【作者】 董国军；

【导师】 戴居丰；

【作者基本信息】 天津大学 ， 通信与信息系统， 2007， 博士

【摘要】 近年来,随着移动通信的快速发展和无线宽带接入的迫切需要,IEEE 802.16e快速登台亮相。但是,相对其比较成熟的市场环境,IEEE 802.16e标准尚存在诸多技术问题,其中包括MAC层调度和资源管理。MAC层调度和资源管理是服务基站(BS)对可分配传输资源进行有效管理的调度操作,涉及调度服务、动态频率选择、休眠模式和越区切换等操作。IEEE 802.16e标准只定义了MAC层调度和资源管理的功能模块以及各模块的基本内容和实施原则,并没有提出具体的可操作方案或实施算法。因此,对于MAC层调度和资源管理的研究,特别是在提高系统资源利用率和支持终端移动性方面,具有非常重要的现实意义和实用价值。本文首先研究了调度服务算法对可分配传输资源的有效管理。基于PF(Proportional Fairness)调度算法,提出了非实时、实时和综合调度服务优化算法;根据资源分配单元的不同将非实时和综合调度服务算法分别区分为基于OFDM符号(Symbol)和子信道(Subchannel)的算法;通过对实时业务的数学建模,提出了一种调度服务类型:irtPS(优化的实时查询调度)。仿真结果显示,这些优化算法满足了各种调度服务类型的QoS要求,以短时间不公平为代价保证了长时间公平,并在兼顾公平的前提下实现了系统资源利用率的最大化。其次,研究了动态频率选择方案对可分配传输资源容量的影响。提出了一种优化的动态频率选择方案,该方案是对资源分配单元和调度信息传递在子信道域、调制编码域和子载波域的三维选择。仿真结果显示,当IEEE 802.16e OFDM系统工作在非许可频段时,引入该优化方案后,BER性能和系统容量较引入前均有所改善,但BER性能的改善也以牺牲一定的系统容量为代价。再次,研究了移动终端(MS)通过休眠模式来减少其对可分配传输资源的占用。提出了最大化休眠模式能量节省效率的方法,以减少移动终端对空中接口资源的占用,从而提高系统资源的利用率。并对两种休眠模式状态进行了数学建模:单个功率节省类型I和多个功率节省类型组合。数学分析结果显示,基于最佳的休眠模式时间参数设置,可以最大化休眠模式的能量节省效率。最后,研究了越区切换对MAC层调度和资源管理的影响。为了最大化系统资源利用率,提出了基于不同的调度服务类型选择越区切换机制的方案,该方案在满足调度服务延时性能的基础上,最小化越区切换相关的MAC层开销。仿真结果显示,越区切换延时性能的改善是以一定的MAC层开销为代价,在满足调度服务延时性能基础上,可以选择MAC层开销较小的越区切换机制。更多还原

【Abstract】 Recently, with rapid development of mobile communication and urgent requirement of wireless broadband access, IEEE 802.16e comes into existance. But, compared with its mature market, IEEE 802.16e specification has many technical problems, such as MAC Layer Scheduling and Resource Management. The MAC Layer Scheduling and Resource Management refers to operation of serving BS (Base Station) to manage effectively allocable transmission resources, which involves Scheduling Services, Dynamic Frequency Selection, Sleep Mode, Handover etc. IEEE 802.16e specification only defines function modules of MAC Layer Scheduling and Resource Management, as well as the basic content and implementation rules of the function modules, but does not propose specifically the feasible schemes or implementing algorithms. Hence, studies of MAC Layer Scheduling and Resource Management, especially on how to improve utilization efficiency of system resources and how to support mobility of the terminal, have great realistic significance and economical value.This paper firstly investigates Scheduling Service algorithms by which effective management of allocable transmission resources is implemented. It proposes non-real-time, real-time and integrated scheduling service algorithms based on PF (Proportional Fairness) scheduling algorithm; according to different definitions of traffic allocation units, divides non-real-time and integrated scheduling service algorithms respectively into algorithms based on OFDM symbol and those based on subchannel; proposes a real-time scheduling service type, irtPS (Improved Real-Time Polling Scheduling), by mathematically modelling real-time traffic. Simulation results show that the proposed algorithms can satisfy QoS requirements of each scheduling service type, ensure long-time fairness at the expense of short-time fairness, and maximize utilization efficiency of system resources taking fairness into account.Secondly, this paper studies Dynamic Frequency Selection scheme which redefines allocable transmission resources. It proposes an improved Dynamic Frequency Selection scheme, in which traffic allocation unit and scheduling information delivery are selected by subchannel domain, modulation and coding domain, subcarrier domain. Simulation results show that, when IEEE 802.16e OFDM system working at unlicensed bands, the proposed scheme can improve BER performance and system capacity, but the improvement of BER performance is achieved at the expense of sytem capacity. Thirdly, this paper explores how to reduce MS’s (Mobile Subscriber) occupation of allocable transmission resources through sleep mode. It proposes a method by which energy saving efficiency of the sleep mode is maximized, thus MS’soccupation of air-interface resources is reduced, and then utilization efficiency of system resources is increased; models mathetically two sleep mode states, including single Power Saving Class I and several Power Saving Classes coexisting with each other. Mathetical analysises show that energy saving efficiency of the sleep mode is maximized by optimizing time parameter configuration of the sleep mode.Finally, this paper inspects influence of handover on MAC Layer Scheduling and Resource Management. It proposes a scheme that, in order to maximize utilization efficiency of system resources, different handover mechanisms are selected depending on distinct scheduling service types, and this scheme minimizes MAC layer overhead related to handover on prerequisite of guaranteeing delay performance of scheduling services. Simulation results show that delay performance of handover is improved at the expense of more MAC overhead, and the handover mechanism with less MAC overhead can be selected on the basis of guaranteeing delay performance of scheduling services.更多还原