NC-OFDM的PAPR统计特性分析

NC-OFDM(Non-contiguous OFDM)是基于OFDM的频谱池技术,它是认知无线电主要的数据传输方式,系统地分析了NC-OFDM信号的峰均比(PAPR),由于OFDM信号的PAPR取决于一个符号周期内数据的非周期相关特性,因此推导出NC-OFDM信号的相关函数,并用相关系数对相关性进行度量,提出了当信号的相关系数小于0.08这个门限时,可以近似认为信号不相关,并可以用公式计算PAPR的CCDF。仿真结果证明,当总的子载波个数小于8192,可用子载波个数大于128时,其相关系数都在0.08以下,都可以用公式求其PAPR。

Statistical Properties of PAPR for NC-OFDM Signals

As a spectrum pooling technology based on OFDM, non-Contiguous OFDM is a main approach of data transmission of cognitive radio. The peak-to-average ratio （PAPR） of the NC-OFDM is systemically analyzed in this paper. Since PAPR of the OFDM signal is determined by aperiodic correlation property of the data in one symbol period, the correlation function of the NC-OFDM symbol, therefore, is derived in the paper. Moreover, the correlation is measured by correlation coefficient. The conclusion is drawn that the signal is approximately considered to be noncorrelated and the CCDF of PAPR can be calculated by formula when the correlation coefficient of the signal is below the threshold value of 0. 08. Simulation results prove that the correlation coefficient is below 0.08 and can be calculated by formula when the total number of subcarriers is below 8192 and the number of active subcarriers is above 128.