發(fā)布時(shí)間：2018-10-20 09:24

【摘要】：摘要：移動(dòng)通信技術(shù)經(jīng)歷了第一代頻分多址通信、第二代時(shí)分復(fù)用通信、第三代碼分多址通信,現(xiàn)在已經(jīng)步入到第四代LTE (Long Term Evolution)移動(dòng)通信時(shí)代。移動(dòng)通信給人們的生活帶來(lái)了巨大便利,但同時(shí)也面臨著用戶量激增系統(tǒng)容量有限、基站負(fù)荷過(guò)重、無(wú)線電頻譜資源日益稀缺等問(wèn)題。隨著各種移動(dòng)應(yīng)用的增加,移動(dòng)終端的耗電量也在逐步增大。正是在這種情形下,D2D (Device-to-Device)通信應(yīng)運(yùn)而生。D2D通信是一種設(shè)備到設(shè)備的短距離直通技術(shù),用戶之間傳輸數(shù)據(jù)信息不再通過(guò)基站中轉(zhuǎn)而直接進(jìn)行通信,減輕了基站的負(fù)荷,降低了終端的發(fā)射功率,增加了頻譜利用率。D2D通信雖然有許多優(yōu)點(diǎn),但也存在著遠(yuǎn)近效應(yīng)問(wèn)題影響了D2D通信的質(zhì)量。 本文針對(duì)D2D通信模式下遠(yuǎn)近效應(yīng)現(xiàn)象進(jìn)行研究,分析影響遠(yuǎn)近效應(yīng)的因素以及在不同影響因素作用下的仿真情況。由于D2D通信技術(shù)屬于LTE通信系統(tǒng)范疇,首先介紹了LTE通信的需求、技術(shù)特點(diǎn)、協(xié)議架構(gòu)以及使用到的先進(jìn)技術(shù)等相關(guān)知識(shí)。接著重點(diǎn)介紹了D2D通信的架構(gòu)、建立流程以及和蜂窩通信之間的干擾等。由于CDMA (Code Division Multiple Access)系統(tǒng)多址干擾的存在,遠(yuǎn)近效應(yīng)現(xiàn)象嚴(yán)重影響了CDMA系統(tǒng)的性能,對(duì)LTE系統(tǒng)D2D通信模式也將產(chǎn)生不可忽略的影響。LTE系統(tǒng)采用的是正交頻分復(fù)用OFDM (Orthogonal Frequency Division Multiplexing)多載波調(diào)制方式。由于D2D通信是基于LTE功能流程上的,遠(yuǎn)近效應(yīng)現(xiàn)象在D2D通信模式中產(chǎn)生的情形就會(huì)有所不同。目前抑制遠(yuǎn)近效應(yīng)的方法有功率控制、多用戶檢測(cè)、自適應(yīng)干擾消除以及跳頻等。本文在介紹無(wú)線電波傳播模型和無(wú)線信道模型基礎(chǔ)上,選取城市微小區(qū)(Urban Micro)信道模型作為仿真信道模型,并搭建了基于D2D通信的仿真系統(tǒng)。通過(guò)在不同接收功率、不同時(shí)間偏移量、不同頻率偏移量、不同資源塊間隔等條件下對(duì)D2D遠(yuǎn)近效應(yīng)進(jìn)行了仿真分析并給出了結(jié)論。文章最后將K-means聚類算法應(yīng)用到D2D通信遠(yuǎn)近效應(yīng)場(chǎng)景中進(jìn)行研究,根據(jù)不同的聚類數(shù)以及每個(gè)聚類中不同的同時(shí)發(fā)送信號(hào)的用戶數(shù)進(jìn)行仿真分析并得出結(jié)論。
[Abstract]:Absrtact: the mobile communication technology has experienced the first generation frequency division multiple access communication, the second generation time division multiplexing communication, the third generation code division multiple access communication, now has entered the fourth generation LTE (Long Term Evolution) mobile communication era. Mobile communication brings great convenience to people's life, but it also faces some problems such as the limited capacity of the user surge system, the overload of the base station, the increasingly scarce radio spectrum resources, and so on. With the increase of various mobile applications, the power consumption of mobile terminals is gradually increasing. It is in this situation that D2D (Device-to-Device) communication emerges as the times require. D2D communication is a kind of short-distance direct communication technology from equipment to equipment. The data information transmitted between users is no longer communicated directly through the base station, which reduces the load of the base station. The transmission power of the terminal is reduced and the spectrum efficiency is increased. Although D2D communication has many advantages, it also has the problem of near-far effect which affects the quality of D2D communication. In this paper, the near-far effect in D2D communication mode is studied, and the factors that affect the near-far effect and the simulation under different influence factors are analyzed. As D2D communication technology belongs to LTE communication system, this paper first introduces the requirements, technical characteristics, protocol architecture and advanced technologies used in LTE communication. Then, the architecture of D2D communication, the flow of establishment and the interference between D2D communication and cellular communication are introduced. Due to the existence of multiple access interference (mai) in CDMA (Code Division Multiple Access) system, the near-far effect seriously affects the performance of CDMA system. The D2D communication mode of LTE system will also be affected. The LTE system adopts orthogonal frequency division multiplexing (OFDDM) OFDM (Orthogonal Frequency Division Multiplexing) multicarrier modulation. Because D2D communication is based on LTE function flow, the phenomenon of near-far effect will be different in D2D communication mode. At present, power control, multi-user detection, adaptive interference cancellation and frequency hopping are used to suppress the near-far effect. Based on the introduction of radio wave propagation model and wireless channel model, this paper selects the (Urban Micro) channel model of urban microcell as the simulation channel model, and builds a simulation system based on D2D communication. The D2D far and near effect is simulated and analyzed under different receiving power, different time offset, different frequency offset and different resource block spacing, and the conclusion is given. Finally, the K-means clustering algorithm is applied to the D2D communication near and far effect scene. The simulation analysis is carried out according to the different clustering number and the number of users who send different signals at the same time in each cluster, and the conclusion is drawn.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TN929.5

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