一个提高WiMax服务质量的带宽分配调度算法研究

随着接入网络作为连接用户终端与核心网络的纽带的倍受关注,用户越来越关注数据传输的QoS(服务质量)问题。在IEEE802.16协议的MAC层定义了比较完善的QoS机制。但QoS机制中的核心问题,带宽调度算法,协议没有作出明确的阐述和定义。该文在已有典型算法基础上,吸收、采纳了已有算法中适合于IEEE802.16协议的带宽调度的方法,并结合IEEE802.16协议关于QoS的定义,提出了一个针对IEEE802.16协议的PMP(点对多点)模式下集中式的带宽分配调度算法。并在NS2模拟环境下对算法进行了测试。     

以太网无源光网络中的QoS研究

在分析以太网无源光网络系统MAC协议的基础上,研究基于QoS的动态带宽分配机制,提出一种新的支持业务的QoS的动态带宽分配算法。该算法采用限制性带宽分配方法和基于优先级的调度方式,基于业务的通信量特征对各类业务预分配传输带宽。仿真结果表明该算法在时延和吞吐量性能上优于现有算法。     

基于IEEE802.16d PMP网络的业务调度研究

研究无线城域网PMP网络结构TDD模式下媒质接入机制和MAC层调度机制.通过对截断二进制指数算法的研究给出上行调度碰撞解决机制的一种实现方案,在保证QoS要求的同时最优地利用了动态分配的带宽.最后使用NS网络仿真软件对此进行了仿真,给出了UGS和rtPS调度业务数据仿真的结果.     

无线Ad Hoc网络中QoS感知的跨层资源分配算法

在分析无线Ad Hoc网络资源分配模型的基础上,提出一种QoS感知的跨层资源分配算法CL-QARA (cross layer QoS aware resource allocation).其主要思想是,引入价格作为资源分配的度量指标,以QoS带宽需求为参数,将网络层的动态资源分配信息与MAC层CSMA/CA接入机制相结合,以改进MAC层的冲突退避算法.设计了改进的退避算法和呼叫接入控制算法,以实现MAC层与网络层的跨层技术.通过QoS感知的资源分配算法和跨层技术协同工作,为QoS服务提供了业务保障.仿真结果表明,CL-QARA算法具有良好的收敛性和稳定性.与其他算法相比,CL-QARA能够有效地提供QoS保证,提高了网络的效用和性能.     

一种新的Ad Hoc网络QoS源路由框架

该框架采用模块化思想进行设计,由可用带宽计算、接入控制、资源预留、速率控制、拥塞控制等功能模块组成。框架以带宽作为QoS的基本准标,以源路由的方式进行路由查找和数据包投递。框架通过MAC层信道监听与路由层广播相结合的方式对可用带宽进行计算。在路由建立过程中对路径进行筛选,对符合实时流QoS要求的路径进行资源预留。对流量采用速率控制和拥塞控制,避免节点移动性对QoS造成影响。该框架具有可扩展性。仿真实验表明,该框架的QoS保障机制行之有效。     

一种IEEE 802.16宽带无线接入系统的QoS架构

IEEE 802.16 MAC协议虽然对各类业务的QoS提供支持,却没有定义完整的QoS保证机制.本文通过分析IEEE 802.16现有的QoS架构,提出了一种具体的QoS架构,并对相应的调度算法进行了分析.仿真结果表明,该架构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.     

基于IEEE 802.16的接纳控制机制

分析IEEE 802.16的QoS机制,针对其没有详细规定接纳控制算法的情况,结合协议中定义的业务类型QoS特性,在信令交互机制下,提出一种基于优先级的动态带宽分配接纳控制机制。仿真结果表明,与预留带宽的固定带宽分配机制相比,采用该机制后,系统的切换连接掉线率、新增连接的阻塞率和带宽利用率得到改善。     

一种基于IEEE 802.16的动态带宽分配准入控制机制

通过对IEEE 802.16的QoS机制的分析,针对在802.16中没有详细规定准入控制算法的情况,并结合协议中行定义的业务类型的QoS特性和对移动性的支持,提出一种基于802.16的动态带宽分配准入控制机制.仿真结果表明提出的准入控制机制同带宽预留的固定带宽分配机制相比,系统的切换连接掉线率(CDP)、新增连接的阻塞率(CBP)和带宽利用率均有了明显的改善.     

无线局域网IEED 802.11的业务质量机制策略探讨

本文介绍了IEEE802.11标准中所采纳的改进分布协调功能的分布式媒体访问控制方法,它可以为其具有业务质量(QoS)要求的应用提供带有优先权的媒体访问支持,通过与802.11标准的MAC层进行对比分析,指出了82.11标准对MAC层所做的改进.     

带内信令系统实现Ad Hoc网络的邻居预留

提出使用带内信令系统实现跨层的邻居预留机制(NR INSIGNIA),该机制在进行带宽预留时考虑MAC层的信道竞争。节点为某个QoS流预留一定带宽之后,在所有的邻居节点上同时预留等量的带宽,以此来消除信道竞争对带宽预留产生的不利影响。仿真试验对比了没有邻居预留机制的原始INSIGNIA(In band signaling system)系统与NR INSIGNIA系统的性能,结果表明NR INSIGNIA系统可以显著提高QoS流的平均预留包比率、投递率,减少端－端延迟。     

宽带卫星网络中基于跨层设计的带宽分配研究

传统的带宽分配策略按照分层结构进行设计,集中在链路层解决问题,没有考虑动态变化的信道状态和所承载的数据流的QoS性能。基于跨层设计的思想,针对支持话音业务和Internet数据业务的卫星网络提出了一种基于跨层设计的带宽分配算法。该策略将应用层的业务特性和数据链路层的带宽分配策略以及物理层的信道状态进行跨层优化。主控站通过建立代价函数的方法将所有相关参数综合考虑,利用动态规划算法得到了最佳的带宽分配方案。数值结果表明：跨层设计方式可以适应变化的信道状态,并且同传统带宽分配算法比较,提高了Internet数据的有效吞吐量并且保持了话音业务的QoS要求。     

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.     

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.     

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.     

EPON上行链路带宽调度策略研究

EPON作为基于光纤的宽带网络接入技术,已经成为下一代接入网络的关键技术之一,EPON上行链路带宽的竞争机制使得其上行带宽分配算法一直是学术界的热点问题之一。本文对EPON的上行带宽调度方法做了简要概述,提出一种新的EPON上行链路带宽调度策略,易于实现同时兼顾公平性与服务分级。     

无线MIMO系统的上行资源分配算法研究

在存在同信道干扰的无线MIMO系统中,为具有多种QoS需求的调度业务分配资源是一个具有挑战性的问题.提出一种实用的、基于SDMA的贪婪资源分配(SGRA)算法.在高效的干扰管理基础上,SGRA算法可以执行两阶段启发式计算和搜索.在第1阶段,包括上行调度和子信道分配的贪婪资源分配首先在时域频域二维进行;在第2阶段,资源分配被扩展到时域频域空域三维进行.SGRA的算法复杂度低,适用于实际无线通信系统.仿真结果表明,与同类算法相比,SGRA算法可以提高系统吞吐量,更好地保证实时业务的时延和最小数据速率需求,同时兼顾系统公平性.     

A uplink radio resource allocation scheme for localized SC-FDMA transmission in LTE network

The radio resource allocation is one of the most important issues to achieve effective wireless communication. In Long Term Evolution (LTE) network, single carrier frequency division multiple access (SC-FDMA) is applied as the transmission technology for uplink traffic. Most researches focus on maximizing the system throughput of SC-FDMA under changeable channel condition. However, users may require different quality of services (QoS) for different applications. This paper studies radio resource allocation for QoS users in localized SC-FDMA system. The proposed scheme divides allocation process into matching algorithm and radio resource assignment algorithm. The Gale–Shapley algorithm is applied to find the optimal matching between resource blocks (RB) and user equipment (UE) by considering channel conditions and the desired QoS. Then the resource assignment algorithm heuristically allocates bandwidth to UE by referring the matched RB under the constraint of carrier continuity. This paper modified the Recursive Maximum Expansion (RME) algorithm to effectively assign radio resource for UEs with different bandwidth demands. The performance of our proposed scheme is compared with the modified RME scheme through exhaustive simulations. The video streaming, VoIP, and FTP traffic types were adopted for simulations. Our simulation results show that the proposed scheme achieves better QoS satisfaction and system throughput than the RME-modified scheme.     

QoS-aware bandwidth allocation and admission control in IEEE 802.16 broadband wireless access networks: A non-cooperative game theoretic approach

In this paper, we propose an adaptive bandwidth allocation and admission control mechanism based on game theory for IEEE 802.16 broadband wireless networks. A non-cooperative two-person non-zero-sum game is formulated where the base station and a new connection are the players of this game. The solution of the game formulation provides not only the decision on accepting or rejecting a connection, but also the amount of bandwidth allocated to a new connection (if admitted). A queueing model considering adaptive modulation and coding in the physical layer is used to analyze quality of service (QoS) performances, namely, the delay performance for real-time and the throughput performance for non-real-time polling services and best effort service. This queueing model is used by the proposed bandwidth allocation and admission control mechanism to ensure that the utilities for both the base station and the new connection are maximized. The performance of the proposed scheme is evaluated by simulation and compared with that of each of the traditional admission control with static and adaptive bandwidth allocation schemes.