一种改进的电力线通信OFDM自适应比特分配算法

针对低压电力线信道的频率选择性衰落等特点,在总功率和峰值功率限制下提出一种低复杂度的自适应比特分配算法.该算法首先对子载波进行分组以降低计算复杂度,组内子载波将采用相同的调制方式.然后采用注水算法解决连续比特输入问题,将其得到的位向量取整后作为贪婪算法的初始比特分配向量,证明了位向量的有效性.根据得到的初始向量在每个子载波上进行比特增加贪婪操作或比特移除贪婪操作.仿真结果表明从初始比特向量开始,每个子载波上最多只需进行一次比特增加或移除操作即可达到最佳吞吐量.与其他传统算法相比,在不同数量子载波、不同总功率约束等限制条件下,所提算法能在保证系统吞吐量的同时使其计算复杂度有效降低.

An improved bit allocation algorithm for PLC-OFDM system

To adapt to frequency selective fading of low-voltage power line, a new low-complexity adaptive bit loading algorithm is proposed under the total power and peak power constraints. Firstly, the subcarriers are grouped to reduce the computational complexity, the subcarriers in the group will use the same modulation scheme. And then the water-filling algorithm is used to solve the related continuous-input rate maximization problem, the rounding bit vector is used as the initial bit allocation vector of the greedy algorithm, this paper theoretically proves the validity of the bit vector. Finally, according to the initial vector, greedy-based bit-adding operations or greedy-based bit-removing operations are exploited on each subcarrier. The simulation results show that the optimized throughput, starting from the initial bit vector, is achieved by adding or removing bits on each subcarrier at most once. Compared with many algorithms in the literature, the proposed algorithm can guarantee the achievable throughput with significant reduction of computation cost under the different numbers of subcarriers and different total power constraints.