Duplex satellite communication using a single frequency or pair

• US 6,768,900 B2
• Filed: 06/11/2002
• Issued: 07/27/2004
• Est. Priority Date: 11/29/1999
• Status: Expired due to Term

• Current Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Ottoson, Tony, Dent, Paul W.
• Primary Examiner(s): Gelin, Jean
• Application Number:
  US10/166,977
• Publication Number:
  US 20020168973A1
• Time in Patent Office: 777 Days
• Field of Search: 455/427, 455/428, 455/430, 455/12.1, 455/13.1, 455/16, 455/11.1, 455/17, 455/501, 455/63.1, 455/67.13, 455/114.1, 370/315, 370/529, 342/357.01, 342/352, 342/354
• US Class Current: 455/114.1
• 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 communication terminal in a mobile communication network, the communication terminal comprising:

a transmitter to transmit a first information-modulated signal on a first communications channel

a memory to store the first information-modulated signal;

a receiver to receive a combined signal on a second communications channel, the combined signal including the first information-modulated signal and a second information-modulated signal; and

a processor to process the combined signal received on the second communication channel, using the stored first information-modulated signal, to cancel interference from the combined signal attributable to the first information-modulated signal and to recover the second information-modulated signal.

2. The communication terminal of claim 1 wherein the communication terminal is a mobile terminal.

3. The communication terminal of claim 1 wherein the communication terminal is a network station.

4. The communication terminal of claim 1 wherein the first communications channel comprises a first frequency band and the second communications channel comprises a second frequency band.

5. The communication terminal of claim 1 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.

6. 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;

wherein the first communication terminal comprises;

memory to store the first information-modulated signal;

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

a processor to process the combined signal, using the stored first information-modulated signal, to cancel interference from the combined signal attributable to the first information-modulated signal and to recover the second information-modulated signal.

7. The communication system of claim 6 wherein the second communication terminal comprises a receiver to receive the combined signal on the second communication channel, memory to store the second information modulated signal, and a processor to process the combined signal, using the stored second information signal, to cancel interference from the combined signal attributable to the second information-modulated signal and to recover the first information-modulated signal.

8. The communication system of claim 6 wherein the first and second communication terminals are in the same cell.

9. The communication system of claim 6 wherein the first and second communication terminals are in different cells.

10. The communication system of claim 6 wherein the first communication terminal is a mobile terminal.

11. The communication system of claim 6 wherein the second communication terminal is a network station.

12. The communication system of claim 6 wherein the first communication terminal is a network station.

13. The communication system of claim 6 wherein the second communication terminal is a mobile terminal.

14. The communication system of claim 6 further comprising a third communication terminal comprising a receiver to receive the combined signal on the second communication channel and a processor.

15. The communication system of claim 14 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.

16. The communication system of claim 14 wherein the processor jointly demodulates the first and second information modulated signals in the combined signal.

17. The communication system of claim 6 wherein the first communications channel comprises a first frequency band and the second communications channel comprises a second frequency band.

18. The communication system of claim 6 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.