物理層網(wǎng)絡(luò)編碼的符號時鐘估計
doi: 10.11999/JEIT141364
基金項目:
國家自然科學(xué)基金(61172078, 61201208)，教育部留學(xué)回國人員科研啟動基金和中央高?；究蒲袠I(yè)務(wù)費(NS2014038)
Symbol Timing Estimation for Physical-layer Network Coding
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摘要: 現(xiàn)有的關(guān)于物理層網(wǎng)絡(luò)編碼(PNC)的研究多建立在時鐘已完全同步的基礎(chǔ)上，對PNC的符號時鐘同步研究較少。而實際上符號時鐘在PNC中是必不可少的。針對這一問題，該文提出一種新的基于正交訓(xùn)練序列適用于雙向中繼信道PNC的符號時鐘估計方法。該方法根據(jù)最大似然估計準(zhǔn)則，運用基于離散傅里葉變換(DFT)的插值算法來估計時鐘誤差。仿真結(jié)果表明，所提出的DFT插值算法性能優(yōu)越，在信噪比(SNR)大于10 dB的條件下，系統(tǒng)的均方誤差(MSE)性能比經(jīng)典優(yōu)選采樣點法提升1個數(shù)量級，并且非常逼近修正克拉美羅界(MCRB)。
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關(guān)鍵詞:
- 無線通信 /
- 物理層網(wǎng)絡(luò)編碼 /
- 雙向中繼信道 /
- 符號時鐘估計 /
- 修正克拉美羅界
Abstract: 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). -
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