MIMO论文：2x2 MIMO-OFDM实时平台设计与开发.doc

MIMO论文：2x2 MIMO-OFDM实时平台设计与开发【中文摘要】近两年来,3G体系在中国已经趋于成熟发展,后3G技术成为众多研究人员的关注热点,并且无线通信委员会最近公开了能够提供宽带数据服务的技术,例如：多媒体流、高清电视等。因此,后3G系统的发展方向为高速率通信系统,需要协调解决吞吐量、覆盖率和可靠性三个方面的需求。多输入多输出技术是通过空间多分复用来普遍用于提高通信可靠性和提高数据吞吐量的。正交频分复用技术已经被认为是多径衰落环境中通过接收端使用简单的均衡技术接收信号最有效的方法之一。MIMO-OFDM系统结合了这两种技术,吸引了当今无线通信领域的关注。IEEE802.11n标准支持MIMO-OFDM某一特定模式；IEEE802.11ae任务组已经开始了建立下一代WLAN标准,带宽在6Gbps以下,吞吐量目标是MAC层达到1GbpS。综上所述,对MIMO-OFDM技术的研究在通信界已经炙手可热。然而MIMO-OFDM的性能只是在理论和仿真级上被证明,对于其硬件实现仍然存在一定的挑战性。目前,国内外越来越多的研究机构和大学开始进行MIMO-OFDM平台的设计、开发与验证。在各种国际会议和期刊中,相关的论文也频频出现。然而对于如何建立一个具有通用性、可扩展性、可靠实时传输和实时验证的平台,却没有定论。完全软件实现MIMO-OFDM平台,虽然具有设计周期短,易于实现等优点,但是却缺乏验证平台的最初的出发点在实际环境中实时测试MIMO-OFDM技术的性能；完全硬件实现MIMO-OFDM平台,克服了完全软件设计的缺点,但对比而言,挑战,如设计开发周期长、可扩展性差和算法修改实现困难；二者折中,可以兼具两者优点,但是软硬件结合设计的平台,移植到硬件实施的结果还未可预测。在MIMO-OFDM验证平台设计标准各不相同的情况下,如何设计出可以具有上述优点,也可以克服相应缺点,并且能够展现各自特色的MIMO-OFDM实时平台,成为越来越多的研究工作人员的开发目标。基于以上考虑,本文提出基于硬件实现的,实时性高的多输入多输出多载波(MIMO-OFDM, Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing)无线通信系统验证平台,目标在于研究真实无线信道环境下,MIMO-OFDM技术的可实现性和性能问题。该平台主要基于FPGA实现,具有模块化、实时性、可验证功能,信号基带处理和中频处理完全自主研发,模拟数字转换器和射频天线模块采用商业化产品,其在于降低开发周期,避免现在已经成熟的技术的不必要二次开发。本2x2MIMO-OFDM验证平台可以用于教学、科研与商业合作等方面,也可以用于最新MIMO-OFDM技术最新研究技术的实现与功能验证。文章最后介绍了现已实现的基于IEEE802.11n标准的2x2MIMO-OFDM实时平台的实验结果。【英文摘要】Recently,3G systems have been more and more mature in China. Now, the beyond 3G technologies have been focused by more and more researchers and wireless communication committee has opened the technique which can supply the wide band data service, such as Multi-media stream, High Definition Television, etc. Therefore, the direction of the beyond 3G system is to be high-rate communication systems and to handle the need in three aspects:throughput, cover rate and reliability.A Multi-input multi-output (MIMO) technique is commonly used to improve communication reliability or increase data throughput by spatial multiplexing. Orthogonal division frequency multiplexing (OFDM) has been known as a powerful technique in equalizing received signals under multipath fading environments. A MIMO-OFDM system, given by combing these two techniques, attracts a great deal of attention in current wireless communications. The IEEE 802.11n standard supports MIMO-OFDM in mandatory mode. Meanwhile, the IEEE802.16ac task group has started to establish a next-generation WLAN standard below 6-GHz band. And the throughput target is 1 Gbps at MAC layer. In conclusion, the research in MIMO-OFDM technique has been a hot point in wireless communication field. However, the performance of MIMO-OFDM technique just can be proved in theoretical and simulation and there are still challenges in hardware implementation.Nowadays, more and more research organizations and institutes begin to design, develop and verify the possibility of MIMO-OFDM platforms at home and abroad. Related papers have been frequently published in various international workshops and journals. But, how to develop a platform which has generality, expandability and reliability of real-time transmission is still a question. To design a MIMO-OFDM testbed completely using software can not only decrease the design period but also be implemented easily except evaluating the performance of MIMO-OFDM technique in real wireless environment which is the key point of constructing platforms; implementing MIMO-OFDM testbed entirely using hardware can conquer the shortcomings of software, but this method has long developing period, bad expandability and slow algorithms renewal compared with software implementation; we can find a tradeoff way-software and hardware co-design, which can collect the advantages of the two above ways and conquer the disadvantages of them. Moreover, it is also thought as the develop target of researchers.Regarding to the above aspects, in this paper, we propose a MIMO-OFDM real-time platform which was based on hardware to assess the implementation possibility and performance of MIMO-OFDM techniques in real wireless channel. It has modularity, real-time, easy to evaluation and other features. In this platform, we design and develop baseband and IF processing by ourselves, but we decide to buy the ADC/DAC, RF modules and antenna array in order to decrease the developing period. This 2x2 MIMO-OFDM can be utilized in education, researching and industry, and to a higher degree, used to implement and assess the latest MIMO-OFDM algorithms. Finally, we introduce some results based on the 2x2 MIMO-OFDM real-time platform based on IEEE 802.11n standard.【关键词】MIMO OFDM 实时平台 验证【英文关键词】MIMO OFDM real-time platform verification【目录】2x2 MIMO-OFDM实时平台设计与开发目录4-6CONTENT6-8摘要8-10ABSTRACT10-11符号说明12-14第一章 绪论14-211.1 引言14-151.2 MIMO-OFDM实时平台国内外研究与发展现状15-181.2.1 MIMO-OFDM实时平台国外研究与发展现状16-181.2.2 MIMO-OFDM实时平台国内研究与发展现状181.3 本课题来源及所做的工作18-201.4 论文结构20-21第二章 MIMO-OFDM系统关键技术研究21-322.1 空时编码理论21-242.1.1 空时分组码21-232.1.2 空时网格码23-242.2 调制与解调24-262.2.1 硬判决解调252.2.2 软判决解调25-262.3 定时与载波频偏估计26-272.3.1 帧同步检测26-272.3.2 载波频偏估计272.4 数字上下变频27-322.4.1 采样定理282.4.2 多速率数字信号处理28-292.4.3 滤波器设计29-32第三章 2x2 MIMO-OFDM实时平台硬件结构32-413.1 2x2 MIMO-OFDM实时系统整体架构32-333.2 基频及中频收发机描述33-383.2.1 基频及中频发送SMT310Q+SMT365+SMT368+SMT35034-363.2.2 基频及中频接收SMT310Q+SMT395+SMT368+SMT35036-383.3 射频收发机描述38-403.4 PC机40-41第四章 基于IEEE802.11n的2x2 MIMO-OFDM实时平台设计与开发41-624.1 IEEE802.11n协议综述41-434.2 MIMO-OFDM符号表示43-454.3 2x2 Alamouti空时编码方案45-48