基于延迟CSIT的非对称双向中继X信道传输方案

Transmission Scheme for Asymmetric Two-way Relay X Channel Based on Delayed CSIT

在快速衰落信道中,当发送端不具备即时的信道状态信息(CSIT)时,利用延迟信道状态信息能够提高系统的自由度。假设系统每个节点具有延迟CSIT,研究了非对称(即中继两侧用户数不相等)双向中继X信道的自由度。将传输过程分为MAC和BC两个阶段,提出了一种结合干扰对齐与物理层网络编码的多级传输方案,利用延迟CSIT在多个时隙解码期望消息。实验结果表明,本方案可以实现比Vaze提出的上界高21.8%的复用增益,同时,相对于TDMA方案提升了166.7%。分析结果表明,相对于TDMA方案和Vaze界,该方案能够实现一定程度的自由度增益。

In the fast fading channel,when instantaneous channel state information at transmitter(CSIT)is unavailable,the delayed channel state information can be used to improve the degree of freedom(DoF)of the system.Assuming that each node of the system has a delayed CSIT,the DoF of asymmetrical(with unequal number of users on the both sides of the relay)bidirectional relayed X-channels was investigated in this paper.The transmission procedure was divided into two phases,including multiple access channel(MAC)and broadcast channel(BC).A multi-stage transmission scheme combining interference alignment and physical layer network coding was proposed,which uses the delayed CSIT to decode the desired messages in multiple time slots.The experimental result shows that the proposed scheme can achieve a multiplexing gain of 21.8%,which is higher than the upper bound proposed by Vaze,and get an increase of 166.7%compared with the TDMA scheme.The analysis result shows that the proposed scheme can achieve some DoF gain compared with the TDMA scheme and Vaze bound.