Pub Date : 2008-08-15DOI: 10.1109/ITA.2008.4601020
S. K. Chilappagari, B. Vasic, M. Marcellin
A memory is a device in which information is stored at some time and retrieved at a later time . Let the information be stored in form of bits in registers (memory elements) each of which can store a single bit. The information storage capability of a memory is the number of information bits it stores. Building a memory with information storage capability of k bits with reliable memory elements requires k registers. Such a memory is termed as an irredundant memory. This paper considers the problem of building a memory with memory elements and logic gates which fail according to a known random mechanism. The required minimum redundancy memory in which makes arbitrarily reliable information possible is discussed. For a reliable storage, the information needs to be stored in coded form . To ensure reliability, a correcting circuit is employed which performs error correction and updates the contents of the registers with an estimate of the original codeword.
{"title":"Can the storage capacity of memories built from unreliable components be determined?","authors":"S. K. Chilappagari, B. Vasic, M. Marcellin","doi":"10.1109/ITA.2008.4601020","DOIUrl":"https://doi.org/10.1109/ITA.2008.4601020","url":null,"abstract":"A memory is a device in which information is stored at some time and retrieved at a later time . Let the information be stored in form of bits in registers (memory elements) each of which can store a single bit. The information storage capability of a memory is the number of information bits it stores. Building a memory with information storage capability of k bits with reliable memory elements requires k registers. Such a memory is termed as an irredundant memory. This paper considers the problem of building a memory with memory elements and logic gates which fail according to a known random mechanism. The required minimum redundancy memory in which makes arbitrarily reliable information possible is discussed. For a reliable storage, the information needs to be stored in coded form . To ensure reliability, a correcting circuit is employed which performs error correction and updates the contents of the registers with an estimate of the original codeword.","PeriodicalId":345196,"journal":{"name":"2008 Information Theory and Applications Workshop","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114370181","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 : 2008-08-15DOI: 10.1109/ITA.2008.4601016
I. Blake, T. Garefalakis
The number of times the trace of a certain function on an extension field assumes a fixed value in the base field is considered. It is shown that the set of all such values enjoys a Fourier transform like property with Kloosterman sums. The application of this property to coding and cryptography is briefly discussed.
{"title":"A note on Kloosterman sums and its application","authors":"I. Blake, T. Garefalakis","doi":"10.1109/ITA.2008.4601016","DOIUrl":"https://doi.org/10.1109/ITA.2008.4601016","url":null,"abstract":"The number of times the trace of a certain function on an extension field assumes a fixed value in the base field is considered. It is shown that the set of all such values enjoys a Fourier transform like property with Kloosterman sums. The application of this property to coding and cryptography is briefly discussed.","PeriodicalId":345196,"journal":{"name":"2008 Information Theory and Applications Workshop","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124739785","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 : 2008-08-15DOI: 10.1109/ITA.2008.4601041
Gaurav Sharma, S. Jaggi, B. Dey
In this work we show how existing network coding algorithms can be used to perform network tomography, i.e., estimate network topology. We first examine a simple variant of the popular distributed random network codes proposed by (Ho et al.) and show how it can enable each network node to passively estimate the network topology upstream of it at no cost to throughput. The delays introduced by each upstream node and link can also be similarly estimated. We then consider the scenario wherein an adversary hidden in the network wishes to disrupt the estimation of network topology. We show how network error-correcting codes can be used to reliably perform network tomography if the network has sufficient connectivity, and demonstrate that network tomography is impossible otherwise.
{"title":"Network tomography via network coding","authors":"Gaurav Sharma, S. Jaggi, B. Dey","doi":"10.1109/ITA.2008.4601041","DOIUrl":"https://doi.org/10.1109/ITA.2008.4601041","url":null,"abstract":"In this work we show how existing network coding algorithms can be used to perform network tomography, i.e., estimate network topology. We first examine a simple variant of the popular distributed random network codes proposed by (Ho et al.) and show how it can enable each network node to passively estimate the network topology upstream of it at no cost to throughput. The delays introduced by each upstream node and link can also be similarly estimated. We then consider the scenario wherein an adversary hidden in the network wishes to disrupt the estimation of network topology. We show how network error-correcting codes can be used to reliably perform network tomography if the network has sufficient connectivity, and demonstrate that network tomography is impossible otherwise.","PeriodicalId":345196,"journal":{"name":"2008 Information Theory and Applications Workshop","volume":"147 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115571535","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 : 2008-08-15DOI: 10.1109/ITA.2008.4601022
O. Dabeer
Consider a Gaussian multiple access channel (MAC) with two users, which do not always have a message to transmit. Neither user knows if the other is transmitting or not. Each user has two possible achievable rates depending on whether the other user is transmitting or not. Hence, in general, any coding scheme is characterized by a 4-tuple of rates. For given power constraints, we prove inner and outer bounds to the (4-dimensional) capacity region.
{"title":"On the single-slot capacity of random access over a Gaussian MAC","authors":"O. Dabeer","doi":"10.1109/ITA.2008.4601022","DOIUrl":"https://doi.org/10.1109/ITA.2008.4601022","url":null,"abstract":"Consider a Gaussian multiple access channel (MAC) with two users, which do not always have a message to transmit. Neither user knows if the other is transmitting or not. Each user has two possible achievable rates depending on whether the other user is transmitting or not. Hence, in general, any coding scheme is characterized by a 4-tuple of rates. For given power constraints, we prove inner and outer bounds to the (4-dimensional) capacity region.","PeriodicalId":345196,"journal":{"name":"2008 Information Theory and Applications Workshop","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125883704","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 : 2008-08-15DOI: 10.1109/ITA.2008.4601048
Aditya Mahajan, D. Teneketzis
A real-time communication system consisting of a first-order Markov source, a real-time encoder, a discrete memoryless channel, and a real-time decoder is considered. The quality of reconstruction is determined by a distortion function between the current source output and its reconstruction at the decoder. The distortion function does not accept delays. The objective is to choose encoding and decoding strategies to minimize the total expected distortion over a finite horizon. The problem is modelled as a decentralized stochastic control problem. A two step solution methodology is developed which provides a sequential decomposition of the problem and reduces exponentially the complexity to search for an optimal solution. The key step of our methodology is identifying information state sufficient for performance evaluation. The methodology can be extended to real-time communication problems with noisy feedback, feedback control problems with a noisy channel in the feedback loop, and decentralized diagnosis in logical discrete event systems.
{"title":"Optimal real-time encoder-decoding of Markov sources over noisy channels","authors":"Aditya Mahajan, D. Teneketzis","doi":"10.1109/ITA.2008.4601048","DOIUrl":"https://doi.org/10.1109/ITA.2008.4601048","url":null,"abstract":"A real-time communication system consisting of a first-order Markov source, a real-time encoder, a discrete memoryless channel, and a real-time decoder is considered. The quality of reconstruction is determined by a distortion function between the current source output and its reconstruction at the decoder. The distortion function does not accept delays. The objective is to choose encoding and decoding strategies to minimize the total expected distortion over a finite horizon. The problem is modelled as a decentralized stochastic control problem. A two step solution methodology is developed which provides a sequential decomposition of the problem and reduces exponentially the complexity to search for an optimal solution. The key step of our methodology is identifying information state sufficient for performance evaluation. The methodology can be extended to real-time communication problems with noisy feedback, feedback control problems with a noisy channel in the feedback loop, and decentralized diagnosis in logical discrete event systems.","PeriodicalId":345196,"journal":{"name":"2008 Information Theory and Applications Workshop","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130671401","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 : 2008-08-15DOI: 10.1109/ITA.2008.4601019
G. Caire, H. Shirani-Mehr
We consider a MIMO-OFDM broadcast channel and compare achievable ergodic rates under three channel state feedback schemes: analog feedback, direction quantized feedback and ldquotime-domainrdquo channel quantized feedback. The third scheme is new, and it is inspired by rate-distortion theory of Gaussian correlated sources. For each scheme we derive the conditions under which the system achieves full multiplexing gain. The first two schemes are direct extensions of previously proposed schemes to the OFDM case. The key difference with respect to the widely treated frequency-flat case is that in MIMO-OFDM the ldquofrequency-domainrdquo channel is a Gaussian correlated source. The new ldquotime-domainrdquo quantization scheme takes advantage of the channel frequency correlation structure and outperforms the other schemes. Furthermore, it is by far simpler to implement than complicated spherical vector quantization. In particular, we observe that no structured codebook design and vector quantization is actually needed for efficient channel state information feedback.
{"title":"Feedback schemes for multiuser MIMO-OFDM downlink","authors":"G. Caire, H. Shirani-Mehr","doi":"10.1109/ITA.2008.4601019","DOIUrl":"https://doi.org/10.1109/ITA.2008.4601019","url":null,"abstract":"We consider a MIMO-OFDM broadcast channel and compare achievable ergodic rates under three channel state feedback schemes: analog feedback, direction quantized feedback and ldquotime-domainrdquo channel quantized feedback. The third scheme is new, and it is inspired by rate-distortion theory of Gaussian correlated sources. For each scheme we derive the conditions under which the system achieves full multiplexing gain. The first two schemes are direct extensions of previously proposed schemes to the OFDM case. The key difference with respect to the widely treated frequency-flat case is that in MIMO-OFDM the ldquofrequency-domainrdquo channel is a Gaussian correlated source. The new ldquotime-domainrdquo quantization scheme takes advantage of the channel frequency correlation structure and outperforms the other schemes. Furthermore, it is by far simpler to implement than complicated spherical vector quantization. In particular, we observe that no structured codebook design and vector quantization is actually needed for efficient channel state information feedback.","PeriodicalId":345196,"journal":{"name":"2008 Information Theory and Applications Workshop","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114872208","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 : 2008-08-15DOI: 10.1109/ITA.2008.4601039
P. Ishwar, S. Pradhan
A relay-assisted distributed source coding problem with three statistically correlated sources is formulated and studied. Natural lower bounds for the rates are presented. The lower bounds are shown to be achievable for three special classes of joint source distributions. The achievable coding strategies for the three special classes are observed to have markedly different characteristics. A special class for which the lower bounds are not achievable is presented. A single unified coding strategy which subsumes all four special classes is derived.
{"title":"A relay-assisted distributed source coding problem","authors":"P. Ishwar, S. Pradhan","doi":"10.1109/ITA.2008.4601039","DOIUrl":"https://doi.org/10.1109/ITA.2008.4601039","url":null,"abstract":"A relay-assisted distributed source coding problem with three statistically correlated sources is formulated and studied. Natural lower bounds for the rates are presented. The lower bounds are shown to be achievable for three special classes of joint source distributions. The achievable coding strategies for the three special classes are observed to have markedly different characteristics. A special class for which the lower bounds are not achievable is presented. A single unified coding strategy which subsumes all four special classes is derived.","PeriodicalId":345196,"journal":{"name":"2008 Information Theory and Applications Workshop","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116380300","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 : 2008-08-15DOI: 10.1109/ITA.2008.4601072
G. Shamir
A pattern of a sequence is a sequence of integer indices with each index describing the order of first occurrence of the respective symbol in the original sequence. Several recent works studied entropy and entropy rate of patterns. Specifically, in a recent paper, tight general bounds on the block entropy of patterns of sequences generated by independent and identically distributed (i.i.d.) sources were derived. In this paper, precise approximations are given to the pattern block entropies for patterns of sequences generated by i.i.d. uniform and monotonic distributions, including distributions over the integers, and the geometric distribution. Numerical non-asymptotic bounds on the pattern block entropies of these distributions are provided even for very short blocks, and even for distributions that have infinite i.i.d. entropy rates. Conditional index entropy is also studied for distributions over smaller alphabets.
{"title":"Pattern entropy - revisited","authors":"G. Shamir","doi":"10.1109/ITA.2008.4601072","DOIUrl":"https://doi.org/10.1109/ITA.2008.4601072","url":null,"abstract":"A pattern of a sequence is a sequence of integer indices with each index describing the order of first occurrence of the respective symbol in the original sequence. Several recent works studied entropy and entropy rate of patterns. Specifically, in a recent paper, tight general bounds on the block entropy of patterns of sequences generated by independent and identically distributed (i.i.d.) sources were derived. In this paper, precise approximations are given to the pattern block entropies for patterns of sequences generated by i.i.d. uniform and monotonic distributions, including distributions over the integers, and the geometric distribution. Numerical non-asymptotic bounds on the pattern block entropies of these distributions are provided even for very short blocks, and even for distributions that have infinite i.i.d. entropy rates. Conditional index entropy is also studied for distributions over smaller alphabets.","PeriodicalId":345196,"journal":{"name":"2008 Information Theory and Applications Workshop","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127256078","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 : 2008-08-15DOI: 10.1109/ITA.2008.4601047
Upamanyu Madhow
The millimeter wave band from 60-95 GHz offers large swathes of unlicensed and semi-unlicensed spectrum, which may well form the basis for the next revolution in wireless communication, in which wireless catches up with wires.With the rapid scaling of silicon processes, low-cost implementations for radio frequency front-ends are on the horizon. A key challenge now is to parlay these breakthroughs into innovative system concepts. We review three such concepts here.Millimeter wave MIMO: The small carrier wavelength enables spatial multiplexing in line-of-sight environments, potentially resulting in point-to-point outdoor wireless links at optical speeds (40 Gbps) using bandwidths of the order of 5 GHz. Directional multihop networking: Indoor Gigabit wireless links based on 60 GHz unlicensed spectrum are subject to disruption due to line-of-sight blockage by obstacles such as furniture and humans. We show that a multihop architecture with a small number of relays assures full network connectivity. All-digital multiGigabit baseband: Since high-speed analog-to- digital conversion (ADC) is costly and power-hungry, in order to design all-digital baseband processing that can be implemented inexpensively by riding Moore's law, we must be able to perform signal processing with sloppy ADC. We discuss Shannon-theoretic limits and signal processing challenges in this context.
{"title":"MultiGigabit millimeter wave communication: System concepts and challenges","authors":"Upamanyu Madhow","doi":"10.1109/ITA.2008.4601047","DOIUrl":"https://doi.org/10.1109/ITA.2008.4601047","url":null,"abstract":"The millimeter wave band from 60-95 GHz offers large swathes of unlicensed and semi-unlicensed spectrum, which may well form the basis for the next revolution in wireless communication, in which wireless catches up with wires.With the rapid scaling of silicon processes, low-cost implementations for radio frequency front-ends are on the horizon. A key challenge now is to parlay these breakthroughs into innovative system concepts. We review three such concepts here.Millimeter wave MIMO: The small carrier wavelength enables spatial multiplexing in line-of-sight environments, potentially resulting in point-to-point outdoor wireless links at optical speeds (40 Gbps) using bandwidths of the order of 5 GHz. Directional multihop networking: Indoor Gigabit wireless links based on 60 GHz unlicensed spectrum are subject to disruption due to line-of-sight blockage by obstacles such as furniture and humans. We show that a multihop architecture with a small number of relays assures full network connectivity. All-digital multiGigabit baseband: Since high-speed analog-to- digital conversion (ADC) is costly and power-hungry, in order to design all-digital baseband processing that can be implemented inexpensively by riding Moore's law, we must be able to perform signal processing with sloppy ADC. We discuss Shannon-theoretic limits and signal processing challenges in this context.","PeriodicalId":345196,"journal":{"name":"2008 Information Theory and Applications Workshop","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125538519","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 : 2008-05-09DOI: 10.1109/ITA.2008.4601092
O. Somekh, O. Simeone, B. M. Zaidel, H. Poor, S. Shamai
The open problem of calculating the limiting spectrum (or its Shannon transform) of increasingly large random Hermitian finite-band matrices is described. In general, these matrices include a finite number of non-zero diagonals around their main diagonal regardless of their size. Two different communication setups which may be modeled using such matrices are presented: a simple cellular uplink channel, and a time varying inter-symbol interference channel. Selected recent information-theoretic works dealing directly with such channels are reviewed. Finally, several characteristics of the still unknown limiting spectrum of such matrices are listed, and some reflections are touched upon.
{"title":"On the spectrum of large random hermitian finite-band matrices","authors":"O. Somekh, O. Simeone, B. M. Zaidel, H. Poor, S. Shamai","doi":"10.1109/ITA.2008.4601092","DOIUrl":"https://doi.org/10.1109/ITA.2008.4601092","url":null,"abstract":"The open problem of calculating the limiting spectrum (or its Shannon transform) of increasingly large random Hermitian finite-band matrices is described. In general, these matrices include a finite number of non-zero diagonals around their main diagonal regardless of their size. Two different communication setups which may be modeled using such matrices are presented: a simple cellular uplink channel, and a time varying inter-symbol interference channel. Selected recent information-theoretic works dealing directly with such channels are reviewed. Finally, several characteristics of the still unknown limiting spectrum of such matrices are listed, and some reflections are touched upon.","PeriodicalId":345196,"journal":{"name":"2008 Information Theory and Applications Workshop","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133105978","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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