相关瑞利信道环境下空时编码系统性能分析

Performance analysis of space-time coding system for correlated Rayleigh fading channels

主要研究了空时编码系统在相关瑞利衰落信道和高斯噪声环境下的性能。基于Karhunen Loeve去相关变换,将相关的系统子信道系数向量投影到另一组元素间不相关的系数向量。根据所得的去相关的系数向量,得到了系统误码率的解析表达式。同时,将误码率公式表示为有利于数值计算的一元有限积分形式,推广了熟知的不相关瑞利衰落环境下的系统误码率公式。对所得理论结果进行数值仿真,结果表明相关性使系统编码增益降低1～2dB。

The performance of space-time channel coding scheme is discussed under a Rayleigh fading channel with spatially correlated fading amplitudes and an additive white Gaussian noise. The correlated fading amplitudes vector is mapped to an uncorrelated one by the Karhunen-Loeve transform. Thus a closed-form formula on the bit error rate is obtained basing on the uncorrelated coefficients. Meanwhile, the bit error probability can be expressed by an integral over a finite interval, which can be easily evaluated numerically. So we generalize the well-known analytical expressions for the bit error probability of the uncorrelated Rayleigh channel to the case of correlated fading one. Numerical results demonstrate the correlation among the transmission path decreases the coding gain of the system 1-2 dB.