本文選題：認(rèn)知無(wú)線電 + OFDM　； 參考：《南京航空航天大學(xué)》2017年碩士論文

【摘要】：隨著無(wú)線通信技術(shù)的發(fā)展,頻譜資源逐漸匱乏。當(dāng)前靜態(tài)的頻譜資源分配方案已經(jīng)造成了頻譜稀缺和利用率不足的困境。于是,認(rèn)知無(wú)線電(CR)憑借其動(dòng)態(tài)頻譜接入的特性,可以提高頻譜利用率,被認(rèn)為是未來(lái)無(wú)線通信網(wǎng)絡(luò)中富有前景的技術(shù)。正交頻分復(fù)用(OFDM)技術(shù)憑借其靈活地動(dòng)態(tài)分配頻譜,已經(jīng)被廣泛應(yīng)用在CR系統(tǒng)的空間接入上,成為襯于底層的技術(shù)。認(rèn)知無(wú)線電技術(shù)和OFDM技術(shù)的結(jié)合能夠充分發(fā)揮兩者的優(yōu)點(diǎn)。因此,如何動(dòng)態(tài)地分配資源來(lái)獲得較高的CR系統(tǒng)性能成為當(dāng)前熱門(mén)的研究方向之一。本文針對(duì)不同優(yōu)化目標(biāo)建立系統(tǒng)模型,研究了基于OFDM的認(rèn)知無(wú)線電的資源分配算法。本文的主要工作和貢獻(xiàn)如下:1.建立了理想感知條件下基于頻譜效率的CR-OFDM資源分配系統(tǒng)模型,考慮主用戶與次用戶之間相互干擾,以系統(tǒng)容量最大化為優(yōu)化目標(biāo)。為了避免較高的計(jì)算復(fù)雜度,提出一種尋求次優(yōu)解的分步式資源分配算法,包括子載波分配算法以及次優(yōu)的功率分配算法。仿真結(jié)果表明,所提出的算法獲得的系統(tǒng)容量可以逼近最優(yōu)功率分配算法,并且大于傳統(tǒng)功率分配算法,而且其算法復(fù)雜度小,可作為CR-OFDM資源分配中一種次優(yōu)算法。2.建立了非理想感知條件下基于能量效率的CR-OFDM資源分配系統(tǒng)模型,提出一種分步算法,包括子載波分配算法和最優(yōu)的功率分配算法。其中,子載波分配算法以最大化系統(tǒng)能效為基準(zhǔn),在功率分配中采用了分式規(guī)劃理論,再結(jié)合子梯度算法設(shè)計(jì)了功率分配方案。數(shù)值仿真結(jié)果表明,相比于最大容量算法,所提出的資源分配算法可以獲得更高的能量效率,同時(shí),相比于未考慮感知錯(cuò)誤的資源分配方案,此算法可以保證各主用戶間正常通信。3.建立了非理想感知條件下基于中繼協(xié)作的CR-OFDM資源分配系統(tǒng)模型,采用了AF傳輸協(xié)議,以最大化系統(tǒng)的能量效率為目標(biāo),建立了目標(biāo)函數(shù),提出了最優(yōu)的功率分配算法和次優(yōu)的功率分配算法。仿真結(jié)果表明,在考慮了系統(tǒng)不理想的頻譜感知條件下,系統(tǒng)性能不可避免的有些許下降,但是最優(yōu)的功率分配算法仍可以獲得理想的系統(tǒng)能效。相比容量最大化算法,本算法可以提高系統(tǒng)的能量效率。此外,次優(yōu)的功率分配算法也可以在降低計(jì)算復(fù)雜度的同時(shí)取得較好的系統(tǒng)表現(xiàn)。
[Abstract]:With the development of wireless communication technology, spectrum resources are gradually scarce. The current static spectrum resource allocation scheme has caused the difficulty of spectrum scarcity and insufficient utilization. As a result, cognitive radio (CR) can improve spectrum efficiency by virtue of its dynamic spectrum access, and is considered to be a promising technology in future wireless communication networks. Orthogonal Frequency Division Multiplexing (OFDM) technology has been widely used in the space access of CR system because of its flexible and dynamic spectrum allocation. The combination of cognitive radio technology and OFDM technology can give full play to the advantages of both. Therefore, how to dynamically allocate resources to achieve higher CR system performance has become one of the hot research directions. In this paper, the resource allocation algorithm of cognitive radio based on OFDM is studied by establishing the system model for different optimization objectives. The main work and contributions of this paper are as follows: 1. The CR-OFDM resource allocation system model based on spectrum efficiency under ideal perception condition is established. Considering the interference between primary and secondary users, the optimal goal is to maximize the system capacity. In order to avoid high computational complexity, a sub-optimal resource allocation algorithm is proposed, which includes sub-carrier allocation algorithm and sub-optimal power allocation algorithm. Simulation results show that the proposed algorithm can approximate the optimal power allocation algorithm, and is larger than the traditional power allocation algorithm, and its complexity is small, so it can be used as a sub-optimal algorithm in CR-OFDM resource allocation. In this paper, a CR-OFDM resource allocation system model based on energy efficiency under non-ideal perception is established, and a step by step algorithm is proposed, which includes subcarrier allocation algorithm and optimal power allocation algorithm. The sub-carrier allocation algorithm is based on maximizing the energy efficiency of the system. The fractional programming theory is used in the power allocation and the sub-gradient algorithm is used to design the power allocation scheme. The numerical simulation results show that compared with the maximum capacity algorithm, the proposed resource allocation algorithm can achieve higher energy efficiency, at the same time, compared with the resource allocation scheme without perceptual errors, the proposed algorithm can achieve higher energy efficiency. This algorithm can ensure the normal communication between the main users. 3. The model of CR-OFDM resource allocation system based on relay cooperation under non-ideal perception condition is established. AF transport protocol is adopted to maximize the energy efficiency of the system and the objective function is established. The optimal power allocation algorithm and the suboptimal power allocation algorithm are proposed. The simulation results show that the performance of the system will inevitably decrease under the condition that the spectrum sensing is not ideal, but the optimal power allocation algorithm can still achieve the ideal system energy efficiency. Compared with the capacity maximization algorithm, this algorithm can improve the energy efficiency of the system. In addition, the sub-optimal power allocation algorithm can reduce the computational complexity and achieve better system performance.
【學(xué)位授予單位】：南京航空航天大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TN925

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 張冬梅;徐友云;蔡躍明;;OFDMA系統(tǒng)中線性注水功率分配算法[J];電子與信息學(xué)報(bào);2007年06期

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本文編號(hào)：1808773