| With the rapid development of global mobile communication technology,people have higher and higher requirements on transmission speed and transmission quality.The previous communication system has been unable to meet the growing needs of people,and a new communication technology,the 5th Generation Mobile Networks(5G),has gradually stepped into the right track.At present,5G has entered every aspect of social life.However,the working frequency band of 5G system is mainly distributed in the high frequency band,and the high frequency will cause strong local oscillator self-excitation,which means that the signal will be affected by serious phase noise.At the receiving end,there are two main Interference caused by Phase noise:Common Phase Error(CPE)and inter-carrier Interference(ICI).How to better solve the signal interference caused by phase noise has become a subject worth studying.Based on the Phase Tracking Reference Signal(PTRS)introduced in 5G New Radio(NR),the Phase noise compensation algorithm of Cyclic Prefix-Orthogonal Frequency Division Multiplexing(CP-OFDM)system receiver is studied in this paper.Firstly,based on the distribution characteristics of PTRS in the frequency domain,the frequency domain density of PTRS is considered in the classical phase noise compensation algorithm,and the phase compensation module and channel estimation module are improved.The second point is based on the iterative method of mathematical method,and the iteration module is added into the existing phase noise compensation process,and the different performance of the improved algorithm and the traditional algorithm is analyzed by simulation.The main research contents of this paper are as follows:(1)Study on phase noise and OFDM technology.Based on the basic principle of OFDM and the basic model of phase noise,a CP-OFDM system model under the influence of phase noise is established.The influence of phase noise on transmitted signals in the system is further analyzed through theoretical derivation and simulation experiments.Finally,based on Demodulation Reference Signal(DMRS)and PTRS,which are two Reference signals involved in phase noise compensation in 5G NR,the phase error estimation method is deduced,which lays a foundation for subsequent phase noise compensation algorithms.(2)Based on the frequency distribution characteristics of PTRS,the phase noise compensation scheme in CP-OFDM system is optimized.Firstly,the classical phase noise compensation algorithm is studied,and the theoretical derivation and simulation are carried out.Then,the frequency domain density of PTRS is introduced into the compensation algorithm,and an improved phase noise compensation algorithm is proposed.(3)Based on the frequency distribution characteristics of PTRS,the channel estimation method is optimized.Based on the classical channel Estimation method Minimum Mean Square Estimation(MMSE),an improved channel Estimation method is proposed by combining the particle size of the channel Estimation with the frequency domain density of PTRS.(4)Phase noise compensation method based on iterative method.Based on the phase noise compensation process at the receiver of CP-OFDM system,an iterative model of the received signal and phase error estimation was established to gradually reduce the interference of the phase error estimation by the phase noise of the reference channel itself,and a new iterative algorithm for phase noise compensation was proposed.Finally,the proposed scheme is simulated on the simulation platform and compared with the traditional scheme.The experimental results show that the improved algorithms can reduce the influence of phase noise in different degrees and improve the system performance under various simulation conditions. |
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