共查询到17条相似文献,搜索用时 93 毫秒
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本文提出了一种采用分布式差分空时分组编码和检测的协同分集方案,在不需要信道状态信息(CSI)的情况下可以实现满分集和全速率发射,并推导了相关瑞利信道下该方案误码率(BER)性能上限的解析表达式。传统的差分空时分组编码对整个码块进行差分,而协同分集下的任何一个协同用户进行差分编码时都不知道整个码块的信息。本文所提出的差分BPSK调制方案,通过将两协同用户的信息分别被调制到相互正交的实轴和虚轴上,从而将码块的联合差分转化为各用户独立差分。分析了在协同用户间不同的信道状态信息(CSI)和协同用户到接收用户不同的CSI情况下本文所提出发射方案的性能。仿真结果表明本文所提出的方案获得了明显的分集增益,同时也较好的吻合了理论分析的结果。 相似文献
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发射分集系统在空间相关莱斯快衰落信道下的性能 总被引:2,自引:0,他引:2
采用空时编码的发射分集系统的性能分析是当前移动通信研究领域的热点问题。相对准静态独立的瑞利衰落信道模型而言,空间相关莱斯快衰落信道更适用于实际情况。但由于在空间相关莱斯快衰落情况下,发射分集系统的性能分析比较复杂,因此关于这方面的论文较少。本文利用多变量统计学理论,得到发射分集系统在空间相关莱斯快衰落信道下平均成对差错概率上界的闭合表达式,并详细说明了信道特性对系统性能的影响。最后给出了仿真结果。 相似文献
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基于空时分组编码的差分检测方法 总被引:1,自引:1,他引:0
利用正交设计原理提出了通用的差分空时分组码(GDSTBC,general differential space-time block code)。与已有的差分调制方法相比,GDSTBC对信号星图无任何限制,因而可利用幅度和相位同时携带信息提高频谱效率。基于最大似然准则,给出了平坦。Rayleigh衰落信道下的非相干译码器。我们将证明:在高信噪比下,GDSTBC能够以线性复杂度和满天线分集恢复数据符号;在PSK调制方式下,没有信道估计时性能下降3dB;Ganesan基于PSK星图的差分空时分组码、Xia基于APSK星图的差分空时调制技术都可看成GDSTBC的特例。 相似文献
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基于对角信号的差分酉空时调制技术不需要信道估计并能实现满天线分集,但接收机的计算复杂度与发射天线数和数据率成指数关系。该文针对发射天线数为偶数的系统,提出了一种降低接收机计算复杂度的差分空时调制方案。该方案将发射天线分成相等数目的两组并在每一组天线上分别进行对角酉空时调制,接着构造差分编码矩阵使得两个对角信号的最大似然检测可以分开进行,从而大大降低了接收机的计算复杂度。理论分析和仿真表明,该方案仍实现了满天线分集,并且对于某些应用环境能提供比对角信号更好的误比特率性能。 相似文献
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发射分集(TD:transmit diversity)是第3代移动通信(3G)cdma2000和WCDMA系统采用的一项关键技术。它利用发射天线空间分隔以获得相互独立的衰落信号的发射和接收,改善系统性能。文中主要描述了几种发射分集技术的概念,特点及性能。 相似文献
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ZOU Yong-zhong LI Dao-ben Information Engineering School Beijing University of Posts Telecommunications Beijing P.R. China. 《中国邮电高校学报(英文版)》2004,11(2)
1 Introduction Thefundamentalchallenge,whichmakesreliablewirelesstransmissiondifficult,isthetime varyingmulti pathfading .Theoretically ,themosteffectivetechniqueformitigatingmulti pathfadinginawire lesschannelistransmitterpowercontrol.ButinCDMAsystems,powercontrolislimitedbythetransmitterdynamicrangeandthenear fareffect.Diversityisanefficientandpracticaltechniquetocombattime varyingmulti pathfading .Andanten nadiversityiswidelyappliedtoreducetheeffectofmulti pathfading .Theclassicalappro… 相似文献
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Murat Torlak 《Wireless Personal Communications》2004,28(4):277-286
Many theories of exploiting spatial diversity in wireless communications and more recently space-time coding are results of
understanding the spatial channel models for antenna array communication systems. For example, the models for rich scattering
environments assume the channel coefficients to be almost independent when the spacing between the antennas is sufficient.
This could limit the possibility of extracting direction of the signal propagation with respect to antenna locations (G. Xu
et al., IEEE Transactions on Signal Processing, Vol. 42, No. 2, pp. 349–355, 1994). On the other hand, when the scattering is limited to few dominant reflectors, the directions
of the signals traveling through the environment can prevail in the channel coefficients. Extracting the propagation direction
(beam direction) information from the channel coefficients has been investigated extensively in array signal processing literature.
These investigations have led to many algorithms of direction of arrival (DOA) estimation and beamforming. Here, we propose
a transmit diversity technique that exploits beam directions in environments with few beam directions. While we present this
technique for two-beam Rayleigh fading channels (J.E. Mazo, IEEE Transaction on Communication, Vol. 39, No. 7, pp. 1027–1030, 1991), it can be easily extended to multibeam general fading channels. The proposed method
does not require feedback from the receiver. 相似文献
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在分析接收分集技术最大比率接收合并(MRRC)方案的基础上,介绍了一种两分支发送分集方案。该方案采用2个发射天线、1个接收天线,可提供与1个发送天线、2个接收天线情况下的MRRC方案相同的分集增益。由于发送符号采用了正交性设计,该发送分集方案在接收端可以将不同的发送符号分离开来,分别进行最大似然检测。仿真结果表明,运用分集技术可大大改善无线通信系统的性能,且该方案和一发两收的MRRC方案性能相似、计算复杂性相同。该发送分集方案能更好地应用于移动通信系统。 相似文献
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Focusing on the problem that differential spatial modulation (DSM) couldn’t obtain transmit diversity and has high decoding complexity,a new differential spatial modulation scheme based on the orthogonal space-time block code was proposed and the proposed scheme is called OSTBC-DSM.There were two matrices in this scheme:the spatial modulation matrix and the symbol matrix.The former was aimed to activate different transmit antennas by setting the position of nonzero elements,and the latter structured symbolic matrix by using orthogonal space-time block codes (OSTBC) as the basic code block.The proposed scheme could obtain full transmit diversity and higher spectral efficiency compared with the conventional DSM schemes.Moreover,the OSTBC-DSM supported linear maximum likelihood (ML) decoding.The simulation results show that under different spectral efficiencies,the proposed OSTBC-DSM scheme has better bit error rate (BER) performance than other schemes. 相似文献