Kenichi Taniuchi

IEEE 802.21: Media independent handover: Features, applicability, and realization

Providing users of multi-interface devices the ability to roam between different access networks is becoming a key requirement for service providers. The availability of multiple mobile broadband access technologies, together with the increasing use of real-time multimedia applications, is creating strong demand for handover solutions that can seamlessly and securely transition user sessions across different access technologies. A key challenge to meeting this growing demand is to ensure handover performance, measured in terms of latency and loss. In addition, handover solutions must allow service providers, application providers, and other entities to implement handover policies based on a variety of operational and business requirements. Therefore, standards are required that can facilitate seamless handover between such heterogeneous access networks and that can work with multiple mobility management mechanisms. The IEEE 802.21 standard addresses this problem space by providing a media-independent framework and associated services to enable seamless handover between heterogeneous access technologies. In this article, we discuss how the IEEE 802.21 standard framework and services are addressing the challenges of seamless mobility for multi-interface devices. In addition, we describe and discuss design considerations for a proof-of-concept IEEE 802.21 implementation and share practical insights into how this standard can optimize handover performance.

Media-independent pre-authentication supporting secure interdomain handover optimization

Handovers may cause delays and packet losses that affect real-time communication performance. Mobility protocols at several layers are designed to support handover, but they need to be optimized to ensure high-quality application performance. Existing optimization techniques are not sufficient to take care of interdomain and intertechnology handovers involving different access technologies, such as Wi-Fi, GSM, CDMA, and WiMAX. We categorize several types of handover, describe handover delay components, and propose a handover optimization framework called media independent pre-authentication that can provide optimizations for interdomain and intertechnology handover in a manner that is transparent to mobility management protocols. In addition, we also present experimental results demonstrating that this framework can achieve a significant reduction in handover delays for both network-layer and application-layer mobility management protocols.

Seamless proactive handover across heterogeneous access networks

Dual-mode handsets and multimode terminals are generating demand for solutions that enable convergence and seamless handover across heterogeneous access networks. The IEEE 802.21 working group is creating a framework that defines a Media Independent Handover Function (MIHF), facilitates handover across heterogeneous access networks, and helps mobile users experience better performance during mobility events. In this paper, we describe this 802.21 framework and also summarize a Media-independent Pre-Authentication (MPA) mechanism currently under discussion within the IRTF that can further optimize handover performance. We discuss how the 802.21 framework and the MPA technique can be integrated to improve handover performance. Finally, we describe a test-bed implementation and validate experimental performance results of the combined mobility technique.

MPA assisted optimized proactive handoff scheme

In order to support session-based real-time communication in a highly mobile environment it is desirable to limit end-to-end delay, jitter and packet loss at a certain threshold level. This paper describes a framework of media-independent pre-authentication (MPA), a new handover optimization mechanism that has a potential to address issues on existing mobility management protocols and mobility optimization mechanisms to achieve these values. MPA is a mobile-assisted, secure handover optimization scheme that works over any link-layer and with any mobility management protocol. This paper also presents an initial implementation of MPA and performance results to show how existing protocols could be leveraged to realize the functionalities of MPA and provide the desired results.

An Experimental Study of Location Assisted Proactive Handover

Traditionally, signal-to-noise ratio of a mobile determines the handoff dynamics of the mobile. But in certain cases, precise location of the mobile augmented by information services, such as IEEE 802.21 MIS, can expedite the handoff with similar performance results. We illustrate an experimental system that takes advantage of the mobiles relative location with the neighboring access point to perform proactive handoff. It keeps track of the current location of the mobile and then uses the information from the neighboring networks to help perform the proactive handoff. Proactive handover technique helps the mobile to communicate with these networks before the handover is complete thereby reducing the delay and packet loss. In some cases, location-assisted handover could prove to be more useful compared to the handover technique based on signal-noise-ratio.

Secure universal mobility for wireless internet

The advent of the mobile wireless Internet has created the need for seamless and secure communication over heterogeneous access networks such as IEEE 802.11, WCDMA, cdma2000, and GPRS. An enterprise user desires to be reachable while outside ones enterprise networks and requires minimum interruption while ensuring that the signaling and data traffic is not compromised during ones movement within the enterprise and between enterprise and external networks. We describe the design, implementation and performance of a Secure Universal Mobility (SUM) architecture. It uses standard protocols, such as SIP and Mobile IP, to support mobility and uses standard virtual private network (VPN) technologies (e.g., IPsec) to support security (authentication and encryption). It uses pre-processing and make-before-break handoff techniques to achieve seamless mobility (i.e., with little interruption to users and user applications) across heterogeneous radio systems. It separates the handlings of initial mobility management and user application signaling messages from user application traffic so that VPNs can be established only when needed, thus reducing the interruptions to users.

Dynamic Buffering Control Scheme for Mobile Handoff

In a mobile environment, as a mobile node moves from one point of attachment to another during an ongoing application session it is subjected to packet loss due to network and link layer transition. Such packet loss affects the quality of ongoing communication session such as interactive VoIP traffic and streaming media. We provide a solution to this scenario by buffering packets for the mobile node at an access router or network node near the edge of the network where mobile may be moving away from or moving towards. The buffered packets are then forwarded to the mobile node once the handoff process completes. The buffering scheme is used in conjunction with existing mobility protocols, access protocols or as an independent network or link layer mechanism. Ability to control the buffer dynamically provides a reasonable trade-off between delay and packet loss which is within the threshold limit for real-time communication. The overview and mechanisms of such schemes are described and comparisons on existing buffering schemes are also provided

Experimental analysis of multi interface mobility management with SIP and MIP

We provide an experimental analysis of MIMM (multi-interface mobility management) demonstrated in a heterogeneous network involving 802.11b and CDMA access technologies. We have experimented WAN-LAN handoff for real-time service (voice and video) in the testbed. The subnet handoff managed by MIMM was done seamlessly in this environment and is proved to support real-time application effectively. Both application layer and network layer mobility management were used in the experiment and their results were analyzed for real-time traffic.

Realization of IEEE 802.21 services and preauthentication framework

Providing users of multi-interface devices the ability to roam between different access networks is becoming a key requirement for service providers. The availability of multiple mobile broadband access technologies together with increasing use of real time multimedia applications is creating strong demand for handover solutions that can seamlessly and securely transfer user sessions across different access technologies. In this paper, we discuss how the IEEE 802.21 standard and its services address the challenges of seamless mobility for multi-interface devices. We focus on a proof-of-concept implementation that integrates IEEE 802.21 services and a pre-authentication framework, realizing different possible usage scenarios to optimize handover performance. We describe the implementation of two handover scenarios using the 802.21 Services: the first one is initiated by the mobile node and the second one is initiated by the operator network. We compare the two scenarios and discuss their respective benefits. Finally, we describe the implementation challenges and lessons learned through this exercise.

Secure universal mobility for wireless Internet

The advent of the mobile wireless Internet has created the need for seamless and secure communication over heterogeneous access networks such as IEEE 802,11, WCDMA, cdma2000, and GPRS. An enterprise user desires to be reachable while outside ones enterprise networks and requires minimum interruption while ensuring that the signaling and data traffic is not compromised during ones movement within the enterprise and between enterprise and external networks. We describe the design, implementation and performance of a Secure Universal Mobility (SUM) architecture. It uses standard protocols, such as SIP and Mobile IP, to support mobility and uses standard virtual private network (VPN) technologies (e.g., IPsec) to support security (authentication and encryption.) It uses pre-processing and make-before-break handoff techniques to achieve seamless mobility across heterogeneous radio systems. It separates the handlings of initial mobility management and user application signaling messages from user application traffic so that VPNs can be established only when needed, thus reducing the interruptions to users.