被动时反与自适应均衡相联合的水声通信研究

A study of underwater acoustic communication based on the joint processing of passive time reversal and adaptive equalization

在实际的水声环境中,被动时反处理单向传输、实施简单,可以减小信道衰落的影响并重组多途信号,抑制码间干扰,但因水声信道复杂性等的影响,接收到信号经被动时反处理后仍存在残余的码间干扰,为此,被动时反处理后,基于递归最小二乘(RLS)的判决反馈自适应均衡处理方法被用来消除这些残余的码间干扰。复杂的实验室波导试验结果表明这种联合处理:(1)实现了无误码传输,(2)自适应均衡器的抽头数较少,计算复杂度较低。验证了被动时间反转和自适应均衡相联合的信号处理方法在相位相干水下通信中的可靠性与高效性。

Passive time reversal processing only needs one-way propagation so that it can be implemented more easily.While its spatial focusing can mitigates channel fading and its temporal focusing reduces intersymbol interference（ISI）,there always is some residual ISI depending on the complexity of the channel.Therefore a decision feedback equalizer based on recursive least squares algorithm is used to reduce the residual ISI after passive time reversal processing.The complex experimental waveguide results show that（1） the number of error symbols can be reduced to zero by this joint processing while it＇s impossible for the passive time reversal processing;（2） the number of taps of adaptive equalization after passive time reversal processing is reduced largely so that the complexity of computation is also reduced.This demonstrates that this joint processing of passive time reversal and adaptive equalization is not only reliable but also effective in phase coherent underwater communication.