Research Areas

My major research areas of interest are as follows:
Architectures and Technologies for the Future Internet
After leaving BT Research in 2009, I continued with my focus on Internet architecture related issues. The activities are a mix of technical but also community-related work.

Large-scale Publish Subscribe
Inspired by my work on wireless sensing and by discussions with Pekka Nikander and others, a growing activity in my research focusses on the viability of publish-subscribe as a possible replacement for the IP send-recv model in the current Internet. Driven by the largely publish-subscribe nature of many existing and contemporary applications but also by considerations in the privacy and security space, my research focusses on issues to be addressed when considering such radical change in the overall Internet and its underlying paradigms. The issues revolve around questions on identity (both description as well as management), privacy and security (trust being central here), naming and addressing on internetworking layer, the nature of layers in a largely publish-subscribe world in the first place, scalability of solutions, and the impact on existing applications and services, to name only a few areas. My work in this area is largely conducted within the PSIRP project as well as in the Communications Futures Program at MIT, in particular within the Privacy & Security working group.

The EIFFEL Initiative
Less a research but more of a community effort, the EIFFEL initiative aims at establishing efforts for debate and interaction among the research community, initially in Europe and eventually beyond, in the space of the Future Internet. The initiative was created by the European Commission throughout July 2006 with the EIFFEL whitepaper being the outcome of the initial work, publically presented at the Future Internet workshop in Brussels in December 2006. Several follow-ups were created since then, one of which is the proposal for a Strategic Support Action within the EU's FP7 research framework with the aim to establish such stage for debate through a concrete set of meetings and workshops to be organized. Another activity within the ICST Society aims at complementing these activities with a stage that targets business strategists and policy makers. These activities, while currently largely focussed on Europe, are expected to grow internationally through appropriately connecting to similar activities, e.g., in the US.

Mobile-Centric Wireless Sensing
Started during my time at Nokia Research, wireless sensing is an important field of activity in my research, also connecting to the problem of large-scale publish-subscribe (see below). The NORS platform, being developed and eventually open-sourced during my time at Nokia Research, lays ground for a new form of participatory sensing that could potentially involve almost every end user directly through his/her mobile device being carried around. With that, end users directly become part of the provisioning system while still consuming the outcomes of the exercise as new forms of services, such as environmental warnings, traffic re-directs based on end user reports etc. The NORS work intended to combine best practises in sensor networking (using a simple yet efficient publish subscribe system) with modern smart phone technology, enabling the easy and fast integration of future sensors but also the fast developments of applications and services in the system. While the current implementation foresees a centralized application server on a Windows machine, future deployments can easily include servers directly on mobile phones of end users (the current practise of blocking phone-to-phone IP connections in mobile networks makes such deployment hardly likely and we therefore did not undergo the effort to port the server on a mobile platform).
Future work in this space will not only focus on improvements to the platform, in particular in connection with the more general problem of large-scale publish subscribe (see below), but will also seek collaborations with academia to use the solution for their experiments on local sensing, federating the vast number of existing sensor deployments to a new form of experiments. The current open source availability of NORS makes such collaboration rather easy.

Core-Edge Dynamics
During my work on seamless mobility and applications in the Internet (see below), I encountered more and more the phenomenon of core-edge dynamics, which describes the movement of functionality between what we classically perceive as the "core" and the "edge" of the network. This movement, being caused by technological, economical, and regulatory forces, is recognized to have impacts on the current and future value chain of the telecommunication industry. In my work with MIT's Communications Futures Program (CFP), I used to co-chair the "Core-Edge Dynamics" working group (now called the Value Chain Dynamics working group), together with Prof. Charlie Fine from MIT Sloan. The working group is chartered with addressing the phenomenon of core-edge dynamics through methods of case studies, taxonomy definition, system model development, and derivation of possible future value chains. During regular small working group meetings and bi-annual large consortium meetings, industry partners such as France Telecom, Intel, British Telecom, and Nokia are working together with the faculty from MIT in this space. In addition to my work within this MIT consortium, I'm also engaged in the Mobile VCE consortium's Flexible Network programme which investigates socio-economic design approaches, based on work like that of CFP.

Seamless and Context-aware Services
After joining Nokia Research in 2000, I started my work in the area of seamless and context-aware services. This topic comprises aspects to provide protocol and service functionality in a multi-dimensional heterogeneity, i.e., in the presence of heterogeneous access networks across operators and device boundaries. It further considers the adaptation of service and application functionality based on the current context of the user. Context includes, but is not limited to, information about location, presence, current activity, affective state, or other information of the user.

Context Awareness
Context awareness aims at adapting the service and application behavior to the user's current context, such as adapting content delivery to the current location, routing calls based on the availability (expressed in the current presence information), or even news delivery based on the user's current affective state (e.g., not receiving bad news when in a bad mood). In this, I've been working on methods and techniques to discover such information throughout the network and provision the information appropriately. The focus here has been on distributed context provisioning, since I strongly believe that centralized methods do not suffice, in particular for scenarios that consider widely dispersed context information.
The considered techniques involve SIP (events) and Web Services for provisioning of context information. Further, I've been working on architectural, technological, and business impacts of context awareness. The work on context awareness has been an orchestrated effort in order to enable a view on the problem space from a networking and application point of view.

Seamless Mobility and Applications in the Internet
As one aspect in the seamless provison of IP services in the presence of heterogeneous access networks, the discovery of physically nearby access routers is a crucial problem in order to determine the target of a mobile device's IP-level handover from the currently serving access router. The existence of heterogeneous networks makes the presence of different administrative domains very likely. As a consequence, the known information regarding the logical IP distance does not suffice since logically nearby access routers might be physically far from each other. In this problem space, I've been working in the area of Candidate Access Router (CAR) discovery. Within the SEAMOBY working group of the Internet Engineering Task Force (IETF), a solution for this problem was developed throughout the course of the years 2001 to 2004. In this, I was involved in the problem statement as well as the requirements for the protocol solutions in this space. Moreover, a solution draft for this problem was submitted in March 2003, which was eventually merged into the final WG solution.
In another area of seamless mobility, I've been working on solutions to relocate service functionality throughout the mobile device's movement. In this, the Application Context Transfer Framework was developed as a solution framework that allows such relocation of higher level service functionality (presented at ICC 2003).

Collaborative Computing

Scalable Conferencing Control Service (SCCS)
Due to my work in the area of group communication protocols (especially the T.120 and Internet stuff), I began my research for the design of a scalable conferencing control service (SCCS) for tightly-coupled environments, which uses an efficient resource management scheme and multicast for a better scalability in large scenarios. SCCS provides a service functionality similar to the ITU protocol suite (T.122, T.124). In contrast to existing protocols, SCCS supports complete reconfiguration of the conference tree topology to provide an optimization of the topology for reduction of response times, e.g. for the floor control. Currently, a complete service and protocol specification is available.

ITU-based Collaborative Conferencing
My T.120 research focus was on evaluation of the existing ITU-based conference control protocols for group communication in tightly-coupled environments, i.e., the standard family T.120 that is being used in H.32x conference systems. This standard provides generic functionalities for data conferencing applications. Several weaknesses of the standard were pointed out during this work, especially in the area of scalability in large scenarios. Additionally, a combination of T.120 and the distributed platform CORBA was studied and implemented to extend the T.120 by some useful features from a user's point of view.

The Remote Paradigm
A small comic... (not really research).

Modeling and Simulation

GCDL: Group Communication Description Language
Modeling group communication scenarios is a research topic currently under discussion due to its complexitiy in terms of interaction between the entities. The main problem is that commonly used models do not take into account the high correlation of the actions in group communication scenarios and the underlying communication using conference control protocols. Thus, the observed results are not valuable due to the unrealistic assumptions of the model. To overcome these drawbacks, the GCDL framework is proposed enabling to model social protocols in group communication scenarios appropriately. With this framework, simulative as well as analytical evaluation of conferencing systems is feasible without implementing and installing the system under consideration in large environments.
The framework is extensively described in my Ph.D thesis Scalable Group Communication in Tightly-Coupled Environments.

Automata-based performance evaluation
An appropriate tool for the evaluation of the underlying protocol mechanisms is the simulation. For the evaluation of large scalable conferencing control protocols, a load model was developed based on distributed automata using the GCDL framework as described above. For that, the Specification and Description Language (SDL) is used for the description of the interactions, which is then mapped onto a simulation using an own framework for realization. This results in an interaction-based load model which can be used for performance evaluation. In my Ph.D thesis, entitled Scalable Group Communication in Tightly-Coupled Environments, this model was used for the performance evaluation of main features of the underlying conference control protocol, which was actually SCCS.

	Large-scale Publish Subscribe Inspired by my work on wireless sensing and by discussions with Pekka Nikander and others, a growing activity in my research focusses on the viability of publish-subscribe as a possible replacement for the IP send-recv model in the current Internet. Driven by the largely publish-subscribe nature of many existing and contemporary applications but also by considerations in the privacy and security space, my research focusses on issues to be addressed when considering such radical change in the overall Internet and its underlying paradigms. The issues revolve around questions on identity (both description as well as management), privacy and security (trust being central here), naming and addressing on internetworking layer, the nature of layers in a largely publish-subscribe world in the first place, scalability of solutions, and the impact on existing applications and services, to name only a few areas. My work in this area is largely conducted within the PSIRP project as well as in the Communications Futures Program at MIT, in particular within the Privacy & Security working group.
	The EIFFEL Initiative Less a research but more of a community effort, the EIFFEL initiative aims at establishing efforts for debate and interaction among the research community, initially in Europe and eventually beyond, in the space of the Future Internet. The initiative was created by the European Commission throughout July 2006 with the EIFFEL whitepaper being the outcome of the initial work, publically presented at the Future Internet workshop in Brussels in December 2006. Several follow-ups were created since then, one of which is the proposal for a Strategic Support Action within the EU's FP7 research framework with the aim to establish such stage for debate through a concrete set of meetings and workshops to be organized. Another activity within the ICST Society aims at complementing these activities with a stage that targets business strategists and policy makers. These activities, while currently largely focussed on Europe, are expected to grow internationally through appropriately connecting to similar activities, e.g., in the US.
	Mobile-Centric Wireless Sensing Started during my time at Nokia Research, wireless sensing is an important field of activity in my research, also connecting to the problem of large-scale publish-subscribe (see below). The NORS platform, being developed and eventually open-sourced during my time at Nokia Research, lays ground for a new form of participatory sensing that could potentially involve almost every end user directly through his/her mobile device being carried around. With that, end users directly become part of the provisioning system while still consuming the outcomes of the exercise as new forms of services, such as environmental warnings, traffic re-directs based on end user reports etc. The NORS work intended to combine best practises in sensor networking (using a simple yet efficient publish subscribe system) with modern smart phone technology, enabling the easy and fast integration of future sensors but also the fast developments of applications and services in the system. While the current implementation foresees a centralized application server on a Windows machine, future deployments can easily include servers directly on mobile phones of end users (the current practise of blocking phone-to-phone IP connections in mobile networks makes such deployment hardly likely and we therefore did not undergo the effort to port the server on a mobile platform). Future work in this space will not only focus on improvements to the platform, in particular in connection with the more general problem of large-scale publish subscribe (see below), but will also seek collaborations with academia to use the solution for their experiments on local sensing, federating the vast number of existing sensor deployments to a new form of experiments. The current open source availability of NORS makes such collaboration rather easy.
	Core-Edge Dynamics During my work on seamless mobility and applications in the Internet (see below), I encountered more and more the phenomenon of core-edge dynamics, which describes the movement of functionality between what we classically perceive as the "core" and the "edge" of the network. This movement, being caused by technological, economical, and regulatory forces, is recognized to have impacts on the current and future value chain of the telecommunication industry. In my work with MIT's Communications Futures Program (CFP), I used to co-chair the "Core-Edge Dynamics" working group (now called the Value Chain Dynamics working group), together with Prof. Charlie Fine from MIT Sloan. The working group is chartered with addressing the phenomenon of core-edge dynamics through methods of case studies, taxonomy definition, system model development, and derivation of possible future value chains. During regular small working group meetings and bi-annual large consortium meetings, industry partners such as France Telecom, Intel, British Telecom, and Nokia are working together with the faculty from MIT in this space. In addition to my work within this MIT consortium, I'm also engaged in the Mobile VCE consortium's Flexible Network programme which investigates socio-economic design approaches, based on work like that of CFP.

	Scalable Conferencing Control Service (SCCS) Due to my work in the area of group communication protocols (especially the T.120 and Internet stuff), I began my research for the design of a scalable conferencing control service (SCCS) for tightly-coupled environments, which uses an efficient resource management scheme and multicast for a better scalability in large scenarios. SCCS provides a service functionality similar to the ITU protocol suite (T.122, T.124). In contrast to existing protocols, SCCS supports complete reconfiguration of the conference tree topology to provide an optimization of the topology for reduction of response times, e.g. for the floor control. Currently, a complete service and protocol specification is available.
	ITU-based Collaborative Conferencing My T.120 research focus was on evaluation of the existing ITU-based conference control protocols for group communication in tightly-coupled environments, i.e., the standard family T.120 that is being used in H.32x conference systems. This standard provides generic functionalities for data conferencing applications. Several weaknesses of the standard were pointed out during this work, especially in the area of scalability in large scenarios. Additionally, a combination of T.120 and the distributed platform CORBA was studied and implemented to extend the T.120 by some useful features from a user's point of view.
	The Remote Paradigm A small comic... (not really research).