滚降系数不匹配对MQAM解调性能影响

Effects of Mismatched Roll-off Factor on Demodulation Performance of MQAM Signal

在非协作通信中,发送端的滚降系数对于接收方是未知的。为了能够对接收信号进行正确解调,接收方必须从观测数据中估计出这个参数。因此研究滚降系数误差对QAM系统的影响,具有重要意义。文中仿真分析了在接收端无处理和采用符号定时恢复两种情况下根升余弦滤波器滚降系数不匹配对接收性能的影响,测试结果表明此影响很小,在未知发端滚降系数的情况下,收端滚降系数设置为0.5～0.7,对接收性能的影响最小。这一结论在非协作通信中具有重要意义。

In non-cooperative communication systems,the roll-off factor of the transmitter is unknown for the receiver.In order to demodulate the signal correctly,the receiver must estimate this parameter from the observed data.So it is of great significance to investigate the effects of roll-off factor error on the QAM system.This paper,based on the simulation,analyzes the effects of roll-off factor error on the performance of the receiver with symbol timing recovery and without processing.The results show that the effect is very small.It is reasonable to set the receiving roll-off factor to be 0.5-0.7 without knowing the transmitting roll-off factor,and thus it is of the smallest impact on receiving performance.This conclusion is very important in non-cooperative communication.