存在信道反馈延迟时Turbo-BLAST系统的自适应功率分配算法

摘要

The suboptimal and optimal adaptive transmit power allocation algorithms are proposed to minimize the Bit Error Rate (BER) performance for Turbo-BLAST system with channel feedback delay. The conditional probability density function of the instantaneous Signal Noise Ratio (SNR) is deduced by system modeling and performance analysis. The system BER can be computed using mathematical transformation. At the transmitter, with the total transmit power constraint condition, the suboptimal and optimal transmit power matrix can be calculated by using the Lagrange multiplier method and Newton iteration technique, respectively. At the receiver, the iterative soft interference cancellation algorithm based on Zero Forcing (ZF) rule is used to detect the received symbols. Simulation results show that the proposed algorithms can improve the system BER performance. The optimal power allocation algorithm can improve BER performance more at the cost of increasing the computational complexity. The system performance can be further improved by iterative detection.%该文针对信道反馈有延迟的Turbo-BLAST系统，以误比特率(Bit Error Rate, BER)为优化目标，提出次优和最优两种自适应功率分配算法。通过系统建模和性能分析，推导出系统瞬时信噪比(Signal Noise Ratio, SNR)的条件概率密度函数，利用数学变换得到信道反馈有延迟时系统BER的表达式。发送端在总功率约束条件下，分别采用拉格朗日极值法和牛顿迭代法求解功率分配矩阵的次优解与最优解。接收端采用基于迫零(Zero Forcing, ZF)准则的软干扰抵消算法进行迭代检测。仿真结果表明，和等功率分配相比，采用该文所提两种算法均可改善系统的BER性能。最优功率分配算法以增加计算复杂度为代价更好地改善了系统的BER性能，而接收端的迭代检测可进一步改善系统性能。