单载波传输系统均衡技术研究

发布时间：2018-04-03 05:09

  本文选题：均衡器　切入点：单载波系统　出处：《东南大学》2015年硕士论文

【摘要】：无线通信信道的多径效应会引起码间干扰现象,进而影响通信质量,解决该问题的一个重要方法是均衡器。本文研究了单载波通信系统中的均衡器设计,包括时域最小均方误差准则均衡算法,频域块迭代判决反馈均衡算法和时频混合判决反馈均衡算法等,同时还针对室内可见光通信和对流层散射通信这两个应用场景,设计了相应的硬件系统。室内可见光通信技术将发光二极管(Light Emitting Diode, LED)发出的光作为信息传播的载体进行通信,该技术被称为“Lifi”,极有可能为室内短距离通信提供全新的解决方案。而对流层散射通信则是利用大气层中对流层对电磁波的散射实现远距离的非视距通信,常用于军事通信。针对室内可见光通信应用场景,本文建立了多径抽头时延信道模型并通过测量得到信道系数,给出了信道的时域冲激响应曲线和幅频响应曲线。针对散射通信系统应用场景,通过信道特性分析和文献查阅,本文建立了时延功率谱大小呈指数衰减的瑞利衰落信道模型。均衡器在单载波通信系统中不可或缺的部分,本文从算法原理入手,介绍了时域最小均方误差均衡算法(Time Domain Minimum Mean Square Error Equalizer, TD-MMSEE),时域判决反馈均衡算法(Time Domain Decision Feedback Equalizer, TD-DFE),频域块迭代判决反馈均衡算法(Frequency Domain Iterative Block Decision Feedback Equalizer, FD-IBDFE)和时频域混合判决反馈均衡算法(Hybrid Decision Feedback Equalizer, H-DFE)的原理,并给出上述算法在可见光通信场景下和对流层散射通信场景下的误码率性能。结合信道特点和各算法的计算复杂度,本文为可见光通信设计了频域最小均方误差均衡系统接收方案,为散射通信系统设计了时频混合判决反馈均衡系统接收方案。根据迭代接收机的迭代思想,本文提出了基于硬干扰抵消和软干扰抵消的迭代判决反馈均衡算法。仿真结果表明,硬干扰抵消迭代判决反馈均衡算法在3/4码率条件下能获得0.2～0.3dB增益,在1/2码率条件下能获得0.7dB左右增益,而软干扰抵消迭代判决反馈均衡算法在3/4码率条件下能获得0.6～0.7dB增益,在1/2码率条件下能获得1.2～1.3dB增益,验证了算法的有效性。本文最后一章给出了室内可见光通信系统和对流层散射通信系统的硬件设计与实现。硬件平台采用Xilinx公司的ML605开发板。本章从系统框架入手,详细介绍了系统各个模块的设计原理和主要作用,散射通信系统采用正交相移键控(Quadrature Phase Shift Keying, QPSK)调制,系统时钟速率为115.2MHz,实际通信速率38.4Mbps,可见光通信的采用开关键控(On-Off Keying, OOK)调制,系统时钟速率为200MHz,实际通信速率100Mbps,上述两个系统中均可传输高清视频业务,验证了硬件设计的正确性。
[Abstract]:The multipath effect of wireless communication channel will cause inter-symbol interference (ISI) and then affect the communication quality. An important method to solve this problem is equalizer.In this paper, the design of equalizer in single carrier communication system is studied, including the equalization algorithm of time domain minimum mean square error criterion, frequency domain iterative decision feedback equalization algorithm and time-frequency mixed decision feedback equalization algorithm, etc.At the same time, a hardware system is designed for indoor visible light communication and tropospheric scattering communication.Indoor visible light communication technology uses light emitting diode (LED) as a carrier of information transmission. This technology is called "Lifi", which is likely to provide a new solution for indoor short-range communication.Tropospheric scattering communication, which is often used in military communications, uses the tropospheric scattering of electromagnetic waves in the atmosphere to realize long-range non-line-of-sight communication.In this paper, a multi-path tap time-delay channel model is established for indoor visible light communication applications. The channel coefficients are obtained by measurement, and the time-domain impulse response curves and amplitude-frequency response curves of the channel are given.In this paper, a Rayleigh fading channel model with exponential attenuation of time-delay power spectrum is established by analyzing the channel characteristics and consulting the literature for the application scene of scattering communication system.The equalizer is an indispensable part of a single carrier communication system.浠嬬粛浜嗘椂鍩熸渶灏忓潎鏂硅��宸�鍧囪　绠楁常�

本文编号：1703748