Adaptive coding scheme for a processing communications satellite

• US 6,625,776 B1
• Filed: 09/30/1998
• Issued: 09/23/2003
• Est. Priority Date: 09/30/1998
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Corporation
• Inventors: Perahia, Eldad, Wilcoxson, Donald C., Wright, David A., Linsky, Stuart T.
• Primary Examiner(s): Decady, Albert
• Assistant Examiner(s): CHAUDRY, MUJTABA M
• Application Number:
  US09/163,775
• Time in Patent Office: 1,819 Days
• Field of Search: 714/774, 714/704, 714/752, 714/812, 714/708, 714/810, 375/224, 375/130, 369/13.02
• US Class Current: 714/774
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0015 characterised by the adaptation strategy
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/0065 Serial concatenated codes

Abstract

The present invention provides a comprehensive method for controlling, independently, transmit power and coding levels for data transmitted in uplinks and downlinks. One preferred embodiment of the present invention provides a method for adaptive coding of data in a downlink. A data error rate associated with downlink data (e.g., a character error rate provided by a Reed Solomon decoder) is determined. The method, based upon pre-established error rate thresholds, controls the level of coding (e.g., heavy or light) on data in the downlink to achieve a desired data error rate. Heavy coded data is typically associated with a code rate half that of light coded data, and changes between heavy and light coding may be selected using a destination address applied at an originating terminal and interpreted at the satellite.

Claims

1. In a satellite communications system including terminals which send and receive data through a satellite, a method for adaptive error control coding of data in a downlink the method comprising the steps of:

receiving at a destination terminal a downlink including light coded data transmitted by a satellite;

determining a first data error rate associated with said light coded data;

when said first data error rate exceeds a first threshold, commanding said originating terminal to subsequently select transmission of heavy coded data having a code rate less than said light coded data in said downlink to said destination terminal;

when said first data error rate falls below a second threshold, commanding said originating terminal to subsequently select transmission of light coded data in said downlink to said destination terminal;

establishing an enter-suspension threshold;

determining a second data error rate associated with said heavy coded data; and

commanding said first originating terminal to suspend transmission when said second data error rate exceeds said enter-suspension threshold,

wherein said first threshold is different from said second threshold and said enter-suspension threshold.

2. The method of claim 1, further comprising the steps of:

establishing an exit-suspension threshold separated from said enter suspension threshold by a suspension hysteresis interval;

commanding said originating terminal to resume transmission when said second data error rate falls below said exit-suspension threshold.

3. The method of claim 2, wherein said step of commanding to resume transmission further comprises commanding said originating terminal to select transmission of heavy coded data in said downlink to said destination terminal.

4. The method of claim 1, wherein said step of commanding to suspend transmission further comprises commanding a Network Operation Control (NOC) to suspend transmission to said destination terminal.

5. The method of claim 2, wherein said step of commanding to resume transmission comprises commanding originating terminal to resume transmissions.

6. The method of claim 2, wherein said step of commanding to resume transmission comprises commanding a Network Operation Control (NOC) to resume transmission to said destination terminal.

11. The method of claim 1, wherein said step of determining a second data error rate comprises determining a second data error rate associated with data in said downlink originating at a second originating terminal.

13. The method of claim 2, wherein said step of commanding to subsequently select transmission of heavy coded data comprises the step of selecting transmission of data in said downlink of heavy coded data having a code rate half that of light coded data.

7. In a satellite communications system including terminals which send and receive data through a satellite, a method for adaptive error control coding of data in a downlink, the method comprising the steps of:

receiving at a destination terminal a downlink including light coded data transmitted by a satellite;

determining a first data error rate associated with said light coded data;

when said first data error rate exceeds a first threshold, commanding said originating terminal to set an address bit to a heavy coding value having a code rate less than said light coded data in said downlink to said destination terminal; and

when said first data error rate falls below a second threshold, commanding said originating terminal to subsequently select transmission of light coded data in said downlink to said destination terminal,

wherein said first threshold is different from said second threshold.

8. The method of claim 7, further comprising the step of applying, at a satellite, an inner code selected by said address bit to form said heavy coded data in said downlink.

12. The method of claim 8, wherein said step of applying an inner code comprises applying a heavy inner code having a code rate half that of a light inner code.

9. In a satellite communications system including terminals which send and receive data through a satellite, a method for adaptive error control coding of data in a downlink, the method comprising the steps of:

receiving at a destination terminal a downlink including light coded data transmitted by a satellite;

determining a first data error rate associated with said light coded data;

when said first data error rate exceeds a first threshold, commanding said originating terminal to subsequently select transmission of heavy coded data having a code rate less than said light coded data in said downlink to said destination terminal; and

when said first data error rate falls below a second threshold, commanding said originating terminal to set and address bit to a light coding value,

wherein said first threshold is different from said second threshold.

10. The method of claim 9, further comprising the step of applying, at a satellite, an inner code selected by said address bit to form light coded signals in the downlink.

14. In a satellite communications system including a Network Operation Center (NOC) and terminals which send and receive data through a satellite, a method for adaptive error control coding data in an uplink, the method comprising the steps of:

sending in uplink transmissions, by an originating terminal, light coded data addressed to a first destination terminal;

monitoring a power level associated with said uplink transmissions;

when said power level exceeds a first threshold, subsequently sending heavy coded data in said uplink transmissions; and

when said power level exceeds a second threshold, suspending, by said originating terminal, subsequent transmissions,

wherein said first threshold is different from said second threshold.

15. The method of claim 14, further comprising the steps of:

when said power level falls below a third threshold, subsequently sending light coded data in said uplink transmissions.

16. The method of claim 14, further comprising the steps of:

resuming transmissions, by said originating terminal, when said power level falls below a fourth threshold separated from said second threshold by a suspension hysteresis interval.

17. The method of claim 14, wherein said step of subsequently sending heavy coded data further comprising the step of sending a switch-to-heavy request and when said switch-to-heavy request is denied, commanding said originating terminal to enter standby mode.

18. The method of claim 16, wherein said step of resuming transmissions comprises resuming transmissions of heavy coded data from said originating terminal.

19. The method of claim 16, wherein said step of resuming transmissions comprises resuming transmissions of light coded data from said originating terminal.

20. The method of claim 16, wherein said step of suspending subsequent transmissions comprises suspending transmissions other than synchronization bursts.

21. The method of claim 14, wherein the step of subsequently sending heavy coded data comprises the step of applying an inner code generating said heavy coded data.

22. The method of claim 21, wherein the step of applying an inner code to generate said heavy coded data comprises applying an inner code having a code rate half that of light coded data.

23. The method of claim 15, wherein the step of subsequently sending light coded data comprises the step of applying an inner code generating said light coded data.

24. The method of claim 23, wherein the step of applying an inner code to generate said light coded data comprises applying an inner code having a code rate twice that of heavy coded data.