毕业设计（论文）-基于IEEE 802.16 QoS机制的接入控制策略的研究.doc

摘要
随着通信技术的迅猛发展,无线接入技术正呈现宽带化和IP化的趋势。而不久前才成为3G通信标准的IEEE ,以其自身所具有的有竞争力的优势,越来越成为业界关注的焦点。随着各种多媒体业务的不断出现,而这些不同的业务在带宽、延迟等方面的要求也互不相同,对这些不同业务提供具有QoS保证的服务,已经成为了非常重要的具有挑战性的问题。
IEEE ,虽然MAC层对QoS机制的架构,信令交互体系,业务流的分类和管理,带宽的请求分配机制都进行了较为完整的定义,但却把参数映射,流量调节,调度算法,接入控制算法等问题留给了开发者解决。
接入控制是QoS保证的重要机制,它的主要任务就是对一个新的业务连接请求,根据新业务的类型,QoS要求,带宽请求和当前的网络资源状况,判决是否接纳该连接。由于无线通信信道带宽资源的限制,很难同时保证QoS和接纳尽可能多的连接,只好在两者间寻找平衡点。如果网络资源已经无法满足新到达业务的要求,可以通过对已接纳的连接进行降级,释放部分资源以满足尽可能多的业务接入网络,但经降级的业务仍需要保证其最基本的QoS要求。同时对不同类型的业务进行优先级的区分,并采用不同的接入控制策略,充分兼顾不同业务的QoS要求。
,接着分析其协议模型,主要是分析网络架构,物理层和MAC层,再对QoS机制的架构,业务流分类,带宽分配和调度机制进行研究,然后重点研究接入控制机制和算法,并通过Matlab对算法进行仿真和分析。
关键字:IEEE ;物理层;MAC层;QoS;接入控制。
Abstract
With the development munication, the wireless access technology tend to be broad band and IP. And the IEEE which is the standard of 3G, have e the focus of the industry for its advantage. As many kinds of multimedia service appear, and the requirements of these services are different, provide QoS guarantee for the different service have e the important and challenged task.
Although the MAC layer of IEEE have defined the structure of the QoS mechanism、interoperability system of signal、classify and management of the service and the distribution of bandwidth, it leave the parameter mapping、flow adjusting、scheduling arithmetic and access control arithmetic to the developer.
CAC(Call Access Control) is the important mechanism of QoS, its main task is to judging whether accept a new connection requirement, according to the type of the connection、requirement of QoS、requirement of bandwidth and the condition work resource. Because of the restrict of bandwidth resource, it have to find a balance point between assure the QoS requirement and accept more connection. It allow to degrade the level of the connection so as to release some resource to accept more connection, but the basic QoS of the degraded connection must be satisfied. And also set the prior