Pub Date : 2001-06-24DOI: 10.1109/ISIT.2001.936096
M. Fossorier
In this work, reliability based decoding is combined with belief propagation (BP) decoding for low-density parity check (LDPC) codes. At each iteration, the soft output values delivered by the BP algorithm are used as reliability values to perform reduced complexity soft decision decoding of the code considered. This approach allows to bridge the error performance gap between BP decoding which remains suboptimum, and maximum likelihood decoding (MLD) which is too complex to be implemented for the codes considered. A stopping criterion which reduces the average number of iterations at the expense of very little performance degradation is also proposed for this combined decoding approach. Simulations results for several Gallager LDPC codes and different set cyclic (DSC) codes of hundreds of information bits are given and elaborated.
{"title":"Iterative reliability based decoding of LDPC codes","authors":"M. Fossorier","doi":"10.1109/ISIT.2001.936096","DOIUrl":"https://doi.org/10.1109/ISIT.2001.936096","url":null,"abstract":"In this work, reliability based decoding is combined with belief propagation (BP) decoding for low-density parity check (LDPC) codes. At each iteration, the soft output values delivered by the BP algorithm are used as reliability values to perform reduced complexity soft decision decoding of the code considered. This approach allows to bridge the error performance gap between BP decoding which remains suboptimum, and maximum likelihood decoding (MLD) which is too complex to be implemented for the codes considered. A stopping criterion which reduces the average number of iterations at the expense of very little performance degradation is also proposed for this combined decoding approach. Simulations results for several Gallager LDPC codes and different set cyclic (DSC) codes of hundreds of information bits are given and elaborated.","PeriodicalId":433761,"journal":{"name":"Proceedings. 2001 IEEE International Symposium on Information Theory (IEEE Cat. No.01CH37252)","volume":"371 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124652424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-06-24DOI: 10.1109/ISIT.2001.936169
A. Mantravadi, V. Veeravalli
We consider the analysis of linear MMSE detection in a CDMA system that employs random spreading sequences. The key features of the analysis are that the users are allowed to be completely asynchronous and the chip waveform is assumed to be the ideal band-limited sine waveform. We show that the asymptotic signal to interference ratio (SIR) at the detector output is the same as that in an equivalent chip synchronous system. Hence, synchronous analyses can provide useful guidelines for the performance in asynchronous band-limited systems.
{"title":"Asymptotic analysis of MMSE detection in asynchronous CDMA systems: an equivalence result","authors":"A. Mantravadi, V. Veeravalli","doi":"10.1109/ISIT.2001.936169","DOIUrl":"https://doi.org/10.1109/ISIT.2001.936169","url":null,"abstract":"We consider the analysis of linear MMSE detection in a CDMA system that employs random spreading sequences. The key features of the analysis are that the users are allowed to be completely asynchronous and the chip waveform is assumed to be the ideal band-limited sine waveform. We show that the asymptotic signal to interference ratio (SIR) at the detector output is the same as that in an equivalent chip synchronous system. Hence, synchronous analyses can provide useful guidelines for the performance in asynchronous band-limited systems.","PeriodicalId":433761,"journal":{"name":"Proceedings. 2001 IEEE International Symposium on Information Theory (IEEE Cat. No.01CH37252)","volume":"157 9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130508573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-06-24DOI: 10.1109/ISIT.2001.935910
A. Barg, G. Zémor
We show that expander codes attain the capacity of the binary symmetric channel under iterative decoding. The error probability has a positive exponent for all rates between 0 and channel capacity. The decoding complexity grows linearly with code length.
{"title":"Error exponents of expander codes","authors":"A. Barg, G. Zémor","doi":"10.1109/ISIT.2001.935910","DOIUrl":"https://doi.org/10.1109/ISIT.2001.935910","url":null,"abstract":"We show that expander codes attain the capacity of the binary symmetric channel under iterative decoding. The error probability has a positive exponent for all rates between 0 and channel capacity. The decoding complexity grows linearly with code length.","PeriodicalId":433761,"journal":{"name":"Proceedings. 2001 IEEE International Symposium on Information Theory (IEEE Cat. No.01CH37252)","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129090075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-06-24DOI: 10.1109/ISIT.2001.935927
Z. Kukorelly, K. Zeger
We consider two-dimensional binary codes whose bits lie on a hexagonal lattice and satisfy a (d,k) constraint in six directions. We prove that the capacity is zero if k=d+2 and give positive lower bounds on the capacity for k/spl ges/4[d/2]+1.
{"title":"The capacity of some hexagonal (d,k)-constraints","authors":"Z. Kukorelly, K. Zeger","doi":"10.1109/ISIT.2001.935927","DOIUrl":"https://doi.org/10.1109/ISIT.2001.935927","url":null,"abstract":"We consider two-dimensional binary codes whose bits lie on a hexagonal lattice and satisfy a (d,k) constraint in six directions. We prove that the capacity is zero if k=d+2 and give positive lower bounds on the capacity for k/spl ges/4[d/2]+1.","PeriodicalId":433761,"journal":{"name":"Proceedings. 2001 IEEE International Symposium on Information Theory (IEEE Cat. No.01CH37252)","volume":"847 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120864400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-06-24DOI: 10.1109/ISIT.2001.935949
P. Gaborit, Jon-Lark Kim, V. Pless
We decode the binary Reed-Muller [32,16,8] code R(2,5) by hand by two methods. One, the representation decoding method, is the analogue of the method used to decode the Golay code. The other is the new syndrome decoding method. We also decode R(2,5) by machine using information sets.
{"title":"Decoding binary R(2,5) by hand and by machine","authors":"P. Gaborit, Jon-Lark Kim, V. Pless","doi":"10.1109/ISIT.2001.935949","DOIUrl":"https://doi.org/10.1109/ISIT.2001.935949","url":null,"abstract":"We decode the binary Reed-Muller [32,16,8] code R(2,5) by hand by two methods. One, the representation decoding method, is the analogue of the method used to decode the Golay code. The other is the new syndrome decoding method. We also decode R(2,5) by machine using information sets.","PeriodicalId":433761,"journal":{"name":"Proceedings. 2001 IEEE International Symposium on Information Theory (IEEE Cat. No.01CH37252)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114351354","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-06-24DOI: 10.1109/ISIT.2001.936195
James S. K. Tee, Desmond P. Taylor
In a previous paper (see Proc. IEEE GLOBECOM Conference, vol.2, p.842-6, Nov. 2000) we applied the MAP-SPC decoding technique to the decoding of short Hamming codes. In this paper, further results are presented for longer Hamming codes. This technique achieves performance gains of approximately 1 dB and 7 dB over hard algebraic decoding in the AWGN and fading channel respectively. Although this decoding strategy is suboptimal compared to ML soft decision decoding, its complexity is relatively low and grows linearly with increasing block length. In addition, the decoder is simple to implement.
{"title":"Suboptimal SISO decoding of systematic binary algebraic block codes","authors":"James S. K. Tee, Desmond P. Taylor","doi":"10.1109/ISIT.2001.936195","DOIUrl":"https://doi.org/10.1109/ISIT.2001.936195","url":null,"abstract":"In a previous paper (see Proc. IEEE GLOBECOM Conference, vol.2, p.842-6, Nov. 2000) we applied the MAP-SPC decoding technique to the decoding of short Hamming codes. In this paper, further results are presented for longer Hamming codes. This technique achieves performance gains of approximately 1 dB and 7 dB over hard algebraic decoding in the AWGN and fading channel respectively. Although this decoding strategy is suboptimal compared to ML soft decision decoding, its complexity is relatively low and grows linearly with increasing block length. In addition, the decoder is simple to implement.","PeriodicalId":433761,"journal":{"name":"Proceedings. 2001 IEEE International Symposium on Information Theory (IEEE Cat. No.01CH37252)","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114873255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-06-24DOI: 10.1109/ISIT.2001.936144
H. Sawaya, J. Boutros
This paper deals with multilevel coded modulations (MLC) based on ASK and PSK constellations for the AWGN channel. Under multistage decoding (MSD) and when block partitioning is applied to an asymmetric constellation, we show that the capacity of the modulation can be attained using constituent codes with equal signalling rates at each level. For finite code length N, performance is derived analytically by evaluating Gallager's coding exponent.
{"title":"Multilevel coded modulations based on asymmetric constellations","authors":"H. Sawaya, J. Boutros","doi":"10.1109/ISIT.2001.936144","DOIUrl":"https://doi.org/10.1109/ISIT.2001.936144","url":null,"abstract":"This paper deals with multilevel coded modulations (MLC) based on ASK and PSK constellations for the AWGN channel. Under multistage decoding (MSD) and when block partitioning is applied to an asymmetric constellation, we show that the capacity of the modulation can be attained using constituent codes with equal signalling rates at each level. For finite code length N, performance is derived analytically by evaluating Gallager's coding exponent.","PeriodicalId":433761,"journal":{"name":"Proceedings. 2001 IEEE International Symposium on Information Theory (IEEE Cat. No.01CH37252)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127657668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-06-24DOI: 10.1109/ISIT.2001.935907
T.H. Chan, R. Yeung
Factorization of positive functions into products of local functions is crucial in graphical modeling. In this paper, the problem of factorizing a positive function P is investigated. When P does not have a simple factorization, an approximation of P by a simple function is given by a computationally efficient algorithm.
{"title":"On factorization of positive functions","authors":"T.H. Chan, R. Yeung","doi":"10.1109/ISIT.2001.935907","DOIUrl":"https://doi.org/10.1109/ISIT.2001.935907","url":null,"abstract":"Factorization of positive functions into products of local functions is crucial in graphical modeling. In this paper, the problem of factorizing a positive function P is investigated. When P does not have a simple factorization, an approximation of P by a simple function is given by a computationally efficient algorithm.","PeriodicalId":433761,"journal":{"name":"Proceedings. 2001 IEEE International Symposium on Information Theory (IEEE Cat. No.01CH37252)","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126258311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-06-24DOI: 10.1109/ISIT.2001.936143
P. Moqvist, T. Aulin
Using signal energy criteria, the best lower-dimensional representation of a signal set is given by its principal components (PC). A comparison with a previous method by Huber and Liu (1989) shows that the differences are small. However, the minimum distance loss in CPM is generally larger with the PC method; thus it is mainly of theoretical interest. Still, it provides an alternative to Gram-Schmidt approaches, e.g. in simulations.
{"title":"Signal space dimension reduction for AWGN channels with application to CPM","authors":"P. Moqvist, T. Aulin","doi":"10.1109/ISIT.2001.936143","DOIUrl":"https://doi.org/10.1109/ISIT.2001.936143","url":null,"abstract":"Using signal energy criteria, the best lower-dimensional representation of a signal set is given by its principal components (PC). A comparison with a previous method by Huber and Liu (1989) shows that the differences are small. However, the minimum distance loss in CPM is generally larger with the PC method; thus it is mainly of theoretical interest. Still, it provides an alternative to Gram-Schmidt approaches, e.g. in simulations.","PeriodicalId":433761,"journal":{"name":"Proceedings. 2001 IEEE International Symposium on Information Theory (IEEE Cat. No.01CH37252)","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126377355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-06-24DOI: 10.1109/ISIT.2001.935947
S. Sakata
Compound-error-correcting codes are codes designed to correct some mixtures of random and burst errors called compound errors. Their compound-error-correction capabilities are measured with respect to a generalized metric introduced by M. Hamada (1997) and discussed by M. Kurihara (2000) recently. We propose step-by-step decoding method for linear compound-error-correcting codes as a generalization of the known step-by-step decoding of linear random-error-correcting codes.
{"title":"Step-by-step decoding of compound-error-correcting codes","authors":"S. Sakata","doi":"10.1109/ISIT.2001.935947","DOIUrl":"https://doi.org/10.1109/ISIT.2001.935947","url":null,"abstract":"Compound-error-correcting codes are codes designed to correct some mixtures of random and burst errors called compound errors. Their compound-error-correction capabilities are measured with respect to a generalized metric introduced by M. Hamada (1997) and discussed by M. Kurihara (2000) recently. We propose step-by-step decoding method for linear compound-error-correcting codes as a generalization of the known step-by-step decoding of linear random-error-correcting codes.","PeriodicalId":433761,"journal":{"name":"Proceedings. 2001 IEEE International Symposium on Information Theory (IEEE Cat. No.01CH37252)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122259765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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