符号干扰多径信道下可达信道容量的预编码方案

摘要

提出了一种基于发射端已知信道状态信息(CSIT)的预编码方案,使发送和接收两端仅进行一次预编码和一次均衡运算就能获得多径满分集增益和逼近高斯理想信道的瞬时容量.首先,根据采用最小均方误差(MMSE)均衡的单载波频域均衡(SC-FDE)系统收发两端的互信息,给出一个收发互信息的理论上界.然后,发射端在已知CSIT条件下给出可达互信息理论上界的预编码方案,并且通过理论分析给出可达上界的预编码方案中断概率性能的闭合表达式.仿真结果表明:该方案能够有效改善系统的中断概率性能,在瑞利ISI信道下,能够将单纯采用MMSE均衡的SC-FDE系统的中断概率所需信噪比降低2~3 dB.同时,该方案所能达到的瞬时信道容量逼近于高斯信道下MMSE均衡系统的容量.%A novel precoding scheme is proposed with perfect Channel State Information at Transmitter (CSIT), which only takes one precoding and one Minimum Mean Square Error (MMSE) equalization at the transmitter and the receiver, respectively.Thus, the full diversity gain is obtained and the instant channel capacity approaches to the performance of Single-Carrier Frequency Domain Equalization (SC-FDE) in Gaussian channel.First, a theoretical mutual information bound between the transmitter and the receiver is presented based on the SC-FDE system with MMSE receiver.The, the precoding scheme is designed to achieve this bound.Through theoretical analysis, a closed-form expression on the outage probability of the system is derived.Simulation results demonstrate that the proposed scheme can reduce the outage probability of the traditional MMSE system by 2~3 dB and the instant channel capacity approaches to the performance of SC-FDE in Gaussian channel.