一种基于分布式空时码的协作MIMO分集复用折衷新方案

摘要

Cooperative MIMO which is composed of multiple single antenna nodes by cooperative communication could construct multipte virtual transmit antennas. Spatial diversity gain could be obtained from this virtual MIMO multiple antenna arrays. Considered the specific features of cooperative MIMO, code cooperation strategy with distributed space-time coding is implemented in the network. An enhanced divemity-multiplexing tradeoff (DMT) scheme based on distributed space-time ceding (DSTC) in cooperative MIMO is studied. The expression of outage probability and diversity gain of two DSTC strategies are derived in detail. Based on the two DMT schemes of DSTC, the optimal DMT and outage performance of the enhanced DMT strategy could be obtained through altering the threshold of multiplexing gain adaptively. Numerical results indicate that, the proposed DMT scheme could be asymptotical to DMT upper bound in cooperative MIMO, and the corresponding outage performance is also inferior to that of upper bound. Hence, cooperative diversity gain and optimum outage behavior could be achieved simultaneously by the proposed DMT scheme for DSTC code cooperation in multi-node cooperative MIMO scenario.%协作MIMO通过多个单天线节点的相互协作构造多发射天线,以此形成一种虚拟MIMO多天线阵列获得空间分集增益.考虑到协作MIMO特点,天线间采用分布式空时编码进行编码协作.文章研究了协作MIMO中基于分布式空时码(DSTC)的分集复用折衷(DMT)新方案,该方案通过推导两种DSTC的中断概率与分集增益表达式,结合两类DSYC的DMT策略,根据改变复用增益阈值自适应获得最佳DMT与中断性能.数值仿真表明,所提的DMT策略可以逼近协作MIMO的DMT上限,协作节点采用该策略的中断性能仅次于上限的中断性能.在多节点构成协作MIMO网络分布式空时编码协作中,提出的DMT新方案可使系统高效地获得协作分集增益与中断性能.