频率选择性衰落信道中多用户OFDM系统的自适应分配算法

An Adaptive Allocation Algorithm for Multiuser OFDM System over Frequency Selective Fading Channels

本文提出一种适用于多径频率选择性衰落信道中多用户OFDM系统的自适应分配算法 .算法根据信道瞬时估计值 ,自适应地为多用户分配子信道和传输比特数 ,在给定误比特率的条件下 ,使系统总的发送功率达到最小 .作者根据时分复用的基本思想 ,提出多用户最佳子信道和比特分配算法 ,导出系统最小发送功率的下限 ,并在此基础上 ,进一步提出次佳自适应分配算法 .数值模拟表明 :次佳算法所需的发送功率比下限值高约 1dB ;与等比特分配方案相比自适应分配算法可节省功率约 3- 4dB ;与静态信道分配方案相比 ,自适应分配算法可节省功率 6 - 8dB .

In this paper,an adaptive allocation algorithm for multiuser Orthogonal Frequency Division Multiplexing (OFDM) system over multipath frequency selective fading channels is proposed.According to the estimation of instantaneous channel characteristics,the adaptive allocation algorithm assigns the subchannels and bits for multiuser in the system to minimize the total transmission power for a given bit error rate (BER).Firstly,we apply the conception of time division multiplexing to the system to propose an optimum subchannel and bit rate allocation algorithm for multiuser,which results a low bound of the transmission power in the system.Then,a suboptimum adaptive allocation algorithm is proposed.The numerical simulation shows that the transmission power determined by the suboptimum adaptive allocation algorithm is 1dB bigger than that of the low bound;3-4dB less than that in equal bit allocation (EBA) and 6-8dB less than that in static subchannel allocation (SSA).