Lawrence Cheng

ContextWare support for network and service composition and self-adaptation

A crucial prerequisite for building context-aware networks is an integrated infrastructure for sensing, processing, managing and disseminating network context information to network entities and user-facing applications. This requirement is especially important in ambient networks, a class of networks that exploit the inherent heterogeneity seen in todays wireless networks in order to share diverse resources and services across different but cooperating networks. We discuss ContextWare, our architectural solution for making ambient networks context-aware, and present a programmable approach to its realization. We relate some of our experiences in building and validating a prototype and demonstrating its support for network and service composition, as well as self-adaptation, using a reference scenario.

Self-Management of Context-Aware Overlay Ambient Networks

Ambient networks (ANs) are dynamically changing and heterogeneous as they consist of potentially large numbers of independent, heterogeneous mobile nodes, with spontaneous topologies that can logically interact with each other to share a common control space, known as the ambient control space. ANs are also flexible i.e. they can compose and decompose dynamically and automatically, for supporting the deployment of cross-domain (new) services. Thus, the AN architecture must be sophisticatedly designed to support such high level of dynamicity, heterogeneity and flexibility. We advocate the use of service specific overlay networks in ANs, that are created on-demand according to specific service requirements, to deliver, and to automatically adapt services to the dynamically changing user and network context. This paper presents a self-management approach to create, configure, adapt, contextualise, and finally teardown service specific overlay networks.

Self-organising Management Overlays for Future Internet Services

Networks are becoming service-aware implying that all relevant business goals pertaining to a service are fulfilled, and also the network resources are used optimally. Future Internet Networks (FIN) have time varying topology (e.g. such networks are envisaged in Autonomic Internet [1], FIND program [2], GENI program [3], FIRE program [4], Ambient Networks [5], Ad-hoc networks [6]) and service availability and service context change as nodes join and leave the networks. In this paper we propose and evaluate a new self-organising service management system that manages such changes known as the Overlay Management Backbones (OMBs). The OMB is a self-organising solution to the problem space in which each OMB node is dynamically assigned a different service context task. The selection of OMB nodes is conducted automatically, without the need of relatively heavy-weighted dynamic negotiations. Our solution relies on the scalability and dynamicity advantages of Distributed Hash Tables (DHTs). This system is needed to select continuously, automatically, and dynamically a set of network nodes, to become responsible for collecting the availability information of service context in the changing network. This solution advances the state of the art avoiding dynamic negotiations between all network nodes reducing management complexity and cost for bandwidth-limited environments.

Towards distributed hash tables (De)composition in ambient networks

When different wireless networks come in close proximity there is often a need for them to logically combine, or compose. We focus on a known research problem particularly in Ambient Networks (ANs), where hetero-geneous Distributed Hash Tables (DHTs) contained in these wireless networks need to merge or divide as a result of these dynamic (de)composition processes, respectively. We present two novel DHT (de)composition models for ANs, known as absorption and gatewaying, that are designed to handle (de)composition of DHTs in different AN network environments, with minimal disturbance to existing member nodes.

Ambient Networks Management Challenges and Approaches

System management addresses the provision of functions required for controlling, planning, allocating, monitoring, and deploying the resources of a network and of its services in order to optimize its efficiency and productivity and to safeguard its operation. It is also an enabler for the creation and sustenance of new business models and value chains, reflecting the different roles the service providers and users of a network can assume. Ambient Network represents a new networking approach and it aims to enable the cooperation of heterogeneous networks, on demand and transparently, to the potential users, without the need for pre-configuration or offline negotiation between network operators. To achieve these goals, ambient network management systems have to become dynamic, adaptive, autonomic and responsive to the network and its ambience. This paper discusses relationships between the concepts of autonomous and self-manageability and those of ambient networking, and the challenges and benefits that arise from their employment.

Service-aware Overlay Adaptation in Ambient Networks

Developing service-aware self-adaptation systems in heterogeneous and rapidly changing wireless networks such as ambient networks is a challenging issue. Key research areas are adaptation policy definition, network context monitoring, and adaptation policy enforcement. In this paper, we present the ambient virtual pipe platform (AVPP) - that provides a flexible approach towards the creation and management of self-adaptation service-aware overlays in ambient networks

Towards ambient networks management

Ambient Networks (AN) are under development and they are based on novel networking concepts and systems that will enable a wide range of user and business communication scenarios beyond todays fixed, 3rd generation mobile and IP standards. Central to this project is the concept of Ambient Control Space (ACS) and the Domain Manager control function, which manages the underlying data transfer capabilities and presents a set of interfaces towards the supported services and applications. Network Management Systems of Ambient Networks must work in an environment where heterogeneous networks compose and cooperate, on demand and transparently, without the need for manual (pre or re)-configuration or offline negotiations between network operators. To achieve these goals, ambient network management systems must become dynamic, distributed, self-managing and responsive to the network and its ambience. This paper describes the different management research challenges and four complementary solution approaches (i.e. Pattern-based Management, Peer-to-Peer Management, (Un)PnP Management, Traffic Engineering Management Application Approaches) that enable efficient management of ambient networks, and the relationships between them, and presents the main results achieved so far.

A low-cost accurate speed-tracking system for supporting sprint coaching:

Accurate speed and split-time information on sprinters is crucial in coaching support. Furthermore, speed and stride parameters (i.e. contact time, stride frequency, and stride length) are important in research on the biomechanics of running. Existing speed-tracking systems for sprinting are expensive, unable to support multiple competing athletes, involve a complicated set-up procedure, or are not sufficiently accurate. This paper describes the design, evaluation results, and application scenarios of a novel, practical, and cost-effective light-sensor network system (commissioned at the National Indoor Athletics Centre, Cardiff, UK) that is capable of capturing criterion-comparable split-time information on simultaneously competing sprinters for long- and short-term coaching support and for biomechanics and sports science research purposes. This unique system is specifically designed to support coaching activities on a daily basis. It was also shown that the light-sensor network system can be integrated with other body-attached measurement systems to achieve continuous tracking of position, speed, and stride parameters of a race.

Stochastic maintenance of overlays in structured P2P systems

Peer-to-peer networks have widespread and got commonly used in our every day life. The maintenance strategy of overlays is a key factor in structured peer-to-peer networks. Most of these routing overlays scale well even for a very large number of nodes in static and quasi-static networks. However, providing good performance in dynamic network environments is still an open question. We analyse maintenance of routing overlays in structured P2P systems under churn. We exploit the inherent difference in the role of local (short-range) and long-range connections. We propose a dual strategy for the routing overlays: (i) we reuse strict, proactive and self-stabilizing short-range connection maintenance and (ii) we define a novel, loose and stochastic long-range connection maintenance mechanism, which can significantly reduce maintenance overhead in large networks with high churn rates without affecting routing performance. We use Kleinbergs small worlds model to describe and (re)construct long-range connections. We formally describe the evolution of our proposed system under churn by a Markov chain model and we derive its steady state maintenance traffic (overhead). We formally show that our maintenance method scales logarithmically with the systems size, which is the theoretical lower bound for maintenance traffic to ensure connectivity of the network. Finally, we numerically analyse overlay and maintenance behaviour using various protocol parameter settings and conclude that an overlay with our maintenance method is stable at very high levels of churn.

Self-Management in Ambient Networks for Service Composition

This paper describes the concepts and challenges of self-managing management-layer network composition and service composition in Ambient Networks. A set of requirements are identified. This paper describes the concept of Ambient Virtual Pipe (AVP), which is an autonomic, secure, QoS-assured, self-adapted context aware management service overlay network that provides a secure and QoS-assured environment for AN service composition. The AVP is supported through a programmable platform, and is capable of dynamic deployment of new management services.