CAJ | 학술논문

现有的关于物理层网络编码(PNC)的研究多建立在时钟已完全同步的基础上，对PNC的符号时钟同步研究较少。而实际上符号时钟在PNC中是必不可少的。针对这一问题，该文提出一种新的基于正交训练序列适用于双向中继信道PNC的符号时钟估计方法。该方法根据最大似然估计准则，运用基于离散傅里叶变换(DFT)的插值算法来估计时钟误差。仿真结果表明，所提出的DFT插值算法性能优越，在信噪比(SNR)大于10 dB的条件下，系统的均方误差(MSE)性能比经典优选采样点法提升1个数量级，并且非常逼近修正克拉美罗界(MCRB)。
현유적관우물리층망락편마(PNC)적연구다건립재시종이완전동보적기출상，대PNC적부호시종동보연구교소。이실제상부호시종재PNC중시필불가소적。침대저일문제，해문제출일충신적기우정교훈련서렬괄용우쌍향중계신도PNC적부호시종고계방법。해방법근거최대사연고계준칙，운용기우리산부리협변환(DFT)적삽치산법래고계시종오차。방진결과표명，소제출적DFT삽치산법성능우월，재신조비(SNR)대우10 dB적조건하，계통적균방오차(MSE)성능비경전우선채양점법제승1개수량급，병차비상핍근수정극랍미라계(MCRB)。
Most of the existing research on Physical-layer Network Coding (PNC) is based on the assumption that the symbol timing at the relay is ideally synchronized, and rarely discusses the issue of symbol synchronization. However, in practice, the symbol timing is indispensable in PNC systems. To tackle this problem, this paper proposes a novel symbol timing estimation scheme based on the orthogonal training sequences for PNC in two-way relay channels. According to the maximum-likelihood estimation criterion, a Discrete Fourier Transformation (DFT) based interpolation algorithm is applied to improve the estimation accuracy. It is shown by analysis and simulation that the proposed DFT-based symbol timing estimator exhibits superior performance. The Mean Square Error (MSE) performance of the estimator is one order of magnitude better than that of the conventional optimum sample algorithm for Signal-to-Noise Ratio (SNR) greater than 10 dB, and is very close to the Modified Cramer-Rao Bound (MCRB).