Pub Date : 2012-04-01DOI: 10.1109/WCNC.2012.6214388
R. Krishnan, M. Khanzadi, L. Svensson, T. Eriksson, T. Svensson
In this work, the problem of receiver design for phase noise estimation and data detection in the presence of oscillator phase noise in a point-to-point multiple-input multiple-output (MIMO) system is addressed. First, we discuss some interesting and challenging aspects in receiver design for MIMO systems in the presence of Wiener phase noise. Then, using the variational Bayesian (VB) framework, a joint iterative phase noise estimator and symbol detector are developed based on inverse Gibbs or variational free energy maximization. Further, the symbol error probability (SEP) of the newly proposed iterative scheme is compared with the optimal maximum likelihood (ML) detector with perfect phase information for 16-phase shift keying (PSK) and 16-quadrature amplitude modulation (QAM) schemes.
{"title":"Variational Bayesian framework for receiver design in the presence of phase noise in MIMO systems","authors":"R. Krishnan, M. Khanzadi, L. Svensson, T. Eriksson, T. Svensson","doi":"10.1109/WCNC.2012.6214388","DOIUrl":"https://doi.org/10.1109/WCNC.2012.6214388","url":null,"abstract":"In this work, the problem of receiver design for phase noise estimation and data detection in the presence of oscillator phase noise in a point-to-point multiple-input multiple-output (MIMO) system is addressed. First, we discuss some interesting and challenging aspects in receiver design for MIMO systems in the presence of Wiener phase noise. Then, using the variational Bayesian (VB) framework, a joint iterative phase noise estimator and symbol detector are developed based on inverse Gibbs or variational free energy maximization. Further, the symbol error probability (SEP) of the newly proposed iterative scheme is compared with the optimal maximum likelihood (ML) detector with perfect phase information for 16-phase shift keying (PSK) and 16-quadrature amplitude modulation (QAM) schemes.","PeriodicalId":329194,"journal":{"name":"2012 IEEE Wireless Communications and Networking Conference (WCNC)","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126729346","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 : 2012-04-01DOI: 10.1109/WCNC.2012.6214204
Chuyi Qian, Y. Ma, R. Tafazolli
Recently developed adaptive modulation schemes for opportunistic decode-and-forward (DF) relaying require knowledge of instantaneous channel-state-information (CSI) of all links. This paper aims at reducing signalling overhead of modulation-adaptive opportunistic DF relaying through exploitation of mixed channel knowledge. A novel semi-deterministic approach is proposed for performing joint rate-adaptation and best-relay selection. The selection process employs two criteria using mixed channel knowledge. A new metric namely the probability of missing the best relay (PMBR) is introduced, as only when the best relay is selected, the full diversity order can be achieved. It is shown that the proposed approach can achieve a good trade-off between the spectral efficiency and signalling overhead.
{"title":"Relay selection for modulation-adaptive opportunistic DF relaying using mixed channel knowledge","authors":"Chuyi Qian, Y. Ma, R. Tafazolli","doi":"10.1109/WCNC.2012.6214204","DOIUrl":"https://doi.org/10.1109/WCNC.2012.6214204","url":null,"abstract":"Recently developed adaptive modulation schemes for opportunistic decode-and-forward (DF) relaying require knowledge of instantaneous channel-state-information (CSI) of all links. This paper aims at reducing signalling overhead of modulation-adaptive opportunistic DF relaying through exploitation of mixed channel knowledge. A novel semi-deterministic approach is proposed for performing joint rate-adaptation and best-relay selection. The selection process employs two criteria using mixed channel knowledge. A new metric namely the probability of missing the best relay (PMBR) is introduced, as only when the best relay is selected, the full diversity order can be achieved. It is shown that the proposed approach can achieve a good trade-off between the spectral efficiency and signalling overhead.","PeriodicalId":329194,"journal":{"name":"2012 IEEE Wireless Communications and Networking Conference (WCNC)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126962797","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 : 2012-04-01DOI: 10.1109/WCNC.2012.6214444
Guanghui Li, Xin Zhang, Sheng Lei, Cong Xiong, Dacheng Yang
The fixed-complexity sphere decoder (FSD) has been proposed to attain the near-optimal performance achieving the same diversity order as the maximum-likelihood decoder (MLD) recently. However, it suffers great redundant computations resulting in high power consumption. In this paper, we conduct an improved algorithm for the original FSD by using early termination (ET). This algorithm (abbreviated as ET-FSD) preserves the advantages of sphere decoder (SD) such as branch pruning and an adaptively updated pruning threshold. We compare the ET-FSD with the original FSD and a lately developed statistical threshold-based FSD (ST-FSD). Simulation results demonstrate that the ET-FSD attains the same performance with a much lower cost than the FSD, and is much more efficient than the ST-FSD in practice. In addition, the statistical threshold-based method can also be used for the ET-FSD (i.e., ST-ET-FSD) to further reduce the complexity.
{"title":"An early termination-based improved algorithm for fixed-complexity sphere decoder","authors":"Guanghui Li, Xin Zhang, Sheng Lei, Cong Xiong, Dacheng Yang","doi":"10.1109/WCNC.2012.6214444","DOIUrl":"https://doi.org/10.1109/WCNC.2012.6214444","url":null,"abstract":"The fixed-complexity sphere decoder (FSD) has been proposed to attain the near-optimal performance achieving the same diversity order as the maximum-likelihood decoder (MLD) recently. However, it suffers great redundant computations resulting in high power consumption. In this paper, we conduct an improved algorithm for the original FSD by using early termination (ET). This algorithm (abbreviated as ET-FSD) preserves the advantages of sphere decoder (SD) such as branch pruning and an adaptively updated pruning threshold. We compare the ET-FSD with the original FSD and a lately developed statistical threshold-based FSD (ST-FSD). Simulation results demonstrate that the ET-FSD attains the same performance with a much lower cost than the FSD, and is much more efficient than the ST-FSD in practice. In addition, the statistical threshold-based method can also be used for the ET-FSD (i.e., ST-ET-FSD) to further reduce the complexity.","PeriodicalId":329194,"journal":{"name":"2012 IEEE Wireless Communications and Networking Conference (WCNC)","volume":"217 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116160570","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 : 2012-04-01DOI: 10.1109/WCNC.2012.6214179
Yongsheng Liu, Jie Li, M. Guizani
Time synchronization is crucial to Wireless Sensor Networks (WSNs) due to the requirement of coordination between sensor nodes. Existing secure time synchronization protocols of WSNs introduce high overhead when used for global time synchronization. In this paper, we propose a lightweight secure global time synchronization protocol for WSNs. In the proposed protocol, a broadcast synchronization packet makes all sensor nodes in the network synchronize with the trusted source. The synchronization packet is protected by a proposed broadcast authentication algorithm, which introduces asymmetry by transmitting hash values of secret keys in advance. It achieves immediate authentication and does not require the loose time synchronization. To defend the pulse-delay attacks, the arrival time of the synchronization packet is checked according to the estimated arrival time interval. The upper bound on the skew of the proposed protocol is proved. The message complexity in one period of the proposed protocol is O(n) where n represents the number of sensor nodes. The simulation results show that the maximum skew is within tens of milliseconds.
{"title":"Lightweight secure global time synchronization for Wireless Sensor Networks","authors":"Yongsheng Liu, Jie Li, M. Guizani","doi":"10.1109/WCNC.2012.6214179","DOIUrl":"https://doi.org/10.1109/WCNC.2012.6214179","url":null,"abstract":"Time synchronization is crucial to Wireless Sensor Networks (WSNs) due to the requirement of coordination between sensor nodes. Existing secure time synchronization protocols of WSNs introduce high overhead when used for global time synchronization. In this paper, we propose a lightweight secure global time synchronization protocol for WSNs. In the proposed protocol, a broadcast synchronization packet makes all sensor nodes in the network synchronize with the trusted source. The synchronization packet is protected by a proposed broadcast authentication algorithm, which introduces asymmetry by transmitting hash values of secret keys in advance. It achieves immediate authentication and does not require the loose time synchronization. To defend the pulse-delay attacks, the arrival time of the synchronization packet is checked according to the estimated arrival time interval. The upper bound on the skew of the proposed protocol is proved. The message complexity in one period of the proposed protocol is O(n) where n represents the number of sensor nodes. The simulation results show that the maximum skew is within tens of milliseconds.","PeriodicalId":329194,"journal":{"name":"2012 IEEE Wireless Communications and Networking Conference (WCNC)","volume":"80 6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116527785","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 : 2012-04-01DOI: 10.1109/WCNC.2012.6214001
Hyeonje Cho, G. Hwang
We consider a time slotted cognitive radio (CR) network under Rayleigh fading where multiple secondary users (SUs) contend for spectrum usage over available primary users' channels. In the contention, all SUs use common access probabilities to decide whether they access one of available channels. We focus on the throughput performance of an arbitrary SU. To improve the throughput performance of SUs, it is desirable that the access probabilities are adapted to the information on channel status and fading condition. In the analysis, we derive the optimal access probabilities that maximize the throughput performance of an arbitrary SU. From our analysis, we provide an insight on how to obtain optimal access probabilities in the CR network. We also investigate the effect of the knowledge of channel status and fading condition on throughput performance. Numerical results are provided to investigate throughput performance behavior.
{"title":"Throughput performance optimization in cognitive radio networks under Rayleigh fading","authors":"Hyeonje Cho, G. Hwang","doi":"10.1109/WCNC.2012.6214001","DOIUrl":"https://doi.org/10.1109/WCNC.2012.6214001","url":null,"abstract":"We consider a time slotted cognitive radio (CR) network under Rayleigh fading where multiple secondary users (SUs) contend for spectrum usage over available primary users' channels. In the contention, all SUs use common access probabilities to decide whether they access one of available channels. We focus on the throughput performance of an arbitrary SU. To improve the throughput performance of SUs, it is desirable that the access probabilities are adapted to the information on channel status and fading condition. In the analysis, we derive the optimal access probabilities that maximize the throughput performance of an arbitrary SU. From our analysis, we provide an insight on how to obtain optimal access probabilities in the CR network. We also investigate the effect of the knowledge of channel status and fading condition on throughput performance. Numerical results are provided to investigate throughput performance behavior.","PeriodicalId":329194,"journal":{"name":"2012 IEEE Wireless Communications and Networking Conference (WCNC)","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114298907","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 : 2012-04-01DOI: 10.1109/WCNC.2012.6213930
A. Chelli, M. Pätzold
For time-invariant frequency-selective channels, the transfer function is a superposition of waves having different propagation delays and path gains. In order to estimate the frequency correlation function (FCF) of such channels, the frequency averaging technique can be utilized. The obtained FCF can be expressed as a sum of auto-terms (ATs) and cross-terms (CTs). The ATs are caused by the autocorrelation of individual path components. The CTs are due to the cross-correlation of different path components. These CTs have no physical meaning and leads to an estimation error. We propose a new estimation method aiming to improve the estimation accuracy of the FCF of a band-limited transfer function. The basic idea behind the proposed method is to introduce a kernel function aiming to reduce the CT effect, while preserving the ATs. In this way, we can improve the estimation of the FCF. The performance of the proposed method and the frequency averaging technique is analyzed using a synthetically generated transfer function. We show that the proposed method is more accurate than the frequency averaging technique. The accurate estimation of the FCF is crucial for the system design. In fact, we can determine the coherence bandwidth from the FCF. The exact knowledge of the coherence bandwidth is beneficial in both the design as well as optimization of frequency interleaving and pilot arrangement schemes.
{"title":"An improved method for estimating the frequency correlation function","authors":"A. Chelli, M. Pätzold","doi":"10.1109/WCNC.2012.6213930","DOIUrl":"https://doi.org/10.1109/WCNC.2012.6213930","url":null,"abstract":"For time-invariant frequency-selective channels, the transfer function is a superposition of waves having different propagation delays and path gains. In order to estimate the frequency correlation function (FCF) of such channels, the frequency averaging technique can be utilized. The obtained FCF can be expressed as a sum of auto-terms (ATs) and cross-terms (CTs). The ATs are caused by the autocorrelation of individual path components. The CTs are due to the cross-correlation of different path components. These CTs have no physical meaning and leads to an estimation error. We propose a new estimation method aiming to improve the estimation accuracy of the FCF of a band-limited transfer function. The basic idea behind the proposed method is to introduce a kernel function aiming to reduce the CT effect, while preserving the ATs. In this way, we can improve the estimation of the FCF. The performance of the proposed method and the frequency averaging technique is analyzed using a synthetically generated transfer function. We show that the proposed method is more accurate than the frequency averaging technique. The accurate estimation of the FCF is crucial for the system design. In fact, we can determine the coherence bandwidth from the FCF. The exact knowledge of the coherence bandwidth is beneficial in both the design as well as optimization of frequency interleaving and pilot arrangement schemes.","PeriodicalId":329194,"journal":{"name":"2012 IEEE Wireless Communications and Networking Conference (WCNC)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114391317","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 : 2012-04-01DOI: 10.1109/WCNC.2012.6213964
A. Zalonis, N. Dimitriou, A. Polydoros, J. Nasreddine, P. Mähönen
The paper investigates the use of Radio Environment Maps (REMs) as a tool for Interference Management (IM) in two-tier cellular networks comprising macro- and femto-cells. The REMs are databases that provide, through different instances distributed over network elements, a variety of network- and user-related context information for improving IM and Radio Resource Management (RRM) procedures. In this context, the focus in this paper is to present the benefit of using REM information on practical power control schemes for the Femtocell downlink transmission in co-channel two-tier deployment.
{"title":"Femtocell downlink power control based on Radio Environment Maps","authors":"A. Zalonis, N. Dimitriou, A. Polydoros, J. Nasreddine, P. Mähönen","doi":"10.1109/WCNC.2012.6213964","DOIUrl":"https://doi.org/10.1109/WCNC.2012.6213964","url":null,"abstract":"The paper investigates the use of Radio Environment Maps (REMs) as a tool for Interference Management (IM) in two-tier cellular networks comprising macro- and femto-cells. The REMs are databases that provide, through different instances distributed over network elements, a variety of network- and user-related context information for improving IM and Radio Resource Management (RRM) procedures. In this context, the focus in this paper is to present the benefit of using REM information on practical power control schemes for the Femtocell downlink transmission in co-channel two-tier deployment.","PeriodicalId":329194,"journal":{"name":"2012 IEEE Wireless Communications and Networking Conference (WCNC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129820716","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 : 2012-04-01DOI: 10.1109/WCNC.2012.6213982
Mohammad Fathi, E. Karipidis
We consider the joint allocation of receiver, bit, and power to subcarriers in the downlink of multicell orthogonal frequency-division multiple-access (OFDMA) networks. Assuming that the cells share the entire bandwidth and that the rates are discrete, we formulate the joint allocation problem as a nonlinear mixed integer program (MIP), which however has exponential worst-case complexity. We capitalize on the capability of the receivers to measure the interference-plus-noise on every subcarrier and decompose the joint problem into a set of smaller-scale linear MIPs solved by individual base stations. Accordingly, we propose a distributed algorithm with linear complexity, in which the base stations participate in the problem solution in a round-robin manner. Simulation results demonstrate the effectiveness of the proposed algorithm in comparison with the iterative waterfilling algorithm and the successive optimal solution, by means of standard branch-and-cut solvers, of the individual MIPs.
{"title":"Distributed resource optimization in multicell OFDMA networks","authors":"Mohammad Fathi, E. Karipidis","doi":"10.1109/WCNC.2012.6213982","DOIUrl":"https://doi.org/10.1109/WCNC.2012.6213982","url":null,"abstract":"We consider the joint allocation of receiver, bit, and power to subcarriers in the downlink of multicell orthogonal frequency-division multiple-access (OFDMA) networks. Assuming that the cells share the entire bandwidth and that the rates are discrete, we formulate the joint allocation problem as a nonlinear mixed integer program (MIP), which however has exponential worst-case complexity. We capitalize on the capability of the receivers to measure the interference-plus-noise on every subcarrier and decompose the joint problem into a set of smaller-scale linear MIPs solved by individual base stations. Accordingly, we propose a distributed algorithm with linear complexity, in which the base stations participate in the problem solution in a round-robin manner. Simulation results demonstrate the effectiveness of the proposed algorithm in comparison with the iterative waterfilling algorithm and the successive optimal solution, by means of standard branch-and-cut solvers, of the individual MIPs.","PeriodicalId":329194,"journal":{"name":"2012 IEEE Wireless Communications and Networking Conference (WCNC)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129958526","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 : 2012-04-01DOI: 10.1109/WCNC.2012.6214324
Halil Yetgin, Kent Tsz Kan Cheung, L. Hanzo
Wireless ad hoc networks suffer from several limitations, such as routing failures, potentially excessive bandwidth requirements, computational constraints and limited storage capability. Their routing strategy plays a significant role in determining the overall performance of the multi-hop network. However, in conventional network design only one of the desired routing-related objectives is optimized, while other objectives are typically assumed to be the constraints imposed on the problem. In this paper, we invoke the Non-dominated Sorting based Genetic Algorithm-II (NSGA-II) and the MultiObjective Differential Evolution (MODE) algorithm for finding optimal routes from a given source to a given destination in the face of conflicting design objectives, such as the dissipated energy and the end-to-end delay in a fully-connected arbitrary multi-hop network. Our simulation results show that both the NSGA-II and MODE algorithms are efficient in solving these routing problems and are capable of finding the Pareto-optimal solutions at lower complexity than the `brute-force' exhaustive search, when the number of nodes is higher than or equal to 10. Additionally, we demonstrate that at the same complexity, the MODE algorithm is capable of finding solutions closer to the Pareto front and typically, converges faster than the NSGA-II algorithm.
无线自组织网络受到一些限制，例如路由故障、潜在的过多带宽需求、计算限制和有限的存储能力。它们的路由策略在决定多跳网络的整体性能方面起着重要的作用。然而，在传统的网络设计中，只有一个期望的路由相关目标是优化的，而其他目标通常被认为是强加在问题上的约束。在本文中，我们调用基于非支配排序的遗传算法- ii (NSGA-II)和多目标差分进化(MODE)算法来寻找从给定源到给定目的地的最优路由，面对冲突的设计目标，例如在全连接任意多跳网络中耗散能量和端到端延迟。仿真结果表明，当节点数大于或等于10时，NSGA-II和MODE算法都能有效地解决这些路由问题，并且能够以比“暴力破解”穷举搜索更低的复杂度找到帕累托最优解。此外，我们证明了在相同的复杂度下，MODE算法能够找到更接近Pareto前沿的解，并且通常比NSGA-II算法收敛得更快。
{"title":"Multi-objective routing optimization using evolutionary algorithms","authors":"Halil Yetgin, Kent Tsz Kan Cheung, L. Hanzo","doi":"10.1109/WCNC.2012.6214324","DOIUrl":"https://doi.org/10.1109/WCNC.2012.6214324","url":null,"abstract":"Wireless ad hoc networks suffer from several limitations, such as routing failures, potentially excessive bandwidth requirements, computational constraints and limited storage capability. Their routing strategy plays a significant role in determining the overall performance of the multi-hop network. However, in conventional network design only one of the desired routing-related objectives is optimized, while other objectives are typically assumed to be the constraints imposed on the problem. In this paper, we invoke the Non-dominated Sorting based Genetic Algorithm-II (NSGA-II) and the MultiObjective Differential Evolution (MODE) algorithm for finding optimal routes from a given source to a given destination in the face of conflicting design objectives, such as the dissipated energy and the end-to-end delay in a fully-connected arbitrary multi-hop network. Our simulation results show that both the NSGA-II and MODE algorithms are efficient in solving these routing problems and are capable of finding the Pareto-optimal solutions at lower complexity than the `brute-force' exhaustive search, when the number of nodes is higher than or equal to 10. Additionally, we demonstrate that at the same complexity, the MODE algorithm is capable of finding solutions closer to the Pareto front and typically, converges faster than the NSGA-II algorithm.","PeriodicalId":329194,"journal":{"name":"2012 IEEE Wireless Communications and Networking Conference (WCNC)","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128347326","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 : 2012-04-01DOI: 10.1109/WCNC.2012.6214021
Jiyoung Cha, Hu Jin, B. Jung, D. Sung
IEEE 802.11ac standard has newly adopted a downlink multi-user multiple-input and multiple-output (DL-MU-MIMO) scheme. For user multiplexing in downlink WLAN, we can also use a frame aggregation scheme for multiplexing multiple users' data with space-time block coding (STBC) for achieving spatial diversity. We compare the performance of the two downlink user multiplexing schemes: multi-user MIMO and frame aggregation in IEEE 802.11ac. If each user's encoded data stream has a similar length, the multi-user MIMO scheme yields better average throughput than the frame aggregation scheme. On the other hand, if each user's encoded data stream has a different length, the frame aggregation scheme outperforms the multi-user MIMO scheme in terms of average throughput. In a fast-varying channel, the multi-user MIMO scheme yields worse throughput due to the channel feedback overhead, compared to that with the frame aggregation scheme. We also observe that the multi-user frame aggregation scheme with STBC always outperforms a single-user transmission scheme with STBC in terms of average throughput due to enhanced MAC layer efficiency through frame aggregation.
{"title":"Performance comparison of downlink user multiplexing schemes in IEEE 802.11ac: Multi-user MIMO vs. frame aggregation","authors":"Jiyoung Cha, Hu Jin, B. Jung, D. Sung","doi":"10.1109/WCNC.2012.6214021","DOIUrl":"https://doi.org/10.1109/WCNC.2012.6214021","url":null,"abstract":"IEEE 802.11ac standard has newly adopted a downlink multi-user multiple-input and multiple-output (DL-MU-MIMO) scheme. For user multiplexing in downlink WLAN, we can also use a frame aggregation scheme for multiplexing multiple users' data with space-time block coding (STBC) for achieving spatial diversity. We compare the performance of the two downlink user multiplexing schemes: multi-user MIMO and frame aggregation in IEEE 802.11ac. If each user's encoded data stream has a similar length, the multi-user MIMO scheme yields better average throughput than the frame aggregation scheme. On the other hand, if each user's encoded data stream has a different length, the frame aggregation scheme outperforms the multi-user MIMO scheme in terms of average throughput. In a fast-varying channel, the multi-user MIMO scheme yields worse throughput due to the channel feedback overhead, compared to that with the frame aggregation scheme. We also observe that the multi-user frame aggregation scheme with STBC always outperforms a single-user transmission scheme with STBC in terms of average throughput due to enhanced MAC layer efficiency through frame aggregation.","PeriodicalId":329194,"journal":{"name":"2012 IEEE Wireless Communications and Networking Conference (WCNC)","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128369968","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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