中文摘要：

提出了四副发射天线时的酉空时编码新方案,通过合并单位阵和空时分组编码矩阵,将接收端的最大似然译码简化为最大欧氏距离译码,从而大大降低了译码复杂度;根据瑞利衰落下的接收信噪比,推导出了信道容量下界.分析和仿真结果表明,该方案能够保证满分集增益,在误码性能接近最大似然译码的同时,译码时复数运算次数降低了85.6%,且信道容量下界与理论推导相一致.

英文摘要：

The new encoding algorithm for the unitary space-time scheme with four transmit antennas is proposed.By combining the unit matrix with the space-time block code matrix,maximum likelihood decoding at the receiver is simplified to maximum Euclidean distance decoding so that complexity for decoding is reduced greatly.On the basis of analysis on the receive SNR in the Rayleigh channel,the lower bound of the capacity is deduced.Analysis and simulation results show that full diversity gain is guaranteed by the scheme,the number of times of complex number calculation for decoding is reduced by 85.6% while the bit error rate of this scheme is approximate to that of the maximum likelihood decoding algorithm.And the lower bound of channel capacity coincides with the one deduced theoretically.