本文選題：認(rèn)知無線網(wǎng)絡(luò) + OFDM��； 參考：《北京郵電大學(xué)》2014年博士論文

【摘要】：智能終端的大量引入以及各式應(yīng)用的快速涌現(xiàn),給無線網(wǎng)絡(luò)帶來了前所未有的機(jī)遇與挑戰(zhàn)。頻譜利用率低下與頻譜資源稀缺的矛盾日益激化,亟需全新的頻譜分配與利用技術(shù)更智能地使用頻譜資源。認(rèn)知無線電(Cognitive Radio, CR)很好地契合了該需求,引起了學(xué)術(shù)界和工業(yè)界的廣泛關(guān)注。認(rèn)知獲得的頻譜具有零散性、碎片化特征,而正交頻分復(fù)用技術(shù)(Orthogonal Frequency Division Multiplexing, OFDM)技術(shù)在資源利用方面具有的靈活性剛好滿足了認(rèn)知無線網(wǎng)絡(luò)的技術(shù)需求。同時越來越多的應(yīng)用需要向特定的用戶群發(fā)送特定的信息,此時采用多播技術(shù),將對同一內(nèi)容感興趣的用戶作為一個多播組,為其提供多播業(yè)務(wù),大大降低了連接用戶數(shù)與所需系統(tǒng)資源的線性依賴性,使得相同的無線網(wǎng)絡(luò)資源能夠服務(wù)更多的用戶,獲得運(yùn)營商和用戶雙贏的局面。因此,在基于OFDM的認(rèn)知無線網(wǎng)絡(luò)中有效開展多播業(yè)務(wù)是未來無線通信系統(tǒng)發(fā)展的一大趨勢,具有重要的意義。 盡管認(rèn)知無線網(wǎng)絡(luò)與多播技術(shù)具有諸多優(yōu)點(diǎn),但是實(shí)際性能的提升則主要取決于資源分配方案的設(shè)計(jì)與選擇。因此,高效而實(shí)用的資源分配方案是基于OFDM的認(rèn)知無線多播網(wǎng)絡(luò)提高系統(tǒng)頻譜效率、保證用戶QoS性能的關(guān)鍵。目前,在基于OFDM的認(rèn)知無線網(wǎng)絡(luò)方面,大部分研究針對單播資源分配展開；少數(shù)文獻(xiàn)研究了傳統(tǒng)多播資源分配,得到了一些有用的結(jié)果,但是傳統(tǒng)多播的性能受限于多播組中性能最差的用戶,不能充分發(fā)揮無線多播的技術(shù)優(yōu)勢。而編碼多播,將多播數(shù)據(jù)進(jìn)行統(tǒng)一的信源編碼,使得編碼后的數(shù)據(jù)具有質(zhì)量可擴(kuò)展性,接收到的數(shù)據(jù)越多,最終解碼以后恢復(fù)出來的數(shù)據(jù)質(zhì)量越高,從而其性能不再受限于最差用戶,基站可以根據(jù)用戶信道條件的差異實(shí)現(xiàn)彈性多播,為用戶提供更優(yōu)質(zhì)的多播業(yè)務(wù),在通信系統(tǒng)中具有良好的應(yīng)用前景。而目前針對編碼多播資源分配研究幾乎屬于空白�？紤]到認(rèn)知無線網(wǎng)絡(luò)面臨的全新挑戰(zhàn),以及編碼多播的技術(shù)難點(diǎn),傳統(tǒng)的資源分配方案已經(jīng)難以滿足其需求,如何設(shè)計(jì)新的方案極具挑戰(zhàn)。 本文將認(rèn)知無線蜂窩網(wǎng)絡(luò)與OFDM技術(shù)以及編碼多播技術(shù)結(jié)合,針對基于OFDM的認(rèn)知無線網(wǎng)絡(luò)編碼多播資源分配問題,按從簡單到復(fù)雜、從理想到實(shí)際的循序漸進(jìn)方式逐步深化系統(tǒng)資源分配模型與方法的研究,取得了一些具有一定理論價值與實(shí)際意義的研究成果。 第一,本文在第三章分析了認(rèn)知無線網(wǎng)絡(luò)編碼多播的極限性能。由于在大多數(shù)場景下,考慮無線傳輸?shù)膹?fù)雜性,以及認(rèn)知無線網(wǎng)絡(luò)的特殊性,精確的性能分析可能會推導(dǎo)出極其復(fù)雜的數(shù)學(xué)表達(dá)式,很難從中發(fā)現(xiàn)有用的規(guī)律,獲得有用的指導(dǎo)信息,因此本文利用極值理論,對認(rèn)知無線網(wǎng)絡(luò)場景下采用單播、傳統(tǒng)多播和多描述編碼多播傳輸公共數(shù)據(jù)業(yè)務(wù)的漸進(jìn)吞吐量性能進(jìn)行了分析和比較。仿真結(jié)果表明,即使在用戶數(shù)不是很大的情形下漸進(jìn)分析結(jié)果也很精確。同時,理論分析和仿真結(jié)果都表明在認(rèn)知場景下,多描述編碼多播相比單播和傳統(tǒng)多播具有巨大的優(yōu)勢,因此在認(rèn)知無線網(wǎng)絡(luò)中使用多描述編碼多播進(jìn)行公共數(shù)據(jù)的傳輸具有很大的意義,進(jìn)一步驗(yàn)證了本論文研究工作的重要性,也為設(shè)計(jì)資源分配算法提供了理論指導(dǎo)。 第二,本文在第四章設(shè)計(jì)了基于統(tǒng)計(jì)信道狀態(tài)信息的多描述編碼多播方案。在之前的理想模型中,假設(shè)次基站在執(zhí)行資源分配時總是知道所有信道的精確信息,但是信道的估計(jì)誤差、反饋時延、量化誤差等不完美因素將制約系統(tǒng)性能的提升,另外在多播用戶數(shù)較多時,進(jìn)行頻繁地信道信息反饋將不切實(shí)際。本文針對認(rèn)知無線網(wǎng)絡(luò)的特點(diǎn),研究了非理想信道下的編碼多播資源分配,利用概率統(tǒng)計(jì)、隨機(jī)過程、序統(tǒng)計(jì)理論進(jìn)行理論推導(dǎo),設(shè)計(jì)了一種次基站僅有統(tǒng)計(jì)信道狀態(tài)信息的多描述編碼多播方案,所提方案能以低復(fù)雜度逼近最優(yōu)性能,具有較好的實(shí)用價值。 第三,本文在第五章和第六章設(shè)計(jì)了多小區(qū)編碼多播的資源分配方案。由于實(shí)際系統(tǒng)中,一個小區(qū)并非孤立地存在,多小區(qū)共存是目前主流蜂窩系統(tǒng)的組網(wǎng)方式,因此有必要研究多小區(qū)場景的多播資源分配。對于基于OFDM的認(rèn)知無線網(wǎng)絡(luò),多小區(qū)場景需要考慮小區(qū)間的同頻干擾問題,相比單小區(qū)場景更加復(fù)雜,目前公開發(fā)表的文獻(xiàn)鮮有涉及多小區(qū)多播資源分配。本文首先分析了多小區(qū)編碼多播的理論性能,接下來借鑒博弈論、幾何規(guī)劃、對偶分解等方面的理論和方法,結(jié)合本文特定的場景,提出了兩種低復(fù)雜度分布式算法,既避免了集中資源分配的高計(jì)算復(fù)雜度,又減小了小區(qū)間的反饋開銷,在性能與復(fù)雜度之間取得了良好折中。
[Abstract]:The large number of intelligent terminals and the rapid emergence of various applications have brought unprecedented opportunities and challenges to wireless networks. The contradiction between low frequency spectrum utilization and the scarcity of spectrum resources is becoming more and more urgent, and a new spectrum allocation and utilization technology is urgently needed to use the spectrum resources more intelligently. Cognitive radio (Cognitive Radio, CR) is very good. The demand has attracted wide attention from the academia and the industry. The spectrum of cognitive acquisition has fragmentary and fragmented features, and the flexibility of Orthogonal Frequency Division Multiplexing (OFDM) technology has just met the technical requirements of the cognitive wireless network. The more applications need to send specific information to a specific user group, using multicast technology to provide multicast service to the users of the same content as a multicast group, which greatly reduces the linear dependence of the number of connected users and the required system resources, making the same wireless network resources more capable of serving more. Users can win a win-win situation between the operators and the users. Therefore, the effective development of multicast service in the OFDM based cognitive wireless network is a major trend in the development of future wireless communication systems, which is of great significance.
Although the cognitive wireless network and multicast technology have many advantages, the improvement of actual performance mainly depends on the design and selection of the resource allocation scheme. Therefore, the efficient and practical resource allocation scheme is based on the OFDM based cognitive wireless multicast network to improve the efficiency of the system spectrum and ensure the performance of the user QoS. At present, it is based on OFDM In the cognitive wireless network, most of the research focuses on unicast resource allocation; a few documents study the traditional multicast resource allocation and get some useful results. However, the performance of the traditional multicast is limited to the worst performance users in the multicast group, and it can not give full play to the technical advantage of wireless multicast. According to the unified source code, the encoded data has the quality extensibility, the more the received data, the higher the quality of the data recovered after the final decoding, and the performance is no longer limited to the worst users. The base station can implement elastic multicast according to the difference of the user channel conditions and provide the users with better multicast. Business has a good application prospect in the communication system. At present, the research on the allocation of coded multicast resources is almost blank. Considering the new challenges faced by the cognitive wireless network and the technical difficulties of coding multicast, the traditional resource allocation scheme has been difficult to meet its needs. It is very challenging to design a new scheme.
In this paper, we combine the cognitive wireless cellular network with OFDM technology and coded multicast technology. In view of the OFDM based multicast resource allocation problem in cognitive wireless network, the research on the system resource allocation model and the square method is gradually deepened from the ideal to the practical step by step, from the simple to the complex, and some theoretical prices have been obtained. Research results of value and practical significance.
First, in the third chapter, the ultimate performance of the cognitive wireless network coding multicast is analyzed. In most scenarios, considering the complexity of wireless transmission and the particularity of the cognitive wireless network, accurate performance analysis may derive extremely complex mathematical expressions. It is difficult to find useful rules from which useful fingers can be obtained. In this paper, we use extreme value theory to analyze and compare the incremental throughput performance of the unicast, traditional multicast and multi description multicast transmission public data services under the cognitive wireless network scenario. The simulation results show that the incremental analysis results are very accurate even if the number of users is not very large. Both analysis and simulation results show that multi description coding multicast has great advantages over mono and traditional multicast in cognitive scene. Therefore, it is of great significance to use multi description coding multicast in cognitive wireless network to transmit public data. It further validates the importance of this research work and the design resources. The matching algorithm provides theoretical guidance.
Second, in the fourth chapter, a multi description coding multicast scheme based on statistical channel state information is designed. In the previous ideal model, it is assumed that the secondary base station always knows the exact information of all channels in the execution of resource allocation, but the imperfect factors such as channel estimation error, feedback delay, quantization error and so on will restrict the performance of the system. In addition, when the number of multicast users is more, it is unrealistic to carry out frequent channel information feedback. In this paper, based on the characteristics of cognitive wireless networks, this paper studies the allocation of coded multicast resources under non ideal channels, and uses probability statistics, random process, order statistics theory to deduce the theory, and designs a secondary base station with only statistical channel state. A multi description coding multicast scheme for information is presented. The proposed scheme can approach the optimal performance with low complexity and has good practical value.
Third, this paper designs a multi cell coding and multicast resource allocation scheme in the fifth and sixth chapters. Because of the actual system, a cell is not isolated in isolation, multi cell coexistence is the networking mode of the current mainstream cellular system. Therefore, it is necessary to study multicast resource allocation in multi cell scenes. For OFDM based cognitive wireless networks, Multi cell scene needs to consider the same frequency interference between communities, which is more complex than single cell scene. At present, the published literature rarely involves multi cell multicast resource allocation. Firstly, the theoretical performance of multi cell coding multicast is analyzed, and then the theory and method of game theory, how to plan and dual decomposition are used for reference. In this particular scenario, two low complexity distributed algorithms are proposed, which not only avoid the high computing complexity of the centralized resource allocation, but also reduce the feedback overhead between the communities, and achieve a good compromise between the performance and the complexity.
【學(xué)位授予單位】：北京郵電大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TN929.5

【參考文獻(xiàn)】

相關(guān)期刊論文 前3條

1 許文俊;牛凱;賀志強(qiáng);林家儒;吳偉陵;;多播OFDM系統(tǒng)中比例公平資源分配[J];北京郵電大學(xué)學(xué)報;2009年06期

2 許文俊;賀志強(qiáng);牛凱;林家儒;吳偉陵;;OFDM系統(tǒng)中考慮信源編碼特性的多播資源分配方案[J];通信學(xué)報;2010年08期

3 ;Multicast resource allocation with min-rate requirements in OFDM systems[J];The Journal of China Universities of Posts and Telecommunications;2010年03期

，

本文編號：1969726