基于非理想CSI的V-BLAST系统功率分配算法研究

发布时间：2018-01-09 08:36

  本文关键词：基于非理想CSI的V-BLAST系统功率分配算法研究　出处：《南京航空航天大学》2014年硕士论文　论文类型：学位论文

  更多相关文章： MIMO V-BLAST OFDM 功率分配 信道相关 估计误差 反馈延迟 误比特率

【摘要】：V-BLAST结构是一种基于MIMO方式的传输技术,它能较好的利用多天线系统的信道容量及频谱效率。在V-BLAST结构中应用OFDM技术可有效抵抗多径衰落并缓解符号间干扰。自适应功率分配算法能根据信道环境动态变化实现各发射天线功率的自适应调整。本文在信道相关、信道估计有误差以及信道反馈有延迟条件下,研究了V-BLAST及V-BLAST OFDM系统的自适应功率分配算法,以期所提发射功率分配方案能更好的提升系统性能,并为实用提供依据。全文主要工作如下:1.针对传统V-BLAS系统,不考虑传播误差,采用ZF及MMSE干扰抵消检测方式时,推导了系统子流误比特率(BER)的近似表达式。同时在完全信道状态信息(CSI)条件下研究了基于拉格朗日极值法与基于等信干噪比(SINR)的发射功率分配方案。通过仿真验证理论推导及功率分配方案的有效性。2.针对信道相关及存在估计误差的V-BLAST系统,以最小化平均BER为目标,分别得到基于ZF及MMSE检测时V-BLAST系统的发射功率分配方案。考虑到系统BER性能随着信道相关性的增加而下降,根据信道信息引入去相关方法以达到改善系统BER的目的。对所提发射功率分配方案进行仿真同时给出详细分析。与传统等功率分配方案相比,采用所提发射功率分配方案结合去相关方法可显著改善系统性能。3.针对信道估计有误差及反馈有时延的V-BLAST系统,以最小化平均BER为目标,提出一种基于MMSE检测的自适应功率分配方案。由信号估计信干噪比(SINR)的概率密度函数(PDF)推导出系统子流瞬时信干噪比的条件PDF以及系统瞬时BER表达式。以最小化平均BER为目标建立代价函数得到自适应功率分配方案。仿真显示,所提算法能获得比等功率分配方案更好的性能,在改善系统BER的同时更具实效性。4.针对信道相关及估计有误差的V-BLAST OFDM系统,以最小化BER为目标提出一种自适应功率分配方案。考虑到信道相关的影响,应用去相关方法。仿真显示,将发射功率分配方案及去相关方法应用到V-BLAST OFDM系统中,在克服频率选择性信道中的符号间干扰的同时提升了系统性能。
[Abstract]:V-BLAST structure is a transmission technology based on MIMO. It can make good use of the channel capacity and spectrum efficiency of multi-antenna system. The application of OFDM technology in V-BLAST structure can effectively resist multipath fading and mitigate inter-symbol interference. Adaptive power allocation algorithm can. Adaptive adjustment of transmit antenna power is realized according to the dynamic change of channel environment. The adaptive power allocation algorithms for V-BLAST and V-BLAST OFDM systems are studied under the condition of channel estimation error and channel feedback delay. It is expected that the proposed scheme can improve the system performance better, and provide a basis for practical use. The main work of this paper is as follows: 1. For the traditional V-BLAS system, the propagation error is not considered. When using ZF and MMSE interference cancellation detection method. The approximate expression of sub-stream error bit rate (ber) of the system is derived. At the same time, under the condition of complete channel state information (CSI), the Lagrangian extremum method and the equal-signal-to-noise ratio (SINR) are studied. The efficiency of the scheme is verified by simulation. 2. The V-BLAST system is designed for channel correlation and estimation error. The goal is to minimize the average BER. The transmission power allocation scheme of V-BLAST system based on ZF and MMSE detection is obtained, considering that the BER performance of the system decreases with the increase of channel correlation. According to the channel information, the de-correlation method is introduced to improve the BER of the system. The proposed transmission power allocation scheme is simulated and analyzed in detail. Compared with the traditional equal-power allocation scheme. The proposed transmit power allocation scheme combined with de-correlation method can significantly improve the system performance. 3. For V-BLAST systems with channel estimation errors and feedback delays, the objective is to minimize the average BER. An adaptive power allocation scheme based on MMSE detection is proposed. The probability density function (PDF) of signal-to-noise ratio (SINR) is estimated from the signal. The conditional PDF of the system subflow instantaneous signal-to-noise ratio and the instantaneous BER expression of the system are derived. The adaptive power allocation scheme is obtained by establishing the cost function to minimize the average BER. The proposed algorithm can achieve better performance than the equal-power allocation scheme and improve the efficiency of the system BER at the same time. 4. For the channel correlation and estimation error V-BLAST OFDM system. An adaptive power allocation scheme aiming at minimizing BER is proposed. Considering the influence of channel correlation, the de-correlation method is applied. The transmit power allocation scheme and de-correlation method are applied to V-BLAST OFDM system, which can overcome the intersymbol interference in frequency selective channel and improve the system performance.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN919.3
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本文编号：1400740