正交频分复用码分多址信号峰均功率比特性的研究  

Study on Peak-to-Average Power Ratio for Orthogonal Frequency Division Multiplexing Code Division Multiple Access Signal

作　　者：李巍[1] 邓建国[1] 

机构地区：[1]西安交通大学电子与信息工程学院,西安710049

出　　处：《西安交通大学学报》2004年第10期1085-1089,共5页Journal of Xi'an Jiaotong University

基　　金：国家自然科学基金资助项目 (60 0 72 0 40 );教育部高等学校博士学科点专项科研基金资助项目 (2 0 0 2 0 6980 2 8)

摘　　要：针对正交频分复用码分多址(OFDM CDMA)信号的峰均功率比值(PAPR)较大的问题,从分析OFDM CDMA信号模型入手,提出了在理想情况下信号PAPR的累积分布概率表达式,指出了信号PAPR的累积分布概率与PAPR门限值之间存在负指数关系,为深入分析影响PAPR特性的因素提供了参考标准.采用信号包络分析法,发现了信号功率表达式中存在时频变换关系.研究发现:采用相关特性较好的伪随机扩频序列能够改善信号的PAPR特性;不同的数字调制方式对信号的PAPR特性没有影响;用户数量较多的系统的PAPR值较小.仿真结果表明,在系统参数相同的条件下使用正交平衡Gold码比使用Walsh码得到的PAPR值至少减小2～3dB,同时增加系统中的用户数量也能够明显改善信号的PAPR特性.Focused on the problem that orthogonal frequency division multiplexing code division multiple access(OFDM-CDMA) signal has a large peak-to-average power ratio(PAPR), the model of OFDM-CDMA signal was analyzed firstly and then the theoretical expression of the PAPR cumulative distribution probability of the ideal signal was proposed. The expression indicated the negative exponential relationship between the PAPR cumulative distribution probability and the PAPR threshold, and it could be the basis to analyze the factors affecting the signal PAPR property. Furthermore, based on the analysis of the signal envelope power and the discovery of the time-frequency relationship in the envelope power expression, the factors affecting the PAPR property of the signal were studied, and the following conclusions were reached: the PAPR property of OFDM-CDMA signal could be improved by taking the spreading codes with good correlation property, but had nothing to do with the type of digital modulation schemes. And it was also concluded that the PAPR of the lightly loaded system was larger than that of the fully loaded system. Simulation results demonstrated the validity of the conclusions of the theoretical analysis.

关 键 词：正交频分复用码分多址 峰均功率比 信号功率 扩频序列 数字调制方式 OFDM-CDMA 

分 类 号：TN911[电子电信—通信与信息系统]