协同OFDM放大前传空时编码系统中的功率分配

摘要

针对由源节点和单个中继节点形成的协同正交频分复用( OFDM) Alamouti空时块码系统,分析了放大前传(AF)模式下的系统容量,给出了解析表达式.考虑节点功率独立约束的应用场景,提出了分步迭代的功率分配算法( SIPAA)来提高系统容量.该算法的核心思想是在每次迭代中,分步对源和中继节点分别进行注水功率分配,注水功率分配前对目标函数进行线性化处理,功率分配后对功率分配向量进行线性化处理以降低算法复杂度.仿真结果表明,相对于等功率分配算法,所提出的分步迭代功率分配算法可以显著提高系统容量,且仅需很少几次迭代运算就可以完成功率分配.%A cooperative orthogonal frequency division multiplexing (OFDM) system with a source and a non-regenerative relay transmitting according to Alamouti' s STBC is considered. The capacity of the system is analyzed and the analytical expression is presented. To improve the capacity of the individual power constrained system, a power allocation algorithm named as the Stepwise Iterative Power Allocation Algorithm (SIPAA) is proposed. The basic principle of SIPAA is that the water-filling power allocation is implemented stepwise for both the source and the relay within iterations. To reduce the complexity of SIPAA, the object function is linearly processed before the water-filling power allocation, and the power vector is also linearly processed after the water-filling power allocation. It is confirmed by the simulation results that a significant system capacity improvement can be achieved by the proposed algorithm, compared with conventional equal power allocation algorithm. Moreover, the power allocation can be completed within a few iterations.