Method and apparatus for minimizing co-channel interference by scrambling
An approach is provided for minimizing co-channel interference in a communication system is disclosed. Non-header portions of frames, which are transmitted over the communication system, are scrambled according to respective different scrambling sequences. 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:
assigning a first scrambling sequence with a scrambler at a transmission station in the communications system, associated with a header or a pilot sequence of a first frame, to a first co-channel; and
assigning a second scrambling sequence with the scrambler at the transmission station in the communications system, associated with a header or a pilot sequence of a second frame, to a second co-channel that is adjacent to the first co-channel, wherein the scrambling sequences are based on Gold sequences with correspondingly different seeds, and the co-channels are among 17 co-channels, the seeds corresponding to the 17 co-channels are specified by Table A or Table B:
TABLE A
Seed X
Co-channel #
Decimal
Hex
1
1
00001
2
42348
0A56C
3
55204
0D7A4
4
57415
0E047
5
74129
12191
6
88022
157D6
7
111487
1B37F
8
112625
1B7F1
9
123876
1E3E4
10
137205
217F5
11
145515
2386B
12
151841
25121
13
166238
2895E
14
174767
2AAAF
15
183101
2CB3D
16
186848
2D9E0
17
188914
2E1F2
TABLE B
Co-
Seed X
channel #
Decimal
Hex
1
13
0000D
2
53
00035
3
70
00046
4
74
0004A
5
126
0007E
6
159
0009F
7
179
000B3
8
216
000D8
9
236
000EC
10
238
000EE
11
244
000F4
12
262
00106
13
278
00116
14
536
00218
15
628
00274
16
737
002E1
17
771
00303
wherein non-header portions of the frames are scrambled according to the respective different scrambling sequences.
2. A method according to claim 1 , further comprising the step of:
determining the seeds to minimize a worst cross-correlation condition.
3. A method according to claim 1 , wherein the communication system includes a satellite supporting digital broadcast and interactive applications.
4. A method according to claim 1 , wherein the header or the pilot sequence is used for acquiring or tracking carrier phase and carrier frequency.
5. A method according to claim 1 , wherein the header and the pilot sequence is used for acquiring or tracking carrier phase and carrier frequency.
6. A method according to claim 1 , further comprising the step of:
transmitting the frame according to a modulation scheme including Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), 8PSK, 16 Amplitude Phase Shift Keying (APSK), 32APSK, or a high order Quadrature Amplitude Modulation (QAM).
7. A method according to claim 1 , further comprising the step of:
modulating the frames according to different modulation schemes.
8. A method according to claim 1 , wherein each of the frames includes information encoded according to Low Density Parity Check (LDPC) coding.
9. An apparatus for minimizing co-channel interference in a communication system, comprising:
a scrambler configured to assign a first scrambling sequence, associated with a header or a pilot sequence of a first frame, to a first co-channel,
wherein the scrambler assigns a second scrambling sequence, associated with a header or a pilot sequence of a second frame, to a second co-channel that is adjacent to the first co-channel, wherein the scrambling sequences are based on Gold sequences with different seeds and the co-channels are among 17 co-channels, the seeds corresponding to the 17 co-channels are specified by Table A or Table B:
TABLE A
Seed X
Co-channel #
Decimal
Hex
1
1
00001
2
42348
0A56C
3
55204
0D7A4
4
57415
0E047
5
74129
12191
6
88022
157D6
7
111487
1B37F
8
112625
1B7F1
9
123876
1E3E4
10
137205
217F5
11
145515
2386B
12
151841
25121
13
166238
2895E
14
174767
2AAAF
15
183101
2CB3D
16
186848
2D9E0
17
188914
2E1F2
TABLE B
Co-
Seed X
channel #
Decimal
Hex
1
13
0000D
2
53
00035
3
70
00046
4
74
0004A
5
126
0007E
6
159
0009F
7
179
000B3
8
216
000D8
9
236
000EC
10
238
000EE
11
244
000F4
12
262
00106
13
278
00116
14
536
00218
15
628
00274
16
737
002E1
17
771
00303
wherein non-header portions of the frames are scrambled according to the respective scrambling sequences.
10. An apparatus according to claim 9 , further comprising:
means for determining the seeds to minimize a worst cross-correlation condition.
11. An apparatus according to claim 9 , wherein the communication system includes a satellite supporting digital broadcast and interactive applications.
12. An apparatus according to claim 9 , wherein the header or the pilot sequence is used for acquiring or tracking carrier phase and carrier frequency.
13. An apparatus according to claim 9 , wherein the header and the pilot sequence is used for acquiring or tracking carrier phase and carrier frequency.
14. An apparatus according to claim 9 , further comprising:
a transmitter configured to transmit the frame according to a modulation scheme including Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), 8PSK, 16 Amplitude Phase Shift Keying (APSK), 32APSK, or a high order Quadrature Amplitude Modulation (QAM).
15. An apparatus according to claim 9 , further comprising:
a modulator configured to modulate the frames according to different modulation schemes.
16. An apparatus according to claim 9 , wherein each of the frames includes information encoded according to Low Density Parity Check (LDPC) coding.
17. A method for communicating in a radio communication system, the method comprising the steps of:
transmitting, from a transmitter in the radio communication system, a plurality of frames over different communication channels established over the radio communication system, the communication channels being adjacent co-channels,
wherein each of the frames includes a header and a pilot sequence for synchronization of carrier phase and carrier frequency, and non-header portions of the frames are scrambled with a scrambler in the radio communication system according to respective different scrambling sequences, wherein the scrambling sequences are based on Gold sequences with different seeds and the co-channels are among 17 co-channels, the seeds corresponding to the 17 co-channels are specified by Table A or Table B:
TABLE A
Seed X
Co-channel #
Decimal
Hex
1
1
00001
2
42348
0A56C
3
55204
0D7A4
4
57415
0E047
5
74129
12191
6
88022
157D6
7
111487
1B37F
8
112625
1B7F1
9
123876
1E3E4
10
137205
217F5
11
145515
2386B
12
151841
25121
13
166238
2895E
14
174767
2AAAF
15
183101
2CB3D
16
186848
2D9E0
17
188914
2E1F2
TABLE B
Co-
Seed X
channel #
Decimal
Hex
1
13
0000D
2
53
00035
3
70
00046
4
74
0004A
5
126
0007E
6
159
0009F
7
179
000B3
8
216
000D8
9
236
000EC
10
238
000EE
11
244
000F4
12
262
00106
13
278
00116
14
536
00218
15
628
00274
16
737
002E1
17
771
00303
to minimize interference between the co-channels.
18. A method according to claim 17 , wherein each of the frames has a structure according to a Digital Video Broadcast (DVB) standard.
19. An apparatus for communicating in a radio communication system, comprising:
a transmitter configured to transmit a plurality of frames over different communication channels established over the radio communication system, wherein the communication channels are adjacent co-channels,
wherein each of the frames includes a header and a pilot sequence for synchronization of carrier phase and carrier frequency, and non-header portions of the frames are scrambled according to respective different scrambling sequences, wherein the scrambling sequences are based on Gold sequences with different seeds and the co-channels are among 17 co-channels, the seeds corresponding to the 17 co-channels are specified by Table A or Table B:
TABLE A
Seed X
Co-channel #
Decimal
Hex
1
1
00001
2
42348
0A56C
3
55204
0D7A4
4
57415
0E047
5
74129
12191
6
88022
157D6
7
111487
1B37F
8
112625
1B7F1
9
123876
1E3E4
10
137205
217F5
11
145515
2386B
12
151841
25121
13
166238
2895E
14
174767
2AAAF
15
183101
2CB3D
16
186848
2D9E0
17
188914
2E1F2
TABLE B
Co-
Seed X
channel #
Decimal
Hex
1
13
0000D
2
53
00035
3
70
00046
4
74
0004A
5
126
0007E
6
159
0009F
7
179
000B3
8
216
000D8
9
236
000EC
10
238
000EE
11
244
000F4
12
262
00106
13
278
00116
14
536
00218
15
628
00274
16
737
002E1
17
771
00303
to minimize interference between the co-channels.
20. An apparatus according to claim 19 , wherein each of the frames has a structure according to a Digital Video Broadcast (DVB) standard.
21. A method for communicating in a radio communication system, the method comprising the steps of:
receiving, at a receiver, a plurality of frames over different communication channels established over the radio communication system, the communication channels being adjacent co-channels,
wherein each of the frames includes a header and a pilot sequence for synchronization of carrier phase and carrier frequency, and non-header portions of the frames are scrambled according to respective different scrambling sequences, wherein the scrambling sequences are based on Gold sequences with different seeds and the co-channels are among 17 co-channels, the seeds corresponding to the 17 co-channels are specified by Table A or Table B:
TABLE A
Seed X
Co-channel #
Decimal
Hex
1
1
00001
2
42348
0A56C
3
55204
0D7A4
4
57415
0E047
5
74129
12191
6
88022
157D6
7
111487
1B37F
8
112625
1B7F1
9
123876
1E3E4
10
137205
217F5
11
145515
2386B
12
151841
25121
13
166238
2895E
14
174767
2AAAF
15
183101
2CB3D
16
186848
2D9E0
17
188914
2E1F2
TABLE B
Co-
Seed X
channel #
Decimal
Hex
1
13
0000D
2
53
00035
3
70
00046
4
74
0004A
5
126
0007E
6
159
0009F
7
179
000B3
8
216
000D8
9
236
000EC
10
238
000EE
11
244
000F4
12
262
00106
13
278
00116
14
536
00218
15
628
00274
16
737
002E1
17
771
00303
to minimize interference between the co-channels.
22. A method according to claim 21 , wherein each of the frames has a structure according to a Digital Video Broadcast (DVB) standard.
23. An apparatus for communicating in a radio communication system, comprising:
a receiver configured to receive a plurality of frames over different communication channels established over the radio communication system, wherein the communication channels are adjacent co-channels,
wherein each of the frames includes a header and a pilot sequence for synchronization of carrier phase and carrier frequency, and non-header portions of the frames are scrambled according to respective different scrambling sequences, wherein the scrambling sequences are based on Gold sequences with different seeds and the co-channels are among 17 co-channels, the seeds corresponding to the 17 co-channels are specified by Table A or Table B:
TABLE A
Seed X
Co-channel #
Decimal
Hex
1
1
00001
2
42348
0A56C
3
55204
0D7A4
4
57415
0E047
5
74129
12191
6
88022
157D6
7
111487
1B37F
8
112625
1B7F1
9
123876
1E3E4
10
137205
217F5
11
145515
2386B
12
151841
25121
13
166238
2895E
14
174767
2AAAF
15
183101
2CB3D
16
186848
2D9E0
17
188914
2E1F2
TABLE B
Co-
Seed X
channel #
Decimal
Hex
1
13
0000D
2
53
00035
3
70
00046
4
74
0004A
5
126
0007E
6
159
0009F
7
179
000B3
8
216
000D8
9
236
000EC
10
238
000EE
11
244
000F4
12
262
00106
13
278
00116
14
536
00218
15
628
00274
16
737
002E1
17
771
00303
to minimize interference between the co-channels.
24. An apparatus according to claim 23 , wherein each of the frames has a structure according to a Digital Video Broadcast (DVB) standard.