OFDM系统中一种改进的低复杂度自适应比特功率分配算法

针对正交频分复用(orthogonal frequency division multiplexing,OFDM)系统在进行自适应比特功率分配时存在过高复杂度的问题,提出了一种基于边缘自适应(margin adaptive,MA)准则的改进低复杂度自适应比特功率分配算法.与贪婪(Greedy)算法相比,提出的改进算法通过预分配和迭代分配2部分来降低算法的计算量.改进算法先在预分配中根据信道条件预先分配部分比特,在迭代分配中通过增大内存开销的方法减少Greedy算法中计算和比较每个子信道功率增量的次数,从而降低算法的复杂度.仿真结果表明,在相同的仿真环境下算法的自适应分配效果和Greedy算法的自适应分配效果基本一致,同时该算法和Greedy算法具有几乎相同的误比特性能.且随着子信道数量的增加,与Greedy算法相比,该算法的运行时间更短,进而说明所提出的算法具有较低的复杂度.

An improved adaptive bit power allocation algorithm with the low complexity for OFDM system

According to the high complexity defect of orthogonal frequency division multiplexing(OFDM) systems in the adaptive bit power allocation, an improved low complexity adaptive bit power allocation algorithm based on margin adaptive (MA) criterion was proposed. Compared with the Greedy algorithm, the proposed improved algorithm can reduce the calculation amount by means of the pre-allocation and the iterative allocation. The improved algorithm will firstly allocate partial bits according to the channel condition in the pre-allocation and then the times of calculating and comparing the power increment for each subchannel in the Greedy algorithm can be reduced by means of increasing the memory overhead in the iterative allocation, thus the complexity of the algorithm is reduced. Simulation results show that in the same simulation environment, the adaptive allocation results of the proposed algorithm and the Greedy algorithm are almost the same, and the proposed algorithm and the Greedy algorithm have almost the same bit-error performance. However, with the increase of the number of subchannels, compared with the Greedy algorithm, the running time of the proposed algorithm is shorter, and then it shows that the proposed algorithm has a low complexity.