George Karetsos

Mobile and wireless communications are moving towards a new era that will be characterized by the seamless collaboration of heterogeneous systems, the need for high speed communications while on the move and for advanced services with quality guarantees. Recent market research studies show that most of the traffic in the future wireless networks will be produced by mobile multimedia services which are expected to proliferate by the year 2010. On the other hand mobile and wireless communications technology is becoming more and more important in developing countries where people demand fast deployment and low cost for broadband wireless internet services. The objective of this volume is to gather research and development on topics shaping the fourth generation (4G) in mobile and wireless communications and reveal the key trends and enabling technologies for 4G.

Despite frustrating customers and loss of revenue for telecommunications providers, cellular network congestion has remained a problem for which few solutions have been found. Covering GSM, GPRS, UMTS and beyond 3G systems, this practical book breaks new ground by providing you with proven techniques for decreasing blocking and dropped call rate due to network congestion. Using real measurements, this book clearly shows you that the maximum traffic that can be accommodated in a wireless network is not a constant value and varies significantly.

This paper analyses the information brokerage service business environment and proposes a suitable enterprise model. The model definition was made according to the ODP enterprise viewpoint syntax and semantics and provides a modular framework within which the various components of the system are functioning for supporting its potential users in identifying and performing their tasks. The enterprise specification of the brokerage service starts from the definition of the actors involved in the service provisioning scenarios (End-Users, Brokerage Service Provider Retailer, Content Providers, Information Service Providers, Network Providers), their respective domains, their roles and relationships. A set of Brokerage Service scenarios is presented using the concepts defined in the proposed model

Next generation network nodes are required to function within heterogeneous network environments, where new services and protocols are rapidly deployed on demand. In such emerging environments, traditional node architectures that offer a predetermined and preloaded set of services, are increasingly incapable of coping with these new requirements. Accordingly, there is a need for new node architectures that offer higher degrees of flexibility measured by their capability to extend the functionality of the node and change its behaviour on demand. This paper makes use of programmable and active network technologies as developed during the FAIN project, to present a novel secure active node architecture, called the FAIN node architecture, capable of supporting virtual environments (VEs) for the allocation of the required amount of resources in which new services are dynamically deployed together with their entire execution environments (EEs). To this end, multiple VEs and services run simultaneously and interact securely with the node resources and mechanisms through open interfaces and the FAIN node management framework. We also present the implementation of the FAIN node architecture and two case studies that demonstrate its extensibility aspects and novel features.

CiteSeerX - Document Details (Isaac Councill, Lee Giles): This paper focuses on the use of mobile agents for the management of IP and access networks. In particular, configuration management and QoS enforcement methods will be presented together with the description of the ...

Cognitive radio is considered as one of the main enablers for provisioning dynamic and flexible spectrum/channel allocation in wireless communications. On the other hand several physical layer mechanisms such as adaptive modulation, multiple-input multiple output systems, advanced channel coding and/or combinations of them enhance the capacity of wireless networks. However little effort has been put till now in studying the performance gains of physical layer mechanisms with the presence of cognition capabilities. The incorporation of cognitive mechanisms demands more detailed studies for assessing the impact on the spectral efficiency. To this direction, cross-layer combination of such a physical layer with upper layers should be also considered as a case study in a cognitive wireless environment. In this work we present a study on the spectral efficiency of adaptive modulation and coding which is one of the most promising schemes of applying cognitive radio at the physical layer. Besides, we study a cross-layer combination of adaptive modulation with upper layers in the same cognitive context. We prove that the performance gain of cognitive radio over such a physical layer is not negligible.

Page 1. A mobile agent enabled wireless sensor network for river water monitoring Theodore Kotsilieris Department of Health & Welfare Units Administration Technological Educational Institute of Kalamata Kalamata, Greece tkots@teikal.gr ...

... Angelos Michalas' , Theodore Kotsilieris', Stylianos Kalogeropoulos', George Karetsos', Moshe Sidi2 and Vassilios Loumos ... [4] S. Waldbusser, " Remote Network Monitoring Management Information Base", RMON" RFC 28 19, May 2000. ...

Abstract - Nowadays we witness a growing interest for the efficient management of the QoS delivered by the service providers to the Internet users and the usage of SLAs. In such an environment the need to maximise customer satisfaction and reliability and consequently, the deriving ...

Supporting quality of service (QoS) over the Internet is a very important issue and many mechanisms have already been devised or are under way towards achieving this goal. One of the most important approaches is the so-called Differentiated Services (DiffServ) architecture, which provides a scalable mechanism for QoS support in a TCP/IP network. The main concept underlying DiffServ is the aggregation of traffic flows at an ingress (or egress) point of a network and the marking of the IP packets of each traffic flow according to several classification criteria. Diffserv is classified under two taxonomies: the absolute and the relative. In absolute DiffServ architecture, an admission control scheme is utilized to provide QoS as absolute bounds of specific QoS parameters. The relative DiffServ model offers also QoS guarantees per class but in reference to the guarantees given to the other classes defined. In this paper, relative proportional delay differentiation is achieved based on class-based queueing (CBQ) scheduler. Specifically, the service rates allocated to the classes of a CBQ scheduler are frequently adjusted in order to obtain relative delay spacing among them. The model presented can also be exploited in order to meet absolute delay constraints in conjunction with relative delay differentiation provision. Simulation experiments verify that our model can attain relative as well as absolute delay differentiation provided that the preconditions posed are satisfied.

Over the last few years wireless local area networking (WLAN) has become a very important technology that offers high-speed communication services to mobile users in indoor environments. WLAN technology offers some very attractive characteristics such as high data rates, increased QoS capabilities and low installation costs that made many professionals claim that it will be the main opponent of IMT-2000, despite the enormous effort spent for the specification and implementation of 3G systems. However, WLAN present also many important constraints mainly related to their restricted coverage capabilities. On the other hand 3G systems are deployed gradually and carefully since their business prospects are not yet validated and is expected that 2G and 2G+ cellular systems will continue to play an important role for at least five more years. Thus our today’s wireless networking environment is in fact a conglomeration of all these technologies for which there is a strong need for cooperation. In this paper we describe a heterogeneous wireless networking environment, together with its features and user requirements. We explain the importance of the WLAN existence and we describe a framework and a system architecture that supports seamless integration of WLAN in heterogeneous cellular networking environments focusing on supporting efficient resource provision and management.

In this work we present an approach for enhancing the performance of a Mobile Agent based Network Management System by monitoring and controlling the communication paths between the network management applications and the mobile agents. Mobile Agent Technology (MAT) seems to be a promising way for achieving flexible and decentrahzed Network Management. A system independent Mobile Agent platform is used in order to control the roaming and downloading of the required management code, in the form of mobile agents, onto the network devices. A management task such as the configuration of a specific QoS parameter related to a particular apphcation may require that a MA should visit up to hundreds of network nodes. Its is proved that the time needed for the execution of a Network Management task is decreased if the mobile agent's traveling path is computed by taking into account the load on each target node.

Congestion management in cellular networks is of prime importance for the mobile network operators of present and future generations. Nowadays cellular operators utilize improved planning techniques for enhanced capacity management, but on the other hand the number of mobile subscribers rapidly increases and additionally, new data-technologies for wireless access add extra traffic to the already overloaded networks, often causing serious problems to their performance. In this paper, we present a resource management system for increasing the efficiency of 2G and 2.5G cellular networks especially during overloading periods through the introduction of innovative extra elements. For validating the system's behavior, a set of trials have been performed focusing on alleviating both voice and data congestion problems. The results of these trials show important improvements on the network's capacity availability when the presented system intervenes.

Self-adaptation to changes in network context or self-contextual functionality refers to the capability of network nodes to dynamically reconfigure themselves in changing heterogeneous networking environments, in which new services and protocols will be rapidly created and deployed on demand. A novel programmable architecture, called the Future Active IP Networks (FAIN) node, is presented to address the described issues.

This paper describes an envisioned technology roadmap for the development of mobile and wireless communications until the year 2010. The roadmap description is based on a 3-years study (2001–2004) and monitoring of the technological developments of characteristically chosen mobile and wireless communication areas. The final definition of the technology roadmap was based on selected areas of high value that the authors consider as the corner aspects of the evolution of mobile communications. Two main groups of areas were defined and analyzed from a technological and from a service perspective. From technological perspective the areas of high research interest include radio technologies with effect on spectrum use, access and radio interface technologies, and technologies related to mobile terminals. From service perspective, we considered interactive broadcasting, location technologies and location based services (LBS) and personalization of services. The paper identifies the open issues to be solved to realize the future of wireless communications and describes the enabling technologies for next generation communications. It identifies the technology and non-technology barriers to development, deployment, as well as guidelines for the use of technology. Finally, a visionary scenario is described to illustrate the necessary evolution of the value chain for the successful deployment of any new service or technology.

One of the most important initial steps, inherent in the planning procedure of cellular networks, is their segmentation in operational parts that is performed at different levels corresponding to the hierarchy and topology of the network. The major goal of this procedure is the efficient system’s deployment and management of the distributed segmented parts while minimizing the signaling overhead in the network. As we show here it can take place even during the operational phase of the network when certain shortcomings appear. In this work we present an approach based on graph theory for the segmentation of cellular networks at the Base Station Controller (BSC) level that achieves a significant increase in the network’s performance. In particular, with the proposed method, both the handover attempts when a mobile station is moving to a cell belonging to a different BSC as well as the corresponding handover failure rate are decreased significantly, allowing for a continuous network upgrade.

In future wireless networks multimedia applications are expected to finally dominate the overall traffic volume. Shared channels are more suitable for the transmission of this type of traffic, as they are able to periodically adjust their transmission rate. In this paper, we introduce a cross-layer framework for WCDMA based networks which aims to make the packet scheduling procedure more efficient. In addition to that, we further propose a traffic scheduling scheme which serves the connections not only according to their delay sensitivity, but also according to the predicted state of their wireless channel. The efficiency of the proposed scheme, in terms of average packet delay and channel utilization is verified via simulations.

Abstract Handover is a critical feature in cellular systems and therefore handover algorithms are under extensive research. Problems in handover algorithm or its parameters may lead into call drops with a direct effect on user satisfaction. This is particularly critical for 3G ...

In the previous years the number of mobile Internet subscribers has grown up, resulting in an increased demand for a reliable mobile IP protocol, that supports a variety of services, such as access to intranet, fixed IP address and the ability to receive multicast datagrams. The transition from IPv4 to IPv6 has led to a more stable protocol that fulfils many of the requirements for supporting mobile users. Active networks is a new area of research that claims to exploit the available network resources in a more efficient way. In this paper we study the application of Mobile IP over an active networking environment, considering the limitations and requirements for a reliable network

Admission control plays a very important role in wireless systems, as it is one of the basic mechanisms for ensuring the quality of service offered to users. Based on the available network resources, it estimates the impact of adding or dropping a new session request. In both 2G and 3G systems, admission control refers to a single network. As we are moving towards heterogeneous wireless networks referred to as systems beyond 3G or 4G, admission control will need to deal with many heterogeneous networks and admit new sessions to a network that is most appropriate to supply the requested QoS. In this article we present the fundamentals of access-network-based admission control, an overview of the existing admission control algorithms for 2G and 3G networks, and finally give the design of a new admission control algorithm suitable for future 4G networks and specifically influenced by the objectives of the European WINNER project.

A joint optimal power allocation and sensing threshold selection for capacity maximisation at the secondary user (SU) in spectrum sharing (SS) cognitive radio networks (CRNs) is proposed. Hence, both optimal power allocation and spectrum sensing is considered in the SS CRNs model. The obtained results show that such a joint optimal selection improves the performance of the SU by maximising its capacity.