IEEE 802.16 宽带无线接入系统中QoS 机制的研究及展望

IEEE 802.16是第二代宽带无线接入网络的标准之一, 在其网络上为各种业务提供服务质量(QoS)保证是一个非常重要的问题。本文详细介绍了802.16媒体接入控制层(MAC)中的四种上行 QoS 业务类型及其特点,并对其中的参数进行了比较。在此基础上,分析比较了现有的各种业务调度算法,并针对不同业务类型建议了几种相应的调度算法。最后探讨了这个领域存在的问题以及可能的研究方向。     

IEEE 802.16m标准的最新进展

IEEE 802.16标准的进展WiMAX基于IEEE 802.16空中接口规范,目前已成为国际上影响力最大的宽带无线接入技术。WiMAX系列标准主要包括固定接入的802.16d及移动接入的802.16e两个空口接口标准。在这两大基本规范下,802.16标准组织同时还着手制定其它的辅助规范,     

移动宽带无线接入技术IEEE 802.16e综述

介绍了实现移动宽带无线接入的关键技术、IEEE802．16e移动无线宽带接入标准及其物理层与MAC层技术，并与IEEE802．20移动无线宽带接入标准进行了简单比较。     

IEEE802．20宽带无线接入技术

目前，一种新的无线通信标准——IEEE802．20对3G的部署提出了挑战．IEEE802．20也被称为移动宽带无线接入(MBWA)技术。本文对IEEE802．20(MBWA)技术进行了较详细的介绍，分析了IEEE 802．20的协议模型，对该技术的特点和优点进行了概括．最后，本文还介绍了IEEE802．20技术的网络体系机构及其协议，并指出了它的不足。     

IEEE宽带无线接入技术

IEEE国际电子电气工程师协会是宽带无线接入技术的积极推动者。在宽带无线接入方面，IEEE已经制定了802．1I WLAN无线局域网标准和802．16固定宽带无线接入标准，并且成立了专门的工作组研究制定802．20下一代MBWA移动宽带无线接入技术标准。下面对这三个技术标准分别做更为详细的介绍。     

WiMAX无线接入技术

1．引言 WiMAX（World interoperability for Microwave Access）是一种基于IEEE802．16标准的宽带无线接入城域网（Broadband Wireless Access Metropolitan Area Network）技术，最高可以提供75Mb／s的传输率，单基站覆盖范围最大可达到48千米。WiMAX能应用于很多领域，包括“最后一公里”接入、热点、蜂窝回程技术以及商业用户的企业级连接。     

IEEE802.16e移动宽带无线接入技术

对802.16e进行了较为详细地介绍和分析,包括基本特点、主要应用、空中接口规范协议模型、物理层、MAC层等.     

IEEE 802．20：移动宽带无线接入

介绍了无线通信标准——IEEE802．20的总体,给出了标准的研究范围和设计目标,描述了标准的系统结构和技术规范,讨论了物理层和媒体接入控制层的无线接口特性,与IEEE802．16e和现存的3G标准进行了比较,提出了IEEE802．20标准的优势。     

基于IEEE 802的宽带无线接入技术

介绍了基于IEE802的宽带无线接入技术．包括WiFi、WiMAX和IEEE 802.20的特点．并分析了三种技术的联系和区别。由于基于IEEE 802的宽带无线接入是最新热点技术。又进一步分析了它们将对业务提供方式产生的影响。最后，还分析了它们对宽带无线业务价值链的影响。     

IEEE 802.16标准

文章介绍了支持宽带无线接入系统的空中接口标准IEEE 802．16的制订进程、发展现状和趋势，并重点对标准媒体访问控制（MAC)层和物理层的技术特点进行了分析。文章指出IEEE 802．16标准为宽带无线接入网的开发和应用提供了很好的平台，随着宽带业务的快速增长，将成为未来无线接入技术的发展方向之一。     

基于IEEE 802.16a的宽带无线接入系统

IEEE802.16a是固定宽带无线接入系统最新国际标准,基于该标准的宽带无线接入系统在无线传输方面具有调制方式动态选择的特点,可支持多业务;介绍的宽带无线接入系统具备IEEE802.16a建议的物理层、MAC子层、业务汇聚子层、及加密子层等实体,同时描述了一个实际的宽带无线接入系统必须具备的业务接口处理及系统管理等实体,并给出了各实体间的关系。     

Broadband wireless access solutions based on OFDM access in IEEE802.16

Broadband wireless access is the most challenging segment of the wireless revolution since it has to demonstrate a viable alternative to the cable modem and DSL technologies that are strongly entrenched in the last mile access environment. The Analysis, Research, and Consultancy (ARC) Group forecasts that the fixed wireless deployments in both homes and businesses will reach almost 28 million by 2005, with North America and Western Europe accounting for 24 percent and 27 percent of these, respectively. Whether the promise of BWA will materialize depends on its appeal to telecom operators from the perspective of deployment economics, where the critical factor is the ease of installation of broadband wireless subscriber units. This ultimately leads to nonprofessional installation of integrated all-indoor BWSUs. Consequently the physical layer (PHY) has to mitigate the very tough impairments that characterize these non-line-of-sight environments. In this context we overview the work of the one of the IEEE 802.16 standard subcommittee projects that deals with a BWA solution based on OFDM access (OFDMA) aiming at the most challenging NLOS scenarios     

The IEEE 802.16 Working Group on broadband wireless

This article describes the new initiative on broadband wireless access (BWA) that has formed Working Group 802.16 in the IEEE 802 LAN/MAN Standards Committee. The aim is to provide the reader with highlights of the IEEE 802 activities in order to enable better dissemination of these standards into marketable products as well as seek new ideas to be brought into the IEEE 802 arena. BWA systems, utilizing base stations to provide broadband data to business or homes, offer an alternative to wired “last-mile” access links using fiber, cable, or telephone lines. As illustrated, the base stations may be either terrestrial, in orbit, or mounted on airplanes or dirigibles in the stratosphere. The customer terminals can carry two-way communications for Internet access, digital video, telephony, and other services     

IEEE 802.16/WiMAX-based broadband wireless access and its application for telemedicine/e-health services

In this article we investigate the application of IEEE 802.16-based broadband wireless access (BWA) technology to telemedicine services and the related protocol engineering issues. An overview of the different evolutions of the IEEE 802.16 standard is presented and some open research issues are identified. A survey on radio resource management, traffic scheduling, and admission control mechanisms proposed for IEEE 802.16/WiMAX systems is also provided. A qualitative comparison between third-generation wireless systems and the IEEE 802.16/WiMAX technology is given. A survey on telemedicine services using traditional wireless systems is presented. The advantages of using IEEE 802.16/WiMAX technology over traditional wireless systems, as well as the related design issues and approaches are discussed. To this end, we present a bandwidth allocation and admission control algorithm for IEEE 802.16-based BWA designed specifically for wireless telemedicine/e-health services. This algorithm aims at maximizing the utilization of the radio resources while considering the quality of service requirements for telemedicine traffic. Some performance evaluation results for this scheme are obtained by simulations     

Energy saving mechanism in the IEEE 802.16e wireless MAN

In this paper, we study energy consumption for the IEEE 802.16e broadband wireless access (BWA) network, A mobile subscriber station goes to sleep-mode after negations with the base station and temporarily wake-up periodically for a short interval to check whether there is downlink traffic to it to decide whether it goes to wake-mode or continues to be in the sleep-mode. The sleep interval is increased exponentially upon no arrival traffic. We analytically model the sleep-mode scheme and validate the model with simulations.     

A bandwidth request reiteration mechanism for IEEE 802.16 wireless networks

The IEEE 802.16 is a leading technology for Broadband Wireless Access (BWA), where a Base Station (BS) provides a set of Subscriber Stations (SSs) with first-mile network access. Each SS has multiple connections directed to the BS, which are assigned bandwidth on a demand basis. Specifically, the BS allocates part of the channel as request slots, which are accessed by best-effort connections in a random access manner to transmit bandwidth requests. Although bandwidth requests sent by different SSs may collide the standard does not specify an explicit acknowledgment mechanism. This, and the bandwidth being assigned by the BS to each SS as a whole, may lead to critical inconsistencies between the perception of the SSs’ requirements at the BS and the actual SSs’ requirements, which in turn may entail SS service disruption. While the standard suggests that an SS should regularly update the BS about the backlog of its connections, the algorithm to do so is left unspecified. In this paper we propose a simple, yet effective, mechanism to be employed by the SSs, called Bandwidth Request Reiteration (BR²), which prevents deadlock from occurring. Using detailed packet-level simulation, we compare BR² to an alternative approach based on timeout, and show that BR² achieves better performance, in terms of the average transfer delay, while it does not incur a significant additional overhead, in terms of MAC signaling.     

IEEE 802.20: mobile broadband wireless access

This article provides a survey of the emerging IEEE 802.20 standard, also known as mobile broadband wireless access. It provides an introduction to the activities with regard to this standard, including purpose and scope that the specification defines. The relationship with other similar standards such as IEEE 802.16e and 3G are discussed as well. Various technical details of the standard are presented, including quality of service parameters, data rates available to end users, application support, and security. Characteristics that the air interface should provide, specifically in regard to the physical and medium access control layers, are detailed as well     

Real-time CBR traffic scheduling in IEEE 802.16-based wireless mesh networks

This paper studies packet transmission scheduling for real-time constant-bit-rate (CBR) traffic in IEEE 802.16-based wireless mesh networks. We first formulate and solve the scheduling problem as a binary linear programming problem. The computational complexity of the optimum scheduling solution may prevent it from being implemented in practice. We then propose a heuristic scheme, namely bottleneck first scheduling scheme, where scheduling decisions at stations (base station or subscriber stations) with higher traffic loads are done before those at stations with lower traffic loads. At each station, scheduling decisions for CBR packets with more hops to their destinations are done first. Numerical results show that the proposed scheduling scheme achieves the same capacity as the optimal one while obtaining satisfactory delay performance. Dongmei Zhao received the Ph.D. degree in Electrical and Computer Engineering from the University of Waterloo, Waterloo, Ontario, Canada in June 2002. Since July 2002 she has been with the Department of Electrical and Computer Engineering, McMaster University, Hamilton, Ontario, Canada where she is an assistant professor. Dr. Zhao’s research interests include modeling and performance analysis, quality-of-service provisioning, access control and admission control in wireless networks. Dr. Zhao is a member of the IEEE and a registered Professional Engineer of Ontario. Jun Zou received the B.S. and M. Eng. Degrees from Tianjin University, China in 1999 and 2002, respectively. He worked at Siemens Communication Networks Ltd., Beijing from 2002 to 2004. Currently, he is a Ph.D. student at McMaster University, Canada. His research interests include wireless networking, routing protocols, architecture of next generation networks, network security and their applications in telecommunication industry.     

An efficient energy saving mechanism for IEEE 802.16e wireless MANs

This paper presents an energy conservation scheme, Maximum Unavailability Interval (MUI), to improve the energy efficiency for the Power Saving Class of Type II in IEEE 802.16e. By applying the Chinese Remainder Theorem, the proposed MUI is guaranteed to find the maximum Unavailability Interval, during which the transceiver can be powered down. The proposed MUI only dynamically adjusts one parameter defined in the standard. In addition, it is fully compatible with 802.16e standard. We also propose a new technique to reduce the computational complexity when solving the Chinese Remainder Theorem problem. Simulation and analysis have been conducted to evaluate the performance.     

Rogue-base station detection in WiMax/802.16 wireless access networks

We address the problem of detecting a rogue base station (Bs) in WiMax/802.16 wireless access networks. A rogueBs is a malicious station that impersonates a legitimate access point (Ap). The rogueBs attack represents a major denial-of-service threat against wireless networks. Our approach is based on the observation that inconsistencies in the signal strength reports received by the mobile stations (Mss) can be seen if a rogueBs is present in a network. These reports can be assessed by the legitimate base stations, for instance, when a mobile station undertakes a handover towards anotherBs. Novel algorithms for detecting violations of received signal strength reports consistency are described in this paper. These algorithms can be used by an intrusion detection system localized on the legitimateBss or on a global network management system operating theBss.