European Transactions on Telecommunications最新文献_第9页

Joint EM channel and covariance estimation with sufficient-statistic chip combining for a SIMO MC-CDMA anti-jam system SIMO MC-CDMA抗干扰系统的联合电磁信道和充分统计芯片组合的协方差估计

European Transactions on Telecommunications Pub Date : 2010-06-18 DOI: 10.1002/ett.1425

M. Asadullah, Gordon L. Stüber

{"title":"Joint EM channel and covariance estimation with sufficient-statistic chip combining for a SIMO MC-CDMA anti-jam system","authors":"M. Asadullah, Gordon L. Stüber","doi":"10.1002/ett.1425","DOIUrl":"https://doi.org/10.1002/ett.1425","url":null,"abstract":"Joint iterative channel and covariance estimation with sufficient-statistic-based chip combining is studied for the downlink of a multicarrier code division multiple access (MC-CDMA) system operating under partial-band noise jamming (PBNJ). To estimate the channel and AWGN-plus-PBNJ covariance, we apply the expectation-maximisation (EM) algorithm which exploits the log-likelihood ratio (LLR) from the decoder. The proposed chip combiner guarantees no loss of information in the soft output generated by the demapper. In our approach, the channel estimator or the chip combiner only requires the AWGN-plus-PBNJ power of each subcarrier to suppress jamming. Therefore, significant complexity reduction is achieved because the receiver does not need to estimate the jammer state information (JSI) and individual variances of the AWGN and PBNJ on each subcarrier for chip combining. Simulation results show that the sufficient-statistic chip combiner always offers a smaller bit error rate (BER) than the minimum mean square error (MMSE) chip combiner provided that reliable estimates of the channel impulse response and noise-plus-jamming covariance are available. Copyright © 2010 John Wiley & Sons, Ltd.","PeriodicalId":50473,"journal":{"name":"European Transactions on Telecommunications","volume":"170 1","pages":"409-416"},"PeriodicalIF":0.0,"publicationDate":"2010-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84004519","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}

引用次数: 0

PAPR reduction technique using pilot symbols for OFDM systems OFDM系统中使用导频符号的PAPR降低技术

European Transactions on Telecommunications Pub Date : 2010-06-18 DOI: 10.1002/ETT.1423

I. M. Mahafeno, Y. Louët, J. Hélard, Y. Nasser, A. Ho

引用次数: 6

Comparison of different channel estimation approaches for Block-IFDMA Block-IFDMA不同信道估计方法的比较

European Transactions on Telecommunications Pub Date : 2010-06-08 DOI: 10.1002/ett.1427

Anja Sohl, A. Klein

{"title":"Comparison of different channel estimation approaches for Block-IFDMA","authors":"Anja Sohl, A. Klein","doi":"10.1002/ett.1427","DOIUrl":"https://doi.org/10.1002/ett.1427","url":null,"abstract":"SUMMARY In this paper, channel estimation for Discrete Fourier Transform (DFT) precoded Orthogonal Frequency Division Multiple Access (OFDMA) with block-interleaved subcarrier allocation per user, which is denoted as Block-Interleaved Frequency Division Multiple Access (B-IFDMA), is considered. Recent investigations are presented for new pilot insertion methods which exhibit different impact on the Peak-to-Average Power Ratio (PAPR) of the transmit signal and offer different possibilities of positioning the pilots in frequency domain. Each of these pilot insertion methods is combined with a corresponding algorithm to estimate the Channel Variations in Frequency Domain (CVFD). The Channel Variations in Time Domain (CVTD) are estimated by an improved Decision Directed Channel Estimation (DDCE) with joint iterative Wiener filtering which reduces the error propagation by considering certain neighbouring symbols jointly in each iteration step. The DDCE is compared to a Wiener interpolation filter for the estimation of CVTD. The combinations of pilot insertion method, estimation algorithm for CVFD and CVTD are compared in terms of the PAPR and the Mean Square Error (MSE) performance. Thereby, the impact of different pilot positions in frequency domain and time domain is investigated. Copyright © 2010 John Wiley & Sons, Ltd.","PeriodicalId":50473,"journal":{"name":"European Transactions on Telecommunications","volume":"38 1","pages":"417-425"},"PeriodicalIF":0.0,"publicationDate":"2010-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81244052","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}

引用次数: 1

Communication Networks Survivable routing algorithm with mixed shared protection in fault-tolerant GMPLS multi-layered optical networks 容错GMPLS多层光网络中混合共享保护的通信网络生存性路由算法

European Transactions on Telecommunications Pub Date : 2010-06-01 DOI: 10.1002/ETT.1409

Lei Guo, Jiannong Cao, Xingwei Wang, Xuetao Wei, Qiming Gai, Zhaolong Ning, Cunqian Yu

{"title":"Communication Networks Survivable routing algorithm with mixed shared protection in fault-tolerant GMPLS multi-layered optical networks","authors":"Lei Guo, Jiannong Cao, Xingwei Wang, Xuetao Wei, Qiming Gai, Zhaolong Ning, Cunqian Yu","doi":"10.1002/ETT.1409","DOIUrl":"https://doi.org/10.1002/ETT.1409","url":null,"abstract":"In this paper, we studied survivability in general multi-protocol label switching (GMPLS) multi-layered optical networks and proposed a novel mixed shared protection algorithm (MSPA) based on the integrated layered graph (ILG) to tolerate single-fibre link failure. The ILG is composed of one virtual topology layer (VTL), corresponding to IP/MPLS layer; multiple wavelength-plane layers (WPLs), corresponding to the wavelength-division multiplexing (WDM) optical layer; and some virtual links that connect the VTL to each WPL in order to solve the problem on routing, wavelength assignment and low-speed traffic grooming. For every connection request, the MSPA first computes a single-hop or multi-hop label switching path (LSP) pair, involving a working LSP and a physical link-disjoint backup LSP in the VTL. If the LSP pair is not found in the VTL, the MSPA computes the new LSP pair in the WPL. Conversely, if the new LSP pair is not detected in the WPL, the MSPA computes the hybrid multi-hop LSP pair in the ILG. In the MSPA, if the two working LSPs are in physical link-disjoint, their corresponding backup LSPs can share the backup bandwidth. In addition, the working LSPs and the backup LSPs can also share the same mixed of wavelength, in which the different bandwidths can be assigned to different working and backup LSPs. Simulation results show that, compared to previous algorithm, the MSPA can obtain a better bandwidth utilisation ratio (BUR) with a lower blocking probability. Copyright © 2010 John Wiley & Sons, Ltd.","PeriodicalId":50473,"journal":{"name":"European Transactions on Telecommunications","volume":"76 1","pages":"312-323"},"PeriodicalIF":0.0,"publicationDate":"2010-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83861638","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}

引用次数: 4

Information Theory Capacity of the two-way relay channel within a constant gap 信息论在一定间隙内双向中继信道的容量

European Transactions on Telecommunications Pub Date : 2010-06-01 DOI: 10.1002/ett.1399

A. Avestimehr, A. Sezgin, David Tse

引用次数: 96

Communication Theory Transforming the distribution of OFDM signals for peak-to-average power ratio reduction 通信理论变换OFDM信号的分布以降低峰均功率比

European Transactions on Telecommunications Pub Date : 2010-06-01 DOI: 10.1002/ett.1395

Xiaodong Zhu, Guangxi Zhu, Pei Lin

引用次数: 15

Communication Networks Opportunistic multiuser scheduling with reduced feedback load 通信网络减少反馈负载的机会多用户调度

European Transactions on Telecommunications Pub Date : 2010-06-01 DOI: 10.1002/ett.1403

Y. Al-Harthi

引用次数: 6

Wireless Systems A simplified MAP channel estimator for OFDM systems under Rayleigh fading 无线系统瑞利衰落下OFDM系统的一种简化MAP信道估计器

European Transactions on Telecommunications Pub Date : 2010-06-01 DOI: 10.1002/ett.1415

Selva Muratoğlu Çürük, Y. Tanik

{"title":"Wireless Systems A simplified MAP channel estimator for OFDM systems under Rayleigh fading","authors":"Selva Muratoğlu Çürük, Y. Tanik","doi":"10.1002/ett.1415","DOIUrl":"https://doi.org/10.1002/ett.1415","url":null,"abstract":"This paper presents a simplified Maximum A Posteriori (SMAP) channel estimator to be used in orthogonal frequency division multiplexing (OFDM) systems under the Rayleigh fading assumption for the subchannels, using a parametric correlation model and assuming that the channel is frequency selective and slowly time varying. Expressions for the mean-square error (MSE) of estimations are derived to evaluate the performance of the estimator. The relation between the correlation of subchannels taps and error variance is investigated. Dependencies of the proposed estimator's performance on the correlation parameter estimation error and signal-to-noise ratios (SNR) estimation error are analysed. We provide approximations on the estimator algorithms in order to make the estimator practical. The simulations done using measured channel data show that the proposed estimator with approximations operates satisfactorily with negligible loss in performance. Finally, we investigate the symbol error rate (SER) performance of an OFDM system using quadrature phase-shift keying (QPSK) modulation, based on channel estimation modes (a) training sequence (b) decision feedback and (c) pilot subcarriers. The results have indicated that the proposed estimator performance is always better than maximum likelihood (ML) estimator, and as the subchannel correlation increases (large number of subcarriers) the performance comes very close to that of exactly known channel case. Copyright © 2010 John Wiley & Sons, Ltd.","PeriodicalId":50473,"journal":{"name":"European Transactions on Telecommunications","volume":"52 1","pages":"396-405"},"PeriodicalIF":0.0,"publicationDate":"2010-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73622058","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}

引用次数: 5

Mobile Networks Trust management in wireless sensor networks 无线传感器网络中的信任管理

European Transactions on Telecommunications Pub Date : 2010-06-01 DOI: 10.1002/ett.1413

T. Zahariadis, H. Leligou, P. Trakadas, S. Voliotis

{"title":"Mobile Networks Trust management in wireless sensor networks","authors":"T. Zahariadis, H. Leligou, P. Trakadas, S. Voliotis","doi":"10.1002/ett.1413","DOIUrl":"https://doi.org/10.1002/ett.1413","url":null,"abstract":"SUMMARY The range of applications of wireless sensor networks is so wide that it tends to invade our every day life. In the future, a sensor network will survey our health, our home, the roads we follow, the office or the industry we work in or even the aircrafts we use, in an attempt to enhance our safety. However, the wireless sensor networks themselves are prone to security attacks. The list of security attacks, although already very long, continues to augment impeding the expansion of these networks. The trust management schemes consist of a powerful tool for the detection of unexpected node behaviours (either faulty or malicious). Once misbehaving nodes are detected, their neighbours can use this information to avoid cooperating with them, either for data forwarding, data aggregation or any other cooperative function. A variety of trust models which follow different directions regarding the distribution of measurement functionality, the monitored behaviours and the way measurements are used to calculate/define the node’s trustworthiness has been presented in the literature. In this paper, we survey trust models in an attempt to explore the interplay among the implementation requirements, the resource consumption and the achieved security. Our goal is to draw guidelines for the design of deployable trust model designs with respect to the available node and network capabilities and application peculiarities. Copyright © 2010 John Wiley & Sons, Ltd.","PeriodicalId":50473,"journal":{"name":"European Transactions on Telecommunications","volume":"49 1","pages":"386-395"},"PeriodicalIF":0.0,"publicationDate":"2010-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89980020","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}

引用次数: 114

Selective mapping for reduced complexity turbo channel estimation operating on highly time and frequency selective channels 选择性映射降低复杂性涡轮信道估计操作在高时间和频率选择性信道

European Transactions on Telecommunications Pub Date : 2010-04-08 DOI: 10.1002/ett.1397

Sihem Châabouni, M. Siala, N. Sellami

引用次数: 0