滤波多音调制系统中峰值平均功率比的研究

【作者】 李志勇；

【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，而大量的用户需求反过来又促进了无线通信的发展。 随着声音、图像和数据通信业务在互联网和无线通信中的快速增长，对下一代通信系统的定义成为新的研究热点。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Mbit／s，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。研究表明，如果多径信道的时延扩展(信道记忆长度)远小于一个传输符号的符号周期，则由多径传播造成的符号间干扰可以忽略不计。所以，可以利用多载波传输技术在不降低信息传输速率的条件下使信道中的传输符号的符号周期远大于多径信道的时延扩展，从而可以有效地对抗由多径传播造成的ISI。 正交频分复用(OFDM)技术是当今通信技术研究中的一个热点。作为一种多载波技术，它具有抗多径干扰能力强、频谱利用率高等优点。然而OFDM技术也存在着一些缺点，如容易受频率偏移影响、符号同步困难等，这些问题都制约着OFDM在无线信道中的应用[1]。 滤波多音频(FMT)技术相对于OFDM是一种新兴的多载波技术。该技术的主要特点是各子载波具有很高的频谱约束性，对系统频率偏差不敏感。FMT技术克服了OFDM技术易受频率偏差影响的问题，但是其滤波器组在系统中引入了ISI，因此，FMT中需要引入了信道均衡技术来消除滤波器组的影响。本课题的研究受到国家自然科学基金(60372029)的资助。 FMT系统的一个主要缺点就是峰值功率与平均功率比(PAPR)过高。相对单载波系统而言，FMT输出信号是由多个子信道信号叠加而成，因此系统发射机的输出信号的瞬时值会有较大的波动。如果发射机的动态范围不能满足信号的变化，则会造成信号畸变，使叠加信号的频谱发生变化，产生相互干扰，使系统性能恶化。因此，如何有效地降低FMT系统PAPR就显得非常重要。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, which in turn promote the rapid expansion of the wireless communication.The definition of the next generation of mobile communication is the new emphasis of research with the rapid increase in sound, image and data communications over the internet and wireless. 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. The effect of the ISI is negligible so long as the delay spread of the multi-path channel is significantly shorter than the duration of one transmitted symbol. Therefore, multicarrier transmission technology can be used to overcome this limitation.Nowadays, Orthogonal Frequency Division Multiplexing (OFDM) is a key technology in the mobile communication field. As one of the multi-carrier transmission technologies, OFDM can reduce the multipath fading effect with high frequency efficiency. However there are some disadvantages in OFDM system such as sensitivity to frequency offset, symbol synchronization and so on. All of these limit the application of OFDM in wireless environment.Filtered Multitone (FMT) Modulation is a new multicarrier technology in contrast to OFDM. In FMT system, the spectrum of each subchannel has a high level of spectral containment. So the Inter-channel Interference (ICI) of FMT is negligible compared to other noise, while it often appears in OFDM system because of its sensitivity to frequency offset. However, subchannel equalization is needed in order to reduce the remaining ISI introduced by the filter banks.One disadvantage of FMT system is that the peak transmitted power can更多还原