关键词: 对数似然比, 发射天线选择, 衰落信道, 多输入多输出系统, 天线分集

Abstract: The antenna diversity based on Log-Likelihood Ratio (LLR) is a new technique which is better than that based on Signal-to-Noise Ratio (SNR) in code-error rate performance, and it provides a significant reduction in complexity and cost. In this paper, the new technique of transmit antenna selection based on LLR was studied and the expressions of transmit antenna selection schemes based on Symbol-LLR (SLLR) and Bit-LLR (BLLR) over Multi-Input Multi-Output (MIMO) Nakagami channel were derived. At the same time, the average Bit-Error Rate (BER) performance of M-ary modulated system was studied. The simulation results show that the BLLR scheme is optimum since it minimizes the BER of MIMO system. With the same total number of antennas, the system which possesses the higher diversity order exhibits better performance. Moreover, with the same diversity order, the BER performance is more preferable due to the higher number of receive antennas.

Key words: Log-Likelihood Ratio (LLR), transmit antenna selection, fading channel, Multiple-Input Multiple-Output (MIMO) system, antenna diversity