快时变衰落环境中频域均衡系统的干扰抑制问题研究

发布时间：2018-04-13 05:13

  本文选题：快时变衰落 + 频域均衡系统　； 参考：《浙江工业大学》2014年硕士论文

【摘要】：移动宽带无线通信系统通常需要应对快速时变衰落环境下有限频谱带宽的信道时频双选择性引起的干扰问题。因此,带宽受限的双选择性信道中抑制干扰的均衡算法研究意义重大。虽然多载波传输,如正交频分复用(OFDM)技术,在补偿双选择性信道有其特殊的优势且研究成果成熟,但是其中存在的高峰均比、相位噪声敏感度高等问题不利于实际应用。单载波频域均衡(SC-FDE)相比于OFDM来说,峰均比低且具有相近的抗多径性能,因此,近10年来在宽带无线通信的研究中受到了广泛关注。但是其比特流时域调制解调的特性使得其在快时变衰落环境中抗干扰的研究和OFDM系统有所不同。鉴于此,文本开展了对快时变衰落环境中SC-FDE系统干扰抑制问题的研究。本文通过对压缩脉冲响应滤波器(SIRF)的算法研究与设计,在有限长循环前缀(CP)条件下,抑制SC-FDE系统中的干扰以达到降低误码率的同时保持系统频谱效率。本文的主要工作包括了MSSNR-SIRF的改进算法,以及通过理论推导获得快时变衰落信道中抑制干扰的SIRF最佳性能参数设计方案。同时,利用等效噪声近似估计对最佳SIRF下最小均方误差准则(MMSE)频域均衡器进行了改进,在一定程度上抑制了噪声干扰。本文的主要结构分为四个部分。首先,本文分析了快时变衰落中信道的特性,着重于其双选择特性,结合各种帧结构的特点详细阐述了SC-FDE的基本原理；通过SC-FDE系统数学模型分析在快时变衰落环境中的干扰问题,给出了干扰的数学表达式。其次,介绍了信道压缩算法,给出了克服滤波器长度受限及复杂度高的最大化缩短信噪比(MSSNR)算法的改进方案。接着,通过在SC-FDE系统中应用SIRF时的余留干扰表达式的推导,得出了SIRF改进算法在系统中应用的设计方案,并给出了频域均衡MMSE算法等效噪声估计。最后,通过Matlab仿真结果对上述理论结果进行验证,得出快时变衰落环境中CP不足SC-FDE系统结合最佳参数设计的SIRF的线性均衡的抗干扰性能。
[Abstract]:Mobile broadband wireless communication systems usually need to deal with the interference caused by time-frequency double selectivity in the channel with limited spectrum bandwidth in fast time-varying fading environment.Therefore, it is of great significance to study the interference suppression equalization algorithm in band-limited dual selective channels.Although multicarrier transmission, such as orthogonal frequency division multiplexing (OFDM) technology, has its special advantages in compensating dual selective channels and its research results are mature, the problems such as peak to average ratio and high phase noise sensitivity are not conducive to practical application.Compared with OFDM, SC-FDE (single Carrier Frequency Domain Equalization) has low peak-to-average ratio (PAPR) and similar anti-multipath performance. Therefore, SC-FDE has attracted much attention in the research of broadband wireless communication in recent 10 years.However, the characteristics of bit stream time domain modulation and demodulation make the research of anti-jamming in fast time-varying fading environment different from that of OFDM system.In view of this, the paper studies the interference suppression problem of SC-FDE system in fast time varying fading environment.In this paper, the algorithm of compressed impulse response filter (SIRF) is studied and designed. Under the condition of finite length cyclic prefix (CPP), the interference in SC-FDE system is suppressed to reduce the bit error rate (BER) and maintain the spectral efficiency of the system.The main work of this paper includes the improved algorithm of MSSNR-SIRF and the optimal performance parameter design of SIRF in fast time-varying fading channels.At the same time, the minimum mean square error criterion (MMSE) frequency domain equalizer under the optimal SIRF is improved by using the equivalent noise approximate estimation, which can restrain the noise interference to some extent.The main structure of this paper is divided into four parts.Firstly, this paper analyzes the characteristics of the channel in fast time-varying fading, focusing on its dual selection characteristics, and expatiates on the basic principle of SC-FDE in combination with the characteristics of various frame structures.Based on the mathematical model of SC-FDE system, the interference problem in fast time-varying fading environment is analyzed, and the mathematical expression of interference is given.Secondly, the channel compression algorithm is introduced, and an improved scheme is proposed to overcome the filter length limitation and the complexity of the maximum shortened SNR (MSSNR) algorithm.Then, through the derivation of residual interference expression when SIRF is applied in SC-FDE system, the design scheme of SIRF improved algorithm applied in the system is obtained, and the equivalent noise estimation of frequency domain equalization MMSE algorithm is given.Finally, the theoretical results are verified by Matlab simulation results, and the linear equalization performance of SIRF in fast time-varying fading environment with CP deficient SC-FDE system combined with optimal parameters is obtained.
【学位授予单位】：浙江工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN911.4
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本文编号：1743066