Encoder and encoding method providing incremental redundancy
The present invention relates to an encoder for error correction code encoding input data words (D) into codewords (Z 1 , Z 2 ), comprising: an encoder input ( 1451 ) for receiving input data words (D) each comprising a first number K ldpc of information symbols, an encoding means ( 1452 ) for encoding an input data word (D) into a codeword (Z 1 , Z 2 , Z 3 , Z 4 ) such that a codeword comprises a basic codeword portion (B) including a data portion (D) and a basic parity portion (Pb) of a second number N ldpc −K ldpc of basic parity symbols, and an auxiliary codeword portion (A) including an auxiliary parity portion (Pa) of a third number M IR of auxiliary parity symbols, wherein said encoding means ( 14 ) is adapted i) for generating said basic codeword portion (B) from an input data word (D) according to a first code, wherein a basic parity symbol is generated by accumulating an information symbol at a parity symbol address determined according to a first address generation rule, and ii) for generating said auxiliary codeword portion (A) from an input data word (D) according to a second code, wherein an auxiliary parity symbol is generated by accumulating an information symbol m at a parity symbol address γ, wherein said parity symbol addresses γ are determined according to a second address generation rule N ldpc −K ldpc +{x+m mod G a ×Q IR } mod M IR if x>N ldpc −K ldpc , wherein x denotes the addresses of a parity symbol accumulator corresponding to the first information symbol of a group of size G a and Q IR is an auxiliary code rate dependent, predefined constant, and an encoder output ( 1454 ) for outputting said codewords (Z 1 , Z 2 ).
1. Encoder for error correction code encoding input data words (D) into codewords (Z 1 , Z 2 ), comprising:
an encoder input for receiving input data words (D) each comprising a first number K ldpc of information symbols,
an encoding means for encoding each of the input data words (D) into one of the codewords (Z 1 , Z 2 , Z 3 , Z 4 ) such that each of the codewords comprises a basic codeword portion (B) including a data portion (D) and a basic parity portion (Pb) of a second number N ldpc −K ldpc of basic parity symbols, and an auxiliary codeword portion (A) including an auxiliary parity portion (Pa) of a third number M IR of auxiliary parity symbols, wherein said encoding means is adapted
i) for generating said basic codeword portion (B) from one of the input data words (D) according to a first code, wherein each of the basic parity symbols is generated by accumulating an information symbol at a parity symbol address determined according to a first address generation rule, and
ii) for generating said auxiliary codeword portion (A) from said one of the input data words (D) according to a second code, wherein each of the auxiliary parity symbols is generated by accumulating an information symbol m at a parity symbol address γ, wherein said parity symbol addresses γ are determined according to a second address generation rule
N ldpc −K ldpc +{x+m mod G a ×Q IR } mod M IR if x≧N ldpc −K ldpc ,
wherein x denotes the addresses of a parity symbol accumulator corresponding to the first information symbol of a group of size G a and Q IR is an auxiliary code rate dependent, predefined constant, and
an encoder output for outputting said codewords (Z 1 , Z 2 ).
2. Encoder according to claim 1 ,
wherein said encoding means ( 1452 ) is adapted for generating said each of the auxiliary parity symbols by accumulating the information symbol m at the parity symbol address γ, wherein said parity symbol addresses γ are determined according to the first address generation rule
{ x+m mod G b ×Q ldpc } mod( N ldpc −K ldpc ) if x<N ldpc −K ldpc
wherein x denotes the addresses of a parity symbol accumulator corresponding to the first information symbol of a group of size G b and Q ldpc is a basic code rate dependent, predefined constant.
3. Encoder according to claim 1 or 2 ,
wherein G a =G b .
4. Encoder according to claim 3 ,
wherein G a =G b =360.
5. Encoder according to claim 1 ,
wherein said encoding means is adapted for blockwise generating said basic parity symbols and said auxiliary parity symbols by use of a group of subsequent information symbols,
wherein each information symbol i of said group of subsequent information symbols is accumulated at a set of different parity symbol addresses γ,
wherein the set of parity symbol addresses, at which the first information symbol of said group is accumulated, is taken from a predetermined address table and wherein the parity symbol addresses, at which the subsequent information symbols of said group are accumulated, are determined from said set of parity symbol addresses according to said first or said second address generation rule, respectively, and
wherein a separate set of parity symbol addresses is taken from said address table for generating each new block of basic parity symbols and auxiliary parity symbols.
6. Encoder according to claim 5 ,
wherein said encoding means is adapted for subsequently taking a new row of the following address table as a new set of different parity symbol addresses γ for accumulating a new group of subsequent information symbols, said address table for Q IR =12, M IR =4320, N ldpc =4320, Q ldpc =6 and a code rate identifier of 1/2 being
118
375
395
490
552
599
895
954
1005
1517
1576
1739
2030
194
1547
1598
1801
2291
3086
5097
5184
5413
140
238
253
1734
3972
4567
4573
5834
6055
243
378
919
1188
3265
3707
4176
4272
6174
201
1005
1033
1128
2945
3257
3898
4022
5194
202
727
782
1100
3117
3773
4683
5859
7. Encoder according to claim 5 ,
wherein said encoding means is adapted for subsequently taking a new row of the following address table as a new set of different parity symbol addresses γ for accumulating a new group of subsequent information symbols, said address table for Q IR =12, M IR =4320, N ldpc =4320, Q ldpc =5 and a code rate identifier of 7/12 being
125
447
543
634
864
1112
1124
1206
1268
1484
1568
1668
1672
105
605
821
1587
2609
3159
3333
4096
4237
4939
50
531
803
1595
2026
2683
4028
4729
5215
5261
226
410
810
1378
2195
4002
4456
4731
5724
5886
27
925
933
966
2134
2424
3165
3400
4488
5474
131
261
687
1079
2778
3519
4034
4809
6079
6109
207
1054
1706
1764
2079
3178
3439
3616
5029
5304
8. Encoder according to claim 5 ,
wherein said encoding means is adapted for subsequently taking a new row of the following address table as a new set of different parity symbol addresses γ for accumulating a new group of subsequent information symbols, said address table for Q IR =12, M IR =4320, N ldpc =4320, Q ldpc =4 and a code rate identifier of 2/3 being
15
253
313
501
563
582
865
911
977
1266
1276
1356
1427
256
743
982
1109
1441
2337
2387
2847
3209
3776
343
525
976
1102
1854
2900
3787
4669
4673
12
502
539
782
2980
3827
5035
5297
5576
556
593
1120
1420
2937
3800
4130
4662
4881
18
119
431
460
1548
1982
3230
4599
4992
178
253
416
771
2488
3026
4657
4815
5294
74
100
205
1214
1999
2412
2680
2952
5446
9. Encoder according to claim 5 ,
wherein said encoding means is adapted for subsequently taking a new row of the following address table as a new set of different parity symbol addresses γ for accumulating a new group of subsequent information symbols, said address table for Q IR =12, M IR =4320, N ldpc =4320, Q ldpc =3 and a code rate identifier of 3/4 being
109
116
136
141
178
238
250
503
566
723
978
1065
1068
113
191
586
1003
1496
1650
3564
5149
5210
219
426
583
1061
1146
1338
2094
2605
4627
329
429
576
855
1265
1810
3878
3884
4241
121
231
337
620
1896
2360
3027
3443
4297
199
216
676
831
1430
4431
4450
5094
223
560
686
713
3276
3286
4513
4612
632
944
1015
1043
2715
3381
3863
4586
171
365
514
882
2595
3456
4864
5136
10. Encoder according to claim 1 ,
wherein said basic codeword portion (B) is provided for regular decoding and said auxiliary codeword portion (A) is provided as incremental redundancy if regular decoding of the codeword by use of the basic codeword portion (B) is erroneous.
11. Transmitter for broadcasting data in a broadcasting system, comprising:
a data input for receiving at least one transmitter input data stream (I 1 , I 2 , . . . , In) segmented into input data words (D),
the encoder for error correction code encoding the input data words (D) into the codewords (Z 1 , Z 2 ) according to claim 1 ,
a data mapper ( 16 ) for mapping the codewords (Z 1 , Z 2 ) onto frames of a transmitter output data stream (O), and
a transmitter unit ( 18 ) for transmitting said transmitter output data stream (O).
12. Broadcasting system comprising the transmitter as claimed in claim 11 and one or more receivers for receiving data broadcast by said transmitter.
13. Encoding method for error correction code encoding input data words (D) into codewords (Z 1 , Z 2 ), comprising the steps of:
receiving input data words (D) each comprising a first number K ldpc of information symbols,
encoding each of the input data words (D) into one of the codewords (Z 1 , Z 2 , Z 3 , Z 4 ) such that each of the codewords comprises a basic codeword portion (B) including a data portion (D) and a basic parity portion (Pb) of a second number N ldpc −K ldpc of basic parity symbols, and an auxiliary codeword portion (A) including an auxiliary parity portion (Pa) of a third number M IR of auxiliary parity symbols,
generating said basic codeword portion (B) from one of the input data words (D) according to a first code, wherein each of the basic parity symbols is generated by accumulating an information symbol at a parity symbol address determined according to a first address generation rule,
generating said auxiliary codeword portion (A) from said one of the input data words (D) according to a second code, wherein each of the auxiliary parity symbols is generated by accumulating an information symbol m at a parity symbol address γ, wherein said parity symbol addresses γ are determined according to a second address generation rule
N ldpc −K ldpc +{x+m mod G a ×Q IR } mod M IR if x≧N ldpc −K ldpc ,
wherein x denotes the addresses of a parity symbol accumulator corresponding to the first information symbol of a group of size G a and Q IR is an auxiliary code rate dependent, predefined constant, and
outputting said codewords (Z 1 , Z 2 ).
14. A non-transitory computer program comprising program code means for causing a computer to carry out the steps of encoding and mapping of the method as claimed in claim 13 , when said computer program is carried out on a computer.
15. Transmission method for broadcasting data in a broadcasting system, comprising the steps of:
receiving at least one transmitter input data stream (I 1 I 2 , . . . , In) segmented into input data words (D),
the encoding method for error correction code encoding the input data words (D) into codewords (Z 1 , Z 2 ) according to claim 11 ,
mapping the codewords (Z 1 , Z 2 ) onto frames of a transmitter output data stream (O), and
transmitting said transmitter output data stream (O).