非理想载波同步物理层网络编码误比特性能分析  

BER Performance Analysis of Physical-Layer Network Coding with Imperfect Carrier Synchronization

作　　者：赵坤[1] 张邦宁[1] 潘克刚[1] 刘爱军[1] 郭道省[1] 

机构地区：[1]解放军理工大学通信工程学院,南京210007

出　　处：《信号处理》2014年第4期457-469,共13页Journal of Signal Processing

摘　　要：采用相干检测的物理层网络编码系统的误比特性能与载波同步精度密切相关,收发双方的载波同步误差将引起系统性能恶化。本文研究了残余载波同步误差对采用相同星座和正交星座BPSK信号的两种物理层网络编码双向中继系统误比特性能的影响。首先基于最大似然准则推导了存在残余载波同步误差时中继节点及源节点处接收信号的判决区域,然后运用Craig极坐标法分析了系统多址接入、广播阶段及总的端到端误比特性能,得出了精确的误比特率表达式,文中的分析方法可推广到采用其他调制方式的物理层网络编码系统。计算机仿真表明:文中的理论分析与仿真结果完全吻合,所推导的理论公式可有效地评估BPSK调制物理层网络编码系统的误比特性能;正交星座系统对载波同步误差更为敏感,相同的同步误差对正交星座系统的性能恶化更为严重。The bit error rate （BER） performance of a physical-layer network coded two-way relay （PNC-TWR） system which adopts coherent detection is closely related to the carrier synchronization,the residual carrier offset between the transmitter and receiver will result in severe performance degradation.In this paper,we investigate the effect of the carrier offsets on the BER performance of two PNC-TWR systems,where the two source nodes employ same or orthogonal binary phase shift keying （BPSK） constellations.We first determine the decision regions for the received signals at the relay and source nodes based on the maximum likelihood （ML） nle,then by applying Craig＇s polar coordinate analyzing method,exact expressions of multiple access channel （MAC）,broadcast channel （BC） and sum end-to-end （E2E）BER are derived.The proposed analyzing approach can be generalized to other systems.Computer simulations demonstrate that our theoretical analysis accurately matches with the simulation results and the derived theoretical expressions can effectively evaluate the BER performance of the BPSK modulated PNC-TWR systems.It is also shown that the orthogonal constellation scheme is more sensitive to the cartier offsets than the same constellation scheme,and same carrier offsets result in larger performance loss to the orthogonal constellation scheme.

关 键 词：双向中继 物理层网络编码 残余载波同步误差 误比特率 端到端误比特率 

分 类 号：TN925[电子电信—通信与信息系统]