【摘要】：物理層網(wǎng)絡(luò)編碼(PNC)作為一種新穎的中繼傳輸技術(shù),在頻譜效率和吞吐量方面具有巨大優(yōu)勢(shì)而備受人們關(guān)注。目前,關(guān)于PNC的研究大多假設(shè)兩個(gè)用戶節(jié)點(diǎn)發(fā)送的符號(hào)在中繼處完全對(duì)齊,即沒(méi)有符號(hào)同步誤差。然而,實(shí)際情況往往并不滿足這一條件,造成系統(tǒng)性能下降。因此,PNC的符號(hào)時(shí)鐘估計(jì)至關(guān)重要。本文研究雙向中繼信道PNC的符號(hào)時(shí)鐘估計(jì)問(wèn)題,基于CAZAC訓(xùn)練序列先后提出三種全新的適用于不同采樣率下的時(shí)鐘估計(jì)算法,分別是:過(guò)采樣率(每個(gè)碼元的采樣點(diǎn)數(shù))Q≥4的基于DFT插值的時(shí)鐘估計(jì)算法、過(guò)采樣率Q=2的低過(guò)采樣率時(shí)鐘估計(jì)算法,和波特率采樣的時(shí)鐘估計(jì)算法。論文首先根據(jù)PNC信號(hào)模型以及最大似然估計(jì)準(zhǔn)則,利用訓(xùn)練序列的零自相關(guān)特性,得到兩個(gè)端節(jié)點(diǎn)各自的時(shí)鐘誤差估計(jì)似然函數(shù),進(jìn)而提出運(yùn)用基于DFT的插值算法來(lái)估計(jì)時(shí)鐘誤差。然后針對(duì)上述算法采樣率過(guò)高的問(wèn)題,提出一種Q=2下的低過(guò)采樣率時(shí)鐘估計(jì)算法。該算法根據(jù)似然函數(shù)的兩個(gè)離散值之差與時(shí)鐘誤差是一一對(duì)應(yīng)的關(guān)系,利用已知的發(fā)送脈沖形狀和最小二乘法求一個(gè)擬合多項(xiàng)式來(lái)近似這種函數(shù)關(guān)系,從而實(shí)現(xiàn)時(shí)鐘誤差估計(jì)。最后為了進(jìn)一步降低采樣率,通過(guò)分析波特率采樣下的接收信號(hào),定義一種指示時(shí)鐘誤差大小的定時(shí)函數(shù),并估計(jì)出該定時(shí)函數(shù),實(shí)現(xiàn)波特率采樣下的時(shí)鐘估計(jì)。三種算法均在MATLAB平臺(tái)上以均方誤差(MSE)為性能指標(biāo)進(jìn)行仿真,同時(shí)探討各種參數(shù)對(duì)算法性能的影響。仿真表明,三種算法都能取得較好的時(shí)鐘估計(jì)結(jié)果,在32位的訓(xùn)練序列長(zhǎng)度及18 d B的信噪比(SNR)條件下,MSE可達(dá)1×10~(-4)。
[Abstract]:As a novel relay transmission technology, physical layer network coding (PNC) has great advantages in spectrum efficiency and throughput. At present, most researches on PNC assume that the symbols sent by the two user nodes are completely aligned at the relay, that is, there is no symbol synchronization error. However, the actual situation often does not meet this condition, resulting in a deterioration of system performance. Therefore, the symbol clock estimation of PNC is very important. In this paper, the symbol clock estimation problem of bidirectional relay channel PNC is studied. Based on the CAZAC training sequence, three new clock estimation algorithms are proposed, which are suitable for different sampling rates. They are: the clock estimation algorithm based on DFT interpolation for oversampling rate (sampling points per symbol) Q 鈮，

本文編號(hào)：2289344