基于支持区分服务带宽预测的移动自组网QoS路由协议

已有移动自组网QoS路由协议的研究假设节点的可用带宽信息已知,主要侧重在协议的寻路算法和如何降低网络开销.而已有的带宽预测方法没有考虑通信的业务类型,预测结果不够准确.本文提出一种支持区分服务的可用带宽预测模型,该模型不仅考虑了节点之间信道争用的影响,而且从具有不同优先级的业务角度出发对可用带宽进行预测.在该模型的基础上,我们进一步对AODV协议进行扩展,使其支持QoS特性.仿真结果表明本文带宽预测模型能有效地对可用带宽进行预测,扩展后的AODV协议也可提供较好的QoS性能.     

新型无线Mesh网络的QoS路由判据与算法

针对无线网状网络中采用何种路由判据进行路由选择以增大网络吞吐率的问题,在分析现有路由选择准则不足的基础上,通过综合考虑链路的可用带宽、延时、可靠性和干扰等因素对链路OoS的影响,提出了一种新的综合QoS路由准则和算法IRMQOS,并通过仿真验证了该路由准则和算法的可行性.仿真实验结果表明,该方法能显著提高网络吞吐率.     

基于802.11的无线Mesh网络可用带宽估计方法

可用带宽估计方法是提高网络QoS水平的关键技术.通过分析无线Mesh网络的特点与无线信号通信的特征,并建立信号信道容量与发送功率和接收功率在理想通信系统中的数量关系,建立了可用带宽与发送功率和接收功率的数量关系,提出了通过计算无线Mesh网络节点信号容量来估计无线Mesh网络链路可用带宽的方法,从而使得可用带宽估计方法在无线Mesh网络的估计结果更接近真实值.实验结果表明,该方法估计的结果更接近真实的可用带宽,在无线Mesh网络中的精确度要高于APEAB方法,可以为网络管理、流量控制和保证Qos提供参考.     

无线传感器网络满足QoS带宽需求 的能量最优路由方案

有效使用片上受限资源以保持最长的生命周期是无线传感器网络的核心问题.QoS路由技术解决了无线传感器网络要求支持多种业务的差别服务和全网范围的资源有效利用的问题.本文提出了一种可以满足QoS带宽需求的能量最优路由发现方法.该方法构建了节点选择模型、能量评价模型和节点能耗权重模型,使用遗传算法利用可用节点集合建立满足QoS带宽需求的能量最优路由.利用Markov链证明该算法是可收敛并且是以指数速度概率强收敛的.另外,通过实验仿真与分析,给出了本文遗传算法的控制参数的选择区间,实验显示本文提出的满足QoS带宽需求的路由发现方法对无线传感器网络具有更好的适应性和更长的网络寿命.     

基于QoS的分布式接纳控制算法

随着人们对移动自组网(ad hoc网络)研究的深入,服务质量(QoS)已经成为了当前的研究热点之一.为了在ad hoc特殊的网络中提供对QoS的支持,必须设计一种针对流的高效的接纳控制算法.通过分析无线信道的特点,提出了估算本地可用带宽和流可用带宽的方法,同时对流的带宽耗费进行了推导,解决了实现接纳控制必须解决的关键问题,提出了一种基于QoS的分布式接纳控制算法.仿真实验证明,接纳控制算法应用到传统的路由协议(比如AODV)中,性能将会大大提高,并且更适合于实时业务的传输.     

多跳无线局域网中的QoS路由(MQR)协议

针对多跳无线局域网(MWLAN)的带宽受限以及网络拓扑动态性等特点,本文提出了一种优化的多跳无线局域网QoS路由(MQR)协议,该协议提出的节点生成树算法可以根据移动节点和AP之间的跳数以及节点剩余能量组织MWLAN的树形网络拓扑;同时,该协议改进了传统的节点剩余带宽估计算法,使得网络节点可用带宽估计更加精确,在寻路过程中根据节点可用带宽信息为数据流提供软状态QoS保证.仿真结果表明,MQR协议可以有效的降低平均寻路确认时延并提高网络带宽利用率,同时,寻路开销和平均端对端分组时延也得到较好的控制.     

基于IPv6的园区网紧链路定位技术的研究

园区网网络可用带宽测量算法的研究是网络研究的首要问题,其中可用带宽又与紧链路是QoS的两个重要指标,在拥塞控制、流媒体应用,以及园区网各种应用服务等方面具有重要的意义.提出了一种在IPv6网络下紧链路定位的新方法,通过在可控制背景流量和实际的网络环境中进行实验数据统计分析,验证了在IPv6网络下紧链路定位方法的准确性、高效性和可行性.     

时延和时延差别受限的最大带宽多播路由分布式算法

本文采用反映网络实时特性的可用带宽代替代价作为第一度量，提出一种基于最大可用带宽路径且满足时延和时延差别约束的QoS实时多播路由分布式启发算法，该算法具有多项式复杂性，并通过分析得到每路径时延和二约束度量之间的关系，有效降低涉及时延和时延差别此类问题的复杂性。仿真实验证明，该算法具有较好的带宽性能。     

一种基于OSPF扩展的预计算QoS路由算法研究

在一个MPLS域，LSPs的建立需要QoS路由协议分发QoS相关的信息和执行QoS路径选择，但是传统的OSPF不支持QoS路由。本文提出并详细讨论了一种0SPF-QoSR路由机制，它是对OSPF路由协议的扩展，基于网络的动态可用带宽资源和流的QoS请求来决定流的QoS LSPs。仿真证明，该机制在丢包率、链路利用率、延时方面的性能优于只考虑最短路径的OSPF。     

无线Ad hoc多媒体网络中的可用带宽估计

在无线Ahhoc网络上传输具有较高性能要求的多媒体业务,需要为这种网络安装某种QoS路由和准入控制机制。而路径可用带宽计算是任何QoS路由算法的核心部分。802.11无线通道是一类基于CSMA机制的传输介质,建立在802.11MAC层上的多跳Adhoc网络存在流内和流间干扰,所以其可用带宽估计需要特别地加以设计。借鉴[2]的基本思想,根据真实试验,论文对[2]中仿真验证的算法做了一些修正,给出了一个简单、实际可行的可用带宽计算方法,并在DSR试验床上进行了验证。     

Ad hoc网络中基于带宽的准入控制研究

在决定无线自组织网服务质量的诸多参数中,可用带宽是至关重要的参数。通过引用泊松分布流量产生器产生数据包的概率和发送数据包的概率,研究由于隐藏节点引起冲突的概率,消除由于节点发生碰撞对可用带宽的消耗。通过分析与推导,建立IIAB算法模型,并将IIAB加载到AODV协议,利用RREQ/RREP对新的业务流进行准许接入和资源预留,在此基础上,提出了新的基于IIAB-AODV协议的准入控制机制。通过NS2网络仿真平台模拟表明：提出的模型提高了估测可用带宽的精度以及基于IIAB-AODV协议的准入控制机制更能够保障和提高网络的服务质量。     

A multi-layer experimental study of multimedia and QoS communication in wireless mesh networks

A significant issue in Mesh networks is to support multimedia transmissions while providing Quality of Service (QoS) guarantees to mobile users. For real-time multimedia streaming, unstable throughput or insufficient bandwidth will incur unexpected delay or jitter, and it remains difficult to provide comprehensive service guarantees for a wireless mesh environment. In this paper, we target the problem of providing multimedia QoS in wireless mesh networks. We design and implement a campus test-bed for supporting multimedia traffic in mobile wireless mesh networks, and investigate in detail some possible improvements on a number of layers to enable multimedia transmission over wireless networks with QoS support. We first study a number of improvements of some existing routing protocols to support multimedia transmissions. Some new admission control and rate control mechanisms are studied and their performance gains are verified in our experiments. In our new cross-layer adaptive rate control (CLARC) mechanism, we adaptively change the video encoder’s output bit rate based on the available network bandwidth to improve the quality of the received video. We also design a mobile gateway protocol to connect the MANET to Internet and a wireless LAN management protocol to automatically manage WLAN to provide some QoS.     

A fair resource allocation protocol for multimedia wireless networks

Wireless networks are expected to support real-time interactive multimedia traffic and must be able, therefore, to provide their users with quality-of-service (QoS) guarantees. Although the QoS provisioning problem arises in wireline networks as well, mobility of hosts and scarcity of bandwidth makes QoS provisioning a challenging task in wireless networks. It has been noticed that multimedia applications can tolerate and gracefully adapt to transient fluctuations in the QoS that they receive from the network. The additional flexibility afforded by the ability of multimedia applications to tolerate and adapt to transient changes in QoS can be exploited by protocol designers to significantly improve the overall performance of wireless systems. This paper presents a fair resource allocation protocol for multimedia wireless networks that uses a combination of bandwidth reservation and bandwidth borrowing to provide network users with QoS in terms of guaranteed bandwidth, call blocking, and call dropping probabilities. Our view of fairness was inspired by the well-known max-min fairness allocation protocol for wireline networks. Simulation results are presented that compare our protocol to similar schemes.     

An efficient joint channel assignment and QoS routing protocol for IEEE 802.11 multi-radio multi-channel wireless mesh networks

With the emerging of video, voice over IP (VoIP) and other real-time multimedia services, more and more people pay attention to quality of service (QoS) issues in terms of the bandwidth, delay and jitter, etc. As one effective way of broadband wireless access, it has become imperative for wireless mesh networks (WMNs) to provide QoS guarantee. Existing works mostly modify QoS architecture dedicated for ad hoc or sensor networks, and focus on single radio and single channel case. Meanwhile, they study the QoS routing or MAC protocol from view of isolated layer. In this paper, we propose a novel cross-layer QoS-aware routing protocol on OLSR (CLQ-OLSR) to support real-time multimedia communication by efficiently exploiting multi-radio and multi-channel method. By constructing multi-layer virtual logical mapping over physical topology, we implement two sets of routing mechanisms, physical modified OLSR protocol (M-OLSR) and logical routing, to accommodate network traffic. The proposed CLQ-OLSR is based on a distributed bandwidth estimation scheme, implemented at each node for estimating the available bandwidth on each associated channel. By piggybacking the bandwidth information in HELLO and topology control (TC) messages, each node disseminates information of topology and available bandwidth to other nodes in the whole network in an efficient way. From topology and bandwidth information, the optimized path can be identified. Finally, we conduct extensive simulation to verify the performance of CLQ-OLSR in different scenarios on QualNet platform. The results demonstrate that our proposed CLQ-OLSR outperforms single radio OLSR, multi-radio OLSR and OLSR with differentiated services (DiffServ) in terms of network aggregate throughput, end-to-end packet delivery ratio, delay and delay jitter with reasonable message overheads and hardware costs. In particular, the network aggregate throughput for CLQ-OLSR can almost be improved by 300% compared with the single radio case.     

Bandwidth Aggregation-Aware Dynamic QoS Negotiation for Real-Time Video Streaming in Next-Generation Wireless Networks

In next generation wireless networks, Internet service providers (ISPs) are expected to offer services through several wireless technologies (e.g., WLAN, 3G, WiFi, and WiMAX). Thus, mobile computers equipped with multiple interfaces will be able to maintain simultaneous connections with different networks and increase their data communication rates by aggregating the bandwidth available at these networks. To guarantee quality-of-service (QoS) for these applications, this paper proposes a dynamic QoS negotiation scheme that allows users to dynamically negotiate the service levels required for their traffic and to reach them through one or more wireless interfaces. Such bandwidth aggregation (BAG) scheme implies transmission of data belonging to a single application via multiple paths with different characteristics, which may result in an out-of-order delivery of data packets to the receiver and introduce additional delays for packets reordering. The proposed QoS negotiation system aims to ensure the continuity of QoS perceived by mobile users while they are on the move between different access points, and also, a fair use of the network resources. The performance of the proposed dynamic QoS negotiation system is investigated and compared against other schemes. The obtained results demonstrate the outstanding performance of the proposed scheme as it enhances the scalability of the system and minimizes the reordering delay and the associated packet loss rate.     

An Efficient Resource Allocation Mechanism for LTE–GEPON Converged Networks

Optical–wireless convergence is becoming popular as one of the most efficient access network designs that provides quality of service (QoS) guaranteed, uninterrupted, and ubiquitous access to end users. The integration of passive optical networks (PONs) with next-generation wireless access networks is not only a promising integration option but also a cost-effective way of backhauling the next generation wireless access networks. The QoS performance of the PON–wireless converged network can be improved by taking the advantages of the features in both network segments for bandwidth resources management. In this paper, we propose a novel resource allocation mechanism for long term evolution–Gigabit Ethernet PON (LTE–GEPON) converged networks that improves the QoS performance of the converged network. The proposed resource allocation mechanism takes the advantage of the ability to forecast near future packet arrivals in the converged networks. Moreover, it also strategically leverages the inherited features and the frame structures of both the LTE network and GEPON, to manage the available bandwidth resources more efficiently. Using extensive simulations, we show that our proposed resource allocation mechanism improves the delay and jitter performance in the converged network while guarantying the QoS for various next generation broadband services provisioned for both wireless and wired end users. Moreover, we also analyze the dependency between different parameters and the performance of our proposed resource allocations scheme.     

一种基于TDMA的Ad Hoc网络QoS路由算法研究

随着多媒体应用的普及,服务质量（Quality of Service,QoS）保证已逐渐成为Ad Hoc网络必须支持的一项重要功能,QoS 路由对实现Qos保证起着非常重要的作用,而带宽又是QoS保证的最重要参数之一,因此提出了一种基于TDMA的带宽约束的Ad Hoc网络QoS按需路由协议。该协议采用了启发式的带宽计算算法。仿真结果验证了协议的有效性,表明该QoS路由协议具有较好的端到端性能,可以满足Ad Hoc网络的路由需求。     

Service level agreements (SLAs) parameter negotiation between heterogeneous 4G wireless network operators

We are currently witnessing a growing interest of network operators to migrate their existing 2G/3G networks to 4G technologies such as long-term evolution (LTE) to enhance the user experience and service opportunities in terms of providing multi-megabit bandwidth, more efficient use of radio networks, latency reduction, and improved mobility. Along with this, there is a strong deployment of packet data networks such as those based on IEEE 802.11 and 802.16 standards. Mobile devices are having increased capabilities to access many of these wireless networks types at the same time. Reinforcing quality of service (QoS) in 4G wireless networks will be a major challenge because of varying bit rates, channel characteristics, bandwidth allocation and global roaming support among heterogeneous wireless networks. As a mobile user moves across access networks, to the issue of mapping resource reservations between different networks to maintain QoS behavior becomes crucial. To support global roaming and interoperability across heterogeneous wireless networks, it is important for wireless network operators to negotiate service level agreement (SLA) contracts relevant to the QoS requirements. Wireless IP traffic modeling (in terms of providing assured QoS) is still immature because the majority of the existing work is merely based on the characterization of wireless IP traffic without investigating the behavior of queueing systems for such traffic. To overcome such limitations, we investigate SLA parameter negotiation among heterogeneous wireless network operators by focusing on traffic engineering and QoS together for 4G wireless networks. We present a novel mechanism that achieves service continuity through SLA parameter negotiation by using a translation matrix, which maps QoS parameters between different access networks. The SLA matrix composition is modeled analytically based on the G/M/1 queueing system. We evaluate the model using two different scheduling schemes and we derive closed form expressions for different QoS parameters for performance metrics such as packet delay and packet loss rate. We also develop a discrete event simulator and conduct a series of simulation experiments in order to understand the QoS behavior of corresponding traffic classes.