Method and apparatus for minimizing co-channel interference
An approach is provided for minimizing co-channel interference in a communication system is disclosed. A header of a first frame is scrambled based on a first unique word. A header of a second frame is scrambled based on a second unique word. The first frame including the corresponding scrambled header and the second frame including the corresponding scrambled header are transmitted, respectively, over adjacent co-channels of the communication system. Each of the frames further includes a payload and a pilot block. The payload and the pilot block of the first frame are scrambled based on a first scrambling sequence. The payload and the pilot block of the second frame are scrambled based on a second scrambling sequence. The above arrangement is particularly suited to a digital satellite broadcast and interactive system.
1. A method for minimizing co-channel interference in a communication system, the method comprising the steps of:
scrambling a header of a first frame based on a first unique word;
scrambling a payload and a pilot block of the first frame based on a first scrambling sequence;
scrambling a header of a second frame based on a second unique word; and
scrambling a payload and a pilot block of the second frame based on a second scrambling sequence,
wherein the first frame including the corresponding scrambled header and the second frame including the corresponding scrambled header are transmitted, respectively, over adjacent co-channels of the communication system.
2. A method according to claim 1 , further comprising the step of:
transmitting information associated with the unique words and the scrambling sequences over a default carrier to a receiver within the communication system.
3. A method according to claim 1 , further comprising the step of:
generating a plurality of sets of unique words and scrambling sequences corresponding to carriers supported by the communication system.
4. A method according to claim 3 , wherein the quantity of sets is a predetermined value.
5. A method according to claim 4 , wherein a portion of the sets are stored at a receiver, the method further comprising the step of:
instructing the receiver about which of the stored sets to use.
6. A method according to claim 4 , wherein a portion of the sets are stored at a receiver, and the receiver determines a valid set for a particular carrier from the stored sets.
7. A method according to claim 1 , wherein the sets are stored in a database coupled to a receiver, and the receiver includes a cache configured to store a portion of the sets.
8. A method according to claim 7 , wherein a portion of the sets are stored at a receiver, the method further comprising the step of:
instructing the receiver to update the cache.
9. A method according to claim 1 , wherein the scrambling sequences are based on Gold sequences.
10. A method according to claim 1 , wherein the communication system includes a satellite supporting digital broadcast and interactive applications.
11. A method according to claim 1 , further comprising the step of:
transmitting each of the frames according to a modulation scheme including one of Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), BPSK, 16 Amplitude Phase Shift Keying (APSK), 32APSK, and a high order Quadrature Amplitude Modulation (QAM).
12. A method according to claim 1 , wherein each of the frames includes information encoded according to Low Density Parity Check (LDPC) coding.
13. A computer-readable medium bearing instructions for minimizing co-channel interference in a communication system, said instruction, being arranged, upon execution, to cause one or more processors to perform the method of claim 1 .
14. An apparatus for minimizing co-channel interference in a communication system, comprising:
a scrambler configured to scramble a header of a first frame based on a first unique word, and to scramble a header of a second frame based on a second unique word, the scrambler being further configured to scramble a payload and a pilot block of the first frame based on a first scrambling sequence and to scramble a payload and a pilot block of the second frame based on a second scrambling sequence,
wherein the first frame including the corresponding scrambled header and the second frame including the corresponding scrambled header are transmitted, respectively, over adjacent co-channels of the communication system.
15. An apparatus according to claim 14 , wherein information associated with the unique words and the scrambling sequences is transmitted over a default carrier to a receiver within the communication system.
16. An apparatus according to claim 14 , wherein the scrambler generates a plurality of sets of unique words and scrambling sequences corresponding to carriers supported by the communication system.
17. An apparatus according to claim 16 , wherein the quantity of sets is a predetermined value.
18. An apparatus according to claim 17 , wherein a portion of the sets are stored at a receiver, and the receiver is instructed about which of the stored sets to use.
19. An apparatus according to claim 17 , wherein a portion of the sets are stored at a receiver, and the receiver determines a valid set for a particular carrier from the stored sets.
20. An apparatus according to claim 14 , wherein the sets are stored in a database coupled to a receiver, and the receiver includes a cache configured to store a portion of the sets.
21. An apparatus according to claim 20 , wherein a portion of the sets are stored at a receiver, and the receiver is instructed to update the cache.
22. An apparatus according to claim 14 , wherein the scrambling sequences are based on Gold sequences.
23. An apparatus according to claim 14 , wherein the communication system includes a satellite supporting digital broadcast and interactive applications.
24. An apparatus according to claim 14 , further comprising:
a modulator configured to modulate the frames according to a modulation scheme including one of Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), 8PSK, 16 Amplitude Phase Shift Keying (APSK), 32APSK, and a high order Quadrature Amplitude Modulation (QAM).
25. An apparatus according to claim 14 , wherein each of the frames includes information encoded according to Low Density Parity Check (LDPC) coding.
26. A method of communicating comprising the steps of:
tuning to a default carrier to receive scrambling information, wherein the scrambling information includes a unique word and a scrambling sequence corresponding to a particular carrier among a plurality of adjacent carriers, the unique word and the scrambling sequence being selected to minimize co-channel interference with respect to the adjacent carriers;
tuning to the particular carrier for receiving a scrambled frame including a header, a payload, and a pilot block;
descrambling the header with the unique word; and
descrambling the payload and the pilot block with the scrambling sequence.
27. A method according to claim 26 , wherein the scrambling information is one of a plurality of sets of scrambling information corresponding to different ones of the adjacent carriers.
28. A method according to claim 27 , wherein the quantity of sets is a predetermined value.
29. A method according to claim 27 , further comprising:
receiving a portion of the sets of scrambling information; and
storing the portion of the sets of scrambling information in a cache.
30. A method according to claim 27 , further comprising:
tuning to another one of the carriers; and
determining a valid set from the stored sets of scrambling information for the one carrier.
31. A method according to claim 27 , further comprising:
receiving the sets of scrambling information; and
storing the sets of scrambling information in a database.
32. A method according to claim 31 , further comprising:
storing a portion of the sets of scrambling information in a cache.
33. A method according to claim 32 , further comprising:
receiving a command to update the cache.
34. A method according to claim 26 , wherein the scrambling sequences are based on Gold sequences.
35. A method according to claim 26 , wherein the communication system includes a satellite supporting digital broadcast and interactive applications.
36. A method according to claim 26 , wherein the unique word has a length identical with the header, the scrambled header in the scrambled frame being determined based on an exclusive-OR function with the unique word.
37. A computer-readable medium bearing instructions for communicating in a communication system, said instruction, being arranged, upon execution, to cause one or more processors to perform the method of claim 26 .