典型水声多径信道下CP对OFDM系统性能的影响

Effects of CP on OFDM System Performance in Typical Underwater Acoustic Multipath Channels

为了完全消除系统中由多径效应带来的干扰,可在符号间设置循环前缀(CP)作为保护间隔(GI)。针对CP消除多径干扰的原理,对典型水声多径信道下设置CP时的OFDM系统性能进行探究。在OFDM系统中采用二进制相移键控(BPSK)调制技术,以误码率和信息传输速率作为系统性能衡量标准,验证了CP降低系统误码率的作用,同时得到信息速率损失与CP长度呈正相关,由仿真结果得出CP对系统可靠性产生影响的条件为TCP<τmax,为OFDM系统中CP的最优选取提供依据。

In order to completely eliminate the interference caused by multipath effect in Orthogonal Frequency Division Multiplexing(OFDM) system, cyclic prefix(CP) can be set between symbols as guard interval(GI). In consideration of the principle of CP’s eliminating multipath interference, the OFDM system performance with CP in typical underwater acoustic multipath channel is investigated with Binary Phase Shift Keying(BPSK) modulation technology used in the OFDM system. Bit error rate and information transmission rate are taken as system performance measure, verifying the role of CP in lowering the BER of the system as well as finding that the information loss rate is positively correlated with the length of CP. According to the simulation results, the condition that CP has impact on the reliability of the system is TCP<τmax, which provides a basis for optimal selection of CP in OFDM system.