【摘要】：由于Ad hoc網(wǎng)絡(luò)的組網(wǎng)靈活性強、支持移動性、易于迅速展開、系統(tǒng)整體抗毀能力強和系統(tǒng)成本低等特點,被廣泛應(yīng)用于車輛聯(lián)網(wǎng)、應(yīng)急救援和軍用戰(zhàn)術(shù)網(wǎng)絡(luò)等網(wǎng)絡(luò)場景中。然而,隨著各種各樣上層業(yè)務(wù)涌現(xiàn),Ad hoc網(wǎng)絡(luò)的容量以及傳輸質(zhì)量亟需提升,全向Ad hoc網(wǎng)絡(luò)已經(jīng)無法得到滿足。因此引入定向天線,利用定向天線在天線增益、傳輸范圍和抗干擾能力的優(yōu)勢,可以極大改善移動Ad hoc網(wǎng)絡(luò)的性能。然而,定向天線為Ad hoc網(wǎng)絡(luò)帶來好處的同時,也引入了諸如 耳聾‖和天線增益不對稱導致的隱藏終端等問題。因此,如何設(shè)計高效定向MAC協(xié)議,使得定向天線的性能和優(yōu)勢得以發(fā)揮的同時又有效地減輕上述問題,是本文研究的重點。首先,論文在NS-3上設(shè)計了波束寬度和數(shù)量可調(diào)的波束切換定向天線模型,實現(xiàn)了經(jīng)典的定向MAC協(xié)議——DVCS協(xié)議,包括對原有WLAN模型進行擴展,提供天線波束的切換、鎖定和解鎖功能,建立到達方向角緩存和定向網(wǎng)絡(luò)分配向量表。結(jié)果驗證,定向天線的使用提高了Ad hoc網(wǎng)絡(luò)的吞吐量、降低了節(jié)點間的干擾,提升了分組遞交率、縮短了分組平均時延。其次,由于多向時序RTS協(xié)議分類中的CRCM協(xié)議無需事先知道節(jié)點位置信息,且通過依次發(fā)送定向RTS和定向CTS包減輕“耳聾”問題和因天線增益不同而導致的隱藏終端問題,論文對CRCM協(xié)議進行適用性分析,仿真結(jié)果表明,CRCM協(xié)議有效減輕定向MAC面臨的問題,與DVCS協(xié)議及全向MAC協(xié)議相比較提高了網(wǎng)絡(luò)吞吐量,對移動場景的適應(yīng)能力更好。最后,針對大量連續(xù)穩(wěn)定的業(yè)務(wù)模型,CRCM協(xié)議存在發(fā)送控制分組時間長而導致的通信效率低的問題,論文提出了一種改進的CRCM協(xié)議,通過合理減少循環(huán)RTS和CTS握手次數(shù),并改進隨機退避算法,提升協(xié)議的傳輸效率。結(jié)果表明所提協(xié)議減少了控制開銷,提升了傳輸效率,提高了吞吐量,降低了分組時延。
[Abstract]:Ad hoc network is widely used in network scenarios such as vehicle networking, emergency rescue and military tactical networks because of its strong flexibility, mobility, ease of rapid deployment, strong overall anti-destruction ability and low system cost. However, with the emergence of various upper layer services, the capacity and transmission quality of, Ad hoc networks need to be improved, omnidirectional Ad hoc networks can not be satisfied. Therefore, the performance of mobile Ad hoc networks can be greatly improved by introducing directional antennas and utilizing the advantages of directional antennas in antenna gain, transmission range and anti-jamming ability. However, while directional antennas bring benefits to Ad hoc networks, problems such as deafness and hidden terminals caused by antenna gain asymmetry are also introduced. Therefore, how to design an efficient directional MAC protocol to give full play to the performance and advantages of directional antennas while effectively reducing the above problems is the focus of this paper. Firstly, the paper designs a beam-switching directional antenna model with adjustable beamwidth and number on NS-3, and implements the classical directional MAC protocol-DVCS protocol, including extending the original WLAN model to provide antenna beam switching. Lock and unlock functions, build DOA cache and directional network assignment scale. The results show that the use of directional antenna can improve the throughput of Ad hoc network, reduce the interference between nodes, improve the packet delivery rate and shorten the average packet delay. Secondly, the CRCM protocol in the classification of multidirectional sequential RTS protocols does not need to know the node location information in advance, and the "deafness" problem and the hidden terminal problem caused by different antenna gain are alleviated by sending the directed RTS and directed CTS packets in turn. The applicability of CRCM protocol is analyzed in this paper. The simulation results show that the CRCM protocol can effectively alleviate the problems faced by directed MAC. Compared with DVCS protocol and omnidirectional MAC protocol, the network throughput is improved and the adaptability to mobile scenes is better. Finally, aiming at a large number of continuous and stable traffic models, the CRCM protocol has the problem of low communication efficiency due to the long time of sending and controlling packets. In this paper, an improved CRCM protocol is proposed, which can reasonably reduce the number of circular RTS and CTS handshake. And improve the random Backoff algorithm to improve the transmission efficiency of the protocol. The results show that the proposed protocol reduces the control overhead, improves the transmission efficiency, improves the throughput and reduces the packet delay.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN929.5

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相關(guān)碩士學位論文 前1條

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本文編號：2343162