Telektronikk 1.2008

This article serves as an introduction to this special issue of Telektronikk on network analysis. The introduction consists of three parts. In part 1 we give the motivation for studing networks as a general concept with wide applicability. We support this idea with a variety of example applications. Then in part 2 we offer an overview of many of the basic ideas and terms in modern network analysis, including where possible, clear quantitative definitions. The terms in part 2 are terms that turn up in a wide variety of fields where networks are important. Finally, in part 3 we give a “reader’s guide” to the other articles in this issue.

Finding paths between nodes is a basic enabling functionality in a communication network. At first glance, this may seem to be a trivial task. However, finding a path when no global information is available, is a challenge. Furthermore, paths should ensure an overall good utilisation of network resources, providing low delays and losses as well as the needed capacity between nodes. Paths should be altered as the network load and topology are changed, and paths should rapidly be recovered when network elements fail. The path management function has throughout the history of communication networks been designed to meet the prime requirement of the service provided by the network within what was technologically feasible. The future network will provide a multitude of services with, to some degree, conflicting requirements. At the same time inherent robustness and autonomy of network operation are of increasing importance. This invites new approaches relative to those used in the traditional communication network and the Internet. One such approach is to use swarm intelligence, where mobile agents explore, map and manage the network in a manner similar to the way insects, e.g. ants and bees, deal with their environment. With the above in mind, we have developed a distributed, robust and adaptive swarm intelligence system for dealing with path management in communication networks. The system is called the Cross Entropy Ant System (CEAS), and is based on increasing the probability of finding a (near) optimal solution by an increasingly focused random search. As a background for the system, this paper gives a brief discussion on path finding challenges and trade-offs. Following up is a description of CEAS where its robustness and adaptivity are demonstrated on a variety of case studies using different management strategies, like: shared backup path protection (SBPP), p-cycles, resource search under QoS constraints and adaptive paths with stochastic routing. This paper also includes a description of a running implementation of CEAS based on small home routers. The implementation demonstrates and visualises the inner workings of the method.

This article examines the way in which social networks operate within small groups. The study examines the social networks of teens and young adults. Groups of friends were recruited for the study and thus the unit of analysis is the group as opposed to the individual. The members of each group developed a contact diary (face to face, mobile voice, SMS, IM etc.) among the friendship group that also recorded their contacts with other "external" persons. The analysis shows the importance of copresence in the development of the groups and how mediated interaction can help to maintain and develop the group. The analysis also examines how different individuals played different roles within the groups.

The telecom industry is investing a lot of resources into traditional advertising despite the fact that many users often turn to their social environment for advice. Social relationships are one of the oldest media which are nowadays “empowered” by communication services. This makes it possible to take a look at users’ social context and gain insights into the referral behaviour of customers. In this exploratory study some results are presented which allow a new perspective on users and highlight the possibilities of social network analysis. Finally, it is stated that this knowledge is applicable for a new type of marketing and enhances the development of new services.

A promising and relatively new approach for studying distributed work groups is the application of social network techniques and theories (Ahuja and Carley 1999; Sparrowe, Liden et al. 2001; Cummings and Cross 2003; Hinds and McGrath 2006). A social network approach to distributed groups draws attention towards the social relations between the nodes in a network of distributed employees. Growth of new data coming out of on tele- and computer based traffic offers new opportunities to conduct such studies, and to analyse structures of collaboration patterns in distributed groups. Yet, the emerging field of network studies calls for a closer understanding of the relationship between patterns of mediated interaction and other more subjective relations, like trust and friendship. Based on a cognitive network approach (Krackhardt 1987; Corman and Scott 1994) this paper argues that observable interaction may be seen as indicative representations of a close relation, but not as confirmation. In particular in work settings, a high interaction level should not be seen as confirmative for close relationship, since much interaction is related to formal tasks. Interaction based ties should therefore be handled with care, and supplemented with other relational network indicators in network studies of distributed groups. The arguments are substantiated with results from a recent study of a group of distributed workers in an ICT company.

A growing number of firms create value by networking their customers. Classic examples include telecommunication operators, logistic services and banks. The primary innovations of such firms increase the connectivity of a network, that is who or what can be reached and the conductivity of a network, that is what can be exchanged. The article discusses exploration and exploitation in networking services. It has implications for how innovations are conceived, managed and measured.

This paper gives an overview of the current research program and some recent results in modelling of modern telecommunication environment obtained in the Department of Industrial Economics and Technology Management, NTNU. We concentrate on different strategic decision problems when it is necessary to take into account uncertainties in demand, technology and other important variables which characterize this rapidly changing environment. Besides, we look at cases that are characterized by the interaction of different agents engaged in relations of competition and collaboration. One such example deals with a quantitative evaluation of business models for collaborative provision of advanced mobile data services while another looks at the relations between network operators and service providers. Besides, we put our research focus in a wider perspective by presenting a survey of several promising modelling approaches of quantitative network analysis and formation. These include stochastic optimization, statistical mechanics of networks, network formation games and agent based computational economics. All of these research domains study complex interactive systems that are either explicit networks or can be described as such. The paper explores similarities, dissimilarities and linkages of these concepts including approaches on the border between these methodologies. Finally, implications for the research in telecommunications will be given.

The World Wide Web is a fascinating, useful, and important phenomenon of our time. It is also a graph – that is, a network, in which the nodes are Web pages and the links are one-way hyperlinks. This network view of the Web is basic to the challenging but practical endeavour of Web link analysis. Web link analysis takes the network of hyperlinks as a given input, and uses this information to give a quantitative score which estimates the importance of each page in the graph. In this article we give a pedagogical overview of the main ideas around, and mathematical approaches to Web link analysis.

Overlay applications are popular as they provide high-level functionality by masking the intrinsic complexity of the underlay network. However, overlays rely on the underlay to provide them with basic connectivity. Therefore, the intrinsic features of the underlay network determine the efficiency of the overlay. Accordingly, studying the interdependency of the overlay and underlay networks leads to a better understanding of overlay application behavior. We present a visualization-driven analysis technique for evaluating the overlay architecture with respect to the underlay, driven by the goal of overlay engineering. Using Gnutella as a case study, our analysis confirms that Gnutella topology differs from a randomly generated network and that there is an implicit correlation between the overlay and underlay topologies.

Terms and Acronyms used in Network Analysis.

Introduction to the Status section.

The main objective of the Radiocommunication Sector of the International Telecommunication Union (ITU-R) is to ensure rational, equitable, efficient and economical use of the radio-frequency spectrum by all radiocommunication services, including those using satellite orbits. ITU-R held its Radiocommunication Assembly (RA-07) in Geneva, 15-19 October 2007. A major outcome was the change of Study Group (SG) structure by reducing the number of SGs from seven to six, for example creating one large new SG (SG 5) on terrestrial services by merging fixed and mobile services, previously SGs 9 and 8, respectively. RA-07 also decided to include a sixth terrestrial air interface in the International Mobile Telecommunications (IMT) family by including the OFDMA TDD WMAN technology, a WiMAX derived technology. Mobile telecommunications were at centre stage at this RA as the Assembly adopted flexibility by choosing IMT as the root name for IMT collectively. IMT-2000 technologies as well as coming evolutions of the future IMT are now referred to as IMT. This had a major consequence for the following World Radiocommunication Conference (WRC-07) as spectrum both previously allocated to IMT-2000 and future allocations to IMT-Advanced in the Radio Regulations (RR) will now be collectively referred to as IMT. The ITU-R and its RAs play a major role for the development of global radiocommunications and make very important decisions for international telecommunications business.

ITU-R’s World Radiocommunication Conference (WRC) is the international forum for revising the Radio Regulations, the international treaty governing the use of the radio-frequency spectrum and satellite orbits. The WRC in 2007 (WRC-07) addressed the worldwide use of radio frequencies and sought solutions on how to exploit the limited resource of the radio frequency spectrum in the most rational and efficient way in order to meet the global demand for spectrum generated by rapid technological developments and growth in the information and communication technology (ICT) sector. The highlights of the WRC-07 included the issues regarding more spectrum for International Mobile Telecommunications (IMT), especially in the UHF-band and the C-band, and the revision of the regulatory procedures applicable to satellite services, including the Plan for fixed satellite services that provides spectrum and orbit resources to the Member States of the ITU. WRC-07 agreed on the following decisions of importance to telecommunications operators and vendor industry: • New allocations of additional spectrum for mobile services and IMT; • A revised framework of procedures for the fixed satellite service (FSS); • Resolution advocating the use of ICT in emergency and disaster relief including the prevention of climate change. The decisions of the WRC-07 in the form of Final Acts will be part of the international treaty “Radio Regulations” (RR).

New things generally fascinate people. This is especially true within the field of Information and Communications Technology (ICT). In science, it is good practice to make a literature search when starting a research project. This is a less common practice within ICT. Right now Identity Management (IdM) and Next Generation Network (NGN) are attracting great interest. Before developing directory like specifications within these areas, current works should be considered. It appears that the X.500 standard could play a major role here.

Terms and Acronyms used in the Status section.