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Han‐Shin Jo 《ETRI Journal》2011,33(6):831-840
This paper focuses on codebook‐based precoding for space‐division multiple access/orthogonal frequency‐division multiple access (SDMA‐OFDMA) systems aiming to guarantee high throughput for their users as well as to mitigate interference to fixed satellite service (FSS). A systematic design of SDMA codebook for subband‐based OFDMA is proposed, which forms multiple orthogonal beams with common spatial null in the direction of a victim FSS earth station (ES). The design enables both transmitter and receiver to independently construct identical codebook by sharing only on the direction angle of an FSS ES, which takes fewer overhead bits than Gram‐Schmidt process, a general method satisfying our design criterion. A system‐level throughput evaluation shows that the proposed precoding provides superior performance over existing spectrum sharing method, that is, subband deactivation. The spectrum sharing analysis shows that the proposed precoding, even with an estimation error of the direction angles of an FSS ES, causes lower interference than existing precoding, knockdown precoding. 相似文献
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Shiann‐Shiun Jeng Hsin‐Piao Lin Chen‐Wan Tsung 《International Journal of Communication Systems》2003,16(3):211-223
This paper presents some preliminary results from experimental studies on space‐division‐multiple‐access (SDMA) for wireless communications. A smart antenna system utilizing direction‐of‐arrival (DOA)‐based beamforming techniques can enhance signal quality by reducing co‐channel interference from mobiles located at angles spatially distinct from the base station. Adopting both smart uplink and downlink beamforming, a communication system with an antenna array can increase the cell coverage of a base station and significantly boost capacity compared with conventional antenna systems. However, successful implementation of DOA‐based beamforming techniques depends on the DOA characteristics. This paper presented the feasibility of direction finding and DOA variation with respect to frequency. Furthermore, the angle spread was studied for selected environments. The results demonstrate the feasibility of applying proposed smart antenna system utilizing DOA‐based beamforming algorithm for increasing channel capacity and improving system performance in frequency‐division‐duplex (FDD) wireless communication systems. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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Teletraffic Analysis of SDMA-Systems with Inhomogeneous MS Location Distribution and Mobility 总被引:1,自引:0,他引:1
One of the most widely used buzzwords in mobile communications of the recent years is Space Division Multiple Access (SDMA). The introduction of an additional space domain multiple access component is likely to boost system capacity, due to the spatial reuse of physical channels within one cell. While early approaches of SDMA system modelling show capacity to be gained in the order of 300 to 400%, there remains some more in depth system analysis to be done, as inhomogeneities in the user distribution are expected to likely cause dramatic drops in the additional capacity gained by SDMA. The spatial distribution of terminals directly influences the number of channels to be gained by spatial multiplexing. Therefore, it is not until detailed models for user distribution, user mobility and the traffic load generated by users are combined with a model of the SDMA radio subsystem, that realistic approximations for these capacity gains are possible. In this paper, we discuss the issues in modelling and simulation of SDMA systems. We present an approach for integrated SDMA system modelling, discuss analytic teletraffic dimensioning methods for macro- and microcellular environments and their relevance to SDMA systems, and present some early simulation results. 相似文献
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在多用户MIMO通信网络中,该文提出一种新的放大转发双向中继策略,在第1时隙的多址传输中采用OFDMA,在第2时隙的广播传输中采用OFDM/SDMA,通过利用频率分集和空间分集提高了系统性能。针对双向中继传输的特点,采用两种方法在每个子载波上设计了中继波束形成矩阵,即信漏噪比(SLNR)准则和块对角化迫零(BDZF)准则。利用割集理论推导了该双向中继网络的容量域上界。仿真结论表明,所提出的双向中继策略在系统和速率性能上优于其他3种中继策略,并能逼近所推导的容量域上界。 相似文献
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现代无线移动通信系统广泛考虑采用空分多址(SDMA)多址接入技术来提高系统容量。比如在频分复用(FDMA)时分复用(TDMA),码分复用(CDMA)。分析研究SDMA系统中的FD信道分配机制,给出了理论推导,并在此基础上进行了仿真。仿真结果表明:采用该机制以后,用户可以在同一时间共享同一信道。 相似文献
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多址接入技术是无线通信系统设计的一个重要因素,未来无线通信系统将广泛采用空分多址(SDMA)接入技术来提高系统容量。比如在频分复用(FDMA),时分复用(TDMA),码分复用(CDMA)。介绍了Erlang-B分布这一典型的业务分配模型,并考虑了SDMA系统中DL信道分配机制,给出了理论推导,并采用一般的排队论模型对数字蜂窝移动通信系统中SDMA技术进行仿真。仿真结果表明:采用DL信道分配机制以后,用户可以在同一时间共享同一信道。 相似文献