滤波多音调制（FMT）在WLAN环境下的技术研究

【作者】 朱维红；

【导师】 高振明；

【作者基本信息】 山东大学 ， 通信与信息系统， 2006， 博士

【摘要】 为实现未来移动通信的高速宽带和可靠传输，以正交频分复用(OFDM)为代表的多载波调制(MC)技术，因其良好的抗多径能力和克服码间干扰(ISI)的能力而获得了深入研究和广泛应用，其中OFDM已经被多个标准采用，并作为第四代宽带移动通信(4G)系统的备选关键技术之一。但是OFDM也存在一些内在缺点，如它的正交性在传输中易受破坏，从而需要大量的开销(循环前缀(CP)和虚载波等)、较为严格的现载波与定时同步等来保证系统性能。针对OFDM的这些缺点，本文研究了一种新的多载波调制技术——滤波多音调制(FMT)技术及其在无线通信中的应用。 滤波多音调制是基于滤波器组(filter banks)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，从而克服了OFDM易受频率偏差影响的弱点。但由于采用了不满足理想重构条件的有限冲激响应(FIR)滤波器作为子信道滤波器，FMT系统引入了码间干扰(ISI)，因此系统接收端需要引入子信道均衡技术，以消除滤波器组的影响。 本文系统介绍了FMT基本概念。由于FMT是基于滤波器组调制的技术，因此我们从多采样率数字信号处理和滤波器组技术的角度，对FMT的基本概念进行了描述，给出了严格采样FMT系统和非严格采样FMT系统的有效实现形式。 在FMT系统中，影响系统性能的关键参数是原形滤波器的性能。本文对FMT系统滤波器组的设计进行了系统的研究。由于FMT系统性能与滤波器组的性能息息相关，因此滤波器组的设计成为FMT技术的关键之一。根据FMT的特点，本文提出FMT系统中滤波器组设计的几项性能指标，给出满足这些指标的滤波器设计方法和实例，同时创新性地提出了一种优化的FMT原型滤波器的设计方案。仿真试验表明，采用该准则设计出的原形滤波器与其他方法相比具有较高的可达比特率和较好的误比特率性能。 系统均衡器的设计。因为FMT系统是采用频带严格受限的滤波器组实现的，因此不可避免地引入了ISI，而有效克服ISI的方式是均衡技术。本文根据FMT的特点提出不同的均衡方案，并通过仿真实验比较它们的性能，提出不同环境，不同要求下的不同的均衡方案，同时研究了基于辅助数据均衡(DAE)技术，创新提出了结合因子图的DAE二次判决算法，将其应用于FMT中，取得了良好的均更多还原

【Abstract】 Multicarrier modulation technique has recently evoked considerable interests and widespread applications for its attractive qualities in resisting multi-path effects and mitigating ISI. Taken as an example, the OFDM technique has been adopted for some formed standards and even regarded as a candidate for the coming 4G-wideband mobile communication systems. However, OFDM has some intrinsic shortcomings: its orthogonality is susceptible to be destroyed in practical transmission, thus considerable overheads (CP and virtual carriers), strict synchronization and etc. are needed. In order to avoid these disadvantages of OFDM, a new multicarrier modulation technique, named Filtered Multitone Modulation (FMT) is studied for its applications in wireless communication in this thesis, with some related aspects being investigated intensively.FMT is also a multicarrier modulation technique based on filter bank technology. The main character of this technique is the high-spectral constraint of each subcarrier which results in its non-sensitivity to frequency offset where OFDM enduring. However, FMT has inter-symbol interferences (ISI) which are caused by the non-ideal subchannel filters. ISI has to be eliminated by per-subchannel equalizers.Firstly, we introduced the basic concept and efficient realization of FMT system in this dissertation. FMT belongs to filter bank technology. Thus we give description of FMT system based on multirate signal processing and filter banks. Efficient realizations of both critically sampling system and non-critically sampling system are deduced.Secondly, we analyze how to design the filter bank or equavently the prototype filter. For FMT system, one of the most important coefficients is the prototype filter. Its performance affects the performance of the overall system directly. Thus, we first give the design requirements of the prototype filter. Then, we give some examples which could satisfy these requirements. Finally, we deliver a scheme on optimizing the prototype filter. Simulation results show that optimum prototype filter could achieve better error probability performance and achievable bit rates.Third, we consider how to design the subcarrier equalizers. FMT system should add subcarrier equalizers at the output of the receiver to compensate ISI introduced by更多还原