本文選題：車輛自組網(wǎng) + 物理層�。� 參考：《東南大學(xué)》2016年博士論文

【摘要】：隨著無線通信技術(shù)的日益普及和對(duì)其它技術(shù)領(lǐng)域的廣泛滲透,汽車制造業(yè)正在積極尋求利用無線通信技術(shù)提升市場(chǎng)競(jìng)爭(zhēng)優(yōu)勢(shì)的方案。本文中,車輛自組網(wǎng)(VANET)已有諸多應(yīng)用,例如安全、救援、勘探、軍事、人口稀疏地的冗余通信、以及作為智能交通系統(tǒng)(ITS)重要組成部分的傳統(tǒng)城市及高速公路通信。不過,這一技術(shù)的滲透尚顯不足,仍有大量問題亟待解決,以建造彈性、可靠、高效的車輛自組網(wǎng)。通信服務(wù)質(zhì)量(QoC)主要取決于物理層(PHY)的可靠性,其中包含了VANET中各類頗有挑戰(zhàn)性的問題。車輛的高速運(yùn)動(dòng)會(huì)導(dǎo)致VANET中的大量碎片化和拓?fù)洳欢ㄐ浴HY的性能是提升通信質(zhì)量的一個(gè)關(guān)鍵因素。物理層需要解決有限帶寬、應(yīng)用需求以及不穩(wěn)定和碎片化的網(wǎng)絡(luò)拓?fù)�。本文主要研究物理�?包括與VANET應(yīng)用相關(guān)的問題、挑戰(zhàn)及研究機(jī)遇。主要貢獻(xiàn)和創(chuàng)新如下：1.提出了通過理論途徑顯著提升車輛網(wǎng)絡(luò)通信性能的方法,即在不改變帶寬、費(fèi)用及系統(tǒng)復(fù)雜度的前提下,提升物理層OFDM系統(tǒng)的性能。本文提出了一種通用模型來描述車輛通信場(chǎng)景的物理層傳輸技術(shù),能夠解決車輛通信中一些具有挑戰(zhàn)性的問題,并從理論上探究不同傳輸場(chǎng)景下的通信效果。物理層的傳輸過程包含了諸多復(fù)雜步驟,本文模型對(duì)其均有涉及。該模型對(duì)應(yīng)著IEEE 802.11p的物理層結(jié)構(gòu),也描述了車輛網(wǎng)絡(luò)中的無線信道特征,并發(fā)展了用參數(shù)化形式描述信道最重要特征的簡(jiǎn)化信道模型。該模型隨后將用于評(píng)估系統(tǒng)性能并研究物理層的挑戰(zhàn),以提升車輛網(wǎng)的總體通信效率。2.應(yīng)用代數(shù)lattice理論及其它數(shù)學(xué)工具改進(jìn)OFDM系統(tǒng),從而直接提升了整個(gè)VANET物理層的性能。為了改進(jìn)通信的可靠性,采用order理論和Hamming距離,提出了一種適用于車輛網(wǎng)絡(luò)的高階OFDM分集方案,其頻域分集通過在傳輸符號(hào)中規(guī)定特定的相關(guān)性來實(shí)現(xiàn)。由于子信道歷經(jīng)獨(dú)立衰落,至少有一個(gè)符號(hào)擁有可靠的信噪比,接收機(jī)可利用該符號(hào)來檢測(cè)其它符號(hào)。3.研究了利用最小二乘(LS)和最小均方誤差(MMSE)的信道估計(jì)器,發(fā)展了一種提高VANET物理層通信性能的新方法。該方法通過將DFT和SVD與LS和MMSE相結(jié)合,提升了系統(tǒng)性能,并降低了系統(tǒng)復(fù)雜度。4.針對(duì)車輛網(wǎng)絡(luò)提出了一種新型的符號(hào)同步技術(shù),即利用不同OFDM子載波之間的功率差異和定時(shí)誤差導(dǎo)致的相移。該方案采用3種方法最小化由于符號(hào)時(shí)間偏移導(dǎo)致的子載波干擾(ICI)和碼間干擾(ISI)。第一種方法通過第一個(gè)OFDM接收符號(hào)來檢測(cè)由定時(shí)誤差而導(dǎo)致的子載波相移,以此來估計(jì)時(shí)移,即利用了時(shí)移導(dǎo)致的相移來估計(jì)定時(shí)誤差,故本文稱其為相移估計(jì)器(PSME);第二種方案最小化相鄰子載波在同一OFDM符號(hào)內(nèi)的功率差異,假設(shè)了這些子載波的信道響應(yīng)近似相同。因其僅在頻域利用子信道,故稱為頻域累計(jì)功率差異估計(jì)器(FD-APDE);第三種方案通過測(cè)量相鄰OFDM符號(hào)的等下標(biāo)的子載波功率差異,假設(shè)了信道在兩個(gè)相鄰OFDM符號(hào)之間是緩變的,故叫做時(shí)域累計(jì)功率誤差估計(jì)器(TD-APDE)。這3種估計(jì)器均為全盲估計(jì),因?yàn)榻邮斩藳]有任何關(guān)于發(fā)送數(shù)據(jù)或者信道狀態(tài)(CSI)的信息,但這些信息能夠極大地提高估計(jì)器的性能。為了在不同的VANET場(chǎng)景提供定時(shí)同步,這些估計(jì)器能夠組合與互補(bǔ)應(yīng)用。5.利用物理層的內(nèi)在隨機(jī)性來提高車輛網(wǎng)絡(luò)的安全性。探索了利用通常被視作不利因素的噪聲和干擾作為提高安全性的隨機(jī)因子的可能,提出了一種針對(duì)車輛網(wǎng)絡(luò)的密鑰生成方法,其利用了無線信道本身的隨機(jī)特性。把由于車輛移動(dòng)、噪聲、多徑衰落而導(dǎo)致的接收信號(hào)場(chǎng)強(qiáng)(RSS)變化量化后用來生成密鑰。仿真結(jié)果顯示該算法尤其適合VANET,因?yàn)閂ANET的多種工作環(huán)境比其它通信系統(tǒng)的隨機(jī)性更強(qiáng)。本文算法能夠提取高熵率的高速或低速密鑰,且合法車輛間的信息交換量更少。該密鑰能夠用于諸多安全系統(tǒng)以支持VANET服務(wù)的安全性。
[Abstract]:With the increasing popularity of wireless communication technology and the widespread penetration of other technology fields, the automobile manufacturing industry is actively seeking a scheme to improve the competitive advantage of the market by using wireless communication technology. In this paper, the vehicle ad hoc network (VANET) has many applications, such as security, rescue, exploration, military, sparse population of redundant communications, and as The important components of the intelligent transportation system (ITS) are the traditional city and the expressway communication. However, the penetration of this technology is still insufficient. There are still a lot of problems to be solved to build an elastic, reliable and efficient vehicle ad hoc network. The quality of communication (QoC) depends mainly on the reliability of the physical layer (PHY), which includes the various types of VANET. Challenging problems. High speed movement of vehicles will lead to a large number of fragmentation in VANET and the performance of topology uncertainty.PHY is a key factor in improving communication quality. The physical layer needs to solve the limited bandwidth, application requirements, and the unstable and fragmented network topology. This paper mainly studies the physical layer, including the questions related to the VANET application. Problems, challenges and research opportunities. Main contributions and innovations are as follows: 1. a method of improving vehicle network communication performance by means of theoretical approaches is proposed, that is, to improve the performance of the physical layer OFDM system without changing the bandwidth, cost and system complexity. A general model is proposed to describe the physical layer of vehicle communication scenes. Transmission technology can solve some challenging problems in vehicle communication, and explore the communication effect in different transmission scenarios. The transmission process of the physical layer contains many complex steps. This model is involved in the model. The model corresponds to the physical layer structure of IEEE 802.11p and the wireless network in the vehicle network. A simplified channel model is developed to describe the most important characteristics of the channel by parameterized form. This model will be used to evaluate the performance of the system and study the challenges of the physical layer to improve the overall communication efficiency of the vehicle network.2. application algebra lattice theory and other mathematical tools to improve the OFDM system, thus improving the whole VANET directly. In order to improve the reliability of communication, in order to improve the reliability of communication, a high order OFDM diversity scheme suitable for vehicle networks is proposed by using order theory and Hamming distance. The frequency diversity is realized by specific correlation in the transmission symbols. At least one symbol has a reliable SNR because of the subchannel failure. The receiver can use this symbol to detect other symbols.3. to study the channel estimator using the least square (LS) and least mean square error (MMSE), and develops a new method to improve the communication performance of the VANET physical layer. By combining DFT and SVD with LS and MMSE, the system performance is enhanced and the system complexity.4. is reduced to the vehicle. The network proposes a new symbol synchronization technique, which uses the power difference and the timing error between different OFDM subcarriers. The scheme uses 3 methods to minimize the subcarrier interference (ICI) and Intercode interference (ISI) due to the symbol time offset. The first method is to detect by the first OFDM receiving symbol. The subcarrier phase shift caused by the timing error is used to estimate the time shift, that is, the phase shift caused by the time shift is used to estimate the timing error, so this paper is called the phase shift estimator (PSME); the second scheme minimizes the power difference between the adjacent subcarriers in the same OFDM symbol, assuming that the channel responses of these subcarriers are approximately the same because they are only in the same way. Using subchannels in frequency domain, it is known as the frequency domain cumulative power difference estimator (FD-APDE); the third scheme is called the time domain cumulative power error error estimator (TD-APDE) by measuring the subcarrier power difference between the adjacent OFDM symbols, which is called the time domain cumulative power error error estimator (TD-APDE). All of the 3 estimators are all blind. Because the receiver does not have any information about sending data or channel state (CSI), these information can greatly improve the performance of the estimator. In order to provide timing synchronization in different VANET scenarios, these estimators can combine and complementary application.5. to improve the security of the vehicle network using the intrinsic randomness of the physical layer. By using the noise and interference usually considered as adverse factors as a possibility to improve the random factors of security, a key generation method for vehicle networks is proposed, which takes advantage of the random characteristics of the wireless channel itself. It is used to quantify the change of the received signal field intensity (RSS) due to vehicle movement, noise and multipath fading. The simulation results show that the algorithm is especially suitable for VANET, because the multiple working environment of VANET is more random than other communication systems. This algorithm can extract high entropy high speed or low speed key and less information exchange between legitimate vehicles. This key can be used in many security systems to support VANET services. Full.

【學(xué)位授予單位】：東南大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：TN929.5
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本文編號(hào)：1776485