一种MA准则下改进的OFDM系统自适应比特功率分配算法

针对经典贪婪算法(greedy)迭代次数多、运算量大的缺点，提出一种基于边缘自适应(margin adaptive, MA)准则的改进贪婪算法来进行正交频分复用(orthogonal frequency division multiplexing, OFDM)系统的自适应比特功率分配。与贪婪算法相比，改进算法通过预分配和迭代分配两部分来降低算法的计算量。在预分配中改进算法通过引入功率利用率函数，对信道条件好的子信道预先加载一部分比特。然后，在迭代分配的过程中，引用分类排序的思想，用一张表格存储子信道的功率变化情况，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，改进算法和Greedy算法的误比特性能几乎一致，但改进算法的运行时间更短。

An improved adaptive bit power allocation algorithm for OFDM system based on MA criterion

According to the defects of the classical greedy algorithm such as the excessive iterations and the heavy computation, an improved greedy algorithm based on the margin adaptive (MA) criterion is proposed to adaptively allocate the bit power of orthogonal frequency division multiplexing (OFDM) systems. Compared with the greedy algorithm, the proposed algorithm can reduce the calculation amount by means of the pre-allocation and the iterative allocation. A new function of the power utilization rate is used in the improved algorithm to pre-allocate a portion of the bits to the sub-channel with the good condition in the pre-allocation. Then, in the process of the iterative allocation, the power variation of the sub-channels, based on the concept of classification and sort, can be stored in a form, thus the complexity of the improved greedy algorithm is reduced. Simulation results show that the improved algorithm and the greedy algorithm have almost the same bit error performance in the same simulation environment, but the running time of the improved algorithm is shorter. Thus it is concluded that the improved greedy algorithm can reduce the complexity of the algorithm while ensuring its performance.