WiMAX中基于QoS的分组调度研究

调度算法是宽带无线接入系统为分类业务提供QoS保证的重要技术。特别是对于复杂多变的无线信道,更具有其特殊的作用和意义。本文首先介绍了宽带无线接入标准WiMAX中MAC层的QoS机制和架构,重点介绍了几种分组调度的算法,并在此基础上提出了一种新的基于QoS的分组调度算法。     

WiMAX系统中的MAC层与网络层接入算法问题探讨

宽带无线接入技术作为无线城域网(Wireless Metropolitan Area Networks)中最具发展潜力的接入技术之一,正受到业界越来越多的关注。IEEE802.15系列规范(也称为WiMAX)的制定,就是为了适应宽带无线接入的快速发展,并为之提供一个全球统一的标准。本文主要研究WiMAX系统网络的常见网络拓扑结构,介绍Mesh网络的帧结构和MAC层的集中式和分布式接入调度算法。     

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     

基于双层分级的无线城域网资源分配方案

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IEEE802.16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参考文献的分配算法,旨在能够针对不同QoS等级的业务提供不同的调度方案,更好地满足用户的QoS要求。     

新型宽带无线接入系统研发进展

宽带无线接入系统已经成为宽带接入和移动通信领域面向未来演化的主体方向之一,但在实际应用和产业推广过程中却遇到了很大困难,需要进一步定位宽带无线接入系统的典型服务模式,推动宽带无线接入关键技术的创新发展,促进宽带互联网络的骨干支撑作用。文章介绍一种宽带无线多媒体接入系统,尝试将地面数字电视系统与宽带无线接入系统结合在一起,以宽带互联网络为核心网平台,共同构建面向＂三网融合＂的新型宽带无线接入网络。初步研究结果表明,新型宽带无线接入系统可有效地缓解当前宽带无线接入系统所面临的尴尬局面,并在业务范畴、业务覆盖、频率规划、终端功耗和建网成本等多个方面取得较大竞争优势。     

新型宽带无线接入系统研发进展

宽带无线接入系统已经成为宽带接入和移动通信领域面向未来演化的主体方向之一，但在实际应用和产业推广过程中却遇到了很大困难，需要进一步定位宽带无线接入系统的典型服务模式，推动宽带无线接入关键技术的创新发展，促进宽带互联网络的骨干支撑作用。文章介绍一种宽带无线多媒体接入系统，尝试将地面数字电视系统与宽带无线接入系统结合在一起，以宽带互联网络为核心网平台，共同构建面向“三网融合”的新型宽带无线接入网络。初步研究结果表明，新型宽带无线接入系统可有效地缓解当前宽带无线接入系统所面临的尴尬局面，并在业务范畴、业务覆盖、频率规划、终端功耗和建网成本等多个方面取得较大竞争优势。     

宽带无线接入系统中基于QoS的调度算法研究

介绍了与宽带无线接入系统相关的QoS内容,包括主要的业务流类型和业务流的管理；然后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。     

U-NII频段宽带无线接入系统

该文介绍了宽带无线接入发展的背景及几种主要的无线接入技术,详细分析了U-NII频段宽带无线接入系统的发展背景、系统组成、系统特点及采用的技术,并指出了U-NII频段宽带无线接入系统与其它频段系统相比较的优势所在。     

中国通信标准化协会简讯

"支持集群业务的SCDMA宽带无线接入系统"系列行业标准审查通过送审稿在无线通信技术工作委员会(TC5)宽带无线接入工作组(WG3)工作会议上,审查通过了"支持集群业务的SCDMA宽带无线接入系统"系列行业标准草案送审稿。支持集群业务的SCDMA宽带无线接入系统基于SCDMA宽带无线接入系统,继承了宽带SCDMA大信道容量、高频谱利用率、抗干扰能力强等诸多优点,可以满足     

基于无线宽带技术的智能配网通信接入方式探讨

无线宽带技术在智能配网通信中的应用,确保了配电系统的正常运转,能够完成对事故的监测、保护和控制,给智能化配网调度各项生产工作的顺利开展提供了支撑性的作用.电力公司为了能够在激烈的市场竞争中取得良好的发展优势,加大了对无线宽带技术的应用,解决了智能配网通信中存在的接入问题.本文无线宽带技术及智能配网通信方式进行介绍,分析了无线宽带技术,对无线宽带技术的职能配网通信接入方式进行详细阐述.     

一种适合高速铁路的宽带无线接入网络架构

快速发展的高速铁路是需要覆盖移动语音和数据业务的新热点场景,这使得高速铁路宽带无线接入系统成为研究重点。根据高速铁路的特定环境,本文提出了一种基于光载无线通信技术的新型高速铁路宽带无线接入网络架构,阐述了相对应的媒体接入控制方案,并对其移动性管理进行了说明。     

A Dual Feedback Approach of Request-Based Bandwidth Allocation for Real-Time Service in Broadband Wireless Access Networks

We propose an efficient request-based uplink bandwidth allocation algorithm for variable-rate real-time service in broadband wireless access networks. By introducing a notion of target delay under the framework of dual feedback, the proposed algorithm can regulate delay while minimizing delay jitter and bandwidth waste.     

一种多射频、多信道无线mesh网络的信道分配算法

宽带无线接入网得到广泛应用,廉价的数据回程带宽是决定宽带无线接入网成功应用的重要因素。丈中设计了一种使用多射频、多信道、方向性天线的新型无线mesh数据回程网,提出了一种基于连接图的等价变换来实现该无线mesh网络信道分配算法。仿真结果表明,文中提出的信道分配算法有效地减少链路间干扰,提高了网络性能。     

An OFDM-TDMA/SA MAC Protocol with QoS Constraints for Broadband Wireless LANs

Orthogonal frequency division multiplexing (OFDM) is an important technique to support high speed transmission of broadband traffic in wireless networks, especially broadband wireless local area networks (LANs). Based on OFDM, a new multiple access scheme, called OFDM-TDMA with subcarrier allocation (OFDM-TDMA/SA), is proposed in this paper. It provides more flexibility in resource allocation than other multiple access schemes such as OFDM-TDMA, OFDM-frequency division multiple access (OFDM-FDMA), and orthogonal frequency division multiple access (OFDMA). With OFDM-TDMA/SA, a medium access control (MAC) is designed for broadband wireless LANs. It optimizes bit allocation in subcarriers so that maximum bits are transmitted in each OFDM symbol under a frequency selective fading environment. The OFDM-TDMA/SA MAC protocol also supports three classes of traffic such as guaranteed, controlled-load, and best effort services. Based on the optimum subcarrier bit-allocation algorithm and considering heterogeneous QoS constraints of multimedia traffic, a hierarchical scheduling scheme is proposed to determine the subcarriers and time slots in which a mobile terminal can transmit packets. In such a way, the OFDM-TDMA/SA MAC protocol significantly increases system throughput in a frequency selective fading environment and guarantees QoS of multimedia traffic. Computer simulation is carried out to evaluate the performance of the OFDM-TDMA/SA MAC protocol. Results show that the new MAC protocol outperforms other MAC protocols for OFDM-based wireless LANs. This work was supported by the State of Georgia Yamacraw Project (E21-105).     

Adaptive MIMO Beamforming Algorithm Based on Gradient Search of the Channel Capacity in OFDM-SDMA Systems

This letter proposes an adaptive beamforming algorithm for uplink access in broadband wireless networks employing orthogonal frequency-division multiplexing with spacedivision multiple access (OFDM-SDMA) technologies. The proposed algorithm seeks, iteratively, the optimal transmit weight vectors that directly maximize the OFDM-SDMA channel capacity for each user in the system, using gradient search of the channel capacity. The analysis and simulation show that the capacity of OFDM-SDMA systems with the transmit weights obtained using the proposed adaptive beamforming algorithm is substantially higher than the one based on conventional approaches such as eigen-beamforming.     

Efficient Uplink Bandwidth Request with Delay Regulation for Real-Time Service in Mobile WiMAX Networks

The emerging broadband wireless access technology based on IEEE 802.16 is one of the most promising solutions to provide ubiquitous wireless access to the broadband service at low cost. This paper proposes an efficient uplink bandwidth request-allocation algorithm for real-time services in Mobile WiMAX networks based on IEEE 802.16e. In order to minimize bandwidth wastage without degrading quality of service (QoS), we introduce a notion of target delay and propose dual feedback architecture. The proposed algorithm calculates the amount of bandwidth request such that the delay is regulated around the desired level to minimize delay violation and delay jitter for real-time services. Also, it can increase utilization of wireless channel by making use of dual feedback, where the bandwidth request is adjusted based on the information about the backlogged amount of traffic in the queue and the rate mismatch between packet arrival and service rates. Due to the target delay and dual feedback, the proposed scheme can control delay and allocate bandwidth efficiently while satisfying QoS requirement. The stability of the proposed algorithm is analyzed from a control-theoretic viewpoint, and a simple design guideline is derived based on this analysis. By implementing the algorithm in OPNET simulator, its performance is evaluated in terms of queue regulation, optimal bandwidth allocation, delay controllability, and robustness to traffic characteristics.     

基于博弈论的移动WiMAX接纳控制

移动WiMAX是一种重要的宽带无线接入技术,它具有数据传输率高、覆盖范围广、支持多种数据业务等优点。为了保证不同业务的QoS,该文提出一种基于博弈论的接纳控制算法。该算法首先给不同的业务赋予不同的优先级,然后建立一个非合作二人博弈模型,通过求解纳什均衡决定是否接纳连接请求,以及带宽的预留方案。仿真结果表明,该算法能够提高带宽的利用率,降低新发起连接的阻塞概率和切换连接的丢弃概率,并且能给不同业务提供区分服务。     

基于DVB-RCS和WiMAX的卫星宽带无线接入体系设计

卫星宽带通信已成为目前研究的热点.现有的DVB-RCS卫星无线接入标准以物理层规范为主,尚未构成完整的卫星宽带无线接人体系.本文基于DVB-RCS技术,针对卫星宽带无线接入的需求和特点,结合地面WiMAX宽带无线接入技术,给出了卫星宽带无线接人体系的功能架构设计,并具体分析了各主要功能的设计与实现方法.     

可生存光纤—无线融合宽带接入网规划方法

光纤—无线融合（fiber-wireless,FiWi）宽带接入网的出现不仅为随时随地的灵活宽带接入提供了新的技术参考,同时也为可生存宽带接入网的低成本设计增加了研究契机。研究了可生存FiWi接入网的网络规划问题,提出一种基于无线重路由保护的可生存网络规划方法。当任意光纤链路断裂时,失效的光网络单元可通过无线重路由将业务转移到其他可用的光网络单元承载。重点解决了无线路由器部署、备份射频接口配置及光网络单元容量分配的联合优化问题,目标是通过最小化网络部署成本实现业务的完全保护。采用整数线性规划方法获得了小规模网络规划问题的最优解,同时提出了适用于大规模网络规划问题的启发式算法。仿真结果证实了所提方法在降低网络部署成本方面的有效性。     

Co-channel interference effects as applied to broadband fixed wireless access channel capacity statistical distribution

Channel Capacity is of primary importance in broadband fixed wireless access (bfwa) networks due to the ever increasing demand for multimedia services and the possibility of providing wireless Internet. One of the major factors limiting capacity in such systems is interference originating from adjacent terrestrial applications belonging to the same bfwa network or to another. Moreover, the performance of broadband fixed wireless access links operating above 10 GHz is predominantly controlled by rain attenuation. The purpose of this paper is the presentation of a physical model for the evaluation of the fraction of the time where the capacity distribution of a broadband fixed wireless access channel under rain fade conditions suffering from co-channel interference, non-exceeds a specified level in (bps/Hz). The proposed analysis examines the capacity distribution properties focusing on the spatial inhomogeneity of rainfall medium. The impact of various operational and geometrical parameters on the performance of interfered broadband wireless access channel capacity distribution is investigated through extended simulations.