MIMO频率选择性信道自适应均衡

针对MIMO频率选择性信道提出了一种分数间隔的判决反馈均衡器，其优点是既对时间同步误差不敏感，又能在消除码间干扰的同时不引入噪声增益。同时比较了分别采用最小均方算法和恒模算法的分数间隔判决反馈均衡器，并通过仿真，分析了这两种算法的优缺点。在此基础上提出了一种改进的最小均方算法和恒模算法相结合的算法，改进后需要的训练序列为LMS算法的1/3，其结果是误码率比恒模算法有明显的提高。
关 键 词 MIMO频率选择性信道; 分数间隔均衡; 判决反馈均衡; 最小均方算法; 恒模算法

Abstract This article researches the combination of fractionally spaced equalizer (FSE) and decision feedback equalizer(DFE) applied in MIMO frequency selective channels. This kind of equalizer has low sensitivity to the receiver’s sampling phase, and it can eliminate the ISI without adding noise gain. This paper analyses and compares the FSE-DFE applying two adaptive algorithms: least mean squares (LMS) algorithm and constant modulus algorithm (CMA). Through the simulation results, their respective advantages and disadvantages are presented. Based on these algorithms, a new hybrid algorithm possessing the advantages of LMS and CMA is proposed. This algorithm requires only a few training sequences and performs better than CMA.
Key words MIMO frequency selective channels; fractionally spaced equalizer; decision feedback equalizer; least mean squares algorithm; constant modulus algorithm