QoS provisioning in cellular networks based on mobility prediction techniques

In cellular networks, QoS degradation or forced termination may occur when there are insufficient resources to accommodate handoff requests. One solution is to predict the trajectory of mobile terminals so as to perform resource reservations in advance. With the vision that future mobile devices are likely to be equipped with reasonably accurate positioning capability, we investigate how this new feature may be used for mobility predictions. We propose a mobility prediction technique that incorporates road topology information, and describe its use for dynamic resource reservation. Simulation results are presented to demonstrate the improvement in reservation efficiency compared with several other schemes.     

Efficient dynamic resource provisioning based on credibility in cloud computing

Wireless Networks - Cloud Computing is a growing technology in which resources are provided as a service. The efficiency in providing the resources as a service depends on various factors. One of...     

QoS provisioning for large-scale multi-ap WLANs

Large-scale deployment of IEEE 802.11 wireless LANs (WLANs) with a high density of access points (APs) has become commonplace due mainly to its potential for numerous benefits, such as ubiquitous service coverage, seamless handover, and improved link quality. However, the increased AP density can induce significant channel contention among neighboring cells, thus causing severe performance degradation and throughput imbalance between cells. There have been a plethora of research efforts to improve the WLAN performance, but most of them focused only on single WLAN environments without accounting for inter-cell contention. The de facto QoS-provisioning mechanism for WLANs, i.e., the Enhanced Distributed Channel Access (EDCA), is no exception to this. The EDCA focuses only on inter-flow priority distinction and has not considered the effect of inter-cell contention which significantly restricts its efficiency. This paper presents an enhanced QoS provisioning framework that takes into account inter-cell level differentiation as well as inter-flow level priority, which may be viewed as extension of QoS provisioning from a single-WLAN domain to a multi-WLAN domain. We also propose an architecture for managing multi-AP systems in which a central controller regulates the wireless channel occupancy of APs by adaptively configuring the cell-level QoS parameters. Our extensive simulation results show that the proposed inter-AP cooperative QoS scheme overcomes the limit of legacy 802.11e and provides a high level of fairness in large-scale densely-deployed WLANs.     

QoS provisioning for multimedia wireless networks

As we move towards IP-based multimedia wireless networks with voice, video and data convergence, quality of service (QoS) provisioning will become an increasingly challenging task. One implication is that greater emphasis on managing the call admission and overall network resources will be needed. This paper presents a conservative and adaptive quality of service (CAQoS) framework for provisioning the QoS for both real-time and non-real-time traffic in a multimedia wireless network. Unlike most conventional schemes, which gradually scale down the bandwidth of ongoing connections to accommodate new connection/hand-off requests, CAQoS introduces an early scaling-down of bandwidth for new connections based on a designated provisioning model. The performance of a CAQoS system is evaluated through simulations of a realistic wireless environment. Simulation results show that CAQoS meets our design goals and outperforms conventional schemes.     

QoS provisioning dynamic connection-admission control for multimedia wireless networks using a Hopfield neural network

This paper presents a quality-of-service (QoS) provisioning dynamic connection-admission control (CAC) algorithm for multimedia wireless networks. A multimedia connection consists of several substreams (i.e., service classes), each of which presets a range of feasible QoS levels (e.g., data rates). The proposed algorithm is mainly devoted to finding the best possible QoS levels for all the connections (i.e., QoS vector) that maximize resource utilization by fairly distributing wireless resources among the connections while maximizing the statistical multiplexing gain (i.e., minimizing the blocking and dropping probabilities). In the case of congestion (overload), the algorithm uniformly degrades the QoS levels of the existing connections (but only slightly) in order to spare some resources for serving new or handoff connections, thereby naturally minimizing the blocking and dropping probabilities (it amounts to maximizing the statistical multiplexing gain). The algorithm employs a Hopfield neural network (HNN) for finding a QoS vector. The problem itself is formulated as a multi-objective optimization problem. Hardware-based HNN exhibits high (computational) speed that permits real time running of the CAC algorithm. Simulation results show that the algorithm can maximize resource utilization and maintain fairness in resource sharing, while maximizing the statistical multiplexing gain in providing acceptable service grades. Furthermore, the results are relatively insensitive to handoff rates.     

End-to-end QoS provisioning in mobile heterogeneous networks

The remarkable advances in information technologies bring a heterogeneous environment for mobile users and service providers. This heterogeneity exists in wireless access technologies, networks, user terminals, applications, service providers, and so on. The ability to provide seamless and adaptive quality of service in such a heterogeneous environment is key to the success of next-generation wireless communications systems. There has been a considerable amount of QoS research recently. However, the main part of this research has been in the context of individual architectural components, and much less progress has been made in addressing the issue of an overall QoS architecture for the mobile Internet. This article first summarizes the state-of-the-art QoS techniques and standardization activities, then examines in detail important challenges in building a ubiquitous QoS framework over the heterogeneous environment, and finally proposes a QoS framework integrating a three-plane network infrastructure and a unified terminal cross-layer adaptation platform to provide seamless support for future applications.     

基于神经网络的无线网络故障节点定位技术

传统无线网络故障节点定位方法无法有效处理节点功率波动以及模糊环境对故障节点定位精度的干扰。提出基于小波神经网络的无线网络故障节点定位方法,分析了小波神经网络在节点故障定位的三种作用形式,融合形式1和3对冗余节点故障进行定位,将小波神经网络当成预测器,将前一采样时刻的正常输出交叉输入n个小波神经网络,获取节点当前时刻的预测输出值,取节点预测输出值和真实输出值的残差,若该残差值高于阈值,则说明该节点是故障节点。实验结果表明,所提故障节点定位方法能够对节点的附加、倍数以及短路故障进行准确定位。     

QoS provisioning and tracking fluid policies in input queueingswitches

The concept of tracking fluid policies by packetized policies is extended to input queueing switches. It is considered that the speedup of the switch is one. One of the interesting applications of the tracking policy in TDMA satellite switches is elaborated. For the special case of 2×2 switches, it is shown that a tracking nonanticipative policy always exists. It is found that, in general, nonanticipative policies do not exist for switches with more than two input and output ports. For the general case of N×N switches, a heuristic tracking policy is provided. The heuristic algorithm is based on two notions: port tracking and critical links. These notions can be employed in the derivation of other heuristic tracking policies as well. Simulation results show the usefulness of the heuristic algorithm and the two basic concepts it relies on     

Predictive mobility support for QoS provisioning in mobile wirelessenvironments

With the proliferation of wireless network technologies, mobile users are expected to demand the same quality of service (QoS) available to fixed users. This paper presents a predictive and adaptive scheme to support timed-QoS guarantees in pico- and micro-cellular environments. The proposed scheme integrates the mobility model into the service model to achieve efficient network resource utilization and avoid severe network congestion. The mobility model uses a probabilistic approach to determine the most likely cluster to be visited by the mobile unit. The admission control is invoked when a new call arrives or an existing call performs a handoff to verify the feasibility of supporting the call. The performance of the proposed schemes is compared to the shadow cluster scheme. The performance of the proposed scheme under different traffic patterns is also presented     

Diffserv extensions for QoS provisioning in IP mobility environments

We focus on DiffServ for QoS provisioning in radio access networks (RANs). We first give short explanations of the DiffServ model. We then investigate the problems of DiffServ under IP mobility environments. We also present several DiffServ proposals in IP-based access networks. We finally propose a mobility-aware drop precedence scheme for flows experiencing handover events.     

分簇无线多媒体传感器网络服务质量研究

如何为多媒体数据流提供有保障的服务质量是研究的重要问题。文中提出了一种适用于无线多媒体传感器网络的分簇方法和判断路径流量是否过载的方法,采用两跳向前检测节点的流量,确保路径的空闲,为多媒体数据流提供时延保障服务。与LEACH协议相比,文中方法更有利于网络能耗均衡化,降低了网络拥塞的可能性,具有更好的传输实时性。文中建立了数据模型,对时延进行了分析。仿真结果表明文中方法有更长的网络生存期和更少的数据溢出。     

基于内网节点的防火墙穿透方法

网络防火墙是保护数据安全的有效手段,目前采用最多的是NAT技术,但在特定情况下需要外网无痕穿越防火墙对内网数据进行访问,在这种需求下NAT技术就束手无策。针对上述需求,提出一种新的防火墙穿透技术,采用内网节点主动发起连接的方式连接内外网,实现防火墙或子网的穿透,并在ARM平台上实验验证了该技术的可行性,该方法已经获得了国家知识产权局的发明专利授权。     

On-line provisioning of network services

The authors review the telecommunications service-provisioning process. They describe a view of future service provisioning and discuss the issues and technical problems involved in online service provisioning. They explore how intelligent network elements in conjunction with distributed algorithms and distributed databases can be used to achieve this objective. The authors also present and describe a system architecture for the implementation of online service provisioning     

End-to-end QoS provisioning in 4G with mobile hotspots

The novel concept of mobile hotspots, characterized by a group of wireless users equipped with wireless LAN cards, moving as a whole and requiring Internet connectivity, is gaining the interest of the telecommunications research community. This article intends to contribute to this research topic by proposing alternative solutions for the deployment of a mobile gateway device offering 3G connectivity to the group of WLAN users while they are moving. This is a decisive aspect of the 3G migration to 4G networks. The proposed solutions allow for two-hop wireless paths between WLAN and 3G systems, and performing control over-high layer issues, specifically focusing on end-to-end QoS provisioning. The pros and cons of envisaged design solutions are addressed and their relevance justified considering purposes, target users, and applications.     

Ad hoc网络中基于数据流的QoS路由协议

已有ad hoc网络中的QoS路由都是基于目的地址的选路并预留资源,当源节点针对同一个目的节点先后建立两个或者多个实时业务流的时候,将导致几个数据流争用资源,使得几个流的QoS都无法得到保证。针对这个问题,文章提出了基于流的QoS路由机制,并且进行了仿真分析,仿真结果表明这种机制能够解决这个问题,使QoS得到保证。     

QoS provisioning in micro-cellular networks supporting multiple classes of traffic

We introduce an adaptive call admission control mechanism for wireless/mobile networks supporting multiple classes of traffic, and discuss a number of resource sharing schemes which can be used to allocate wireless bandwidth to different classes of traffic. The adaptive call admission control reacts to changing new call arrival rates, and the resource sharing mechanism reacts to rapidly changing traffic conditions in every radio cell due to mobility of mobile users. In addition, we have provided an analytical methodology which shows that the combination of the call admission control and the resource sharing schemes guarantees a predefined quality-of-service to each class of traffic. One major advantage of our approach is that it can be performed in a distributed fashion removing any bottlenecks that might arise due to frequent invocation of network call control functions.     

A novel monitoring architecture for media services adaptation based on network QoS to perceived QoS mapping

One of the future visions of multimedia networking is the provision of multimedia content at a variety of quality and price levels. Of the many approaches to this issue, one of the most predominant techniques is the concept of Perceived Quality of Service (PQoS), which extends the traditional engineering-based QoS concept to the perceptual satisfaction that the user receives from the reception of multimedia content. In this context, PQoS monitoring is becoming crucial to media service providers (SPs) for providing not only quantified PQoS-based services, but also service assurance based on multimedia content adaptation across heterogeneous networks. This work proposes a novel cross-layer monitoring architecture that utilizes a new Network QoS (NQoS) to PQoS mapping framework at the application level. The resulting QoS monitoring should allow the content delivery system to take sophisticated actions for real time media content adaptation, and aims to provide perceived service performance verification with respect to the QoS guarantees that have been specified in contractual agreements between providers and end-users. A subsequent performance evaluation of the proposed model conducted using a real test-bed environment demonstrates both the accuracy and feasibility of the network level measurements, the NQoS to PQoS mapping and the overall feasibility of the proposed end-to-end monitoring solution. This work is partially funded by European Commission (ENTHRONE EU project IST 507637). See . The authors would like to thank ENTHRONE EU project partners for their inputs and valuable discussions.     

基于网络演算的无线自组网QoS性能确定上界研究

为保证无线自组网的服务质量(QoS),需精确求解其性能确定上界.对进入无线自组网节点的数据流进行漏桶管制,节点为数据流提供基于速率-延迟(rate-latency)模型的服务保障,在已有无线自组网链路吞吐量模型的基础上利用网络演算理论推导了无线自组网节点的积压数据上界、端到端数据流的延迟上界以及端到端数据流的延迟抖动上界模型.对网格形式拓扑的无线自组网,不同数据流的仿真结果都在数值计算的上界范围之内,表明基于网络演算理论的无线自组网的QoS性能上界模型具有较好的性能.     

基于无线网络动态容量分析的延时QoS研究

本文提出了基于信道动态容量分析数据包延迟超限率的方法,依据对信源队列分析和衰落信道动态容量计算,研究了基于延时的QoS保障仿真模型,并仿真了恒定速率视频业务在Rayleigh信道下数据包传输延迟特性.仿真结果表明,在有多普勒频率的时变衰落信道下,提出的方法能够有效估计数据传输的延迟超限率,为实时业务在时变衰落信道下的延...