Pub Date : 2006-03-13DOI: 10.1109/ITW.2006.1633780
M. Chiang, S. Low, R. Calderbank, J. Doyle
Network protocols in layered architectures have historically been obtained primarily on an ad-hoc basis. Recent research has shown that network protocols may instead be holistically analyzed and systematically designed as distributed solutions to some global optimization problems in the form of Network Utility Maximization (NUM), providing insight into what they optimize and structures of the network protocol stack. This paper presents a short survey of the recent efforts towards a systematic understanding of 'layering' as 'optimization decomposition', where the overall communication network is modeled by a generalized NUM problem, each layer corresponds to a decomposed subproblem, and the interfaces among layers are quantified as functions of the optimization variables coordinating the sub-problems. Different decompositions lead to alternative layering architectures. We summarize several examples of horizontal decomposition into distributed computation and vertical decomposition into functional modules such as congestion control, routing, scheduling, random access, power control, and coding.
{"title":"Layering As Optimization Decomposition: Framework and Examples","authors":"M. Chiang, S. Low, R. Calderbank, J. Doyle","doi":"10.1109/ITW.2006.1633780","DOIUrl":"https://doi.org/10.1109/ITW.2006.1633780","url":null,"abstract":"Network protocols in layered architectures have historically been obtained primarily on an ad-hoc basis. Recent research has shown that network protocols may instead be holistically analyzed and systematically designed as distributed solutions to some global optimization problems in the form of Network Utility Maximization (NUM), providing insight into what they optimize and structures of the network protocol stack. This paper presents a short survey of the recent efforts towards a systematic understanding of 'layering' as 'optimization decomposition', where the overall communication network is modeled by a generalized NUM problem, each layer corresponds to a decomposed subproblem, and the interfaces among layers are quantified as functions of the optimization variables coordinating the sub-problems. Different decompositions lead to alternative layering architectures. We summarize several examples of horizontal decomposition into distributed computation and vertical decomposition into functional modules such as congestion control, routing, scheduling, random access, power control, and coding.","PeriodicalId":293144,"journal":{"name":"2006 IEEE Information Theory Workshop - ITW '06 Punta del Este","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128168199","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 : 2006-03-13DOI: 10.1109/ITW.2006.1633833
Jordi Diaz, O. Simeone, O. Somekh, Y. Bar-Ness
The sum-capacity of the multi-antenna Gaussian broadcast channel is known to be achieved by Dirty Paper Coding techniques, that require full channel state information at the base station. It has been recently shown that a sum-rate having the same scaling law of the sum-capacity with respect to the number of users n for a fixed signal to noise ratio (i.e., M log log n where M is the number of transmitting antennas) can be achieved by using reduced feedback (or equivalently reduced channel state information at the transmitter). In particular, it has been proved that n real and n integer numbers are enough to guarantee the optimal scaling law. In this paper, the optimal scaling law of the sum-rate is shown to be achievable with an even smaller amount of feedback and, more precisely, with 1) n log2(M + 1) bits, if a deterministic feedback scheme is employed; 2) an average number of feedback bits that scales as M log2M log n with the number of users n, if a selective (random) feedback scheme is employed.
{"title":"Scaling Law of the Sum-Rate for Multi-Antenna Broadcast Channels with Deterministic or Selective Binary Feedback","authors":"Jordi Diaz, O. Simeone, O. Somekh, Y. Bar-Ness","doi":"10.1109/ITW.2006.1633833","DOIUrl":"https://doi.org/10.1109/ITW.2006.1633833","url":null,"abstract":"The sum-capacity of the multi-antenna Gaussian broadcast channel is known to be achieved by Dirty Paper Coding techniques, that require full channel state information at the base station. It has been recently shown that a sum-rate having the same scaling law of the sum-capacity with respect to the number of users n for a fixed signal to noise ratio (i.e., M log log n where M is the number of transmitting antennas) can be achieved by using reduced feedback (or equivalently reduced channel state information at the transmitter). In particular, it has been proved that n real and n integer numbers are enough to guarantee the optimal scaling law. In this paper, the optimal scaling law of the sum-rate is shown to be achievable with an even smaller amount of feedback and, more precisely, with 1) n log2(M + 1) bits, if a deterministic feedback scheme is employed; 2) an average number of feedback bits that scales as M log2M log n with the number of users n, if a selective (random) feedback scheme is employed.","PeriodicalId":293144,"journal":{"name":"2006 IEEE Information Theory Workshop - ITW '06 Punta del Este","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115176716","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 : 2006-03-13DOI: 10.1109/ITW.2006.1633843
Lei Zhou, Shidong Zhou, Yan Yao
Multipath Rayleigh block fading channel with uniform energy spread in the low signal to noise ratio (SNR) regime is studied. Theoretical analysis shows that in the low SNR regime, the non-coherent mutual information is proportional to the channel coherence time and inversely proportional to the channel delay spread when the input signal is under the fourth moment constraint. Besides, due to the lack of the channel knowledge, the non-coherent mutual information degrades significantly to a value which is asymptotically quadratic in SNR while the frequency selectivity and the channel coherence contribute only linear terms to the non-coherent mutual information.
{"title":"Non-coherent Mutual Information of the Multipath Rayleigh Fading Channel in the Low SNR Regime","authors":"Lei Zhou, Shidong Zhou, Yan Yao","doi":"10.1109/ITW.2006.1633843","DOIUrl":"https://doi.org/10.1109/ITW.2006.1633843","url":null,"abstract":"Multipath Rayleigh block fading channel with uniform energy spread in the low signal to noise ratio (SNR) regime is studied. Theoretical analysis shows that in the low SNR regime, the non-coherent mutual information is proportional to the channel coherence time and inversely proportional to the channel delay spread when the input signal is under the fourth moment constraint. Besides, due to the lack of the channel knowledge, the non-coherent mutual information degrades significantly to a value which is asymptotically quadratic in SNR while the frequency selectivity and the channel coherence contribute only linear terms to the non-coherent mutual information.","PeriodicalId":293144,"journal":{"name":"2006 IEEE Information Theory Workshop - ITW '06 Punta del Este","volume":"113 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115374497","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 : 2006-03-13DOI: 10.1109/ITW.2006.1633788
A. Apostolico, Yongwook Choi
Lossy variants of the Ziv-Lempel family of encoders are built traditionally around the iterated quest for best matches within an assigned fidelity. Most of the resulting algorithms are inherently superlinear and not easy to implement and analyze. On the other hand, it is well known that any lossy scheme of low computational complexity must have the drawback that it cannot yield the minimal distortion which can be achieved by the optimal data compression algorithm specifically tailored for that case. This paper concentrates on parses of guaranteed low time performance, in which phrases are all distinct and generated mechanically by self-correlations of the source set forth by the parsing process. The goal of the paper is to describe the basic algorithm and some of its variants, show their good performance and latitude of practical applicability, and possibly stimulate in-depth analytical treatment, which is made particularly hard by the fact that the underlying processes are not stationary.
{"title":"Compressing with Collapsible Tries","authors":"A. Apostolico, Yongwook Choi","doi":"10.1109/ITW.2006.1633788","DOIUrl":"https://doi.org/10.1109/ITW.2006.1633788","url":null,"abstract":"Lossy variants of the Ziv-Lempel family of encoders are built traditionally around the iterated quest for best matches within an assigned fidelity. Most of the resulting algorithms are inherently superlinear and not easy to implement and analyze. On the other hand, it is well known that any lossy scheme of low computational complexity must have the drawback that it cannot yield the minimal distortion which can be achieved by the optimal data compression algorithm specifically tailored for that case. This paper concentrates on parses of guaranteed low time performance, in which phrases are all distinct and generated mechanically by self-correlations of the source set forth by the parsing process. The goal of the paper is to describe the basic algorithm and some of its variants, show their good performance and latitude of practical applicability, and possibly stimulate in-depth analytical treatment, which is made particularly hard by the fact that the underlying processes are not stationary.","PeriodicalId":293144,"journal":{"name":"2006 IEEE Information Theory Workshop - ITW '06 Punta del Este","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128790962","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 : 2006-03-13DOI: 10.1109/ITW.2006.1633782
M. Effros, T. Ho, Sukwon Kim
We describe a new tiling approach for network code design. The proposed method applies dynamic programming to find the best strategy among a restricted collection of network codes. We demonstrate the proposed strategy as a method for efficiently accommodating multiple unicasts in a wireless coding environment on a triangular lattice and discuss its generalization.
{"title":"A Tiling Approach to Network Code Design for Wireless Networks","authors":"M. Effros, T. Ho, Sukwon Kim","doi":"10.1109/ITW.2006.1633782","DOIUrl":"https://doi.org/10.1109/ITW.2006.1633782","url":null,"abstract":"We describe a new tiling approach for network code design. The proposed method applies dynamic programming to find the best strategy among a restricted collection of network codes. We demonstrate the proposed strategy as a method for efficiently accommodating multiple unicasts in a wireless coding environment on a triangular lattice and discuss its generalization.","PeriodicalId":293144,"journal":{"name":"2006 IEEE Information Theory Workshop - ITW '06 Punta del Este","volume":"92 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126345859","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 : 2006-03-13DOI: 10.1109/ITW.2006.1633801
E. Soljanin, N. Varnica, P. Whiting
Two incremental redundancy hybrid ARQ (IR-HARQ) schemes are compared: one is based on LDPC code ensembles with random transmission assignments, the other is based on recently introduced Raptor codes. A number of important issues, such as rate and power control, and error rate performance after each transmission on time varying binary-input, symmetric-output channels are addressed by analyzing performance of LDPC and Raptor codes on parallel channels. The theoretical results obtained for random code ensembles are tested on several practical code examples by simulation. Both theoretical and simulation results show that both LDPC and Raptor codes are suitable for HARQ schemes. Which codes would make a better choice depends mainly on the width of the signal-to-noise operating range of the HARQ scheme, prior knowledge of that range, and other design parameters and constraints dictated by standards.
{"title":"Punctured vs Rateless Codes for Hybrid ARQ","authors":"E. Soljanin, N. Varnica, P. Whiting","doi":"10.1109/ITW.2006.1633801","DOIUrl":"https://doi.org/10.1109/ITW.2006.1633801","url":null,"abstract":"Two incremental redundancy hybrid ARQ (IR-HARQ) schemes are compared: one is based on LDPC code ensembles with random transmission assignments, the other is based on recently introduced Raptor codes. A number of important issues, such as rate and power control, and error rate performance after each transmission on time varying binary-input, symmetric-output channels are addressed by analyzing performance of LDPC and Raptor codes on parallel channels. The theoretical results obtained for random code ensembles are tested on several practical code examples by simulation. Both theoretical and simulation results show that both LDPC and Raptor codes are suitable for HARQ schemes. Which codes would make a better choice depends mainly on the width of the signal-to-noise operating range of the HARQ scheme, prior knowledge of that range, and other design parameters and constraints dictated by standards.","PeriodicalId":293144,"journal":{"name":"2006 IEEE Information Theory Workshop - ITW '06 Punta del Este","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127494164","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 : 2006-03-13DOI: 10.1109/ITW.2006.1633825
E. Martinian, M. Wainwright
In this extended abstract, we provide a high-level overview of some of our recent work [10], [11], [9] on low-density graphical codes for various communication problems including lossy compression, binning, and coding with side information. Sparse graphical codes, particularly low-density parity check (LDPC) codes, are widely used and well understood in application to channel coding problems [16]. On the other hand, for other communication problems—especially those involving aspects of both channel and source coding—there remain various open questions associated with using low-density code constructions. Examples of such problems include (a) lossy source coding (data compression); (b) source coding with side information (the Wyner-Ziv problem [19]), and (c) channel coding with side information (the Gelfand-Pinsker problem [7]). Our work tackles these problems using sparse graphical constructions that are based on a combination of LDPC codes, and their dual versions, namely low-density generator matrix (LDGM) codes.
{"title":"Low-density constructions for lossy compression, binning, and coding with side information","authors":"E. Martinian, M. Wainwright","doi":"10.1109/ITW.2006.1633825","DOIUrl":"https://doi.org/10.1109/ITW.2006.1633825","url":null,"abstract":"In this extended abstract, we provide a high-level overview of some of our recent work [10], [11], [9] on low-density graphical codes for various communication problems including lossy compression, binning, and coding with side information. Sparse graphical codes, particularly low-density parity check (LDPC) codes, are widely used and well understood in application to channel coding problems [16]. On the other hand, for other communication problems—especially those involving aspects of both channel and source coding—there remain various open questions associated with using low-density code constructions. Examples of such problems include (a) lossy source coding (data compression); (b) source coding with side information (the Wyner-Ziv problem [19]), and (c) channel coding with side information (the Gelfand-Pinsker problem [7]). Our work tackles these problems using sparse graphical constructions that are based on a combination of LDPC codes, and their dual versions, namely low-density generator matrix (LDGM) codes.","PeriodicalId":293144,"journal":{"name":"2006 IEEE Information Theory Workshop - ITW '06 Punta del Este","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128120040","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 : 2006-03-13DOI: 10.1109/ITW.2006.1633837
Ryoji Ikegaya, K. Kasai, T. Shibuya, K. Sakaniwa
In this paper, we have derived the upper bound of the average block error probability of a given detailedly represented irregular low-density parity-check (LDPC) code ensemble under maximum likelihood decoding.
{"title":"The Block Error Probability of Detailedly Represented Irregular LDPC Code Ensembles under Maximum Likelihood Decoding","authors":"Ryoji Ikegaya, K. Kasai, T. Shibuya, K. Sakaniwa","doi":"10.1109/ITW.2006.1633837","DOIUrl":"https://doi.org/10.1109/ITW.2006.1633837","url":null,"abstract":"In this paper, we have derived the upper bound of the average block error probability of a given detailedly represented irregular low-density parity-check (LDPC) code ensemble under maximum likelihood decoding.","PeriodicalId":293144,"journal":{"name":"2006 IEEE Information Theory Workshop - ITW '06 Punta del Este","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132225339","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 : 2006-03-13DOI: 10.1109/ITW.2006.1633783
Kyomin Jung, D. Shah
Distributed computation of average is essential for many tasks such as estimation, eigenvalue computation, scheduling in the context of wireless sensor and ad-hoc networks. The wireless communication imposes the gossip constraint: each node can communicate with at most one other node at a given time. Recent interest in emerging wireless sensor network has led to exciting developments in the context of gossip algorithms for averaging. Most of the known algorithms are iterative and based on certain reversible random walk on the network graph. Subsequently, the running time of algorithm is affected by the diffusive nature of reversible random walk. For example, they take Ω(n2) time to compute average on a simple path or ring graph of n nodes. In contrast, an optimal (simple) centralized algorithm takes [unk](n) time to compute average in a path. This raises the following questions: is it possible for a distributed algorithm to compute average in O(n) time for path graph? is it possible to improve over diffusive behavior of current algorithms in arbitrary graphs? In this paper, we answer the above questions in affirmative. To overcome the diffusive nature of algorithms, we utilize non-reversible random walks. Specifically, we design our algorithms by "projecting down" the "lifted" non-reversible random walks of Diaconis-Holmes-Neal (2000) and Chen-Lovasz-Pak (1999). The running time of our algorithm is square-root of the time taken by corresponding reversible random walk for a large class of graphs including path.
{"title":"Fast Gossip via Non-reversible Random Walk","authors":"Kyomin Jung, D. Shah","doi":"10.1109/ITW.2006.1633783","DOIUrl":"https://doi.org/10.1109/ITW.2006.1633783","url":null,"abstract":"Distributed computation of average is essential for many tasks such as estimation, eigenvalue computation, scheduling in the context of wireless sensor and ad-hoc networks. The wireless communication imposes the gossip constraint: each node can communicate with at most one other node at a given time. Recent interest in emerging wireless sensor network has led to exciting developments in the context of gossip algorithms for averaging. Most of the known algorithms are iterative and based on certain reversible random walk on the network graph. Subsequently, the running time of algorithm is affected by the diffusive nature of reversible random walk. For example, they take Ω(n2) time to compute average on a simple path or ring graph of n nodes. In contrast, an optimal (simple) centralized algorithm takes [unk](n) time to compute average in a path. This raises the following questions: is it possible for a distributed algorithm to compute average in O(n) time for path graph? is it possible to improve over diffusive behavior of current algorithms in arbitrary graphs? In this paper, we answer the above questions in affirmative. To overcome the diffusive nature of algorithms, we utilize non-reversible random walks. Specifically, we design our algorithms by \"projecting down\" the \"lifted\" non-reversible random walks of Diaconis-Holmes-Neal (2000) and Chen-Lovasz-Pak (1999). The running time of our algorithm is square-root of the time taken by corresponding reversible random walk for a large class of graphs including path.","PeriodicalId":293144,"journal":{"name":"2006 IEEE Information Theory Workshop - ITW '06 Punta del Este","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129327275","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 : 2006-03-13DOI: 10.1109/ITW.2006.1633816
Hui Jin, R. Laroia, T. Richardson
We present a novel method for superposition coding applicable to OFDM systems in which the receivers being transmitted to are one high SNR receiver and one low SNR receiver. The degradation of the high SNR receiver, however, results primarily from channel uncertainty. Thus, we consider the effect of imperfect channel estimates, a ubiquitous problem in mobile wireless, and show that the new scheme performs much better than traditional schemes in such a setting.
{"title":"Superposition by Position","authors":"Hui Jin, R. Laroia, T. Richardson","doi":"10.1109/ITW.2006.1633816","DOIUrl":"https://doi.org/10.1109/ITW.2006.1633816","url":null,"abstract":"We present a novel method for superposition coding applicable to OFDM systems in which the receivers being transmitted to are one high SNR receiver and one low SNR receiver. The degradation of the high SNR receiver, however, results primarily from channel uncertainty. Thus, we consider the effect of imperfect channel estimates, a ubiquitous problem in mobile wireless, and show that the new scheme performs much better than traditional schemes in such a setting.","PeriodicalId":293144,"journal":{"name":"2006 IEEE Information Theory Workshop - ITW '06 Punta del Este","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122393818","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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