针对DTMB-A系统的相位噪声消除算法  

Phase Noise Correction for DTMB-A System

作　　者：梁林峰[1] 王军[1] 宋健[1,2] 

机构地区：[1]清华大学电子工程系、清华信息科学与技术国家实验室,北京100084 [2]深圳市数字电视系统重点实验室,深圳518000

出　　处：《信号处理》2014年第7期749-756,共8页Journal of Signal Processing

基　　金：深圳市战略新兴产业发展专项资金(JCYJ20130401173351839);中国电力科学研究院项目支助(TX71-13-007)

摘　　要：相位噪声会破坏OFDM(Orthogonal Frequency Division Multiplex)符号内频域子载波的正交性,产生公共相位误差(CPE,Common Phase Error)和子载波间干扰(ICI,Inter-Carrier Interference),对系统性能造成严重影响。针对数字电视地面广播传输标准演进方案(DTMB-A)的相位噪声问题,本文提出了一种两步结合的相位噪声估计和消除算法。首先,利用相邻两帧的帧头符号中所包含的PN(Pseudo Noise)序列,对帧体符号内的公共相位误差进行粗估计;随后,对帧体数据子载波进行标记,选取合适的子载波集合用于估计公共相位误差和子载波间干扰的精确结果。由此获得相位噪声频域估计结果后,通过快速傅立叶变换(FFT,Fast Fourier Transform)得到时域估计结果并进行消除。和现有基于判决反馈的相位噪声估计算法对比,本文所提算法的创新性在于采用了粗估计和精确估计结合的方法,同时利用子载波标记的方法有效降低了由于错误判决导致的误码扩散。仿真结果表明在现有算法已经不能正常工作的情况下,本文所提算法还可以有效的抑制相位噪声对系统性能的影响。Phase noise destroys the orthogonality among subcarriers within one OFDM （Orthogonal Frequency Division Multiplex） block and causes common phase error （CPE） and inter-carrier interference （ICI）, which significantly degrades the performance of OFDM system. To deal with the problem of phase noise in DTMB-A system, a two-step phase noise estimation method is proposed in this paper. Firstly, the rough estimation of CPE in frame body symbol is obtained by PN （Pseudo Noise） sequence in the frame header symbol; Secondly, the accurate estimation of CPE and ICI is obtained by marking the data subcarriers in frame body symbol and choosing the suitable subearriers subset for decision feedback. The time domain estimation of phase noise is obtained by applying Fast Fourier Transform to the frequency domain estimation of phase noise, and then phase noise is corrected in time domain. Compared with the existing phase noise correction method, the innovation of proposed method is the combination of two-step estimations and the mitigation of error propagation problem cause by incorrect decision. Simulation results show that the proposed method can correct the phase noise effectively, even when the existing method fails.

关 键 词：数字电视地面广播 相位噪声 判决反馈 公共相位误差 子载波间干扰 

分 类 号：TN911.4[电子电信—通信与信息系统]