Pub Date : 2009-11-30DOI: 10.1109/GLOCOM.2009.5426312
Harald Ø verby
Optical Packet/Burst Switching (OPS/OBS) has emerged as a promising candidate for the next-generation all-optical network scenario. A crucial issue in OPS/OBS networks is how to provide packet loss rate (PLR) differentiation at the network layer. In this paper we propose a novel PLR differentiation scheme that utilizes network layer packet redundancy in order to isolate service classes in an OPS/OBS network. We derive an analytical model of the proposed scheme based on reduced load Erlang fix-point analysis. A numerical evaluation shows that the isolation degree between the service classes is dependent on the amount of redundancy, system load and share of high priority traffic.
{"title":"Packet Loss Differentiation Using Network Layer Packet Redundancy in Optical Packet/Burst Switched Networks","authors":"Harald Ø verby","doi":"10.1109/GLOCOM.2009.5426312","DOIUrl":"https://doi.org/10.1109/GLOCOM.2009.5426312","url":null,"abstract":"Optical Packet/Burst Switching (OPS/OBS) has emerged as a promising candidate for the next-generation all-optical network scenario. A crucial issue in OPS/OBS networks is how to provide packet loss rate (PLR) differentiation at the network layer. In this paper we propose a novel PLR differentiation scheme that utilizes network layer packet redundancy in order to isolate service classes in an OPS/OBS network. We derive an analytical model of the proposed scheme based on reduced load Erlang fix-point analysis. A numerical evaluation shows that the isolation degree between the service classes is dependent on the amount of redundancy, system load and share of high priority traffic.","PeriodicalId":72021,"journal":{"name":"... IEEE Global Communications Conference. IEEE Global Communications Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2009-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78525770","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 : 2009-11-30DOI: 10.1109/GLOCOM.2009.5426219
Wen-Ching Chung, Li-Chun Wang, Chung-Ju Chang
The purpose of this paper is to reduce the complexity of scheduling scheme for OFDMA/SDMA system with multimedia traffic. To achieve this purpose, we propose a low-complexity beamforming-based scheduling (LCBS) scheme to solve the multi-dimensional (space, time, and frequency) radio resource allocation problem in OFDMA/SDMA systems. By utilizing a semi-orthogonal user selection (SUS) algorithm, the LCBS scheme has a good trade-off between the implementation complexity and system performance in throughput, QoS guarantee (for all traffics), and fairness guarantee (for non-real-time and best effort traffics). Simulation results show that the LCBS scheme can efficiently improve the fairness performance compared to most existing algorithms.
{"title":"A Low-Complexity Beamforming-Based Scheduling for Downlink OFDMA/SDMA Systems with Multimedia Traffic","authors":"Wen-Ching Chung, Li-Chun Wang, Chung-Ju Chang","doi":"10.1109/GLOCOM.2009.5426219","DOIUrl":"https://doi.org/10.1109/GLOCOM.2009.5426219","url":null,"abstract":"The purpose of this paper is to reduce the complexity of scheduling scheme for OFDMA/SDMA system with multimedia traffic. To achieve this purpose, we propose a low-complexity beamforming-based scheduling (LCBS) scheme to solve the multi-dimensional (space, time, and frequency) radio resource allocation problem in OFDMA/SDMA systems. By utilizing a semi-orthogonal user selection (SUS) algorithm, the LCBS scheme has a good trade-off between the implementation complexity and system performance in throughput, QoS guarantee (for all traffics), and fairness guarantee (for non-real-time and best effort traffics). Simulation results show that the LCBS scheme can efficiently improve the fairness performance compared to most existing algorithms.","PeriodicalId":72021,"journal":{"name":"... IEEE Global Communications Conference. IEEE Global Communications Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2009-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83516849","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 : 2009-01-01DOI: 10.1109/GLOCOM.2009.5426108
F. S. Donado
{"title":"Analyzing Two Conflicting Objectives of the WDM Lightpath Reconfiguration Problem","authors":"F. S. Donado","doi":"10.1109/GLOCOM.2009.5426108","DOIUrl":"https://doi.org/10.1109/GLOCOM.2009.5426108","url":null,"abstract":"","PeriodicalId":72021,"journal":{"name":"... IEEE Global Communications Conference. IEEE Global Communications Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2009-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77121724","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 : 2009-01-01DOI: 10.1109/GLOCOM.2009.5425733
H. Nguyen-Le, T. Le-Ngoc, N. Tran
The paper introduces a turbo (iterative) receiver design for joint channel estimation, synchronization and soft decoding in convolutional-coded multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems over timeand frequency-selective (doubly selective) channels. Employing the complex-exponential basis expansion model (CE-BEM) for representing doubly selective channels, a maximum likelihood (ML) objective function of carrier frequency offset (CFO) and MIMO time-varying channel responses (BEM coefficients) is formulated to develop a semiblind ML framework for joint time-variant channel estimation and synchronization. To reduce the overhead of pilot signals without sacrificing estimation accuracy, the soft bit information from a soft-input soft-output (SISO) decoder is exploited in computing soft estimates of data symbols to be functioned as pilots for further enhancing the estimation accuracy after CFO and channel acquisition phase (initial coarse estimation) using pilots. In other words, the resulting semi-blind ML estimation scheme operates in conjunction with soft decoding process in a (iteratively) progressive manner to exploit remarkable gains of turbo processing (iterative extrinsic information exchange). Simulation results show that the proposed turbo joint channel estimation and synchronization scheme offers high estimation accuracy that approaches Cramér-Rao lower bounds (CRLBs) over a wide range of CFO values under low signal-to-noise ratio (SNR) conditions.
{"title":"Iterative Receiver Design with Joint Channel Estimation and Synchronization for Coded MIMO-OFDM over Doubly Selective Channels","authors":"H. Nguyen-Le, T. Le-Ngoc, N. Tran","doi":"10.1109/GLOCOM.2009.5425733","DOIUrl":"https://doi.org/10.1109/GLOCOM.2009.5425733","url":null,"abstract":"The paper introduces a turbo (iterative) receiver design for joint channel estimation, synchronization and soft decoding in convolutional-coded multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems over timeand frequency-selective (doubly selective) channels. Employing the complex-exponential basis expansion model (CE-BEM) for representing doubly selective channels, a maximum likelihood (ML) objective function of carrier frequency offset (CFO) and MIMO time-varying channel responses (BEM coefficients) is formulated to develop a semiblind ML framework for joint time-variant channel estimation and synchronization. To reduce the overhead of pilot signals without sacrificing estimation accuracy, the soft bit information from a soft-input soft-output (SISO) decoder is exploited in computing soft estimates of data symbols to be functioned as pilots for further enhancing the estimation accuracy after CFO and channel acquisition phase (initial coarse estimation) using pilots. In other words, the resulting semi-blind ML estimation scheme operates in conjunction with soft decoding process in a (iteratively) progressive manner to exploit remarkable gains of turbo processing (iterative extrinsic information exchange). Simulation results show that the proposed turbo joint channel estimation and synchronization scheme offers high estimation accuracy that approaches Cramér-Rao lower bounds (CRLBs) over a wide range of CFO values under low signal-to-noise ratio (SNR) conditions.","PeriodicalId":72021,"journal":{"name":"... IEEE Global Communications Conference. IEEE Global Communications Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2009-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85485578","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 : 2008-12-08DOI: 10.1109/GLOCOM.2008.ECP.458
F. Piccolo
The ETSI/3GPP standardization body has defined a general location services (LCS) UMTS architecture which i) provides assistance data for mobile phones equipped with satellite navigation receivers and ii) is able to localize mobile phones not equipped with satellite navigation receivers or out of coverage. Nevertheless, the most of the already deployed systems for location-based services either assume that UMTS mobile phones are equipped with satellite navigation receivers and limit themselves to collect and transmit assistance data, or derive the position of mobile phones from the identifier of the serving cells. As the accuracy of methods based on cell identifiers depends on the size of the serving cell and it may drop to even few kilometers in case of macrocells, this paper considers the localization problem still unsolved for the UMTS mobile phones not equipped with satellite navigation receivers or out of coverage. To solve this problem, this paper proposes a new cooperative localization method for UMTS cellular networks. The idea arises from the observation that an ever increasing number of UMTS mobile phones will have an integrated satellite navigation receiver and will be able to position themselves. Thus, the proposed method consists in using the ETSI/3GPP LCS architecture to allow mobile phones without satellite navigation receivers or out of coverage to estimate their position by performing power measurements on signals emitted by mobile phones with satellite navigation receivers and known-position1.
{"title":"A New Cooperative Localization Method for UMTS Cellular Networks","authors":"F. Piccolo","doi":"10.1109/GLOCOM.2008.ECP.458","DOIUrl":"https://doi.org/10.1109/GLOCOM.2008.ECP.458","url":null,"abstract":"The ETSI/3GPP standardization body has defined a general location services (LCS) UMTS architecture which i) provides assistance data for mobile phones equipped with satellite navigation receivers and ii) is able to localize mobile phones not equipped with satellite navigation receivers or out of coverage. Nevertheless, the most of the already deployed systems for location-based services either assume that UMTS mobile phones are equipped with satellite navigation receivers and limit themselves to collect and transmit assistance data, or derive the position of mobile phones from the identifier of the serving cells. As the accuracy of methods based on cell identifiers depends on the size of the serving cell and it may drop to even few kilometers in case of macrocells, this paper considers the localization problem still unsolved for the UMTS mobile phones not equipped with satellite navigation receivers or out of coverage. To solve this problem, this paper proposes a new cooperative localization method for UMTS cellular networks. The idea arises from the observation that an ever increasing number of UMTS mobile phones will have an integrated satellite navigation receiver and will be able to position themselves. Thus, the proposed method consists in using the ETSI/3GPP LCS architecture to allow mobile phones without satellite navigation receivers or out of coverage to estimate their position by performing power measurements on signals emitted by mobile phones with satellite navigation receivers and known-position1.","PeriodicalId":72021,"journal":{"name":"... IEEE Global Communications Conference. IEEE Global Communications Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83472771","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 : 2008-01-01DOI: 10.1109/GLOCOM.2008.ECP.836
Liangbin Li, Z. Fang, Y. Zhu, Zongxin Wang
{"title":"Generalized Differential Transmission for STBC Systems","authors":"Liangbin Li, Z. Fang, Y. Zhu, Zongxin Wang","doi":"10.1109/GLOCOM.2008.ECP.836","DOIUrl":"https://doi.org/10.1109/GLOCOM.2008.ECP.836","url":null,"abstract":"","PeriodicalId":72021,"journal":{"name":"... IEEE Global Communications Conference. IEEE Global Communications Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77881006","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, we are proposing a scheme called RECHOKe (REpeatedly CHOose and keep for malicious flows, REpeatedly CHOose and Kill for non-malicious flows) to be used for detecting, controlling and punishing of malicious flows in IP networks. It is an extension of xCHOKe, CHOKe and RED-PD schemes, combining both CHOKe hit and RED drop/mark histories, to detect, control and punish these flows more accurately while providing better protection to non-malicious flows. However, unlike xCHOKe and CHOKe, RECHOKe does not drop packets during CHOKe hits; thereby eliminating the complexity of dropping or marking randomly selected packets already queued and the unreliability of CHOKe hits. We analyze xCHOKe and RECHOKe in detail using ns-2 and show that RECHOKe performs better than RED, CHOKe and xCHOKe which are limited in what they can achieve as malicious flows get much more than their fair share and non-malicious flows get mistakenly penalized.
{"title":"RECHOKe: A Scheme for Detection, Control and Punishment of Malicious Flows in IP Networks","authors":"V. Govindaswamy, G. Záruba, G. Balasekaran","doi":"10.1109/GLOCOM.2007.11","DOIUrl":"https://doi.org/10.1109/GLOCOM.2007.11","url":null,"abstract":"In this paper, we are proposing a scheme called RECHOKe (REpeatedly CHOose and keep for malicious flows, REpeatedly CHOose and Kill for non-malicious flows) to be used for detecting, controlling and punishing of malicious flows in IP networks. It is an extension of xCHOKe, CHOKe and RED-PD schemes, combining both CHOKe hit and RED drop/mark histories, to detect, control and punish these flows more accurately while providing better protection to non-malicious flows. However, unlike xCHOKe and CHOKe, RECHOKe does not drop packets during CHOKe hits; thereby eliminating the complexity of dropping or marking randomly selected packets already queued and the unreliability of CHOKe hits. We analyze xCHOKe and RECHOKe in detail using ns-2 and show that RECHOKe performs better than RED, CHOKe and xCHOKe which are limited in what they can achieve as malicious flows get much more than their fair share and non-malicious flows get mistakenly penalized.","PeriodicalId":72021,"journal":{"name":"... IEEE Global Communications Conference. IEEE Global Communications Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81909372","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}
Nowadays a lot of effort is spent on developing OFDM- based inexpensive wireless transceivers. Direct-conversion radio frequency transceivers are appealing because they avoid costly IF analog components. This kind of transceivers imply analog RF I/Q separation. The mismatch between the analog components in the in-phase and quadrature branches introduces an unwanted in-band interference. Unfortunately, OFDM-based systems are very sensitive to I/Q mismatch, mostly when high order mod- ulation schemes are applied. A digital compensation of this unwanted ef- fect is required. In this paper, we developed an iterative method for es- timating and compensating the transmitter/receiver frequency-dependent I/Q imbalance jointly with the propagation channel in the frequency do- main. The new estimation technique resorts to the iterative Expectation- Maximization algorithm in order converge to the ML estimation for both channel and IQ imbalance coefficients in presence of unknown transmitted data symbols. Although the the estimation may be perform in the absence of known pilot symbols, the algorithm provides flexibility in terms of pi- lot sequence, allocation and load in order to improve its convergence. An advanced low complexity equalizer is proposed which compensates for the frequency-dependent IQ imbalance. Simulation results show optimal per- formance even in the absence of any pilot symbol and large IQ mismatches. The proposed technique enables the system to achieve high SNRs.
{"title":"EM Based Frequency-Dependent Transmit/Receive IQ Imbalance Estimationand Compensation in OFDM-Based Transceivers","authors":"Eduardo Lopez-Estraviz, L. Perre","doi":"10.1109/GLOCOM.2007.813","DOIUrl":"https://doi.org/10.1109/GLOCOM.2007.813","url":null,"abstract":"Nowadays a lot of effort is spent on developing OFDM- based inexpensive wireless transceivers. Direct-conversion radio frequency transceivers are appealing because they avoid costly IF analog components. This kind of transceivers imply analog RF I/Q separation. The mismatch between the analog components in the in-phase and quadrature branches introduces an unwanted in-band interference. Unfortunately, OFDM-based systems are very sensitive to I/Q mismatch, mostly when high order mod- ulation schemes are applied. A digital compensation of this unwanted ef- fect is required. In this paper, we developed an iterative method for es- timating and compensating the transmitter/receiver frequency-dependent I/Q imbalance jointly with the propagation channel in the frequency do- main. The new estimation technique resorts to the iterative Expectation- Maximization algorithm in order converge to the ML estimation for both channel and IQ imbalance coefficients in presence of unknown transmitted data symbols. Although the the estimation may be perform in the absence of known pilot symbols, the algorithm provides flexibility in terms of pi- lot sequence, allocation and load in order to improve its convergence. An advanced low complexity equalizer is proposed which compensates for the frequency-dependent IQ imbalance. Simulation results show optimal per- formance even in the absence of any pilot symbol and large IQ mismatches. The proposed technique enables the system to achieve high SNRs.","PeriodicalId":72021,"journal":{"name":"... IEEE Global Communications Conference. IEEE Global Communications Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87885714","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}
{"title":"Combined Cross Layer Design and HARQ for TDD Multiuser Systems with Outdated CSIT","authors":"Rui Wang, V. Lau","doi":"10.1109/GLOCOM.2007.637","DOIUrl":"https://doi.org/10.1109/GLOCOM.2007.637","url":null,"abstract":"","PeriodicalId":72021,"journal":{"name":"... IEEE Global Communications Conference. IEEE Global Communications Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83238767","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}
N. Efthymiopoulos, Athanasios Christakidis, S. Denazis, O. Koufopavlou
{"title":"Enabling Locality in a Balanced Peer-to-Peer Overlay","authors":"N. Efthymiopoulos, Athanasios Christakidis, S. Denazis, O. Koufopavlou","doi":"10.1109/GLOCOM.2006.244","DOIUrl":"https://doi.org/10.1109/GLOCOM.2006.244","url":null,"abstract":"","PeriodicalId":72021,"journal":{"name":"... IEEE Global Communications Conference. IEEE Global Communications Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89943801","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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