非理想信道估计和相关Nakagami信道条件下空时发送分集的性能分析

深入分析了非理想信道估计和相关Nakagami衰落2种因素对空时发射分集系统性能的影响.首先在高斯信道估计误差的假设条件下,得出了空时发射分集(STTD)接收信号的信噪比公式.在具有任意衰落相关矩阵的相关Nakagami信道条件下,推导出空时发射分集系统误比特率公式.最后通过蒙特卡罗仿真所得结果与理论误比特率相比较,证明了文中所推导的误比特率公式的正确性.结果表明,当信道估计误差与信道增益之比(EGR)不断增大时,误比特率逐渐出现平台现象.当EGR小于-15 dB时,非理想信道估计带来的误比特率增加非常缓慢.而当分集支路之间的衰落相关系数小于0.4时,衰落相关带来的误比特率增加量不是很严重.文中还讨论了Nakagami信道衰落参数m对系统性能的影响.

Performance Analysis of Space-Time Transmit Diversity with Imperfect Channel Estimation over Correlated Nakagami Fading Channels

In this paper, we investigate the impact of imperfect channel estimation and correlated Nakagami fading channels on the performance of STTD(space-time trnasmit diversity) carefully. Firstly, on the assumption of channel estimation error with Gaussian distribution, the signal to noise ratio at the receivers is analyzed. Previous work on performance analysis of STTD has been restricted to uncorrelated Rayleigh fading. In this paper, we derive a closed-form bit error probability (BER) expression for STTD with two transmit antennas and arbitrary number of receive antennas under correlated Nakagami fading channels with arbitrary correlation variance matrix. Finally, numerical results from simulations are given to support the mathematical development of the BER expression, and shown that there is a floor for BER at high SNR as the channel estimation error to channel gain ratio (EGR) increases. We found that the speed for BER performance degradation decreases fairly slowly when EGR<-15 dB, and the effect of the channel correlation is not significant for correlation coefficient around 0\^4. The effect of fading parameter m of Nakagami distribution on the performance of STTD is also discussed.