物理层网络编码中连续相位调制信号的非相干多符号检测

摘要

Physical-layer Network Coding (PNC) with Continuous Phase Modulation (CPM) attractes much attention due to its high efficiency in the throughput and the spectrum. Most present research on the detection of CPM-PNC signals is based on the assumption that signals transmitted from the two nodes arrivd at the relay haue perfect carrier synchronization or the carrier-phase offset is known. In practical applications, however, the carrier-phase offset is unavoidable and hard to estimate accurately. In this paper, a noncoherent multiple symbol detection algorithm for CPM-PNC signals is proposed to solve this problem. The proposed algorithm, which is based on the maximum likelihood principle, fully exploits the inherit memory of CPM signal and makes decision on the middle symbol by observing a group of symbols. Simulation results show that the performance of the proposed CPM-PNC noncoherent multiple symbol detection algorithm is superior. In addition, as the observation length gets larger, the performance of the proposed algorithm increases significantly and approaches that of CPM-PNC optimal coherent detection. When BER is410, compared with observation length of 1 symbol, the algorithm with observation length of 5 symbols achieves 6.7 dB performance gain.%基于连续相位调制(CPM)的物理层网络编码(PNC)由于其高效的吞吐率和频谱利用率特性引起了越来越多的关注。现有关于 CPM-PNC 检测的研究大多建立在到达中继端的两节点信号载波相位完全同步或相位差已知的基础上。实际应用中，这一载波相位差不可避免，也很难准确估计。针对这一问题，该文提出一种中继端存在未知载波相位差条件下的 CPM-PNC 非相干多符号检测算法。该算法根据最大似然检测原理，通过观察多个码元来实现中间码元的检测，充分利用了CPM 信号的相位记忆特性。仿真结果表明，该文所提出的CPM-PNC非相干多符号检测算法性能优越。而且随着观察窗口长度的增大，其性能显著提高并逐渐趋近最优相干检测性能。在误码率(BER)为410时，相比于非相干单符号检测，观察窗口长度为5个码元时的CPM-PNC非相干多符号检测有6.7 dB的性能增益。