This paper reports some Braess-like paradoxes in peer-to-peer (P2P) trust management systems. We use the tools from game theory to model and analyze the reporting and exclusion processes and show how uncertainty and belief among peers might lead to surprising and unexpected peer behaviors, which, in turn, could make current P2P trust management systems ineffective. The contributions of the paper are the followings. First, we find that if a reputation system is not incentive-compatible, the more the number of peers in the system, the less likely that anyone will report about a malicious peer. Second, we address the issue of voting for exclusion of a (maliciously believed) peer and provide an analysis of the problem. By modeling the decision process as a Bayesian game, we find that the possible application of exclusion in P2P system might be dangerous. More precisely, our analysis shows that, under certain assumptions, the more the number of voting peers, the more likely that an innocent peer is excluded from the network. Finally, in the lights of the investigated paradoxes, we discuss possible solutions to improve the efficiency of current trust management systems in P2P networks.
{"title":"A Game-Theoretic Analysis of Trust Management in P2P Systems","authors":"Trinh Anh Tuan","doi":"10.1109/CCE.2006.350832","DOIUrl":"https://doi.org/10.1109/CCE.2006.350832","url":null,"abstract":"This paper reports some Braess-like paradoxes in peer-to-peer (P2P) trust management systems. We use the tools from game theory to model and analyze the reporting and exclusion processes and show how uncertainty and belief among peers might lead to surprising and unexpected peer behaviors, which, in turn, could make current P2P trust management systems ineffective. The contributions of the paper are the followings. First, we find that if a reputation system is not incentive-compatible, the more the number of peers in the system, the less likely that anyone will report about a malicious peer. Second, we address the issue of voting for exclusion of a (maliciously believed) peer and provide an analysis of the problem. By modeling the decision process as a Bayesian game, we find that the possible application of exclusion in P2P system might be dangerous. More precisely, our analysis shows that, under certain assumptions, the more the number of voting peers, the more likely that an innocent peer is excluded from the network. Finally, in the lights of the investigated paradoxes, we discuss possible solutions to improve the efficiency of current trust management systems in P2P networks.","PeriodicalId":148533,"journal":{"name":"2006 First International Conference on Communications and Electronics","volume":"124 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121534553","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}
Orthogonal frequency division multiple access (OFDMA) systems emerge as potential choices for the development of the next generation (4G) mobile communications system mainly due to their bandwidth efficiency and capability of inter symbol interference (ISI) combat. Recently, dynamic resource allocation (DRA) technique is intensively studied to enhance system performance such as throughput maximization, power minimization, fairness and so forth. However, the tradeoff between maximal throughput and fairness gets more attention since it adapts to varying wireless network conditions as well as provides reasonable fairness among users. In this paper, we focus on achieving the tradeoff in the downlink case. A comparison between several DRA schemes is given to illustrate how to get the tradeoff in a downlink OFDMA system.
{"title":"Schemes for Maximal Throughput and Fairness in Downlink OFDMA Systems","authors":"Tien-Dzung Nguyen, Youngnam Han","doi":"10.1109/CCE.2006.350828","DOIUrl":"https://doi.org/10.1109/CCE.2006.350828","url":null,"abstract":"Orthogonal frequency division multiple access (OFDMA) systems emerge as potential choices for the development of the next generation (4G) mobile communications system mainly due to their bandwidth efficiency and capability of inter symbol interference (ISI) combat. Recently, dynamic resource allocation (DRA) technique is intensively studied to enhance system performance such as throughput maximization, power minimization, fairness and so forth. However, the tradeoff between maximal throughput and fairness gets more attention since it adapts to varying wireless network conditions as well as provides reasonable fairness among users. In this paper, we focus on achieving the tradeoff in the downlink case. A comparison between several DRA schemes is given to illustrate how to get the tradeoff in a downlink OFDMA system.","PeriodicalId":148533,"journal":{"name":"2006 First International Conference on Communications and Electronics","volume":"207 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121864979","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}
The literature on pricing implicitly assumes an "infinite data" model, in which sources can sustain any data rate indefinitely. We assume a more realistic "finite data" model, in which sources occasionally run out of data; this leads to variable user data rates. Further, we assume that users have contracts with the service provider, specifying the rates at which they can inject traffic into the network. Our objective is to study how prices can be set such that a single link can be shared efficiently and fairly among users in a dynamically changing scenario where a subset of users occasionally has little data to send. User preferences are modelled by concave increasing utility functions. Further, we introduce two additional elements: a convex increasing disutility function and a convex increasing multiplicative congestion-penalty function. The disutility function takes the shortfall (contracted rate minus present rate) as its argument, and essentially encourages users to send traffic at their contracted rates, while the congestion-penalty function discourages heavy users from sending excess data when the link is congested. We obtain simple necessary and sufficient conditions on prices for fair and efficient link sharing; moreover, we show that a single price for all users achieves this. We illustrate the ideas using a simple experiment.
{"title":"Pricing a Shared Access Link for Fair and Efficient Operation with Variable User Data Rates","authors":"J. Kuri, S. Roy","doi":"10.1109/CCE.2006.350853","DOIUrl":"https://doi.org/10.1109/CCE.2006.350853","url":null,"abstract":"The literature on pricing implicitly assumes an \"infinite data\" model, in which sources can sustain any data rate indefinitely. We assume a more realistic \"finite data\" model, in which sources occasionally run out of data; this leads to variable user data rates. Further, we assume that users have contracts with the service provider, specifying the rates at which they can inject traffic into the network. Our objective is to study how prices can be set such that a single link can be shared efficiently and fairly among users in a dynamically changing scenario where a subset of users occasionally has little data to send. User preferences are modelled by concave increasing utility functions. Further, we introduce two additional elements: a convex increasing disutility function and a convex increasing multiplicative congestion-penalty function. The disutility function takes the shortfall (contracted rate minus present rate) as its argument, and essentially encourages users to send traffic at their contracted rates, while the congestion-penalty function discourages heavy users from sending excess data when the link is congested. We obtain simple necessary and sufficient conditions on prices for fair and efficient link sharing; moreover, we show that a single price for all users achieves this. We illustrate the ideas using a simple experiment.","PeriodicalId":148533,"journal":{"name":"2006 First International Conference on Communications and Electronics","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132509970","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}
In an H.264/AVC encoder, each macroblock can be coded in one of a large number of coding modes, which requires a huge computational effort. In this paper, we present a new method to speed up the mode decision process using RD cost prediction in addition to mode prediction. In general, video coding exploits spatial and temporal redundancies between video blocks, in particular temporal redundancy is a crucial key to compress a video sequence with little loss of image quality. The proposed method determines the best coding mode of a given macroblock by predicting the mode and its rate-distortion (RD) cost from neighboring MBs in time and space. Compared to the H.264/AVC reference software, the simulation results show that the proposed method can save about 60% of the number of RD cost computations resulting in up to 57% total encoding time reduction with up to 3.5% bit rate increase at the same PSNR.
{"title":"Fast Mode Decision for H.264/AVG using Mode and RD Cost Prediction","authors":"Ri Song-Hak, J. Ostermann","doi":"10.1109/CCE.2006.350815","DOIUrl":"https://doi.org/10.1109/CCE.2006.350815","url":null,"abstract":"In an H.264/AVC encoder, each macroblock can be coded in one of a large number of coding modes, which requires a huge computational effort. In this paper, we present a new method to speed up the mode decision process using RD cost prediction in addition to mode prediction. In general, video coding exploits spatial and temporal redundancies between video blocks, in particular temporal redundancy is a crucial key to compress a video sequence with little loss of image quality. The proposed method determines the best coding mode of a given macroblock by predicting the mode and its rate-distortion (RD) cost from neighboring MBs in time and space. Compared to the H.264/AVC reference software, the simulation results show that the proposed method can save about 60% of the number of RD cost computations resulting in up to 57% total encoding time reduction with up to 3.5% bit rate increase at the same PSNR.","PeriodicalId":148533,"journal":{"name":"2006 First International Conference on Communications and Electronics","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130029258","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}
In mobile ad hoc network (MANET), there are a number of routing schemes that have been proposed and several of these have been already extensively simulated or implemented as well. In this paper, we describe extension to routing algorithm based on location information to provide more efficient routing for mobile ad hoc networks. We propose replacing location-aided routing (LAR) with location-aided multipath routing (LAMR). We implemented LAMR through simulation using ns-2 and study its efficiency, and other properties. We use random waypoint mobility and compare LAMR approach versus ad hoc on-demand distant vector (AODV), ad hoc on-demand multipath distant vector (AOMDV) and LAR methods. Our simulation results demonstrate the performance benefits of LAMR over LAR and AODV in most movement scenarios. AOMDV does more frequent flooding of control packets and thus requires higher bandwidth usage than LAMR.
{"title":"Location-Aided Multipath Routing Method for Mobile Ad Hoc Wireless Networks","authors":"Ha Duyen Trung, W. Benjapolakul","doi":"10.1109/CCE.2006.350847","DOIUrl":"https://doi.org/10.1109/CCE.2006.350847","url":null,"abstract":"In mobile ad hoc network (MANET), there are a number of routing schemes that have been proposed and several of these have been already extensively simulated or implemented as well. In this paper, we describe extension to routing algorithm based on location information to provide more efficient routing for mobile ad hoc networks. We propose replacing location-aided routing (LAR) with location-aided multipath routing (LAMR). We implemented LAMR through simulation using ns-2 and study its efficiency, and other properties. We use random waypoint mobility and compare LAMR approach versus ad hoc on-demand distant vector (AODV), ad hoc on-demand multipath distant vector (AOMDV) and LAR methods. Our simulation results demonstrate the performance benefits of LAMR over LAR and AODV in most movement scenarios. AOMDV does more frequent flooding of control packets and thus requires higher bandwidth usage than LAMR.","PeriodicalId":148533,"journal":{"name":"2006 First International Conference on Communications and Electronics","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133729397","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 : 2006-10-01DOI: 10.1093/ietcom/e90-b.8.2006
Maduranga Liyanage, I. Sasase
In this paper, we propose an effective subcarrier allocation scheme for multiuser orthogonal frequency division multiple access (OFDMA) system in the downlink transmission with low computational complexity. In the proposed scheme, by taking multiple attributes of a user channel, such as carrier gain decrease rate and variation from the mean channel gain of the system, to determine a rank for the user, subcarriers are then allocated depending on the individual users' rank. Different channel characteristics are used to better understand a users' need to subcarriers and hence determine a priority to user. We also adopt an attribute weighing scheme to enhance the performance of the proposed scheme. The scheme is efficiently computational, by avoiding using iterations for the algorithm convergence and also common water-filling calculations which might become complex with increasing system parameters. Low complexity is achieved by allocating subcarriers to users depending on their determined rank. Our proposed scheme is simulated in comparison with other mathematically efficient subcarrier allocation schemes as well as with a conventional greedy allocation scheme. It is shown that proposed method demonstrates better results than the simulated schemes.
{"title":"Low Complexity Resource Allocation Algorithm by Multiple Attribute Weighing and User Ranking for OFDMA Systems","authors":"Maduranga Liyanage, I. Sasase","doi":"10.1093/ietcom/e90-b.8.2006","DOIUrl":"https://doi.org/10.1093/ietcom/e90-b.8.2006","url":null,"abstract":"In this paper, we propose an effective subcarrier allocation scheme for multiuser orthogonal frequency division multiple access (OFDMA) system in the downlink transmission with low computational complexity. In the proposed scheme, by taking multiple attributes of a user channel, such as carrier gain decrease rate and variation from the mean channel gain of the system, to determine a rank for the user, subcarriers are then allocated depending on the individual users' rank. Different channel characteristics are used to better understand a users' need to subcarriers and hence determine a priority to user. We also adopt an attribute weighing scheme to enhance the performance of the proposed scheme. The scheme is efficiently computational, by avoiding using iterations for the algorithm convergence and also common water-filling calculations which might become complex with increasing system parameters. Low complexity is achieved by allocating subcarriers to users depending on their determined rank. Our proposed scheme is simulated in comparison with other mathematically efficient subcarrier allocation schemes as well as with a conventional greedy allocation scheme. It is shown that proposed method demonstrates better results than the simulated schemes.","PeriodicalId":148533,"journal":{"name":"2006 First International Conference on Communications and Electronics","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114565800","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}
Applications of audio playback and communication often require the possibility to shape the signal spectra. This can easily be implemented in conjunction with audio coding techniques which are based on a spectral decomposition. Here, this can be accomplished by simply multiplying the decoded spectral components with different gain factors. However, since the transforms or filter banks used in coding produce a critically sampled representation, this can lead to undesirable non-compensated aliasing components in the resulting output signal. The gain factor dependent aliasing compensation technique presented in this paper reduces these effects in a very efficient way. The remaining aliasing components are almost as low as for the approximation of a non-critically sampled complex filter bank, while the new technique is of lower computational complexity and introduces less delay.
{"title":"Aliasing Reduction for Gain Control with Critically Sampled Filter Banks","authors":"B. Edler","doi":"10.1109/CCE.2006.350804","DOIUrl":"https://doi.org/10.1109/CCE.2006.350804","url":null,"abstract":"Applications of audio playback and communication often require the possibility to shape the signal spectra. This can easily be implemented in conjunction with audio coding techniques which are based on a spectral decomposition. Here, this can be accomplished by simply multiplying the decoded spectral components with different gain factors. However, since the transforms or filter banks used in coding produce a critically sampled representation, this can lead to undesirable non-compensated aliasing components in the resulting output signal. The gain factor dependent aliasing compensation technique presented in this paper reduces these effects in a very efficient way. The remaining aliasing components are almost as low as for the approximation of a non-critically sampled complex filter bank, while the new technique is of lower computational complexity and introduces less delay.","PeriodicalId":148533,"journal":{"name":"2006 First International Conference on Communications and Electronics","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125823526","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}
In most multitarget tracking approaches based on joint probabilistic data association (JPDA), it is difficult to apply the solutions to problems (due to the dimensionality curse of heavy complexity) where the number of targets varies dramatically. In this paper, we introduce an algorithm for detection of multitargets in wireless acoustic sensor networks (ADMAN); we localize detected targets by the particle filtering after the ADMAN. The purpose of ADMAN is detecting any number of targets (We know the approximate locations of targets during the detection algorithm.) in the field of interest. The advantage of ADMAN is its ability to cope with varying number of targets in time. ADMAN does not have any restrictions on the varying pattern of the target number.
{"title":"Algorithm for Detection and Localization of Multi-targets in Wireless Acoustic Sensor Networks","authors":"Jaechan Lim, Jinseok Lee, Sangjin Hong","doi":"10.1109/CCE.2006.350803","DOIUrl":"https://doi.org/10.1109/CCE.2006.350803","url":null,"abstract":"In most multitarget tracking approaches based on joint probabilistic data association (JPDA), it is difficult to apply the solutions to problems (due to the dimensionality curse of heavy complexity) where the number of targets varies dramatically. In this paper, we introduce an algorithm for detection of multitargets in wireless acoustic sensor networks (ADMAN); we localize detected targets by the particle filtering after the ADMAN. The purpose of ADMAN is detecting any number of targets (We know the approximate locations of targets during the detection algorithm.) in the field of interest. The advantage of ADMAN is its ability to cope with varying number of targets in time. ADMAN does not have any restrictions on the varying pattern of the target number.","PeriodicalId":148533,"journal":{"name":"2006 First International Conference on Communications and Electronics","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128684910","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}
Bui Viet Khoi, P. D. Tinh, Nguyen Nam Quan, I. Artudo, D. Manjarres, W. Heirman, C. Debaes, J. Dambre, J. V. Van Campenhout, H. Thienpont
The static interconnection network topologies in the distributed shared memory systems (DSM) have several limitations. The reconfigurable interconnection networks may reduce the network congestion, network latency and improve the overall performance. However it is necessary to know when the right moment to perform the reconfiguration is and how to implement it. In this paper, we present our study on communication patterns of parallel scientific and commercial benchmark applications on a simulated but realistic DSM machine and their relation to context switching in the operating system. We also propose a reconfiguration scheme that is triggered by the context switches.
{"title":"Reconfigurable interconnection networks in Distributed Shared Memory systems: a study on communication patterns","authors":"Bui Viet Khoi, P. D. Tinh, Nguyen Nam Quan, I. Artudo, D. Manjarres, W. Heirman, C. Debaes, J. Dambre, J. V. Van Campenhout, H. Thienpont","doi":"10.1109/CCE.2006.350798","DOIUrl":"https://doi.org/10.1109/CCE.2006.350798","url":null,"abstract":"The static interconnection network topologies in the distributed shared memory systems (DSM) have several limitations. The reconfigurable interconnection networks may reduce the network congestion, network latency and improve the overall performance. However it is necessary to know when the right moment to perform the reconfiguration is and how to implement it. In this paper, we present our study on communication patterns of parallel scientific and commercial benchmark applications on a simulated but realistic DSM machine and their relation to context switching in the operating system. We also propose a reconfiguration scheme that is triggered by the context switches.","PeriodicalId":148533,"journal":{"name":"2006 First International Conference on Communications and Electronics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130748615","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}
In this paper, the design problem of dynamic output feedback controller for asymptotic stabilization of uncertain neutral systems has been considered. A criterion for the existence of such controllers is derived based on linear matrix inequality (LMI) approach combined with the Lyapunov method. A parameterized characterization of the controllers is given in terms of the feasible solutions to the inequalities, which can be solved by various optimization algorithms. A numerical example is given to illustrate the proposed design method.
{"title":"Design of Dynamic Output-Feedback Controller for Stabilization of Uncertain Neutral Systems","authors":"J. Park","doi":"10.1109/CCE.2006.350794","DOIUrl":"https://doi.org/10.1109/CCE.2006.350794","url":null,"abstract":"In this paper, the design problem of dynamic output feedback controller for asymptotic stabilization of uncertain neutral systems has been considered. A criterion for the existence of such controllers is derived based on linear matrix inequality (LMI) approach combined with the Lyapunov method. A parameterized characterization of the controllers is given in terms of the feasible solutions to the inequalities, which can be solved by various optimization algorithms. A numerical example is given to illustrate the proposed design method.","PeriodicalId":148533,"journal":{"name":"2006 First International Conference on Communications and Electronics","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132947146","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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