Pub Date : 2012-12-01DOI: 10.1109/ITW.2012.6404746
V. Kostina, S. Verdú
We revisit the dilemma of whether one should or should not code when operating under delay constraints. In those curious cases when the source and the channel are probabilistically matched so that symbol-by-symbol coding is optimal in terms of the average distortion achieved, we show that it also achieves the dispersion of joint source-channel coding. Moreover, even in the absence of such probabilistic matching between the source and the channel, symbol-by-symbol transmission, though asymptotically suboptimal, might outperform not only separate source-channel coding but also the best known random-coding joint source-channel coding achievability bound in the finite blocklength regime.
{"title":"To code or not to code: Revisited","authors":"V. Kostina, S. Verdú","doi":"10.1109/ITW.2012.6404746","DOIUrl":"https://doi.org/10.1109/ITW.2012.6404746","url":null,"abstract":"We revisit the dilemma of whether one should or should not code when operating under delay constraints. In those curious cases when the source and the channel are probabilistically matched so that symbol-by-symbol coding is optimal in terms of the average distortion achieved, we show that it also achieves the dispersion of joint source-channel coding. Moreover, even in the absence of such probabilistic matching between the source and the channel, symbol-by-symbol transmission, though asymptotically suboptimal, might outperform not only separate source-channel coding but also the best known random-coding joint source-channel coding achievability bound in the finite blocklength regime.","PeriodicalId":325771,"journal":{"name":"2012 IEEE Information Theory Workshop","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114806416","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 : 2012-12-01DOI: 10.1109/ITW.2012.6404758
Md. Zahurul I. Sarkar, T. Ratnarajah
We consider the problem of secret communication through cognitive relay assisted interference channels where the secondary users are allowed to transmit simultaneously with the primary users over the same channel in the presence of an eavesdropper. At first, we investigate the effect of diversity in enhancing security of the cognitive interference channels with multiple relays. Then, the performance of cognitive relay beamforming system is optimized in such a way that the eavesdropper gets zero bits of information maintaining interferences at the primary receiver under a certain threshold. Finally, we characterize secrecy rate at the primary and secondary receivers compensating interferences using zero-forcing (ZF) precoding at the cognitive relay.
{"title":"Aspect of security in the cognitive relay assisted interference channels","authors":"Md. Zahurul I. Sarkar, T. Ratnarajah","doi":"10.1109/ITW.2012.6404758","DOIUrl":"https://doi.org/10.1109/ITW.2012.6404758","url":null,"abstract":"We consider the problem of secret communication through cognitive relay assisted interference channels where the secondary users are allowed to transmit simultaneously with the primary users over the same channel in the presence of an eavesdropper. At first, we investigate the effect of diversity in enhancing security of the cognitive interference channels with multiple relays. Then, the performance of cognitive relay beamforming system is optimized in such a way that the eavesdropper gets zero bits of information maintaining interferences at the primary receiver under a certain threshold. Finally, we characterize secrecy rate at the primary and secondary receivers compensating interferences using zero-forcing (ZF) precoding at the cognitive relay.","PeriodicalId":325771,"journal":{"name":"2012 IEEE Information Theory Workshop","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121858007","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 : 2012-09-03DOI: 10.1109/ITW.2012.6404764
Mostafa Monemizadeh, G. Hodtani
We study the two-user discrete memoryless compound multiple access channel (MAC) with common message and two specially correlated channel states each known non-causally by one of the encoders. Two channel states are correlated in the sense of Slepian-Wolf (SW) in which two correlated states are modeled by three independent states: a common state and two private states. By using superposition coding, binning scheme and jointly decoding, we propose several achievable rates for various cases of the two-user compound MAC with non-causal Slepian-Wolf channel states available at encoders and common message or conferencing encoders. Also, we show that the obtained achievable rate regions are optimal when perfect states are known at both decoders as well.
{"title":"Achievable rate regions for compound multiple access channel with channel state information","authors":"Mostafa Monemizadeh, G. Hodtani","doi":"10.1109/ITW.2012.6404764","DOIUrl":"https://doi.org/10.1109/ITW.2012.6404764","url":null,"abstract":"We study the two-user discrete memoryless compound multiple access channel (MAC) with common message and two specially correlated channel states each known non-causally by one of the encoders. Two channel states are correlated in the sense of Slepian-Wolf (SW) in which two correlated states are modeled by three independent states: a common state and two private states. By using superposition coding, binning scheme and jointly decoding, we propose several achievable rates for various cases of the two-user compound MAC with non-causal Slepian-Wolf channel states available at encoders and common message or conferencing encoders. Also, we show that the obtained achievable rate regions are optimal when perfect states are known at both decoders as well.","PeriodicalId":325771,"journal":{"name":"2012 IEEE Information Theory Workshop","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122802650","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 : 2012-09-01DOI: 10.1109/ITW.2012.6404734
W. Kotłowski, P. Grünwald
The paper considers sequential prediction of individual sequences with log loss using an exponential family of distributions. We first show that the commonly used maximum likelihood strategy is suboptimal and requires an additional assumption about boundedness of the data sequence. We then show that both problems can be be addressed by adding the currently predicted outcome to the calculation of the maximum likelihood, followed by normalization of the distribution. The strategy obtained in this way is known in the literature as the sequential normalized maximum likelihood (SNML) strategy. We show that for general exponential families, the regret is bounded by the familiar (k/2)logn and thus optimal up to O(1). We also introduce an approximation to SNML, flattened maximum likelihood, much easier to compute that SNML itself, while retaining the optimal regret under some additional assumptions. We finally discuss the relationship to the Bayes strategy with Jeffreys' prior.
{"title":"Sequential normalized maximum likelihood in log-loss prediction","authors":"W. Kotłowski, P. Grünwald","doi":"10.1109/ITW.2012.6404734","DOIUrl":"https://doi.org/10.1109/ITW.2012.6404734","url":null,"abstract":"The paper considers sequential prediction of individual sequences with log loss using an exponential family of distributions. We first show that the commonly used maximum likelihood strategy is suboptimal and requires an additional assumption about boundedness of the data sequence. We then show that both problems can be be addressed by adding the currently predicted outcome to the calculation of the maximum likelihood, followed by normalization of the distribution. The strategy obtained in this way is known in the literature as the sequential normalized maximum likelihood (SNML) strategy. We show that for general exponential families, the regret is bounded by the familiar (k/2)logn and thus optimal up to O(1). We also introduce an approximation to SNML, flattened maximum likelihood, much easier to compute that SNML itself, while retaining the optimal regret under some additional assumptions. We finally discuss the relationship to the Bayes strategy with Jeffreys' prior.","PeriodicalId":325771,"journal":{"name":"2012 IEEE Information Theory Workshop","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124441779","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 : 2012-09-01DOI: 10.1109/ITW.2012.6404683
E. Akyol, Kumar Viswanatha, K. Rose
There are two common types of encoding paradigms in multiple descriptions (MD) coding: i) an approach based on conditional codebook generation, which was originally initiated by El-Gamal and Cover for the 2 channel setting and later extended to more than 2 channels by Venkataramani, Kramer and Goyal (VKG), ii) and an approach based on Slepian and Wolf's random binning technique, proposed by Pradhan, Puri and Ramchandran (PPR) for L >; 2 descriptions. It is well known that the achievable region due to PPR subsumes the VKG region for the symmetric Gaussian MD problem. Motivated by several practical advantages of random binning based methods over the conditional codebook encoding, this paper focuses on the following important questions: Does a random binning based scheme achieve the performance of conditional codebook encoding, even for the 2 descriptions scenario? Are random binning based approaches beneficial for settings that are not fully symmetric? This paper answers both these questions in the affirmative. Specifically, we propose a 2 descriptions coding scheme, based on random binning, which subsumes the currently known largest region for this problem due to Zhang and Berger. Moreover, we propose its extensions to L >; 2 channels and derive the associated achievable regions. The proposed scheme enjoys the advantages of both encoding paradigms making it particularly useful when there is symmetry only within a subset of the descriptions.
{"title":"On random binning versus conditional codebook methods in multiple descriptions coding","authors":"E. Akyol, Kumar Viswanatha, K. Rose","doi":"10.1109/ITW.2012.6404683","DOIUrl":"https://doi.org/10.1109/ITW.2012.6404683","url":null,"abstract":"There are two common types of encoding paradigms in multiple descriptions (MD) coding: i) an approach based on conditional codebook generation, which was originally initiated by El-Gamal and Cover for the 2 channel setting and later extended to more than 2 channels by Venkataramani, Kramer and Goyal (VKG), ii) and an approach based on Slepian and Wolf's random binning technique, proposed by Pradhan, Puri and Ramchandran (PPR) for L >; 2 descriptions. It is well known that the achievable region due to PPR subsumes the VKG region for the symmetric Gaussian MD problem. Motivated by several practical advantages of random binning based methods over the conditional codebook encoding, this paper focuses on the following important questions: Does a random binning based scheme achieve the performance of conditional codebook encoding, even for the 2 descriptions scenario? Are random binning based approaches beneficial for settings that are not fully symmetric? This paper answers both these questions in the affirmative. Specifically, we propose a 2 descriptions coding scheme, based on random binning, which subsumes the currently known largest region for this problem due to Zhang and Berger. Moreover, we propose its extensions to L >; 2 channels and derive the associated achievable regions. The proposed scheme enjoys the advantages of both encoding paradigms making it particularly useful when there is symmetry only within a subset of the descriptions.","PeriodicalId":325771,"journal":{"name":"2012 IEEE Information Theory Workshop","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123261516","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 : 2012-09-01DOI: 10.1109/ITW.2012.6404647
M. Sudan
The classical theory of communication, starting with the work of Shannon, has always that assumed the meaning of the messages being exchanged is known to the sender and receiver. This assumption set aside a tricky issue and allowed the theory to focus on the more pressing engineering problem of the time - namely communicating the bits efficiently and reliably. In the current times, we see increasing evidence that this question can no longer be set aside. On the one hand, communication of the bits have become very reliable, so reliability is no longer the pressing concern today. On the other hand, increasingly these bits are operated on by computers or mechanical devices. In such settings it becomes essential that the computers and machines know what the bits mean. In this article intended to accompany a talk to be given at the workshop, we describe some of our attempts to extract the notion of meaning, and the challenges this task poses. Meaning is best understood by focussing on the phenomenon of “misunderstanding”, i.e., when the receiver does not understand what the sender says. Misunderstanding, in turn, seems to emerge principally from “uncertainty”: Senders and receivers are uncertain about what the other knows/believes. We illustrate the problem in a simple setting, before moving on to describing our attempts to tackle the general complex task. Based on joint works with Brendan Juba (Harvard), Oded Goldreich (Weizmann), Adam Kalai (MSR New England), and Sanjeev Khanna (U. Penn.).
{"title":"Communication amid uncertainty","authors":"M. Sudan","doi":"10.1109/ITW.2012.6404647","DOIUrl":"https://doi.org/10.1109/ITW.2012.6404647","url":null,"abstract":"The classical theory of communication, starting with the work of Shannon, has always that assumed the meaning of the messages being exchanged is known to the sender and receiver. This assumption set aside a tricky issue and allowed the theory to focus on the more pressing engineering problem of the time - namely communicating the bits efficiently and reliably. In the current times, we see increasing evidence that this question can no longer be set aside. On the one hand, communication of the bits have become very reliable, so reliability is no longer the pressing concern today. On the other hand, increasingly these bits are operated on by computers or mechanical devices. In such settings it becomes essential that the computers and machines know what the bits mean. In this article intended to accompany a talk to be given at the workshop, we describe some of our attempts to extract the notion of meaning, and the challenges this task poses. Meaning is best understood by focussing on the phenomenon of “misunderstanding”, i.e., when the receiver does not understand what the sender says. Misunderstanding, in turn, seems to emerge principally from “uncertainty”: Senders and receivers are uncertain about what the other knows/believes. We illustrate the problem in a simple setting, before moving on to describing our attempts to tackle the general complex task. Based on joint works with Brendan Juba (Harvard), Oded Goldreich (Weizmann), Adam Kalai (MSR New England), and Sanjeev Khanna (U. Penn.).","PeriodicalId":325771,"journal":{"name":"2012 IEEE Information Theory Workshop","volume":"379 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126725286","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 : 2012-09-01DOI: 10.1109/ITW.2012.6404646
Mattias Andersson, A. Khisti, M. Skoglund
We study secret-key agreement over a non-coherent block-fading multiple input multiple output (MIMO) wiretap channel. We give an achievable scheme based on training and source emulation and analyze the rate in the high SNR regime. Based on this analysis we find the optimal number of antennas to use for training. Our main result is that if the sum of the number of antennas at Alice and Bob is larger than the coherence time of the channel, the achievable rate does not depend on the number of antennas at Eve. In this case source emulation is not needed, and using only training is optimal. We also consider the case when there is no public channel available. In this case we show that secret-key agreement is still possible by using the wireless channel for discussion, giving the same number of secure degrees of freedom as in the case with a public channel.
{"title":"Secret-key agreement over a non-coherent block-fading MIMO wiretap channel","authors":"Mattias Andersson, A. Khisti, M. Skoglund","doi":"10.1109/ITW.2012.6404646","DOIUrl":"https://doi.org/10.1109/ITW.2012.6404646","url":null,"abstract":"We study secret-key agreement over a non-coherent block-fading multiple input multiple output (MIMO) wiretap channel. We give an achievable scheme based on training and source emulation and analyze the rate in the high SNR regime. Based on this analysis we find the optimal number of antennas to use for training. Our main result is that if the sum of the number of antennas at Alice and Bob is larger than the coherence time of the channel, the achievable rate does not depend on the number of antennas at Eve. In this case source emulation is not needed, and using only training is optimal. We also consider the case when there is no public channel available. In this case we show that secret-key agreement is still possible by using the wireless channel for discussion, giving the same number of secure degrees of freedom as in the case with a public channel.","PeriodicalId":325771,"journal":{"name":"2012 IEEE Information Theory Workshop","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126847120","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 : 2012-09-01DOI: 10.1109/ITW.2012.6404637
Y. Kochman, A. Mazumdar, Yury Polyanskiy
This paper continues the investigation of the combinatorial formulation of the joint source-channel coding problem. In particular, the connections are drawn to error-reducing codes, isometric embeddings and list-decodable codes. The optimal performance for the repetition construction is derived and is shown to be achievable by low complexity Markov decoders. The compound variation of the problem is proposed and some initial results are put forward.
{"title":"Results on combinatorial joint source-channel coding","authors":"Y. Kochman, A. Mazumdar, Yury Polyanskiy","doi":"10.1109/ITW.2012.6404637","DOIUrl":"https://doi.org/10.1109/ITW.2012.6404637","url":null,"abstract":"This paper continues the investigation of the combinatorial formulation of the joint source-channel coding problem. In particular, the connections are drawn to error-reducing codes, isometric embeddings and list-decodable codes. The optimal performance for the repetition construction is derived and is shown to be achievable by low complexity Markov decoders. The compound variation of the problem is proposed and some initial results are put forward.","PeriodicalId":325771,"journal":{"name":"2012 IEEE Information Theory Workshop","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129598945","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 : 2012-09-01DOI: 10.1109/ITW.2012.6404771
Omur Ozel, E. Ekrem, S. Ulukus
We study the Gaussian wiretap channel with an energy harvesting transmitter which does not have a battery to save energy. In the absence of a battery, the necessary transmission energy is maintained by an i.i.d. energy arrival process. We observe that this channel is an instance of the state-dependent wiretap channel with state available only to the transmitter causally, where the state is the available energy at the transmitter. We prove that the entire capacity-equivocation region can be obtained by single-letter Shannon strategies and its boundary is achieved by input distributions with support set of Lebesgue measure zero.
{"title":"Gaussian wiretap channel with a batteryless energy harvesting transmitter","authors":"Omur Ozel, E. Ekrem, S. Ulukus","doi":"10.1109/ITW.2012.6404771","DOIUrl":"https://doi.org/10.1109/ITW.2012.6404771","url":null,"abstract":"We study the Gaussian wiretap channel with an energy harvesting transmitter which does not have a battery to save energy. In the absence of a battery, the necessary transmission energy is maintained by an i.i.d. energy arrival process. We observe that this channel is an instance of the state-dependent wiretap channel with state available only to the transmitter causally, where the state is the available energy at the transmitter. We prove that the entire capacity-equivocation region can be obtained by single-letter Shannon strategies and its boundary is achieved by input distributions with support set of Lebesgue measure zero.","PeriodicalId":325771,"journal":{"name":"2012 IEEE Information Theory Workshop","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128423969","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 : 2012-09-01DOI: 10.1109/ITW.2012.6404748
J. Muramatsu, S. Miyake
We investigate the problem of (independent) uniform random number generation and secret key agreement. A generator for the (independent) uniform random numbers is constructed by using a sparse matrix and it is applied to a secret key agreement protocol with strong secrecy. It is proved that the rate of the proposed codes can achieve the fundamental limits.
{"title":"Uniform random number generation by using sparse matrix","authors":"J. Muramatsu, S. Miyake","doi":"10.1109/ITW.2012.6404748","DOIUrl":"https://doi.org/10.1109/ITW.2012.6404748","url":null,"abstract":"We investigate the problem of (independent) uniform random number generation and secret key agreement. A generator for the (independent) uniform random numbers is constructed by using a sparse matrix and it is applied to a secret key agreement protocol with strong secrecy. It is proved that the rate of the proposed codes can achieve the fundamental limits.","PeriodicalId":325771,"journal":{"name":"2012 IEEE Information Theory Workshop","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114307501","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：