3G、WLAN和WIMAX无线异构网络的切换问题研究

发布时间：2018-11-03 10:19

【摘要】：在无线通信技术日益蓬勃的今天,出现了无线局域网(WLAN)、WIMAX、Ad hoc、无线传感网(WSN)、3G和4G等许多新型的网络。它们采用不同的组网技术,每种网络都具有各自的特点和使用范围,单一的哪一种网络都不能独立承担所有业务的发展需要。未来,异构网络的融合是必然的,每一种网络的发展互补共存,融合各种网络优势,才能为大家提供更优质更全面的服务。 WLAN是一种无线局域网技术,局域热点覆盖,所能提供的传输速率是54Mbps,它主要提供语音业务；WIMAX是带宽无线接入技术,覆盖范围更广,数据传输速率高于3G网络,但它主要受到移动性的限制,它主要提供终端在中低速移动中的高速率数据业务；3G网络是连续覆盖,支持终端的高速移动,并能实现无缝漫游,所以它能提供终端在高速移动中的数据与语音业务,此时是中低速速率。本文主要对三种网络中的两两网络作了系统的切换研究与分析。首先对WLAN、WIMAX以及UMTS三种网络从协议标准、组网结构、关键技术等方面做详细介绍,了解各自的优缺点及网络使用范围,论证三种网络组网融合的可行性,为后续异构网络切换算法的研究做准备。其次,针对WLAN与WIMAX异构网络间的切换,结合MIH技术,建立WLAN与WIMAX网络的MIH模型,给出系统模型与切换算法,通过仿真得到了两种网络相互切换时系统的丢包数,并分析了产生这一现象的原因。再次,针对WLAN与UMTS异构网络间的切换,充分利用两种网络的优势,提出一种改进代价函数的垂直切换算法,利用OPNET仿真软件搭建网络融合模型。对于两种网络,设置两种WIFI信号接收强度门限值,从信号接受强度、网络带宽、用户喜好因子三个方面进行考虑,利用一种基于距离矢量与累计信号接收强度的联合优化判决方法,使异构网络进行自适应的切换判断。最后,针对UMTS与WIMAX异构网络的切换,采用预判决机制的模糊控制算法对系统进行仿真分析。提出的方法能节省系统开销,提高切换判决的效率。此外,从系统吞吐量、系统丢包率及时延三个方面对系统进行分析比较,采用这种算法能减少不必要切换的发生,同时也能该有效避免乒乓效应。
[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.
【学位授予单位】：宁夏大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN92

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