【作者】 葛音；

【导师】 郭更生；

【作者基本信息】 北京邮电大学 ， 通信与信息系统， 2008， 博士

【摘要】 近年来,宽带无线接入技术迅猛发展,成为通信技术领域新的研究热点。IEEE 802.16e/移动WiMAX网络是下一代宽带无线接入网络的热选方案之一,具有标准化程度高、数据传输速度快、覆盖范围广、扩展能力强、组网灵活等优点,能够为用户提供语音、数据、视频等丰富的多媒体服务。但伴随着业务量的激增,系统资源的有限性与服务需求的无限扩张性之间的矛盾便凸显出来。特别是在恶劣的无线传播环境里以及移动台(MS:mobile station)移动的情况下,如何针对不同业务对服务质量(QoS:quality of service)的不同需求,有效管理和合理配置系统资源,在使资源利用率最大化的同时保证各种业务的QoS,就变得至关重要。本论文就下一代宽带无线接入网络的QoS保证问题,对IEEE 802.16e/移动WiMAX网络中的资源管理策略展开了研究。研究的重点在于点到多点(PMP:point-to-multipoint)网络拓扑结构下的资源预留、接纳控制以及移动终端功率节省等几个方面。本论文的主要工作包括:(1)针对IEEE 802.16e标准中二阶段激活模型(two-phaseactivation model)不适用于实时服务的问题,提出了动态带宽准预留机制(DBQRS:dynamic bandwidth quasi-reservation scheme)和相应的接纳控制策略。基于MS切换概率和MS上业务到达概率的估计对实时服务流进行动态带宽准预留;在接纳控制过程中,非实时服务流可以临时占用准预留带宽。DBQRS机制为移动和固定的实时多媒体服务提供了QoS保证,改善了接纳切换和新发起实时服务流的公平性,提高了带宽利用率。(2)基于IEEE 802.16e系统对自适应多媒体服务的支持,提出了有效的接纳控制机制。根据802.16e标准中定义的数据传递服务类型的特征,为业务设置优先级。切换过程中,如果目标小区的闲置带宽不足时,按优先级从低到高减少激活服务流的带宽,甚至降低切换服务流的带宽请求,以此降低切换服务流掉线率。所有闲置带宽可用于接纳新服务流和切换服务流,有效降低了新服务流阻塞率,系统资源利用率较高。(3)根据IEEE 802.16e系统中功率节省类(PSC:power savingclass)的特点和数据传递服务的性质,提出了一个有效的睡眠模式管理机制。在保证数据传输的情况下,设计了PSC的睡眠窗口和监听窗口,使每个PSC的睡眠窗口尽可能长;提出了“PSC防扩张”概念,在满足业务QoS需求的前提下,使与MS相关联的PSC数目尽可能少。提出的机制使MS的无效间隔最大化,为MS节省更多能量。同时,针对基于PSC的睡眠模式,设计了评估MS能量节省的通用理论分析模型。更多还原

【Abstract】 The increasing demand of accessing broadband Internet conveniently and rapidly has stimulated the development of broadband wireless access (BWA) technologies and made them a new hot topic in communication researches. IEEE 802.16e/mobile WiMAX network, with its various advantages such as perfect standardization, high-speed data transmission, wide service coverage, fast network deployment, easy system scalability, flexible network construction, etc., has become an ideal "last mile" wireless access technology of broadband metropolitan area networks. Mobile WiMAX network supports diversified multimedia services, including data, audio and video. However, this also results in severer conflict between limited resource and huge demand for data transmission in wireless communication system. Requirement for quality of service (QoS) differs among traffics. Under the circumstances of disadvantageous wireless transmission conditions and mobility of mobile station (MS), efficient resource management strategies to meet QoS requirements and maximize resource utilization become crucial. This dissertation addresses the resource management strategies with QoS guarantee in IEEE 802.16e/mobile WiMAX BWA networks. Withpoint-to-multipoint (PMP) network topology, the research focuses on the schemes of resource reservation, admission control and power saving for MS. The main contributions of this dissertation are as follows.1) A dynamic bandwidth quasi-reservation scheme (DBQRS) and the corresponding admission control policy are proposed to address the non-applicability of the two-phase activation model defined in IEEE 802.16e standard to real-time services. Based on the estimations of MS handover probability and the traffic arrival probability, bandwidth is quasi-reserved dynamically for real-time service flows. In the admission control process, non-real-time service flows can occupy the bandwidth quasi-reserved for real-time ones temporarily. DBQRS not only provides QoS guarantee for both mobile and fixed wireless real-time multimedia services in 802.16e networks, but also improves the fairness of admitting new and handover real-time service flows and enhances the bandwidth utilization.2) An efficient admission control scheme is proposed by relying upon IEEE 802.16e system’s ability to support adaptive multimedia services. Traffics are prioritized in accordance with the characteristics of data delivery services defined in 802.16e standard. When the available free bandwidth in the target cell cannot meet the requirement of handover service flow, the bandwidth assigned to active service flows is decreased in ascending order according to the pre-set priorities and even the bandwidth requirement of handover service flow can be reduced, which would decrease handover service flow dropping ratio. All the free bandwidth can be used by either new or handover service flows, thus reducing the new service flow blocking ratio and utilizing the resource more efficiently.3) According to the characteristics of power saving classes (PSCs) and the properties of data delivery services, an efficient sleep mode management scheme is proposed for IEEE 802.16e system. With the precondition of guaranteed data transfer, the PSC parameters, sleep windows and listening windows, are designed. Moreover, the sleep windows of each PSC are maximized. Under the condition that the QoS requirements of traffics are satisfied, the proposed "PSC anti-expansion" mechanism makes the number of PSCs associated with MS as few as possible. The proposed scheme maximizes the unavailability intervals of MS. Consequently, the energy of MS is saved greatly. In addition, a universal theoretical analysis model to assess the saved energy is also designed for PSC-based sleep mode.更多还原