本文選題：高速鐵路　切入點(diǎn)：上行鏈路傳輸系統(tǒng)　出處：《蘭州交通大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：為了滿足高速數(shù)據(jù)傳輸業(yè)務(wù)以及需求,新一代長(zhǎng)期演進(jìn)的移動(dòng)通信系統(tǒng)(LTE)應(yīng)運(yùn)而生,其下行采用了正交頻分復(fù)用多址(OFDMA)的技術(shù),上行采用了單載波頻分復(fù)用(SC-FDMA)的技術(shù)。高速運(yùn)動(dòng)環(huán)境下多普勒頻移的增大會(huì)使得信道產(chǎn)生快速時(shí)變的衰落,并且破壞了子載波之間的正交性,使得系統(tǒng)尤其是上行鏈路的性能受到嚴(yán)重的影響。因此,對(duì)于高速移動(dòng)環(huán)境下上行鏈路傳輸系統(tǒng),本文從多普勒頻偏的估計(jì)技術(shù)和時(shí)變信道的估計(jì)技術(shù)兩個(gè)方面來進(jìn)行了較為深入的研究,下面即為本文主要的研究工作內(nèi)容:首先進(jìn)行了上行鏈路信道的研究,分析研究了高速移動(dòng)傳輸信道以及影響上行鏈路傳輸系統(tǒng)性能的主要因素,給出了國內(nèi)外的高鐵信道模型,進(jìn)行了國內(nèi)的高鐵在不同場(chǎng)景下信道傳輸模型的研究,并且得到了上行鏈路傳輸系統(tǒng)的時(shí)變信道模型。此外,從相同信道場(chǎng)景和不同信道場(chǎng)景兩個(gè)方面,分析了影響TD-LTE上行鏈路系統(tǒng)性能的幾個(gè)主要因素。其次進(jìn)行了上行鏈路中多普勒頻偏估計(jì)技術(shù)的研究,研究了現(xiàn)有的傳統(tǒng)頻偏估計(jì)的算法,提出了改進(jìn)的頻偏估計(jì)算法。在高速場(chǎng)景下,改進(jìn)方法采用粗估計(jì)與精估計(jì)結(jié)合的方法,利用自回歸模型在子幀之間對(duì)于頻偏估計(jì)值進(jìn)行跟蹤處理,因此提高了估計(jì)的精度,降低了噪聲的干擾以及計(jì)算復(fù)雜度。給出了改進(jìn)算法與現(xiàn)有算法系統(tǒng)性能仿真比較,結(jié)果表明改進(jìn)算法具有更好的性能增益。最后進(jìn)行了上行鏈路中時(shí)變信道估計(jì)技術(shù)的研究,分析了現(xiàn)有的信道估計(jì)算法,根據(jù)現(xiàn)有信道估計(jì)算法的不足之處提出了改進(jìn)算法,即先在重新定義的變換域中處理,在一子幀的長(zhǎng)度上利用多項(xiàng)式擬合的方法得到信道上所有符號(hào)上的參數(shù)估計(jì)值,在子幀間采用帶有變化跟蹤因子的AR模型進(jìn)行跟蹤處理,因此提高了信道上導(dǎo)頻符號(hào)兩端數(shù)據(jù)符號(hào)參數(shù)估計(jì)值的精度,再根據(jù)信道之間的轉(zhuǎn)換關(guān)系,將其從變換域轉(zhuǎn)換到頻域中。所得到的信道估計(jì)響應(yīng)是可以進(jìn)行頻域均衡的。仿真分析比較了改進(jìn)算法與現(xiàn)有算法系統(tǒng)的性能優(yōu)劣,改進(jìn)算法降低了系統(tǒng)計(jì)算復(fù)雜度,因此更具優(yōu)勢(shì)。
[Abstract]:In order to meet the needs of high-speed data transmission, a new generation of long-evolving mobile communication system (LTEs) emerges as the times require, and its downlink adopts OFDMA (orthogonal Frequency Division Multiplexing) technology. The uplink uses SC-FDMA (single Carrier Frequency Division Multiplexing) technique. The increase of Doppler frequency shift in high-speed moving environment will cause fast time-varying fading of the channel and destroy the orthogonality between subcarriers. The performance of the system, especially the uplink, is seriously affected. Therefore, for the uplink transmission system in high-speed mobile environment, In this paper, the Doppler frequency offset estimation technique and time-varying channel estimation technology are studied in depth. The following is the main work of this paper: firstly, the uplink channel is studied. The high speed mobile transmission channel and the main factors affecting the performance of uplink transmission system are analyzed, and the domestic and foreign high-speed rail channel models are given, and the channel transmission models of the domestic high-speed rail transmission system under different scenarios are studied. Moreover, the time-varying channel model of uplink transmission system is obtained. Several main factors affecting the performance of TD-LTE uplink system are analyzed. Secondly, the Doppler frequency offset estimation technology in uplink is studied, and the existing traditional frequency offset estimation algorithms are studied. An improved frequency offset estimation algorithm is proposed in this paper. In high speed scene, the improved method combines coarse estimation with refined estimation, and uses autoregressive model to track the frequency offset between subframes, so the estimation accuracy is improved. The simulation results show that the improved algorithm has better performance gain. Finally, the time-varying channel estimation technique in uplink is studied. In this paper, the existing channel estimation algorithms are analyzed, and an improved channel estimation algorithm is proposed according to the shortcomings of the existing channel estimation algorithms, that is, it is first processed in the redefined transform domain. The parameter estimation of all symbols on the channel is obtained by polynomial fitting on the length of a subframe, and the AR model with variable tracking factor is used to track the parameters between subframes. Therefore, the accuracy of the estimation of the data symbol parameters at both ends of the pilot symbols on the channel is improved, and then according to the conversion relationship between the channels, The channel estimation response can be equalized in frequency domain. The performance of the improved algorithm is compared with that of the existing algorithm. The improved algorithm reduces the computational complexity of the system. So it has an advantage.
【學(xué)位授予單位】：蘭州交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TN929.5

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