Mitigation of false co-channel uplink reception in a processing satellite communication system using stagger

• US 6,507,926 B1
• Filed: 03/16/1999
• Issued: 01/14/2003
• Est. Priority Date: 03/16/1999
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Wright, David A.
• Primary Examiner(s): Baker, Stephen M.
• Application Number:
  US09/270,572
• Time in Patent Office: 1,400 Days
• Field of Search: 714/776, 370/324, 370/328
• US Class Current: 714/776
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system

Abstract

The present invention provides a method and apparatus for preventing show-thru (and therefore misinsertion of unintended traffic) among uplink beams transmitted to a satellite. The method includes the steps of selecting (402) an uplink A stagger value, selecting an uplink B stagger value, coding (404) uplink A data to generate coded uplink A data, and coding (406) uplink B data to generate coded uplink B data. Subsequently, the method transmits (412) the coded uplink A data, staggered by the uplink A stagger value, in the uplink A and further transmits (414) the coded uplink B data, staggered by the uplink B stagger value, in the uplink B. During coding (404, 406), the method may use a full length error correcting code capable of correcting t errors. In such a case, the method generally selects an uplink B stagger value differing from the uplink A stagger value by more than t codeword symbols. Alternatively, the method, during coding (404, 406), may use a shortened error correcting code capable of correcting t errors. In such a case, the method generally selects an uplink B stagger value differing from the uplink A stagger value by at least one codeword symbol. The method is not limited to any particular number of uplink beams and may provide staggering for all same color uplink beams in a predetermined reuse pattern, for example.

Claims

1. A method for detecting show-thru in an uplink A due to an uplink B at a satellite receiver, the method comprising:

storing a plurality of stagger values associated with individual uplinks, including an uplink A stagger value;

establishing an uplink A decoding window according to said uplink A stagger value;

receiving cyclic error correction coded uplink A signals present at an uplink A receiver; and

decoding said uplink A signals to generate decoded uplink A data.

2. The method of claim 1, wherein said step of storing comprises storing a stagger value for each same color uplink in a predetermined reuse pattern.

3. The method of claim 1, wherein said decoding step further comprises the step of generating a decoder failure signal.

4. The method of claim 3, further comprising the step of discarding said decoded uplink A data when said decoder failure signal is asserted.

5. The method of claim 4, further comprising the step of accepting and relaying onward said decoded uplink A data when said decoder failure signal is unasserted.

6. The method of claim 4, wherein said step of decoding comprises Reed-Solomon decoding capable of correcting t errors.

7. The method of claim 6, wherein said step of decoding comprises decoding with a full length Reed-Solomon code.

8. The method of claim 7, wherein said storing step further comprises storing a plurality of stagger values differing by at least t codeword symbols and associated with individual uplinks.

9. The method of claim 6, wherein said step of decoding comprises decoding with a shortened Reed-Solomon code.

10. The method of claim 9, wherein said storing step further comprises storing a plurality of stagger values differing by at least one codeword symbol and associated with individual uplinks.

11. A method for minimizing the number of decoded co-channel interference affected signals decoded at a receiver, the method comprising:

coding signals from a first individual uplink using a cyclic error correction code;

coding signals from a second individual uplink using a cyclic error correction code; and

receiving signals from said first uplink at a first time;

receiving signals from said second uplink at a second time difference from said first time, wherein said first time and said second time are individually assigned to said first uplink and said second uplink.

12. The method of claim 11 further including the step of detecting a co-channel interference affected signal at a receiver.

13. The method of claim 12 further including the step of discarding a detected co-channel interference affected signal before decoding said co-channel interference affected signal.