【摘要】：在無線通信技術日益蓬勃的今天,出現(xiàn)了無線局域網(WLAN)、WIMAX、Ad hoc、無線傳感網(WSN)、3G和4G等許多新型的網絡。它們采用不同的組網技術,每種網絡都具有各自的特點和使用范圍,單一的哪一種網絡都不能獨立承擔所有業(yè)務的發(fā)展需要。未來,異構網絡的融合是必然的,每一種網絡的發(fā)展互補共存,融合各種網絡優(yōu)勢,才能為大家提供更優(yōu)質更全面的服務。 WLAN是一種無線局域網技術,局域熱點覆蓋,所能提供的傳輸速率是54Mbps,它主要提供語音業(yè)務；WIMAX是帶寬無線接入技術,覆蓋范圍更廣,數(shù)據傳輸速率高于3G網絡,但它主要受到移動性的限制,它主要提供終端在中低速移動中的高速率數(shù)據業(yè)務；3G網絡是連續(xù)覆蓋,支持終端的高速移動,并能實現(xiàn)無縫漫游,所以它能提供終端在高速移動中的數(shù)據與語音業(yè)務,此時是中低速速率。 本文主要對三種網絡中的兩兩網絡作了系統(tǒng)的切換研究與分析。首先對WLAN、WIMAX以及UMTS三種網絡從協(xié)議標準、組網結構、關鍵技術等方面做詳細介紹,了解各自的優(yōu)缺點及網絡使用范圍,論證三種網絡組網融合的可行性,為后續(xù)異構網絡切換算法的研究做準備。其次,針對WLAN與WIMAX異構網絡間的切換,結合MIH技術,建立WLAN與WIMAX網絡的MIH模型,給出系統(tǒng)模型與切換算法,通過仿真得到了兩種網絡相互切換時系統(tǒng)的丟包數(shù),并分析了產生這一現(xiàn)象的原因。再次,針對WLAN與UMTS異構網絡間的切換,充分利用兩種網絡的優(yōu)勢,提出一種改進代價函數(shù)的垂直切換算法,利用OPNET仿真軟件搭建網絡融合模型。對于兩種網絡,設置兩種WIFI信號接收強度門限值,從信號接受強度、網絡帶寬、用戶喜好因子三個方面進行考慮,利用一種基于距離矢量與累計信號接收強度的聯(lián)合優(yōu)化判決方法,使異構網絡進行自適應的切換判斷。最后,針對UMTS與WIMAX異構網絡的切換,采用預判決機制的模糊控制算法對系統(tǒng)進行仿真分析。提出的方法能節(jié)省系統(tǒng)開銷,提高切換判決的效率。此外,從系統(tǒng)吞吐量、系統(tǒng)丟包率及時延三個方面對系統(tǒng)進行分析比較,采用這種算法能減少不必要切換的發(fā)生,同時也能該有效避免乒乓效應。
[Abstract]:With the development of wireless communication technology, (WLAN), WIMAX,Ad hoc, wireless sensor networks (WSN), 3G and 4G) have emerged. Each network has its own characteristics and scope of use. No single network can meet the development needs of all services independently. In the future, the integration of heterogeneous networks is inevitable. The development and coexistence of each kind of network, and the integration of various network advantages, can provide us with better quality and more comprehensive services. WLAN is a kind of wireless local area network (WLAN) technology, which can provide 54 Mbps. it mainly provides voice service. WIMAX is a bandwidth wireless access technology, covering a wider range, the data transmission rate is higher than 3G network, but it is mainly limited by mobility, it mainly provides high rate data services in the middle and low speed mobile terminal. 3G network is continuous coverage, supports high-speed mobile terminals, and can achieve seamless roaming, so it can provide data and voice services in high-speed mobile terminals. In this paper, we study and analyze the handoff of pairwise networks in three kinds of networks. Firstly, three kinds of networks, WLAN,WIMAX and UMTS, are introduced in detail from the aspects of protocol standard, network structure, key technology and so on. The advantages and disadvantages of each network and the scope of network usage are understood, and the feasibility of the integration of the three networks is demonstrated. To prepare for the subsequent research of heterogeneous network handoff algorithm. Secondly, aiming at the handoff between WLAN and WIMAX heterogeneous networks, the MIH model of WLAN and WIMAX networks is established by combining MIH technology, and the system model and handoff algorithm are given. The causes of this phenomenon are analyzed. Thirdly, aiming at the handoff between WLAN and UMTS heterogeneous networks, a vertical handoff algorithm with improved cost function is proposed, and the OPNET simulation software is used to build the network fusion model by making full use of the advantages of the two networks. For the two networks, two threshold values of WIFI signal reception intensity are set, which are considered from three aspects: signal acceptance strength, network bandwidth, and user preference factor. A joint optimal decision method based on distance vector and cumulative signal receiving intensity is used to make the heterogeneous network perform adaptive handoff judgment. Finally, aiming at the handoff between UMTS and WIMAX heterogeneous networks, the fuzzy control algorithm based on pre-decision mechanism is used to simulate and analyze the system. The proposed method can save system overhead and improve the efficiency of handoff decision. In addition, the system throughput, packet loss rate and delay are analyzed and compared. The proposed algorithm can reduce unnecessary handoff and avoid ping-pong effect.
【學位授予單位】：寧夏大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN92

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本文編號：2307502