本文選題：協(xié)作MIMO + 緩存控制　； 參考：《南京郵電大學(xué)》2017年碩士論文

【摘要】：隨著科學(xué)技術(shù)的發(fā)展,在線視頻播放應(yīng)用對(duì)無(wú)線系統(tǒng)的性能要求越來(lái)越高。移動(dòng)用戶對(duì)視頻數(shù)據(jù)的傳輸速率和視頻播放的質(zhì)量也提出了更高的要求。同時(shí),用戶終端視頻播放將會(huì)產(chǎn)生大量的流量消耗,大量的網(wǎng)絡(luò)流量給核心網(wǎng)和接入網(wǎng)帶來(lái)了巨大的帶寬壓力。為了緩解網(wǎng)絡(luò)容量需求爆炸式的增長(zhǎng),可緩存的機(jī)會(huì)性協(xié)作MIMO框架應(yīng)運(yùn)而生。它可以改變無(wú)線網(wǎng)絡(luò)的拓?fù)浣Y(jié)構(gòu),有效減小用戶反復(fù)請(qǐng)求熱門(mén)資源所產(chǎn)生的帶寬消耗。從而減輕網(wǎng)絡(luò)負(fù)擔(dān)提高用戶的服務(wù)質(zhì)量。本文研究了一種可緩存的機(jī)會(huì)性協(xié)作MIMO框架。通過(guò)在中繼配備緩存并將一部分視頻文件預(yù)先存放在緩存中,然后利用協(xié)作MIMO將視頻文件傳輸給用戶,這樣可以有效節(jié)省系統(tǒng)帶寬。首先在兩個(gè)時(shí)間尺度上討論了系統(tǒng)花費(fèi),并將問(wèn)題分解成短期的功率控制和長(zhǎng)期的緩存控制兩個(gè)子問(wèn)題。然后研究了一個(gè)容許的功率控制策略,并利用近似貝爾曼方程求解功率控制問(wèn)題,證明了在相同的發(fā)射功率下該控制策略可以提供更好的視頻播放性能。接下來(lái)推導(dǎo)出緩存優(yōu)化問(wèn)題的近似表達(dá)式,并研究了如何用隨機(jī)次梯度算法求解這個(gè)優(yōu)化問(wèn)題,同時(shí)提出了遺傳算法進(jìn)行緩存優(yōu)化。然后,對(duì)用戶終端緩沖區(qū)緩沖數(shù)據(jù)的隊(duì)列動(dòng)態(tài)和視頻播放性能指標(biāo)進(jìn)行分析。用隊(duì)列縮放的方法求得各個(gè)性能指標(biāo)的封閉形式表達(dá)式。對(duì)比了在最大距離可分碼緩存策略和普通緩存策略下的視頻播放性能。并研究了注水法和部分信道倒置法緩存控制策略對(duì)平均發(fā)射功率,緩存溢出概率的影響。最后通過(guò)仿真對(duì)比了遺傳算法和隨機(jī)次梯度算法對(duì)系統(tǒng)花費(fèi)的影響;并仿真分析了不同緩沖區(qū)閾值對(duì)緩存頻率和緩存延遲的影響。
[Abstract]:With the development of science and technology, the performance of wireless system is required more and more. Mobile users also put forward higher requirements for the transmission rate of video data and the quality of video playback. At the same time, the user terminal video playback will produce a large amount of traffic consumption, a large number of network traffic to the core network and access network brings huge bandwidth pressure. In order to alleviate the explosive growth of network capacity, a caching opportunistic cooperative MIMO framework emerges as the times require. It can change the topology of wireless network and reduce the bandwidth consumption caused by users repeatedly requesting hot resources. Thus lighten the network burden and improve the service quality of users. In this paper, a caching opportunistic cooperative MIMO framework is studied. By providing buffer in relay and storing some video files in cache, and then transferring video files to users by cooperative MIMO, the system bandwidth can be saved effectively. First, the system cost is discussed on two time scales, and the problem is decomposed into two sub-problems: short-term power control and long-term buffer control. Then an allowable power control strategy is studied and the approximate Berman equation is used to solve the power control problem. It is proved that the control strategy can provide better video playback performance under the same transmit power. Then the approximate expression of the buffer optimization problem is derived, and how to solve the optimization problem by the stochastic subgradient algorithm is studied. At the same time, a genetic algorithm is proposed to optimize the cache. Then, the queue dynamics and video playback performance of buffer data in user terminal are analyzed. The closed form expression of each performance index is obtained by queue scaling method. The video playback performance under the maximum distance divisible code cache strategy and the common cache strategy is compared. The effect of buffer control strategy of water injection and partial channel inversion on average transmit power and buffer overflow probability is studied. Finally, the effects of genetic algorithm and stochastic sub-gradient algorithm on system cost are compared, and the effects of different buffer thresholds on buffer frequency and buffer delay are analyzed.
【學(xué)位授予單位】：南京郵電大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TN919.3

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本文編號(hào)：2097846