非对称双向中继信道中断概率分析与功率分配策略

Outage probability analysis and power allocation strategy for asymmetric two-way relay channel

摘要:

为改善非对称瑞利衰落信道下双向放大转发中继系统的中断性能，提出一种新的最小化中断概率的功率分配方案.引入非对称因子，通过理论分析给出传统三节点网络结构中4种非对称双向中继信道下系统中断概率的闭合表达式，并通过仿真比较发现下行信道非对称系统中断性能最差.针对下行信道非对称系统，利用基于信道状态信息的用户节点功率分配方案来最小化中断概率，该方案中功率分配值为与非对称因子有关的分段函数，节点能根据信道状态的变化自适应调整发射功率.仿真实验结果表明：提出的功率分配方案可以改善下行非对称双向中继系统的中断性能，与等功率分配方案相比，非对称因子越小，改善效果越好.

Abstract:

To improve the outage performance of a bidirectional amplify and forward relaying system in an asymmetric Rayleigh fading channel, a new power allocation scheme based on minimizing the outage probability is proposed. First, the asymmetry factor is introduced, and under the theoretical analysis, the closed outage probability expressions of four cases asymmetric two-way relay channel with traditional three nodes network structure is derived. Simulation results show that downlink asymmetry is the worst case. Furthermore, in order to minimize the downlink asymmetry system outage probability, a power allocation scheme based on channel state information is proposed. In this scheme, the power allocation is a piecewise function of the asymmetry factor. The node can adjust the transmission power adaptively according to the variation of the channel state. Simulation results show that the proposed power allocation scheme can improve the outage performance of the downlink asymmetric two-way relay system. Compared with the equal power allocation scheme, the smaller the asymmetry factor is, the better the effect is.