Abstract: The capacity of MIMO (multiple_input_multiple_output) systems with periodic feedback is investigated. Given the feedback capacity constraint in terms of maximum number of feedback bits per block, when the number of CSI(channel state information) quantization bits increases, the quantization error decreases with enhancing the capacity, while the feedback period increases with reducing the capacity. Hence, there exists an optimal number of CSI quantization bits to maxi mize the capacity. The opti mal number of CSI quantization bits is obtained by numerical calculations. Moreover, the numerical results show that the periodic feedback strategy is effective compared to the traditional feedback strategy.

Key words: multiple-input- multiple-output (MIMO), capacity, periodic feedback

摘要： 研究了基于周期反馈MIMO(multiple_input_multiple_output)系统的容量。在给定反馈容量约束(平均每一个块的时间内最多能反馈的比特数)的情况下, 当CSI(channel state information)的量化比特数越大时, 一方面,CSI的量化误差越小, 从而增大容量; 另一方面, 反馈周期越大, 导致降低容量。因此, 对于周期反馈系统的容量而言,存在最优的CSI量化比特数。通过数值计算, 给出了最优的CSI量化比特数。计算结果表明:与传统的反馈策略相比, 周期反馈策略使得系统容量得到较大提升。

关键词: 多输入多输出, 容量, 周期反馈