Sebastiano Trigila

Mobility in long-term service architectures and distributed platforms

This article focuses on the convergence of two technical streams of current interest: (1) service architectures as an innovative, integrated solution to the problems addressed by intelligent networks and telecommunications management networks; and (2) mobile communications systems and related software for their control and management. Its main objectives are to: (a) introduce the state of the art in long-term service architecture (SA); (b) identify the potential benefits of using SA concepts in the design and deployment of mobile communications systems; (c) indicate principles for inclusion of personal and terminal mobility aspects in the SA; and (d) consider the implications of mobility on the distributed processing environment underlying a set of services built according to the SA. The technical content of the article partly reflects work being carried out in international cooperative fora, particularly within the global initiative TINA and selected projects of the European research program ACTS. However, most views expressed here are the result of original evaluation and synthesis carried out by the authors. The timing validity of the article is in the medium to long term, since it targets the development and deployment process of systems that may not be in operation until the turn of the century.

Converging towards a timed LOTOS standard

Abstract Several ideas and proposals for an extension of the LOTOS ISO standard meant to support the specification of time parameters and time-dependent behaviours have appeared in the last few years. Some general requirements that such an extension should meet are identified, and a number of specific design options are discussed. Corresponding design decisions are then taken and motivated, leading to the definition of a Timed Basic LOTOS which attempts to promote convergence among the different existing proposals.

Using CORBA to support terminal mobility

Nomadicity is quite a new challenge for computing and communication technologies. Some of the key issues in the field are: the impact of nomadicity on client server interaction; how to support terminal mobility, and how to cope with the unique performance characteristics of wireless access. The first issue focuses on the question of whether the computational viewpoint client server interaction mechanisms for feed environments remain valid in mobile environments. The other two issues are related to the engineering aspect of dealing with mobile routing and the unpredictable performance and reliability of wireless networks, generally orders of magnitude below those of wired networks. We show a novel way to deal with these issues in a CORBA based distributed processing environment. Object technology-CORBA, in particular-is already mature. Today CORBA provides a software execution and development environment that simplifies distributed computing and application integration. The main stream of CORBA based solutions is targeted to LAN based applications relying on (quite) fast and reliable connections. We show that the CORBA 2.0 specification also provides the means to support nomadic computing. We demonstrate how the CORBA 2.0 interoperability architecture, together with some CORBAServices (Common Object Service Specifications), can be used to provide seamless support to terminal mobility and communication through slow wireless connections. The corner stones of our solution are mediated bridges, and an Environment Specific Inter-ORE Protocol (ESIOP) tailored for wireless networks.

Service architectures and service creation for integrated broadband communications

RACE is a collaborative, pre-competitive R&D programme, partially funded by the European Union. The programme comprises a number of projects involving participants from all major European telecommunications sectors. The focus is IBC, a concept which encompasses broadband fixed and mobile networks, broadcasting and multimedia communication services. The goal is to further the development and deployment of IBC in Europe, eventually forming a complete information and communication system available to, and usable by, all. RACE projects are grouped in Project Lines. Relevant to this paper is an area called Intelligence in Services and Networks (IS&N), which deals with the technologies required to engineer the next generation of the intelligent network or long term IN. Within the IS&N area, a number of projects have dealt with service engineering. This paper will present highlights of the vision and results developed by some RACE projects in the field of service engineering.

A service architecture for fixed and mobile convergence

This paper discusses an architecture to cope with the technical complexity of the global system resulting from the world-wide interworking of mobile and fixed networks of different technologies, for the provision of multimedia services, in a liberalised and deregulated environment. The architecture represents the convergence of two frameworks that had progressed independently until the mid 1990s: (a) service architectures for a global information infrastructure; and (b) mobile communications systems. The need for the convergence of mobile and fixed networks at service control and management level is a key issue in the telecommunications environment. The existence of a generic service layer spanning a set of heterogeneous networks (fixed and wireless) promises several advantages for greater flexibility and efficiency in service development and deployment, compared to those obtainable with network-specific service creation practice. The TINA-C has established an architecture that has the potential and momentum to respond to such challenges. However, several adjustments and refinements in both the TINA network and services architectures appear necessary when addressing mobility. The approach presented here was envisaged by the EC/ACTS research project DOLMEN, which took as a basis the TINA architecture and enhanced it in the perspective of world-wide mobility service provisioning in a multi-provider environment. The paper shows how requirements stemming from personal mobility and terminal mobility are reflected in relevant changes and extensions of TINA, namely: a new Business Model (including also the role of Terminal Provider), two new computational components (User Agent Home and User Agent Visited), the concept of Retailer Federation, new ways to model and manage terminal mobility at CORBA level (the DPE model chosen by TINA) by means of ad-hoc defined interoperability bridges and new object referencing schemes, and finally, suitable models to represent handover in the TINA Network Resource Architecture.

Concurrent system analysis using Petri nets: an optimized algorithm for finding net invariants

Abstract Analysis of net invariants has proved to be a powerful technique for investigating properties of concurrent systems modelled by generalized Petri nets. Unfortunately, the best known algorithms for invariant search have an exponential cost, leading in many real cases to unacceptable consumption of computing resources. An algorithm is presented here which, although still exponentially complex, introduces significant optimizations that are meant to considerably extend the practical feasibility of invariant analysis. After a short summary of the invariant method and a brief recall of existing algorithms, the features of the new algorithm are developed and proved. The optimizations proposed here could be successfully taken into account when designing new algorithms for high level Petri nets.

Personal mobility aspects in service architectures: extensions to TINA

Abstract Telecommunications Information Networking Architecture (TINA) is a proposal elaborated in the period 1993–97 by major corporate organisations worldwide, in the fields of both telecommunications and information technology, towards standardisation of software interfaces and components for control and management of telecommunications services. Among these, particular relevance is played by personal mobility applications that should provide users with the capability to access services from any terminal in any place. However, full support of personal mobility requires enhancements to the TINA concepts and models. In this paper, an approach is presented towards full incorporation, in TINA, of personal mobility requirements laid down in the ITU-T UPT standards. Specifically, we discuss how personal mobility requirements can be reflected on the TINA Business Model and the TINA Service Architecture. In particular, a new business role and the concept of “Retailer Federation” are presented as the means to obtain ubiquitous worldwide service provisioning to roaming users in a multi-provider environment.

Mobility in TINA

The need to advance the frontiers of open service provision and open network management beyond what is actually achievable with IN and TMN was the main driver of the TINA-C initiative, that began in 1993, after precursory work done within the European Programme RACE (in particular with Projects ROSA and Cassiopeia) and within Bellcore (in particular with their AIN, Advanced Intelligent Network). TINA-C laid down a number of principles at the beginning of its work.

Beyond the TINA Lesson: Distributed Processing for Integrated Fixed and Mobile Communications

A major keyword of the Information and Communication Technology progress in the Nineties is convergence: integrated provision of telecommunications and information services, integrated management and control, provision of services above an infrastructure resulting from the interconnection of various network types, ubiquitous offering of fixed and mobile services. This paper deals with a technological enabler of convergence, namely network programmability, on a geographical scale and, eventually, on a global, worldwide level. Nowadays, the main convergence problem appears to be UMTS, defined by somebody as ”the fusion of Fixed and Mobile Networking”. The distributed processing paradigm of TINA as an enabler of fixed and mobile convergence is analyzed, through a timeline summarizing more than a decade of research and development. Pre-TINA solutions and post-TINA solutions are included in this timeline.