Channel-Aware Scheduling for QoS and Fairness Provisioning in IEEE 802.16/WiMAX Broadband Wireless Access Systems

In the last few years, standardization activities within the IEEE 802.16 Working Group have resulted in the publication of specifications for an air interface of Fixed broadband wireless access systems. WiMAX is the commercial name of products compliant with the approved IEEE 802.16 standard. Although the standard suggests the main principles in designing a QoS architecture to support multimedia broadband services, implementation details are left to manufacturers. This article addresses a channel-aware scheduling algorithm conceived for a point-to-multipoint WiMAX architecture. It aims at enabling downlink traffic delivery with differentiated service treatment, even in nonideal channel conditions. A technique to compensate for channel errors is proposed to preserve QoS and fairness of a WF2Q+ based scheduling algorithm. The performance behavior of the proposed algorithm is confirmed by the outputs of a comprehensive simulation campaign.     

A Bandwidth Efficient Adaptive Call Admission Control Scheme for QoS Provisioning in IEEE 802.16e Mobile Networks

In wireless environment the bandwidth resource is limited and therefore judicious use of the available resources is needed. A bandwidth efficient Call Admission Control (CAC) is proposed in this paper for quality of service (QoS) provisioning for the services defined in IEEE 802.16e mobile WiMAX standards to satisfy both bandwidth and delay guarantees to the admitted connections. The concept of adaptive bandwidth degradation is introduced to improve the bandwidth utilization (BU) of the system. The proposed CAC scheme is analyzed by Markov Chain model and performance evaluation is made in comparison with fixed step size degradation. Results show that the proposed adaptive CAC scheme has excellent BU under stressed network condition. Also the long term average revenue is calculated for different service flows and for the overall system to see the efficiency of the adaptive CAC scheme.     

QoS Differentiation for IEEE 802.16 WiMAX Mesh Networking

Recently IEEE 802.16 WiMAX has attracted a lot of attention in wireless networking research and applications. To enable a flexible and cost-effective deployment, mesh networking mode is defined in WiMAX standard. In this paper, we introduce a system model of WiMAX mesh networking with the focus on entry process, frame structure, centralized and distributed scheduling. The state-of-the-art WiMAX mesh networking research is reviewed. In addition, we propose an effective QoS differentiation scheme for the IEEE 802.16 WiMAX mesh networks. Both collocated scenario and general topology are theoretically analyzed and compared. Illustrative numerical examples are presented to demonstrate the effectiveness of the proposed strategy. The impact of key parameters on the performance is discussed for differentiating multiple classes of services. Several open issues are summarized as a guideline for future topics in WiMAX mesh networking research.     

Resource Management and QoS Provisioning for IPTV over mmWave-based WPANs with Directional Antenna

There is an increasing interest in 60 GHz millimeter-wave (mmWave) communication technologies for multi-Gigabit wireless personal area networks (WPAN), aiming to support broadband multimedia applications. Internet Protocol TV (IPTV) is an emerging killer application which requires high data rate and stringent quality of services (QoS) in terms of delay and packet loss. In this paper, we propose a method to efficiently support high definition video flows in a mmWave-based WPAN with QoS guarantee, considering the characteristics of both the IPTV traffic and the mmWave communication technology. We first quantify the effective bandwidth of IPTV video sources using a simple, two-level Markov traffic model. Considering the overheads of the protocol stack in mmWave WPANs, we then quantify the minimum channel time needed for each IPTV flow. Since mmWave-based WPANs will deploy directional antennas to not only extend the transmission range, but also reduce the interference level to neighboring flows, we further propose an admission control scheme and scheduling algorithm to improve the network resource utilization by taking advantage of concurrent transmissions. Extensive simulations with NS-2 using real video traces have validated our analysis and demonstrated the efficiency and effectiveness of the proposed schemes, which will be an enabling technology for future mmWave-based WPANs supporting IPTV services. Part of this work was presented at 2008 Int. Conf. Heterogeneous Networking for Quality, Reliability, Security and Robustness (QShine’08), Hong Kong, July 2008. This work has been supported by research grants from the Natural Sciences and Engineering Research Council (NSERC) of Canada.     

Performance Evaluation of the IEEE 802.16 MAC for QoS Support

The IEEE 802.16 is a standard for broadband wireless communication in metropolitan area networks (MAN). To meet the QoS requirements of multimedia applications, the IEEE 802.16 standard provides four different scheduling services: unsolicited grant service (UGS), real-time polling service (rtPS), non-real-time polling service (nrtPS), and Best Effort (BE). The paper is aimed at verifying, via simulation, the effectiveness of rtPS, nrtPS, and BE (but UGS) in managing traffic generated by data and multimedia sources. Performance is assessed for an IEEE 802.16 wireless system working in point-to-multipoint (PMP) mode, with frequency division duplex (FDD), and with full-duplex subscriber stations (SSs). Our results show that the performance of the system, in terms of throughput and delay, depends on several factors. These include the frame duration, the mechanisms for requesting uplink bandwidth, and the offered load partitioning, i.e., the way traffic is distributed among SSs, connections within each SS, and traffic sources within each connection. The results also highlight that the rtPS scheduling service is a very robust scheduling service for meeting the delay requirements of multimedia applications     

IEEE802．16资源分配方案研究

未来移动通信系统,诸如IEEE802.16旨在能够传送多种具有不同QoS要求的多媒体业务.为了保证业务的QoS,需合理设计调度器的结构和相应的调度算法.针对IEEE 802.16宽带无线接入系统中的双层分级带宽分配体系结构,结合总调度器分配算法优点,采用了更适用于分类调度器且不同于     

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。     

IEEE 802.16网络中保障QoS的多用户业务调度算法

基于IEEE 802.16协议,研究了宽带无线接入网中保障Qos的上行多用户多业务资源分配和调度问题.首先,对该问题建立跨层分析模型,即基于TDM-OFDMA物理层的多址接入队列调度模型.随后提出了基于凸优化方法的最小剩余聚合工作负载算法.可以证明,只要到达业务的QOS参数值在该算法的稳定域内,那么它就能渐进地保证业务的QoS要求,同时还能最小化调度系统的剩余聚合工作负载.仿真实验的数值结果进一步证明了本算法的确能够在可接受的复杂度范围内保证4类服务的Qos要求.     

Robust QoS Control for Single Carrier PMP Mode IEEE 802.16 Systems

The IEEE 802.16 WirelessMAN standard provides a comprehensive quality-of-service (QoS) control structure to enable flow isolation and service differentiation over the common wireless network interface. By specifying a particular set of service parameters, the media access control (MAC) mechanisms defined in the standard are able to offer predefined QoS provisioning on a per-connection basis. However, the design of efficient, flexible, and yet robust MAC scheduling algorithms for such QoS provisioning still remains an open topic. This paper proposes a new QoS control scheme for single-carrier point-to-multipoint mode wireless metropolitan area network (WirelessMAN) systems, which enables the predefined service parameters to control the service provided to each uplink and downlink connection. By MAC-PHY cross-layer resource allocation, the proposed scheme is robust against particular wireless link degradation. Detailed simulation experiments are presented to study the performance and to validate the effectiveness of the proposed QoS control scheme.     

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.     

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.     

Queue-Aware Resource Allocation for Multi-cell OFDMA Systems with QoS Provisioning

This paper proposes a queue-aware resource allocation algorithm which provides quality of service (QoS) guarantees. The proposed solution adopts a cross-layer design approach since it is aware of both users’ queue buffer states (data link layer) and channel quality state (physical layer). Main advantages of the proposed resource allocation algorithm are: the low computational complexity and its capacity of maintaining lower QoS violation probability than other multi-cellular schemes. The proposed solution can also result in enhanced cell-edge data rate and improved fairness performance. User minimum data rate and target bit error rate as considered as QoS parameters. Validation of the proposed algorithm is achieved through various simulation scenarios wherein QoS violation probability, system fairness, user average data rate and cell-edge throughput are investigated. Numerical results and complexity analysis demonstrate the efficiency and the feasibility of the proposed QoS-oriented approach.     

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。     

IEEE 802.16d上行链路调度服务优化算法

调度算法是宽带无线接入系统为分类业务提供QoS保证的重要手段和工具。本文提出一种用于IEEE802.16d宽带无线接入系统TDD模式下的跨层调度服务的改进算法I_DFPQ。仿真结果表明该算法在各个类型业务流的吞吐量、时延、丢包率和公平性方面相比于同类的其他算法具有更优的性能。     

Joint Dynamic Resource Allocation for QoS Provisioning in Multi-Access and Multi-Service Wireless Systems

This paper proposes a Joint Dynamic Resource Allocation (JDRA) algorithm that allocates simultaneously the best-suited Radio Access Technologies (RATs) and amount of resources to all the users active in a multi-access wireless system. Both distributions are performed at the same time so as to make the most of the heterogeneous network. In this scenario users can connect to several RATs but not simultaneously and, therefore, the JDRA algorithm is able to consider the required handover time in the decision making. Moreover, the algorithm guarantees the Quality of Service (QoS) provision in terms of delay and bit rate in a multi-service scenario where different users may have different QoS requirements. Such a complex optimization problem has been tackled using a Hopfield Neural Network (HNN) formulation. These neural networks have fast response times once hardware implemented, which is very significant since current and future wireless networks must rapidly adapt to changing circumstances in wireless environment and traffic. Results prove the benefits achieved by the usage of the HNN-based JDRA algorithm. Firstly, the joint decision outperforms a two-steps procedure in which, after the RAT selection, the same uni-RAT DRA algorithm is applied. Secondly, the proposed algorithm can deal with different levels of congestion and load distribution among RATs in a much better way that other reference algorithms specifically designed for multi-service scenarios.     

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。     

宽带CDMA IP网中实现区分服务的QoS结构

3G CDMA网提供高速无线IP服务,其业务主要包括数据、语音互式多媒体。为了能保证这些异构业务的QoS,并提供业务区分,将有线IP网的分区服务（DIFFSERV）QoS模型引入3G CDMA网络。针对无线网络的终端移动性、高丢失率、更低的网络带宽等特点,对原有的DIFFSERV结构进行了修改,给出了基于DIFFSERV的无线QoS结构,并简单描述了实现协议。还给出了有效带宽的录入控制策略和资源预留策略来实现QoS。通过仿真,研究了各种策略的性能。     

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。     

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.     

Resource management for symmetrical applications over heterogeneous services in IEEE 802.16

Wireless Networks - Symmetrical applications are multimedia applications that require both uplink and downlink connectivity. The demands of symmetrical applications are expected to grow rapidly in...