Pub Date : 2011-05-08DOI: 10.1109/CTS.2011.5898937
H. Ghasvari, B. Khalaj, M. Raayatpanah
In this paper, we consider the problem of Minimum-Cost Multicast (MCM) sub-graph optimization with network coding subject to uncertainty in link costs. A number of uncertainty sets such as ellipsoids and bounded polyhedral are taken into account. A robust optimization model is developed to obtain the optimal sub-graph by replacing an uncertain model of MCM by its Robust Counterpart (RC). Then, the analytic and computational optimization tools to obtain robust solutions of an uncertain MCM problem via solving the corresponding explicitly-stated convex RC program is developed and validated through simulations.
{"title":"Robust Minimum-Cost Multicast with network coding","authors":"H. Ghasvari, B. Khalaj, M. Raayatpanah","doi":"10.1109/CTS.2011.5898937","DOIUrl":"https://doi.org/10.1109/CTS.2011.5898937","url":null,"abstract":"In this paper, we consider the problem of Minimum-Cost Multicast (MCM) sub-graph optimization with network coding subject to uncertainty in link costs. A number of uncertainty sets such as ellipsoids and bounded polyhedral are taken into account. A robust optimization model is developed to obtain the optimal sub-graph by replacing an uncertain model of MCM by its Robust Counterpart (RC). Then, the analytic and computational optimization tools to obtain robust solutions of an uncertain MCM problem via solving the corresponding explicitly-stated convex RC program is developed and validated through simulations.","PeriodicalId":142306,"journal":{"name":"2011 18th International Conference on Telecommunications","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124928884","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 : 2011-05-08DOI: 10.1109/CTS.2011.5898950
Majid Bavand, P. Azmi
A novel receiver optimization for spatial multiple access scenario is studied in this paper where each user uses single antenna and multiple antenna array is used at the base station. To achieve space division multiple access, the newly introduced minimum probability of error (MPE) beamforming method is used instead of the conventional minimum mean square error (MMSE) beamforming. To increase the number of admitted users to the system, a new set of beamforming weight vectors is obtained for non-admitted users by minimizing their error probability conditioning on the detection of the admitted users. Moreover, a heuristic algorithm is presented to utilize the proposed detection-based minimum probability of error beamforming in a successive manner. By numerical analysis it is shown that the proposed method is able to support more users than MPE and MMSE beamforming in addition to providing better performance in the sense of probability of error.
{"title":"Successive detection based minimum probability of error beamforming","authors":"Majid Bavand, P. Azmi","doi":"10.1109/CTS.2011.5898950","DOIUrl":"https://doi.org/10.1109/CTS.2011.5898950","url":null,"abstract":"A novel receiver optimization for spatial multiple access scenario is studied in this paper where each user uses single antenna and multiple antenna array is used at the base station. To achieve space division multiple access, the newly introduced minimum probability of error (MPE) beamforming method is used instead of the conventional minimum mean square error (MMSE) beamforming. To increase the number of admitted users to the system, a new set of beamforming weight vectors is obtained for non-admitted users by minimizing their error probability conditioning on the detection of the admitted users. Moreover, a heuristic algorithm is presented to utilize the proposed detection-based minimum probability of error beamforming in a successive manner. By numerical analysis it is shown that the proposed method is able to support more users than MPE and MMSE beamforming in addition to providing better performance in the sense of probability of error.","PeriodicalId":142306,"journal":{"name":"2011 18th International Conference on Telecommunications","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122962679","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 : 2011-05-08DOI: 10.1109/CTS.2011.5898922
Hong Du, Zaixue Wei, Yanhui Yang, Dacheng Yang
In cognitive radio networks, spectrum sensing is essential for the protection of primary users, enabling cognitive users to vacate channels immediately upon detection of primary users. In IEEE 802.22 standard, it is important to meet detectability requirements for in-band sensing, such as the maximum allowed probability of miss-detection and false-alarm. In this paper, we propose a periodic in-band sensing scheduling algorithm that mitigates sensing overhead and average detection time while meeting the detectability requirements within channel detection time (CDT). In particular, we bring forth new idea of average detection time. In addition, we also derive the formulas of sensing overhead and average detection time in a CDT. Furthermore, we investigate that how to obtain the optimal sensing period and sensing time under the detectability requirements. Finally, the simulation results show that longer sensing period leads to lower sensing overhead and bring about higher average detection time in the CDT.
{"title":"Sensing overhead and average detection time mitigation for sensing scheduling algorithm","authors":"Hong Du, Zaixue Wei, Yanhui Yang, Dacheng Yang","doi":"10.1109/CTS.2011.5898922","DOIUrl":"https://doi.org/10.1109/CTS.2011.5898922","url":null,"abstract":"In cognitive radio networks, spectrum sensing is essential for the protection of primary users, enabling cognitive users to vacate channels immediately upon detection of primary users. In IEEE 802.22 standard, it is important to meet detectability requirements for in-band sensing, such as the maximum allowed probability of miss-detection and false-alarm. In this paper, we propose a periodic in-band sensing scheduling algorithm that mitigates sensing overhead and average detection time while meeting the detectability requirements within channel detection time (CDT). In particular, we bring forth new idea of average detection time. In addition, we also derive the formulas of sensing overhead and average detection time in a CDT. Furthermore, we investigate that how to obtain the optimal sensing period and sensing time under the detectability requirements. Finally, the simulation results show that longer sensing period leads to lower sensing overhead and bring about higher average detection time in the CDT.","PeriodicalId":142306,"journal":{"name":"2011 18th International Conference on Telecommunications","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122583376","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 : 2011-05-08DOI: 10.1109/CTS.2011.5898925
Serhan Yarkan, B. U. Töreyin, K. Qaraqe, A. Cetin
Cooperative spectrum sensing methods in the literature assume a static communication scenario with fixed channel and propagation environment characteristics. In order to maintain the level of sensing reliability and performance under changing channel and environment conditions, in this study, an online adaptive cooperation scheme is proposed. Energy detection data from each cooperating sensor are fused together by an adaptive weighted linear combination at the fusion center. Weight update operation is performed online through the use of orthogonal projections onto convex sets (POCS). Also, in this paper, an end-to-end methodology for a flexible experimental setup is proposed. This setup is specifically deployed to emulate the proposed adaptive cooperation scheme for spectrum sensing and validate its practical use in cognitive radio systems.
{"title":"An experimental validation of an online adaptive cooperation scheme for spectrum sensing","authors":"Serhan Yarkan, B. U. Töreyin, K. Qaraqe, A. Cetin","doi":"10.1109/CTS.2011.5898925","DOIUrl":"https://doi.org/10.1109/CTS.2011.5898925","url":null,"abstract":"Cooperative spectrum sensing methods in the literature assume a static communication scenario with fixed channel and propagation environment characteristics. In order to maintain the level of sensing reliability and performance under changing channel and environment conditions, in this study, an online adaptive cooperation scheme is proposed. Energy detection data from each cooperating sensor are fused together by an adaptive weighted linear combination at the fusion center. Weight update operation is performed online through the use of orthogonal projections onto convex sets (POCS). Also, in this paper, an end-to-end methodology for a flexible experimental setup is proposed. This setup is specifically deployed to emulate the proposed adaptive cooperation scheme for spectrum sensing and validate its practical use in cognitive radio systems.","PeriodicalId":142306,"journal":{"name":"2011 18th International Conference on Telecommunications","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128512651","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 : 2011-05-08DOI: 10.1109/CTS.2011.5898900
A. Mishra, Ioannis Tomkos
This paper is focused on the proposed novel techniques for cost-effective and high performance optical OFDM systems. We propose a novel cost-effective optical comb-line generation source to produce 8-sub-carriers with spectral flatness of <1dB with drive amplitudes of 1Vpi employing single dual-drive Mach-Zehnder-Modulator and show a comparison with other efficient comb-generator methods. We also propose a novel optical iFFT-based implementation for 87.5 Gbit/s optical NRZ-OFDM generations. It is shown that the cross-talk introduced by imperfect WDM demultiplexer to separate sub-carriers for modulation can be significantly reduced.
{"title":"A novel cost-effective combline generation and cross-talk mitigation in optical OFDM signal using optical iFFT circuits","authors":"A. Mishra, Ioannis Tomkos","doi":"10.1109/CTS.2011.5898900","DOIUrl":"https://doi.org/10.1109/CTS.2011.5898900","url":null,"abstract":"This paper is focused on the proposed novel techniques for cost-effective and high performance optical OFDM systems. We propose a novel cost-effective optical comb-line generation source to produce 8-sub-carriers with spectral flatness of <1dB with drive amplitudes of 1Vpi employing single dual-drive Mach-Zehnder-Modulator and show a comparison with other efficient comb-generator methods. We also propose a novel optical iFFT-based implementation for 87.5 Gbit/s optical NRZ-OFDM generations. It is shown that the cross-talk introduced by imperfect WDM demultiplexer to separate sub-carriers for modulation can be significantly reduced.","PeriodicalId":142306,"journal":{"name":"2011 18th International Conference on Telecommunications","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126671399","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 : 2011-05-08DOI: 10.1109/CTS.2011.5898920
S. Amiralizadeh, K. Mehrany
The performance of a three-dimensional optical code-division multiple-access system based on polarization-wavelength-time codes is investigated. The unwanted effects of multiple access interference are first studied and an accurate enough expression is given for the upper bound of the bit error rate. The proposed expression is obtained by decomposing the three-dimensional polarization-wavelength-time codes into horizontally and vertically polarized two-dimensional wavelength-time codes that are assumed to be statistically independent. It is shown by Monte Carlo simulation that the assumption of independence gives accurate enough bit error rate, whenever the number of chips is much larger than the number of wavelengths. The impact of the beat noise is also studied by approximating its distribution as Gaussian. It is shown that beat noise in a network having three-dimensionally encoded signals is not as important as it is in a network having two-dimensionally encoded ones.
{"title":"Analytical study of multiple access interference and beat noise in polarization-wavelength-time optical CDMA systems","authors":"S. Amiralizadeh, K. Mehrany","doi":"10.1109/CTS.2011.5898920","DOIUrl":"https://doi.org/10.1109/CTS.2011.5898920","url":null,"abstract":"The performance of a three-dimensional optical code-division multiple-access system based on polarization-wavelength-time codes is investigated. The unwanted effects of multiple access interference are first studied and an accurate enough expression is given for the upper bound of the bit error rate. The proposed expression is obtained by decomposing the three-dimensional polarization-wavelength-time codes into horizontally and vertically polarized two-dimensional wavelength-time codes that are assumed to be statistically independent. It is shown by Monte Carlo simulation that the assumption of independence gives accurate enough bit error rate, whenever the number of chips is much larger than the number of wavelengths. The impact of the beat noise is also studied by approximating its distribution as Gaussian. It is shown that beat noise in a network having three-dimensionally encoded signals is not as important as it is in a network having two-dimensionally encoded ones.","PeriodicalId":142306,"journal":{"name":"2011 18th International Conference on Telecommunications","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127851819","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 : 2011-05-08DOI: 10.1109/CTS.2011.5898951
Safa Isam, I. Darwazeh
Spectrally efficient FDM (SEFDM) systems are new and attractive multicarrier systems that can significantly enhance spectral utilization. However, as a multicarrier system SEFDM is prone to high peak to average power ratio (PAPR). In this work we present for the first time a study of the PAPR in SEFDM systems. We explore the performance of standard PAPR reduction techniques and propose a novel PAPR reduction algorithm, based on sliding a time window across an extended SEFDM symbol period, therefore termed the SLiding Window (SLW) PAPR reduction technique. Numerical simulations confirm this new technique efficacy in PAPR reduction and show no side effects. Furthermore, a complete transmitter that employs SLW is proposed based on the SEFDM IDFT transmitter. SLW shows remarkable PAPR reduction with no spectral spreading or Bit Error Rate (BER) compromises at a much reduced complexity when compared to standard Partial Transmit Sequence (PTS) and Selective Mapping (SLM) PAPR reduction techniques.
{"title":"Peak to average power ratio reduction in spectrally efficient FDM systems","authors":"Safa Isam, I. Darwazeh","doi":"10.1109/CTS.2011.5898951","DOIUrl":"https://doi.org/10.1109/CTS.2011.5898951","url":null,"abstract":"Spectrally efficient FDM (SEFDM) systems are new and attractive multicarrier systems that can significantly enhance spectral utilization. However, as a multicarrier system SEFDM is prone to high peak to average power ratio (PAPR). In this work we present for the first time a study of the PAPR in SEFDM systems. We explore the performance of standard PAPR reduction techniques and propose a novel PAPR reduction algorithm, based on sliding a time window across an extended SEFDM symbol period, therefore termed the SLiding Window (SLW) PAPR reduction technique. Numerical simulations confirm this new technique efficacy in PAPR reduction and show no side effects. Furthermore, a complete transmitter that employs SLW is proposed based on the SEFDM IDFT transmitter. SLW shows remarkable PAPR reduction with no spectral spreading or Bit Error Rate (BER) compromises at a much reduced complexity when compared to standard Partial Transmit Sequence (PTS) and Selective Mapping (SLM) PAPR reduction techniques.","PeriodicalId":142306,"journal":{"name":"2011 18th International Conference on Telecommunications","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114405856","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 : 2011-05-08DOI: 10.1109/CTS.2011.5898961
Ryma Abassi, S. Fatmi
A security policy constitutes one of the major actors in the protection of communication networks but can be one of their drawbacks too. This can be the case if it is inadequate to the security requirements for example. For this, a security policy has to be checked before its real deployment. In this paper, we propose three checking activities each of which is adapted to a given phase of the policy deployment process. This activities deal with the SP validation, the SP testing and the multi-SP conflict management. Our techniques are inspired by the well established techniques of the software engineering for which we have found some similarities with the security domain.
{"title":"Using security policies in a network securing process","authors":"Ryma Abassi, S. Fatmi","doi":"10.1109/CTS.2011.5898961","DOIUrl":"https://doi.org/10.1109/CTS.2011.5898961","url":null,"abstract":"A security policy constitutes one of the major actors in the protection of communication networks but can be one of their drawbacks too. This can be the case if it is inadequate to the security requirements for example. For this, a security policy has to be checked before its real deployment. In this paper, we propose three checking activities each of which is adapted to a given phase of the policy deployment process. This activities deal with the SP validation, the SP testing and the multi-SP conflict management. Our techniques are inspired by the well established techniques of the software engineering for which we have found some similarities with the security domain.","PeriodicalId":142306,"journal":{"name":"2011 18th International Conference on Telecommunications","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125480303","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 : 2011-05-08DOI: 10.1109/CTS.2011.5898929
Pavlos Kosmides, A. Rouskas, M. Anagnostou
The evolution of wireless access networks has led to the vision of an integrated heterogeneous wireless environment consisting of various Radio Access Technologies (RATs). In such an environment, users with multimode terminals can seamlessly change from one RAT to another RAT attempting to maximize their satisfaction level, while providers may carefully utilize without overloading their subsystems. In this paper, we focus on the Network Selection problem to allocate terminals to most appropriate RATs by jointly examining both users and providers' preferences. We introduce a utility-based optimization function and formulate the terminal assignment problem as an optimization problem which is recognized as NP-hard. We propose a Greedy heuristic which exploits a metric that measures the utility gained versus the capacity resource spent for each allocation and confirm its superior performance against three Bin-Packing heuristics.
{"title":"Network selection in heterogeneous wireless environments","authors":"Pavlos Kosmides, A. Rouskas, M. Anagnostou","doi":"10.1109/CTS.2011.5898929","DOIUrl":"https://doi.org/10.1109/CTS.2011.5898929","url":null,"abstract":"The evolution of wireless access networks has led to the vision of an integrated heterogeneous wireless environment consisting of various Radio Access Technologies (RATs). In such an environment, users with multimode terminals can seamlessly change from one RAT to another RAT attempting to maximize their satisfaction level, while providers may carefully utilize without overloading their subsystems. In this paper, we focus on the Network Selection problem to allocate terminals to most appropriate RATs by jointly examining both users and providers' preferences. We introduce a utility-based optimization function and formulate the terminal assignment problem as an optimization problem which is recognized as NP-hard. We propose a Greedy heuristic which exploits a metric that measures the utility gained versus the capacity resource spent for each allocation and confirm its superior performance against three Bin-Packing heuristics.","PeriodicalId":142306,"journal":{"name":"2011 18th International Conference on Telecommunications","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125587562","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 : 2011-05-08DOI: 10.1109/CTS.2011.5898938
P. Fines, E. Christofylaki, H. Aghvami
The proposed technique applies to full duplex mobile-to-mobile pair wise communication via a common centralized node such as a base station or satellite. In the uplink, a multiuser receiver is employed using Turbo Code Division Multiple Access (TCDMA) optimized for two narrowband bursts generated by the two users. In the downlink, a single burst using network coding is addressed to both users. Applying the proposed technique to mobile-to-mobile applications, the radio resources are used very efficiently since the network capacity is almost doubled and the radio resource management is simplified so that message delivery time is halved.
{"title":"An efficient method for data exchange using network coding and narrowband multiuser detection","authors":"P. Fines, E. Christofylaki, H. Aghvami","doi":"10.1109/CTS.2011.5898938","DOIUrl":"https://doi.org/10.1109/CTS.2011.5898938","url":null,"abstract":"The proposed technique applies to full duplex mobile-to-mobile pair wise communication via a common centralized node such as a base station or satellite. In the uplink, a multiuser receiver is employed using Turbo Code Division Multiple Access (TCDMA) optimized for two narrowband bursts generated by the two users. In the downlink, a single burst using network coding is addressed to both users. Applying the proposed technique to mobile-to-mobile applications, the radio resources are used very efficiently since the network capacity is almost doubled and the radio resource management is simplified so that message delivery time is halved.","PeriodicalId":142306,"journal":{"name":"2011 18th International Conference on Telecommunications","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127104109","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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