Session Continuity Research Articles

Decentralized Handoffs in Heterogeneous Networks: A Kernel Module Approach

proposed solution is a Linux kernel module approach to vertical handoff for heterogeneous networks. We develop a kernel module that accomplishes the handoff process between various network interfaces supporting IP. This addresses seamless continuity, handoff decision & interface selection problems faced during the vertical handoff. This module is integrated into the Linux kernel and works for all the multimedia networking applications running on Linux systems. The handoff can be achieved at the client devices and there is no need of any centralized handoff agents or servers required. Linux being the fastest growing operating system for both wired & wireless devices and the flexibility it offers for the developer makes it the most suitable for the implementation of this solution. This paper reviews how the proposed module running at the kernel level of Linux operating system maintains seamless continuity in heterogeneity. KeywordsNetworks, vertical handoff, Linux Kernel M odule, WLAN, multimedia, seamless session continuity

Network Mobility in satellite networks: architecture and the protocol

Mobility management is required to ensure the session continuity for multiple Internet Protocol-enabled devices onboard a satellite that hands off between ground stations. Network Mobility NEMO can efficiently manage the mobility of multiple Internet Protocol-enabled devices that are connected as a mobile network. However, existing mobility management solutions for satellite networks are unable to route through intermediate satellites links when a direct connection with a ground station is lost. We proposed an architecture of NEMO in satellite networks with routing through multiple satellite links using nesting, where a mobile network connects to another mobile network. However, NEMO Basic Support Protocol can be inefficient in satellite networks because of poor nesting formation leading to the routing loop, inefficient routes, and overloaded links. We extended NEMO Basic Support Protocol for the efficient use in satellite networks by augmenting it with a decision criteria for the nesting. Results verify that the extended protocol ensures loop-free and continuous connection despite the loss of direct connection to the ground and provides an insight on how to form the nested NEMO to avoid overloading. The architecture and the extended NEMO protocol can be used for the efficient and continuous transfer of data from satellite networks to the ground. Copyright © 2011 John Wiley & Sons, Ltd.

Secure Network Mobility (SeNEMO) for Real-Time Applications

The IETF NEtwork MObility (NEMO) working group has considered how to enable an entire network to move from one location to another. Mobile Virtual Private Network (VPN) has been developed to secure mobile user's communication between untrusted external networks and the protected private internal network. However, the IETF's mobile VPN does not address how to support NEMO. In addition, it is not suitable for real-time applications. In this paper, we propose architecture and protocols to support VPN in NEMO, which is called Secure NEMO (SeNEMO). The proposed SeNEMO, based on Session Initiation Protocol (SIP), is specifically designed for real-time applications over VPN. It allows an entire network to move and still maintains session continuity. In addition to analyzing the security vulnerabilities, we also propose analytical models to evaluate the performance of the proposed SeNEMO. The analysis is validated by extensive simulations. The results show that the proposed SeNEMO can reduce signaling cost significantly.

Network virtualization as an integrated solution for emergency communication

In this paper the Virtual Private Ad Hoc Networking (VPAN) platform is introduced as an integrated networking solution for many applications that require secure transparent continuous connectivity using heterogeneous devices and network technologies. This is done by creating a virtual logical self-organizing network on top of existing network technologies reducing complexity and maintaining session continuity right from the start. One of the most interesting applications relies in the field of emergency communication with its specific needs which will be discussed in this paper and matched in detail against the architecture and features of the VPAN platform. The concept and dynamics are demonstrated and evaluated with measurements done on real hardware.

Vertical handovers among different wireless technologies in a UMTS radio access-based integrated architecture

The demands for accessing services at high data rates while on the move, anyplace and anytime, resulted in numerous research efforts to integrate heterogeneous wireless and mobile networks. The focus was mainly put on the integration of the Universal Mobile Telecommunications System (UMTS) and the wireless local area network (WLAN) IEEE 802.11, which is beneficial in terms of capacity, coverage and cost. With the advent of IEEE 802.16(e) the attention of the research community was shifted to its interworking, on one side, with complementary WLANs, and on the other, with UMTS for extra capacity. In addition, there has been also research on UMTS interworking with different broadcasting systems, including the Digital Video Broadcasting system for handheld devices (DVB-H). All these research activities resulted in various heterogeneous architectures where the interworking was performed at different levels in the network. In this article, we address the integration at the UMTS radio access level, known also as very tight coupling. This integration approach exhibits good vertical handover performance and may allow for seamless session continuity during the handover. However, it is a technology specific solution, where not all the mechanisms applied to the integration of one wireless technology can be straightforwardly reused for embedding another. This integration approach introduces various modifications to UMTS that have to be standardized, which makes it a long-term solution. We present here the general architecture for the integration at the UMTS radio access level and discuss the extension of the architectural framework for various types of access systems with as few as possible additional modifications. The focus of the work is put on the vertical handovers. We discuss various vertical handovers among WCDMA, IEEE 802.11, IEEE 802.16e and DVB-H in the considered heterogeneous architecture. We present new handover types, describe the vertical handover procedures and provide performance evaluation of the vertical handovers in different scenarios and for different combinations of the wireless access technologies.

Intelligent connection manager for seamless interworking of multi-technology mobile devices

As wireless service providers ramp up their Long Term Evolution (LTE) installations, and telecommunications and cable operators continue to expand Wi-Fi coverage, 100 percent wireless coverage with overlapping areas of 3G, 4G, and Wi-Fi access is becoming a reality. Ensuring that a multi-mode device can roam across different radio access technologies while maintaining seamless session and service continuity across virtual private network (VPN), Voice over Internet Protocol (VoIP), and streaming video applications is critical. Differences in 3GPP, 3GPP2, and WiMAX standards led to the absence of uniform interworking solutions. Specific interworking standards per access technology pair define the behavior and interfaces for common core network components including the IP anchor, AAA, and HSS, as well as the IP Multimedia Subsystem (IMS). This paper discusses the Intelligent Wireless Connection Manager (IWCM), a critical component of a mobile device platform that enables seamless and transparent inter technology mobility for user applications through IP session continuity, make-before-break handoff algorithms, and uniform quality of service (QoS) and policy management APIs.

Improving session continuity through user mobility tracking for EPS inter‐serving gateway handover

ABSTRACTThe Evolved Packet System (EPS) is standardized to support a common IP‐based core network with heterogeneous radio accesses in the latest 3GPP release. In the EPS, the Policy and Charging Control (PCC) framework provides dynamic policy control combined with real‐time charging management. Long core network signaling for PCC degrades session continuity performance during handover. In this paper, we investigate the handover for an EPS session. Based on the results, we propose a proactive scheme along with a user mobility tracking model to improve session continuity. More specifically, our proposed scheme attempts to reduce PCC reauthorization signaling delay during the handover procedure. Then, we formulate a Markov process to model the user mobility pattern and to derive the session continuity probability. Numerical results show that our scheme can significantly keep the session continuity at a user acceptable level even when the mobility pattern is high. We also provide guidelines for operators to set up the network configuration parameters according to various traffic conditions. Copyright © 2011 John Wiley & Sons, Ltd.

The MIH-based vertical handover method for Wi-Fi and WiMAX integrated network

The integrated network of WLAN and WMAN can take advantage of them to offer high quality service. Vertical seamless handover between different wireless systems is possible while the internet's quality of service (QoS) mechanisms are difficult to integrate into the handover procedures. IEEE 802.21 media independent handover (MIH) is developing standards to enable handover and interoperability between heterogeneous network types including both 802 and non 802 networks. This protocol defines method to provide the link layer intelligence and other related network information to the upper layers to optimise handovers between heterogeneous media. In this paper, we propose a scheme to make vertical handover between IEEE 802.11 WLAN network and IEEE 802.16 worldwide interoperability for microwave access (WiMAX) network based on IEEE.21 MIH. We propose the method to support vertical handover using MIH for two different scenarios. According to the simulation results, this proposal can decrease system overhead caused by handover and provides session continuity for internet users.

Fixed mobile convergence: challenges and solutions

Fixed mobile convergence is an emerging technology, which aims at integration and creation of a unified communication infrastructure from fixed and wireless mobile networks. In this converged communication infrastructure, users move across networks and access services seamlessly using different devices. Voice and video over IP is one of the emerging technologies in the realization of FMC. In this article we first discuss the features and technological requirements of FMC networks. We then present an architecture for implementing FMC and describe how to realize the voice call continuity of VoIP sessions using the current IP infrastructure. We further identify the requirements for VVoIP in ensuring video call continuity as well as the challenges associated with the migration from voice to multimedia services.

Predictive Dynamic Uplink /Downlink Resource Reservation for Vertical Handoff Optimization in 4G Networks

The fourth generation of mobile wireless networks (4G) is expected to be the most promising architecture for QoS provision due to its scalability, convenience for mobility support and capability of interworking heterogeneous radio access networks, which ensure both session continuity and QoS support. One major design issue of the 4G is the support of optimized handoff functionalities. More specifically, total disruption during a handoff should be minimized and its complexity hidden to end users. In this regard, the authors focus on developing new dynamic predictive resource reservation schemes in 4G for both uplink and downlink to maximize handoff success probability. The paper illustrates how to reserve radio resources according to future mobile terminal location expressed in a probabilistic way, to load conditions or target Base Station/Access point BS/AP and to the specificity of the data structure of each access network. Different resource reservation algorithms are devised. The objective is to efficiently utilize wireless radio resources, enhance the handoff performances and improve system performance.

10th international symposium on the synthesis and applications of isotopes and isotopically labelled compounds—synthesis of compounds labelled with long‐lived isotopes Session 17, Thursday, June 18, 2009

AbstractThis session is a continuation of Session 1. A number of methods detailing the synthesis of tritiated compounds as well as a discussion on the handling of tritium on a multi‐Curie scale are presented. In addition, the descriptions of a number of preparations of individual isotopically labelled compounds are detailed. Copyright © 2010 John Wiley & Sons, Ltd.

IMS-Compliant management of vertical handoffs for mobile multimedia session continuity

The recent advances in wireless client devices and the crucial role of multimedia communications in our society have motivated relevant standardization efforts, such as the IP multimedia subsystem, to support session control, mobility, and interoperability in all-IP next-generation networks. IMS has already driven the design of commercial mobile multimedia, but exhibits limited support for service continuity during handoffs. In particular, it omits advanced techniques to reduce/eliminate handoff delays, especially during vertical handoffs (i.e., change of the wireless technology employed by a client to access the wired Internet, e.g., from UMTS to WiFi). We propose an original solution for session continuity based on the primary design guideline of cleanly and effectively separating the signaling plane (for session reconfiguration via SIP) from the media delivery plane (data transmission and related handoff management operations). Our optimized handoff management techniques exploit terminal-based decentralized predictions to minimize service-level handoff delays. Different from other recent related work, our proposal fully complies with the standard IMS infrastructure and works at the application level. The reported experimental results point out that our solution, available as an open source tool for the IMS community, reduces playout interruption times relevantly by introducing a limited and scalable signaling overhead.

Solution to stalemate situation of mobile home Agent

Based on the tree model of access routers of nested mobile network, a solution to crack the stalemate situation of mobile home Agent was proposed. In comparison with its counterparts, the proposed scheme could decrease network handover delay and save more overhead in traffic from and to mobile network with deeper nesting while guaranteeing the session continuity between the mobile network nodes and any correspondent from the Internet and among nodes from floating nested mobile networks as well.

Handover Control Method Using Resource Reservation in Mobile Multimedia Networks

When handover events occur during the transmission of multimedia traffic, efficient handover control procedures and radio resource allocation are necessary to maintain the same QoS of transmitted multimedia traffic because the QoS may be degraded by additional delay and information loss. In this paper we propose a new handover control method for the next generation mobile multimedia networks, in which the handover setup process is done in advance of a handover request by predicting the handover cell from mobile terminal's current position. The handover procedures for real-time sessions are performed based on the handover cell information and the resource reservation condition. The radio resources in the estimated adjacent cells should be reserved and allocated to guarantee the continuity of the real-time sessions. We conduct a simulation model that is focused on the handover failure rate and packet loss rate. The simulation results show that our proposed method provides better performance than the previous methods.

An Enhanced Multihoming Support Scheme with Proxy Mobile IPv6 for Convergent Networks

This paper analyzes the limitations of the multihoming support in the Proxy Mobile IPv6 protocol, then proposes an enhanced multihoming support scheme based on a per-interface address configuration method. The proposed scheme can provide a more flexible multihoming support and also maintain application session continuity during a handoff between two interfaces by using IPv6 extension headers. Plus, flow distribution with filters is also used to realize the advantages of multihoming. Simulation results with the OPNET validate the proposed multihoming support scheme for convergent networks.

Designing VoIP session management over interworked WLAN-3G networks

In an all-IP internetworked heterogeneous environment, ongoing VoIP sessions from roaming users will be subject to frequent vertical handoffs across network boundaries. Ensuring uninterrupted service continuity for these handoff calls requires successful session management among the participating access networks. As such, a mobility-aware novel interworking network design (interconnecting UMTS and WLAN over an IP-based common platform) [1] is presented in this article that facilitates VoIP session management, including session establishment and seamless session handoff across different networks. For comparison purposes, VoIP session management is evaluated in terms of session establishment, handoff delays, transient packet loss, end-to-end traffic delays, and jitter value for different voice codecs, which demonstrate satisfactory and feasible results. In the event (e.g., network congestion, buffer overflow) that session continuity cannot be guaranteed (also known as outage) across network boundaries, this article proposes an algorithm that compensates the user by reducing the unit service charge of future sessions (governed by the outage period) through a noncooperative game-theory-based pricing mechanism.

Secure ad hoc networks [Message from the Editor-in-Chief

This issue consists of two special topic sections and two articles accepted from open call. The first special topic section focuses on Security in Ad Hoc and Sensor Networks, and includes five articles. The second special topic section focuses on Wireless Sensor Networking and includes five articles. The two articles accepted from open call submissions both are related to session continuity during handoffs in heterogeneous mobile networks.

An overview of IEEE 802.21: media-independent handover services

In recent years multitechnology-enabled terminals have become available. Such multimode terminals pose new challenges to mobility management. In order to address some of these challenges, the IEEE is currently working on a new specification on media-independent handover services (IEEE 802.21 MIH). The main aim of this specification is to improve user experience of mobile terminals by enabling handovers between heterogeneous technologies while optimizing session continuity. In this article we provide an overview of the current status of the IEEE 802.21 specification.

An Efficient Multicast-based Binding Update Scheme for Network Mobility

Mobile IP (MIP) is the solution supporting the mobility of Mobile Nodes (MNs), however, it is known to lack the support for NEtwork MObility (NEMO). NEMO manages situations when an entire network, composed of one or more subnets, dynamically changes its point of attachment to the Internet. NEMO Basic Support (NBS) protocol ensures session continuity for all the nodes in a mobile network, however, there exists a serious pinball routing problem. To overcome this weakness, there are many Route Optimization (RO) solutions such as Bi-directional Tunneling (BT) mechanism, Aggregation and Surrogate (A&S) mechanism, Recursive Approach, etc. The A&S RO mechanism is known to outperform the other RO mechanisms, except for the Binding Update (BU) cost. Although Improved Prefix Delegation (IPD) reduces the cost problem of Prefix Delegation (PD), a well-known A&S protocol, the BU cost problem still presents, especially when a large number of Mobile Routers (MRs) and MNs exist in the environment such as train, bus, ship, or aircraft. In this paper, a solution to reduce the cost of delivering the BU messages is proposed using a multicast mechanism instead of unicasting such as the traditional BU of the RO. The performance of the proposed multicast-based BU scheme is examined with an analytical model which shows that the BU cost enhancement is up to 32.9% over IPDbased, hence, it is feasible to predict that the proposed scheme could benefit in other NEMO RO protocols.

On the enhancement of mobility and multimedia communications in heterogeneous RANs

Ambient Networks (AN) aim to embrace the heterogeneity arising from different network technologies such that it appears homogeneous to the potential users at the level of network service provisioning. This paper focuses on the employment of a State Transfer Module (STM) in AN for enhancing mobility and minimising the impact of multimedia service discrepancy (e.g., security, session continuity) by supporting the transfer of authentication and authorisation states upon handoff as well as supporting multimedia session continuation while the users roam and handoff across heterogeneous wireless networks.