Research On Reducing Peak-to-average Power Ratio Of Orthogonal Frequency Division Multiplexing System In Power Line Communication

Orthogonal frequency division multiplexing(OFDM)has fast data transmissionrate,high spectrum efficiency and effective robustness to frequency selective fading, andhas become the modulation method of the power line communication system.But, becausethe OFDM signal is many sub-carriers’ superposition, there is a high peak-to-averagepower ratio(PAPR), limits it’s application. Therefore, the PAPR reduction has become oneof the key technologies of OFDM system.This article analysize the power line channelmodel and the channel characteristics in detail, it mainly studies on the methods ofreducing the PAPR of OFDM system in power line communication.Firstly, in view of the transform matrix selective mapping algorithm has a defect thatthe number of candidate signals is limited,this article improves it.The improved methodseparates the signal’s real and imaginary component, then transformed them throughtime-domain sub-block conversion matrices,which can produce more candidate signals,and further reduce the PAPR of the system.Secondly, in view of the problem of traditional tone injection(TI) algorithmcomputational complexity is very high in searching the optimal solution, this paperproposes a tone injection algorithm based on particle swarm optimization (PSO-TI).Thisalgorithm transforms the traditional tone injection algorithm to the problem of solving theglobal optimization.It reduces complexity of the algorithm greatly by introducing theparticle swarm optimization to find the optimal solution.Finally, in view of the problem of traditional constellation extension(CE) algorithmcomputational complexity is very high in searching all the permutation and combinationof the constellation extension mapping,this paper proposes a constellation extensionalgorithm based on quantum-inspired evolutionary(QEA-CE). This algorithm solves theglobal optimization of the traditional constellation extension algorithm by usingquantum-inspired evolutionary, it’s complexity is reduced obviously.The above three methods’ complexity are all be analyzed, their PAPR reduction andBER performance under the power line channel are all verified by the simulation in thisarticle.