VoIP系统在下一代网络中的QoS保障

针对VoIP系统的质量问题,将3GPP IMS中基于业务的网络策略控制机制融入VoIP的QoS保障中,以SIP作为信令协议,提出具有QoS能力的SIP VoIP系统网络功能结构、QoS分层控制模型。详细分析了其QoS呼叫控制过程,给出了扩展的SIP代理服务器和UE的功能要求以及路由器对QoS信息的支持。新增策略决策功能模块能力,详细分析了上述功能实体之间接口的作用和交互的QoS信息。通过在VoIP系统SIP-QoS代理服务器的各QoS功能模块和原型系统中的应用,验证了模型的可行性和有效性。     

基于分布式消息驱动的计算机网络媒体体传输同步机制

提出了具有面向对象和并行计算概念，基于分层和分区的具有良好动态自适应特性的分布式消息同步网络模型。     

WDM光网络中支持QoS的波长分配算法

基于在波长可变光网络中的波长分层图模型,本文提出了一种在动态业务情况下的支持不同QoS要求的路由波长分配算法,根据客户层业务不同的QoS要求,通过分层图模型中参数的不同取值,对其光路建立请求区别对待,提供不同级别的光路建立.仿真结果表明该算法具有很好的性能,提高了全网的资源利用率,满足了客户层业务在建立光通路时不同的QoS要求对网络阻塞率的要求.     

Ad hoc网络中的QoS保障及其相关问题的探讨

由于带宽受限和网络拓扑的动态变化，在Ad hoc网络中支持QoS是一个具有挑战性的任务。目前许多研究组织和大学都在研究和试图解决这个问题。本文首先介绍了Ad hoc网络中提供QoS保证面临的各种困难，然后详细讨论了Ad hoc网络的QoS服务模型、信令机制、QoS路由和支持QoS的MAC协议，接着研究了适合于动态网络的自适应机制中间件框架在Ad hoc网络中的应用。最后对全文进行了总结并提出了今后的工作方向。     

基于分布式消息驱动的计算机网络媒体传输同步机制

提出了具有面向对象和并行计算概念、基于分层和分区的具有良好动态自适应特性的分布式消息同步网络模型。     

认知异构蜂窝网络中改进蜉蝣算法的资源分配策略

针对认知异构蜂窝网络中上行链路资源分配的优化问题,提出认知异构蜂窝网络中改进离散蜉蝣算法的资源分配算法。认知异构蜂窝网络模型中,考虑用户层间干扰和带外干扰引入功率控制策略控制发射功率来干扰抑制,基于用户服务质量（QoS）需求和干扰阈值约束,最大化能量效率为优化目标,利用改进离散蜉蝣算法优化求解得出最优分配方案。引入不完全Gamma和Beta分布函数的动态自适应权重、黄金正弦位置更新策略,提升蜉蝣算法的收敛速度和搜索能力。仿真实验表明,基于接收SINR的闭环功率控制动态调整用户端的发射功率,能有效抑制用户间的干扰,GSWBMA求解资源分配问题具有良好的寻优效率和收敛性能,有效提升系统能量效率和用户传输速率,保证用户QoS需求。     

支持移动无线接入的IP网络QoS保证技术

针对服务质量(QoS)保证技术问题,从移动性、无线链路特性和IP网络传统的QoS保证技术的改进几个方面出发,对下一代支持多种移动无线接入的IP网络中,QoS保证技术的相关研究热点及技术现状进行了分析和总结,并提出了本研究方向QoS分层模型和进一步的研究建议。     

无线多媒体传感器网络QoS路由自适应遗传算法研究

介绍了一种基于自适应遗传算法的无线多媒体传感器网络WMSNs的QoS路由算法。在分析了WMSNs的QoS路由模型的基础上,设计了基于遗传算法的QoS路由算法,并对自适应的遗传算法进行了分析。实验结果表明,采用自适应算法后,在满足网络QoS参数需求的前提下有效地提高了算法的收敛速度,比传统的遗传算法最优结果也要好。     

基于策略的动态自适应MANET网QoS保障技术研究

文章从MANET网QoS研究现状入手,提出了应用于MANET网络端到端的业务QoS保障方案——基于策略的动态自适应MANET网QoS解决方案,阐述了该方案的体系架构及技术实现途径。     

移动代理技术在下一代网络QoS监测中的应用

为了弥补传统网络监测方法在性能、伸缩性以及可扩展性等方面的缺陷，提出了应用移动代理技术的下一代网络QoS监测框架。该框架是分层分布式结构，由中央控制节点层、汇聚节点层和叶节点层构成。在各层中分布有汇聚代理、数据分析代理、数据采集代理和本地故障处理代理等各类移动代理。各种代理具有各自不同的职责，它们相互协调、配合，共同完成QoS监测任务。该框架的可扩展性强，分布式监测效率高，能够降低网络负荷，灵活适应网络拓扑结构的动态变化，并且加快了对QoS劣化现象的响应速度，还能避免在现有的系统中增加新功能时大规模更换升级软件带来的开销。     

QoS-, Queue-and Channel-Aware Packet Scheduling for Multimedia Services in Multiuser SDMA/TDMA Wireless Systems

With the growing demand for wireless multimedia services and continuing emergence of new multimedia applications, it is necessary for the network to provide various levels of quality of service (QoS) while maximizing the utilization of channel resources. This paper presents an adaptive queuing model and a novel cross-layer packet scheduling algorithm for providing differentiated QoS and effective channel utilization in a space-division-multiple-access/time-division-multiple-access (SDMA/TDMA) system. At the medium access control (MAC) layer, we take into consideration the heterogeneous and bursty nature of multimedia traffic and provide for QoS requirements. At the physical (PHY) layer, we exploit the randomness of the physical channel by incorporating opportunistic scheduling and adopting adaptive modulation and coding (AMC). Performance results obtained by simulations show that by employing the proposed queuing model and packet scheduling algorithm, the system is able to provide for diverse QoS and achieve high throughput.     

Proportional degradation services in wireless/mobile adaptive multimedia networks

Adaptive multimedia services are very attractive since resources in wireless/mobile networks are relatively scarce and widely variable, and more importantly the resource fluctuation caused by mobility and channel fading can be mitigated using adaptive services. Therefore, there are extensive research activities on Quality of Service (QoS), call admission control, as well as bandwidth degradation and adaptation for adaptive multimedia services in wireless/mobile networks in recent years. However, fairness of bandwidth degradation has largely been ignored in previous work and remains an important issue in adaptive multimedia service provisioning. In this paper, we propose and study proportional degradation service provisioning in wireless/mobile networks that offer multiple classes of adaptive multimedia services. The proposed proportional degradation fairness model guarantees the proportional bandwidth degradation among different classes of services. Two proportional degradation scenarios are studied in this paper. In the first scenario, we study the proportional degradation provisioning with two QoS parameters for adaptive multimedia: the degradation ratio (DR) and the degradation degree (DD). In the second scenario, we study the proportional degradation provisioning with a new QoS parameter for adaptive multimedia: the degradation area (DA). For each scenario, based on the QoS parameters, proportional degradation adaptation algorithms are proposed to approximate the proportional degradation model, to fairly adapt calls' degradations, to utilize the system resource efficiently, as well as to optimize QoS parameters. Performance studies show that in the first scenario, proportional DR has been achieved very well, whereas proportional DD has not been well achieved. In other words, DR outperforms DD in terms of proportional degradation. In the second scenario, proportional DA has been well achieved. Furthermore, bandwidth resources have been efficiently utilized and DA has been minimized. Copyright © 2004 John Wiley & Sons, Ltd.     

Radio Network Aggregation for 5G Mobile Terminals in Heterogeneous Wireless and Mobile Networks

This paper provides a novel design concept for advanced mobile multi interface terminals with radio network aggregation capability and enhanced quality of service (QoS) provisioning for multimedia services (voice, video and data) in heterogeneous wireless and mobile networks. A new module is established which provides the best QoS and lowest cost for any given multimedia service by using simultaneously all available wireless and mobile access networks for a given traffic flow. This novel adaptive QoS module with adaptive QoS routing algorithm is called advanced QoS routing algorithm (AQoSRA), which is defined independently from any existing and future radio access technology. The performance of our proposal is evaluated using simulations and analysis with multi-interface mobile stations with AQoSRA within, carrying multimedia traffic in heterogeneous mobile and wireless environment with coexistence of multiple Radio Access Technologies, such as 3G, 4G as well as future 5G radio access networks. The analysis of the proposed framework for radio networks aggregation in advanced mobile terminals has shown overall better performances regarding the achievable throughput and multimedia access probability in heterogeneous wireless and mobile environment.     

一种优化无线多媒体业务接入允许控制和资源分配算法

无线网络中的多媒体业务具有很大吸引力。本文将多媒体业务分为实时业务和非实时业务,提出了一种呼叫接入控制优化算法CAC-RA,此算法通过采用马尔科夫方法,排队论和非线性规划模型,同时解决呼叫允许控制和资源优化分配问题。提出的利益函数考虑了最大利用资源,同时满足无线网络各类用户的QoS要求,同时尽量减少用户的资源重新分配的频率和幅度变化,仿真实验数据显示CAC-RA算法能较好地适应业务变化的网络,同时实现了较为理想的利益值,满足无线网络多媒体用户的QoS要求。     

车用自组网媒体访问控制机制改进

为提升车用自组网传输音频、视频的服务质量,对基于IEEE802.11p的车用无线接入技术MAC机制进行改进,提出竞争窗口自适应EDCA机制。仿真实验表明,竞争窗口自适应EDCA机制有效地降低了车用自组网中音频、视频流的传输时延、时延抖动和丢包率,保证了车用自组网传输VoIP、视频会议、音视频流媒体等多媒体业务的服务质量。     

基于漏窗机制实时自适应多媒体同步

本文分析了实时多媒体同步问题以及相关研究,提出了一个基于漏窗机制实时自适应多媒体同步方案,该方案具有算法简单的特点,并且具有良好的自适应能力,可以适应各种网络变化,各种延迟特性,同样也适用于各种媒体类型,完全可以满足实时多媒体同步的需求。     

A customizable QoS strategy for convergent heterogeneous wireless communications

This article proposes a general customizable QoS scenario for heterogeneous wireless access network technologies. The scenario provides robust and flexible QoS support by adapting the amount of resources reserved for the characteristics of the wireless channel, as well as automatic reconfiguration mechanisms of the multimedia encoding rate and error-resilient techniques to adapt to the dynamic mobile communication environment. Two new scenarios, adaptive FEC and MAC-Lite, are introduced to the proposed scheme. These enable a maximizing of the overall performance of the wireless network. The appropriate interfaces within the core network are described for performing end-to-end QoS, which deliver network meters and exchange QoS parameters with the proposed intra and inter cross-layer approaches, including context transfer during handover. Each part, extended by the proposed method can be configured by the application and be independently implemented. To evaluate the proposed scheme, the QoS components were integrated into a trial platform that was built and simulations were then performed. The results demonstrate that the communication quality was significantly improved     

A dynamic quality of service framework for video in broadbandnetworks

A dynamic framework for QoS control of video in distributed multimedia applications is presented. The framework allows flexible and efficient video delivery with application-level QoS support. Key components of the framework are client QoS renegotiation, server source rate control, and dynamic bandwidth allocation. The coordinated functionality of these distributed components provides soft QoS to adaptive applications. A proof-of-concept prototype of a video browser with user-level control of soft QoS is implemented within the proposed framework. The implementation uses a distributed software architecture that represents soft QoS requirements by software objects called service contracts. These objects are exchanged among servers, network nodes, and clients to achieve distributed soft QoS control. Experiences with the prototype and its performance are discussed     

QoS Provisioning in Wireless/Mobile Multimedia Networks Using an Adaptive Framework

Recently there is a growing interest in the adaptive multimedia networking where the bandwidth of an ongoing multimedia call can be dynamically adjusted. In the wireless/mobile multimedia networks using the adaptive framework, the existing QoS provisioning focused on the call blocking probability and the forced termination probability should be modified. We, therefore, redefine a QoS parameter – the cell overload probability – from the viewpoint of the adaptive multimedia networking. Then, we propose a distributed call admission control (CAC) algorithm that guarantees the upper bound of the cell overload probability. Also, a bandwidth adaptation algorithm which seeks to minimize the cell overload probability is also presented. Simulation experiments are carried out to verify the performance of the proposed CAC algorithm. Furthermore, the performance of the adaptive wireless/mobile network is compared to that of the existing non-adaptive wireless/mobile networks. As a further step in QoS provisioning, we propose another QoS parameter, the degradation period ratio, and discuss analytically how the CAC algorithm guarantees the upper bound of the degradation period ratio.