The market uptake of the 4th Generation networks is expected to support the increasing demand for wireless broadband services and ensure an enhanced mobile user experience. In this direction, the convergence of a wireless access network with an optical backhauling has been proposed. However, in such a converged architecture, the traditional fixed commitment of the backhaul resources does not prove to be as efficient, and novel dynamic schemes are required that consider both the needs of the base stations and the limitations of the passive optical network. This paper is concerned with the topic of resource allocation in two competing base stations that belong to different operators and share a common optical backhaul network infrastructure. An approach based on evolutionary game theory is proposed and employed, with a view to examining the interactions among the base stations and the passive optical network. Using the model of replicator dynamics, the proposed system design is proved to be asymptotically stable. In addition, this paper studies and reveals the extent to which time delay can have an impact on the proposed system design.

The recently deployed 4G access technology promises to satisfy the increasing demand of bandwidth consuming applications by providing high network capacity, low latency and seamless mobility. Towards this direction, concept solutions concerning the integration of wireless and optical networks have been proposed. However, the majority of these approaches assume the conventional fixed commitment of resources to the base stations, an inefficient and costly process, especially in case the Passive Optical Network (PON) belongs to a different operator. As a result, new, more dynamic backhaul resource allocation approaches are required. In this paper, the authors study the problem of committing resources of the backhaul network to a base station by employing evolutionary game theory in order to model the interactions between the subscribers and the base station. The asymptotic stability of the proposed scheme is proven under the replicator dynamics model. Finally, the impact of time delay in the proposed scheme is also investigated.

The present paper introduces the innovative concept of a new type of services, called ambient community services (ACS). The ACS concept utilizes information that resides in communities of mobile terminals, such as location, speed, sensor-related data or user-created multimedia content. After the collection, processing and filtering of these data, a number of innovative, heterogeneous value-added applications can be provided to the end-users, such as the provision of vehicular traffic conditions. ACS advances the social networking by allowing users to form cooperative, service-enabling communities. This paper includes a thorough description of the state-of- the-art, the proposed system architecture and communication flow, potential enabled applications, important implementation aspects, as well as future research activities.

This paper analyzes the concept of Anonymous Real-Time Mobile Community (ART-MC) services, which enables the real-time collection of information residing in a community of mobile terminals, which can then be processed and delivered to a service requesting terminal. An example application is the provision of real-time information concerning road-traffic conditions, based on the location and velocity of mobile terminals. The ART-MC concept requires the deployment of an appropriate software client at the terminal side, as well as the deployment of an ART-MC Server at the network side. The proposed architecture is presented and explained in detail. Anonymity and privacy issues are addressed, and an extensive analysis regarding scalability is given. Finally, additional example applications of the ART-MC concept are listed.

This paper deals with the design of systems that enable service provisioning in Beyond 3G (B3G) environments. The proposed systems are based on Service Enablers, entities that collect and process data from mobile terminals in order to form content for the provisioning of context-aware services. This content can be afterwards exploited by candidate applications. In this paper the main parameters that influence the design process are identified and the basic characteristics of service enablers are derived. Furthermore, we cite four basic operational structures according to our architecture and we present their special features. The MOTIVE system (MObile Terminal Information Value addEd Functionality) is used as a case study for the verification and validation of the proposed structures.

In this paper, we introduce a network-based approach for access and interface selection (AIS) in the context of resource management in heterogeneous wireless environments (UMTS, WLAN and DVB-T). We focus on the optimization of the resource utilization, while ensuring acceptable QoS provision to the end users. Our objective is to optimally manage the overall system resources and minimize the possibility of QoS handovers (non-mobility handovers). The adopted architecture applies to typical heterogeneous environments and network entities (access routers) are enhanced with extra functionalities. We propose an AIS algorithm that exploits the multihoming concept and globally manages network resources at both radio access and IP backbone networks. The algorithm can estimate near optimal solutions in real time and we also introduce a novel triggering policy. We present simulation results that demonstrate the advantages of our approach. System performance metrics, derived from the simulations, show minimum degradations in high load and congestion situations.

Abstract A high‐level technical survey of paging in mobile cellular communication networks is presented in this paper. We view paging as an optimal decision problem and explore different strategies based on sequential decisions. The examined schemes concentrate on different perspectives of the problem, depending on the type of decisions and the amount of information available or exploitable by the system. This approach provides a useful categorization and an easy conceptual basis for their theoretical investigation, necessary for the deployment of advanced paging algorithms. Because of its suggested generality, the discussed framework is also laid as reference for further research. As modern networks evolve, more emphasis will be given towards optimization in all aspects of a network system. The schemes presented greatly reduce paging costs and can be used in cooperation with known location update strategies to make part of a real network location management system. Copyright © 2006 John Wiley & Sons, Ltd.

This paper discusses the problem of user preference modelling in the context of next generation terminals operating in heterogeneous environments. It includes an approach to the definition, mathematical formulation and solution of this problem. Indicative results of the proposed solution method are presented in the framework of a real-life scenario, which simulates a day in the life of an ordinary user

This paper adopts the assumption that cellular, broadband fixed wireless access (BFWA), wireless local area networks (WLAN), and digital video broadcasting (DVB) systems can be co-operating components of a composite-radio infrastructure. It is believed that through the composite radio concept, operators will be enabled to offer efficient, in terms of cost and QoS, wireless access to broadband IP-based services. The exploitation of this infrastructure calls for the application of computational intelligence (CI) technologies for the development of appropriate, sophisticated service and network resource management functionality. In this context, this paper identifies and addresses the important problem of service configuration and distribution in a composite radio environment (SCD-CRE). The problem's objective is to determine the best way to accommodate a demand volume, with which the composite radio infrastructure is faced. The pro finds the QoS levels that can be offered, and the networks that can support the demand at the selected QoS levels. The paper includes a first approach to the definition, mathematical formulation, and solution of a version of the SCD-CRE problem. Results indicating some of the capabilities of the SCD-CRE are also presented. Further application fields for CI technologies are indicated, in the area of the necessary reconfiguration of the managed, radio and fixed, network segments.

High altitude platform stations (HAPS) are a new, promising means of providing International Mobile Telecommunications (IMT-2000). One of the potential problems of the system is the platform positional instability due to stratospheric winds. In this paper, we present a study of the effect of positional instability on the system level performance of a Universal Mobile Telecommunications System (UMTS) served by HAPS. Measurements of stratospheric winds at an altitude of 21 Km have been used to simulate the positional instability of a HAPS employing a propulsion station keeping mechanism. The platform instability model obtained gives input into a UMTS system level dynamic simulator and the effect of instability on the rate of soft handovers and system capacity is examined.

Abstract Data services like Web browsing, e‐mail and file transfer are becoming more and more popular in cellular systems. In contemporary systems like Global System for Mobile communications (GSM), data transfer has been circuit‐switched, that is, physical resources are allocated to a user for the entire call/session duration. However, this is inefficient in case of bursty traffic, where bursts are separated by long intervals of inactivity. This has been the main reason for the introduction of General Packet Radio Service (GPRS), which on the one hand acts as a mobile access network to the Internet, while on the other hand it enables the operator to offer a wide variety of value‐added services [Wireless Access Protocol (WAP) over GPRS, e/m‐banking, e/m‐commerce, push services, etc.] efficiently. However, in contemporary commercial implementations of GPRS the radio resource allocation algorithm does not take into account the Quality of Service (QoS)‐related service characteristics—although such information is exchanged between the terminal and the network—and consequently all service requests are treated the same way (‘best effort’). In this paper, we propose and evaluate via a simulation platform various Radio Resource Management (RRM) schemes capable of differentiating the handling of ‘service requests’ (in uplink and downlink), taking into account the GPRS‐related QoS parameters (precedence, reliability, delay, mean and peak throughput). The evaluation is performed for a range of voice (circuit‐switched) traffic loads, number of Transmit Receive eXchange (TRXs), offered data (packet‐switched) services characteristics, number of dedicated Packet Data Channels (PDCHs), and so on, taking into account the respective QoS requirements for both service types (circuit‐ and packet‐switched). Copyright © 2003 John Wiley & Sons, Ltd.

Abstract The essence of designing a good paging strategy is to incorporate the user mobility characteristics in a predictive mechanism that reduces the average paging cost with as little computational effort as possible. In this scope, we introduce a novel paging scheme based on the concept of reinforcement learning. Learning endows the paging mechanism with the predictive power necessary to determine a mobile terminal's position, without having to extract a location probability distribution for each specific user. The proposed algorithm is compared against a heuristic randomized learning strategy akin to reinforcement learning, that we invented for this purpose, and performs better than the case where no learning is used at all. It is shown that if the user normally moves only among a fraction of cells in the location area, significant savings can be achieved over the randomized strategy, without excessive time to train the network. Copyright © 2003 John Wiley & Sons, Ltd.

High altitude platform stations have been recently proposed as a new means of providing international mobile communications (IMT-2000). One critical issue that has not been resolved yet is the possibility of providing indoor services. This paper examines the penetration into buildings loss at high elevation angles. Two approaches are followed: An empirical model is presented and evaluated through comparison with two measurement campaigns. Furthermore, a 3-D ray-tracing tool was developed In order to simulate a specific environment of 11 buildings and take into account parameters not modeled by the empirical method, such as rooftop diffractions. Both approaches conclude that the penetration loss is an increasing function of the elevation angle, but the range of values obtained shows that indoor coverage is feasible.

The case of outdoor to indoor propagation prediction at high elevation angles has scarcely been addressed and no direct relationship between elevation angles and building penetration loss has been reported. High altitude platform stations (HAPS) - a new means of providing international mobile telephony (IMT-2000) - will be operating at high elevation angles. This paper examines the impact of high elevation angles in the propagation mechanism and penetration-into-buildings loss. A 3D ray-tracing software tool was developed in order to simulate a specific environment of 11 buildings and take into account parameters, such as diffraction from building edges and rooftops. This approach concludes that the penetration loss is an increasing function of the elevation angle.

This paper builds on the assumption that in the fourth generation (4G) wireless system context Universal Mobile Telecommunications System (UMTS), mobile broadband systems (MBS) and digital broadcasting systems (DBS) can be three co-operating components that enable wireless access to IP-based services. Managing the resources of this powerful infrastructure in an aggregate manner and multi-operator scenario is a complex task. This paper presents an approach to the overall UMTS, MBS and DBS network and service management problem. Key points addressed are the development of open interfaces with service provider mechanisms and the heterogeneous managed infrastructure, performance monitoring, joint optimization of the UMTS, MBS and DBS resources in accordance with the service provider requests and the changing with time environment conditions. The architecture of a corresponding UMTS, MBS and DBS network and service management platform is presented, in terms of logical blocks, implementation options and validation approach.

This paper adopts the assumption that cellular, Broadband Fixed Wireless Access (BFWA) and DVB systems can be co-operating components of a composite-radio infrastructure. It is believed that through the composite radio concept operators will be enabled to offer very efficient, in terms of cost and Quality of Service (QoS), wireless access to broadband IP-based services. The exploitation of this infrastructure requires new service and network resource management functionality. In this context, this paper addresses a problem called Traffic Distribution in a Composite Radio Environment (TD-CRE). The paper includes a first approach to the definition, mathematical formulation and solution of a version of the TD-CRE problem.

Advances in mobile devices' and networks' technology have set a challenging pace for all new proposals in the rapidly growing domain of mobile communications. The decade of the 90's brought a revolution in mobile computing. The explosion in sales of laptop PCs as well as personal digital assistants and cellular phones has marked the beginning of a new era in the users'/consumers' needs and demands from the network providers. Users of today opt not only for voice and multimedia applications but also for mobility. It is evident that high-speed wireless networks like WATM together with the use of IP are becoming more than an in vitro area of research.

In this short paper an approach to the ATM hierarchical (PNNI) routing issue is presented based on a simple algorithm that chooses a route for a connection request out of a predefined list of possible routes between a specific source-destination pair in a probabilistic way. A route fitness (cost) function is used to assign selection probabilities to every candidate path and arriving connection requests are routed independently according to these path probabilities. This cost function has been chosen in a way to achieve a successful trade-off between the use of minimum-hop routes and the application of the load-balancing concept. Moreover we show that the performance of the proposed algorithm and other probabilistic routing algorithms can be enhanced with the application of scaling techniques that are used in genetic algorithms (GAs) maximizing the network revenue. Simulation results over a wide range of uniform, time-varying and skewed loading conditions show the effectiveness of the proposed routing algorithm.

Position location of mobile terminals is one of the key and vital services for enhanced network performance. A variety of services may be offered when position location is deployed, such as emergency-call assistance, fleet management, location-based value added and multimedia services, navigation, stolen vehicle monitoring, improved network management and differential billing. Players in this area, nowadays and worldwide, are trying to integrate positioning techniques that will fulfill related FCC- and ETSI- localization recommendations, yet without exaggerating the network costs. Major European manufacturers have already developed positioning methods, yet none of them have been adopted in a cellular networking environment. In this contribution a novel technique is presented and its performance and compliance with the related standards is evaluated.

The success of third-generation mobile communication systems, e.g., UMTS, will depend on the quality of service (QoS) that the mobile users will perceive, and whether the QoS levels will be provided in a cost efficient manner. In this perspective, the importance of tools for "proper" planning of a mobile system becomes straightforward. In the context of this paper, we present such planning tools related to the design of future mobile communication systems. In addition, we present a platform that enables the assessment of the derived solutions by means of simulation.

It is envisaged that future cellular systems, e.g., UMTS, will consist of three network segments, namely, core, access, and intelligent. In the context of this paper, we define and solve some of the design problems related to the design of the access and intelligent network segments. In addition, we present a platform that enables the assessment of the derived solutions by means of simulation. Our aim is to analyse, formally state, and theoretically formulate these problems, and to provide a platform for assessing the efficiency of the solutions to these problems.

The deployment of DECT based mobile access systems urges for the development of interworking procedures between DECT and existing fixed networks. The B-ISDN infrastructure with its advanced signalling capabilities is an excellent choice to be used as a DECT local network. This paper proposes a reference configuration and an interworking specification for a hybrid DECT- B-ISDN mobile access system. It outlines a B-ISDN mobility control architecture capable of supporting full scale DECT mobility throughout the system and discusses in detail the B-ISDN user and control plane functionality which is necessary for the support of DECT mobility procedures over B-ISDN. The architecture and functionality described herein are implementation oriented and are aimed to support step by step integration of DECT mobile access systems in a core B-ISDN infrastructure.

One of the most central issues in third generation telecommunication systems is efficient spectrum utilisation. This objective has motivated extensive research in the area of channel allocation techniques. The basic version of the channel allocation problem is the following: given a set of channels, the cell structure and the load to be accommodated in each cell, find the optimum allocation of channels to cells, subject to the restrictions concerning the distance of cells, where the same channel can be used. This problem handles a traffic load that is fixed with time. We extend this formulation so as to include time variant traffic loads and, hence, to obtain efficient spectrum utilisation. We consider two approaches to this extension, which are differentiated by the fact that the first involves a total reconfiguration of the channel allocation, while the second only a partial reconfiguration. Both approaches are theoretically formulated and solved. Finally, we present results and draw subsequent conclusions.

Satellite systems in future mobile communications will be integrated with terrestrial cellular systems, aiming at worldwide coverage. We develop mobility models for the estimation of the average number of handovers per call in satellite systems. This parameter is crucial especially for low Earth orbit (LEO) systems, where the increased number of handovers affects the quality of service experienced by their users. The proposed mobility models, apart from providing indicative values for the number of handovers in geostationary and LEO systems, also provide means to identify the cell orientation, which minimizes this parameter in LEO systems.

A fundamental notion in third generation mobile systems is efficient spectrum utilisation. A first approach of the traffic adaptive spectrum allocation problem is the following: given the set of channels, the cell structure and the load to be accommodated in each cell, find the optimal allocation of channels to cells, subject to the restrictions arising from the minimum permissible distance of cells where the same channel can be used at the same time. This problem presupposes a traffic load that is fixed with time. In this paper we extend this scheme in order to include fluctuating traffic loads. This extended scheme is theoretically formulated, and found to be a difficult problem. Finally, a set of results is presented.

The efficiency and manageability of network management architectures, are based largely upon structuring principles, which make intensive use of concepts such as management domains and management policies. The paper discusses architectural aspects of management for the universal mobile telecommunication system (UMTS), and suggests a model for the structuring of the managed system into management domains, and the subsequent control of it through policies. Explicit statements are made concerning the representation of the policy structure. Furthermore, the assistance that standardized support managed objects can provide in policy implementation is examined. Finally, a schema for capturing the interrelations between policy objects is provided, assisting in this way the effective management of the policy structure.>

Numbering and addressing issues arising in the integrated broadband communication network (IBCN) for the support of the Universal Mobile Telecommunication System (UMTS) and Personal Telecommunication Service (PTS) are discussed. Mobile communications services will allow a user to roam within a network. Thus, there will be a need to identify several types of objects (terminals, network points of attachment, users, customers premises networks or CPN, etc.). The mobility properties of these objects will necessitate dynamic bindings between their addresses and names. The situation is further complicated because the mobility may be embedded. A mobile user may employ a mobile terminal in a mobile CPN. Therefore, in UMTS and PTS there is a need for dynamic binding of various identifiers with location information data. The exclusive use of personal telecommunication numbers (PTNs) as dialing numbers (DNs) is proposed in IBCN for UMTS and PTS. That is, PTNs will be used (during dialing) for making calls to mobile terminals, mobile users, and fixed subscribers. When the personal communication service is not provided, the DN corresponds to the terminal number of the equipment (fixed or mobile) of the called subscriber.>