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正交频分复用系统抑制峰均比技术的分析与研究
Research on Peak-to-Average Power Ratio Reduction for OFDM Systems
【作者】 汪锦洲；
【导师】 余立建；
【作者基本信息】 西南交通大学 ， 计算机应用技术， 2009， 硕士
【摘要】 正交频分复用(OFDM)技术被当今社会普遍认为是4G的核心技术之一。目前已经被应用于无线局域网(WLAN:Wireless Local Area Networks),无线城域网(WMAN:Wireless Metropolitan Area Networks),数字视频广播和数字音频广播等领域。作为多载波系统的一种,OFDM系统和其它的多载波传输系统一样,同样存在峰均比(PAPR:Peak to Average Power Ratio)过高的问题,容易导致OFDM信号失真,系统性能下降等问题,限制了OFDM技术的实际应用。因此,对抑制OFDM信号的PAPR研究显得尤其重要。本文首先阐述了OFDM技术的应用现状,简单介绍了OFDM技术的基本原理,对OFDM技术的高峰均功率比问题进行了描述,高峰均比对系统产生的危害进行了分析。其次,对当前抑制OFDM信号峰均比的多种算法进行了研究,并对经典的算法进行了仿真分析。通过对各种方法的研究,归纳总结出各种方法的特点。最后,考虑到单独使用一种方法,总会有或多或少的缺点,本文以混合使用抑制OFDM技术PAPR的算法为出发点,将特定的几种互补算法按照一定结构结合在一起,研究得出这种混合算法能有效地平衡算法的误码率,峰均比,复杂度等性能,使之能符合实际系统需要。文章还研究了次优化搜索PTS算法,从同等复杂度的角度来比较各种次优PTS算法的PAPR性能,分析得出几种算法性能相近。文章最后通过级联预LC-TR算法,对迭代翻转PTS算法进行了优化。
【Abstract】 Recently, orthogonal frequency division multiplexing (OFDM) has been regarded and used as one of the core technologies for 4G Mobile Communication System. It has been adopted for various wireless communication systems such as wireless local area networks (WLANs), wireless metropolitan area networks (WMANs), digital audio broadcasting (DVB). As one of multi-carrier communication systems, OFDM also suffers from the problem of high Peak to Average Power Ratio (PAPR), which causes the signal distortion, the degradation of system performance and the restrictions on the use of the system. Thus, the PAPR reduction is one of the most important research interests for the OFDM systems.Firstly, in the article, the basic theory of OFDM is explained. Besides, we describe the PAPR of OFDM systems, and the crisis which caused by PAPR for the system is proposed.Secondly, the article focuses on the research of the various approaches to reduce the PAPR of OFDM signals, and the simulation of some traditional schemes is given in this paper. Besides, we summarize the PAPR reduction techniques based on analysis.In the end, we found it is difficult to resolve the PAPR by using one scheme separately. Based on hybrid, combined several special methods would have better PAPR performance. In simulation results, the hybrid method shows the balance on PAPR, complexity and bit errors rate performance of OFDM system. Besides, we also research on low-complexity PTS, and compare the PAPR performance of these schemes at the same complexity. In simulation results, we found they have similar PAPR performance. Finally, we research on cascade algorithm of LC-TR and IPTS.