Pub Date : 2008-09-01DOI: 10.1109/ALLERTON.2008.4797665
Yuxing Han, Jiangtao Wen, J. Villasenor
We present a simple source coding algorithm for independent and identically distributed (i.i.d.) sources that gives coding efficiency performance close to that of arithmetic coding, but with much lower computational complexity and much higher robustness to mismatches between the assumed and actual symbol probabilities. The method is based on the principle that the probability of occurrence of a symbol sequence is determined by the total number of occurrences of each member of the symbol alphabet, but not by the order of occurrences. Thus, the coding of a string of symbols can be accomplished in three steps. First, the sequence length M is encoded using an exp-Golomb code. Second, the symbol occurrences frequencies are coded using exp-Golomb codes. Third, a set of fixed length codes are used to select among the equiprobable candidate sequences. In contrast with arithmetic coding, which involves significant computation during the process of encoding and decoding, in the method described here the actual encoding and decoding are extremely simple. Furthermore, the proposed algorithm is robust to mismatches between the assumed and actual symbol probabilities.
{"title":"Entropy coding using equiprobable partitioning","authors":"Yuxing Han, Jiangtao Wen, J. Villasenor","doi":"10.1109/ALLERTON.2008.4797665","DOIUrl":"https://doi.org/10.1109/ALLERTON.2008.4797665","url":null,"abstract":"We present a simple source coding algorithm for independent and identically distributed (i.i.d.) sources that gives coding efficiency performance close to that of arithmetic coding, but with much lower computational complexity and much higher robustness to mismatches between the assumed and actual symbol probabilities. The method is based on the principle that the probability of occurrence of a symbol sequence is determined by the total number of occurrences of each member of the symbol alphabet, but not by the order of occurrences. Thus, the coding of a string of symbols can be accomplished in three steps. First, the sequence length M is encoded using an exp-Golomb code. Second, the symbol occurrences frequencies are coded using exp-Golomb codes. Third, a set of fixed length codes are used to select among the equiprobable candidate sequences. In contrast with arithmetic coding, which involves significant computation during the process of encoding and decoding, in the method described here the actual encoding and decoding are extremely simple. Furthermore, the proposed algorithm is robust to mismatches between the assumed and actual symbol probabilities.","PeriodicalId":120561,"journal":{"name":"2008 46th Annual Allerton Conference on Communication, Control, and Computing","volume":"196 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134463862","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 : 2008-09-01DOI: 10.1109/ALLERTON.2008.4797635
P. Marbach, A. Eryilmaz
We propose and analyze a distributed backlog-based CSMA policy to achieve fairness and throughput-optimality in wireless multihop networks. The analysis is based on a CSMA fixed point approximation that is accurate for large networks with many small flows and a small sensing period.
{"title":"A backlog-based CSMA mechanism to achieve fairness and throughput-optimality in multihop wireless networks","authors":"P. Marbach, A. Eryilmaz","doi":"10.1109/ALLERTON.2008.4797635","DOIUrl":"https://doi.org/10.1109/ALLERTON.2008.4797635","url":null,"abstract":"We propose and analyze a distributed backlog-based CSMA policy to achieve fairness and throughput-optimality in wireless multihop networks. The analysis is based on a CSMA fixed point approximation that is accurate for large networks with many small flows and a small sensing period.","PeriodicalId":120561,"journal":{"name":"2008 46th Annual Allerton Conference on Communication, Control, and Computing","volume":"341 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134077115","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 : 2008-09-01DOI: 10.1109/ALLERTON.2008.4797569
M. Raginsky
This paper deals with information capacities of Gaussian channels under small (but nonvanishing) peak power constraints. We prove that, when the peak amplitude is below 1.05, the capacity of the scalar Gaussian channel is achieved by symmetric equiprobable signaling and is equal to at least 80% of the corresponding average-power capacity. The proof uses the identity of Guo, Shamai and Verdu that relates mutual information and minimum mean square error in Gaussian channels, together with several results on the minimax estimation of a bounded parameter in white Gaussian noise. We also give upper and lower bounds on peak-power capacities of vector Gaussian channels whose inputs are constrained to lie in suitably small ellipsoids and show that we can achieve at least 80% of the average-power capacity by having the transmitters use symmetric equiprobable signaling at amplitudes determined from the usual water-filling policy. The 80% figure comes from an upper bound on the ratio of the nonlinear and the linear minimax risks of estimating a bounded parameter in white Gaussian noise.
{"title":"On the information capacity of Gaussian channels under small peak power constraints","authors":"M. Raginsky","doi":"10.1109/ALLERTON.2008.4797569","DOIUrl":"https://doi.org/10.1109/ALLERTON.2008.4797569","url":null,"abstract":"This paper deals with information capacities of Gaussian channels under small (but nonvanishing) peak power constraints. We prove that, when the peak amplitude is below 1.05, the capacity of the scalar Gaussian channel is achieved by symmetric equiprobable signaling and is equal to at least 80% of the corresponding average-power capacity. The proof uses the identity of Guo, Shamai and Verdu that relates mutual information and minimum mean square error in Gaussian channels, together with several results on the minimax estimation of a bounded parameter in white Gaussian noise. We also give upper and lower bounds on peak-power capacities of vector Gaussian channels whose inputs are constrained to lie in suitably small ellipsoids and show that we can achieve at least 80% of the average-power capacity by having the transmitters use symmetric equiprobable signaling at amplitudes determined from the usual water-filling policy. The 80% figure comes from an upper bound on the ratio of the nonlinear and the linear minimax risks of estimating a bounded parameter in white Gaussian noise.","PeriodicalId":120561,"journal":{"name":"2008 46th Annual Allerton Conference on Communication, Control, and Computing","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117257313","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 : 2008-09-01DOI: 10.1109/ALLERTON.2008.4797566
L. Lai, Siu-Wai Ho, H. Poor
Biometric security systems are studied from an information theoretic perspective. A fundamental tradeoff between privacy, measured by the normalized equivocation rate of the biometric measurements, and security, measured by the rate of the key generated from the biometric measurements, is identified. The scenario in which a potential attacker does not have side information is considered first. The privacy-security region, which characterizes the above-noted tradeoff, is derived for this case. The close relationship between common information among random variables and the biometric security system is also revealed. The scenario in which the attacker has side information is then considered. Inner and outer bounds on the privacy-security region are derived in this case.
{"title":"Privacy-security tradeoffs in biometric security systems","authors":"L. Lai, Siu-Wai Ho, H. Poor","doi":"10.1109/ALLERTON.2008.4797566","DOIUrl":"https://doi.org/10.1109/ALLERTON.2008.4797566","url":null,"abstract":"Biometric security systems are studied from an information theoretic perspective. A fundamental tradeoff between privacy, measured by the normalized equivocation rate of the biometric measurements, and security, measured by the rate of the key generated from the biometric measurements, is identified. The scenario in which a potential attacker does not have side information is considered first. The privacy-security region, which characterizes the above-noted tradeoff, is derived for this case. The close relationship between common information among random variables and the biometric security system is also revealed. The scenario in which the attacker has side information is then considered. Inner and outer bounds on the privacy-security region are derived in this case.","PeriodicalId":120561,"journal":{"name":"2008 46th Annual Allerton Conference on Communication, Control, and Computing","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116244640","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 : 2008-09-01DOI: 10.1109/ALLERTON.2008.4797565
G. Theodorakopoulos, J. Baras, J. Le Boudec
A network user's decision to start and continue using security products is based on economic considerations. The cost of a security compromise (e.g., worm infection) is compared against the cost of deploying and maintaining a sufficient level of security. These costs are not necessarily the real ones, but rather the perceived costs, which depend on the amount of information available to a user at each time. Moreover, the costs (whether real or perceived) depend on the decisions of other users, too: The probability of a user getting infected depends on the security deployed by all the other users. In this paper, we combine an epidemic model for malware propagation in a network with a game theoretic model of the users' decisions to deploy security or not. Users can dynamically change their decision in order to maximize their currently perceived utility. We study the equilibrium points, and their dependence on the speed of the learning process through which the users learn the state of the network. We find that the faster the learning process, the higher the total network cost.
{"title":"Dynamic network security deployment under partial information","authors":"G. Theodorakopoulos, J. Baras, J. Le Boudec","doi":"10.1109/ALLERTON.2008.4797565","DOIUrl":"https://doi.org/10.1109/ALLERTON.2008.4797565","url":null,"abstract":"A network user's decision to start and continue using security products is based on economic considerations. The cost of a security compromise (e.g., worm infection) is compared against the cost of deploying and maintaining a sufficient level of security. These costs are not necessarily the real ones, but rather the perceived costs, which depend on the amount of information available to a user at each time. Moreover, the costs (whether real or perceived) depend on the decisions of other users, too: The probability of a user getting infected depends on the security deployed by all the other users. In this paper, we combine an epidemic model for malware propagation in a network with a game theoretic model of the users' decisions to deploy security or not. Users can dynamically change their decision in order to maximize their currently perceived utility. We study the equilibrium points, and their dependence on the speed of the learning process through which the users learn the state of the network. We find that the faster the learning process, the higher the total network cost.","PeriodicalId":120561,"journal":{"name":"2008 46th Annual Allerton Conference on Communication, Control, and Computing","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115131483","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 : 2008-09-01DOI: 10.1109/ALLERTON.2008.4797732
Aditya Mahajan, A. Nayyar, D. Teneketzis
Sequential decomposition of two general models of decentralized systems with non-classical information structures is presented. In model A, all agents have two observations at each step: a common observation that all agents observe and a private observation of their own. The control actions of each agent is based on all past common observations, the current private observation and the contents of its memory. At each step, each agent also updates the contents of its memory. A cost function, which depends on the state of the plant and the control actions of all agents, is given. The objective is to choose control and memory update functions for all agents to either minimize a total expected cost over a finite horizon or to minimize a discounted cost over an infinite horizon. In model B, the agents do not have any common observation, the rest is same as in model A. The key idea of our solution methodology is the following. From the point of view of a fictitious agent that observes all common observations, the system can be viewed as a centralized system with partial observations. This allows us to identify information states and obtain a sequential decomposition. When the system variables take values in finite sets, the optimality equations of the sequential decomposition are similar to those of partially observable Markov decision processes (POMDP) with finite state and action spaces. For such systems, we can use algorithms for POMDPs to compute optimal designs for models A and B.
{"title":"Identifying tractable decentralized control problems on the basis of information structure","authors":"Aditya Mahajan, A. Nayyar, D. Teneketzis","doi":"10.1109/ALLERTON.2008.4797732","DOIUrl":"https://doi.org/10.1109/ALLERTON.2008.4797732","url":null,"abstract":"Sequential decomposition of two general models of decentralized systems with non-classical information structures is presented. In model A, all agents have two observations at each step: a common observation that all agents observe and a private observation of their own. The control actions of each agent is based on all past common observations, the current private observation and the contents of its memory. At each step, each agent also updates the contents of its memory. A cost function, which depends on the state of the plant and the control actions of all agents, is given. The objective is to choose control and memory update functions for all agents to either minimize a total expected cost over a finite horizon or to minimize a discounted cost over an infinite horizon. In model B, the agents do not have any common observation, the rest is same as in model A. The key idea of our solution methodology is the following. From the point of view of a fictitious agent that observes all common observations, the system can be viewed as a centralized system with partial observations. This allows us to identify information states and obtain a sequential decomposition. When the system variables take values in finite sets, the optimality equations of the sequential decomposition are similar to those of partially observable Markov decision processes (POMDP) with finite state and action spaces. For such systems, we can use algorithms for POMDPs to compute optimal designs for models A and B.","PeriodicalId":120561,"journal":{"name":"2008 46th Annual Allerton Conference on Communication, Control, and Computing","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115295093","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 : 2008-09-01DOI: 10.1109/ALLERTON.2008.4797531
S. Pawar, A. Avestimehr, David Tse
We show that the diversity-multiplexing tradeoff of a half-duplex single-relay channel with identically distributed Rayleigh fading channel gains meets the 2 by 1 MISO bound. We generalize the result to the case when there are N non-interfering relays and show that the diversity-multiplexing tradeoff is equal to the N + 1 by 1 MISO bound.
{"title":"Diversity-multiplexing tradeoff of the half-duplex relay channel","authors":"S. Pawar, A. Avestimehr, David Tse","doi":"10.1109/ALLERTON.2008.4797531","DOIUrl":"https://doi.org/10.1109/ALLERTON.2008.4797531","url":null,"abstract":"We show that the diversity-multiplexing tradeoff of a half-duplex single-relay channel with identically distributed Rayleigh fading channel gains meets the 2 by 1 MISO bound. We generalize the result to the case when there are N non-interfering relays and show that the diversity-multiplexing tradeoff is equal to the N + 1 by 1 MISO bound.","PeriodicalId":120561,"journal":{"name":"2008 46th Annual Allerton Conference on Communication, Control, and Computing","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115456488","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 : 2008-09-01DOI: 10.1109/ALLERTON.2008.4797673
Changho Suh, David Tse
In this paper, we propose a new way of interference management for cellular networks. We develop the scheme that approaches to interference-free degree-of-freedom (dof) as the number K of users in each cell increases. Also we find the corresponding bandwidth scaling conditions for typical wireless channels: multi-path channels and single-path channels with propagation delay. The scheme is based on interference alignment. Especially for more-than-two-cell cases where there are multiple non-intended BSs, we propose a new version of interference alignment, namely subspace interference alignment. The idea is to align interferences into multi-dimensional subspace (instead of one dimension) for simultaneous alignments at multiple non-intended BSs. The proposed scheme requires finite dimensions growing linearly with K, i.e., ~O(K).
{"title":"Interference Alignment for Cellular Networks","authors":"Changho Suh, David Tse","doi":"10.1109/ALLERTON.2008.4797673","DOIUrl":"https://doi.org/10.1109/ALLERTON.2008.4797673","url":null,"abstract":"In this paper, we propose a new way of interference management for cellular networks. We develop the scheme that approaches to interference-free degree-of-freedom (dof) as the number K of users in each cell increases. Also we find the corresponding bandwidth scaling conditions for typical wireless channels: multi-path channels and single-path channels with propagation delay. The scheme is based on interference alignment. Especially for more-than-two-cell cases where there are multiple non-intended BSs, we propose a new version of interference alignment, namely subspace interference alignment. The idea is to align interferences into multi-dimensional subspace (instead of one dimension) for simultaneous alignments at multiple non-intended BSs. The proposed scheme requires finite dimensions growing linearly with K, i.e., ~O(K).","PeriodicalId":120561,"journal":{"name":"2008 46th Annual Allerton Conference on Communication, Control, and Computing","volume":"88 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124738666","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 : 2008-09-01DOI: 10.1109/ALLERTON.2008.4797583
S. Sanghavi, D. Malioutov, A. Willsky
This paper investigates the performance of belief propagation (BP) as a distributed solution to two combinatorial resource allocation problems arising in sensor networks: network formation and fusion center location. We model these problems by max-weight b-matching and uncapacitated facility location, respectively. Each of these is a classical optimization problem. For both problems, we (a) show how BP can be simplified for implementation in distributed environments where transmissions are broadcast and can interfere, (b) derive a principled interpretation of estimates before convergence, and (c) compare the performance of BP to that of linear programming.
{"title":"Networking sensors using belief propagation","authors":"S. Sanghavi, D. Malioutov, A. Willsky","doi":"10.1109/ALLERTON.2008.4797583","DOIUrl":"https://doi.org/10.1109/ALLERTON.2008.4797583","url":null,"abstract":"This paper investigates the performance of belief propagation (BP) as a distributed solution to two combinatorial resource allocation problems arising in sensor networks: network formation and fusion center location. We model these problems by max-weight b-matching and uncapacitated facility location, respectively. Each of these is a classical optimization problem. For both problems, we (a) show how BP can be simplified for implementation in distributed environments where transmissions are broadcast and can interfere, (b) derive a principled interpretation of estimates before convergence, and (c) compare the performance of BP to that of linear programming.","PeriodicalId":120561,"journal":{"name":"2008 46th Annual Allerton Conference on Communication, Control, and Computing","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123518513","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 : 2008-09-01DOI: 10.1109/ALLERTON.2008.4797572
Jun Zhang, J. Andrews, R. Heath
This paper considers fundamental limits on adaptive multiple-input multiple-output (MIMO) transmission with imperfect channel state information at the transmitter (CSIT). First, the achievable ergodic rates are derived for both single-user and multi-user MIMO systems with different CSIT assumptions, which shows that single-user MIMO is robust to imperfect CSIT while multiuser MIMO loses spatial multiplexing gain in proportion to delay and inverse with channel quantization codebook size. A single-user/multiuser mode switching rule is then proposed based on the average SNR, the amount of delay, and the quantization codebook size. The operating regions for single-user and multiuser modes are determined, which can be used to select the preferred mode. It is shown that the multiuser mode should not be activated when the delay is large or the codebook size is small.
{"title":"Single-user MIMO vs. Multiuser MIMO in the broadcast channel with CSIT constraints","authors":"Jun Zhang, J. Andrews, R. Heath","doi":"10.1109/ALLERTON.2008.4797572","DOIUrl":"https://doi.org/10.1109/ALLERTON.2008.4797572","url":null,"abstract":"This paper considers fundamental limits on adaptive multiple-input multiple-output (MIMO) transmission with imperfect channel state information at the transmitter (CSIT). First, the achievable ergodic rates are derived for both single-user and multi-user MIMO systems with different CSIT assumptions, which shows that single-user MIMO is robust to imperfect CSIT while multiuser MIMO loses spatial multiplexing gain in proportion to delay and inverse with channel quantization codebook size. A single-user/multiuser mode switching rule is then proposed based on the average SNR, the amount of delay, and the quantization codebook size. The operating regions for single-user and multiuser modes are determined, which can be used to select the preferred mode. It is shown that the multiuser mode should not be activated when the delay is large or the codebook size is small.","PeriodicalId":120561,"journal":{"name":"2008 46th Annual Allerton Conference on Communication, Control, and Computing","volume":"7 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123686047","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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