Ronald Beaubrun

Mobility management in heterogeneous wireless networks

In heterogeneous wireless networks, mobile users are able to move from their home networks to different foreign networks while maintaining access capability to their subscribed services, which refers to global mobility. One of the key challenges in global mobility management is intersystem location management, which consists of keeping track of mobile users who roam into foreign networks. This paper presents an overview of mobility management in heterogeneous wireless networks and introduces a scheme which improves location management efficiency in terms of total signaling costs and intersystem paging delay. More specifically, cost reduction reaches about 50% when comparing the proposed architecture with conventional architectures.

Technological Developments and Socio-Economic Issues of Wireless Mobile Communications.

Abstract During the last 10 years, wireless communications can be considered as the fastest growing segment of telecommunications. In fact, mobile telephones have become an everyday accessory for hundreds of million people, and they are increasingly being used in the most developed and many developing countries in the world. Current forecasts indicate that demands for wireless access will exceed the number of fixed access lines by year 2010. This paper examines the technological developments, as well as the worldwide social-economic impacts of wireless mobile communications. More specifically, it gives an overview on the technological developments of wireless mobile communications, describes the evolution towards the next-generation systems, analyzes the reasons for the growth rate of subscribers, and the related social development. As a conclusion, it suggests several solutions in response to dangerous behaviour generated by wireless terminals.

Integration of Heterogeneous Wireless Access Networks

The development and proliferation of wireless and mobile technologies have revolutionized the world of communications [1]. Such technologies are evolving towards broadband information access across multiple networking platforms in order to provide ubiquitous availability of multimedia services and applications [2]. Recent broadband wireless access systems include wireless local area networks (WLAN), broadband fixed wireless access (metropolitan networks) and wireless personal area networks (WPAN), as well as the widely used mobile access technologies, such as General Packet Radio Service (GPRS), Wide Code Division Multiple Access (WCDMA), Enhanced Data Rate for Global Evolution (EDGE), 3G and Beyond 3G (B3G) communications systems, Worldwide Interoperability for Microwave Access (WiMAX), and Bluetooth [2–4]. These wireless access technologies have characteristics that perfectly complement each other [2]. Cellular systems and 3G provide wide coverage areas, full mobility and roaming, but traditionally offer low bandwidth connectivity and limited support for data traffic [1]. On the other hand, WLANs provide high data rate at low cost, but only within a limited area, whereas WiMAX can supply mobile broadband for anyone, anywhere, whatever the technology and access mode [4]. More specifically, WLANs are expected to provide access to IP-based services (including telephony and multimedia conferencing) at high data rates and reduced coverage in public and private areas [5]. In particular, current WLANs offer a bit rate of 54 Mbps with IEEE 802.11g in the 2.4 GHz frequency band [6]. In this context, several types of WLANs are emerging and become profusely used, allowing users to roam inside their home, enterprise or campus without interrupting their communication sessions. They are organized in form of hotspots, i.e. relatively small networks covering a particular location providing broadband and easy-to-use Internet access to their customers while supporting high traffic load. Classical hotspot examples are airports, hotels, dense urban areas, campuses, and private offices. Using hot-spots, providers can offer subscribers not only wide-area

A tabu search approach for assigning node Bs to switches in UMTS networks

This paper proposes a mathematical model for assigning Node Bs to switches in UMTS networks, as well as an implementation of the tabu search metaheuristic for solving such a problem. In this model, the overall problem is divided into two assignment sub-problems: the assignment of a set of Node Bs to a set of radio network controllers (RNCs), and the assignment of those RNC concurrently to a set of voice switches (MSCs: Mobile Switching Centers) and a set of data switches (SGSNs: Serving GPRS Support Nodes). In order to solve the overall assignment problem, the proposed implementation defines a number of moves which enable to efficiently explore the set of possible solutions. Computational results enable to identify the parameters that are able to reduce the costs of the obtained solutions, as such costs are relatively close to the estimated lower bounds and found in reasonable computational time.

Évaluation du délai dans un réseau mobile Ad hoc multi-services

Les réseaux mobiles ad hoc ou MANET (Mobile Ad hoc NETwork) sont constitués de terminaux mobiles qui peuvent se déplacer de manière aléatoire et à des vitesses quelconques. Cette mobilité des noeuds rend difficile l’évaluation du délai pris par les informations pour se rendre d’une source à une destination. Dans cet article, nous proposons une méthode d’évaluation du délai dans un réseau mobile ad hoc qui fournit les services les plus classiques, comme la voix, les messages textuels et la vidéo. Les résultats de simulation font ressortir l’impact de la mobilité, de l’intensité de trafic et du type de service offert sur le délai des informations.

An approach for managing global mobility and roaming in the next-generation wireless systems

In the Next-Generation (NG) wireless systems, mobile users (MUs) will be able to move across various heterogeneous networks while using their mobile terminals (MTs) to communicate. It has been proven that this global roaming freedom significantly increases the network-signaling traffic. Several schemes have been recently proposed to reduce such a traffic. This paper presents an efficient approach which uses a special gateway called Wireless INterworking Gateway (WING) to facilitate interoperability between heterogeneous subsystems of the NG wireless systems. Results reveal that such an approach significantly improves the network performance, in terms of generated signaling traffic and response time during the global roaming process.

An Approach for Cell Assignment in UMTS Networks

This paper proposes a new mathematical formulation to address the problem of cell assignment in UMTS network. To solve the problem, an adaptation of the tabu search metaheuristic is proposed. In this adaptation, applicable movements are well defined in order to efficiently explore the search space. Each movement has an associated gain that helps assess the degree of improvement of a current solution. Simulation results enable to evaluate the heuristic parameters that give the best solutions.

Blocking probability analysis in future wireless networks

This paper proposes to model each cell of future wireless networks as a G/G/c/c queueing system. As such a model has not been explicitly addressed in the literature, we apply maximum entropy principles to evaluate both traffic distribution and blocking probability within each cell. Analysis of numerical results enables to specify the conditions under which the system offers good quality of service in terms of blocking probability. More specifically, such an analysis reveals that coefficient of variation of call arrivals has more impact over the blocking probability than coefficient of variation of channel holding time.

Methods for Node Localization in Wireless Sensor Networks

This paper presents a brief review of the most important methods for node localization in Wireless Sensor Network (WSN). Among them are: Ad hoc Positioning System (APS), Anchor-Free Localization (AFL) and MoteTrack. Such methods may achieve good accuracy at the cost of extra hardware which needs to be present at each network node.

A middleware architecture for disseminating delay-constrained information in wireless sensor networks

Data dissemination is a process where information is transmitted towards different destinations. In order to prevent accidents, coordinate rescue operations and warn people about critical events, this process imposes end-to-end delay constraints. Accordingly, the delay from each source to each destination should be monitored. For this purpose, a middleware is required between the network and the applications, offering the tracking capabilities of disseminated information. In this paper, we propose a middleware architecture for disseminating delay-constrained information in Wireless Sensor Networks (WSNs). In order to evaluate the feasibility of such architecture, a proof of concept of a real scenario is implemented. For performance evaluation, the end-to-end delay and the percentage of success related to the disseminated information are analyzed. Such analysis reveals that the middleware offers a percentage of success close to 98%, which is highly superior to the success of individual resources, such as Short Message Services (SMS), emailing and twitter.