共查询到18条相似文献,搜索用时 78 毫秒
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下行多点协作传输系统中基于大尺度信道的协作用户选择 总被引:1,自引:0,他引:1
研究下行多点协作传输系统中的协作用户选择问题.首先分析下行多基站协作系统中空域满复用服务多用户的必要性,而后研究满复用传输时的协作用户选择方法,被选为一组的用户在相同的时频资源上由多个基站以协作空分多址的方式服务.分析表明,每个被服务用户的平均接收信干噪比与相邻协作小区内被服务用户的大尺度信干比成递增关系.在此基础上,提出一种基于大尺度信干比的协作用户选择方法.仿真结果表明,与现有基于大尺度信道信息的用户选择方法相比,所提出的方法以较小的小区平均数据率损失为代价,大幅度提升了小区边缘用户数据率. 相似文献
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本文研究了基于不完全信道信息和天线选择的多用户MIMO系统下行链路性能。通过系统建模和性能分析,利用数学变换和条件概率密度函数,推导了有着不完全反馈信息时的系统误比特率(BER)准确表达式。该式可有效评估反馈时延对系统性能的影响,且包含了基于完全反馈信息的系统BER公式作为其特殊情况。为简化准确表达式中的积分计算,还利用互补误差函数的近似值推导了系统BER的近似表达式,可得到较为简单的闭式表达式。计算机仿真结果表明:所给的准确及近似理论分析可与仿真结果取得较好的一致;且当归一化时延低于0.01时,系统性能较之完全信道信息情况仅有轻微的下降。 相似文献
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多用户检测技术在实际应用中,难以解决的问题是在减少计算复杂度的同时又提高系统性能。本文针对空时CDMA系统设计了一种多用户检测算法,即附带噪声梯度的最速下降算法。此算法利用变步长迭代的思想实现多用户检测,避免了最小均方误差(MMSE)多用户检测庞大而复杂的求逆运算和固定步长收敛速度较慢的问题。计算机仿真结果表明,在空时CDMA系统中使用本文算法,收敛速度大大增加,同时在保持系统性能的前提下能够容纳较多的用户。 相似文献
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一种多用户MIMO-OFDM系统中的天线与子载波分配算法 总被引:1,自引:0,他引:1
天线与子载波分配是多用户MIMO-OFDM系统无线资源管理中的重要内容.在分析了多用户MIMO-OFDM系统下行链路中最优天线与子载波分配算法的基础上,提出了一种次优的低复杂度天线与子载波分配算法.该算法通过先选择天线再选择用户从而避免了最优算法中的遍历搜索.仿真结果表明,在运算量大大降低的情况下,所提算法获得的系统最大容量和最优算法所获得的最大容量相比相差不大,而且空间和频率联合优化的结果使其性能远远优于仅在MIMO环境下进行子载波分配的算法. 相似文献
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毫米波混合波束成形结构受到日益广泛的认可,但缺乏以安全性为着眼点的混合波束成形算法研究,特别是当窃听者具有多用户译码能力时,系统安全性能无法得到保障。针对上述问题,该文基于人工噪声辅助的思想提出一种毫米波下行多用户系统安全混合波束成形算法。首先,将混合波束成形矩阵的模拟部分和数字部分解耦合独立求解,在充分考虑信道特性的基础上,通过最大化用户接收信号能量和迫零思想分别设计有用信号的模拟和数字波束成形矩阵;然后,通过SVD分解设计人工噪声的基带数字预编码矩阵,将人工噪声置于合法用户零空间。仿真结果表明,人工噪声辅助的安全混合波束成形算法有效解决了存在具有多用户译码能力窃听者时系统的安全问题。
相似文献14.
By pre-equalizing inter-stream interference at the transmitter, Tomlinson–Harashima precoding (THP) algorithm provides a solution
for the downlink of multiple antenna multi-user systems, in which the decentralized structure of the receivers makes the receiver-processing
impossible. However, for the zero-forcing (ZF) THP algorithm available in the literature there are significant performance
differences between specific mobile stations. In this paper, a novel version of the THP algorithm is proposed. It greatly
improves the worst mobile's performance and ensures balanced performance of all the mobiles. For the new THP algorithm, better
performance can be obtained by suitably ordering the rows of the channel matrix. We show that the “best-first” ordering method
achieves optimal order for BER performance in systems with two mobile stations and achieves near optimal order in systems
with more than two mobile stations. Simulation is used to show the advantages of the new THP algorithm and the “best-first”
ordering method.
Jia Liu received the B.E. and M.Sc. degrees in electrical engineering from Beijing University of Posts and Telecommunications, Beijing,
China, in 1998 and 2001, respectively. Between 2001 and 2002, she worked as a system engineer in Siemens Ltd. (China), ICM
N R&D, TD-SCDMA. She is currently pursuing a Ph.D. degree at the Department of Electrical and Computer Engineering, University
of Alberta, and at TRLabs in Edmonton, Alberta, Canada. Her current research interests include broadband wireless communications,
multiple input multiple output (MIMO) antenna systems, precoding for multi-user MIMO, signal detection, and multi-user interference
cancellation.
Witold A. Krzymień received his M.Sc. (Eng.) and Ph.D. degrees (both in Electrical Engineering) in 1970 and 1978, respectively, from the Poznań
University of Technology in Poznań, Poland. He received a Polish national award of excellence for his PhD thesis.
Since April 1986 he has been with the Department of Electrical & Computer Engineering at the University of Alberta, Edmonton,
Alberta, Canada, where he currently holds the endowed Rohit Sharma Professorship in Communications & Signal Processing. In
1986, he was one of the key research program architects of the newly launched TRLabs, Canada's largest industry-university-government
pre-competitive research consortium in the Information & Communication Technology area, headquartered in Edmonton. His research
activity has been closely tied to the consortium ever since.
Over the years Dr. Krzymień has also done collaborative research work with Nortel Networks, Ericsson Wireless Communications,
German Aerospace Centre (DLR -Oberpfaffenhofen), Telus Mobility and the University of Padova (Italy). He has held visiting
research appointments at Twente University of Technology (Enschede, The Netherlands; 1980-1982), Bell-Northern Research (Montréal,
Canada; 1993-1994), Ericsson Wireless Communications (San Diego, USA; 2000), Nortel Networks Harlow Laboratories (Harlow,
UK; 2001), and the Department of Information Engineering at the University of Padova (2005).
His research is currently focused on broadband high throughput packet data access for mobile and nomadic users, employing
multi-carrier signalling, multiple antenna techniques and link adaptation, as well as on the related MAC and network layer
issues of hybrid ARQ, packet scheduling and relaying.
Dr. Krzymień is a Fellow of the Engineering Institute of Canada, and a licensed Professional Engineer in the Provinces of
Alberta and Ontario, Canada. From 1999 to 2005 he was the Chairman of Commission C (Radio Communication Systems and Signal
Processing) of the Canadian National Committee of URSI (Union Radio Scientifique Internationale). He received the 1991/1992 A.H. Reeves Premium Award from the Institution of Electrical Engineers (U.K.) for a paper published
in the IEE Proceedings, Part I. 相似文献
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一般的空时编码解码时接收端需要信道状态信息(CSI),因而必须获得精确的信道估计;而差分空时编码(DSTC)接收端解码时不需要CSI,因而不需要信道估计。在信道衰落快或信息传输速率高的情况下,实时而精确的信道估计非常困难或代价很高,此时接收端不能获得CSI,因而需要差分空时编码。文章对多发射天线的差分空时编码的编译码原理、特点和性能进行了分析和比较,并对其中的部分差分空时编码给出了具体的实例和仿真结果。 相似文献
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天线选择是MIMO系统中一项重要的技术,它能从MIMO系统的多个发射天线和多个接收天线中选择出性能最好的一个或几个天线,从而以很小的性能损失换取成本的大幅降低,极大地提高了MIMO系统的性能价格比。最优算法具有较高的复杂度而限制了它的应用,文中从次优的递增递减算法入手,提出了一种具有更低复杂度的递增递减接收天线选择算法。仿真结果表明,该算法以很小的系统容量损失为代价换取了复杂度的降低。 相似文献
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研究了在频分双工智能天线系统中基站与移动台之间上下行信道的协方差矩阵,根据不随频率变化的上下行信道特性,得到下行的协方差矩阵,以使期望用户接收的信干噪比最大为准则确定下行波束形成的权矢量,不需要估计用户的DOA和平均信号强度的信息。计算机仿真进一步显示了算法的性能。 相似文献