共查询到19条相似文献,搜索用时 62 毫秒
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给出了IEEE 802.16 PMP支持QoS的带宽调度算法,此算法由BS scheduler和SS scheduler共同实现,带宽的分配单位是时隙,并在NS-2上实现了该算法。通过建立仿真环境,对各种数据流的端到端的延时进行比较,结果表明算法的有效性。 相似文献
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基于IEEE 802.16协议,研究宽带无线接入网中保障QoS的有效带宽资源分配和调度问题。首先,在PMP模式下设计一个有效率的QoS调度算法,利用参数的调整提供更具有弹性的服务质量,以利于rtPS服务支持多媒体传输;然后利用标准中所提供的QoS参数调度各种不同类型的服务业务,分配上传带宽,进而达到有效地使用网络资源。仿真实验结果表明,本方案能够在保证QoS需求的同时,有效地分配带宽资源。 相似文献
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IEEE 802.16支持多种不同类型的调度服务,并将服务质量支持机制引入媒体接入控制层,却没有规定相应的调度算法。在IEEE 802.16定义的mesh模式下,针对不同类型服务,提出了一种区分服务的调度方案,该方案采用集中式和分布式混合调度。仿真结果表明:该方案下系统平均时延和用户满意度均有所改善。 相似文献
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无线城域网标准IEEE 802.16e规定了系统的服务质量(QoS)框架,并把所有服务划分为五种类型,但没有规定具体的QoS调度算法。提出了在不同的业务类型间进行资源调度的算法,并把所有的业务流划分为领先、同步、滞后三种状态,根据业务流的类型以及其所处的状态,采取两级额外带宽再分配策略和补偿机制。仿真结果显示使用该算法提高了系统的资源利用率,同时公平性也得到很好的保障。 相似文献
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通过对IEEE 802.16的QoS机制的分析,针对在802.16中没有详细规定准入控制算法的情况,并结合协议中行定义的业务类型的QoS特性和对移动性的支持,提出一种基于802.16的动态带宽分配准入控制机制.仿真结果表明提出的准入控制机制同带宽预留的固定带宽分配机制相比,系统的切换连接掉线率(CDP)、新增连接的阻塞率(CBP)和带宽利用率均有了明显的改善. 相似文献
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针对接入段多业务非均匀突发性特点,提出了一种实用的全带宽动态分配方案,该方案允许单业务最大可用带宽超出其公平共享范围。分析和实践结果表明,在保证带宽利用率、公平性和满足用户QoS指标的同时,该方案可使有需求链路在系统处于非饱和状态时占用全部剩余带宽(直至全带宽),大大提高系统的总带宽利用率。 相似文献
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Relaying is regarded as a promising technique for enhancing the system throughput and coverage of emerging broadband wireless access networks. While next generation broadband wireless standardization bodies (e.g., LTE-advanced and IEEE 802.16j) have specified the support of relays in general terms, the problem of allocating network resources in an efficient and effective manner remains a challenging issue. In this study, the utility-based resource scheduling optimization problem for IEEE 802.16j transparent relay networks is formulated mathematically and proven to be NP-hard. Two efficient heuristic algorithms, namely Relay Resource Scheduling (RRS) and Adaptive Relay Resource Scheduling (ARRS), are proposed to resolve the resource scheduling problem. RRS maximizes the system utility in networks containing direct and relay mobile stations by exploiting the benefits of optional transmissions. ARRS enhances upon the performance of RRS by adaptively determining the split ratio between the access zone and the transparent zone in the downlink subframe. The computational complexities of both algorithms are shown to be polynomial and proportional to the number of links and subchannels in the network. The simulation results show that the proposed algorithms achieve significantly better throughput and fairness performance than existing schemes such as Partial Proportional Fairness (PPF) and GenArgMAX. 相似文献
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The IEEE 802.16j standard defines both transparent and non-transparent relay transmission mode. The present study formulates and optimizes the relay resource scheduling problem for the case of a non-transparent relay network. It is shown that the resource scheduling problem is NP-Complete. A method is proposed for optimizing the position of the zone boundary adaptively during the resource scheduling process in order to maximize the system throughput. In addition, a low time complexity algorithm designated as MRRS (multi-hop relay resource scheduling) is proposed to obtain an approximate solution for the NP-Complete scheduling problem. In the proposed algorithm, the zone boundary is adjusted adaptively in accordance with the user distribution and the channel state information in such a way as to improve the utilization of the available slots. The simulation results show that MRRS achieves a higher throughput than existing relay resource scheduling algorithms (GenArgMax and Eliminate-Repeat) with no significant loss in fairness. In addition, it is shown that the performance improvement provided by MRRS increases as the hop-count is increased. 相似文献
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802.16是新一代宽带无线接入的标准。标准中明确定义了在MAC层实现QoS的机制,例如:MAC层的通信是基于连接的;将上层业务流根据QoS的要求进行分类等。但是标准对上行带宽的分配机制却未加以定义。我们就这个问题进行了研究,并提出了一种有效的上行带宽分配机制。 相似文献
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分别给出了IEEE 802.16系统中四类服务的流模型,推导出阻塞概率和带宽的关系。基于分析结果,提出了802.16 WMAN的一种带宽分配的机制,并通过仿真将这种阻塞概率上限算法和只能应用于语音流的Erlang B公式作了比较。结果证明,阻塞概率上限算法可以用来近似计算大型网络中的阻塞概率,且在数值计算上比Erlang B公式更具高效性。 相似文献
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依据实时系统中的周期任务模型,研究了一种带宽分配算法实现合理的带宽分配,以保证各节点的消息均能实时传输,并用粒子群算法对其进行了实现。 相似文献
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无线Mesh网络是一种多跳分布式自组织网络。提出了一种IEEE 802.16 Mesh模式下的分布式QoS保障调度算法。该算法充分利用方向性天线带来的空分复用增益,并采用DiffServ机制保证QoS需求。仿真结果表明,所提算法不仅提高吞吐量,而且能够为不同类型的服务提供QoS保障。 相似文献
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《Expert systems with applications》2014,41(16):7621-7629
WiMAX is a futuristic technology which provides simultaneous support for web, video, and voice applications. WiMAX networks are best suitable to real time traffic however the quantity of non real time and best effort traffic cannot be neglected. Distribution of resources in such heterogeneous applications is therefore a challenging task. There are many schedulers available for WiMAX but adaptive and adequate schedulers are still in growing stage of development. This paper introduces a novel method using which a system is developed based on concepts of fuzzy logic to schedule traffic in WiMAX networks. The proposed fuzzy expert system simplifies fair allocation of resources to real as well as non real time traffic. The implementation is based on changing the weights of the queues serving real and non- real time traffic adaptively. New weights will be calculated for each bandwidth request made to base station and these weights will in turn decide amount of bandwidth allocated to different traffic classes. The weights are calculated based on three parameters that are amount of real time and non real time traffic in queues, change in throughput requirement for non real time flows and latency requirement of real time input data. Results obtained by virtue of simulations justify the significance of the proposed method. 相似文献
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The proportional fairness scheduling algorithm on multi-classes 总被引:1,自引:0,他引:1
In this paper, we study resource management models and algorithms that satisfy multiple performance objects simultaneously. We realize the proportional fairness principle based QoS model, which defines both delay and loss rate requirements of a class, to include fairness, which is important for the integration of multiple service classes. The resulting Proportional Fairness Scheduling model formalizes the goals of the network performance, user's QoS requirement and system fairness and exposes the fundamental tradeoffs between these goals. In particular, it is difficult to simultaneously provide these objects. We propose a novel scheduling algorithm called Proportional Fairness Scheduling (PFS) that approximates the model closely and efficiently. We have implemented the PFS scheduling in Linux. By performing simulation and measurement experiments, we evaluate the delay and loss rate proportional fairness of PFS, and determine the computation overhead. 相似文献
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The IEEE 802.16 is a standard for fixed and mobile Broadband Wireless Access (BWA). In this paper, we deal with two key challenges of 802.16-based networks. First, terminals close to cell edge experience poor channel quality, due to severe path-loss and high interference from concurrent transmissions in nearby cells. To address this issue, we propose a framework based on a static partitioning of bandwidth into chunks with different transmission power levels. Terminals with impaired channel conditions can then benefit from being allocated a higher amount of transmission power than the others. Secondly, transmissions should be scheduled according to Quality of Service (QoS) requirements to keep users with real-time video or voice calls satisfied, while best-effort connections should fairly share the remaining capacity. To this aim, we propose a scheduling algorithm, called Power-aware Opportunistic Downlink Scheduling (PODS), that aims at meeting both the QoS and fairness requirements, while taking into account the different power levels of the bandwidth chunks. The performance of the proposed scheduler is assessed through detailed packet-level simulation in realistic scenarios and compared with well-known scheduling algorithms. Results confirm that PODS is able to exploit power boosting to provide real-time connections with the desired level of QoS, irrespectively of their MSs’ channel quality. 相似文献