencies are the
same as those allocated for terrestrial telecommunications.
33. A method as defined in claim 20 wherein
said step of sending and receiving broadband, digital
radio telecommunications signals over a wireless
telecommunications channel comprises
the step of providing at least one transmitter and one
recelver, and
said transmitter and receiver carry a plurality of
simplex telecommunications channels.
34. A method as defined in claim 33 wherein
said transmitters are low powered and light weight.
35. A method as defined in claim 20 wherein
said step of sending and receiving broadband, digital

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telecommunications signals over a wireless telecommunications
channel comprises
the step of providing at least one transmitter and one
receiver, and
said transmitter and receiver carry a plurality of half
duplex telecommunications channels.
36. A method as defined in claim 35 wherein
said transmitters are low powered and light weight.
37. A method as defined in claim 20 wherein
said wireless telecommunication frequencies are the
same as those allocated for orbital telecommunications.
38. A method as defined in claim 20 wherein
said wireless telecommunication frequencies are
exclusively used by said telecommunications system.

Description

CA 022~4776 1998-11-12
WO 96/41429 PCT~US96/10230
HIGH EFFICIENCY SUB-ORBITAL HIGH
ALTITUDE TELECOMMUNICATIONS SYSTEM
Related Patent A~lications:
This patent application is a continuation-in-part of patent
application serial no. 08/100,037, filed July 30, 1993, entitled:
SUB-ORBITAL, HIGH ALTITUDE TELECOMMUNICATIONS SYSTEM.
Field Of The Invention:
This invention relates to a telecommunications system, and
more particularly to a telecommunications system that is
operative at the sub-orbital level and provides for increased
efficiency and increased utilization of available telecommunica-
tions channels.
Backqround of The Invention:
The growth of cellular telecommunications has placed
enormous strains on the ability of the industry to satisfactorily
handle the telecommunications traffic that has been generated.
Consequently, users of present analog cellular telecommuni-
cations systems find that they may have to wait for a telecommu-
nications channel to become available before they can place or
receive a call. Also, a call in progress may encounter interfer-
' ence in the form of noise or actually over-hearing another
conversation.

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Sometimes, a call may be cut off while in progress if one
of the parties moves to a cell that does not have an available
telecommunications channel. r
The problem is further aggravated by the fact that there are
only a limited number of frequencies allocated for cellular
telecommunications. Thus, the problem is expected to grow as the
demand for cellular telecommunications expands.
The industry has developed several improved analog and
digital technologies that have been successfully used to increase
the number of communications channels within the limited number
of available frequencies.
The most important of these technologies are time division
multiple access (TDMA) and code division multiple access (CDMA).
TDMA is the technology that has the widest use. It enables
a single telecommunications channel to be used for several calls.
Each call is allocated a particular discrete time interval in the
cycle of the telecommunications signals, thus, improving
efficiency.
CDMA uses a wide band of spectrum for telecommunications
signals to achieve efficiency. It differentiates between calls
by imprinting a distinctive "noise" spreading signal over each
telecommunications signal to differentiate it from other
telecommunications signals in the cell. The receiver with
computer assistance decodes the assigned "noise" signal to
identi~y the call and then despreads the teleco~mlln;cations
signal.

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'IFrequency hopping" is a form of CDMA that spreads a call
over a series of frequencies. It uses a code to identify the
sequence of frequencies that are being used.
Additionally, work has been done with respect to developing
systems which can identify weak signals emanating from a cell and
segregating those signals from other signals emanating from the
same cell so that when combined with a digital multiple access
technique such as CDMA, the number of available telecommunica-
tions channels is dramatically increased.
Attempts to increase the availability of telecommunications
channels have also included attempts to make the cells smaller
and to reduce the power requirements necessary for communicating
with a base station. This follows from the fact that a weak
signal has a reduced ability to propagate. Thus, since its
strength rapidly dissipates, the same frequency can be used in
a nearby non-contiguous cell.
However, to provide the requisite number of cells that would
be necessary to support a high volume of telecommunications,
there would have to be an enormous number of base stations. Some
experts estimate that at least 100,000 cells would be necessary
simply to cover major metropolitan areas in the United States.
Each cell would require its own stationary antenna tower.
In addition, an enormously complex computer system would be
required in order to deal with the hand-offs which would be
necessary as the cellular telephones moved from cell to cell and
to manage the reuse of the frequencies assigned to particular
calls.

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It is not certain that the problem can be solved with a
ground based system at a reasonable cost and in a reasonable
period. Thus, while the typical limitations associated with such
systems such as llne of sight, shadowing due to signal reflec-
tion, attenuation and horizon limitations, are eliminated by
reducing the size and increasing the number of cells, geograph-
ic, political, environmental and social factors may prohibit the
placing of antenna towers in certain locations thereby making it
not possible for cells of a suitable size to be achieved in those
locations.
A satellite system where each of the satellites functions
as a base station node and contributes to the creation of a
cellular network avoids these problems. However, in such a
system relatively powerful transmitters are required because the
satellites typically orbit at about 22,500 miles above the earth.
Further, unless they are geosynchronous, a means must be provided
for handing off signals from one satellite to another as they
pass a given point over the earth. Further, as with terrestrial
nodes, a hand off means is needed as a caller moves between
cells.
Additionally, satellite systems suffer from the enormous
cost in connection with launching, and the virtual impossibility
of repair.
Accordingly, with the foregoing in mind, the present
invention relates to a wireless telecommunications network system
comprising a plurality of telecommunications nodes that are
located in a sub-orbital plane. Each of the nodes comprises
means for sending and receiving broadband, digital radio
~rB

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telecommunications signals over a wireless telecommunications
channel. The telecommunications signals are modulated by code
division multiple access spread spectrum technology.
The means for sending and receiving wireless, digital
telecommunications signals include a plurality of antennae that
are operative to receive relatively weak telecommunications
signals from a source. Means are provided for decoding the
telecommunications signals received by each of said antennae so
that the node can identify the source, and the antenna and
decoding means are operative to increase the sensitivity of the
node so that it can detect and receive relatively weak telecommu-
nications signals, so that maximum utilization of the spectrum
is made available for use by the telecommunications signals
without interference.
Descri~tion of the Drawinq:
The invention can be further understood by referring to the
accompanying drawing of a presently preferred form thereof, and
wherein.
Figure 1 is a schematic drawing showing a telecommunications
system constructed in accordance with a presently preferred form
of the invention.
Figure 2 is a schematic drawing showing an aspect of the
detecting and decoding means.
~.

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Description of a Preferred Embodiment:
Referring now to Figure 1, a system 10 such as that
described in patent application serial no. 08/100,037 comprises
a ground based portion 12 and an air based portion 14. The air
based portion 14 may be located at an altitude of between about
12 to 35 miles above the earth.
The ground based portion 12 may comprise conventional
telephone network 16 with branches that are connected to ground
stations 18, 120 and 140 having suitable long distance transmit-
ting and receiving means such as antenna 20, 118 and 138. The
ground based portion 12 may also comprise mobile telephones of
well known types such as cellular telephones that may be carried
by individuals 22 or in vehicles 24. The antennae 20, 188 and
138 are operative to transmit and receive telecommunications
signals to and from a sub-orbital, high altitude relay station
28 which is located at an altitude of about 12 to 35 miles above
the earth. This altitude is selected because it is well above
weather activity so that the relay station will not be subjected
to the strains that the weather might cause.
Preferably, there are a plurality of relay stations 28; each
comprising a balloon 32 that is retained aloft and on station
over a particular place over the earth by using a guidance module
56 which is connected by a guidance antenna 58 to ground lin~
antennae 36 as described in parent patent application serial no.
08/100,037, filed July 30, 1993.
As is well known, each relay station 28 contains means for
receiving a telephone telecommunications signal from one of the
ground stations 20, 120 and 140 individuals 22 and 122 or

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vehicles 24 and 124 and then transmitting it to another ground
station 120 and 140, individual 122 or vehicle 124 either
directly or by way of another relay station. The communications
channel so established could be simplex, duplex or half duplex.
Once the signal returns to the ground based portion 12 of the
system 10, the telecommunications call is completed in a conven-
tional manner as by being connected to the ground-based, wired
telephone system through suitable switches 34, 134 and 144. The
switches may be of any type suitable for telecommunications
signals including digital and analog.
As is well known, each of the relay stations 28 defines a
node in the telecommunications system with each node defining a
"cell." Preferably, each of the nodes comprises means for
sending and receiving broadband, digital radio telecommunications
signals over a wireless telecommunications channel. Preferably,
the telecommunications channel has a frequency band width that
is greater than about 8 MHz. The telecommunications signals are
preferably modulated by code division multiple access spread
spectrum technology.
To maximize the utilization of the available frequencies
beyond that which is currently available with CDMA, the cells
should be relatively small and the signal power required for
telecommunications signals very low. This will enhance the
reusability of frequencies and reduce interference. However,
~ reduced signal strength makes it more difficult for the base
stations to trac~ the movement of particular cellular phones.
A detection system comprising a suitable array of antennae
48 and decoders 44 on each of the relay stations is provided.

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The detection system is of a type similar to the spatial
processing system that is described in FORBES ASAP; June 5, 1995,
at pages 125 - 141. The system processes the signal received by '
each of the antennas in the array. The decoded signals identify
the transmitter and its location in the cell. Thus, even though
a very weak signal, which ordinarily might be lost, is received
by the detection system it can still be recognized and processed
to complete a telecommunications channel.
The advantages of the combination of spread spectrum CDMA
and the detection system comprising the antenna array described
above are enhanced when combined and placed in the sub-orbital
plane since all of the disadvantages of both terrestrial and
satellite systems are avoided while their advantages, such as
vertical signal propagation are maintained thereby increasing the
utilization of the telecommunications spectrum. Further, power
requirements can be lowered and the weight of the transmitters
at the nodes can be reduced correspondingly. In addition because
of the modulation technique the number of transmitters can be
reduced.
Thus, a large number of telecommunications ch~nnels can be
established in a cell defined by a particular node without the
attendant problems of interference arising from crosstalk,
reflection, frequency reuse and the like.
Additionally, the relatively high power requirements that
such a system would require if it were associated with a
satellite based telecommunications system are avoided.
It is contemplated that the system which has been described
will be using code division multiple access spread spectrum
,

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technology; encompassing direct sequence and/or frequency hopping
techniques.
Still further, while the frequency allocations for the
telecommunications system have not been identified with particu-
larity, it should be understood that they could be the same as
those allocated for terrestrial telecommunications, or those
allocated for satellite telecommunications. Similarly, it is
within the scope of the invention for the frequencies to be those
which are exclusively for use by the telecommunications system.
While the invention has been described with respect to
certain forms and embodiments, it is apparent that other forms
will be obvious to those skilled in the art in light of the
foregoing description. Thus, the scope of the invention should
not be limited by the description, but rather, only by the scope
of the claims appended.

Representative Drawing