Multiple access spread spectrum switching methodology
A low-cost, low-power, low-complexity, small, high-reliability, robust, seamless satellite communication network is described. The network performs encoding of a user signal at the customer premises to enable routing of the user signal to an appropriate destination beam at the satellite requiring low power user signal processing. Routing information is embedded at the periphery of the network CPE's rather than at the satellite. Embedding the routing information in this way greatly reduces on-board switching complexity and increases signal to interference ratio for the user.
1. On-board satellite equipment for combining received digital user signals from a plurality of origination beams to produce a plurality of destination beams, the satellite equipment comprising:
a first digital decoder comprising a processor and computer readable media containing computer readable instructions that, when executed by the processor, cause the first digital decoder to apply on a received digital signal a first code unique to a particular received origination beam to extract digital user signals received in the particular origination beam to create a first intermediate digital signal;
a digital summing circuit comprising a processor and computer readable media containing computer readable instructions that, when executed by the processor, cause the digital summing circuit to combine the first intermediate digital signal with isolated user signals from other origination beams to produce a summation signal;
a second digital decoder comprising a processor and computer readable media containing computer readable instructions that, when executed by the processor, cause the second digital decoder to apply on the summation signal a second code to extract digital user signals of the summation signal that are destined for a particular destination beam, to produce other isolated user signals from the plurality of origination beams and destined for the particular destination beam; and
a digital encoder comprising a processor and computer readable media containing computer readable instructions that, when executed by the processor, cause the digital encoder to apply on the other isolated user signals a third code for further isolating the particular destination beam.
2. The on-board satellite equipment of claim 1 , wherein the first and second digital decoders are code division multiple access decoders.
3. The on-board satellite equipment of claim 1 , wherein the first code unique to the received beam is a chipping sequence.
4. The on-board satellite equipment of claim 1 , wherein the digital encoder improves a signal-to-interference ratio of the particular destination beam.
5. The on-board satellite equipment of claim 1 , further comprising:
a radio processing device for converting a received signal to a received intermediate user signal, the radio processing device comprising at least one of a low-noise amplifier, a filter and a down-converter.
6. The on-board satellite equipment of claim 5 , further comprising a demodulator for demodulating the received intermediate user signal to produce the received digital signal.
7. The on-board satellite equipment of claim 6 , further comprising a timing circuit for extracting timing information from the demodulator and for providing the timing information to at least one of: the first and second digital decoders, the digital summing circuit, and the digital encoder.
8. The on-board satellite equipment of claim 1 , wherein the first digital decoder is one of a plurality of digital decoders applying respective codes on the received digital signal, each respective code being unique to a respective particular received origination beam, each respective digital decoder being for extracting digital user signals received in the respective particular origination beam, to create respective first intermediate digital signals.
9. The on-board satellite equipment of claim 1 , wherein the plurality of origination beams contains user signals encoded using the first code and the second code.
10. The on-board satellite equipment of claim 1 , wherein the first code is an orthogonal code associated with the origination beam.
11. A method for combining received digital user signals from a plurality of origination beams to produce a plurality of destination beams, comprising:
in a first digital decoder, applying on a received digital signal a first code unique to a particular received origination beam to extract digital user signals received in the particular origination beam to create a first intermediate digital signal;
in a digital summing circuit, combining the first intermediate digital signal with isolated user signals from other origination beams to produce a summation signal;
in a second digital decoder, applying on the summation signal a second code to extract digital user signals of the summation signal that are destined for a particular destination beam, to produce other isolated user signals from the plurality of origination beams and destined for the particular destination beam; and
in a digital encoder, applying on the other isolated user signals a third code for further isolating the particular destination beam.
12. The method of claim 11 , wherein the first and second codes are applied by code division multiple access decoders.
13. The method of claim 11 , wherein the first code unique to the received beam is a chipping sequence.
14. The method of claim 11 , wherein applying the third code improves a signal-to-interference ratio of the particular destination beam.
15. The method of claim 11 , further comprising:
converting a received signal to a received intermediate user signal, by processing the received signal with at least one of a low-noise amplifier, a filter and a down-converter.
16. The method of claim 15 , further comprising:
demodulating the received intermediate user signal to produce the received digital signal.
17. The method of claim 16 , further comprising:
extracting timing information from the received intermediate user signal; and
using the timing information in at least one of: applying the first, second and third codes and combining the isolated user signals.
18. The method of claim 11 , further comprising:
separately applying a plurality of respective codes on the received digital signal, each respective code being unique to a respective particular received origination beam; each respective code extracting digital user signals received in the respective particular origination beam, to create respective first intermediate digital signals.
19. The method of claim 11 , wherein the plurality of origination beams contains user signals encoded using the first code and the second code.
20. The method of claim 11 , wherein the first code is an orthogonal code associated with the origination beam.