建无线城域网——英特尔推介802.16标准和WiMAX组织

9月8日.在“无线网络2003北京”会上,英特尔宽带无线接入总经理 Ron Resnick 先生介绍了802.16标准的发展.以及以积极推广和验证基于802.16标准的宽带无线接入设备的兼容性与互操作性的 WiMAX 组织的进展情况。作为一种新的无线标准.802.16将为运营商级解决方案提供确定的标准,从而可以用单个基站扩充支持成千上万名用户,并提供不同的服务级别。802.16标准是 IEEE 今年1月在802.16a 基础上修正的结果。使用2GHz 到11GHz 频段.作为一种无线城域     

Wimax／802．16e的信息安全研究

通过阐述IEEES02.16e在MAC安全层的体系结构和相关算法及其所采用的安全机制,分析Wimax/802.16d宽带无线访问面对的安全问题及802.16e采取的改进方法,提供Wimax/802.16e网络安全的参考.     

无线城域网IEEE 802．16标准的安全性研究

IEEE于2004年通过了802.16d,以满足无线宽带接入市场的需要.为了进一步提高802.16d的安全性,首先分析了802.16d的协议栈结构及其各子层的作用,然后介绍了802.16d已有的安全机制,其中详细介绍了安全关联SA和PKM协议,最后分析了802.16d仍然存在的安全缺陷,并且提出了相应的改进措施.     

外刊精粹

众所周知,Wi-Fi联盟正努力使802.11x正式确立为无线局域网(WLAN)的标准。最近,Intel公司与WiMAX(全球微波接入互用性)论坛也力推IEEE 802.16和802.16a成为无线城域网(WMAN)的标准。802.16和802.16a是一个在31英里范围内建立峰值数据传输率70Mbps的无线标准(有     

Wimax Mesh模式安全机制研究

IEEE802.16标准（WiMAX）作为一种先进的无线空中接口技术,同样面临着不可规避的无线网络安全问题。在其定义的两种网络模式——PMP模式和MESH模式,特别是在其没有完全定义的MESH网络结构中存在着安全问题。这篇文章将针对该标准定义除PMP模式外的另一种网络结构MESH模式下的安全机制进行分析和研究。通过对MESH模式下的安全分析,本文对原有的安全机制进行了改进。     

IEEE802.16e标准安全机制的改进

指出了IEEE802.16e安全机制中所存在的严重漏洞。针对无线移动设备存在存储容量有限、处理速度慢、带宽低等问题,利用无线公钥设施中的证书标识符URL和椭圆曲线加密算法对IEEE802.16e中的密钥管理协议（PKM）进行了改进。仿真结果表明改进后的安全机制更适合于无线网络环境。     

基于业务流均衡的802.16无线分组调度算法

基于对802.16 2004标准所提出的四种业务流的分析,结合802.16网络的实际应用场景,提出了一种基于业务流均衡的802.16系统无线分组调度算法,并对该算法进行了Matlab仿真类比。仿真结果表明,新算法能够很好地解决分组调度的优先权问题和“饥饿”情况,具有重要的实际意义。     

WiMAX协议的体系结构研究

WiMAX是IEEE802.16标准的通俗称呼。作为一种新兴的宽带无线技术,WiMAX具有其他宽带无线技术难以企及的优势,其单载波传输速率高达75Mb/s,视距传输条件下,基站覆盖范围最大可达50公里,因而成为企业界和学术界的新宠。目前WiMAX产品已经开始部署。文中以802.16d版本为基础,兼顾802.16f标准,对其体系结构进行了深入分析。     

WiMAX协议的体系结构研究

WiMAX是IEEE802.16标准的通俗称呼。作为一种新兴的宽带无线技术,WiMAX具有其他宽带无线技术难以企及的优势,其单载波传输速率高达75Mb/s,视距传输条件下,基站覆盖范围最大可达50公里,因而成为企业界和学术界的新宠。目前WiMAX产品已经开始部署。文中以802.16d版本为基础,兼顾802.16f标准,对其体系结构进行了深入分析。     

IEEE 802.16及WiMAX技术和应用介绍

本文简要介绍宽带无线接入技术(BWA)的技术概要和发展新动态,重点介绍了IEEE802.16标准的物理层技术,并简单讨论了WiMAX与其它无线技术的相容性问题     

Interconnection of CAN segments through IEEE 802.16 wireless MAN

The Controller Area Network (CAN) is a high-performance and highly reliable advanced serial communication protocol, which efficiently supports distributed real-time control. CAN-based distributed control systems have generally two main problems that are the size of distributed area and the need for communication with other LANs and with remote CAN segments. A straightforward solution is to use internetworking devices with wireless support to extend CAN segments. In this paper, a new solution to interconnect CAN segments is proposed, which uses a wireless MAN based on the IEEE 802.16 standard as a backbone system. Also, the solution describing a model for internetworking unit integrates the traffic generated by CAN segments into IEEE 802.16 wireless MAN using encapsulation technique.     

宽带无线移动接入网络中的切换方法

IEEE 802.16e是一种提供用户宽带无线移动接入的新技术。该文针对宽带无线移动通信的特点,在分析IEEE802.16e切换过程的基础上提出一种满足网络服务质量要求并可以在实际系统中工作的切换算法。解决切换中的两个主要问题：切换触发和目标选择。理论分析表明,该算法能够在保证MS良好移动性的同时满足网络中各业务对服务质量的要求。     

一种基于IEEE 802.16的ARQ反馈类型选择算法

IEEE 802.16中规定的ARQ机制能够很好地解决无线链路上的数据传输问题,但是对于规定的几种ARQ反馈方式,协议并没有定义一个合适的选择算法。算法的关键是根据无线链路的实时情况选择一种最合适的ARQ反馈类型来发送反馈消息,从而提高资源利用率。针对IEEE 802.16的特点,提出一种新的反馈类型选择算法,以满足实时选择反馈类型的需求。仿真结果表明,该算法能够显著提高资源利用率。     

Above packet level admission control and bandwidth allocation for IEEE 802.16 wireless MAN

IEEE 802.16 wireless Metropolitan Area Network (MAN) is expected to revolutionize the broadband wireless access technology. Efficient resource management is essential in providing scalability in such large IEEE 802.16-based wireless network and Quality of Service (QoS) for multimedia applications (VoIP, MPEG, FTP, WWW) is usually achieved by appropriate classification of scheduling services and grant/request mechanism. In this paper, we firstly discuss the QoS issue in IEEE 802.16 wireless MANs and propose a dynamic admission control scheme for scheduling services defined in the 802.16 specification. The proposed scheme provides the highest priority for Unsolicited Grant Service (UGS) connections and maximizes the bandwidth utilization by employing bandwidth borrowing and degradation. We develop an approximate analytical model to evaluate the system performance by assuming that the traffic processes of all scheduling services are Poisson processes. In fact, the self-similarity of non-voice traffic makes its traffic process far from Poisson process and should be modeled by Poisson Pareto Burst Process (PPBP). Therefore, in the later part of the paper, we analyze upper bound blocking probabilities of all scheduling services above the packet level using PPBP model for fractal traffic and Gaussian model for aggregated traffic in large wireless network as well as using the Chernoff bound method. Based on the analytical results, we give another admission control and bandwidth allocation mechanism above the packet level so as to minimize the blocking probability of each type of service in IEEE 802.16 wireless MAN. Analytical and simulation results are obtained and compared to demonstrate the effectiveness of proposed schemes and validate our analytical models.     

An efficient bandwidth allocation algorithm for real-time VBR stream transmission under IEEE 802.16 wireless networks

This paper investigates variable rate control strategies for real-time multimedia variable bit rate (VBR) services over IEEE 802.16 broadband wireless networks. A data rate control mechanism is derived for the case where the uplink channel provides real-time services and the traffic rate parameter remains constant. This paper shows that the common queuing scheduling algorithms have some bandwidth allocation fairness problems for the real-time polling service (rtPS) in the MAC layer. In other words, the use of a VBR for the rtPS by a WiMAX system results in additional access latency jitter and bandwidth allocation disorder in the transmitted multimedia streams during the regular time interval polling of subscribe stations (SSs) for the contention bandwidth request period. However, the proposed scheduling algorithm solves these SSs contending with bandwidth resource allocation problems based on an extended rtPS (ertPS) of quality-of-service (QoS) pre-programming for a ranging response non-contention polling period. The adopted bandwidth allocation of max–min fairness queue scheduling uses a time constraint condition to transmit real-time multimedia VBR streaming in an IEEE 802.16 broadband wireless environment. In addition, we use the ns-2 simulation tool to compare the capacity of multimedia VBR stream and show that the proposed ertPS scheduling algorithm outperforms other rtPS scheduling algorithms.     

无线宽带固定接入系统的安全性分析

无线宽带固定接入系统提供了一种高速、灵活的接入方式，文章介绍了802.16标准的认证机制，利用BAN逻辑进行了安全性分析。针对协议分析的结果，提出了基于基站证书的协议的改进。     

Scheduling solution for the IEEE 802.16 base station

The IEEE 802.16 standard defines a wireless broadband access network technology called WiMAX. It introduces several advantages, one of which is the support for QoS at the MAC level. To ensure meeting the QoS requirements, the 802.16 base station must run some algorithm to allocate slots between connections. This algorithm is not defined in the 802.16 specification but rather is open for alternative implementations. We propose a simple, yet efficient, solution that is capable of allocating slots based on the QoS requirements, bandwidth request sizes, and the 802.16 network parameters. To test the proposed solution, we have implemented the 802.16 MAC and PHY layers in the NS-2 simulator. Several simulation scenarios are presented that demonstrate how the scheduling solution allocates resources in various cases. According to the simulation results, the proposed scheduling solution ensures the QoS requirements of all 802.16 service classes. The solution shares free resources fairly and demonstrates work-conserving behaviour.     

WiMAX网络不同模式下的位置管理策略分析

在固定无线城域网基础上支持其移动性的IEEE802.16e[1]是一种有效的移动宽带无线接入解决方案,将HMIPv6[2]与IEEE802.16e有机结合,可以使切换的时延和丢包率都明显减小。IEEE802.16同时支持Mesh模式,可以获得更大的网络覆盖范围以及降低设备成本。本文从理论上分析了在无线Mesh网络中采用传统位置管理策略的网络开销,并与典型的采用HMIPv6的WiMAX网络进行了对比。分析结果表明,WiMAX Mesh网络需要结合拓扑特性考虑更加有效的位置管理策略,以更好地支持移动性及多种业务的应用。     

Analytical model of data transmission in the IEEE 802.16 network

In the wireless networks controlled by the IEEE 802.16 protocol, the subscriber stations reserve the common channel using the mechanism of competitive access. Developed was an analytical model for studying the efficiency of transmission of the upward traffic in IEEE 802.16 network including the processes of channel reservation by the algorithm of multiple random access and packet transmission.