Mobility in wireless networks

Ohne Zusammenfassung     

QoS control in wireless ATM

This paper introduces a 3-level multiagent architecture for QoS control in WATM. The ultimate aim of the proposed architecture is to provide a self-regulating network congestion control management by means of global network state awareness and agent interactions. The agents dynamically manage the buffer space at the level of a switch and interact to reduce the cell loss ratio while guaranteeing a bounded transit delay. We particularly address video transmission over UBR services using a per-VP queuing approach and an adaptive cell discarding congestion control scheme. Furthermore, a dynamic reconfiguration of the agents is performed during handoffs in order to continue meeting user end-to-end QoS requirements. The handoff delay absorption is also addressed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Mobility and QoS Support in Mobile IP Networks

1　IntroductionAnall IP basedmobilenetworksuchas 4G ,whoseaccessandcorenetworksarebasedonIP ,hasintrinsicadvantagesoverits predecessors.Forstarters ,IPiscompatiblewith ,andindependentof,theactualradioaccesstechnology .WithIP ,onecanbasicallygetridofthelock inbetweenthecorenet workprotocol,thelinklayerandtheradioaccessprotocol.IPtoleratesavarietyofradioaccessproto cols.Itsupportsthedesignofacorenetworkthatgivescompleteflexibilitynomatterwhattheradioaccessnetworkis.Onecouldbeacorenetworkpro…     

Mobility support in wireless Internet

The tremendous advancement and popularity of wireless access technologies necessitates the convergence of multimedia (audio, video, and text) services on a unified global (seamless) network infrastructure. Circuit-switched proprietary telecommunication networks are evolving toward more cost-effective and uniform packet-switched networks such as those based on IP. However, one of the key challenges for the deployment of such wireless Internet infrastructure is to efficiently manage user mobility. To provide seamless services to mobile users, several protocols have been proposed over the years targeting different layers in the network protocol stack. In this article we present a cross-layer perspective on the mobility protocols by identifying the key features of their design principles and performance issues. An analysis of the signaling overhead and handoff delay for some representative protocols in each layer is also presented. Our conclusion is that although the application layer protocol is worse than the protocols operating in the lower layers, in terms of handoff delay and signaling overhead, it is better suited as a potential mobility solution for the next-generation heterogeneous networks, if we consider such factors as protocol stack modification, infrastructure change, and inherent operational complexity.     

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.     

Handling Mobility Management and QoS Aspects in All-IP Networks

It is well-known that all-IP networks will be more dynamic and should be more flexible than current networks. Deploying these networks requires, however, overcoming many challenges. One of the main challenges is how to provide Quality of Service (QoS) guarantees in such highly dynamic mobile environments. Addressing this challenge is the main focus of this paper, which provides an insight into how mobility management and QoS solutions can be coupled with each other. Moreover, the paper describes in detail the QoS-aware Mobile IP Fast Authentication Protocol (QoMIFA), which is capable of handling mobility management and simultaneously reserving resources, thus, satisfying the requirements of all-IP mobile communication networks. The paper evaluates also the performance of QoMIFA compared to the well-known Simple QoS signaling protocol (Simple QoS) by means of simulation studies modeled in the network simulator 2 (ns2). The evaluation comprises the investigation of the impact of the network load on both protocols. Our simulation results show that QoMIFA is capable of achieving fast and smooth handoffs in addition to its capability of reserving resources very quickly. With respect to the time required to reserve resources for uplink traffic, QoMIFA is up to 80% faster than Simple QoS. If the resources are reserved for downlink traffic, QoMIFA performs up to 93% better. Considering the number of dropped packets per handoff, QoMIFA reduces the packets lost per handoff by 22% up to 76% on uplink and by 55% up to 93% on downlink as compared to Simple QoS. A main advantage of QoMIFA is that it minimizes the packets sent as best-effort (without QoS guarantees) after handoffs. QoMIFA reduces the best-effort packets transmitted on downlink by approximately 94% compared to Simple QoS and eliminates these packets on uplink.     

Mobility management in next-generation wireless systems

This paper describes current and proposed protocols for mobility management for public land mobile network (PLMN)-based networks, mobile Internet protocol (IP) wireless asynchronous transfer mode (ATM) and satellite networks. The integration of these networks will be discussed in the context of the next evolutionary step of wireless communication networks. First, a review is provided of location management algorithms for personal communication systems (PCS) implemented over a PLMN network. The latest protocol changes for location registration and handoff are investigated for mobile IP followed by a discussion of proposed protocols for wireless ATM and satellite networks. Finally, an outline of open problems to be addressed by the next generation of wireless network service is discussed     

Mobility management in wireless ATM networks

Mobile ATM offers a common wired network infrastructure to support mobility of wireless terminals, independent of the wireless access protocol. In addition, it allows seamless migration to future wireless broadband services, such as wireless ATM, by enabling mobility of end-to-end ATM connections. In spite of the diversity in mobile networking technologies (e.g., cellular telephony, mobile-IP, packet data services, PCS), all of them require two fundamental mechanisms: location management and handoff. This article describes different schemes for augmenting a wired ATM network to support location management of mobile terminals and handoff protocols for rerouting a connection data path when the endpoint moves. A prototype implementation of mobile ATM integrating mobility support with ATM signaling and connection setup, is presented. It shows how mobile ATM may be used to provide mobility support to an IP terminal using non-ATM wireless access     

Mobility management in heterogeneous wireless networks

In heterogeneous wireless networks, mobile users are able to move from their home networks to different foreign networks while maintaining access capability to their subscribed services, which refers to global mobility. One of the key challenges in global mobility management is intersystem location management, which consists of keeping track of mobile users who roam into foreign networks. This paper presents an overview of mobility management in heterogeneous wireless networks and introduces a scheme which improves location management efficiency in terms of total signaling costs and intersystem paging delay. More specifically, cost reduction reaches about 50% when comparing the proposed architecture with conventional architectures.     

Mobility patterns in microcellular wireless networks

This study investigates mobility patterns in microcellular wireless networks, based on measurements from the 802.11 based system that blankets the Carnegie Mellon University campus. We characterize the distribution of dwell time, which is the length of time that a mobile device remains in a cell until the next handoff, and sign-on interarrival time, which is the length of time between successive sign-ons from the same mobile device. Many researchers have assumed that these distributions are exponential, but our results based on empirical analysis show that dwell time and sign-on interarrival time can be accurately described using heavy-tailed arithmetic distributions that have infinite mean and variance. We also show that the number of handoffs per sign-on can be modeled accurately with a heavy-tailed distribution.     

QoS issues in ad hoc wireless networks

Ad hoc wireless networks consist of mobile nodes interconnected by multihop communication paths. Unlike conventional wireless networks, ad hoc networks have no fixed network infrastructure or administrative support. The topology of the network changes dynamically as mobile nodes join or depart the network or radio links between nodes become unusable. This article addresses some of the quality of service issues for ad hoc networks which have started to receive increasing attention in the literature. The focus is on QoS routing. This is a complex and difficult issue because of the dynamic nature of the network topology and generally imprecise network state information. We present the basic concepts and discuss some of the results. The article concludes with some observations on the open areas for further investigation     

Adaptive QoS scheduling in wireless cellular networks

Quality of service (QoS) has been always controversial in resource shared networks. Scheduling as a packet prioritizing mechanism at Data Link Layer (DLL) contributes to QoS guarantee provisioning significantly. In this paper, a novel packet scheduler is developed in wireless cellular networks. The proposed scheme provides QoS-guaranteed service for the applications running on the sensor nodes in all the three aspects of QoS, i.e. data rate, packet loss and packet delay with regard to jitter simultaneously. We establish a three-dimensional space with certain basis vectors for QoS and introduce the efficient point of performance in terms of QoS provisioning in that space. Then we develop a generalized metric, the QoS-deviation, which is the Euclidean distance between the QoS work point of flows and the QoS efficient point in the proposed space. Based on this metric, a novel scheduling approach, namely AQDC, is designed which makes it possible to tune the trade-off between QoS provisioning and throughput optimization in an adaptive manner depending on the current Cell QoS-deviation level (CDL). Furthermore, we also develop another scheduler, namely ARTC, which is the residual-time version of the AQDC scheduler. Finally, a QoS-deviation-based CAC policy will be introduced which can be applied to all schedulers without any consideration about their structure and can be employed in cellular packet switched networks.     

QoS routing in ad hoc wireless networks

The emergence of nomadic applications have generated much interest in wireless network infrastructures that support real-time communications. We propose a bandwidth routing protocol for quality-of-service (QoS) support in a multihop mobile network. The QoS routing feature is important for a mobile network to interconnect wired networks with QoS support (e.g., ATM, Internet, etc.). The QoS routing protocol can also work in a stand-alone multihop mobile network for real-time applications. This QoS routing protocol contains end-to-end bandwidth calculation and bandwidth allocation. Under such a routing protocol, the source (or the ATM gateway) is informed of the bandwidth and QoS available to any destination in the mobile network. This knowledge enables the establishment of QoS connections within the mobile network and the efficient support of real-time applications. In addition, it enables more efficient call admission control. In the case of ATM interconnection, the bandwidth information can be used to carry out intelligent handoff between ATM gateways and/or to extend the ATM virtual circuit (VC) service to the mobile network with possible renegotiation of QoS parameters at the gateway. We examine the system performance in various QoS traffic flows and mobility environments via simulation. Simulation results suggest distinct performance advantages of our protocol that calculates the bandwidth information. It is particularly useful in call admission control. Furthermore, “standby” routing enhances the performance in the mobile environment. Simulation experiments show this improvement     

QoS routing for wireless ad hoc networks: problems, algorithms, and protocols

QoS routing plays an important role for providing QoS in wireless ad hoc networks. The goals of QoS routing are in general twofold: selecting routes with satisfied QoS requirement(s), and achieving global efficiency in resource utilization. In this article we first discuss some key design considerations in providing QoS routing support, and present a review of previous work addressing the issue of route selection subject to QoS constraint(s). We then devise an on-demand delay-constrained unicast routing protocol. Various strategies are employed in the protocol to reduce the communication overhead in acquiring cost-effective delay-constrained routes. Simulation results are used to verify our expectation of the high performance of the devised protocol. Finally, we discuss some possible future directions for providing efficient QoS routing support in wireless ad hoc networks.     

Mobility support for IP over wireless ATM

A wireless ATM system consists of a core network infrastructure that provides mobility support to end terminals and a wireless access link. This article outlines two schemes for supporting mobility of IP terminals in this network. In the first scheme, location management and handoff support is integrated within the ATM signaling and control framework (“mobile ATM”), and mobility is transparently supported at the IP layer by mobile ATM underneath. In the second approach, the IP protocol stack is directly executed on ATM switches (without an intermediate ATM signaling stack) using an IP switching technique called IPSOFACTO (IP Switching Over Fast ATM Cell Transport), and terminal mobility is supported via mobile IP     

无线局域网MAC层QoS研究

在分析无线网协议提供QoS保证方面存在的问题的基础上，讨论了IEEE802．11e的两个新的策略：增强的分布式协调功能和混合协调功能。通过对受控竞争机制的分析．指出了IEEE802．11e仍存在的不足及未来的发展方向。     

Mobility prediction and routing in ad hoc wireless networks

By exploiting non-random behaviors for the mobility patterns that mobile users exhibit, we can predict the future state of network topology and perform route reconstruction proactively in a timely manner. Moreover, by using the predicted information on the network topology, we can eliminate transmissions of control packets otherwise needed to reconstruct the route and thus reduce overhead. In this paper, we propose various schemes to improve routing protocol performances by using mobility prediction. We then evaluate the effectiveness of using mobility prediction via simulation. Copyright © 2001 John Wiley & Sons, Ltd.     

Mobility management and control protocol for wireless ATM networks

The introduction of wireless ATM (WATM) in customer premises network environments necessitates the design of mobility protocols, since the existing versions of B-ISDN signaling do not support terminal mobility. Such protocols can be deployed either as extensions to the standard signaling capabilities, or as individual solutions that have little or no impact on existing infrastructures (switches, signaling software, etc.). A WATM architecture that adopts the latter approach is presented. After a discussion of the problems encountered in the integration of wireless networking and B-ISDN ATM technologies, a mobility management and control (MMC) protocol is proposed. Finally, in the framework of the proposed MMC protocol, algorithms for implementing mobility procedures (handover and registration) are described