IEEE802.16中一种改进的跨层QoS调度架构设计

IEEE802委员会制定了一个解决“最后一公里”宽带无线城域网（WMAN）接入问题的全球统一标准,即IEEE802．16标准。它定义了支持多种业务类型的独立于具体物理层的MAC层和多个物理层。对于802．16系统的QoS保障,标准中详细规定了服务类别的划分以及系统的Qos框架和具体的信令交互机制,但没有规定具体的QoS调度算法,而是留给厂家设计。因此本文在IEEE802．16已有QoS调度架构的基础上,设计出一种改进的跨层QoS调度架构,并详细介绍了该构架下各功能模块的功能和具体实现方法。     

基于IEEE 802.16e的跨层上行调度架构设计

对IEEE 802.16标准的上行链路调度架构进行了研究,并联合MAC层和物理层,设计了一种跨层的上行调度结构,在满足移动性要求的同时增强了系统的QoS保障能力,使频谱利用率和吞吐量得到提高.     

IEEE 802.16系统的QoS分组调度算法

文章基于IEEE 802.16宽带无线城域网接入标准中定义的QoS架构,对上行分组调度UPS进行了具体的设计,将其分为信息模块、调度数据库模块和服务分配模块三个部分。并且提出了一种基于严格优先级的调度服务原则,为不同类型的服务流提供QoS支持,分别给出了rtPS、nrtPS和BE三种服务的调度算法。文章最后通过具体仿真验证出所提出的策略能够为实时业务提供QoS支持。     

IEEE 802.16中改进的QoS动态分层调度算法设计

WiMAX(IEEE802.16)为每个节点提供实时业务和非实时业务,并对不同的业务提出了QoS保证服务。调度算法是WiMAX为分类业务提供QoS保证的重要技术。本文提出一种用于WiMAX系统PMP模式下的动态调整优先级的分层调度算法DAPQ,DAPQ算法由基站(BS)和用户站(SS)共同实现,为不同优先级的业务流动态分配带宽,可以为系统提供更好的公平性,并有效的减少时延。仿真结果表明,本文提出的算法在一定程度上降低了rtPS业务的时延和丢包率。     

IEEE 802.16 MAC层关键技术研究

IEEE802．16是一种提供电信级QoS保证的宽带无线接入标准，而其QoS的保证主要依赖于其MAC层技术的支撑。文章在概述IEEE802．16MAC层协议的基础上，介绍了处于研究热点的分组调度、跨层设计、冲突避免等MAC层关键技术以及研究现状，最后指出了IEEE802．16MAC层技术的发展趋势。     

IEEE 802.16宽带无线接入系统中基于QoS的调度算法

本文介绍并评估了几种支持IEEE 802.16标准QoS要求的包调度算法,并将它们的重要性能进行了比较.     

基于IEEE802.16e的多级别业务调度算法研究

在IEEE802.16e标准中,保证QoS的调度算法一直是人们研究的热点,它涉及到从单一业务到多级别业务的调度服务.对多级别业务调度的支持是保证系统性能的重要技术之一.本文针对多级别业务常用的分层调度和联合调度策略,从系统吞吐量、QoS性能和公平性等方面对之进行的仿真分析和性能比较.仿真结果表明联合调度策略综合性能较好.     

跨层资源调度算法综述

跨层资源调度对实现资源的有效利用,保证业务的QoS起着重要作用.本文对跨层资源调度的研究状况进行了概述:根据所采用的技术体制和约束类型,介绍了单载波系统和OFDM系统的多用户机会调度问题和相应算法,分析了单一类型和多种类型资源共享约束下的机会调度算法:分别从队列调度、子载波分配和功率控制3个方面,对基于队列和信道状态信息的资源调度算法进行了分析和比较:对提高反馈信息的准确性、减少反馈信息量的方法和机制进行了简要介绍.最后指出了需要进一步研究的问题.     

支持实时多媒体业务QoS醮LTE下行调度研究

日益增长的多媒体业务要求下一代移动通信系统支持具有不同QoS要求的业务。针对LTE下行链路资源分配和调度问题,介绍了支持实时多媒体业务QoS调度算法的最新成果与进展,并对未来研究方向进行了分析展望。     

多用户OFDM系统中基于QoS的跨层资源分配策略

针对多用户OFDM系统的下行链路提出了一种基于QoS的跨层资源分配策略.建立了基于有限长缓存的用户分级模型,推导了有限长缓存引起的用户速率限制条件.根据等待时延将用户分为"高级用户"和"普通用户",在保证所有用户QoS的前提下为"高级用户"优先分配子载波和功率,同时系统的吞吐量达到最大.仿真结果表明,在报文到达率较高的情况下该策略有效降低了系统丢包率,保证了吞吐量.     

Adaptive packet scheduling for the uplink traffic in IEEE 802.16e networks

IEEE 802.16e is a telecommunication standard technology designed to support a wide variety of multimedia applications. It defines five service classes, each one with its respective QoS requirements, but does not define the scheduling algorithm for these service classes. In this paper, an adaptive packet scheduling algorithm for the uplink traffic in IEEE 802.16e networks is proposed. This algorithm is designed to be completely dynamic, mainly in networks that use various modulation and coding schemes (MCSs). The algorithm is applied directly to the bandwidth request queues in the base station (BS) and aims at supporting the real‐time and non‐real‐time applications. Using a cross‐layer approach and the states of the bandwidth request queues in the BS, a new deadlines based scheme was defined, aiming at limiting the maximum delay to the real‐time applications. Moreover, this algorithm interacts with the polling management mechanisms of the BS and controls the periodicity of sending unicast polling to the real‐time and non‐real‐time service connections, in accordance with the QoS requirements of the applications. The proposed algorithm was evaluated by means of modeling and simulation in environments where various MCSs were used and also in environments where only one type of modulation was used. The simulations showed satisfactory results in both environments. Copyright © 2012 John Wiley & Sons, Ltd.     

Adaptive scheduling mechanism for IPTV over WiMAX IEEE 802.16j networks

A WiMAX technology is a very promising Broadband Wireless Access technology that is able to transmit different service types. This latter can have different constraints such as traffic rate, maximum latency, and tolerated jitter. The IEEE 802.16 Medium Access Control specifies five types of QoS classes: UGS, rtPS, ertPS, nrtPS, and BE. However, the IEEE 802.16 standard does not specify the scheduling algorithm to be used. Operators have the choice among many existing scheduling techniques. Also, they can propose their own scheduling algorithms. In this paper, we propose a scheduling strategy (Adaptive Weighted Round Robin, AWRR) for various Internet Protocol Television (IPTV) services traffic over 802.16j networks. Our scheme adapts dynamically the scheduler operation to according queue load and quality of service constraints. In particular, the proposed mechanism gives more priority to high definition television and standard definition television traffic by using two schedulers. The proposed scheduling algorithm has been simulated using the QualNet network simulator. The experimental results show that our scheduler schemes AWRR have a better performance than the traditional scheduling techniques for rtPS traffic, which allows ensuring QoS requirements for IPTV application. Copyright © 2012 John Wiley & Sons, Ltd.     

IEEE802.16中多媒体QoS保证机制的研究

首先分析了IEEE802.16四种业务类型的特点及QoS服务模型,对IEEE802.16的QoS机制和调度策略进行了深入的研究,并对相应的调度算法进行了分析。结果表明,IEEE802.16能够对实时业务提供较好的支持,同时维持其它业务的带宽在可接受的范围之内。     

Design of the QoS framework for the IEEE 802.16 mesh networks

IEEE 802.16 (WiMax) technology is designed to support broadband speeds over wireless networks for the coming era of broadband wireless access (BWA). IEEE 802.16 is expected to provide transmission of high‐rate and high‐volume multimedia data streams for fixed and mobile applications. As an extension of point‐to‐multipoint (PMP) configuration, the IEEE 802.16 mesh mode provides a quicker and more flexible approach for network deployment. Multimedia networking requires quality‐of‐service (QoS) support, which demands elaborate mechanisms in addition to the four service types defined in the specification. By examining standard centralized and distributed scheduling/routing schemes in the mesh mode from QoS aspect, a BS‐controlled and delay‐sensitive scheduling/routing scheme is proposed in the paper. Associate mechanisms including admission control, flow setup and link state monitoring are also proposed. Integration of the proposed mechanisms is presented as a complete QoS framework. Simulation study has demonstrated that the average delay as well as the delay jitters per hop in the proposed scheme is smaller than that of the distributed scheme and much smaller than that of the centralized scheme. Furthermore, proposed mechanisms can also achieve higher throughput than the contrasts and generate much smaller signaling overhead, making the proposed framework a promising scheme for multimedia support in the IEEE 802.16 mesh network. Copyright © 2009 John Wiley & Sons, Ltd.     

A bandwidth allocation algorithm with channel quality and QoS aware for IEEE 802.16 base stations

Subscriber stations located in different places encounter various interferences in an IEEE 802.16 network, resulting in that their communication channels experience varying channel conditions. Thus, an excellent bandwidth allocation algorithm should not only satisfy various QoS required by heterogeneous traffic, but also consider the channel quality to maximize bandwidth utilization. In this paper, a bandwidth allocation algorithm with channel quality awareness and QoS guarantee, called CQQ, is proposed. CQQ not only satisfies each connection's QoS requirement, but also dynamically adjusts the downlink/uplink bandwidth to match current downlink/uplink traffic ratio. CQQ allocates more bandwidth to the connections having better channel quality by applying weighted fair queuing strategy to raise the bandwidth usage. CQQ provides lower delay violation ratio and higher goodput than the previous algorithms, as observed from the simulation results. Copyright © 2012 John Wiley & Sons, Ltd.     

基于IEEE 802.16协议的VoIP服务质量调度算法

本文分析了VoIP的特点和IEEE802．16协议对服务质量（QoS）的定义。基于已有的无线城域网对VoIP的QOS控制策略，提出一种新型的调度算法。通过数学建模和仿真试验，证明了新算法对减小延迟和增加信道利用率方面效果显著。     

802.16宽带无线接入系统的QoS保证和调度策略

IEEE 802.16 (以下简称802.16)宽带无线接入标准最突出的特点就是在其MAC层引入了完整的QoS机制,可以为用户提供电信级的QoS支持,这在宽带无线接入网发展里程中具有重要的意义.本文详细描述了标准MAC层的QoS结构及相关的MAC层机制,并对其QoS机制中的调度策略进行了研究.     

一种基于IEEE802.16无线MESH网络集中调度机制的时隙分配方法

在基于IEEE 802.16的无线Mesht网络中,时隙分配算法对网络性能有重要影响.针对现有时隙分配算法只研究上行链路且时隙分配的结果导致中继节点在转发数据时频繁在相邻时隙间进行收发切换的问题,提出了一种上下行链路通用的时隙分配方法,对于上行链路,跳数较小节点的数据优先传输,而对于下行链路,跳数较大节点的数据优先传输,在传输路径上采用逐跳传输的策略.仿真结果证明了该算法的有效性.