滤波多音调制系统中的信道估计和均衡技术研究

【作者】 胡兰雨；

【导师】 高振明；

【作者基本信息】 山东大学 ， 通信与信息系统， 2006， 硕士

【摘要】 近几十年以来，随着半导体技术和计算机技术的不断发展，无线通信已经逐渐成为人类日常生活中不可缺少的组成部分。 在下一代通信系统中，传统的固定网络、Internet及无线移动网络将相互融合，形成一个宽带无线通信系统。在这种现代宽带无线通信系统中对数据速率的要求将超过几兆bps，这意味着数据传输时需要占用相当大的信道带宽且信道的时延扩展将大于一个传输符号的符号周期，因此如何在有限的带宽内高速可靠地传输信息是极为重要的。 作为一种新型高速的传输技术，多载波调制技术(MCM)被人们广泛的应用于现代无线通信系统中。该技术相对于其它调制技术的显著特点是通过串行数据的并行传输实现在多径信道中信息的有效传递。在频率选择性衰落信道中，MCM技术可以大幅度提高系统的误比特率(BER)性能，特别是在高速数据传输的场合。 在众多MCM的实现方法中，正交频分复用(OFDM)和滤波多音频调制(FMT)是最为典型的两种代表性技术。由于两种技术设计的出发点不同，OFDM和FMT被应用于不同的通信标准中。凭借其良好的抗符号间干扰能力和对信道时间弥散的鲁棒性，OFDM技术已被用于众多无线通信标准中，例如数字视频广播(DVB)、数字音频广播(DAB)及IEEE 802.11a等。然而由于OFDM存在频偏敏感性的缺点，在多普勒频移丰富，同步技术粗糙的环境中，FMT无疑是一个非常合理的选择。该技术以牺牲部分抗符号间干扰(ISI)能力为代价来换取系统抗信道间干扰(ICI)的性能。目前FMT技术已经在VDSL中得到了广泛的应用，表现出良好的特性。 FMT是基于滤波器组的多载波技术。该技术的主要特点是各子信道具有很高的频谱约束性，对系统频率偏差不敏感。FMT克服了OFDM易受频率偏差影响的弱点，但FMT系统需要引入子信道均衡技术来消除滤波器组的影响。我们主要研究FMT技术在无线环境中的应用。本课题的研究受到国家自然科学基金(60372029)的资助。更多还原

【Abstract】 Wireless communication has played a more and more important role in peoples’ daily life with the development of semiconductor and computer technologies in recent decades.The traditional fixed nets, the internet and the mobile nets will merge together to form a wireless broadband communication system in the next generation of communication systems.The demand on data rate in this broadband wireless communication system will exceed several Mbps, which means the delay time of the delayed waves will become greater than one symbol time and a larger bandwidth is needed. So it is important to transmit data over band limited channel in a high data rate reliably.As a new technique for high data rate transmission, MCM systems have been extensively used in high-speed data transmission applications. Their main characteristic over other modulation schemes is that they transmit data in parallel subcarriers across the channel. With MCM techniques, system performance in BER can be improved remarkably over frequency selective fading scenarios when high data rate is required.There are many approaches to carry out MCM, Orthogonal Frequency Division Multiplexing (OFDM) and Filtered MultiTone modulation (FMT) are two typical techqniues among them. Due to the different purpose of the two techniques, OFDM and FMT are employed in different communication standards. Because of the immunity to ISI and the robustness to the time dispersion of the channel, OFDM has been used in many communication criterions,such as digital video broadcasting (DVB), digital audio broadcasting (DAB), IEEE 802.11a and etc. For the disadvantage of OFDM, whereas, in sensitivity to frequency offset. FMT is an idea choice for communication in the environment with abundant Doppler frequency shift and coarse synchronization technique. More immunity to Inter Channel Interference (ICI) can be achieved by sacrificing the partly immunity to ISI in FMT. It has been widely used in wire communication standards, such as VHDL.Filtered Multitone (FMT) Modulation is a new multicarrier technology based on filter banks. In FMT system, the spectrum of each subchannel has a high level of spectral containment. So the inter-channel interference(ICI) is negligible compared with other noise, while it often appears in OFDM system because of its sensitivity to frequency offset. However, sub-channel equalization is needed in order to reduce the更多还原