利用格雷互补序列降低多载波CDMA信号的峰平比

Reducing Peak-to-Average Power Ratio of Multicarrier CDMA Signals with Golay Complementary Sequences

多载波 CDMA信号峰平比比较高 ,影响到功放的功率效率 ,这已经成为限制多载波 CDMA技术应用的一个关键因素。本文分析表明 ,多载波 CDMA信号的峰平比与编码序列频谱幅度特性有关 ,采用格雷互补序列(Golay complementary sequences)能有效降低信号的峰平比。数值分析和仿真结果表明 ,对于任意长度格雷互补序列的多载波信号 ,其峰平比上限为 6d B,并且峰平比随序列长度的变化波动很小。而长度为 1 5 ,3 1 ,63的 m序列多载波信号的峰平比分别为 9.47,1 2和 1 5 .0 6d B,并随序列长度的增加而增加。格雷互补序列多载波信号的峰平比性能明显优于

Capacity and performance of mobile radio systems essentially depend on the choice of the multiple access scheme. A novel and promising wireless multiple access technique called multicarrier code division multiple access (MC-CDMA) is studied, including reducing peak-to-average power ratio in multic systems. MC-CDMA is combination of orthogonal frequency division multiplexing (OFDM) and CDMA, thus advantages of both techniques are exploited, and has good foreground in personal communication services (PCS) and 3G mobile communication in future for its advantages. The ratio of peak and average power in multicarrier system is much larger than in single carrier system, and may grow unboundedly as the number of subcarriers grows. The high peak-to-average ratio of signals may decrease efficiency of power amplifier, and has become an obstacle to utilities of multicarrier systems. This paper studies behaviors of multicarrier CDMA systems with Golay complementary sequences. Performance analysis and simulation indicates that the peak-to-average ratio of a multicarrier CDMA signal with arbitrary carriers can be reduced no more than 6 dB by using Golay complementry sequences and S-R sequences as spreading sequences, which is much superior to m sequences in performance of the peak-to-average ratio.