有限反馈和信道时延下的协作多点传输

Coordinated multi-point transmission with limited feedback and channel delay

针对实际系统中存在信道延迟和有限反馈,即非完全信道状态信息(CSI),在研究基于多点协作基站簇系统的基础上,得出了在非CSI情况下的每基站容量表达式和由此所造成的容量损失的上界.另外,针对一个给定了可接受的容量损失的系统,得出了终端需要反馈的最小比特数.由于此结论的得出是基于误差值的上界,所以与实际值存在一定的误差.仿真结果表明,容量损失会随着信道时延的减少和反馈比特数的增加而减小.同时,当信道时延到达一定的值时,如果通过增加反馈比特数来减少系统容量损失,起到的效果是非常有限的.另外,随着信噪比的逐渐增大,在非完全信道状况下的容量增长幅度要远小于完全信道状况下的容量增长幅度.

Based on clustered base station （BS） coordination and the channel delay and limited feedback in practical systems, the expressions for the data rate and rate loss upper bound per cell are derived with imperfect channel state information （CSI）. Thus, given the affordable rate loss, the minimum number of feedback bits can be calculated using the upper bound. Duo to the fact that this value is derived from the upper bound, it is not very accurate. Numerical results show that the rate loss reduces when the number of feedback bits increases and the channel delay decreases. On the other hand, when the channel delay increases gradually, the rate loss can be improved little by the increase of feedback bits. Meanwhile, as SNR increases, the system performance with the imperfect CSI improves more slowly than that with the perfect CSI.