支持空间迷你时槽重用的IEEE 802.16Mesh网络多播调度算法

In this paper, we propose a mechanism for multicast data transmission in IEEE 802.16 mesh networks aimed at increasing the throughput by incorporating mini-slot spatial reuse. The proposed mechanism includes two novel algorithms: a source-based multicast tree topology construction algorithm followed by an interference-aware multicast scheduling algorithm. The proposed multicast interfer-ence-aware scheduling algorithm can be ap-plied to both source-based and rendez-vous-based multicast tree topologies. Results of our simulation study show that in compari-son to the mechanism used for the IEEE 802.16’s standard, the proposed multicast tree generation algorithm reduces the number of consumed mini-slots by 64% on average. Moreover, using the proposed interfer-ence-aware scheduling algorithm decreases the number of required mini-slots by a further 22% on average. Therefore, the proposed multicast scheduling mechanism shows a higher throughput than the previous ap-proaches and it is more scalable with respect to increasing the number of multicast groups as well as increasing the number of members inside each multicast group.     

一种IEEE 802.16无线网络的优化带宽调度策略

提出了一种基于预测的自适应实时轮询业务带宽分配机制:SS依据当前带宽需求和以往的实际分配带宽,对实时业务数据包所需求的确切带宽进行预测并调度.给出了数学分析模型和仿真,结果表明,与传统的带宽分配机制相比,该自适应的带宽分配算法能更好地改善系统性能,提高吞吐量,减少时延,减少缓冲区需求.     

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.     

无线Mesh网络跨层设计研究

首先简要介绍无线Mesh网络（WMN）出现的背景、WMN的典型结构等;随后,讨论WMN的跨层设计问题,包括跨层设计的必要性和主要技术障碍;讨论了目前WMN跨层设计中一些关键技术问题。期望文章使读者对WMN的关键技术,特别是跨层设计有一个概括性的了解,为进一步研发WMN奠定基础。     

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.     

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。     

Cross-layer Based Delay-constraint Adaptive Polling for High Density Subscribers in IEEE 802.16 WiMAX Networks

The IEEE 802.16 standard (namely WiMAX) is proposed to support QoS-aware transmission of real-time service in Wireless Metropolitan Area Networks (WMANs). WiMAX also can operate as a wireless backbone, and then cooperates with WiFi to form a heterogeneous wireless network. Thus, hot spots of WiFi belonging to different WiMAX networks can communicate with each other. For achieving that a Base Station (BS) serves a large number of Subscriber Stations (SSs), WiMAX uses a centralized polling access mechanism instead of a random access mechanism. WiMAX thus avoids occurring access collisions but causes long polling delay under a high-density SSs situation. Consequently, IEEE 802.16 does not schedule real-time service (rtPS) while the BS is in multicast polling mode. This problem of long polling delay becomes worse when the BS serves high-density SSs, because the BS only polls some SSs or groups in every frame time. This paper thus proposes an adaptive polling approach with a cross-layer mechanism, which dynamically polls SSs among different polling modes while continuously supporting the rtPS service. The approach consists of two phases. The first phase adopts two hysteresises of number of SSs and residual bandwidth to determine the optimal polling mode for each connection. The second phase presents a novel QoS-aware rtPS service (QrtPS) that provides an Average Delay requirement instead of the Maximum Delay requirement to take over the rtPS service when a SS is polled by the multicast mode. Additionally, a cross-layer mechanism is proposed to achieve that the real-time applications can be sent with a high-quality or low-quality video codec when the SS is in unicast or multicast mode, respectively. Numerical results demonstrate that the proposed approach significantly outperforms IEEE 802.16 in average delay and network utilization. Furthermore, the collision probabilities of using different numbers of contention slots of an uplink subframe and different numbers of groups within a BS are evaluated for the multicast mode. The results meet the experiments.

基于IEEE802.16系列标准的无线城域网

本文主要介绍了无线城域网技术IEEE802.16x系列标准及其协议栈模型,重点讨论了媒体接入控制层和物理层的特点及其关键技术;最后提出了无线城域网技术未来的研究方向.     

Efficient routing and centralized scheduling algorithms for IEEE 802.16 Mesh Networks

An IEEE 802.16 wireless system can provide broadband wireless access to subscriber stations and operate in mesh mode. The communication between a subscriber station and a base station can pass through one or more intermediate subscriber stations. The IEEE 802.16 standard provides a centralized scheduling mechanism that supports contention‐free and resource‐guarantee transmission services in mesh mode. However, the corresponding algorithm to this schedule is quite primitive in the standard. In this paper, we propose a more efficient way to realize this schedule by maximizing channel utilization. Our designs are divided into two phases: routing and scheduling. First, a routing tree topology is constructed from a given mesh topology by our proposed tree construction algorithm. Secondly, we allocate channel resources to the edges in the routing tree by our proposed scheduling algorithm. To further support the quality‐of‐service schedule, we extend our designs by addressing some issues such as service class, admission control and fairness. Simulation results show the superiority of our proposed algorithms over others. Copyright © 2011 John Wiley & Sons, Ltd.     

Centralized Resource Allocation for Multimedia Traffic in IEEE 802.16 Mesh Networks

The IEEE 802.16 standard provides a high degree of flexibility for setting up and operating wireless broadband networks in metropolitan environments. The standard supports numerous capabilities, including mesh topologies and multimedia communications. In this paper, we study these two features by investigating how efficiently an IEEE 802.16 mesh network can treat distributed multimedia traffic by providing differentiated quality of service (QoS). A key component of the system is the ldquoenhanced frame registry tree schedulerrdquo (E-FRTS) that provides QoS-aware resource allocation using a tree structure to prepare the creation of time frames and reduce processing requirements at the beginning of each frame. Simulation results show that distributed multimedia traffic can be efficiently supported in mesh 802.16 networks, provided efficient scheduling and a reasonable number of hops.     

IEEE 802．16中基于信道状态的改进分组调度算法

为适应IEEE802．16无线网路的特点,降低数据的分组超时率,提高数据的平滑性,在基于信道状态的分组调度算法（CSDPS算法）的基础上,提出了一种基于信道状态的改进分组调度算法。该算法把业务区分与信道状态结合起来,既考虑了不同业务的QoS需求,也考虑了无线网络的信道特点。在降低发送速率上,给出降低速率的具体计算公式。通过理论分析,用改进算法与原有CSDPS算法进行了对比。可以发现,改进算法在分组超时率和数据平滑性上都有较大改善。     

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.     

Battery-Aware Scheduling in Wireless Mesh Networks

Wireless mesh networks recently emerge as a flexible, low-cost and multipurpose networking platform with wired infrastructure connected to the Internet. A critical issue in mesh networks is to maintain network activities for a long lifetime with high energy efficiency. As more and more outdoor applications require long-lasting, high energy efficient and continuously-working mesh networks with battery-powered mesh routers, it is important to optimize the performance of mesh networks from a battery-aware point of view. Recent study in battery technology reveals that discharging of a battery is nonlinear. Batteries tend to discharge more energy than needed, and reimburse the over-discharged energy later if they have sufficiently long recovery time. Intuitively, to optimize network performance, a mesh router should recover its battery periodically to prolong the lifetime. In this paper, we introduce a mathematical model on battery discharging duration and lifetime for wireless mesh networks. We also present a battery lifetime optimization scheduling algorithm (BLOS) to maximize the lifetime of battery-powered mesh routers. Based on the BLOS algorithm, we further consider the problem of using battery powered routers to monitor or cover a few hot spots in the network. We refer to this problem as the Spot Covering under BLOS Policy problem (SCBP). We prove that the SCBP problem is NP-hard and give an approximation algorithm called the Spanning Tree Scheduling (STS) to dynamically schedule mesh routers. The key idea of the STS algorithm is to construct a spanning tree according to the BLOS Policy in the mesh network. The time complexity of the STS algorithm is O(r) for a network with r mesh routers. Our simulation results show that the STS algorithm can greatly improve the lifetime, data throughput and energy consumption efficiency of a wireless mesh network.     

TCP-Aware Uplink Scheduling for IEEE 802.16

In IEEE 802.16 networks, a bandwidth request-grant mechanism is used to accommodate various QoS requirements of heterogeneous traffic. However, it may not be effective for TCP flows since (a) there is no strict QoS requirement in TCP traffic; and (b) it is difficult to estimate the amount of required bandwidth due to dynamic changes of the sending rate. In this letter, we propose a new uplink scheduling scheme for best-effort TCP traffic in IEEE 802.16 networks. The proposed scheme does not need any bandwidth request process for allocation. Instead, it estimates the amount of bandwidth required for a flow based on its current sending rate. Through simulation, we show that the proposed scheme is effective to allocate bandwidth for TCP flows     

Spectral Analysis of the Queueing Model for IEEE 802.16 Wireless Networks

Wireless Personal Communications - Worldwide Interoperability for microwave access (WiMAX) based on the IEEE 802.16 standard has become one of the most promising wireless technologies and been...     

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.     

一种用于IEEE 802.16无线城域网TDD模式中的带宽调度方案

该文提出了一种用于IEEE 802.16宽带无线接入系统TDD模式下的公平而有效的带宽分配调度体系。与该领域中传统的固定带宽分配方式相比,该文提出的调度体系结构综合考虑了上下行链路不同业务带宽需求并进行动态带宽分配。该文提出一种新的亏空公平优先级队列(DFPQ)算法来调度不同优先级的业务流,可以为系统提供更好的公平性。仿真结果显示该文提出的调度体系结构能够很好地满足所有类型业务的服务质量(QoS)需求,并提供较好的公平性。     

Application of IEEE 802.16 Mesh Networks as the Backhaul of Multihop Cellular Networks

Cellular networks have been widely used to support many new audio-and video-based multimedia applications. The demand for higher data rate and diverse services has driven the research on multihop cellular networks (MCNs). With its ad hoc network features, an MCN can offer many additional advantages, such as increased network throughput, scalability and coverage. However, providing ad hoc capability to MCNs is challenging as it may require proper wireless interfaces. In this article, the architecture of IEEE 802.16 network interface to provide ad hoc capability for MCNs is investigated, with its focus on the IEEE 802.16 mesh networking and scheduling. Several distributed routing algorithms based on network entry mechanism are studied and compared with a centralized routing algorithm. It is observed from the simulation results that 802.16 mesh networks have limitations on providing sufficient bandwidth for the traffic from the cellular base stations when a cellular network size is relatively large.     

基于无线Mesh网络的多目标TDMA调度算法

无线mesh网络的迅速发展使其得到了广泛的应用,此类网络的研究中,MAC层的资源优化问题备受关注.本文就无线mesh网络MAC层的时槽分配调度问题,提出了基于NSGA-Ⅱ算法的CNSGA-Ⅱ算法.理论分析和仿真结果表明该算法所得到的Pareto解集具有较好的相对覆盖率和整体前沿扩展性能,能在能耗和时延两个目标参数之间达到较好的平衡状态.     

IEEE802.16d Mesh模式及其调度机制分析

随着无线通信技术的发展,基于IEEE802.16协议的WiMAX技术得到了广泛的关注,对于协议相关内容的分析与研究也就显得尤为重要。本文基于IEEE802.16d协议的定义,分析了Mesh网络拓扑结构的特点以及Mesh模式下的帧结构,同时结合标准BS项目的具体实现过程,对于协议定义的Mesh下的调度机制进行了一定分析。