Session Handoff Research Articles

An IMS-Based Advanced Handoff Scheme for Wi-Fi/LTE Integrated Framework

Integrating heterogeneous access technologies to provide users with always best connected services is one of the primary objectives of fourth-generation wireless technologies. The major research issue in an integrated framework is to enable mobile users with fast and smooth connectivity while switching between heterogeneous access technologies. In this paper, an integration framework for Wireless Fidelity/Long-Term Evolution access technologies is presented with IP Multimedia Subsystem for service provisioning. An inter-domain handoff scheme called SIP advanced handoff is proposed which utilizes improved Session Initiation Protocol (SIP) and Mobile IPv6 with a multilayer approach which enables fast and smooth connectivity with minimized handoff latency and improved throughput. A simulation is carried out using NS2, and the performance characteristics are studied. The measured handoff performance metrics reveal that successful video session handoffs are achieved with acceptable quality of services levels and further that the proposed scheme shows better performance than the conventional scheme.

Integrated Multi-service Handoff Mechanism with QoS-Support Strategy in Mobile Cloud Computing

Mobile devices are becoming the primary platforms for many users who always roam around and access the cloud computing applications. Using cloud computing services extensively and offloading local applications to the cloud, facilitate mobile devices keep multiple services online at the same time. Since the mobile device may move fast and session handoff among access networks comes up frequently, multiple services initiate handoff procedure results in lots of redundant signaling. The current handoff mechanisms only make the handoff control for each service individually, which brings much unnecessary energy consumption and ignores the different Quality of Service (QoS) requirement during handoff execution. To solve these issues, we propose an improved multi-services handoff mechanism, which uses the list method of session initial protocol to make all active services execute handoff together. And considering to support the QoS for each active service during handoff procedure, the differentiate policy for multi-service media transfer is included based on the integrated handoff signaling. Analytic model and simulation are developed to investigate the new mechanism. The results demonstrate that the improved multi-service handoff mechanism can efficiently save energy consumption for mobile devices and realize seamless handoff.

Emerging research areas in SIP-based converged services for extended Web clients

The convergence of Next Generation Networks and Internet-based rich applications are generating relevant industrial opportunities in the market of mobility-enabled services. Even if this trend is widely recognized, there are still a few industrial-level solutions that effectively support session mobility in a transparent way and with the capability of openly integrating with existing and legacy applications. In this paper we propose a SIP-based hybrid architecture for Web session mobility that offers content sharing and session handoff between Web browsers. In addition, its technical originality includes integrating a SIP stack into a Web browser, thus offering the advantage of extending a Web browser to act as a SIP client. Lastly, a rich set of control services that prevent abuse of content sharing and session handoff are introduced into the proposed system. The implemented solution uses SIP in a standard way to migrate Web sessions between Web browsers; it is made up of a SIP integrated Web client and a converged (SIP and HTTP) Application Server that can be easily used to enable session mobility in any kind of Web-based application. In addition, the implemented system has recently evolved to a framework for developing different kinds of converged services over the Internet, analogously to what is possible with Google Wave and the existing telephony APIs. Finally, the paper reports the evaluation of the proposed framework and of the employed technologies, together with directions of future work, in terms of both extension to other application domains and exploration of research areas/models that can benefit form the adoption of SIP and Web-related solutions.

The multimedia service session handoff method in heterogeneous wireless networks

The IP Multimedia Subsystem (IMS) can provide multimedia services between heterogeneous wireless networks. But the efficiency of the service session handoff will bring a significant impact to user experience. For the integration of heterogeneous wireless networks, we propose a Session Initiation Protocol (SIP) based multimedia service session handoff method named MS²HM. To reduce the handoff delay between heterogeneous wireless networks, the MS²HM uses the methods of advance registration and old-new address temporary matching. We modelled the node processing delay and network transmission delay, and analyse the total delay and the packet loss rate of the MS²HM. Specially, this paper contrastively analyses the handoff delay under different frame error control in the 3G-WLAN integrated network, and the result shows that MS²HM has lower handoff delay than the method proposed by Wedlund and Schulzrinne. The MS²HM can meet the low delay and low packet loss rate requirements of IMS service session handoff between heterogeneous wireless networks, and ensure the QoS of the IMS services.

Analysis of Session Handoff Probability in NEMO-Based Vehicular Networks

Network Mobility (NEMO) basic support protocol enables seamless mobility in vehicular networks. In this paper, we analyze the session handoff probability in NEMO-based vehicular environments. We develop analytical models for the session handoff probability. In particular, we derive the session handoff probabilities for riding and taking off users. Numerical results are given to illustrate the effects of the cell residence time, the numbers of road segments/intersections, the velocity, and the signal delay.

A SIP-based web client for HTTP session mobility and multimedia services

This work leverages Session Initiation Protocol (SIP) transportation and mobility mechanism to transfer session data between two Web browsers. In addition, a Web browser can now act as an adaptive User Agent Client to surf the Internet and make voice calls as a SIP client. It is a novel work that uses SIP to transfer session data between Web browsers and borrows SIP Mobility types to introduce new service namely, content sharing and session hand-off, to the Web browsing experience. Referred to as a SIP-based HTTP session mobility service, it offers personal mobility to end users, and facilitates session mobility in Web browsing. While content sharing refers to the ability to view the same Web resource on two Web browsers and does not require moving session data, session hand-off refers to the migration of a Web session with its session data (cookies, hidden form elements and rewritten URL) to another Web browser. Results showed that the integration of SIP into a Web browser does not degrade the performance of a Web browser. Results also showed that the service could not work on all websites because of the Same Origin Policy (SOP) used by Web browsers to transfer cookies. The hybrid-based architectural scheme proposed and implemented here is compared with other existing Web session migration schemes. On the service commercialization, if the privacy and security of session data could be guaranteed by the implementers, a flat rate could be periodically charged regardless of the varying session data sizes. In another sense, it could be rendered as a Value Added Service (VAS) to customers.

Seamless Video Session Handoff between WLANs

Handoff in a distributed IEEE 802.11 Wireless LAN network is a source of significant amount of problems on the video transmission environment. The visual quality of video streaming applications is lowered when stations are in handoff status. In this paper, we introduce an architecture of a session proxy (SP), which tries to preserve the quality of the streaming video upon each handoff between access points. We have evaluated thresholds of RSSI and Loss Frame Rate (LFR) for deciding the moment when the handoff process shall begin. Our solution performance was evaluated in a testbed implementation for MPEG-4 video on demand with one video server (VLS) and two FreeBSD-based access points supporting Mobile IP, DHCP Server and IAPP approach.

Mobility Management for Video Streaming on Heterogeneous Networks

This article discusses how ubiquitous video streaming platform can let people enjoy continuous multimedia services at any time, in any location, and with any computing device. There are several technical challenges to be met in the process of achieving this goal. These challenges entail developing sophisticated session handoff control, session descriptions, communication signaling, and adaptive video streaming, among other factors.

Layer 5 Session Handoff: Mobility Management for Video Streaming Sessions among Heterogeneous Networks and Devices

In the past decade, mature video processing and Internet technologies have made video services over IP feasible and increasingly popular, e.g., video-on-demand (VoD) and IPTV. Considering mobile life over heterogeneous networks, a user can exploit any device to enjoy/share pictures, videos and music at anytime and anywhere, and he may change his currently used device or attached network to another one. To manage video streaming sessions among heterogeneous networks and devices, we developed a Ubiquitous Multimedia Service Platform for Mobile Life over the Digital Home Environment (UMS-MLDH) in a 3-year (2006-2009) National Telecommunication Project (NTP). Many distinct-domainsˇ core techniques are devised and well integrated in UMS-MLDH, including session mobility management, session signaling and communication and adaptive layered video streaming over a 3-tier server-proxy-client network architecture. In our experiments, the system integration, implementation and merits of UMS-MLDH are exhibited over a hybrid Home-Vehicular-Office network.

An analytical evaluation of mobility management in integrated WLAN-UMTS networks

Ensuring uninterrupted service continuity for handoff calls in an all-IP inter-networked heterogeneous environment requires successful session management among participating access networks. As such, a mobility-aware novel interworking architecture is presented in this article that facilitates session management including session establishment and seamless session handoff across different networks. This framework conveniently enables any 3G cellular technology such as the Universal Mobile Telecommunications System (UMTS) to interwork with a given Broadband Wireless Access (BWA) technology such as the Worldwide Interoperability for Microwave Access (WiMAX) network or the Wireless Local Area Network (WLAN) under a common signaling platform. This framework exploits the IP Multimedia Subsystem (IMS) as a universal coupling mediator for real-time session negotiation and management. Next, a Queuing Theory based analytical model for evaluating the performance of vertical handoff management between these interworked 3rd Generation (3G) cellular networks and the WLANs is presented. The analysis includes vertical handoff performance measures such as delay, transient packet loss, jitter, and signaling overhead/cost. The latter part of this paper presents some results from OPNET based simulations for the verification of the analytical model and results.

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.

The handoff control scheme for computing powerless devices and its applications in the digital home network

The evolution of wireless transmission technology enables users to have multimedia services anywhere in the digital home network. In this paper, we propose a handoff control scheme called Computing Powerless Handoff (CP-Handoff) for devices without computation capability, such as the light-weight Bluetooth (LW-BT) headset. The main concern of the CP-Handoff is that the client device doesn’t have the computation capability. The main function of the computing powerless client device is to send/receive signals and play the audio data. Thus, how to have the handoff control when a computing powerless client device is switched from one access point to another access point becomes a problem to be resolved. A typical example is in the BT wireless network environment. The LW-BT headset is dedicated for audio applications and doesn’t have extra computation capability. The CP-Handoff puts all handoff computation overhead on the master BT device, such that the LW-BT headset is unaware of the handoff. Based on the proposed CP-Handoff control scheme, a Ubiquitous Audio Access Platform (UAAP) is proposed and developed to allow users to access audio files using the LW-BT headset in the digital home network when they are roaming. The evaluation results show that the proposed CP-Handoff only needs 1.17 s to prepare the AVDTP session handoff and 0.38 s for the AVDTP session handoff. The transmission of audio packets to the LW-BT headset is only suspended for 0.38 s. The audio packet buffering scheme and retransmission mechanism ensure that the LW-BT headset can resume lost audio packets during handoff.

Stateful session handoff for mobile WWW

This paper proposes a web session handoff system that can hand over not only stateless but also stateful sessions between homogenous and heterogeneous user devices to enable uninterrupted and seamless web access. The proposed system adopts a proxy-based approach and an optional client-assisted scheme in order to track and hand over session information. In the proposed system, a session is registered at a User Agent Proxy (UAP) and then tracked by the UAP so that the session can be handed over from one device via the UAP to another device. In addition to session information tracked by a UAP, the UAP can hand over more comprehensive session information by using the client-assisted scheme. Compared with client-based approaches, our design has several advantages, such as less modification to user devices, practicability, and fault tolerance. We have implemented a UAP on a PC and client programs for both PC and PDA. The implementation can successfully hand over between PC and PDA a stateful session for online shopping applications.

유비쿼터스 멀티미디어 응용을 위한 CMQ 미들웨에 프레임웍의 구현

Traditional applications are executed using the restricted resources of a single computer, do not consider contextual information, and can not support mobile users. However, ubiquitous applications provide optimal services for mobile users using the various resources of computers and the contextual information around users and devices. Thus, ubiquitous applications need to have the functionality of context awareness, user mobility and QoS adaptability. This paper design the CMQ(Context-aware, Mobility-aware, QoS-aware) middleware framework for ubiquitous applications and implement the middleware framework using Jini and Java. The implemented middleware system can process various contexts, provide the session handoff for a mobile user, and allow applications to adjust its QoS dynamically.

A scalable, distributed middleware service architecture to support mobile internet applications

Middleware layers placed between user clients and application servers have been used to perform a variety of functions to support the vision of nomadic computing across varying platforms. In previous work we have used middleware to perform a new capability, application session handoff, using a single Middleware Server to provide all functionality. However, to improve the scalability of our architecture, we have designed an efficient distributed Middleware Service layer that properly maintains application session handoff semantics while being able to service a large number of clients. We show that this service layer improves the scalability of general client-to-application server interaction as well as the specific case of application session handoff. We detail protocols involved in performing handoff and analyse an implementation of the architecture that supports the use of a real medical teaching tool. From experimental results it can be seen that our Middleware Service effectively provides scalability as a response to increased workload.