CDMA system architecture for satcom terminals
First Claim
1. A satellite communications system comprising:
- a hub station includingmeans for providing an outbound communications link for transmitting time division multiplexed signals from said hub to a plurality of remote terminals,means for implementing a frequency plan having fixed bandwidth steps, each of said bandwidth steps being partitioned into inbound and outbound carrier frequency subbands and having a fixed set of different PN codes which are re-used for each bandwidth step,means for broadcasting a list of available PN codes, available inbound carrier frequency subbands, and available outbound carrier frequency subbands, andmeans for receiving inbound code division multiple access (CDMA) signals using said PN codes; and
a plurality of remote terminals each includingmeans for providing an inbound communication link for transmitting CDMA signals from each of said remote terminals to said hub station, andmeans for randomly selecting an available inbound carrier frequency--PN code pair within a bandwidth step from said broadcasted list,means for receiving outbound time division multiplexed signals; and
a satellite, said satellite providing a relay for communications between said hub station and said remote terminals.
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Accused Products
Abstract
A satellite communication system including a portable satellite terminal is provided which utilizes C/Ku -band and spread spectrum technology to drastically reduce the antenna and terminal sizes. Both CDMA and time division multiplexing (TDM) are used to permit efficient all-digital voice, facsimile and data operations in either full mesh or star modes. A single Network Controller can handle both Star and Mesh mode traffic on the same or several transponders. Narrowband CDMA/frequency division multiple access is used for inbound transmission from the terminal while outbound transmissions from the hub utilize TDM/FDMA. Furthermore, the system is scalable in fixed bandwidth increments to support network size evolution. All signalling for call setup and takedown is done in-band on the same carrier that is used for the traffic, thereby eliminating the need for a separate signalling channel and frequency retuning. Only a small set of distinct PN code sequences, independent of the actual number of user terminals in the network, are required for the entire network.
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Citations
20 Claims
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1. A satellite communications system comprising:
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a hub station including means for providing an outbound communications link for transmitting time division multiplexed signals from said hub to a plurality of remote terminals, means for implementing a frequency plan having fixed bandwidth steps, each of said bandwidth steps being partitioned into inbound and outbound carrier frequency subbands and having a fixed set of different PN codes which are re-used for each bandwidth step, means for broadcasting a list of available PN codes, available inbound carrier frequency subbands, and available outbound carrier frequency subbands, and means for receiving inbound code division multiple access (CDMA) signals using said PN codes; and a plurality of remote terminals each including means for providing an inbound communication link for transmitting CDMA signals from each of said remote terminals to said hub station, and means for randomly selecting an available inbound carrier frequency--PN code pair within a bandwidth step from said broadcasted list, means for receiving outbound time division multiplexed signals; and a satellite, said satellite providing a relay for communications between said hub station and said remote terminals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of satellite communication between a hub station and a remote terminal comprising:
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creating a frequency plan having fixed bandwidth steps, each of said bandwidth steps being divided into inbound and outbound carrier frequency subbands, and having a fixed set of different PN codes which are re-used for each bandwidth step; broadcasting from said hub to said remote terminal a list of available PN codes corresponding to each available inbound carrier frequency subband within a particular bandwidth step which are not currently being used by any remote terminals; randomly selecting at said remote terminal an available inbound carrier frequency and PN code pair within a bandwidth step from transmitted said list to setup a communication link between said hub station and said remote terminal; removing at said hub station said selected inbound carrier frequency--PN code pair from said broadcasted list of available PN codes and carrier frequencies, transmitting inbound narrowband CDMA signals from said portable remote terminal to said hub station using said selected inbound carrier frequency--PN code pair; and transmitting outbound TDM signals from said hub station to said remote terminal using a selected outbound carrier frequency.
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18. A satellite communications system with full-duplex simultaneous transmission and reception comprising:
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a hub station including means for providing an outbound communications link for transmitting time division multiplexed signals from said hub to a plurality of remote terminals and means for creating a frequency plan based on fixed bandwidth steps each of said bandwidth steps being partitioned into inbound and outbound carrier frequency subbands and having a fixed set of PN codes which are the same for each bandwidth step; and a plurality of remote terminals each including means providing inbound communication link for transmitting CDMA signals from said remote terminals to said hub station or to other remote terminals, said hub station and said remote terminals having a network topology which may be interchangeably operated in both a star configuration and a mesh configuration without changes in signalling and occupied transponder bandwidth. - View Dependent Claims (20)
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19. A satellite communication system with full-duplex simultaneous transmission and reception comprising:
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a hub station including means for providing an outbound communications link for transmitting time division multiplexed signals from said hub to a plurality of remote terminals and means for transmitting a list of available PN codes corresponding to each available inbound carrier frequency subband within a bandwidth step; and a plurality of portable remote terminals each including means providing inbound communication link for transmitting CDMA signals from said remote terminals to said hub station or to other remote terminals and means for randomly selecting an available inbound carrier frequency--PN code pair within a bandwidth step from said transmitted list, said hub station and said remote terminals having a network topology which may be interchangeably operated in both a star configuration and a mesh configuration without changes in signaling and occupied transponder bandwidth.
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Specification