OFDM系统中的峰值平均包络功率比上下界的分析

Analysis of Upper and Lower Bound on Peak-to-mean Envelope Power Ratio in OFDM Systems

本文主要对OFDM系统中的峰值平均包络功率比(PMEPR)的上下界进行了推导.推导结果表明,PMEPR的上界仅和数据序列的非周期自相关函数有关,这对于迅速去除PMEPR超过给定门限的数据序列是非常有用的.从推导的PMEPR下界看,只有当子载波数N很少时,它才会随N变化较大.针对一个16子载波的BPSK OFDM系统,本文借助于PMEPR的上界还对一种降低PMEPR的选择性映射技术进行了分析,并给出了所有可能信息序列的PMEPR分布.分析结果表明,最大PMEPR约为6.5dB,比最坏情况下的PMEPR减少了5.5dB.

Upper and lower bounds on peak-to-mean envelope power ratio (PMEPR) in OFDM systems are derived in this paper.The derivation results show that the upper bound onPMEPR only depends on the aperiodic autocorrelation functions of the data sequences and is quite useful for rapid elimination of sequences that havePMEPR exceeding a given threshold. According to the lower bound onPMEPR,it has a great change asN (number of subcarriers) varies only for a very smallN.For a 16-subcarrier BPSK-OFDM system, a selective mapping (SLM) way to reducePMEPR is investigated with the upper bound onPMEPR and the distribution ofPMEPR for all possible message sequences is given.The analytic results show that the maximalPMEPR is about 6.5 dB which is 5.5 dB less than that in worst situation.