无线传感器网络中基于信息质量的跨层QoS支持

本文中提出了一种基于数据的信息质量而提供QoS支持的跨层协议，文中先阐述了无线传感器网络与传统网络在QoS支持上的不同的需求和特点，并提出了跨层优化的概念，指出无线传感器网络采用跨层优化的可行性和必要性？本文通过划分优先级来对网络提供不同的服务质量．数据包的优先级主要反应了数据包中所含的信息质量，由网络的应用层决定，而后再根据数据优先级的不同在MAC层提供不同的服务，从而实现跨层的QoS支持。     

业务驱动的无线多媒体传感器网络跨层优化

由于无线多媒体传感器网络链路动态变化、节点移动、带宽和能量受限等特点,传统的分层协议及其局部优化很难保证整个网络性能最优。为实现无线传感器网络中多媒体业务保障服务质量(QoS),提出一种基于业务驱动和自反馈机制的无线多媒体传感器网络跨层优化策略。该策略按照保证QoS等级最高业务服务质量原则,自适应优化网络协议栈各层参数,并将优化后参数反馈给相应网络协议层,实现保证QoS的网络资源优化,仿真结果表明,该方法在综合物理层误码率和链路层数据帧丢失率的情况下,与传统网络分层协义相比,提高多媒体信息传输质量方面有一定优越性。     

改进的遗传算法无线视频传感器网络协作路由技术研究

提出了适用于无线视频传感器网络的基于能量感知的跨层交互多路径协作路由技术.该技术首先采用了基于视频传感器节点感知距离的遗传优化算法,预测传输视频数据的能耗和剩余能量,结合无线信道质量和视频编码算法建立一种跨层协同的工作体系,优化节点传输视频数据的能耗、时延和带宽等因素;然后建立应用层、网络层和物理层跨层协同工作体系.仿真实验和数学分析表明,该技术不仅能够较好地满足视频传感器网络应用业务的多样性QoS数据传输性能需求,而且可以充分利用视频传感器网络受限的计算、存储能力和能量等资源.     

基于蚁群优化的多媒体传感器网络实时视频流分发策略

视频流传输是无线多媒体传感器网络的研究热点.本文提出一种基于蚁群优化的实时视频流分发策略AVSD(ACO based video streaming dissemination),分路由建立,节点内部视频数据分发两个阶段.在现有视频编码技术基础上,利用蚁群优化寻找具有不同QoS保障的路径,进行区分优先级的数据分发.仿真结果表明,AVSD策略可有效降低端到端时延,合理利用全网资源,提高网络性能并能够为无线多媒体传感器网络提供较好的视频传输性能.     

一种结合业务区分的S-MAC协议

针对无线传感器网络中S-MAC协议没有考虑网络的QoS性能问题,本文提出了一种结合业务区分的S-MAC协议,令优先级不同的节点获得不同的接入信道概率,提高了传感器网络的QoS性能。仿真结果显示,改进后的S-MAC协议确实提高了网络的QoS性能。     

一种结合业务区分的S-MAC协议

针对无线传感器网络中S-MAC协议没有考虑网络的QoS性能问题,本文提出了一种结合业务区分的S-MAC协议,令优先级不同的节点获得不同的接入信道概率,提高了传感器网络的QoS性能。仿真结果显示,改进后的S-MAC协议确实提高了网络的QoS性能。     

一种基于DiffServ的IP电话QoS实现方案

如何为IP网络中的业务提供QoS保证正成为lP技术所要解决的关键问题。文中基于Diffserv提出了一种IP电话QoS方案，并对其基本思想及实现方法作了详细介绍。该方案将不同的分组数据包设置成不同的优先级，其中系统控制分组数据包优先级最高，语音分组数据包次之，普通数据分组数据包最低，使得系统控制分组和语音分组数据包的平均等待时间缩短。研究结果表明，对不同数据包进行优先级设置是改善IP电话QoS的一种可行方法。     

一种无线传感器网络的多优先级数据聚集协议

无线传感器网络当前已成为一种新的分布计算模式，由于大部分无线传感器网络中节点的能源是不可补充的，因此需使用数据聚集协议提高整个网络的生命周期，传统的数据聚集协议不能保证网络中的高实时性数据的延迟较低．文中提出的DAIDA协议根据节点上的流量状况及数据的不同优先级要求自适应地调整数据链路层发送的数据包的大小，模拟结果表明，高实时性数据通过网络的延迟低于低实时性数据的延迟，并且延长了无线传感器网络的生命周期。     

基于最优连通功率控制的WSNs跨层路由优化算法

针对非连通区域节点空洞效应和热点区域节点间通信干扰导致的路由服务质量（QoS）下降问题,提出了一种基于最优连通功率控制的无线传感器网络（WSNs）跨层路由优化算法。算法采用自适应最优连通功率控制策略,在避免路由空洞产生和保证网络连通性条件下,降低热点区域节点数据转发竞争干扰;通过位置信息、剩余能量和干扰等级的跨层信息交互,动态选取最优转发节点,提高网络整体性能。仿真实验表明：算法能够提高路由（QoS）、优化网络生命周期和降低热点区域通信干扰。     

一种服务区分的多媒体传感器网络MAC协议

为在资源受限的无线传感器网络中传输具有不同业务要求的多媒体信息,提出一种基于服务质量感知和优先级的无线多媒体传感器网络MAC协议——QA-MAC。协议通过有效的服务区分机制,对不同优先级的数据流采用不同的自适应竞争窗口调节方法和占空比调整方法,以保障不同优先级业务的实时传输要求。仿真实验结果表明,与S-MAC协议相比,QA-MAC协议在网络延迟性和数据包传输率方面都有明显提高,随着网络负载的增大,数据包传输率平均可以提高30%以上,能够较好地满足无线多媒体传感器网络应用的需求。     

电力线通信系统中跨层的用户调度和资源分配

针对多用户多业务基于正交频分多址的电力线通信系统,提出一种在数据链路控制层进行用户调度和在物理层进行资源分配的多层多目标最优的跨层资源分配算法,其用户调度根据所有用户的服务质量(QoS)满意程度、QoS要求、业务包模型、信道状态信息和队列状态信息,从所有用户中选出要服务的用户和确定这些用户的最优跨层参数;其资源分配则根据所有调度用户的QoS要求、最优跨层参数和信道状态信息,先把功率按地窖注水原理分给每个子载波,再把每个子载波最优地分给调度用户并采用逐比特加载查表算法调整其上分配的功率和比特。最后在典型的电力线信道环境下对算法进行仿真,结果表明新算法在系统资源大范围变化时也能保障用户的服务质量,同时有效地提高系统资源的利用。     

MHWSN中保证混合业务QoS的跨层调度算法

针对中高速传感器网络中混合业务QoS（Quality of Service）要求,跨层考虑物理层和数据链路层参数,提出了一种保证混合业务服务质量的调度算法AM-LWDF。该算法同时考虑时延优先级和吞吐量优先级,在满足实时业务QoS约束的前提下,以最大化系统吞吐量为目标建立了相应的优化模型,对实时业务能够满足时延较小的要求,对非实时业务满足吞吐量较大的要求。仿真结果表明,该调度算法可以灵活地在时延和吞吐量之间取得满意的折衷,并保证不同类型业务用户间的公平性。     

Joint QoS optimization for layered computational grid

Many existing grid resource allocation and scheduling algorithms mainly focus on isolated layers of the grid architecture. The inflexibility of the strict layering structure results in an inefficient utilization of the grid resources. This paper takes a system view of the computational grid and aims to jointly optimize global QoS by adopting cross-layer design. Cross-layer design is based on information exchange and joint optimization among multiple grid layers. Parameters from different layers are provided to a cross-layer optimizer, which selects the values of the layer specific parameters maximizing joint global QoS. The objective of the paper is to jointly optimize the parameters of all layers in a decentralized optimization problem and decompose joint QoS optimization into three sub problems at fabric layer, collective layer and application layer. In simulation part, we compare the performance of the global joint QoS optimization approach with application layer local optimization and resource layer local optimization approach, respectively.     

Providing adaptive QoS to layered video over wireless local area networks through real-time retry limit adaptation

Robust streaming of video over 802.11 wireless LANs (WLANs) poses many challenges, including coping with packets losses caused by network buffer overflow or link erasures. In this paper, we propose a novel error protection method that can provide adaptive quality-of-service (QoS) to layered coded video by utilizing priority queueing at the network layer and retry-limit adaptation at the link layer. The design of our method is motivated by the observation that the retry limit settings of the MAC layer can be optimized in such a way that the overall packet losses that are caused by either link erasure or buffer overflow are minimized. We developed a real-time retry limit adaptation algorithm to trace the optimal retry limit for both the single-queue (or single-layer) and multiqueue (or multilayer) cases. The video layers are unequally protected over the wireless link by the MAC with different retry limits. In our proposed transmission framework, these retry limits are dynamically adapted depending on the wireless channel conditions and traffic characteristics. Furthermore, the proposed priority queueing discipline is enhanced with packet filtering and purging functionalities that can significantly save bandwidth by discarding obsolete or un-decodable packets from the buffer. Simulations show that the proposed cross-layer protection mechanism can significantly improve the received video quality.     

End-to-end support for statistical quality of service in heterogeneous mobile ad hoc networks

In heterogeneous mobile ad hoc networks (MANETs), different types of mobile devices with diverse capabilities may coexist in the same network. The heterogeneity of MANETs makes end-to-end support for quality of service (QoS) guarantees more difficult than in other types of networks, not to mention the limited bandwidth and frequent topology changes of these networks. Since QoS routing is the first step toward achieving end-to-end QoS guarantees in heterogeneous MANETs, we propose a QoS routing protocol for heterogeneous MANETs. The proposed protocol, called virtual grid architecture protocol (VGAP), uses a cross-layer approach in order to provide end-to-end statistical QoS guarantees. VGAP operates on a fixed virtual rectilinear architecture (virtual grid), which is obtained using location information obtained from global positioning system (GPS). The virtual grid consists of a few, but possibly more powerful, mobile nodes known as ClusterHeads (CHs) that are elected periodically. CHs discover multiple QoS routes on the virtual grid using an extended version of the open shortest path first (OSPF) routing protocol and an extended version of WFQ scheduling policy that takes into account the wireless channel state. Moreover, VGAP utilizes a simple power control algorithm at the physical layer that provides efficient energy savings in this heterogeneous setting. Simulation experiments show that VGAP has a good performance in terms of packet delivery ratio, end-to-end packet delay, call blocking probability, and network scalability.     

Cross-layer optimization policy for QoS scheduling in computational grid

This paper presents a cross-layer quality of service (QoS) optimization policy for computational grid. Efficient QoS management is critical for computational grid to meet heterogeneity and dynamics of resources and users’ requirements. There are different QoS metrics at different layers of computational grid. To improve perceived QoS by end users over computational grid, QoS supports can be addressed in different layers, including application layer, collective layer, fabric layer and so forth. The paper tackles cross-layer grid QoS optimization as optimization decomposition, each layer corresponds to a decomposed subproblem. The proposed policy produces an optimal set of grid resources, service compositions and user's payments at the fabric layer, collective layer and application layer respectively to maximize global grid QoS. The cross-layer optimization problem decomposes into three subproblems: grid resource allocation problem, service composing and user satisfaction degree maximization problem, all of which interact through the optimal variables for capacities of grid resources and service demand. In order to coordinate the subproblems, cross-layer QoS feedback mechanism is established to ensure different layer interactions. The simulations are conducted to validate the efficiency of the proposed policy.     

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。     

一种AODV跨层优化方法及仿真测试分析

针对Ad Hoc网络中传统AODV协议不支持QoS的缺陷,提出了一种多约束QoS AODV跨层优化方法MQ-AODV（Multi-Constrained QoS AODV）。该方法采用跨层设计的思想,除以传统AODV协议的转发跳数作为路由选择判据之外,而且加入应用层的QoS需求信息和MAC层的多种QoS指标作为路由选择判据,并通过改进AODV路由表结构和路由查找算法,提高AODV路由协议性能。仿真测试结果表明MQ-AODV协议缩短了传输时延,增强了路由协议的适应性和鲁棒性。     

Admission control scheme based on priority access for wireless LANs

In order to support the quality of service (QoS) requirements at the medium access control (MAC) layer, the enhanced distributed channel access (EDCA) has been developed in IEEE 802.11e standard. However, it cannot guarantee the stringent real-time constraints of multimedia applications such as voice and video without an efficient method of controlling network loads. In this paper, we propose a measurement-based admission control scheme, which is made up of two parts: priority access and admission control. First, in order to measure the channel status per traffic type, we propose a priority access mechanism in which each priority traffic is distinguished by a busy tone, and separately performs its own packet transmission operation. Then, admission control mechanism protects existing flows from new ones, and maintains the QoS of the admitted flows based on the measured channel status information. Performance of the proposed scheme is evaluated by simulation. Our results show that the proposed scheme is very effective in guaranteeing the QoS of multimedia applications as well as in avoiding the performance starvation of low priority traffics.     

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.