Duplex satellite communication using a single frequency or pair

• US 20020168973A1
• Filed: 06/11/2002
• Published: 11/14/2002
• Est. Priority Date: 11/29/1999
• Status: Active Grant

• Current Assignee: Paul W. Dent, Tony Ottoson
• Original Assignee: Paul W. Dent, Tony Ottoson
• Inventors: Ottoson, Tony, Dent, Paul W.
• Granted Patent: US 6,768,900 B2
• Time in Patent Office: Days
• US Class Current: 455/427
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system
• CPC Class Codes: H04B 7/216 Code division or spread-spectrum multiple access [CDMA, SSMA]
• CPC Class Codes: H04L 5/06 the signals being represented by different frequencies combined with time-division multiplexing H04L5/26

Abstract

An improved satellite communications system allows for greater spectral efficiency by requiring just two frequencies for wireless communications between a first ground-based station and a second ground-based station via a satellite. Both the first station and the second station use the first frequency to transmit signals to the satellite; the satellite transponds the signals it receives on the first frequency to the second frequency and transmits the signals to the first and second stations on the second frequency. Use of two frequencies in such a manner results in some own-signal interference. The first station preferably stores its outgoing signals in memory and then subtracts out these stored signals to eliminate the its own-signal interference. The second station may likewise store and subtract out its transmissions, but this is not required. The present invention also contemplates that each satellite beam cell will have its own network station, thereby allowing for simpler antenna configurations to be used.

Claims

1. A satellite communications system, comprising:

at least one satellite having a plurality of antenna beams, each of the antenna beams corresponding to a different terrestrial geographic area;

at least one terrestrial network station disposed within each of the terrestrial geographic areas, the network stations in communication with the satellite for conveying user-selected information there between; and

at least one mobile station within one of the geographic areas, the mobile station communicating the user-selected data to the network station within the geographic area via the satellite.

2. The satellite communications system of claim 1 wherein the mobile station and the network station within the geographic area both transmit to the satellite on a first communications channel and receive from the satellite on a second communications channel, and wherein the satellite simultaneously receives signals from the mobile station and the network station on the first communications channel, and wherein the satellite transponds the received signals to the second communications channel.

3. The satellite communications system of claim 2 wherein the mobile station includes memory for temporarily buffering data transmitted to the satellite and wherein the mobile station decodes information signals received from the network station via the satellite on the second communication channel based on the temporarily buffered data.

4. The satellite communications system of claim 2 wherein the temporarily buffered data is discarded no later than immediately after the information signals received from the network station via the satellite on the second communications channel are decoded by the mobile station.

5. The satellite communications system of claim 2 wherein the first communications channel comprises a first frequency band and the second communications channel comprises a second frequency band.

6. The satellite communications system of claim 2 wherein the first communications channel comprises a first time slot in a first frequency band and the second communications channel comprises a second time slot in the first frequency band.

7. A communication terminal in a mobile communication network, the communication terminal comprising:

a transmitter to transmit a first information-modulated signal on a first communication channel to a relay station that combines the first information modulated signal with a second information modulated signal to form a combined signal and transmits the combined signal on a second communication channel;

a receiver to receive the combined signal on the second communication channel; and

a processor to process the combined signal from the relay station received on the second communication channel to remove the first information signal from the combined signal and to decode the second information signal.

8. The communication terminal of claim 7 wherein the communication terminal further comprises memory to store the transmitted first information modulated signal.

9. The communication terminal of claim 7 wherein the communication terminal is a mobile terminal.

10. The communication terminal of claim 7 wherein the communication terminal is a network station.

11. The communication terminal of claim 7 wherein the first communications channel comprises a first frequency band and the second communications channel comprises a second frequency band.

12. The communication terminal of claim 7 wherein the first communications channel comprises a first time slot in a first frequency band and the second communications channel comprises a second time slot in the first frequency band.

14. The relay station of claim 13 wherein the receiver comprises an antenna for receiving the combined signal from a first communication terminal on the first communication channel and further for transmitting the converted combined signal to a second communication terminal on the second communication channel.

15. The relay station of claim 14 wherein the antenna comprises a multi-beam antenna.

16. The relay station of claim 15 wherein each beam of the multi-beam antenna covers a different cell.

17. The relay station of claim 14 wherein the first communication terminal comprises a network station.

18. The relay station of claim 14 wherein the first communication terminal comprises a mobile terminal.

19. The relay station of claim 14 wherein the second communication terminal comprises a network station.

20. The relay station of claim 14 wherein the second communication terminal comprises a mobile terminal.

21. The relay station of claim 13 wherein the relay station is a satellite.

22. The relay station of claim 13 wherein the first communications channel comprises a first frequency band and the second communications channel comprises a second frequency band.

23. The relay station of claim 13 wherein the first communications channel comprises a first time slot in a first frequency band and the second communications channel comprises a second time slot in the first frequency band.

25. The communication system of claim 24 wherein the first communication terminal comprises a receiver to receive the combined signal on the second communication channel, memory to store the transmitted first information modulated signal, and a processor to remove the first information modulated signal stored in the memory from the combined signal and decode the second information signal.

26. The communication system of claim 24 wherein the second communication terminal comprises a receiver to receive the combined signal on the second communication channel, memory to store the transmitted first information modulated signal, and a processor to remove the second information signal stored in the memory from the combined signal and decode the first information signal.

27. The communication system of claim 24 wherein the first and second communication terminals are in the same cell.

28. The communication system of claim 24 wherein the first and second communication terminals are in different cells.

29. The communication system of claim 24 wherein the first communication terminal is a mobile terminal.

30. The communication system of claim 24 wherein the second communication terminal is a network station.

31. The communication system of claim 24 wherein the first communication terminal is a network station.

32. The communication system of claim 24 wherein the second communication terminal is a mobile terminal.

33. The communication system of claim 24 further comprising a third communication terminal comprising a receiver to receive the combined signal on the second communication channel and a processor.

34. The communication system of claim 33 wherein the processor decodes the stronger of the first and second information modulated signals, subtracts it from the combined signal, and decodes the remaining signal.

35. The communication system of claim 33 wherein the processor jointly demodulates the first and second information modulated signals in the combined signal.

36. The communication system of claim 24 wherein the first communications channel comprises a first frequency band and the second communications channel comprises a second frequency band.

37. The communication system of claim 24 wherein the first communications channel comprises a first time slot in a first frequency band and the second communications channel comprises a second time slot in the first frequency band.

13. A relay station for a mobile communication network, the relay station comprising:

a receiver to receive a combined signal on a first communication channel, the combined signal comprising first and second superimposed information-modulated signals; and

a transponder to frequency convert the combined signal received on the first communication channel and to transmit the combined signal on a second communication channel.

24. A communication system comprising:

a first communication terminal transmitting a first information-modulated signal on a first communication channel;

a second communication terminal transmitting a second information-modulated signal on the first communication channel; and

a relay station having a receiver to receive a combined signal comprising the first and second information modulated signals superimposed and a transponder to retransmit the combined signal on a second information channel.