基于译码前传的中继旋转准正交空时分组码

Constellations Rotation for Quasi-Orthogonal Space Time Block Code in Decoding-and-Forward Relay Networks

提出了基于译码前传的中继旋转准正交空时分组码(Space Time Block Code,STBC),设计了码率为1、发射天线数为4的旋转码,然后在中继端和接收端分别采用快速最大似然译码算法和成对译码算法进行译码,最后与未旋转和中继前旋转两种STBC分别进行仿真对比。结果表明:当BER=10-3时,BPSK调制下,所提STBC比未旋转STBC和中继前旋转STBC分别有1.9 d B和1 d B的增益;QPSK调制下,所提STBC比未旋转STBC和中继前旋转STBC分别有1.8 d B和0.9 d B的增益;8PSK调制下,所提STBC比未旋转STBC和中继前旋转STBC分别有1.3 d B和0.6 d B的增益;在相同SNR条件下,中继旋转STBC与中继未旋转STBC和中继前旋转STBC相比具有更低的误码率,可以改善系统系能;当SNR增加时,所提码字的误码率将降得更快。

A new kind of quasi-orthogonal space time block codes （STBC） through constellations rotation in decoding-and-forward relay networks is proposed. The new STBC with four transmit antennas with rate one is firstly designed. Then the fast maximum likelihood decoding algorithm and the pair-wise decoding algorithm are respectively adopted at the relay and the receiver. Finally, comparison of the new STBC with the un-rotational STBC and the rotational STBC before the relay is done. Simulation results indicate that the new STBC can provide a gain of 1.9dB/1.8dB/1.3dB and 1dB/0.9dB/0.6dB than the un-rotational and the rotational STBC before the relay at the given BER of 10-3 for BPSK/QPSK/8PSK in the condition of four transmit antennas and one receive antenna. The new STBC can improve bit-error-rate performance as compared with the un-rotational STBC and the rotational STBC before the relay under the condition of same SNR. When the SNR increases, the BER of the new STBC reduces faster than that of the non-rotational STBC and the rotational STBC before the relay.