时域均衡在OFDM水声通信系统中的应用

Application of Time-domain Equalizer in OFDM Underwater Acoustic Communication System

为了对抗水声信道时延扩展大于循环前缀长度时引起的码间串扰问题,在基本的OFDM水声通信系统接收端进行DFT变换前加入相对较短的时域均衡器来限制信道冲激响应的长度。分析了基于MMSE准则的时域均衡算法的实现过程以及算法的复杂程度,对该算法在水声环境下的性能进行了仿真分析,并比较了影响系统性能的因素。结果表明通过加入时域均衡器能够有效对抗信道严重的时间离散性,改善OFDM水声通信系统在循环前缀不足时的系统性能。

In order to overcome the inter-symbol interference due to delay spread larger than the length of cyclic prefix,a shorter time-domain equalizer is added before DFT in basic OFDM underwater acoustic communication system to limit the length of the channel impulse response.The process of implementation and the complexity of the time-domain equalization algorithm based on MMSE criteria are analyzed.The performance of this algorithm in underwater acoustic conditions is simulated and the elements are compared that can affect the performance.The simulation results show that the time-domain equalizer can overcome the severe time-dispersion of the channel and improve the performance of OFDM underwater acoustic communication system effectively when the length of cyclic prefix is not enough.