本文選題：正交頻分復(fù)用 + 認(rèn)知無(wú)線(xiàn)網(wǎng)　； 參考：《西安電子科技大學(xué)》2014年博士論文

【摘要】：隨著新的高速無(wú)線(xiàn)應(yīng)用的不斷涌現(xiàn),現(xiàn)有無(wú)線(xiàn)業(yè)務(wù)的不斷發(fā)展,帶寬的需求量在迅速增加,頻譜資源匱乏問(wèn)題日益嚴(yán)重,然而,美國(guó)聯(lián)邦通信委員會(huì)(FCC)實(shí)測(cè)數(shù)據(jù)表明,頻譜資源匱乏的真實(shí)原因來(lái)源于頻譜利用率低下。為了解決頻譜資源短缺,提高頻譜利用率,認(rèn)知無(wú)線(xiàn)電技術(shù)應(yīng)運(yùn)而生。在認(rèn)知無(wú)線(xiàn)網(wǎng)絡(luò)中,認(rèn)知用戶(hù)在頻譜感知的基礎(chǔ)上,機(jī)會(huì)式地接入授權(quán)用戶(hù)的空閑頻帶進(jìn)行通信,在避免對(duì)授權(quán)用戶(hù)產(chǎn)生有害干擾的同時(shí),應(yīng)用動(dòng)態(tài)資源分配技術(shù),大大提高了頻譜利用率。作為一種多載波調(diào)制技術(shù),正交頻分復(fù)用(OFDM)因其頻譜利用率高、抗多徑能力強(qiáng)等特點(diǎn)而被廣泛應(yīng)用于寬帶無(wú)線(xiàn)通信。OFDM靈活的頻譜成形技術(shù)使得它不需要連續(xù)的頻帶即可進(jìn)行數(shù)據(jù)傳輸,有助于高效利用授權(quán)用戶(hù)的空閑頻譜,這種頻譜不連續(xù)的OFDM調(diào)制技術(shù)稱(chēng)之為非連續(xù)OFDM(NC-OFDM),成為了認(rèn)知無(wú)線(xiàn)網(wǎng)絡(luò)物理層技術(shù)的首選。然而,自O(shè)FDM被提出至今,其固有的峰均比高的問(wèn)題仍未得到完美的解決,同時(shí),在非認(rèn)知OFDM系統(tǒng)中,考慮用戶(hù)公平性的資源分配算法的研究仍顯得不足。在頻譜資源匱乏的今天,認(rèn)知OFDM無(wú)線(xiàn)網(wǎng)絡(luò)的提出,具有重要的意義,然而,要實(shí)現(xiàn)認(rèn)知系統(tǒng)和授權(quán)系統(tǒng)的真正共存,必須有效控制認(rèn)知OFDM系統(tǒng)對(duì)授權(quán)系統(tǒng)的帶外干擾,同時(shí),要實(shí)現(xiàn)頻譜利用率的有效提高,必須研究行之有效的認(rèn)知OFDM系統(tǒng)的動(dòng)態(tài)資源分配算法。針對(duì)非認(rèn)知OFDM系統(tǒng)及認(rèn)知OFDM系統(tǒng)存在的問(wèn)題,本文將從非認(rèn)知OFDM系統(tǒng)的峰均比、認(rèn)知OFDM系統(tǒng)的帶外抑制,以及非認(rèn)知OFDM系統(tǒng)及認(rèn)知OFDM系統(tǒng)的資源分配算法等幾方面進(jìn)行研究,具體的研究工作和創(chuàng)新性成果如下:1.針對(duì)OFDM信號(hào)高峰均比(PAPR)問(wèn)題,提出了一種基于門(mén)限的分段壓擴(kuò)算法,以較小的誤比特率(BER)損失,獲得了有效的峰均比抑制。該算法根據(jù)OFDM信號(hào)幅度的統(tǒng)計(jì)分布,將OFDM信號(hào)分成了三類(lèi):小(幅度)信號(hào)、平均(幅度)信號(hào)和大(幅度)信號(hào),通過(guò)選擇合適的門(mén)限,對(duì)大信號(hào)進(jìn)行壓縮以減小峰值,同時(shí)放大小信號(hào),起到提升平均功率的作用,從而達(dá)到峰均比的降低。在接收端,通過(guò)迭代檢測(cè)算法估計(jì)并消除壓擴(kuò)噪聲,有效減小了分段壓擴(kuò)造成的帶內(nèi)失真,減小了系統(tǒng)的BER性能損失。另外,NC-OFDM信號(hào)頻譜的不連續(xù)性使得其峰均比的統(tǒng)計(jì)特性有別于傳統(tǒng)OFDM信號(hào),文中還研究了NC-OFDM信號(hào)峰均比的統(tǒng)計(jì)分布,為進(jìn)一步研究NC-OFDM信號(hào)峰均比抑制算法提供了幫助。2.針對(duì)多用戶(hù)非認(rèn)知OFDM系統(tǒng)下行鏈路的動(dòng)態(tài)資源分配問(wèn)題,提出了一種考慮用戶(hù)優(yōu)先級(jí)的自適應(yīng)子載波分配算法。首先,以?xún)蓚�(gè)用戶(hù)的子載波分配為例分析了用戶(hù)選擇子載波的先后順序?qū)ο到y(tǒng)容量的影響,在此基礎(chǔ)上,提出了一種新的沖突解決算法。在該算法中,每個(gè)用戶(hù)獨(dú)立地在所有子載波中搜尋最佳信道增益的子載波,當(dāng)出現(xiàn)沖突,即多個(gè)用戶(hù)同時(shí)選擇一個(gè)子載波時(shí),由“平均信道增益”的大小決定用戶(hù)選擇沖突子載波的優(yōu)先級(jí)。文中定義了兩種不同的優(yōu)先級(jí)準(zhǔn)則,一種定義平均信道增益較高的用戶(hù)優(yōu)先級(jí)較高,另一種則定義平均信道增益較低的用戶(hù)優(yōu)先級(jí)較高,相應(yīng)地,給出了兩種不同的沖突解決方案。仿真結(jié)果表明,由平均信道增益較低的用戶(hù)優(yōu)先選擇沖突子載波,系統(tǒng)容量可以近似達(dá)到理論上限值。3.針對(duì)OFDM信號(hào)諧波功率較大的問(wèn)題,在認(rèn)知OFDM無(wú)線(xiàn)網(wǎng)絡(luò)中,提出了一種基于星座擴(kuò)展的帶外抑制(諧波抑制)算法。在傳統(tǒng)的星座擴(kuò)展算法中,由于原始數(shù)據(jù)符號(hào)獨(dú)立地進(jìn)行星座擴(kuò)展,很難實(shí)現(xiàn)對(duì)相鄰擴(kuò)展星座點(diǎn)的控制,一旦相鄰擴(kuò)展星座點(diǎn)出現(xiàn)實(shí)部或者虛部符號(hào)相同的情況,將對(duì)諧波抑制非常不利。與傳統(tǒng)星座擴(kuò)展算法不同的是,該算法的星座擴(kuò)展基于符號(hào)對(duì),而不是單個(gè)符號(hào),在該算法中,首先將相鄰的原始數(shù)據(jù)符號(hào)兩兩組成一組,然后以組為單位來(lái)進(jìn)行星座擴(kuò)展,控制擴(kuò)展星座點(diǎn)反相或者接近反相來(lái)實(shí)現(xiàn)帶外輻射的抑制。在接收端,充分利用了發(fā)射端的星座擴(kuò)展表來(lái)糾正判決過(guò)程中可能出現(xiàn)的錯(cuò)誤,減小了由于星座擴(kuò)展帶來(lái)的BER性能損失,理論和仿真結(jié)果均證明了該算法的有效性。4.針對(duì)認(rèn)知OFDM無(wú)線(xiàn)網(wǎng)絡(luò)的資源分配問(wèn)題,首先,分析了認(rèn)知用戶(hù)因帶外輻射和非理想的感知信息對(duì)授權(quán)用戶(hù)造成的干擾,并在資源分配算法的干擾約束中進(jìn)行了綜合考慮;其次,考慮到授權(quán)用戶(hù)的信道占用在評(píng)價(jià)資源分配算法的重要地位,介紹了確定性和隨機(jī)性?xún)煞N授權(quán)用戶(hù)的信道占用模型,在此基礎(chǔ)上,對(duì)認(rèn)知OFDM無(wú)線(xiàn)網(wǎng)絡(luò)的資源分配問(wèn)題進(jìn)行建模。在本文所研究的認(rèn)知無(wú)線(xiàn)網(wǎng)絡(luò)中,認(rèn)知用戶(hù)分別支持實(shí)時(shí)(RT)業(yè)務(wù)(延遲敏感業(yè)務(wù)),和非實(shí)時(shí)(NRT)業(yè)務(wù)(延遲容忍業(yè)務(wù)),相應(yīng)的認(rèn)知用戶(hù)分別為遲延敏感用戶(hù)(DS-CUs)和遲延容忍用戶(hù)(DT-CUs)。由于延遲容忍用戶(hù)關(guān)心吞吐量的大小,而延遲敏感用戶(hù)則更關(guān)心切換時(shí)延的大小,將所研究的認(rèn)知無(wú)線(xiàn)網(wǎng)絡(luò)資源分配問(wèn)題建模為一個(gè)雙層規(guī)劃問(wèn)題,在該雙層規(guī)劃中,上層優(yōu)化目標(biāo)是在滿(mǎn)足延遲敏感用戶(hù)最小速率需求的基礎(chǔ)上最小化其切換時(shí)延,下層優(yōu)化目標(biāo)是延遲容忍用戶(hù)的吞吐量。由于雙層規(guī)劃問(wèn)題求解的復(fù)雜度較高,我們將該最優(yōu)化問(wèn)題分解為子信道分配和功率增強(qiáng)兩個(gè)問(wèn)題的求解,仿真結(jié)果證明了該算法在所研究場(chǎng)景中的有效性。
[Abstract]:With the continuous emergence of new high-speed wireless applications and the continuous development of the existing wireless services, the demand for bandwidth is increasing rapidly, and the shortage of spectrum resources is becoming more and more serious. However, the actual data from the Federal Communications Commission (FCC) of the United States shows that the real source of the lack of spectrum resources is derived from the low utilization of spectrum. In the cognitive wireless network, cognitive users have access to the free frequency band of authorized users on the basis of spectrum sensing in cognitive wireless networks. In order to avoid harmful interference to authorized users, the cognitive users should use dynamic resource allocation technology to improve the spectrum utilization greatly. As a multi carrier modulation technology, orthogonal frequency division multiplexing (OFDM) is widely used in broadband wireless communication.OFDM flexible spectrum forming technology because of its high spectrum utilization and strong anti multipath ability. It makes it not need continuous frequency band to carry out data transmission, and is helpful to efficiently use the free spectrum of authorized users, this frequency The discontinuous OFDM modulation technology is called discontinuous OFDM (NC-OFDM), which has become the first choice in the physical layer technology of cognitive wireless network. However, since OFDM has been proposed, its inherent peak to average high problem has not been solved perfectly. At the same time, in the non cognitive OFDM system, the research of resource allocation algorithm considering the fairness of the user still appears. In the lack of spectrum resources today, it is of great significance to recognize the OFDM wireless network. However, in order to realize the real coexistence of the cognitive system and the authorization system, it is necessary to effectively control the external interference of the cognitive OFDM system to the authorization system. At the same time, to realize the effective enhancement of the frequency utilization rate of the spectrum, the effective cognitive OFD must be studied. The dynamic resource allocation algorithm of M system, in view of the problems of non cognitive OFDM system and cognitive OFDM system, this paper will study the peak to average ratio of non cognitive OFDM system, out of band suppression of cognitive OFDM system, and the resource allocation algorithm of non cognitive OFDM system and cognitive OFDM system, and the specific research work and innovation will be made. The results are as follows: 1. in view of the peak to average ratio (PAPR) problem of OFDM signal, a threshold based segmented compression expansion algorithm is proposed. The effective peak to mean ratio suppression is obtained with smaller bit error rate (BER) loss. The algorithm divides the OFDM signal into three categories: small (amplitude) signal, average (amplitude) signal and large (amplitude) (amplitude) signal based on the statistical distribution of the amplitude of OFDM signal. ) the signal, by selecting the appropriate threshold to compress the large signal to reduce the peak value, and at the same time, play the role of increasing the average power, and thus achieve the decrease of the peak to average ratio. At the receiving end, the iterative detection algorithm is used to estimate and eliminate the pressure expansion noise, effectively reducing the intra band distortion caused by subsection compression and reducing the BER of the system. In addition, the discontinuity of the NC-OFDM signal spectrum makes the statistical characteristics of the peak to average ratio different from the traditional OFDM signal. The statistical distribution of the peak to average ratio of the NC-OFDM signal is also studied in this paper, which provides the dynamic capital for the further study of the NC-OFDM signal peak mean ratio suppression algorithm for the multiuser and non cognitive OFDM system downlink. An adaptive subcarrier allocation algorithm considering user priority is proposed. First, the effect of the sequence of user selection subcarriers on the system capacity is analyzed with two users' subcarrier allocation. On this basis, a new conflict resolution algorithm is proposed. In this algorithm, each user is independently in the algorithm. All subcarriers search for the best channel gain subcarrier. When there is a conflict, when multiple users select a subcarrier at the same time, the size of the "average channel gain" determines the priority of the user's choice of the conflict subcarrier. Two different priority criteria are defined in this paper, and a user priority with higher average channel gain is defined. The higher, the other is the higher priority of the user with lower average channel gain. Accordingly, two different conflict solutions are given. The simulation results show that the user with lower average channel gain preferred the conflict subcarrier, the system capacity can approximate to the theory upper limit value.3. for the higher harmonic power of the OFDM signal. In the cognitive OFDM wireless network, an extra band suppression (harmonic suppression) algorithm based on the constellation extension is proposed. In the traditional constellation extension algorithm, it is difficult to control the adjacent extension constellations because of the independent constellation expansion of the original data symbols. Once the adjacent extension constellations appear in the real or imaginary parts of the constellation, the same sign is the same. Different from the traditional constellation extension algorithm, the constellation extension of the algorithm is based on the symbol pair rather than the single symbol. In this algorithm, the adjacent original data symbol 22 is first formed, then the group is used to expand the constellation, control the inverse of the extension constellation or close to the inverse. At the receiving end, we make full use of the constellation extension table of the transmitter to correct the possible errors in the decision process and reduce the BER performance loss due to the constellation extension. Both the theoretical and simulation results prove the effectiveness of the algorithm for the allocation of the resources of the cognitive OFDM wireless network, first of all,.4.. First, it analyzes the interference caused by the cognitive users to the authorized users because of the out of band radiation and the non ideal perceptual information, and takes the comprehensive consideration in the interference constraints of the resource allocation algorithm. Secondly, considering the important status of the authorized user's channel occupancy in the evaluation of resource allocation algorithms, two kinds of authorized users are introduced. On this basis, we model the resource allocation problem of cognitive OFDM wireless networks. In this cognitive wireless network, cognitive users support real-time (RT) services (delayed sensitive services), and non real-time (NRT) services (delayed tolerant services), and corresponding cognitive users are delayed sensitive users (DS-CUs), respectively. And delay tolerant users (DT-CUs). Because the delay tolerant users are concerned about the size of the throughput, the delay sensitive users are more concerned with the size of the handover delay. The study of the cognitive wireless network resource allocation problem is modeled as a double layer programming problem. In the two-layer programming, the upper level optimization goal is to satisfy the minimum speed of the delay sensitive user. On the basis of the rate requirement, the switching delay is minimized. The lower layer optimization target is the throughput of the delay tolerant user. Because of the high complexity of the two-layer programming problem, we decompose the optimization problem into two problems of subchannel allocation and power enhancement. The simulation results prove the effectiveness of the algorithm in the research scene.
【學(xué)位授予單位】：西安電子科技大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：TN925

【相似文獻(xiàn)】

相關(guān)期刊論文 前10條

1 陳新永;楊瑞娟;李曉柏;;基于子載波消噪和小波變換的頻譜池信道估計(jì)[J];信號(hào)處理;2012年10期

2 賀寧蓉;呂善偉;;OFDM中子載波分簇技術(shù)的應(yīng)用與研究[J];遙測(cè)遙控;2006年03期

3 陳斌;李有明;郭濤;雷鵬;劉小青;;基于子載波配對(duì)的多用戶(hù)協(xié)作中繼系統(tǒng)資源分配算法[J];電信科學(xué);2014年06期

4 馬路娟;李德識(shí);陳健;;一種適用于水下傳感網(wǎng)的動(dòng)態(tài)子載波選擇算法[J];計(jì)算機(jī)仿真;2013年12期

5 郭磊;朱光喜;;多用戶(hù)MIMO-OFDM自適應(yīng)子載波組分配的優(yōu)化算法[J];華中科技大學(xué)學(xué)報(bào)(自然科學(xué)版);2007年12期

6 薛波;顏彪;楊娟;李鳴;;一種改進(jìn)的MC-CDMA系統(tǒng)ORC技術(shù)[J];無(wú)線(xiàn)電通信技術(shù);2006年02期

7 陳寧;盧長(zhǎng)兵;;用預(yù)留子載波降低OFDM系統(tǒng)峰均比的方法[J];計(jì)算機(jī)仿真;2008年10期

8 林煒鵬;;一種新的降低OFDM峰均比的子載波預(yù)留法[J];韓山師范學(xué)院學(xué)報(bào);2011年03期

9 李慶;胡捍英;;基于子載波加權(quán)的峰均比與帶外輻射聯(lián)合降低方法[J];通信學(xué)報(bào);2012年06期

10 周明宇;李立華;張平;王海峰;陶小峰;;兩跳OFDM-AF接力系統(tǒng)中的子載波配對(duì)技術(shù)[J];北京郵電大學(xué)學(xué)報(bào);2008年01期

相關(guān)會(huì)議論文 前2條

1 張京東;石健;胡貴軍;;光OFDM通信系統(tǒng)中的子載波補(bǔ)償技術(shù)[A];全國(guó)第15次光纖通信暨第16屆集成光學(xué)學(xué)術(shù)會(huì)議論文集[C];2011年

2 姜?jiǎng)P;;基于OFDM高速WLAN序列子載波選擇算法[A];四川省通信學(xué)會(huì)2005年學(xué)術(shù)年會(huì)論文集[C];2005年

相關(guān)博士學(xué)位論文 前5條

1 劉淑華;OFDM及認(rèn)知OFDM系統(tǒng)關(guān)鍵技術(shù)研究[D];西安電子科技大學(xué);2014年

2 任占陽(yáng);OFDM系統(tǒng)動(dòng)態(tài)無(wú)線(xiàn)資源分配研究[D];北京郵電大學(xué);2013年

3 王道斌;光正交頻分復(fù)用系統(tǒng)的非線(xiàn)性損傷補(bǔ)償及性能評(píng)估關(guān)鍵技術(shù)研究[D];北京郵電大學(xué);2012年

4 張陽(yáng);無(wú)線(xiàn)通信系統(tǒng)中的關(guān)鍵傳輸技術(shù)研究[D];西安電子科技大學(xué);2011年

5 余官定;多載波與合作通信系統(tǒng)中的資源優(yōu)化分配研究[D];浙江大學(xué);2006年

相關(guān)碩士學(xué)位論文 前10條

1 曹久良;OFDM調(diào)制系統(tǒng)峰均比抑制算法及FPGA實(shí)現(xiàn)[D];西安電子科技大學(xué);2014年

2 劉芳;基于預(yù)留子載波的OFDM系統(tǒng)峰均比抑制算法研究[D];西安電子科技大學(xué);2014年

3 李靜;基于博弈論和免疫克隆算法的認(rèn)知無(wú)線(xiàn)網(wǎng)絡(luò)資源的優(yōu)化分配[D];西安電子科技大學(xué);2014年

4 王宇飛;MIMO-OFDM系統(tǒng)天線(xiàn)和子載波聯(lián)合分配問(wèn)題研究[D];哈爾濱工程大學(xué);2010年

5 聶凌峰;基于子載波保留法降低OFDM系統(tǒng)峰均比的研究[D];西南交通大學(xué);2010年

6 李多一;基于子載波分組多用戶(hù)OFDM資源分配算法[D];南京大學(xué);2014年

7 張健;預(yù)留子載波法降低OFDM系統(tǒng)峰均比的研究[D];哈爾濱工程大學(xué);2011年

8 呂征南;多用戶(hù)OFDM系統(tǒng)的自適應(yīng)子載波和比特分配算法[D];吉林大學(xué);2006年

9 肖力勇;OFDM系統(tǒng)中ICI分析及其消除方法研究[D];哈爾濱工程大學(xué);2012年

10 張軍;MIMO-OFDM系統(tǒng)的子載波智能分配及小區(qū)間干擾抑制[D];上海師范大學(xué);2010年

，

本文編號(hào)：2014776