Zoltan Richard Turanyi

Design, implementation, and evaluation of cellular IP

Wireless access to Internet services will become typical, rather than the exception as it is today. Such a vision presents great demands on mobile networks. Mobile IP represents a simple and scalable global mobility solution but lacks the support for fast handoff control and paging found in cellular telephony networks. In contrast, second- and third-generation cellular systems offer seamless mobility support but are built on complex and costly connection-oriented networking infrastructure that lacks the inherent flexibility, robustness, and scalability found in IP networks. In this article we present cellular IP, a micro-mobility protocol that provides seamless mobility support in limited geographical areas. Cellular IP, which incorporates a number of important cellular system design principles such as paging in support of passive connectivity, is built on a foundation of IP forwarding, minimal signaling, and soft-state location management. We discuss the design, implementation, and evaluation of a cellular IP testbed developed at Columbia University over the past several years. Built on a simple, low-cost, plug-and-play systems paradigm, cellular IP software enables the construction of arbitrary-sized access networks scaling from picocellular to metropolitan area networks.

Comparison of IP micromobility protocols

We present a performance comparison of a number of key micromobility protocols that have been discussed in the IETF Mobile IP Working Group over the past several years. IP micromobility protocols complement Mobile IP by offering fast and seamless handoff control in limited geographical areas, and IP paging in support of scalability and power conservation. We show that despite the apparent differences between IP micromobility protocols, the operational principles that govern them are largely similar. We use this observation to establish a generic micromobility model to better understand design and performance trade offs. A number of key design choices are identified within the context of the generic model related to handoff quality and route control messaging. We present simulation results for Cellular IP, Hawaii, and Hierarchical Mobile IP, and evaluate the handoff performance of these protocols. Simulation results presented in this article are based on the Columbia IP Micromobility Software (CIMS), which is freely available from the Web (comet.columbia. edu/micromobility) for experimentation.

Performance aspects of Bluetooth scatternet formation

The emergence of Bluetooth as a default radio interface allows handheld electronic devices to be rapidly interconnected into ad hoc networks. Bluetooth allows large numbers of piconets to form a scatternet using designated nodes that participate in multiple piconets. We study the performance implications of forming scatternets from piconets. The contribution of our work is twofold. First, we establish a network model and define performance metrics for Bluetooth scatternets. Our model is derived from constraints specific to the Bluetooth technology, but is sufficiently abstract to relate to the more general field of ad hoc networking. Second, using a number of simulation studies, we relate scatternet parameters to performance metrics and discover correlations between scatternet formation rules and performance. These results reveal some important performance implications of scatternet design decisions and can serve as guidelines for future scatternet formation algorithms.

4+4: an architecture for evolving the Internet address space back toward transparency

We propose 4+4, a simple address extension architecture for Internet that provides an evolutionary approach to extending the existing IPv4 address space in comparison to more complex and disruptive approaches best exemplified by IPv6 deployment. The 4+4 architecture leverages the existence of Network Address Translators (NATs) and private address realms, and importantly, enables the return to end-to-end address transparency as the incremental deployment of 4+4 progresses. During the transition to 4+4, only NATs and end-hosts need to be updated and not the network routers. The 4+4 architecture retains the existing semantics of Internet names and addresses, and only proposes simple changes to the network layer that focus entirely on address extension. Encapsulation is used as the main tool to maintain backward compatibility. We present the design, implementation, and evaluation of the 4+4 architecture and discuss our implementation experiences and results from local and wide-area Internet experimentation. The 4+4 source code is freely available from the Web (comet.columbia.edu/ipv44) for experimentation.

A cellular IP testbed demonstrator

Cellular IP is a wireless Internet access technology that operates on mobile hosts, base stations and Internet gateways. Cellular IP combines the capability of cellular networks to provide high performance handoff and efficient location management of active and idle mobile users with the inherent flexibility, robustness and scalability found in IP networks. We provide an overview of the cellular IP routing, handoff and paging algorithms and their implementation in a pico-cellular testbed. The protocol has been under development at Columbia University for the past several years initially as a joint project between the Center for Telecommunications Research and Ericsson Research.

Experimental evaluations of feasibility and bottlenecks of IP/sup 2/ mobility management

Experimental system of IP/sup 2/ mobility management was designed and implemented in order to confirm feasibility of the protocol and identify its bottlenecks. The experimental system is based on a prototype implementation of IP/sup 2/ mobility management which runs on PC servers. Series of experiments were conducted in order to check validity of protocol sequence and impact of load status on system performance. From the feasibility tests results, it was confirmed that there was no fundamental error in IP/sup 2/ mobility management and it could interwork with other IP protocols. Throughout the bottleneck tests, degradation in performance due to limitation of the transport: mechanism was observed when the MN had relatively large number of active peers. Experimental results indicated that alternate mechanism to improve reliability of signalling messages was highly needed. From user-plane viewpoint, additional processing that is specific to IP/sup 2/ mobility management put negligible effect on the packet forwarding delay of the AR.

Distributed Service Development in Personal Area Networks

This paper presents the detailed description of the Middleware for Application Interconnection in Personal Area Networks (MAIPAN), which is designed to ease distributed service development for mobile and nomadic environment. This middleware provides a uniform computing environment for distributed applications that operate in dynamically changing personal area networks (PANs). MAIPAN hides the physical scatteredness and device configuration of the PAN and presents its capabilities as a single computer towards the applications. The solution provides easy set-up of PAN-wide applications utilizing multiple devices and allows transparent redirection of ongoing data flows when the configuration of the PAN changes. The proposed middleware interconnects services offered by applications running on different devices by creating virtual channels between the input and output outlets of the applications. Channels can be reconfigured when configuration or user needs change. In contrast to the approaches found in the literature, MAIPAN is a solution where session transfer, dynamic session management are tightly integrated with strong and intuitive access control security. A prototype implementation demonstrates the capabilities of the middleware.