快衰落信道中的分布式差分空时编码传输方案

A Coding Transmission Scheme with Distributed DifferentialSpace-Time for Fast Fading Channels

针对分布式差分空时编码(DDSTC)在时间选择性快衰落信道中出现误码率平台的问题,提出了一种新的有效减小信号帧长的DDSTC传输方案(RFL-DDSTC)来抵抗快衰落信道的影响.该方案在中继节点处通过采用T个正交向量,将DDSTC在T个符号周期内的信号合并到1个符号周期内进行转发,使得DDSTC信号变为具有单位帧长的短信号.在目的节点,再对合并后的RFL-DDSTC信号用T个正交向量进行解调,即可还原出原始的DDSTC信号.该方案由于大大缩短了DDSTC信号的帧长,因而可以有效减小信道快衰落带来的不利影响,显著地降低了DDSTC性能曲线中的平台.仿真结果表明,在发射功率为30dB时,RFL-DDSTC方案可将DDSTC的误码率平台降低一个数量级以上.

A new DDSTC scheme with reduced frame length,named as RFL-DDSTC,is proposed to solve the problem that the performance of distributed differential space-time coding（DDSTC） suffers from an irreducible error floor in time-selective fast fading channels.The proposed RFL-DDSTC scheme uses T orthogonal vectors at relay nodes to combine the DDSTC signals in T symbol periods into one symbol period so that DDSTC can be turned into a shorter signal with unit length Then,the T orthogonal vectors are used at the destination node to demodulate the compressed RFL-DDSTC signals,and the original DDSTC signals are resumed.Since the frame length of DDSTC is greatly reduced,the proposed RFL-DDSTC is highly effective in mitigating the impact of channel fast fading on its performance,and the performance error floor has degraded significantly.Simulation results show that RFL-DDSTC can degrade the error floor of DDSTC for more than ten times at 30 dB.