Int. J. Wirel. Opt. Commun.最新文献

Design and Analysis of Quad-Band Wilkinson Power Divider 四频带威尔金森功率分配器的设计与分析

Int. J. Wirel. Opt. Commun. Pub Date : 2007-09-01 DOI: 10.1142/S0219799507000680

Hussam Jwaied, Firas Muwanes, N. Dib

引用次数: 10

Ultra-Wideband Multi-Band OFDM Systems: Timing Synchronization and Frequency Offset Estimation 超宽带多频带OFDM系统:定时同步和频率偏移估计

Int. J. Wirel. Opt. Commun. Pub Date : 2007-09-01 DOI: 10.1142/S0219799507000722

Chin Wee Yak, Z. Lei

{"title":"Ultra-Wideband Multi-Band OFDM Systems: Timing Synchronization and Frequency Offset Estimation","authors":"Chin Wee Yak, Z. Lei","doi":"10.1142/S0219799507000722","DOIUrl":"https://doi.org/10.1142/S0219799507000722","url":null,"abstract":"In digital communications systems, receiver synchronization (in terms of timing and carrier frequency offset estimation) is fundamental before accurate channel estimation can follow. Timing errors can cause intersymbol interferences (ISI) that destroy OFDM subcarriers' orthogonality and degrade system performance [Athaudage, 2002; Speth et al., 1997]. On the other hand, frequency offset (FO) may arise from random Doppler frequency shifts, carrier frequency mismatch between transmitter and receiver oscillators and sampling frequency errors. The FO causes severe reduction in signal amplitude and introduces intercarrier interferences (ICI) which cause severe bit error rate (BER) degradation [Moose, 1994]. It is hence critical to accurately estimate the timing and FO for reliable communications. For ultra-wideband (UWB) multi-band OFDM systems, the proposed algorithm, First significant multipath detection via Threshold comparison of Adjacent samples (FTA), focuses on detecting the first significant multipath component (MPC) by comparing the difference between two adjacent energy samples of a proposed metric against a pre-defined threshold. Each energy sample is obtained from summing received multipath components' energies. A simplified FO estimator is obtained from the proposed metric by averaging the phase differences between each corresponding subcarrier of the two identical adjacent training symbols. Using timing information, the maximum likelihood (ML) FO estimator and its theoretical Cramer Rao Bound (CRB) for the MB-OFDM UWB system are derived for comparison with FTA.","PeriodicalId":185917,"journal":{"name":"Int. J. Wirel. Opt. Commun.","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124837017","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

Scalable Lifetime in Mobile Ad Hoc Networks 移动Ad Hoc网络的可扩展生存期

Int. J. Wirel. Opt. Commun. Pub Date : 2007-09-01 DOI: 10.1142/S0219799507000709

A. Marowka

{"title":"Scalable Lifetime in Mobile Ad Hoc Networks","authors":"A. Marowka","doi":"10.1142/S0219799507000709","DOIUrl":"https://doi.org/10.1142/S0219799507000709","url":null,"abstract":"Wireless ad hoc networks are self-organized groups of mobile devices that are able to communicate with each other using a wireless physical medium. A critical issue in ad hoc networks is how to maintain network activities in order to achieve maximum lifespan despite energy constraints. The aim of power management of routing protocols is to prolong the lifetime of the entire network and to increase the delivery rate of transactions carried out through the mobile network. We define a Quality-of-Power-Service (QoPS) metric to evaluate the efficiency of power-aware unicast routing protocols. The aim of these protocols is to increase the longevity of ad hoc networks. QoPS metric is applied to different position-based power-aware unicast routing protocols. Our simulation results confirm that power-relative distribution of data streams in multi-path unicast routing protocols distributes energy consumption to multiple nodes and thus increase the network's lifetime. Moreover, the experiments show that multi-path protocols provide excellent scalability and high delivery success rate. The locality distribution phenomenon discovered by the simulations explains, on the one hand, the improved scalability and the long lifetime of large, dense, and high-degree wireless networks, and on the other hand, the short lifetime of small, sparse, and low-degree networks.","PeriodicalId":185917,"journal":{"name":"Int. J. Wirel. Opt. Commun.","volume":"276 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131537065","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

Optimized Quality of Service (QoS) Routing in Mobile Adhoc Networks Using Self-Healing Techniques 基于自修复技术的移动自组织网络中优化服务质量(QoS)路由

Int. J. Wirel. Opt. Commun. Pub Date : 2007-09-01 DOI: 10.1142/S0219799507000679

R. Asokan, A. Natarajan, C. Venkatesh

引用次数: 4

Minimized Memory Architecture for Low Latency Viterbi Decoder Using Zig-Zag Algorithm 基于z - zag算法的低延迟Viterbi译码器的最小化内存结构

Int. J. Wirel. Opt. Commun. Pub Date : 2007-09-01 DOI: 10.1142/S0219799507000667

C. Arun, V. Rajamani

引用次数: 2

Combined Method for Adaptive Channel Estimation with Application to DMT Systems 自适应信道估计组合方法及其在DMT系统中的应用

Int. J. Wirel. Opt. Commun. Pub Date : 2007-09-01 DOI: 10.1142/S0219799507000655

Ahmad Al Amayreh, J. Masson, M. Hélard

引用次数: 2

Wavelength Selective Auxiliary C-Band ASE Pumping for L-Band EDFA l波段EDFA的波长选择性辅助c波段ASE泵浦

Int. J. Wirel. Opt. Commun. Pub Date : 2007-09-01 DOI: 10.1142/S0219799507000692

S. Bhardwaj, Subhash C. Arya, V. Priye

{"title":"Wavelength Selective Auxiliary C-Band ASE Pumping for L-Band EDFA","authors":"S. Bhardwaj, Subhash C. Arya, V. Priye","doi":"10.1142/S0219799507000692","DOIUrl":"https://doi.org/10.1142/S0219799507000692","url":null,"abstract":"The variation of Gain and Noise Figure (NF) at 1580 nm with length of Erbium doped fiber (EDF) for two auxiliary pumping schemes employing narrowband Amplified Spontaneous Emission (ASE) and ASE filtered up to a particular wavelength in C-band, by considering a serially cascaded two stage wideband amplifier model are investigated. It is shown that indeed, there exists a wavelength range of ASE for achieving maximum gain. The gain can be increased by 14 dB if wavelength bandwidth of 1480–1554 nm is selected instead of pumping with the broadband ASE (1480–1700 nm). By auxiliary pump using ASE sliced in the 1533 nm window, gain as high as 28 dB and NF as low as 5.5 dB can be achieved for shorter fiber length. To achieve gain of 25–30 dB for the L-band signal only a EDF length of 30 m is required in the case of tuned ASE launching at 1533 nm as compared to 40 m and 65 m by optimized ASE bandwidth and broadband. The values of noise figure do not show significant variation in any of the three configurations. It is apparent that using single wavelength ASE pumping at 1533 nm reduces the fiber length by 10 m (compared to optimized ASE bandwidth pumping) and by 32 m (compared to broadband ASE bandwidth pumping), when L-band EDFA is designed for 25–30 dB signal gain and NF less than 6 dB. These results will be important in designing cascaded wideband EDFA for Optical Fiber Communication (OFC) systems.","PeriodicalId":185917,"journal":{"name":"Int. J. Wirel. Opt. Commun.","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128890656","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

Estimation of Ultra Wide Band Channel Degrees of Freedom 超宽带信道自由度的估计

Int. J. Wirel. Opt. Commun. Pub Date : 2007-05-01 DOI: 10.1142/S021979950700059X

Rachid Saadane, D. Aboutajdine, A. Hayar, R. Knopp

{"title":"Estimation of Ultra Wide Band Channel Degrees of Freedom","authors":"Rachid Saadane, D. Aboutajdine, A. Hayar, R. Knopp","doi":"10.1142/S021979950700059X","DOIUrl":"https://doi.org/10.1142/S021979950700059X","url":null,"abstract":"Multipath propagation effects encountered in mobile wireless channels provide additional degrees of freedom [Ganesan et al., 2000] that can be exploited via appropriate signaling and reception. In this work, based on a set of measurements conducted at Eurecom, we consider a novel approach of analyzing an Ultra Wide Band (UWB) indoor radio propagation channel by performing an eigen-decomposition and observing the scaling of the number of significant eigenvalues with the channel bandwidth by using the Akaike information criterion (AIC) and Minimum Description Length (MDL). These criterion are applied to estimate the number of degrees of freedom (DoF) of an UWB in an indoor environment. We evaluate our approach under both scenarios, line-of-sight (LOS) and non-line-of-sight (NLOS). Based on AIC and the MDL criterion, we find that this number is large; this has important consequences on the receiver design. We show also, that in opposition to the accepted idea in the literature, the number of Degrees of Freedom (DoF) does not increase linearly with the channel bandwidth. Hence, the results of the estimation of UWB channel entropy confirm that the number of DoF increases sub-linearly with the channel bandwidth.","PeriodicalId":185917,"journal":{"name":"Int. J. Wirel. Opt. Commun.","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124375306","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

Planar Elliptical UWB Antenna with Band-notch Characteristics 带陷波特性的平面椭圆超宽带天线

Int. J. Wirel. Opt. Commun. Pub Date : 2007-05-01 DOI: 10.1142/S0219799507000631

D. D. Krishna, M. Gopikrishna, C. Aanandan, P. Mohanan, K. Vasudevan

引用次数: 6

Application of the parabolic equation Method to Several Canonical Indoor Propagation Problems 抛物方程法在若干典型室内传播问题中的应用

Int. J. Wirel. Opt. Commun. Pub Date : 2007-05-01 DOI: 10.1142/S0219799507000618

N. Noori, H. Oraizi

引用次数: 0