802.11e EDCF信道接入机制的仿真研究

为进一步讨论EDCF(增强的分布式协调功能)数学建模的需要，对802．11DCF(分布式协调功能)和802．11e EDCF信道接入机制的性能进行了仿真分析，讨论了2种信道接人机制的差异，并探讨了EDCF提供QoS的原理，仿真结果表明，EDCF可以为无线局域网提供QoS保证，但在高优先级音频流和视频流过多的情况下，系统性能有所下降。     

非均匀多业务分层网络的资源分配策略分析

研究一种支持多种业务(包括语音对话业务和数据流业务)的分层蜂窝网,在信道共享和信道分割 2 种资源分配策略下的网络性能.网络中的数据流业务根据当前的业务负载情况动态分配带宽,并通过双阈值带宽预留(DTBR)来保证不同业务的不同业务质量(QoS).实验数据显示了在不同业务量情况下2种资源分配方法的性能比较.     

CDMA 网络中基于 QoS 保证的呼叫接纳控制策略

基于CDMA（code division multipleaccess）系统接纳控制（call admission control，CAC）机制没有完全考虑各种多媒体业务的现状，研究了CDMA系统中剩余容量的计算方法，采用更加符合目前无线多媒体网络中业务实际情况的业务模型，给出了一种针对多媒体业务的基于QoS（quality of service）保证的动态CAC算法．分析与仿真结果表明，该算法在保证各种业务QoS要求的情况下，可以显著改善CDMA系统的呼叫等待延时和中断率等性能，提高系统资源的利用率．     

无线Mesh网络的跨层设计理论与关键技术

由于无线M esh网络(WMN)在拓扑、传输和业务上的特性,传统的用于有线网络的分层协议设计方法已不能保证其服务质量(QoS).探索基于物理层、MAC层、路由等协议层的WMN跨层设计方法的目标是在无线资源利用率和多媒体业务的QoS需求两方面达到较好的折衷.WMN各个协议层在设计过程中的有关协议和算法要求附加统一的跨层管理器,监测各层的分组传输性能或需求,动态控制或调节相关算法.通过实现较高协议层的多媒体业务QoS需求与较低协议层的网络状态信息在各协议层之间的共享,可以达到对协议层控制算法的优化.在合理地选择跨层设计目标的基础上,多个协议层需要联合设计与优化.从物理层、MAC层、路由协议层和TCP层等层面介绍了WMN跨层设计的一般原则和方法.归纳了目前WMN跨层设计中亟待深入研究的一些理论和关键技术,包括自适应速率与节能机制、基于QoS需求的跨层MAC协议设计和路由协议设计等.     

无线传感网络中QoS约束多播路由算法

分析了无线传感网络中具有时延、带宽和剩余能量等多QoS约束的多播路由问题.描述了一种适应于研究QoS多播路由的网络模型.提出了一种具有多QoS约束的能量有效的多播路由算法(EMRA),该算法成功地解决了无线传感网络中多播节点动态变化时的QoS路由选择问题.仿真实验证明了EMRA的有效性和优越性.     

基于能效的D2D通信系统中资源复用策略研究

针对D2D通信(device-to-device communication)与传统蜂窝通信共存下的能效资源复用问题,联合考虑蜂窝用户和D2D用户对的QoS约束,结合电路消耗功率,提出一种基于能效的D2D用户对与蜂窝用户最优匹配的资源复用和功率分配策略,分析了D2D用户对复用蜂窝用户资源的最优功率的存在性,并用分式规划理论求解了该最优功率的闭合表达式.仿真结果表明,相比已有算法,所提的能效资源复用策略的D2D用户的总能效最优,并且该总能效在低QoS要求下相比最大化和速率算法提高36.25%,高QoS要求下略高于基于节能的功率分配算法,同时还具有1.7~3 Mbit/s的和速率.      

基于蚁群算法的多QoS约束的多播路由优化算法

蚁群算法是一种新型的随机优化算法,能有效地解决QoS受限的多播路由问题.文中基于蚂蚁具有找到蚁巢与食物之间的最短路径的工作原理,并在分析多约束QoS的多播路由的基础上,提出了一种具有全局优化能力的多播路由算法(OQMRA),仿真实验表明了该算法是合理的和有效的.     

AdHoc网络QoS多径路由协议的研究

QoS路由是提供QoS保证的一种重要手段,但大多数QoS路由是建立在单径的基础上,并没有充分利用Ad Hoc网络资源.文中提出了一种多径QoS路由协议QMPDSR.该协议主要考虑带宽和时延的约束来选择多条QoS路由.当QoS业务到达时,利用一条或多条路径同时传输QoS业务.实验表明,QMPDSR协议提高了分组投递率,降低了时延,路由开销的增加也不明显.     

基于QoS的LTE下行链路调度算法

针对LTE下行资源调度算法中速率自适应优化问题,提出了一种基于服务质量(QoS)的下行链路调度算法,该算法由子载波调度和功率分配两部分构成.为了提高性能和降低算法复杂度,将子载波调度算法和功率分配算法分开讨论,对于基于QoS的子载波分配算法,根据用户的信道质量,合理地分配子载波.在功率分配算法中,根据用户当前时刻的信道状态信息设计各用户的注水线,也即注水因子,使基站动态地为各用户分配功率.最后,通过仿真分析对比改进算法在传输速率、公平性、小区吞吐量以及用户SINR方面的性能,结果表明:改进算法可以很好地降低复杂度,改善用户公平性,降低误码率.     

无线传感器网络环境下的QoS机制研究

在分析了无线传感器网络的QoS需求以及提供QoS需要考虑的问题的基础上,设计了一种基于移动Agent的QoS机制,通过移动Agent的迁移实现网络状态信息的采集与动态QoS指标的调整,在保证网络应用完成的同时延长了网络生命周期。     

Assessment of Quality of Service of Virtual Knowledge Communities

An assessment method for the quality of service (QoS) of virtual knowledge communities (VKC) is proposed based on fuzzy theory and analytic hierarchy process (AHP). The QoS is evaluated in terms of Website design, reliability, responsiveness, trust,personalization, and information quality. The cognitive QoS and the QoS evaluated by assessors are compared to analyze which QoS of the VKC should be improved urgently and which indicators keep leading positions, and to assist administrators of the VKC on measuring and understanding current status and implementation effect of the QoS.     

基于定长帧的组播QoS路由技术

为高效利用网络资源且平衡负载,结合物理帧时槽交换技术,提出了基于定长帧的组播机制和QoS路由算法MRBP.该算法在满足带宽和时延要求的基础上,最小化时延和平衡节点负载,达到组播树总体时延较小并优化利用网络资源的目的.仿真结果表明,基于该算法建立的组播树具有较好的网络负载平衡性,并能够对服务质量提供较好的保证.     

A novel vertical handoff algorithm based on fuzzy logic in aid of grey prediction theory in wireless heterogeneous networks

To coordinate the various access technologies in the 4G communication system, intelligent vertical handoff algorithms are required. This paper mainly deals with a novel vertical handoff decision algorithm based on fuzzy logic with the aid of grey theory and dynamic weights adaptation. The grey prediction theory (GPT) takes 4 sampled received signal strengths as input parameters, and calculates the predicted received signal strength in order to reduce the call dropping probability. The fuzzy logic theory based quantitative decision algorithm takes 3 quality of service (QoS) metric, received signal strength (RSS), available bandwidth (BW), and monetary cost (MC) of candidate networks as input parameters. The weight of each QoS metrics is adjusted along with the networks changing to trace the network condition. The final optimized vertical handoff decision is made by comparing the quantitative decision values of the candidate networks. Simulation results demonstrate that the proposed algorithm provides high performance in heterogeneous as well as homogeneous network environments.     

QoS awared power and admission controls based on non-cooperative game theory in wireless networks

In order to better accommodate heterogeneous quality of service (QoS) in wireless networks, an algorithm called QeS-aware power and admission controls (QAPAC) is proposed. The system is modeled as u non- cooperative game where the users adjust their transmit powers to maximize the utility, thus restraining the interferences. By using adaptive utility functions and tunable pricing parameters according to QoS levels, this algorithm can well meet different QoS reqniremcnts and improve system capacity compared with those that ignore the QoS differ- ences.     

Robust buffer management mechanism in quality of service routers

Active queue management (AQM) is essentially a router buffer management strategy supporting TCP congestion control. Since existing AQM schemes exhibit poor performance and even instability in time delay uncertain networks, a robust buffer management (RBM) mechanism is proposed to guarantee the quality of service (QoS). RBM consists of a Smith predictor and two independent controllers. The Smith predictor is used to compensate for the round trip time (RTT) delay and to restrain its negative influence on network performance. The main feedback controller and the disturbance rejection controller are designed as proportional-integral (PI) controller and proportional (P) controller by internal model control (IMC) and frequency-domain analysis respectively. By simulation experiments in Netwrok-Simulator-2 (NS2), it is demonstrated that RBM can effectively manage the buffer occupation around the target value against time delay and system disturbance. Compared with delay compensation-AQM algorithm (DC-AQM), proportional-integral-derivative (PID) algorithm and random exponential marking (REM) algorithm, the RBM scheme exhibits the superiority in terms of stability, responsiveness and robustness.