WIMAX系统中PCI接口的设计与实现

WiMAX是基于IEEE 802.16标准的宽带无线接入城域网技术,根据IEEE 802.16标准,用Verilog HDL设计了PCI接口电路,并在FPGA上实现了PCI接口的功能,重点描述了状态机控制模块的设计和仿真结果,使用EDA技术提高了开发速度,满足了系统的要求.     

IEEE 802.16 Mesh模式下基于QoS的时隙分配算法

IEEE 802.16-2004标准定义了Mesh模式下的调度机制，基于这些调度机制下的数据信道资源分配算法，在标准中没有详细规定。该文提出了两种基于优先级的时隙分配算法，以实现MAC层的QoS，通过仿真分析了平均分组延迟、请求失败率和时隙利用率。仿真结果表明这些算法实现了对不同需求的业务流的QoS保障。     

IEEE802．16d系统的帧同步和频率同步研究

基于IEEE 802.16协议的WiMAX技术是目前BWA系统的热点之一,对于NLOS非视距传输环境,IEEE802.16d协议采用了OFDM技术作为调制方式.文章针对OFDM对定时和频偏敏感的问题进行了研究,给出了适用于IEEE 802.16d帧结构的帧同步和频偏估计算法,仿真结果表明该算法具有良好的性能.     

WiMAX系统关键技术的研究

IEEE 802.16标准是一种无线城域网技术,也称WiMAX标准,其技术的完善性对系统性能影响极大,是WiMAX系统商用的关键。该文讨论了WiMAX系统的一些关键技术,随着AMC、MIMO等新技术的应用,WiMAX系统将能支持更高的传输速率。     

基于OPNET的移动WiMAX网络仿真

结合OPNET和IEEE 802.16e协议,采用OPNET的三层建模机制、基于包的通信机制和离散事件驱动机制首次完成对移动WiMAX网络系统级建模.建模内容划分为无线通信网络建模,IEEE 802.16e协议建模,统计信息建模三部分.通过仿真获得了移动WiMAX网络在轻负载情况下的时延性能.     

WiMAX Mesh网络混合调度下的QoS保障

在WiMAX Mesh网络中,资源分配可由集中式和分布式2种调度机制完成,但多数QoS研究只针对一种调度机制。针对上述情况,提出结合2种调度机制的QoS保障机制CDCSQ,针对不同的服务采用不同的调度机制以改进QoS,其中,集中式调度用于保证实时服务,分布式调度确保Mesh内部节点的直接通信。模拟结果表明,该机制比IEEE 802.16标准中的服务延迟小。     

IEEE 802.16中支持QoS的有效带宽分配机制

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。     

基于WiMAX的实时业务带宽优化调度策略

WiMAX是一项无线城域网(WMAN)技术,支持实时与非实时等多种业务,SS可以向BS动态申请所需求的带宽,由IEEE 802.16协议定义.但协议中没有具体定义实时服务QoS所需要的带宽调度策略.因此,如何高效地分配使用带宽,成为一个亟需解决的问题.本文提出一种自适应的实时轮询业务带宽分配策略,SS依据当前带宽需求和以往的实际分配带宽,提前预测实时业务数据包所需求的确切带宽.文中给出了数学分析模型和仿真.仿真结果表明,与传统的带宽分配机制和其他自适应算法相比,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,减少时延和减少缓冲区需求.     

基于OPNET的WiMAX的研究与仿真分析

微波存取全球互通(WiMAX)是一种定位于无线城域网的宽带接入技术,该技术以IEEE 802.16标准为基础,为用户提供范围更广、速率更高的宽带无线接入,因而针对该协议进行网络建模与仿真具有重要的研究价值。在对802.16协议深入研究的基础上,在OPNET仿真环境中设计了仿真模型,基于RTPS算法、NRTPS算法、ERTPS算法进行了仿真分析。     

实现70M无线接入 英特尔宣布开发802.16A芯片

7月10日,英特尔公司宣布将开发基于IEEE802.16a标准的芯片,提供宽带无线接入解决方案,来替代目前的“最后一英里”接入方式。英特尔将通过与Alvarion公司合作,采用英特尔802.16a芯片,开发低成本的WiMAX认证设备。运行于2GHz到11GHz频谱之上的IEEE 802.16a标准是一种无线城域网络(WMAN)技术,利用该技     

An adaptive cross-layer design for multiservice scheduling in OFDMA based mobile WiMAX systems

We consider a cross-layer scheme for the downlink multiuser Orthogonal Frequency Division Multiple Access (OFDMA) for mobile WiMAX (Worldwide Interoperability for Microwave Access) based on IEEE802.16e standard. We propose an intelligent Medium Access Control (MAC) that adapts with the physical layer (PHY) in response to the different QoS requirements of the diverse service flows in the system. This adaptation is represented by a joint packet scheduling and slot allocation scheme interaction in both MAC and PHY layers. Based on this interaction, a fair and efficient QoS guaranteed resource allocation for a mixture of real-time and non real-time service flows is achieved. We provide extensive simulation results showing the performance aspects of the proposed cross-layer scheme.     

WiMAX拓展实时轮询调度机制分析

为了提高无线资源的利用率,使WiMAX系统更好地支持语音业务,基于IEEE 802.16e协议的QoS调度体系,提出了针对带有静默压缩语音业务的拓展实时轮询调度机制的具体实现方案.而且通过对方案中关键参数的分析,给出了一种QoS保证方法.方法根据用户时延对数据带宽分配进行补偿,并按照用户负载情况动态地调整轮询请求带宽的分配周期.使用OPNET软件进行了系统级性能评估,结果表明所提出的方法可有效地降低用户上行接入时延和上行丢包率,从而提高了通信质量.     

Simulator for WiMAX networks

The Network Simulator (ns-2) is a popular tool for the simulation of computer networks; it provides substantial support for simulation of Internet protocols over wired and wireless networks. Although some modules for WiMAX networks simulation have been proposed for the ns-2, none of them implements all MAC features specified by the IEEE 802.16 standard for bandwidth management and QoS support. This paper, however, does present the design and validation of a WiMAX module based on the IEEE 802.16 standard. The module implemented includes mechanisms for bandwidth request and allocation, as well as for QoS provision. Moreover, the implementation is standard-compliant.     

Relay technologies and technical issues in IEEE 802.16j Mobile Multi-hop Relay (MMR) networks

An amendment to the 802.16e standard namely IEEE 802.16j specifying relay station (RS) and multi-hop relay base station (MR-BS) was approved in year 2006 supports Mobile Multi-hop Relay networks. (MMR). It provides coverage extension to isolated area and throughput enhancement by specifying relay stations. The physical (PHY) layer of WiMAX IEEE 802.16j standard is based on the IEEE 802.16-2004 and IEEE 802.16e-2005 standards and was designed from IEEE 802.11a. This paper reviews the Relay technologies and technical issues in the physical and MAC layer of IEEE 802.16j such as Data forwarding schemes frame structure, Link adaptation, modulation and coding, these issues belongs to physical layer, QoS scheduling services, Bandwidth allocation and request, Network planning, MAC handover procedures, connection management, path management, interference management, all these issues belongs to MAC layer.     

A sleep-mode interleaving algorithm for layered-video multicast services in IEEE 802.16e networks

In this paper we investigate efficient mechanisms to support layered-video multicast services in IEEE 802.16e (Mobile WiMAX) networks.¹ Given the bandwidth eager and energy hungry nature of layered-video multicast services, network systems should employ efficient bandwidth allocation and energy saving mechanisms. We first investigate how the WiMAX energy saving mechanisms significantly degrade the performance of multicast bandwidth allocation mechanisms for layered-video multicast services. Then, we present a theoretical model for illustrating this interaction problem. To the best of our knowledge, this paper offers the first investigation into and the first theoretical model of the interaction problem between multicast bandwidth allocation and WiMAX energy saving mechanisms. To solve the interaction problem, we propose a novel sleep-mode interleaving algorithm beyond the existing mechanisms. The proposed algorithm has full compatibility with the existing multicast bandwidth allocation mechanisms and with IEEE 802.16e standards. By appropriately adjusting one sleep mode parameter defined in the standard, the proposed sleep-mode interleaving algorithm effectively guarantees the bandwidth efficiency of the video multicast mechanisms while mobile users can execute the standard sleep mode operations. Simulation results demonstrate the effectiveness of the proposed algorithm in terms of packet delivery ratio, user satisfaction, energy efficiency and computational complexity.     

Highest Urgency First (HUF): A latency and modulation aware bandwidth allocation algorithm for WiMAX base stations

The mobile WiMAX systems based on IEEE 802.16e-2005 provide high data rate for mobile wireless networks. However, the link quality is frequently unstable owing to mobility and air interference and therefore impacts the latency requirement of real-time applications. In the WiMAX standard, the modulation/coding scheme and the boundary of uplink/downlink sub-frames could be adjusted subject to channel quality and the traffic volume, respectively. This provides us a chance to design a MAC-layer uplink/downlink bandwidth allocation algorithm that is QoS/PHY-aware.This work takes into account the adaptive modulation and coding scheme (MCS), uplink and downlink traffic volume, and QoS parameters of all five defined service classes to design a bandwidth allocation algorithm that calculates the slot allocation in two phases. The first phase decides the boundary of uplink and downlink sub-frames by satisfying requests with pending latency violation and proportionating according to traffic volume, while the second phase allocates slots to mobile stations considering urgency, priority and fairness. Simulation results show our algorithm achieves zero latency violation and higher system throughput compared to existing non-QoS/PHY-aware or less-QoS/PHY-aware approaches.     

一种基于IEEE 802.16j网络的带宽调度方案*

针对IEEE 802.16j网络,提出了一种上行业务的动态联合带宽资源调度方案。根据该网络系统树状拓扑结构,在基站BS和中继站RS间采用分级分布式资源调度体制,从而既保障了业务的带宽需求,又提升了上行带宽利用率,同时还提出了针对不同类型业务采用不同的调度算法,改善了调度的公平合理性。仿真结果表明,提出的动态联合调度方案相比严格优先级调度更具灵活性,能够在兼顾用户速率公平的条件下有效地保证各种服务的QoS要求,同时也可获得较高的带宽资源利用率。     

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.