本文選題：信道不確實(shí)性 + 香農(nóng)信道容量　； 參考：《浙江大學(xué)》2014年博士論文

【摘要】：本文瞄準(zhǔn)信道不確實(shí)性下的有效、可靠通信,以信息理論、信號處理和傳播物理為支柱,構(gòu)建通信問題中的最佳瞬態(tài)觀察者,即逼近香農(nóng)信道容量限的Turbo通信系統(tǒng)。結(jié)合傳播物理,研究動態(tài)稀疏時延—多普勒雙擴(kuò)展信道的解卷估計(jì)問題,這屬于欠定逆問題的求解。在此基礎(chǔ)上,設(shè)計(jì)了雙擴(kuò)展信道估計(jì)與判決迭代均衡相協(xié)同的水聲通信系統(tǒng),提高了雙擴(kuò)展條件下的通信性能。由于空時陣可以通過復(fù)用與分集對信道容量、系統(tǒng)通信差錯率等性能帶來質(zhì)的提升,因此從估計(jì)理論與信息理論相結(jié)合的角度,提出了作為最佳瞬變觀察者的空-時-頻廣義旁瓣抵消器,實(shí)現(xiàn)了信道不確實(shí)條件下的有效、可靠通信。 Turbo通信系統(tǒng)是一個逼近香農(nóng)信道容量限的最佳瞬態(tài)觀察者。Turbo原理可以公式化為：采用迭代更新的外信息作為先驗(yàn)信息對符號和碼進(jìn)行序貫貝葉斯估計(jì)。Turbo原理實(shí)質(zhì)上由：(1)狀態(tài)—空間模型(2)新息過程(3)反饋三要素組成,因而是通信問題中的最佳瞬態(tài)觀察者。為了研究Turbo通信系統(tǒng)的有效性,首先需要回答的是通信性能限的問題,即：在給定信道環(huán)境中最終能達(dá)到的可靠通信傳輸率是多少。香農(nóng)信道容量定理表明,存在通信系統(tǒng)能達(dá)到信道容量限,且該容量限是緊致的,因此信道容量提供了一個標(biāo)準(zhǔn)來量化地衡量Turbo通信系統(tǒng)的性能。在本文所給出的例子中,Turbo通信系統(tǒng)僅與信道容量所預(yù)測的最小可靠通信信噪比相差1.4dB,體現(xiàn)了Turbo通信系統(tǒng)的有效性。 Turbo通信系統(tǒng)在雙擴(kuò)展信道下的具體運(yùn)用,需要傳播物理來推動。本文從波動方程出發(fā),分析了稀疏時延—多普勒雙擴(kuò)展信道的物理成因,以波數(shù)積分法推導(dǎo)出波導(dǎo)環(huán)境中運(yùn)動聲源產(chǎn)生的聲場物理表達(dá)式。由于深度分離格林函數(shù)僅在少數(shù)幾個水平波數(shù)值處有較大的非零值,從而在物理源頭就保證了信道在時延—多普勒維度上的稀疏性。時延—多普勒雙擴(kuò)展信道的解卷估計(jì)是一個欠定逆問題,常規(guī)的過定最小二乘方法失效,有無窮多個解。傳播物理所導(dǎo)出的信道稀疏性這一物理先驗(yàn),為約束優(yōu)化方法開發(fā)利用并對解空間施以約束,使得欠定逆問題可解,其性能優(yōu)于正向匹配求解逆問題的互模糊度函數(shù)方法,因?yàn)檎龁栴}方法沒有利用該物理先驗(yàn)。由于海表面波和內(nèi)波等因素的影響,時延—多普勒雙擴(kuò)展信道還具有動態(tài)特性,需要開發(fā)對信道的稀疏序貫估計(jì)理論。本文為了實(shí)現(xiàn)動態(tài)稀疏雙擴(kuò)展信道的序貫估計(jì)方法,將約束優(yōu)化問題等價為求各約束集的交集問題。每個時刻的接收序列會產(chǎn)生一個新的約束集,并且以不斷往約束集上投影的方法最終收斂于信道的真實(shí)解。 在解決了動態(tài)稀疏時延—多普勒雙擴(kuò)展信道估計(jì)問題的基礎(chǔ)上,設(shè)計(jì)了雙擴(kuò)展信道估計(jì)與判決迭代均衡相協(xié)同的水聲通信系統(tǒng)。水聲通信向來將信道的時延—多普勒雙擴(kuò)展及其變化視為其最大的挑戰(zhàn),傳統(tǒng)基于多普勒頻移補(bǔ)償?shù)南喔赏ㄐ偶夹g(shù)并不能在時延—多普勒雙擴(kuò)展信道中實(shí)現(xiàn)可靠通信。第一個結(jié)合試圖將雙擴(kuò)展信道視為機(jī)遇并由此獲取處理增益。由此得到的新處理器可視作水聲雙擴(kuò)展信道下的最佳瞬態(tài)觀察者,在該信道中能夠?qū)崿F(xiàn)有效、可靠通信。從處理器結(jié)構(gòu)上看,其均衡器部分在時—頻兩維上實(shí)現(xiàn)接收分集,可以可靠工作在時延—多普勒雙擴(kuò)展信道下；而均衡器與解碼器之間的新息迭代又極大地降低系統(tǒng)的誤符號率和誤碼率,使之逼近香農(nóng)信道容量限,從而具有通信的有效性。 在實(shí)現(xiàn)了第一個結(jié)合的基礎(chǔ)上,本文進(jìn)一步研究空時Turbo通信系統(tǒng)。首先要回答的問題是為什么要空時陣,為什么要與空時陣系統(tǒng)相結(jié)合。本文從多個角度回答了這一問題。首先推導(dǎo)了衰落信道下空時陣通信系統(tǒng)的通信差錯概率為：P(error)～Gc·SNR-Gd (1)其中編碼增益Gc提供的是乘性增益,而由空時陣通信系統(tǒng)所帶來的分集增益Gd則體現(xiàn)在使得通信差錯概率隨信噪比上升而指數(shù)下降上,顯然要提供比編碼增益可觀得多的性能改善。對本文所研究的動態(tài)時延—多普勒雙擴(kuò)展信道下的空時Turbo陣通信系統(tǒng)而言,推導(dǎo)得出Gd∝nrnt(M+1)L,即從發(fā)射、接收、多路徑和頻率四維分集來提高系統(tǒng)系能。因此從可靠性即對系統(tǒng)通信差錯概率的控制上,發(fā)展空時Turbo陣通信系統(tǒng)將帶來非常可觀的好處。從香農(nóng)信道容量的角度看來,空時陣通信系統(tǒng)可以通過復(fù)用使得信道容量隨著有效信道數(shù)目呈線性比例增長；也可以通過分集使得衰落信道中斷容量為一定時的中斷概率指數(shù)下降。既然空時陣通信系統(tǒng)可以通過復(fù)用與分集對通信系統(tǒng)的有效性與可靠性帶來質(zhì)的提升,因此有必要實(shí)現(xiàn)雙擴(kuò)展信道下的空時Turbo通信系統(tǒng)。 為了使最佳陣處理系統(tǒng)可靠地工作在雙擴(kuò)展信道下,將最佳陣處理器的等價形式—廣義旁瓣抵消器推廣至?xí)r延—多普勒雙擴(kuò)展信道,得到空—時—頻廣義旁瓣抵消器,通信系統(tǒng)通過空間—時延—頻率分集與復(fù)用來極大地提高通信速率和可靠性。從估計(jì)理論與信息理論相結(jié)合的角度,提出雙擴(kuò)展信道下的空時Turbo陣通信系統(tǒng)。該處理器的特點(diǎn)可以歸納為：(1)將信道的時延—多普勒雙擴(kuò)展特性顯式地考慮到處理器框架中,利用雙擴(kuò)展信道下的空—時—頻廣義旁瓣抵消器通過在空—時—頻多維的相干分集來增強(qiáng)信號,抑制符號間干擾和同道干擾；由于同道干擾的問題得到了妥善的解決,因而可以通過信道的復(fù)用來極大提高通信系統(tǒng)的通信速率,保證了通信的有效性。(2)Turbo通信系統(tǒng)是逼近香農(nóng)信道容量的最佳瞬態(tài)觀察者。正是由于Turbo機(jī)制的引入,系統(tǒng)的穩(wěn)定性通過嵌入在發(fā)送碼字中的結(jié)構(gòu)性知識來保證。(3)空—時—頻廣義旁瓣抵消器其陣駕駛向量是信道估計(jì)結(jié)果的函數(shù),通過Turbo系統(tǒng)的迭代進(jìn)行,信道估計(jì)的結(jié)果會隨之改善,進(jìn)一步提高陣處理的性能。 綜上所述,本文的創(chuàng)新點(diǎn)可以歸納為：(1)結(jié)合水聲傳播物理,分析研究了雙擴(kuò)展信道響應(yīng)的稀疏性,提出了基于稀疏約束的雙擴(kuò)展信道序貫估計(jì)-跟蹤方法,可有效應(yīng)用于時變信道條件下的水聲通信。(2)設(shè)計(jì)了雙擴(kuò)展信道估計(jì)與判決迭代均衡相協(xié)同的水聲通信系統(tǒng),提高了雙擴(kuò)展條件下的通信性能。(3)從估計(jì)理論與信息理論相結(jié)合的角度,提出了作為最佳瞬變觀察者的空-時-頻廣義旁瓣抵消器,實(shí)現(xiàn)了信道不確實(shí)條件下的有效、可靠通信。 本文主要章節(jié)按創(chuàng)新點(diǎn)分為三部分,第一部分詳述了稀疏雙擴(kuò)展信道的物理成因,互模糊度函數(shù)信道估計(jì)方法與約束優(yōu)化估計(jì)方法,動態(tài)時延—多普勒稀疏雙擴(kuò)展信道的序貫壓縮重構(gòu)方法,為后續(xù)章節(jié)打下信道估計(jì)前處理的基礎(chǔ)；第二部分研究了通信問題中的最佳瞬態(tài)觀察者,即Turbo通信系統(tǒng),并通過與香農(nóng)信道容量的比較分析了其有效性。得到了雙擴(kuò)展信道下的Turbo通信系統(tǒng)；第三部分研究了空時陣通信系統(tǒng)對通信有效性和可靠性的巨大提升,提出了能可靠工作在雙擴(kuò)展信道下的空—時—頻廣義旁瓣抵消器,得到本文最終的題目內(nèi)容：水聲雙擴(kuò)展信道下的空時Turbo陣通信系統(tǒng)。仿真和海試實(shí)驗(yàn)數(shù)據(jù)分析驗(yàn)證了系統(tǒng)的可靠性和有效性。
[Abstract]:In this paper, we aim at the effective and reliable communication under the inaccuracy of the channel, with information theory, signal processing and propagation physics as the backbone to construct the best transient observer in the communication problem, that is, the Turbo communication system approaching the Shannon channel capacity limit. This is a solution to the undetermined inverse problem. On this basis, a underwater acoustic communication system with double extended channel estimation and iterative equalization is designed to improve the communication performance under the condition of double expansion. Because the space time matrix can improve the performance of the channel capacity and the error rate of the system communication through multiplexing and diversity, the estimation of the performance of the system is improved. With the combination of theory and information theory, an empty time frequency generalized sidelobe canceller, which is the best transient observer, is proposed to achieve effective and reliable communication under the untrue channel condition.
The Turbo communication system is an optimal transient observer that approximating the Shannon channel capacity limit.Turbo principle can be formulated as: the sequential Bayesian estimation of symbols and codes by iterative and updated information as prior information is essentially composed of the (1) state space model (2) new interest process (3) feedback three elements. It is the best transient observer in the communication problem. In order to study the effectiveness of the Turbo communication system, the first thing to answer is the problem of the communication performance limit, that is, what is the reliable communication transmission rate that can eventually be achieved in a given channel environment. The Shannon channel capacity theorem shows that the communication system can reach the channel capacity limit and the capacity of the communication system. The limit is compact, so the channel capacity provides a standard to quantify the performance of the Turbo communication system. In the example presented in this paper, the Turbo communication system is only 1.4dB of the minimum reliable communication signal to noise ratio predicted by the channel capacity, which reflects the effectiveness of the Turbo communication system.
The specific application of the Turbo communication system in the double spread channel requires the propagation of physics. This paper analyzes the physical causes of the sparse delay Doppler double propagation channel from the wave equation, and derives the physical expression of the sound field generated by the moving sound source in the waveguide environment by the wave number integral method. Because the depth separation of the Green function is only less. Several horizontal wave values have large non zero values, thus ensuring the sparsity of the channel in the time delay - Doppler dimension at the physical source. The deconvolution estimation of the time delay - Doppler double expansion channel is an underdetermined inverse problem. The conventional overdetermined least squares method is invalid and there are infinitely many solutions. The channel sparsity derived from the propagation physics The physical prior is developed and utilized for constrained optimization methods and constrained to the solution space, which makes the undetermined inverse problem solvable, and its performance is better than the reciprocal ambiguity function method for the forward matching to solve the inverse problem, because the positive problem method does not use the physical prior. Due to the influence of the sea surface wave and internal wave, time delay Doppler double The extended channel also has dynamic characteristics and needs to develop the sparse sequential estimation theory for channels. In order to realize the sequential estimation of the dynamic sparse and double extended channel, the constrained optimization problem is equivalent to the intersection problem of each constraint set. The receiving sequence at each time will produce a new constraint set and to the constraint set. The projection method finally converges to the true solution of the channel.
On the basis of solving the problem of dynamic sparse delay Doppler double propagation channel estimation, a underwater acoustic communication system with dual extended channel estimation and iterative equalization is designed. Underwater acoustic communication has always considered the time delay of the channel - Doppler double expansion and its change as its biggest challenge, and the traditional phase based on Doppler frequency shift compensation The dry communication technology can not achieve reliable communication in the time delay Doppler double spread channel. The first combination tries to see the dual extended channel as an opportunity and thus obtain the processing gain. The resulting new processor can be considered as the best transient observer in the underwater acoustic dual propagation channel, which can be effective and reliable communication in this channel. In view of the structure, the equalizer part realizes the reception diversity on the time frequency two dimension. It can work reliably under the delay Doppler double expansion channel, while the new interest iteration between the equalizer and the decoder greatly reduces the system's false symbol rate and the bit error rate, making it close to the Shannon channel capacity limit and thus has the effectiveness of the communication.
On the basis of the first combination, this paper further studies space-time Turbo communication systems. The first question to answer is why the space-time matrix is needed and why it should be combined with the space-time matrix system. This paper answers this problem from many angles. Firstly, the error probability of the space time matrix communication system under the fading channel is P (ER ROR) ~ Gc. SNR-Gd (1) the encoding gain Gc provides multiplicative gain, and the diversity gain Gd brought by the space-time matrix communication system is reflected in the exponential decline of the probability of communication error with the signal to noise ratio, obviously providing a much greater performance improvement than the coding gain. The dynamic delay of this paper has been studied by Doppler double. For the space-time Turbo array communication system under the extended channel, the Gd nrnt (M+1) L is derived from the transmission, reception, multipath and frequency four dimension diversity to improve the system power. Therefore, the development of the space-time Turbo matrix communication system will bring a very considerable benefit from the reliability and the control of the error probability of the system communication. From the Shannon channel capacity The space time matrix communication system can increase the capacity of the channel with the number of effective channels in a linear proportion, and can also reduce the interruption probability index when the interruption capacity of the fading channel is certain by diversity. Since the space time matrix communication system can be effective and reliable by the reuse and diversity of the communication system. Because of the qualitative improvement, it is necessary to realize the space-time Turbo communication system under dual extended channels.
In order to make the best array processing system work reliably in the double spread channel, the equivalent form of the optimal array processor is extended to the delay Doppler double extension channel, and the space-time frequency generalized sidelobe canceller is obtained. The communication system improves the communication speed greatly through the spatial time delay frequency diversity and multiplexing. Rate and reliability. A space-time Turbo matrix communication system with double extended channels is proposed from the combination of estimation theory and information theory. The characteristics of this processor can be summed up as follows: (1) the time delay and Doppler double expansion characteristics of the channel are explicitly considered in the processor framework and the space-time frequency broad sidelobe under the dual extended channel is used. The canceller enhances the signal through the coherent diversity of the space-time frequency multidimensional diversity to suppress the inter symbol interference and the channel interference. Because the problem of the channel interference is properly solved, the communication rate of the communication system can be greatly improved through the multiplexing of the channel, and the effectiveness of the communication is guaranteed. (2) Turbo communication system is an approximation of the incense. The best transient observer of the capacity of the agricultural channel is due to the introduction of the Turbo mechanism. The stability of the system is guaranteed by the structural knowledge embedded in the transmission code. (3) the driving vector of the space-time generalized sidelobe is a function of the channel estimation result. The result of the channel estimation will follow the iteration of the Turbo system. The improvement will further improve the performance of the array processing.
To sum up, the innovative points of this paper can be summed up as follows: (1) the sparsity of dual propagation channel response is analyzed and studied in combination with underwater acoustic propagation physics. A double extended channel sequential estimation and tracking method based on sparse constraints is proposed, which can be effectively applied to underwater acoustic communication under the condition of time-varying channel. (2) a double extended channel estimation and decision iteration is designed. The underwater acoustic communication system with equilibrium phase synergy improves the communication performance under the condition of double expansion. (3) an empty time frequency generalized sidelobe canceller, which is the best transient observer, is proposed from the angle of combination of the estimation theory and information theory, and the effective and reliable communication under the untrue channel condition is realized.
The main section of this paper is divided into three parts. In the first part, the physical origin of the sparse double propagation channel, the channel estimation method and the constraint optimization estimation method of the cross ambiguity function, the sequential compression reconstruction method of the dynamic delay Doppler sparse double extension channel are discussed, and the foundation of the channel estimation is laid down for the later section. The two part studies the best transient observer in the communication problem, namely the Turbo communication system, and analyzes its effectiveness by comparing with the capacity of the Shannon channel. The Turbo communication system under the double expansion channel is obtained. The third part studies the great improvement of the communication effectiveness and reliability of the space time array communication system, and puts forward the reliable work. An air time frequency generalized sidelobe offset receiver under the double spread channel is used to obtain the final topic of this paper: the space time Turbo array communication system under the underwater acoustic dual expansion channel. The simulation and experimental data analysis of the sea test verify the reliability and effectiveness of the system.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TN929.3

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本文編號：1983937