Power Allocation Algorithm for V-BLAST System with Channel Feedback Delay
YU Xiao-da · Jisuanji gongcheng · 2014
An Adaptive Transmission Power Allocation(ATPA) algorithm is presented for Vertical-bell Laboratories Layered Space Time(V-BLAST) system with feedback delay.The aim of proposing this algorithm is to minimize the overall Bit Error Rate(BER).At the receiver,Zero Forcing(ZF) detection technology is proposed and assuming that full channel state information can be obtained.The transmitter gets the information through a time delay feedback link.The algorithm computes the conditional Probability Density Function(PDF) of the real Signal Noise Ratio(SNR) according to the PDF of the SNR estimation,and the overall BER expression is worked out.At the transmitter,the transmit power of each antennas is obtained by solving the optimization problem under the total power constraint.Simulation results show that the proposed ATPA algorithm can effectively improve the BER performance.It is proved that if the performance requirement of BER=10~(-3),the normalized feedback delay factor is equal to 0.000 1,the modified V-BLAST system with adaptive transmit power allocation outperforms the conventional V-BLAST system about 5 dB when the feedback links with a delay.