Pub Date : 2014-12-01DOI: 10.1109/GLOCOM.2014.7037314
Xinyu Gao, L. Dai, Yuting Hu, Zhongxu Wang, Zhaocheng Wang
For uplink large-scale MIMO systems, linear minimum mean square error (MMSE) signal detection algorithm is near-optimal but involves matrix inversion with high complexity. In this paper, we propose a low-complexity signal detection algorithm based on the successive overrelaxation (SOR) method to avoid the complicated matrix inversion. We first prove a special property that the MMSE filtering matrix is symmetric positive definite for uplink large-scale MIMO systems, which is the premise for the SOR method. Then a low-complexity iterative signal detection algorithm based on the SOR method as well as the convergence proof is proposed. The analysis shows that the proposed scheme can reduce the computational complexity from O(K3) to O(K2), where K is the number of users. Finally, we verify through simulation results that the proposed algorithm outperforms the recently proposed Neumann series approximation algorithm, and achieves the near-optimal performance of the classical MMSE algorithm with a small number of iterations.
{"title":"Matrix inversion-less signal detection using SOR method for uplink large-scale MIMO systems","authors":"Xinyu Gao, L. Dai, Yuting Hu, Zhongxu Wang, Zhaocheng Wang","doi":"10.1109/GLOCOM.2014.7037314","DOIUrl":"https://doi.org/10.1109/GLOCOM.2014.7037314","url":null,"abstract":"For uplink large-scale MIMO systems, linear minimum mean square error (MMSE) signal detection algorithm is near-optimal but involves matrix inversion with high complexity. In this paper, we propose a low-complexity signal detection algorithm based on the successive overrelaxation (SOR) method to avoid the complicated matrix inversion. We first prove a special property that the MMSE filtering matrix is symmetric positive definite for uplink large-scale MIMO systems, which is the premise for the SOR method. Then a low-complexity iterative signal detection algorithm based on the SOR method as well as the convergence proof is proposed. The analysis shows that the proposed scheme can reduce the computational complexity from O(K3) to O(K2), where K is the number of users. Finally, we verify through simulation results that the proposed algorithm outperforms the recently proposed Neumann series approximation algorithm, and achieves the near-optimal performance of the classical MMSE algorithm with a small number of iterations.","PeriodicalId":6492,"journal":{"name":"2014 IEEE Global Communications Conference","volume":"68 1","pages":"3291-3295"},"PeriodicalIF":0.0,"publicationDate":"2014-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81461851","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 : 2014-12-01DOI: 10.1109/GLOCOM.2014.7036952
D. Zhai, Min Sheng, Xijun Wang, Yan Zhang
We investigate the local connectivity of cognitive radio ad hoc networks (CRAHNs), i.e., node degree and probability of node isolation. The local connectivity of CRAHNs depends on not only its own network parameters but also the primary networks. To analyze the local connectivity, we use stochastic geometry and probability theory to derive the distribution of node degree, probability of available spectrum and probability of node isolation of the Secondary Users (SUs). The relation between the local connectivity of CRAHNs and the parameters of both primary and secondary networks is given. Theoretical analysis and simulation results indicate that the average node degree of SUs scales linearly for increases in the density of SUs with the slope determined by the density of Primary Users (PUs). It also indicates that the SUs' node isolation probability is largely determined by the density of PUs.
{"title":"Local connectivity of cognitive radio Ad hoc networks","authors":"D. Zhai, Min Sheng, Xijun Wang, Yan Zhang","doi":"10.1109/GLOCOM.2014.7036952","DOIUrl":"https://doi.org/10.1109/GLOCOM.2014.7036952","url":null,"abstract":"We investigate the local connectivity of cognitive radio ad hoc networks (CRAHNs), i.e., node degree and probability of node isolation. The local connectivity of CRAHNs depends on not only its own network parameters but also the primary networks. To analyze the local connectivity, we use stochastic geometry and probability theory to derive the distribution of node degree, probability of available spectrum and probability of node isolation of the Secondary Users (SUs). The relation between the local connectivity of CRAHNs and the parameters of both primary and secondary networks is given. Theoretical analysis and simulation results indicate that the average node degree of SUs scales linearly for increases in the density of SUs with the slope determined by the density of Primary Users (PUs). It also indicates that the SUs' node isolation probability is largely determined by the density of PUs.","PeriodicalId":6492,"journal":{"name":"2014 IEEE Global Communications Conference","volume":"1 1","pages":"1078-1083"},"PeriodicalIF":0.0,"publicationDate":"2014-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81489402","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 : 2014-12-01DOI: 10.1109/GLOCOM.2014.7037487
M. Tariq, Mirza Uzair Baig, M. Uppal
We consider a relay-aided wireless multicast channel in which all transmissions are constrained to be drawn from M-ary PAM constellations. In order to deal with heterogeneous channel conditions at different receivers, we propose a practical layered compress-and-forward (CF) scheme that utilizes scalar quantization concatenated with Slepian-Wolf coding. Exploiting the inherent unequal protection provided to different bit-planes of an M-ary PAM constellation, the layering is accomplished through an intelligent mapping of the quantization bits to the relay's transmission symbols. This allows users to adapt by extracting as many CF cooperation layers as allowed by the channel conditions. By analyzing information theoretic performance, we find that the proposed scheme performs significantly better than the traditional unlayered CF for a wide variety of channel conditions; our best results indicate a performance gap of 1.1 dB between the two.
{"title":"Layered compress-and-forward cooperation in wireless multicast with M-ary PAM transmissions","authors":"M. Tariq, Mirza Uzair Baig, M. Uppal","doi":"10.1109/GLOCOM.2014.7037487","DOIUrl":"https://doi.org/10.1109/GLOCOM.2014.7037487","url":null,"abstract":"We consider a relay-aided wireless multicast channel in which all transmissions are constrained to be drawn from M-ary PAM constellations. In order to deal with heterogeneous channel conditions at different receivers, we propose a practical layered compress-and-forward (CF) scheme that utilizes scalar quantization concatenated with Slepian-Wolf coding. Exploiting the inherent unequal protection provided to different bit-planes of an M-ary PAM constellation, the layering is accomplished through an intelligent mapping of the quantization bits to the relay's transmission symbols. This allows users to adapt by extracting as many CF cooperation layers as allowed by the channel conditions. By analyzing information theoretic performance, we find that the proposed scheme performs significantly better than the traditional unlayered CF for a wide variety of channel conditions; our best results indicate a performance gap of 1.1 dB between the two.","PeriodicalId":6492,"journal":{"name":"2014 IEEE Global Communications Conference","volume":"13 1","pages":"4324-4329"},"PeriodicalIF":0.0,"publicationDate":"2014-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82400672","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 : 2014-12-01DOI: 10.1109/GLOCOM.2014.7036964
Louis Anegekuh, Lingfen Sun, E. Ifeachor
Recently, crowdsourcing has emerged as a cheaper and quicker alternative to traditional laboratory based Quality of Experience (QoE) evaluation for video streaming services. Crowdsourcing is a process of recruiting anonymous members of the public to solve/perform different tasks without supervision. This approach of seeking solutions from the public has been enhanced by ubiquitous internet connectivity, low cost and the ease to recruit workers without geographical restrictions. Although crowdsourcing makes it possible to save cost and reach a large group of people to perform subjective video quality testing, challenges such as validity of results and the trustworthiness of workers still remain unresolved. In this paper, we attempt to address some of these challenges by developing a screening algorithm that is able to determine the validity and trustworthiness of crowdsourcing video QoE evaluation results. This algorithm is based on evaluator's extracted data (e.g. Network IP addresses, network devices and browser information, time spent on the crowdsourcing platform, date and grading patterns). To determine the performance of this algorithm, we carried out a separate controlled laboratory based subjective video quality testing. This test enables us to determine how screened crowdsourcing results correlate with lab based results. Preliminary results show that crowdsourcing results can be improved by up to 59% when the proposed screening algorithm is applied. Moreover, the results support our assertion that crowdsourcing can provide reliable video QoE measurements if proper screening is performed on the test results.
{"title":"A screening methodology for crowdsourcing video QoE evaluation","authors":"Louis Anegekuh, Lingfen Sun, E. Ifeachor","doi":"10.1109/GLOCOM.2014.7036964","DOIUrl":"https://doi.org/10.1109/GLOCOM.2014.7036964","url":null,"abstract":"Recently, crowdsourcing has emerged as a cheaper and quicker alternative to traditional laboratory based Quality of Experience (QoE) evaluation for video streaming services. Crowdsourcing is a process of recruiting anonymous members of the public to solve/perform different tasks without supervision. This approach of seeking solutions from the public has been enhanced by ubiquitous internet connectivity, low cost and the ease to recruit workers without geographical restrictions. Although crowdsourcing makes it possible to save cost and reach a large group of people to perform subjective video quality testing, challenges such as validity of results and the trustworthiness of workers still remain unresolved. In this paper, we attempt to address some of these challenges by developing a screening algorithm that is able to determine the validity and trustworthiness of crowdsourcing video QoE evaluation results. This algorithm is based on evaluator's extracted data (e.g. Network IP addresses, network devices and browser information, time spent on the crowdsourcing platform, date and grading patterns). To determine the performance of this algorithm, we carried out a separate controlled laboratory based subjective video quality testing. This test enables us to determine how screened crowdsourcing results correlate with lab based results. Preliminary results show that crowdsourcing results can be improved by up to 59% when the proposed screening algorithm is applied. Moreover, the results support our assertion that crowdsourcing can provide reliable video QoE measurements if proper screening is performed on the test results.","PeriodicalId":6492,"journal":{"name":"2014 IEEE Global Communications Conference","volume":"8 1","pages":"1152-1157"},"PeriodicalIF":0.0,"publicationDate":"2014-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82508473","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 : 2014-12-01DOI: 10.1109/GLOCOM.2014.7036895
F. Aziz, J. Shamma, Gordon L. Stüber
Commercial LTE networks are being studied for mission-critical applications, such as public safety and smart grid communications. In this paper, LTE networks are shown vulnerable to Denial-of-Service (DOS) and loss of service attacks from smart jammers, who may employ simple narrowband jamming techniques to attack without any need to hack the network or its users. We modeled the utilities of jamming and anti-jamming actions played by the jammer and the network under the framework of single-shot and repeated Bayesian games. In a single-shot game formulation the only Nash Equilibria (NE) are pure strategy equilibria at which network utility is severely compromised. We propose a repeated-game learning and strategy algorithm for the network that outperforms single-shot games by a significant margin. Furthermore, all of our proposed actions and algorithms can be implemented with current technology.
{"title":"Resilience of LTE networks against smart jamming attacks","authors":"F. Aziz, J. Shamma, Gordon L. Stüber","doi":"10.1109/GLOCOM.2014.7036895","DOIUrl":"https://doi.org/10.1109/GLOCOM.2014.7036895","url":null,"abstract":"Commercial LTE networks are being studied for mission-critical applications, such as public safety and smart grid communications. In this paper, LTE networks are shown vulnerable to Denial-of-Service (DOS) and loss of service attacks from smart jammers, who may employ simple narrowband jamming techniques to attack without any need to hack the network or its users. We modeled the utilities of jamming and anti-jamming actions played by the jammer and the network under the framework of single-shot and repeated Bayesian games. In a single-shot game formulation the only Nash Equilibria (NE) are pure strategy equilibria at which network utility is severely compromised. We propose a repeated-game learning and strategy algorithm for the network that outperforms single-shot games by a significant margin. Furthermore, all of our proposed actions and algorithms can be implemented with current technology.","PeriodicalId":6492,"journal":{"name":"2014 IEEE Global Communications Conference","volume":"41 1","pages":"734-739"},"PeriodicalIF":0.0,"publicationDate":"2014-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76297648","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 : 2014-12-01DOI: 10.1109/GLOCOM.2014.7037516
Bin Cao, G. Feng, Yun Li, M. Daneshmand
The performance gain of cooperative communications depends heavily on the selection of relay. Most of existing relay selection methods aim at maximizing cooperative gain by selecting appropriate relay, without taking into account the adverse effect brought by cooperative communications: extra interferences introduced by relay transmission (called cooperation interference). Thus the derived performance gain could be inaccurate and/or the selected relay may be not optimal. In this paper, we address the assignment of relays for multiple communication sessions using cooperative communications in a wireless network. We first thoroughly investigate the adverse effect brought by using relays, and derive the cooperation gain with consideration of cooperation interference. Based on the insights of our investigation, we propose a method of assigning relays to individual transmission flows while taking into account cooperation interference in cooperative communications. In order to tradeoff the advantage and adverse effect caused by relay transmissions, we use an auction approach to address relay assignment of cooperative communications. Specifically, we propose a Single round double Auction Scheme (SAS) for centralized wireless network and a Multiple rounds sequential Auction Scheme (MAS) for decentralized wireless network for relay assignment. We conduct extensive simulation experiments to validate the effectiveness of SAS and MAS. The significance of the impact of cooperation interference, improvement of system throughput and energy efficiency are demonstrated by numerical results.
{"title":"Auction-based relay assignment in cooperative communications","authors":"Bin Cao, G. Feng, Yun Li, M. Daneshmand","doi":"10.1109/GLOCOM.2014.7037516","DOIUrl":"https://doi.org/10.1109/GLOCOM.2014.7037516","url":null,"abstract":"The performance gain of cooperative communications depends heavily on the selection of relay. Most of existing relay selection methods aim at maximizing cooperative gain by selecting appropriate relay, without taking into account the adverse effect brought by cooperative communications: extra interferences introduced by relay transmission (called cooperation interference). Thus the derived performance gain could be inaccurate and/or the selected relay may be not optimal. In this paper, we address the assignment of relays for multiple communication sessions using cooperative communications in a wireless network. We first thoroughly investigate the adverse effect brought by using relays, and derive the cooperation gain with consideration of cooperation interference. Based on the insights of our investigation, we propose a method of assigning relays to individual transmission flows while taking into account cooperation interference in cooperative communications. In order to tradeoff the advantage and adverse effect caused by relay transmissions, we use an auction approach to address relay assignment of cooperative communications. Specifically, we propose a Single round double Auction Scheme (SAS) for centralized wireless network and a Multiple rounds sequential Auction Scheme (MAS) for decentralized wireless network for relay assignment. We conduct extensive simulation experiments to validate the effectiveness of SAS and MAS. The significance of the impact of cooperation interference, improvement of system throughput and energy efficiency are demonstrated by numerical results.","PeriodicalId":6492,"journal":{"name":"2014 IEEE Global Communications Conference","volume":"49 1","pages":"4496-4501"},"PeriodicalIF":0.0,"publicationDate":"2014-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76390697","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 : 2014-12-01DOI: 10.1109/GLOCOM.2014.7037229
D. Mazza, D. Tarchi, G. Corazza
The Smart cities applications are gaining an increasing interest among administrations, citizens and technologists for their suitability in managing the everyday life. One of the major challenges is regarding the possibility of managing in an efficient way the presence of multiple applications in a Wireless Heterogeneous Network (HetNet) environment, alongside the presence of a Mobile Cloud Computing (MCC) infrastructure. In this context we propose a utility function model derived from the economic world aiming to measure the Quality of Service (QoS), in order to choose the best access point in a HetNet to offload part of an application on the MCC, aiming to save energy for the Smart Mobile Devices (SMDs) and to reduce computational time. We distinguish three different types of application, considering different offloading percentage of computation and analyzing how the cell association algorithm allows energy saving and shortens computation time. The results show that when the network is overloaded, the proposed utility function allows to respect the target values by achieving higher throughput values, and reducing the energy consumption and the computational time.
{"title":"A user-satisfaction based offloading technique for smart city applications","authors":"D. Mazza, D. Tarchi, G. Corazza","doi":"10.1109/GLOCOM.2014.7037229","DOIUrl":"https://doi.org/10.1109/GLOCOM.2014.7037229","url":null,"abstract":"The Smart cities applications are gaining an increasing interest among administrations, citizens and technologists for their suitability in managing the everyday life. One of the major challenges is regarding the possibility of managing in an efficient way the presence of multiple applications in a Wireless Heterogeneous Network (HetNet) environment, alongside the presence of a Mobile Cloud Computing (MCC) infrastructure. In this context we propose a utility function model derived from the economic world aiming to measure the Quality of Service (QoS), in order to choose the best access point in a HetNet to offload part of an application on the MCC, aiming to save energy for the Smart Mobile Devices (SMDs) and to reduce computational time. We distinguish three different types of application, considering different offloading percentage of computation and analyzing how the cell association algorithm allows energy saving and shortens computation time. The results show that when the network is overloaded, the proposed utility function allows to respect the target values by achieving higher throughput values, and reducing the energy consumption and the computational time.","PeriodicalId":6492,"journal":{"name":"2014 IEEE Global Communications Conference","volume":"13 1","pages":"2783-2788"},"PeriodicalIF":0.0,"publicationDate":"2014-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87704692","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 : 2014-12-01DOI: 10.1109/GLOCOM.2014.7037261
Khaled Maaiuf Rabie, E. Alsusa
Power-line communication (PLC) is considered as the backbone of smart grid. Impulsive noise (IN) over such channels, however, remains the main factor responsible for degrading communication signals. A simple method to mitigate IN over PLC channels is to precede the receiver with a nonlinear preprocessor to blank and/or clip the incoming signal when it exceeds a certain threshold. Applying a combination of blanking and clipping in a hybrid fashion was shown to provide the best performance. The hybrid scheme is characterized by two thresholds T1 and T2 (T1 = α.T2), where a is a scaling factor. Previous studies assume a fixed value for the scaling factor and found that optimizing the threshold T2 is the key to enhance performance. In this paper, we show that the performance of this scheme is sensitive not only to the threshold, but also to the scaling factor. With this in mind, a mathematical expression for the output signal-to-noise ratio as a function of the threshold and scaling factor is formulated and used to optimize the hybrid scheme performance. Simulation results are also provided to validate our analysis. The results reveal that using an adaptive hybrid scheme with an optimally selected threshold and scaling factor always outperforms other nonlinear schemes.
{"title":"Threshold and scaling factor optimization for enhancing impulsive noise cancellation in PLC systems","authors":"Khaled Maaiuf Rabie, E. Alsusa","doi":"10.1109/GLOCOM.2014.7037261","DOIUrl":"https://doi.org/10.1109/GLOCOM.2014.7037261","url":null,"abstract":"Power-line communication (PLC) is considered as the backbone of smart grid. Impulsive noise (IN) over such channels, however, remains the main factor responsible for degrading communication signals. A simple method to mitigate IN over PLC channels is to precede the receiver with a nonlinear preprocessor to blank and/or clip the incoming signal when it exceeds a certain threshold. Applying a combination of blanking and clipping in a hybrid fashion was shown to provide the best performance. The hybrid scheme is characterized by two thresholds T1 and T2 (T1 = α.T2), where a is a scaling factor. Previous studies assume a fixed value for the scaling factor and found that optimizing the threshold T2 is the key to enhance performance. In this paper, we show that the performance of this scheme is sensitive not only to the threshold, but also to the scaling factor. With this in mind, a mathematical expression for the output signal-to-noise ratio as a function of the threshold and scaling factor is formulated and used to optimize the hybrid scheme performance. Simulation results are also provided to validate our analysis. The results reveal that using an adaptive hybrid scheme with an optimally selected threshold and scaling factor always outperforms other nonlinear schemes.","PeriodicalId":6492,"journal":{"name":"2014 IEEE Global Communications Conference","volume":"9 1","pages":"2977-2982"},"PeriodicalIF":0.0,"publicationDate":"2014-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87826853","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 : 2014-12-01DOI: 10.1109/GLOCOM.2014.7037280
Weijia Shi, Shaowei Wang, Dageng Chen
In this paper, we investigate the Energy Efficiency (EE) - Spectrum Efficiency (SE) tradeoff issue in an OFDM-based cognitive radio (CR) network. A multi-objective resource allocation problem is formulated, where we try to maximize the EE and the SE simultaneously. The Pareto optimal set of the formulated problem is characterized by analyzing the relationship between the EE and the SE. To find a unique globally optimal solution, we proposed a unified EE-SE tradeoff metric, based on which the original optimization task is transformed into a single-objective problem that has a D.C. (Difference of two Convex functions/sets) structure. Then an efficient barrier method is developed, where we speeds up the time-consuming computation of Newton step by exploiting the structure of the D.C. programming problem. Simulation results validate the effectiveness and efficiency of the proposed algorithm. Our general problem formulation sheds some insights on how to design an energy- and spectrum-efficient CR system.
本文研究了基于ofdm的认知无线电(CR)网络中能量效率(EE)和频谱效率(SE)的权衡问题。提出了一个多目标资源分配问题，其中我们试图同时最大化EE和SE。通过分析EE与SE之间的关系，确定了该问题的Pareto最优集。为了找到唯一的全局最优解，我们提出了一个统一的EE-SE权衡度量，在此基础上将原始优化任务转化为具有dc (two Convex functions/sets Difference of two Convex functions/sets)结构的单目标问题。然后，利用直流规划问题的结构，提出了一种有效的势垒法，加快了牛顿步的计算速度。仿真结果验证了该算法的有效性和高效性。我们的一般问题公式对如何设计能源和频谱高效的CR系统提供了一些见解。
{"title":"Energy- and spectrum-efficiency tradeoff in OFDM-based cognitive radio systems","authors":"Weijia Shi, Shaowei Wang, Dageng Chen","doi":"10.1109/GLOCOM.2014.7037280","DOIUrl":"https://doi.org/10.1109/GLOCOM.2014.7037280","url":null,"abstract":"In this paper, we investigate the Energy Efficiency (EE) - Spectrum Efficiency (SE) tradeoff issue in an OFDM-based cognitive radio (CR) network. A multi-objective resource allocation problem is formulated, where we try to maximize the EE and the SE simultaneously. The Pareto optimal set of the formulated problem is characterized by analyzing the relationship between the EE and the SE. To find a unique globally optimal solution, we proposed a unified EE-SE tradeoff metric, based on which the original optimization task is transformed into a single-objective problem that has a D.C. (Difference of two Convex functions/sets) structure. Then an efficient barrier method is developed, where we speeds up the time-consuming computation of Newton step by exploiting the structure of the D.C. programming problem. Simulation results validate the effectiveness and efficiency of the proposed algorithm. Our general problem formulation sheds some insights on how to design an energy- and spectrum-efficient CR system.","PeriodicalId":6492,"journal":{"name":"2014 IEEE Global Communications Conference","volume":"68 1","pages":"3092-3097"},"PeriodicalIF":0.0,"publicationDate":"2014-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87835584","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 : 2014-12-01DOI: 10.1109/GLOCOM.2014.7037421
Ziqi Yue, Qing Guo, W. Xiang
In this paper, we considered a practical system where the number of base station antennas serving tens users is large but finite. The signal must be collected before detection, and the optimal maximum a posteriori (MAP) detector has high computational complexity that grows exponentially with the number of users. Even the suboptimal MMSE-SIC (soft interference cancellation) requires complexity proportional to the cube of the number of the antenna units. In this paper, we proposed a distributed detection scheme done at each antenna unit separately, termed complex Gaussian belief propagation algorithm (CGaBP), for multicell multi-user detection. The multiuser detection problem is reduced to a sequence of scalar estimations, and detecting each individual user using CGaBP is asymptotically equivalent to detecting the same user through a scalar additive Gaussian channel with some degradation in the signal-to-noise ratio (SNR) of the desired user due to the collective impact of interfering users. The degradation is determined by the unique fixed-point of state evolution equations. Numerical results show that CGaBP has low complexity and overhead, and achieves optimal data estimates for Gaussian symbols, and is better than MMSE-SIC for finite-alphabet symbols.
{"title":"Complex Gaussian belief propagation algorithms for distributed multicell multiuser MIMO detection","authors":"Ziqi Yue, Qing Guo, W. Xiang","doi":"10.1109/GLOCOM.2014.7037421","DOIUrl":"https://doi.org/10.1109/GLOCOM.2014.7037421","url":null,"abstract":"In this paper, we considered a practical system where the number of base station antennas serving tens users is large but finite. The signal must be collected before detection, and the optimal maximum a posteriori (MAP) detector has high computational complexity that grows exponentially with the number of users. Even the suboptimal MMSE-SIC (soft interference cancellation) requires complexity proportional to the cube of the number of the antenna units. In this paper, we proposed a distributed detection scheme done at each antenna unit separately, termed complex Gaussian belief propagation algorithm (CGaBP), for multicell multi-user detection. The multiuser detection problem is reduced to a sequence of scalar estimations, and detecting each individual user using CGaBP is asymptotically equivalent to detecting the same user through a scalar additive Gaussian channel with some degradation in the signal-to-noise ratio (SNR) of the desired user due to the collective impact of interfering users. The degradation is determined by the unique fixed-point of state evolution equations. Numerical results show that CGaBP has low complexity and overhead, and achieves optimal data estimates for Gaussian symbols, and is better than MMSE-SIC for finite-alphabet symbols.","PeriodicalId":6492,"journal":{"name":"2014 IEEE Global Communications Conference","volume":"1 1","pages":"3928-3933"},"PeriodicalIF":0.0,"publicationDate":"2014-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86860096","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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