本文關(guān)鍵詞： 向量正交頻分復(fù)用 衛(wèi)星通信 全球衛(wèi)星導(dǎo)航系統(tǒng) 誤碼率 定位精度 稀疏信道 分集階數(shù)　出處：《南京大學(xué)》2017年博士論文　論文類型：學(xué)位論文

【摘要】：衛(wèi)星通信系統(tǒng)和衛(wèi)星導(dǎo)航系統(tǒng)發(fā)展到今天給人們的生產(chǎn)生活帶來(lái)了極大的便利,也同樣面臨著衛(wèi)星頻譜資源緊張、信道頻率選擇性衰落嚴(yán)重等許多亟待解決的問(wèn)題。現(xiàn)階段,盡管衛(wèi)星通信和衛(wèi)星導(dǎo)航面向不同的應(yīng)用領(lǐng)域,但從技術(shù)層面來(lái)看兩者之間存在密切聯(lián)系。一方面,衛(wèi)星通信的可靠性關(guān)系到接收機(jī)的抗干擾特性和導(dǎo)航電文的誤碼率,進(jìn)而影響接收機(jī)的定位精度。另一方面,導(dǎo)航定位信號(hào)通過(guò)對(duì)傳播時(shí)延的估計(jì)實(shí)現(xiàn)衛(wèi)星通信系統(tǒng)的碼元定時(shí)同步,而同步性能直接影響通信系統(tǒng)的可靠性。因此,在天地一體化信息網(wǎng)絡(luò)背景下,建設(shè)衛(wèi)星通信與導(dǎo)航一體化系統(tǒng)對(duì)于充分利用空間資源實(shí)現(xiàn)一星多用具有十分重要的意義。論文從通信和導(dǎo)航的基本性能指標(biāo)誤碼率和定位精度出發(fā),綜合考慮頻帶利用率、峰均功率比和系統(tǒng)復(fù)雜度等因素,提出了基于向量正交頻分復(fù)用(V-OFDM)調(diào)制的衛(wèi)星通信和導(dǎo)航一體化系統(tǒng),并對(duì)信道分配、導(dǎo)頻設(shè)計(jì)、信道估計(jì)、信號(hào)檢測(cè)、碼元同步等關(guān)鍵技術(shù)進(jìn)行了深入研究,取得了一系列創(chuàng)新性研究成果。首先,論文在比較單載波頻域均衡(SC-FDE)和正交頻分復(fù)用(OFDM)各自優(yōu)缺點(diǎn)的基礎(chǔ)上,綜合得出V-OFDM調(diào)制模型,并指出V-OFDM是連接SC-FDE和OFDM的橋梁。V-OFDM調(diào)制的思想是將一個(gè)碼間干擾信道劃分為多個(gè)向量子信道,其中向量維數(shù)可以靈活設(shè)計(jì)。然而,V-OFDM調(diào)制在個(gè)別子載波傳輸信號(hào)無(wú)法獲得分集增益,通過(guò)在發(fā)射端引入星座圖旋轉(zhuǎn)矩陣,能夠使得所有子載波均能夠獲得全部的分集增益。設(shè)計(jì)了硬件上易于實(shí)現(xiàn)的并行旋轉(zhuǎn)V-OFDM系統(tǒng),通過(guò)優(yōu)化星座圖旋轉(zhuǎn)角度,可在獲得分集增益的同時(shí),進(jìn)一步提高編碼增益。綜合比較了寬帶頻率選擇性衰落信道下接收機(jī)的誤碼率性能和解碼復(fù)雜度,當(dāng)信噪比較低時(shí),可采用最小均方誤差接收機(jī);而當(dāng)信噪比較高時(shí),可采用球形解碼。然后,論文研究了 V-OFDM衛(wèi)星通信與導(dǎo)航一體化系統(tǒng)的可靠傳輸。針對(duì)衛(wèi)星信道傳播距離長(zhǎng)的特點(diǎn),建立了寬帶稀疏頻率選擇性衰落衛(wèi)星信道模型。揭示了稀疏信道的最大多徑分集增益等于非零元素坐標(biāo)對(duì)向量維數(shù)取模運(yùn)算后余數(shù)集合的勢(shì),運(yùn)用數(shù)學(xué)歸納法推導(dǎo)了隨機(jī)信道分集階數(shù)的分布律的閉合表達(dá)式。論文充分利用信道矩陣的稀疏性,提出了部分交集球形解碼接收機(jī),通過(guò)縮小搜索空間降低解碼復(fù)雜度,并推導(dǎo)了球面半徑極限定理。對(duì)于極端情況下候選發(fā)送符號(hào)向量集合為空集時(shí),采用加權(quán)表決思想根據(jù)部分交集球形解碼每次迭代過(guò)程中落入球面半徑內(nèi)的符號(hào)序列集合對(duì)發(fā)送信號(hào)作出判決,克服了部分交集球形解碼在低信噪比條件下難以解碼的缺點(diǎn)。為了適應(yīng)衛(wèi)星信道復(fù)雜快變的特點(diǎn),采用基于加權(quán)表決的部分交集球形解碼接收機(jī)能夠在獲得最大多徑分集增益的同時(shí),盡可能地降低接收機(jī)的解碼復(fù)雜度,實(shí)現(xiàn)業(yè)務(wù)信號(hào)和導(dǎo)航電文的可靠傳輸。最后,論文研究了 V-OFDM衛(wèi)星通信與導(dǎo)航一體化系統(tǒng)的精確定位。采用梳狀導(dǎo)頻結(jié)構(gòu)不僅可以利用均勻分布的導(dǎo)頻信道實(shí)現(xiàn)信道估計(jì),并通過(guò)設(shè)計(jì)最優(yōu)導(dǎo)頻符號(hào)使得信道估計(jì)的均方誤差達(dá)到最小,而且能夠保證數(shù)據(jù)信號(hào)獲得最大多徑分集增益。深入研究了稀疏快速傅里葉變換運(yùn)用散列合并實(shí)現(xiàn)降維過(guò)程,包括其中涉及的兩個(gè)信號(hào)處理方法:置換和加窗濾波,揭示了理想/噪聲環(huán)境信道估計(jì)與狹義/廣義稀疏快速傅里葉逆變換之間的內(nèi)在聯(lián)系。利用導(dǎo)頻信號(hào)實(shí)現(xiàn)碼元同步通常包括捕獲和跟蹤兩個(gè)階段,通過(guò)調(diào)整接收機(jī)快速傅里葉變換滑動(dòng)窗的起始點(diǎn)實(shí)現(xiàn)符號(hào)定時(shí)粗同步,隨后動(dòng)態(tài)調(diào)整傳播時(shí)延估計(jì)實(shí)現(xiàn)精確同步。提出了基于牛頓迭代的多徑時(shí)延最大似然估計(jì)方法,并推導(dǎo)了碼跟蹤精度的克拉美羅界。對(duì)于萊斯衰落衛(wèi)星信道,設(shè)計(jì)了易于實(shí)現(xiàn)的超前/滯后延遲鎖相環(huán)時(shí)延估計(jì)方法。全局最優(yōu)的最大似然位置估計(jì)直接優(yōu)化終端三維位置坐標(biāo),避免了因引入中間變量造成的誤差累積,能夠獲得潛在的星座分集,實(shí)現(xiàn)地面終端的精確定位。論文在全面闡述V-OFDM調(diào)制的基礎(chǔ)上,提出了寬帶衛(wèi)星通信和導(dǎo)航一體化系統(tǒng),設(shè)計(jì)了具有誤碼率低、時(shí)延估計(jì)均方誤差小的接收機(jī)。基于V-OFDM調(diào)制的衛(wèi)星通信與導(dǎo)航一體化系統(tǒng)的提出為實(shí)現(xiàn)可靠傳輸和精確定位奠定了堅(jiān)實(shí)的基礎(chǔ),進(jìn)一步把天地一體化信息網(wǎng)絡(luò)建設(shè)引向深入。
[Abstract]:The satellite communication system and satellite navigation system development today to people's production and life brought great convenience, is also facing the same satellite spectrum resource and serious problems including frequency selective fading channels. At this stage, although the satellite communications and satellite navigation for different application areas, but from the point of view of both the technical level there is a close relationship. On the one hand, related to the error rate of the receiver anti-jamming characteristic and the reliability of navigation satellite communication, thereby affecting the accuracy of the positioning receiver. On the other hand, positioning signals to realize symbol timing synchronization in satellite communication system by estimating the propagation delay, and the synchronization performance directly affects the reliability of communication system so, in the world of integrated information network under the background of the construction of satellite communication and navigation system to make full use of space resources To achieve a multi-purpose star has very important significance. This paper from the basic performance index of the bit error rate of communication and navigation and positioning accuracy of the comprehensive consideration of the utilization of bandwidth, peak to average power ratio and system complexity and other factors, proposed a vector based on orthogonal frequency division multiplexing (V-OFDM) modulation of satellite communication and navigation system, and the channel allocation, pilot design, channel estimation, signal detection, symbol synchronization technology conducted in-depth research, made a series of innovative research results. Firstly, the thesis is on the single carrier frequency domain equalization (SC-FDE) and orthogonal frequency division multiplexing (OFDM) based on their respective advantages and disadvantages, and concluded that the V-OFDM modulation model, and points out that V-OFDM is a bridge connecting the SC-FDE.V-OFDM modulation and OFDM is the idea of a intersymbol interference channel into multiple to the quantum channel, which can be a flexible vector dimension design. However, V-OFDM Modulation cannot obtain diversity gain in a sub carrier signal transmitted by the transmitter is introduced in the constellation rotation matrix, makes all subcarriers can obtain diversity gain. All the hardware design of V-OFDM system to realize the parallel rotation, by optimizing the constellation rotation angle, can achieve the diversity gain at the same time, to further improve the encoding gain. A comprehensive comparison of broadband frequency selective fading channel BER performance and decoding complexity of the receiver, when the SNR is low, the MMSE receiver; and when the SNR is high, the sphere decoding is studied in this paper. Then, the reliable transmission of V-OFDM satellite communication and navigation system according to the characteristics of satellite communication channel. The long distance, the establishment of a satellite broadband frequency selective fading channel model is sparse. The diameter of the sparse channel are revealed 鍒嗛泦澧炵泭絳変簬闈為浂鍏冪礌鍧愭爣瀵瑰悜閲忕淮鏁板彇妯¤繍綆楀悗浣欐暟闆嗗悎鐨勫娍,榪愮敤鏁板褰掔撼娉曟帹瀵間簡(jiǎn)闅忔満淇￠亾鍒嗛泦闃舵暟鐨勫垎甯冨緥鐨勯棴鍚堣〃杈懼紡.璁烘枃鍏呭垎鍒╃敤淇￠亾鐭╅樀鐨勭█鐤忔，

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