New upper bounds on the rate of low-density parity-check (LDPC) codes as a function of the minimum distance of the code are derived. These bounds are based on combinatorial arguments and linear programming. They improve on the previous bounds due to Burshtein et al. It is proved that at least for high rate LDPC codes have worse relative minimum distance than the one guaranteed by the Gilbert-Varshamov bound
{"title":"Upper bounds on the rate of LDPC codes as a function of minimum distance","authors":"Y. Ben-Haim, S. Litsyn","doi":"10.1109/TIT.2006.872972","DOIUrl":"https://doi.org/10.1109/TIT.2006.872972","url":null,"abstract":"New upper bounds on the rate of low-density parity-check (LDPC) codes as a function of the minimum distance of the code are derived. These bounds are based on combinatorial arguments and linear programming. They improve on the previous bounds due to Burshtein et al. It is proved that at least for high rate LDPC codes have worse relative minimum distance than the one guaranteed by the Gilbert-Varshamov bound","PeriodicalId":166130,"journal":{"name":"Proceedings. International Symposium on Information Theory, 2005. ISIT 2005.","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125432278","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 : 2005-12-01DOI: 10.1109/ISIT.2005.1523720
A. Lozano, S. Kulkarni
We study throughput scaling of an ad-hoc network where the nodes are restricted to move on vertical or horizontal lines on a square. A constant throughput is asymptotically achievable by the proposed scheduling algorithm, using in certain cases more than two hops strategies, without requiring each node to become the nearest neighbor of every other node. Hence the throughput result for one-dimensional mobility obtained by Diggavi et al. in Proc. IEEE ISIT, 2002 still holds under stricter mobility constraints
{"title":"A wireless network can achieve maximum throughput without each node meeting all others","authors":"A. Lozano, S. Kulkarni","doi":"10.1109/ISIT.2005.1523720","DOIUrl":"https://doi.org/10.1109/ISIT.2005.1523720","url":null,"abstract":"We study throughput scaling of an ad-hoc network where the nodes are restricted to move on vertical or horizontal lines on a square. A constant throughput is asymptotically achievable by the proposed scheduling algorithm, using in certain cases more than two hops strategies, without requiring each node to become the nearest neighbor of every other node. Hence the throughput result for one-dimensional mobility obtained by Diggavi et al. in Proc. IEEE ISIT, 2002 still holds under stricter mobility constraints","PeriodicalId":166130,"journal":{"name":"Proceedings. International Symposium on Information Theory, 2005. ISIT 2005.","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127475668","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 : 2005-10-31DOI: 10.1109/ISIT.2005.1523496
G. Dickins, M. Williams, L. Hanlen
Wireless communication occurs through continuous fields, over regions of space. Although the communication channel may be modelled in terms of infinite dimensional vector spaces, it is paramount to develop finite dimensional approximations for this channel. We extend previous work which examined the fundamental finite dimensionality of fields over a finite region of space to incorporate restricted angles of signal arrival. By considering a subspace of fields where direction of arrival of the field components, or source spatial distribution, is restricted we show the received field dimensionality is linearly related to the product of the radius of the region of interest and the angular restriction. This result provides a rigourous foundation for analysing the performance and capacity of MIMO systems in non isotropic environments. The proof is presented for the two dimensional case. It is apparent that this work can be extended to the case of three dimensions for a similar result
{"title":"On the dimensionality of spatial fields with restricted angle of arrival","authors":"G. Dickins, M. Williams, L. Hanlen","doi":"10.1109/ISIT.2005.1523496","DOIUrl":"https://doi.org/10.1109/ISIT.2005.1523496","url":null,"abstract":"Wireless communication occurs through continuous fields, over regions of space. Although the communication channel may be modelled in terms of infinite dimensional vector spaces, it is paramount to develop finite dimensional approximations for this channel. We extend previous work which examined the fundamental finite dimensionality of fields over a finite region of space to incorporate restricted angles of signal arrival. By considering a subspace of fields where direction of arrival of the field components, or source spatial distribution, is restricted we show the received field dimensionality is linearly related to the product of the radius of the region of interest and the angular restriction. This result provides a rigourous foundation for analysing the performance and capacity of MIMO systems in non isotropic environments. The proof is presented for the two dimensional case. It is apparent that this work can be extended to the case of three dimensions for a similar result","PeriodicalId":166130,"journal":{"name":"Proceedings. International Symposium on Information Theory, 2005. ISIT 2005.","volume":"380 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115477434","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 : 2005-10-31DOI: 10.1109/ISIT.2005.1523638
N. Ratnakar, G. Kramer
It is shown that one cannot always layer, or separate, channel and network coding for multicasting in deterministic relay networks with no interference. We call such networks Aref networks. The suboptimality of such layering in Aref networks is in contrast to the optimality of a similar layering in networks of discrete memoryless channels and certain networks of two-way channels
{"title":"On the separation of channel and network coding in aref networks","authors":"N. Ratnakar, G. Kramer","doi":"10.1109/ISIT.2005.1523638","DOIUrl":"https://doi.org/10.1109/ISIT.2005.1523638","url":null,"abstract":"It is shown that one cannot always layer, or separate, channel and network coding for multicasting in deterministic relay networks with no interference. We call such networks Aref networks. The suboptimality of such layering in Aref networks is in contrast to the optimality of a similar layering in networks of discrete memoryless channels and certain networks of two-way channels","PeriodicalId":166130,"journal":{"name":"Proceedings. International Symposium on Information Theory, 2005. ISIT 2005.","volume":"215 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114661059","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 : 2005-10-31DOI: 10.1109/ISIT.2005.1523324
Kwang Taik Kim, T. Berger
In the critical range O < D les Dc, the MSE rate-distortion function of a time-discrete stationary autoregressive Gaussian source is equal to that of a related time-discrete i.i.d. Gaussian source. This suggests that perhaps an optimum encoder should compute the related memoryless sequence from the given source sequence with memory and then use a code of rate R(D) to convey the memoryless sequence to the decoder with an MSE of D. In this scenario, the question is, "for D les Dc can a D-admissible code for the original source be obtained via the R-D coding of the innovations process and additional post-processing at the decoder without having to provide any additional information of positive rate?" We show that the answer of this question often is "No"
{"title":"Sending a lossy version of the innovations process is suboptimal in QG rate-distortion","authors":"Kwang Taik Kim, T. Berger","doi":"10.1109/ISIT.2005.1523324","DOIUrl":"https://doi.org/10.1109/ISIT.2005.1523324","url":null,"abstract":"In the critical range O < D les Dc, the MSE rate-distortion function of a time-discrete stationary autoregressive Gaussian source is equal to that of a related time-discrete i.i.d. Gaussian source. This suggests that perhaps an optimum encoder should compute the related memoryless sequence from the given source sequence with memory and then use a code of rate R(D) to convey the memoryless sequence to the decoder with an MSE of D. In this scenario, the question is, \"for D les Dc can a D-admissible code for the original source be obtained via the R-D coding of the innovations process and additional post-processing at the decoder without having to provide any additional information of positive rate?\" We show that the answer of this question often is \"No\"","PeriodicalId":166130,"journal":{"name":"Proceedings. International Symposium on Information Theory, 2005. ISIT 2005.","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121036987","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 : 2005-10-31DOI: 10.1109/ISIT.2005.1523674
R. Souza, G. Shamir, J. Garcia-Frías, Kai Xie
Non-systematic channel codes can have a significant advantage over systematic codes when utilizing redundancy left in the data for channel decoding. However, results previously attained show that even with such codes there is a performance gap to the theoretical limits. We propose a method that combines unequal energy allocation with source controlled decoding of non-systematic turbo codes. The method benefits from both (non-systematic codes and unequal energy allocation) to improve channel decoding performance in the presence of redundancy. Simulations demonstrate superior performance to the performances attained by each of the methods separately. A significant advantage is demonstrated over using non-systematic codes with equal energy allocation. At moderate (more practical) non-uniformities, there is also a clear advantage to the new method over unequal energy allocation with systematic turbo codes
{"title":"Non-systematic turbo coding with unequal energy allocation for nonuniform memoryless sources","authors":"R. Souza, G. Shamir, J. Garcia-Frías, Kai Xie","doi":"10.1109/ISIT.2005.1523674","DOIUrl":"https://doi.org/10.1109/ISIT.2005.1523674","url":null,"abstract":"Non-systematic channel codes can have a significant advantage over systematic codes when utilizing redundancy left in the data for channel decoding. However, results previously attained show that even with such codes there is a performance gap to the theoretical limits. We propose a method that combines unequal energy allocation with source controlled decoding of non-systematic turbo codes. The method benefits from both (non-systematic codes and unequal energy allocation) to improve channel decoding performance in the presence of redundancy. Simulations demonstrate superior performance to the performances attained by each of the methods separately. A significant advantage is demonstrated over using non-systematic codes with equal energy allocation. At moderate (more practical) non-uniformities, there is also a clear advantage to the new method over unequal energy allocation with systematic turbo codes","PeriodicalId":166130,"journal":{"name":"Proceedings. International Symposium on Information Theory, 2005. ISIT 2005.","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121336607","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 : 2005-10-31DOI: 10.1109/ISIT.2005.1523701
C. Burnet, W. Cowley
This paper presents the performance for turbo equalization of ISI caused by a nonlinear satellite channel. Mutual information transfer characteristics are used to highlight the performance of the proposed turbo equalization and confirm convergence of the iterative scheme. An equivalent SNR model for the nonlinear channel is presented which shows direct correspondence between the linear and nonlinear channels. The nonlinear channel equalizer is based on a soft interference cancellation approach which has linear complexity with modulation order and channel memory
{"title":"Performance analysis of turbo equalization for nonlinear channels","authors":"C. Burnet, W. Cowley","doi":"10.1109/ISIT.2005.1523701","DOIUrl":"https://doi.org/10.1109/ISIT.2005.1523701","url":null,"abstract":"This paper presents the performance for turbo equalization of ISI caused by a nonlinear satellite channel. Mutual information transfer characteristics are used to highlight the performance of the proposed turbo equalization and confirm convergence of the iterative scheme. An equivalent SNR model for the nonlinear channel is presented which shows direct correspondence between the linear and nonlinear channels. The nonlinear channel equalizer is based on a soft interference cancellation approach which has linear complexity with modulation order and channel memory","PeriodicalId":166130,"journal":{"name":"Proceedings. International Symposium on Information Theory, 2005. ISIT 2005.","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127087127","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 : 2005-10-31DOI: 10.1109/ISIT.2005.1523663
Chandra Nair, E. Ordentlich, T. Weissman
Recent work by Ordentlich and Weissman put forth a new approach for bounding the entropy rate of a hidden Markov process via the construction of a related Markov process. We use this approach to study the behavior of the filtering error probability and the entropy rate of a hidden Markov process in the rare transitions regime. In this paper, we restrict our attention to the case of a two state Markov chain that is corrupted by a binary symmetric channel. Using this approach we recover the results on the optimal filtering error probability of Khasminskii and Zeitouni. In addition, this approach sheds light on the terms that appear in the expression for the optimal filtering error probability. We then use this approach to obtain tight estimates of the entropy rate of the process in the rare transitions regime. This leads to tight estimates on the capacity of the Gilbert-Elliot channel in the rare transitions regime
{"title":"Asymptotic filtering and entropy rate of a hidden Markov process in the rare transitions regime","authors":"Chandra Nair, E. Ordentlich, T. Weissman","doi":"10.1109/ISIT.2005.1523663","DOIUrl":"https://doi.org/10.1109/ISIT.2005.1523663","url":null,"abstract":"Recent work by Ordentlich and Weissman put forth a new approach for bounding the entropy rate of a hidden Markov process via the construction of a related Markov process. We use this approach to study the behavior of the filtering error probability and the entropy rate of a hidden Markov process in the rare transitions regime. In this paper, we restrict our attention to the case of a two state Markov chain that is corrupted by a binary symmetric channel. Using this approach we recover the results on the optimal filtering error probability of Khasminskii and Zeitouni. In addition, this approach sheds light on the terms that appear in the expression for the optimal filtering error probability. We then use this approach to obtain tight estimates of the entropy rate of the process in the rare transitions regime. This leads to tight estimates on the capacity of the Gilbert-Elliot channel in the rare transitions regime","PeriodicalId":166130,"journal":{"name":"Proceedings. International Symposium on Information Theory, 2005. ISIT 2005.","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127195550","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 : 2005-10-31DOI: 10.1109/ISIT.2005.1523348
Matthew J. M. Peacock, I. Collings, M. Honig
We consider a large system analysis of the minimum-mean-squared-error (MMSE) receiver and the adaptive least-squares (ALS) receiver for a class of random matrix channels. We give a relationship between the transient/steady-state SINR of the ALS and the MMSE receivers. We demonstrate that for a particular ratio of receive to transmit dimensions and window shape, all channels which have the same MMSE SINR, would have an identical transient ALS SINR response
{"title":"A relationship between the SINR of MMSE and ALS receivers","authors":"Matthew J. M. Peacock, I. Collings, M. Honig","doi":"10.1109/ISIT.2005.1523348","DOIUrl":"https://doi.org/10.1109/ISIT.2005.1523348","url":null,"abstract":"We consider a large system analysis of the minimum-mean-squared-error (MMSE) receiver and the adaptive least-squares (ALS) receiver for a class of random matrix channels. We give a relationship between the transient/steady-state SINR of the ALS and the MMSE receivers. We demonstrate that for a particular ratio of receive to transmit dimensions and window shape, all channels which have the same MMSE SINR, would have an identical transient ALS SINR response","PeriodicalId":166130,"journal":{"name":"Proceedings. International Symposium on Information Theory, 2005. ISIT 2005.","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125295392","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 : 2005-10-31DOI: 10.1109/ISIT.2005.1523656
Jun Chen, C. Tian, T. Berger, S. Hemami
We propose a new class of universal multiple description lattice quantizers based on the method of quantization splitting. For Gaussian sources and squared error distortion measure, our scheme can achieve the whole multiple description rate-distortion region, as the dimension of the (optimal) lattice quantizers becomes large
{"title":"A new class of universal multiple description lattice quantizers","authors":"Jun Chen, C. Tian, T. Berger, S. Hemami","doi":"10.1109/ISIT.2005.1523656","DOIUrl":"https://doi.org/10.1109/ISIT.2005.1523656","url":null,"abstract":"We propose a new class of universal multiple description lattice quantizers based on the method of quantization splitting. For Gaussian sources and squared error distortion measure, our scheme can achieve the whole multiple description rate-distortion region, as the dimension of the (optimal) lattice quantizers becomes large","PeriodicalId":166130,"journal":{"name":"Proceedings. International Symposium on Information Theory, 2005. ISIT 2005.","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115051385","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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