Pub Date : 2017-06-01DOI: 10.1109/CWIT.2017.7994825
M. Ammari, P. Fortier
A multiple-input multiple-output (MIMO) wiretap channel in the presence of one multiple-antenna eavesdropper is considered. We assume that imperfect channel state information (CSI) on the legitimate link and only statistical CSI of the eavesdropper channel are available at the transmitter. This paper addresses the issue of optimal input covariance matrix design that maximizes the secrecy rate subject to the total power constraint. The secrecy rate maximization (SRM) is studied under a relaxed assumption on the perfect CSI.We reformulate the SRM problem and propose an alternating optimization (AO) algorithm to find the optimal input covariance matrix. Simulation results are presented to validate the effectiveness of the proposed approach. The impact of the channel estimation error is investigated.
{"title":"Secrecy rate maximization for MIMO wiretap channels with channel uncertainty","authors":"M. Ammari, P. Fortier","doi":"10.1109/CWIT.2017.7994825","DOIUrl":"https://doi.org/10.1109/CWIT.2017.7994825","url":null,"abstract":"A multiple-input multiple-output (MIMO) wiretap channel in the presence of one multiple-antenna eavesdropper is considered. We assume that imperfect channel state information (CSI) on the legitimate link and only statistical CSI of the eavesdropper channel are available at the transmitter. This paper addresses the issue of optimal input covariance matrix design that maximizes the secrecy rate subject to the total power constraint. The secrecy rate maximization (SRM) is studied under a relaxed assumption on the perfect CSI.We reformulate the SRM problem and propose an alternating optimization (AO) algorithm to find the optimal input covariance matrix. Simulation results are presented to validate the effectiveness of the proposed approach. The impact of the channel estimation error is investigated.","PeriodicalId":247812,"journal":{"name":"2017 15th Canadian Workshop on Information Theory (CWIT)","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130069152","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 : 2017-06-01DOI: 10.1109/CWIT.2017.7994835
Mohammad Kazem Izadinasab, M. O. Damen, H. Najafi
Two near-optimal, low-complexity latticereduction- aided (LRA) conditional detectors are proposed for multiple-input multiple-output (MIMO) systems. The reduction is performed only on a selection of columns of the channel matrix and conditional optimization is performed on the remaining ones. In the proposed schemes, the best submatrix for conditional detection is selected by considering all possible submatrices and choosing the one that gives the best metric. For quasi-static channels, where the cost of lattice reduction can be negligible over the whole packet over which the channel is constant, the complexity of the proposed schemes is only linear in the size of the QAM modulation used. The near-optimal error performances of the proposed schemes are verified by analysis and simulations.
{"title":"Efficient lattice-reduction-aided conditional detection for MIMO systems","authors":"Mohammad Kazem Izadinasab, M. O. Damen, H. Najafi","doi":"10.1109/CWIT.2017.7994835","DOIUrl":"https://doi.org/10.1109/CWIT.2017.7994835","url":null,"abstract":"Two near-optimal, low-complexity latticereduction- aided (LRA) conditional detectors are proposed for multiple-input multiple-output (MIMO) systems. The reduction is performed only on a selection of columns of the channel matrix and conditional optimization is performed on the remaining ones. In the proposed schemes, the best submatrix for conditional detection is selected by considering all possible submatrices and choosing the one that gives the best metric. For quasi-static channels, where the cost of lattice reduction can be negligible over the whole packet over which the channel is constant, the complexity of the proposed schemes is only linear in the size of the QAM modulation used. The near-optimal error performances of the proposed schemes are verified by analysis and simulations.","PeriodicalId":247812,"journal":{"name":"2017 15th Canadian Workshop on Information Theory (CWIT)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129165692","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 : 2017-06-01DOI: 10.1109/CWIT.2017.7994812
H. Al-Lawati, Nuwan S. Ferdinand, S. Draper
Coded caching has gained a lot of interest recently. It jointly optimizes placement and delivery phases to create network-coded multicast opportunities to attain performance that surpasses conventional uncoded caching schemes. To the best of our knowledge, all coded caching systems studied in the literature are based on content popularity distributions as seen from the server's point of view. In this paper, we present a different approach to deal with coded caching problem. In particular, we analyze coded caching systems when each user's preferences are known to the system. Numerical results show that our approach outperforms the existing methods in certain regimes.
{"title":"Coded caching with non-identical user demands","authors":"H. Al-Lawati, Nuwan S. Ferdinand, S. Draper","doi":"10.1109/CWIT.2017.7994812","DOIUrl":"https://doi.org/10.1109/CWIT.2017.7994812","url":null,"abstract":"Coded caching has gained a lot of interest recently. It jointly optimizes placement and delivery phases to create network-coded multicast opportunities to attain performance that surpasses conventional uncoded caching schemes. To the best of our knowledge, all coded caching systems studied in the literature are based on content popularity distributions as seen from the server's point of view. In this paper, we present a different approach to deal with coded caching problem. In particular, we analyze coded caching systems when each user's preferences are known to the system. Numerical results show that our approach outperforms the existing methods in certain regimes.","PeriodicalId":247812,"journal":{"name":"2017 15th Canadian Workshop on Information Theory (CWIT)","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131423811","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 : 2017-06-01DOI: 10.1109/CWIT.2017.7994815
Bingcheng Zhu, Julian Cheng, Jun Yan, Jinyuan Wang, Lenan Wu, Yongjin Wang
Existing asymptotic analysis techniques fail to provide closed-form asymptotic outage probability expressions for lognormal fading channels due to the fact that lognormal fading channel distributions have an infinite diversity order. In this work, we develop a new analytical technique to study the asymptotic outage probability of maximum-ratio combining and equalgain combining over independent lognormal fading channels. The derived closed-form asymptotic expressions, which can be expressed in terms of the well-known Marcum-Q function, are accurate in high signal-to-noise ratio (SNR) regimes. The results reveal insights into the long-standing problem of asymptotic analyses for diversity systems over lognormal fading channels, and can help circumvent the time-consuming Monte Carlo simulation and numerical integration in large SNR region.
{"title":"A new technique for analyzing asymptotic outage performance of diversity over lognormal fading channels","authors":"Bingcheng Zhu, Julian Cheng, Jun Yan, Jinyuan Wang, Lenan Wu, Yongjin Wang","doi":"10.1109/CWIT.2017.7994815","DOIUrl":"https://doi.org/10.1109/CWIT.2017.7994815","url":null,"abstract":"Existing asymptotic analysis techniques fail to provide closed-form asymptotic outage probability expressions for lognormal fading channels due to the fact that lognormal fading channel distributions have an infinite diversity order. In this work, we develop a new analytical technique to study the asymptotic outage probability of maximum-ratio combining and equalgain combining over independent lognormal fading channels. The derived closed-form asymptotic expressions, which can be expressed in terms of the well-known Marcum-Q function, are accurate in high signal-to-noise ratio (SNR) regimes. The results reveal insights into the long-standing problem of asymptotic analyses for diversity systems over lognormal fading channels, and can help circumvent the time-consuming Monte Carlo simulation and numerical integration in large SNR region.","PeriodicalId":247812,"journal":{"name":"2017 15th Canadian Workshop on Information Theory (CWIT)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128502021","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 : 2017-06-01DOI: 10.1109/CWIT.2017.7994823
A. Amirzadeh, M. H. Taieb, J. Chouinard
This paper proposes a physical layer coding scheme to provide reliability and security in wireless communication systems. An Adaptive Granular Hybrid Automatic Repeat re- Quest (AG-HARQ) scheme based on Low-Density-Parity-Check (LDPC) codes is proposed. In the AG-HARQ protocol, the whole codewords are first transmitted (by Alice) to the intended receiver (Bob) and potentially intercepted by an unauthorized receiver or eavesdropper (Eve). Whenever the legitimate receiver (Bob) fails to decode the correct message, the received codewords are splitted into sub-packets and Bob computes a decoding confidence index for each of these sub-packets. Bob can then request a retransmission of those sub-packets having the lowest confidence indexes. These sub-packets are requested by Bob until correct decoding or until a maximum number of retransmissions is reached. An error contamination (EC) mechanism is also proposed which spreads the errors in the current frame with a scrambler and to the other frames by use of block interleavers. The proposed scheme ensures reliable and secure communication even in the case of negative Security Gap (SG) where the eavesdropper's channel benefits from better channel conditions than the legitimate channel.
{"title":"Physical layer secrecy for wireless communication systems using adaptive HARQ with error contamination","authors":"A. Amirzadeh, M. H. Taieb, J. Chouinard","doi":"10.1109/CWIT.2017.7994823","DOIUrl":"https://doi.org/10.1109/CWIT.2017.7994823","url":null,"abstract":"This paper proposes a physical layer coding scheme to provide reliability and security in wireless communication systems. An Adaptive Granular Hybrid Automatic Repeat re- Quest (AG-HARQ) scheme based on Low-Density-Parity-Check (LDPC) codes is proposed. In the AG-HARQ protocol, the whole codewords are first transmitted (by Alice) to the intended receiver (Bob) and potentially intercepted by an unauthorized receiver or eavesdropper (Eve). Whenever the legitimate receiver (Bob) fails to decode the correct message, the received codewords are splitted into sub-packets and Bob computes a decoding confidence index for each of these sub-packets. Bob can then request a retransmission of those sub-packets having the lowest confidence indexes. These sub-packets are requested by Bob until correct decoding or until a maximum number of retransmissions is reached. An error contamination (EC) mechanism is also proposed which spreads the errors in the current frame with a scrambler and to the other frames by use of block interleavers. The proposed scheme ensures reliable and secure communication even in the case of negative Security Gap (SG) where the eavesdropper's channel benefits from better channel conditions than the legitimate channel.","PeriodicalId":247812,"journal":{"name":"2017 15th Canadian Workshop on Information Theory (CWIT)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132982094","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 : 2017-02-08DOI: 10.1109/CWIT.2017.7994819
Mehrtash Mehrabi, M. Ardakani
Distributed and cloud storage systems are used to reliably store large-scale data. To enhance data reliability, erasure codes have been recently proposed and used in real-world distributed and cloud storage systems. Conventional erasure codes are not suitable for distributed storage systems, as they cause significant repair bandwidth and disk I/O. As a solution, a class of erasure codes called locally repairable codes (LRCs) have been proposed, where repairing failed nodes requires access to a small number of available nodes, hence reducing the repair bandwidth and disk I/O. Because of their practical importance, LRCs and in particular their achievable minimum distance have been the topic of many recent studies. In this paper, we find an achievable bound on the minimum distance of a class of LRCs. Furthermore, we show how to construct codes that achieve our proposed bound and compare our results with the existing bounds in the literature.
{"title":"On minimum distance of locally repairable codes","authors":"Mehrtash Mehrabi, M. Ardakani","doi":"10.1109/CWIT.2017.7994819","DOIUrl":"https://doi.org/10.1109/CWIT.2017.7994819","url":null,"abstract":"Distributed and cloud storage systems are used to reliably store large-scale data. To enhance data reliability, erasure codes have been recently proposed and used in real-world distributed and cloud storage systems. Conventional erasure codes are not suitable for distributed storage systems, as they cause significant repair bandwidth and disk I/O. As a solution, a class of erasure codes called locally repairable codes (LRCs) have been proposed, where repairing failed nodes requires access to a small number of available nodes, hence reducing the repair bandwidth and disk I/O. Because of their practical importance, LRCs and in particular their achievable minimum distance have been the topic of many recent studies. In this paper, we find an achievable bound on the minimum distance of a class of LRCs. Furthermore, we show how to construct codes that achieve our proposed bound and compare our results with the existing bounds in the literature.","PeriodicalId":247812,"journal":{"name":"2017 15th Canadian Workshop on Information Theory (CWIT)","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126448034","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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