Resource management for QoS support in cellular/WLAN interworking

To provide mobile users with seamless Internet access anywhere and anytime/ there is a strong demand for interworking mechanisms between cellular networks and wireless local area networks in the next-generation all-IP wireless networks. In this article we focus on resource management and call admission control for QoS support in cellular/WLAN interworking. In specific, a DiffServ interworking architecture with loose coupling is presented. Resource allocation in the interworking environment is investigated/ taking into account the network characteristics, vertical handoff, user mobility, and service types. An effective call admission control strategy with service differentiation is proposed for QoS provisioning and efficient resource utilization. Numerical results demonstrate the effectiveness of the proposed call admission control scheme.     

Completing the convergence puzzle: a survey and a roadmap

Convergence has more than ever been a central issue for fixed and mobile operators throughout the world and is considered to be the next big step in the evolution of telecommunication networks. Convergence opens new market opportunities and competition among network operators and above all offers enhanced user experience. Multimode handsets and the proliferation of terminals and access technologies are generating increasing demands for solutions that enable convergence, seamless handover, and transparent service delivery across heterogeneous access networks. Different strategies are available for operators, depending on the services they intend to deliver to their customers, from basic commercial convergence limited to unified billing for Fixed/Mobile/Internet up to in-dept network convergence covering new applications and services. This article surveys different technologies which offer seamless handover and converged access to mobile voice, video, and data services. It provides first the different network parts involved in defining the operator global convergence strategy and then surveys different technologies which achieve this step-by-step convergence. We present the main features of these technologies and discuss their limitations and potentials to enable convergence in heterogeneous networks. We also provide a personal stance as to the emergence of these technologies and our vision towards the long term converged telecommunication networks.     

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.     

Unified Mobility Manager: enabling efficient SIP/UMTS mobile network control

Internet telephony is viewed as an emerging technology not only for wireline networks, but also for third-generation wireless networks. Although IP end to end is considered the ultimate approach to future wireless voice services, there is still a long way to go before IP voice packets can be effectively transported over the air. Therefore, Internet telephony and today's circuit-switched wireless network will coexist for years to come, and it is essential to effectively perform interworking between these networks. This article proposes the Unified Mobility Manager (UMM) that achieves efficient interworking between traditional wireless networks and Internet telephony networks. The main characteristic of the UMM is that it combines UMTS HLR and SIP proxy functionality in one logical entity, which helps eliminate the performance degradation due to interworking between SIP and UMTS. This article identifies seven potential network architectures with and without the UMM and with varying degrees of IP penetration in the wireless core networks, and performs comparative analysis in terms of their call setup signaling latency. Our performance results show that for SIP originated calls, the architecture with the UMM can achieve better performance than existing UMTS networks without the UMM. Our results further show that when the backbone network is fully IP-enabled, dramatic performance gains can be accomplished with the UMM for PSTN originated calls as well as for SIP originated calls. The article also demonstrates that the UMM allows graceful migration from today's circuit-switched wireless networks to hybrid SIP/circuit-switched wireless networks, and toward the IMS architecture for all-IP UMTS networks in the future.     

Seamless IP mobility support for flat architecture mobile WiMAX networks - [WiMAX update]

The growing demand for wireless Internet services is accelerating the evolution of wireless networks toward all-IP architecture, and the mobile WiMAX network is a prominent example. Although currently deployed mobile WiMAX networks use hierarchical architecture, flat architecture is feasible and specified as a design alternative in the mobile WiMAX standard. In flat architecture the functionalities of the ASN-GW and BS are consolidated into a single element. In this article we first discuss the benefits and challenges of flat architecture mobile WiMAX networks. We then present a scheme to deal with the seamless mobility issue, which is one of the key challenges of the flat architecture. The proposed scheme combines two standard IP-mobility protocols, Proxy Mobile IP and Fast Mobile IP, and customizes them for IEEE 802.16e-based mobile WiMAX networks. This provides interoperability with existing mobile WiMAX networks. We demonstrate the viability of the proposed scheme through simulations using NS-2.     

Global roaming in next-generation networks

Next-generation mobile/wireless networks are already under preliminary deployment. Mobile/wireless all-IP networks are expected to provide a substantially wider and enhanced range of services. However, an evolutionary rather than revolutionary approach to the deployment of a global all-IP wireless/mobile network is expected. To support global roaming, next-generation networks will require the integration and interoperation of mobility management processes under a worldwide wireless communications infrastructure. In this article global roaming is addressed as one of the main issues of next-generation mobile networks. Apart from the physical layer connectivity and radio spectrum allocation plans, mobility in a hierarchical structured scheme is discussed. An all-IP wireless/mobile network combined with inherited mobility schemes of each network layer and Mobile IP extensions is proposed. In this respect the mobility management mechanisms in WLAN, cellular, and satellite networks are analyzed, and an all-IP architecture is described and an enhanced roaming scenario presented     

Mobility management in third-generation all-IP networks

It is now widely recognized that using IP as the foundation for next-generation mobile networks makes strong economic and technical sense, since it takes advantage of the ubiquitous installed IP infrastructure, capitalizes on the IETF standardization process, and benefits from both existing and emerging IP-related technologies and services. The large-scale support of data services and their integration with legacy services are the common objectives of all wireless efforts termed third generation (3G) and beyond. In these all-IP wireless networks, IP can be deployed in two modes: the transport mode and the native mode. As we show in this article, this duality in the use of IP has a significant impact on network efficiency and performance. It is the extended native use of IP in the terrestrial segment of a wireless operator's domain that more readily allows for building a converged network with multiple access technologies. We then discuss the different levels of mobility in the all-IP network. In particular, our focus is on micromobility, and on the issue of seamless localized mobility within the converged network. After reviewing the mobility schemes that have emerged in previous years, we describe a hierarchical mobility management scheme based on multiprotocol label switching (MPLS). The scheme employs an enhanced type of MPLS routers, called label edge mobility agents, and is scalable, efficient, and flexible. It directly inherits the noted capabilities of MPLS in terms of support of QoS, traffic engineering, advanced IP services, and fast restoration. This scheme does not use nodes that are specific to any given wireless technology, and is well suited for gradual deployment     

Overview of mobile WiMAX technology and evolution

Mobile WiMAX is a fast growing broadband access technology that enables low-cost mobile Internet applications, and realizes the convergence of mobile and fixed broadband access in a single air interface and network architecture. Mobile WiMAX combines OFDMA and advanced MIMO schemes along with flexible bandwidth and fast link adaptation, creating a highly efficient air interface that exceeds the capacity of existing and evolving 3G radio access networks. WiMAX networks, built on all-IP network architecture for plug and play network deployments, can support a mix of different usage and service models. While some consider mobile WiMAX as a candidate for the fourth generation of mobile networks, others view it as the first generation of mobile Internet technologies emerging from a wider ecosystem targeting to extend the success of WiFi over wide area networks supporting mobility. This article provides a high-level overview of mobile WiMAX technology and its evolution roadmap from both radio and network perspectives.     

SIP Multicast-Based Mobile Quality-of-Service Support over Heterogeneous IP Multimedia Subsystems

The Universal Mobile Telecommunications System (UMTS) all-IP network supports IP multimedia services through the IP Multimedia Subsystem (IMS). This paper proposes a mobile Quality-of-Service (QoS) framework for heterogeneous IMS interworking. To reduce the handoff disruption time, this framework supports the IMS mobility based on the concept of Session Initiation Protocol (SIP) multicast. In our approach, the mobility of a User Equipment (UE) is modeled as a transition in the multicast group membership. With the concept of dynamic shifting of the multicast group's members, the flow of actual data packets can be switched to the new route as quickly as possible. To overcome mobility impact on service guarantees, UEs need to make QoS resource reservations in advance at neighboring IMS networks, where they may visit during the lifetime of the ongoing sessions. These locations become the leaves of the multicast tree in our approach. To obtain more efficient use of the scarce wireless bandwidth, our approach allows UEs to temporarily exploit the inactive bandwidths reserved by other UEs in the current IMS/access network. Analytic and simulation models are developed to investigate our resource reservation scheme. The results indicate that our scheme yields comparable performance to that of the previously proposed channel assignment schemes.     

3G UMTS中的IP多媒体子系统探析

下一代的移动通信系统将基于全IP的网络构架,提供开放的业务生成环境。3GPP在其UMTSR5版本中首次引入了IP多媒体子系统(IMS)的概念,作为下一代网络的重要平台,IMS不仅实现了固网与移动网业务的无缝融合,还有利于运营商快速、灵活地开发更加丰富多彩的移动多媒体业务,从而吸引大量的终端用户。文章在描述IMS体系结构的基础上,特别针对IMS中几个关键要素点进行了重点分析。     

Seamless integration of mobile WiMAX in 3GPP networks

As the wireless industry makes its way to the next generation of mobile systems, it is important to engineer solutions that enable seamless integration of emerging 4G access technologies within the currently deployed and/or evolved 2G/3G infrastructures. In this article we address a specific case of such a seamless integration, that of mobile WiMAX in evolved 3GPP networks. In this context we investigate the architecture and the key procedures that enable this integration, and we also introduce a novel handover mechanism that enables seamless mobility between mobile WiMAX and legacy 3GPP access, such as UTRAN or GERAN. The core characteristic of this novel handover mechanism is that mobile terminals do not need to support simultaneous transmission on both WiMAX and 3GPP accesses; therefore, it mitigates the RF coexistence issues that exist otherwise and improves handover performance. In addition, we provide a brief overview of mobile WiMAX and the evolved 3GPP network technologies, and we set the appropriate background material before presenting our proposed handover mechanism. Our main conclusion is that integrating mobile WiMAX in evolved 3GPP networks is a compelling approach for providing wireless broadband services, and mobility across WiMAX and 3GPP access can become seamless and efficient with no need for mobile terminals to support simultaneous transmission on both types of access.     

A self-adaptive service provisioning framework for 3G+/4G mobile applications

In light of the increasing acceptance of the notion of next generation networks (NGN), which results from the convergence of the fixed and mobile telecommunications, Internet, and entertainment sectors, there is a need for the realization of next-generation service delivery platforms to allow seamless and adaptive provisioning of multimedia information and communication services to mobile users. This means that in such an NGN environment different end systems, access networks, and service platforms have to be integrated. For this highly heterogeneous communications and services environment, we propose a self-adaptive service provisioning middleware framework (ASPF), which, by interoperating with existing wireless and wireline service delivery platforms, aims to enable seamless omnipresent service provisioning to mobile users anywhere, anytime, and in any context. The ASPF is intended to "liberate" applications from space and time limitations, networks, platforms, and device dependences, minimize time-to-market constraints, and eliminate major hurdles that hinder the rapid deployment of new mobile services and applications. Key to this goal is interworking/integration with current SDPs, such as IN/CAMEL, OSA/Parlay, and the emerging IMS.     

Fast Handoff in SIP-Based Next Generation Mobile Networks

It is commonly held that next generation mobile systems will be developed on the Internet in combination with diverse access technologies, as the future network architecture will be the coming together of various overlapping wireless access networks. Integrating various wireless networks in future heterogeneous networking environments poses many difficulties, the most critical challenge of which is efficient support for seamless mobility. SIP is a promising nominee for managing mobility in heterogeneous networks as it provides mobility within the application layer and the characteristics of the lower layer protocols are invisible to it. However, the performance of SIP-based mobility management is downgraded, resulting from its adoption of TCP/UDP for signaling and its strict separation between the lower layers and the application layer of the protocol stack. In this paper, a SIP-based cross-layer design for fast handoffs is proposed to shorten the service interruption time when a mobile node crosses the overlapped area of a WLAN/3G cellular system. As will be shown by the simulation results, the SIP-based solution proposed in this paper effectively lessens the handoff delays caused by either the horizontal handoff or vertical handoff in future all-IP heterogeneous wireless networks.     

基于IPv6的快速切换改进方案

在移动IP网络中,当前的移动性管理方案由于其基本协议的切换时延较大、丢包率较高而不能适应实时业务和移动通信的要求,所以需要改善移动性管理策略的切换性能,尽量实现无缝切换和零丢包率。提出了一种基于移动IPv6的快速切换的改进方案,采用一种新的地址分配方式使得移动节点能够在移动至新的网络后迅速获取新的转交地址,有效地减少了切换所产生的时延和丢包率,具有较好的切换性能。     

A mobility toolbox architecture for all-IP networks: an ambient networks approach [architectures and protocols for mobility management in all-IP mobile networks]

The future Internet will need to cater to an increasing number of mobile devices and mobile networks, roaming across different access networks and trust domains. In addition, various limitations imposed by the end user, service provider, or network operator agreements and preferences will need to be considered. A plethora of mobility management protocols have been proposed to handle different and mostly limited sets of these mobility requirements. In this article we make the case for coexistence of mobility protocols in order to support the large range of mobility scenarios possible in future all-IP networks. This coexistence takes the form of a mobility toolbox that enables mobility handling mechanisms to be selected according to the context. We then present a design for the mobility toolbox as a component of the ambient networks architecture, including a simplified mobility tool interface toward protocol modules, and show how it meets the requirements of future all-IP networks. We further demonstrate the feasibility and performance gains of the mobility toolbox architecture with a prototype implementation based on network mobility.     

Enabling Heterogeneous Mobility in Android Devices

The fast growing of mobile Internet users with the ability of using a wide diversity of access technologies such as Wi-Fi, WiMAX and UMTS/LTE, and the increasing proliferation of mobile devices with heterogeneous network interfaces, require versatile mobility mechanisms providing seamless roaming across those access technologies. Mobility agents such as Mobile IP and Fast MIPv6 are common, however, these solutions still have limitations when dealing with multiple link-layer technologies. In this context, the emerging standard IEEE 802.21 provides a framework which enables mobile agents and network operators to improve the handover process in heterogeneous networks. In this context, this paper presents and discusses the design and implementation of a mobility-aware solution for an Android device, using the IEEE 802.21 framework. A modified Android user terminal is proposed to improve the handover process, assuming a make-before-break approach. Resorting to an experimental testbed, the obtained results show that the proposed solution is an effective contribution to successfully accomplish seamless mobility of Android-based devices operating in 3G and Wi-Fi networks.     

Design and implementation of a WLAN/cdma2000 interworking architecture

The combination of 3G and WLAN wireless technologies offers the possibility of achieving anywhere, anytime Internet access, bringing benefits to both end users and service providers. We discuss interworking architectures for providing integrated service capability across widely deployed 3G cdma2000-based and IEEE 802.11-based networks. Specifically, we present two design choices for integration: tightly coupled and loosely coupled, and recommend the latter as a preferred option. We describe in detail the implementation of a loosely coupled integrated network which provides two kinds of roaming services, a SimpleIP service and a Mobile-IP service. We present, in detail, two new components used to build these services: a network element called a WLAN integration gateway deployed in WLAN networks; a client software on the mobile device. For a mobile device with interfaces to both technologies, our system supports seamless handoff in the presence of overlapping radio coverage.     

Service Oriented Testbed Infrastructures: a Cross-Layer Approach for NGNs

Existing telecommunications networks and classical roles of operators are subject to fundamental change. Core network technologies have been re-defined under the label of Next Generation Networks (NGN) and the transition from existing legacy infrastructures towards an all-IP based NGN is ongoing. Following this paradigm shift within telecommunications, new approaches in services and service composition are currently explored for converging network domains to support legacy circuit-switched networks, NGNs, and integration with the World Wide Web (WWW). Furthermore, emerging initiatives as the Japanese Architecture Design Project for New Generation Network (AKARI), U.S.-based Global Environment for Network Innovations (GENI), Germany Laboratories (G-Lab), and the European Future Internet Research & Experimentation (FIRE) envision a Future Internet allowing automatic cross-layer network adaptation on a service-specific basis. In this report, we describe our setup of a service-oriented research facility for services on top of converging networks as a starting point for service composition in inter-domain, federated testbed environments to allow cross layer service and network composition.     

A framework for seamless roaming across cellular and wireless local area networks

In the future, wireless and mobile users will have increased demands for seamless roaming across different types of wireless networks, quality of service guarantees, and support for a variety of services. This awareness has led to research activities directed toward intersystem and global roaming, and can be noticed in numerous products like multimode handsets, interworking gateways, and ongoing standards and research work on intersystem roaming. The authors of this article proposed a global mobility management framework to support seamless roaming across heterogeneous wireless networks. In this article we provide details on the use of the framework to support roaming across cellular and wireless local area networks. Highlights of the framework include a robust architecture for mobility management for varying user mobility spans, provisioning for QoS mapping, intersystem message translation, and mechanisms in the WLAN to support user-subscribed services. Performance aspects related to handoff delays, data redirection, and processing overheads are presented and discussed. Performance comparison of intersystem roaming between cellular and WLAN with and without the framework is presented.