Research On Methods Of Phase Noise Suppression In High-Order Modulation System

Digital microwave communication is a wireless communication which is suitablefor variety of capacity, distance and environment. With the continued integration anddevelopment of communication services, the demand of information transmission rateof digital microwave communication system keep increasing. The contradictionbetween the increasing information transmission rate and the limited system bandwidthis very outstanding. High-order modulation is an effective means to resolve thiscontradiction, but this means is very sensitive to phase noise. The main work of thispaper is to research the suppression algorithms of phase noise in high-order modulationsystem.Firstly, various models of phase noise in communication system and the influenceof phase noise on system are analyzed. Simulation methods of phase noise generationare briefly discussed. Secondly, in order to compensate phase noise, according to theanalysis of signal model and stochastic property of phase noise, a newdecision-directed (DD) interpolation algorithm in pilot-aided system is proposed.Simulation results show that in AWGN channel, the proposed algorithm has a muchbetter performance compared with the existing estimation and compensationalgorithms. And then, Based on the presented estimation and compensation algorithm,a new anti-phase noise carrier recovery loop is proposed. Simulation results show thatthe new carrier recovery loop achieve a better anti-phase noise performance comparedwith the existing anti-phase noise carrier recovery loop.Finally, combined with practical system, this paper analyzes the statisticaldistribution characteristics of the input signal of the de-mapping module in detail. Hardand soft decision algorithms taking phase noise into account in de-mapping module areresearched, and the performance simulation is performed for these algorithms oncomputer simulation platform.