基于QPSK-OFDM系统的循环前缀长度优化设计

摘要

OFDM系统中循环前缀CP长度对通信系统误码率性能有一定影响.运用CP线性叠加的算法,综合分析系统功率损失与信息速率损失两个性能参数,基于误码率最低原则,对子载波调制为QPSK的OFDM系统CP长度进行了优化分析.仿真结果表明:随着CP长度线性叠加变大,在循环前缀长度占OFDM符号长度20豫左右处会有一个最低误码率值,该处CP长度为最优,此时系统抵抗多径干扰能力最强.%Different length of cyclic prefix influences BER performance in OFDM system. The system power loss and data rate lose has been comprehensively analyzed. An optimization designing method has been proposed based on the principle of minimum BER with cyclic prefix linear superposition method in a subcarrier for QPSK modulation technology. Simulation shows that:as the length of CP became longer by linear superposition,the performance of BER is reduced and then linear increased. When the length of CP is about 20 豫 of the OFDM symbol length,a minimum BER value will be generated,while the length of CP is optimal. Moreover,the system has the strongest ability to resist multipath interference.