可获得满分集增益的正交线性分散空时编码

Novel Orthogonal Linear Dispersion Space-Time Codes Achieving Full Diversity Order

针对多输入多输出系统中现有的线性分散(LD)空时码编、解码复杂度高的问题,提出了一类正交线性分散(OLD)空时编码.OLD码与LD码搜索最优基矩阵的方法不同,它采用一组各列相互正交的随机基矩阵对要传输的数据符号进行空、时二维上的调制,不仅对任意发射天线数都可以获得满分集增益,而且在最大似然解码时可以完全解耦各数据符号,大大简化了发射机和接收机的设计,改善了系统性能.理论分析及仿真实验表明,当发射天线数与数据符号数的乘积小于等于空时编码的帧长时,OLD码获得了比LD码更大的信道容量,并且由于OLD码在解码的过程中可以完全消除符号间的干扰,因此在相同误码率条件下比LD码的信噪比提高了2dB.

Focusing on the problem that existing linear dispersion （LD） space-time codes have a high encoding and decoding complexity, a type of orthogonal linear dispersion （OLD） space-time codes is proposed.Differing from the LD codes which need to search for the optimal basis matrices, the OLD codes use a set of columns of orthogonal random basis matrices to modulate the information symbols in both spatial and temporal dimensions. For any number of transmit antennas the OLD codes not only achieve the full diversity order, but also fully decouple the data symbols when the maximum likelihood decoding is employed.Hence, the designs of the transmitter and receiver are simplified and the performance is improved. Theoretical analysis and simulation results show that the OLD codes outperform the LD codes in terms of channel capacity when the product of the number of transmit antennas and the number of data symbols is less than or equal to the frame length of the space-time codes. Moreover, the signal noise ratio of the OLD codes is superior to that of the LD codes by 2 dE at the same bit error rate owing to the elimination of the interferences among the symbols.