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An introduction to multihop multi-antenna communications

FREQUENZ 2006年第5-6期60卷 103-106页

作者： Thompson, John S. Grant, Peter M. Fan, Yijia Univ Edinburgh Sch Engn & Elect Edinburgh EH9 3JL Midlothian Scotland

Recently there has been significant interest in the use of multihop wireless links for use in mobile communications. In such a system, data is forwarded by one or more relays from the source to the destination, rather than simply via a direct wireless link. This paper focuses on how such techniques can be combined with antenna array processing techniques, where multiple antennas are used at each terminal. We discuss a novel multihop approach called hybrid relaying, which combines amplify and forward relaying with spatial processing. Its performance is compared with other relaying techniques. We also investigate the best approach to exploiting the availability of multiple relays. Our results suggest it is better to use the single best relay to forward to the destination than to try to forward signals via multiple relays.

关键词： wireless relaying multihop antenna array processing multiple input multiple output

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Measurement of direction-of-arrival of coherent signals using five-port reflectometers and quasi-Yagi antennas

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IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS 2005年第9期15卷 558-560页

作者： Vu, VY Braga, AJ Begaud, X Huyart, B Ecole Natl Super Telecommun Bretagne F-75013 Paris France

The measurement results of detection-of-arrival (DoA) of coherent signals using five-port reflectometers and quasi Yagi antennas are presented. The receiver operating at 2.4 GHz consists of eight five-port reflectometers and a uniform linear array (ULA) of eight 2.4 GHz quasi-Yagi antennas. The DoA is estimated by measuring the phase difference of signals pitched by the antenna array and by using the MUSIC algorithm associated with Spatial Smoothing Pre-processing (SSP). The phase difference is determined using the five-port technique. The measurement results show that the DoA of coherent signals are well estimated with a maximum error of 2 degrees. In addition, we also show that it is capable of estimating the time delay and direction of arrival simultaneously using the five-port technique.

关键词： antenna array processing direction of arrival five-port MUSIC spatial smoothing time delay

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A novel space-time transmit diversity technique for LAS-CDMA

A novel space-time transmit diversity technique for LAS-CDMA

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Global Mobile Congress 2005

作者： Zou Yongzhong Li Daoben Beijing Univ Posts & Telecommun Dept Informat Engn Beijing 100876 Peoples R China

This paper presents a new two-branch space-time transmit diversity scheme for LAS-CDMA system, which differs from the current 3G transmit diversity methods, such as space-time transmit diversity (STTD) of W-CDMA and orthogonal transmit diversity (OTD) and space-time spreading (STS) of cdma-2000. Using two transmit antennas and two receive antennas, the new scheme provides diversity order of four. This new technique does not require any bandwidth expansion and any feed back from the receiver to the transmitter and its computation complexity is similar to MRC. This new space-time transmit diversity scheme has lower Peak-to-Average power Ratio (PAR), less multiple access interference and better performance, especially in the high mobility environment.

关键词： antenna array processing maximal-ratio combining space-time spreading space-time coding transmit diversity LAS-CDMA

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Resolving the ambiguities due to spatial undersampling in wideband uniform linear arrays

Resolving the ambiguities due to spatial undersampling in wi...

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Conference on Multispectral and Hyperspectral Remote Sensing Instruments and Applications II

作者： Shapoury, A Georghiades, CN Texas A&M Univ Dept Elect Engn College Stn TX 77843 USA

ISBN: (纸本)0819456160

In array signal processing in general, we often wish to fuse the collected data at several sensor elements and implement a given estimation or detection task. This study is a selective treatment of the wideband array processing under some specific assumptions. Shannon Spatial Sampling Limit defines an upper bound for the Frequency of transmission given certain element spacings in arrays. Beyond this bound, the exceeded ambiguity due to spatial aliasing. avoids correct estimation of the signal parameters -e.g. the Direction Of Arrival (DOA), which is of our interest in this study. In another vein, decreasing the element spacing to meet a wider spectral support is difficult to implement due to the electromagnetic mutual coupling of the sensor elements in the array and the reduction of the resolution*. This work is an attempt to develop a methodology for resolving this ambiguity or aliasing in the wideband scenario using statistical signal processing. Our approach is heuristic. We consider known implementations, adopt them to meet our scenario and then analyze the performance of our proposed method. Although the models and the formulations presented in this survey can be further generalized. we limit our discussion mainly to the Uniform Linear arrays (ULA). Many of the topics discussed in this study have a potential for being useful in practical applications, since they would allow a realistic modeling and offer more flexibility than the conventional array processing framework, hence we believe that there is already sufficient interest in this study.

关键词： antenna array processing Ultra Wideband (UWB) aliasing uniform linear array DOA estimation beamforming

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Measurement of direction-of-arrival of coherent signals using five-port reflectometers and quasi-Yagi antennas

Measurement of direction-of-arrival of coherent signals usin...

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7th European Conference on Wireless Technology (ECWT2004)

作者： Vu, VY Braga, AJ Begaud, X Huyart, B Ecole Natl Super Telecommun Bretagne F-75013 Paris France

关键词： antenna array processing direction of arrival five-port MUSIC spatial smoothing time delay

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Extending orthogonal block codes with partial feedback

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2004年第6期3卷 1959-1962页

作者： Akhtar, J Gesbert, D Univ Oslo Dept Informat N-0316 Oslo Norway Eurecom Inst Mobile Commun Dept F-06904 Sophia Antipolis France

During the last few years a number of space-time block codes have been proposed for use in multiple transmit antennas systems. In this paper we propose a method to extend any space-time code constructed for m transmit antennas to m p transmit antennas through group-coherent codes (GCCs). GCCs make use of very limited feedback from the receiver (as low as 1 bit). In particular the scheme can be used to extend any orthogonal code (e.g., Alamouti code) to more than two antennas while preserving low decoding complexity, full diversity benefits, and full data rate.

关键词： antenna array processing diversity space-time block codes transmit diversity

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A Novel Space-time Spreading Transmit Diversity Scheme for Wireless CDMA System

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The Journal of China Universities of Posts and Telecommunications 2004年第2期11卷 72-79页

作者： ZOUYong-zhong LIDao-ben Information EngineeringSchool Beijing University of Posts and TelecommunicationsBeijing100876P.R.China

This paper presents a new two-branch space-time spreading transmit diversity scheme for wireless CDMA systems, which differs from Space-Time Spreading (STS) of CDMA-2000. Using two transmit and M receiving antennas, the new scheme provides diversity order of 2M. This new technique does not require any bandwidth expansion and any feed back from the receiver to the transmitter and its computation complexity is similar to the Maximal-Ratio Combining (MRC).

关键词： antenna array processing maximal-ratio combining space-time spreading transmit diversity CDMA

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A fast recursive algorithm for optimum sequential signal detection in a BLAST system

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IEEE TRANSACTIONS ON SIGNAL processing 2003年第7期51卷 1722-1730页

作者： Benesty, J Huang, YT Chen, JD Lucent Technol Bell Labs Murray Hill NJ 07974 USA

Bell Laboratories layered space-time (BLAST) wireless systems are multiple-antenna communication schemes that can achieve very high spectral efficiencies in scattering environments with no increase in bandwidth or transmitted power. The most popular and, by far, the most Practical architecture is the so-called vertical BLAST (V-BLAST). The signal detection algorithm of a V-BLAST system is computationally very intensive. If the number of transmitters is M and is equal to the number of receivers, this complexity is proportional to M-4 at each sample time. In this paper, we propose a very simple and efficient algorithm that reduces the complexity by a factor of M.

关键词： antenna array processing Bell Laboratories layered space-time (BLAST) architecture multiple-input-multiple-output (MIMO) systems

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Dynamic signal enumeration algorithm for smart antennas

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IEEE TRANSACTIONS ON SIGNAL processing 2002年第6期50卷 1307-1314页

作者： Green, PJ Taylor, DP Univ Canterbury Dept Elect & Elect Engn Christchurch 1 New Zealand

This paper develops a method to enumerate the incident signals impinging on a uniform linear array (ULA) independent of the extent of their correlation in a Rayleigh flat fading channel environment. The method also minimizes the number of antennas to the number of signals and adapts continuously to maintain performance in a mobile environment where users (signals) come and go. It ensures that the amount of computation is kept to a minimum and, in a practical system, can reallocate computational resources to other applications. The technique is a modification of the matrix decomposition method of Cozzens and Sousa. A new set of stability, stopping, and adaptive control criteria is presented. An algorithm is formulated, and simulation results are presented, showing performance and behavior at various signal-to-noise ratios (SNRs). Limitations of the algorithm in enumerating closely spaced signals are also presented.

关键词： antenna array processing signal enumeration smart antennas

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Joint iterative multiuser and narrowband interference suppression in coded asynchronous DS-CDMA channels

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WIRELESS PERSONAL COMMUNICATIONS 2001年第1期16卷 69-92页

作者： Thomas, J Geraniotis, E Univ Maryland Dept Elect & Comp Engn College Pk MD 20742 USA Univ Maryland Syst Res Inst College Pk MD 20742 USA

Multiuser interference suppression in coded direct sequence: code division multiple access (DS-CDMA) uplink channels is significantly impacted by the application of the turbo processing concept. This paradigm essentially involves the iterative exchange of soft information between a multiuser demodulator and a bank of single-user decoders, to their mutual benefit. The present work proposes a joint iterative minimum mean square error (MMSE) multiuser and narrowband interference suppressor for coded asynchronous DS-CDMA channels. Since the parameters of the narrowband interference are unknown a priori, the first iteration in this scheme is effectively just MMSE multiuser interference suppression. The outputs of all users' soft decoders (available at the end of each iteration) are fed back to subtract their (estimated) cumulative contribution from the received signal vector. The residue comprises the narrowband interference embedded in wideband noise, so that the former can be piecewise interpolated over chip intervals of appropriate duration, and then subtracted from the received signal, to provide a narrow-band-interference e-free input signal for the: next iteration. The soft-decoded feedback estimates of the interferers' signals are used in each iteration also to perform soft MMSE multiuser interference suppression, in conjunction with subtractive interference cancellation. This scheme performs well at both low and high received signal powers, and displays the successive cancellation property across iterations, exhibiting good near-far resistance. introducing multisensor arrays at the receiver relaxes the limitations imposed by the inherent suboptimality of MMSE multiuser demodulation, insofar as it enhances interuser separation, now in the spatial sense. Simulations indicate that the performance of the proposed technique surpasses that of all existing suboptimal algorithms in this context.

关键词： multiuser interference suppression narrowband interference suppression iterative (turbo) processing antenna array processing

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