Nancy Alonistioti

Cross-layer design proposals for wireless mobile networks: a survey and taxonomy

Third-generation (3G) and beyond 3G mobile communication systems must provide interoperability with the Internet, increase throughput for mobile devices, and optimize their operation for multimedia applications. The limited ability of traditional layered architectures to exploit the unique nature of wireless communication has fostered the introduction of cross-layer design solutions that allow optimized operation for mobile devices in the modern heterogeneous wireless environment. In this article we present the major cross-layer design solutions that handle such problems, and discuss cross-layer implementations with a focus on functional entities that support cross-layer processes and the respective signaling. In addition, we consider the associated architectural complexity and communication overhead they introduce. Furthermore, we point out the major open technical challenges in the cross-layer design research area. Finally, we conclude our article with a summary of cross-layer approaches developed thus far and provide directions for future work.

Adaptive charging accounting and billing system for the support of advanced business models for VAS provision in 3G systems

In the framework of the design of a flexible service provision platform for 3G systems and beyond, an integrated system for enabling advanced Charging, accounting and billing has been introduced. The CAB system is adaptive to VAS charging requirements and network/business environment concepts. Part of the system has been developed in the frame of IST-MOBIVAS project.

A framework for the deployment of self-managing and self-configuring components in autonomic environments

Over the last two decades, the advent of the Internet coupled with the diverse philosophy of networks, formed the basis for a pervasive computing environment. In the latter, the current trend is defined by the concept of autonomic computing and communications, which lies in the introduction of automated functions that enhance the intelligence of existing computing and communication systems. This concept forms a new paradigm of systems with selfware capabilities that will automatically adapt their behavior in relation to the configuration of the drastically changing environment and user preferences. In this context, this paper presents a generic architecture for the design and deployment of self-managing and self-configuring capabilities. In addition, it exploits the dynamic binding and replacement of components with autonomic capabilities. The feasibility aspects of the proposed framework are validated by means of a prototype that demonstrates the operation of plug and play solutions for an adaptable component-based protocol. Performance issues are also discussed

Toward spectrum sharing: opportunities and technical enablers

The vast increase in the number of mobile devices and their mobile traffic demands indicates the need for additional spectrum for cellular communications. Since it is not trivial to allocate exclusively new spectrum bands for cellular communications, it is imperative to improve the spectrum usage through new spectrum sharing mechanisms. This implies that the mobile network operators will have to cooperate and interact to cover the augmented traffic requirements. In this article we present a novel architectural framework that enables the mobile network operators and other spectrum license holders to exchange information about spectrum availability. We also present a novel spectrum sharing mechanism based on fuzzy logic to facilitate operators in selecting the most suitable spectrum to cover their needs.

Integrated generic architecture for flexible service provision to mobile users

The evolution of 3/sup rd/ generation mobile systems introduces a new era in advanced multimedia service provision to mobile users. The concepts of service adaptability, downloadability and network reconfigurability based on terminal and user profiles and capabilities are aspects to be considered in the context of future mobile systems and networks enabling new approaches in service provision. A generic architecture and functionality is presented for third party service registration, discovery, management and adaptable provision to mobile users.

A survey of dynamically adaptable protocol stacks

The continuous development of new networking standards over the last decade has resulted in an unprecedented proliferation of interfacing technologies and their associated protocol stacks. Never before was such a wide gamut of network architectures, protocol configurations and deployment options available to network designers. Alas, this significant increase in flexibility has come at the cost of an increased complexity in network management tasks, particularly with regard to the accommodation of performance requirements. Especially in mobile settings, this is due to the greater probability of unforeseen communication contexts that renders the efficient provisioning of multiple dissimilar protocol stacks a challenging task. To address this unpredictability, several approaches based on the dynamic adaptation of protocol stacks during runtime have been proposed and investigated over the years. This article surveys major research efforts dealing with the introduction of a dynamic adaptation capacity into protocol stack subsystems. To this end, we present the respective architectures with a focus on their functional entities and their particular mode of operation. Most importantly, we elaborate on the various design approaches to adaptability and the entailed degree of coupling between protocol stack-and layer-entities and their impact on resource allocation models. Furthermore, we classify these research efforts according to a taxonomy for non-monolithic protocol stacks and discuss design trade-offs inherent in each class. We conclude the article with a summary of the key design principles for adaptable protocol stack architectures.

To Reconfigure or Not to Reconfigure: Cognitive Mechanisms for Mobile Devices Decision Making

The vast proliferation in the continuously changing telecommunications environment of Next-Generation-Networks (NGNs) poses strict requirements for the dynamic adaptation of mobile devices according to the user needs, system resources and Radio Access Technology (RAT) availability. The reconfiguration concept emerges as a paradigm that offers an effective solution to this problem. On the other hand, the operation of mobile devices offering cognitive functionalities is characterized by a significant number of parameters, many of which are contradictive and cannot be simultaneously optimized, thus constituting reconfiguration a multi-objective optimization problem. This work proposes a solution to the problem, addressing efficient decision making mechanisms to avoid the ping-pong effect of multiple reconfigurations and exploiting fuzzy logic reasoning approach for terminal reconfiguration decision, focusing on resource management and protocol configuration.

An efficient RAT selection mechanism for 5G cellular networks

The design of an efficient radio access selection mechanism for 5G cellular networks is of paramount importance. Several proposals exist in the literature, but up to now the deployed systems are still using simple mechanisms mainly related to the evaluation of the RSS to make a handover decision. However, this is an inadequate solution for 5G networks. In this paper, we describe a novel multi-criteria handover scheme, we provide details on solutions for acquiring the necessary contextual information and we describe the algorithm to select the most appropriate RAT. Our solution is based on the use of fuzzy logic controllers for combining diverse inputs (such as a users mobility, the load of the candidate base stations etc.) The efficiency of our mechanism is evaluated through appropriate simulations. The results related to throughput, delay and the number of the executed handovers clearly show the merits of our proposal when compared to a well-established LTE handover algorithm.

Generic architecture and mechanisms for protocol reconfiguration

The next generation of wireless mobile communications termed beyond 3G (or 4G), will be based on a heterogeneous infrastructure that comprises different wireless networks in a complementary manner. Beyond 3G will introduce reconfiguration capabilities to flexibly and dynamically (i.e., during operation) adapt the wireless protocol stacks to better meet the ever-changing service requirements. For the dynamic reconfiguration of protocol stacks during runtime operation to become a practical capability of mobile communication systems, it is necessary to establish a software architecture that functionally supports reconfiguration. In the present paper, a generic architecture and respective mechanisms to achieve protocol stack and component based protocol layer reconfiguration are proposed.

Modeling and Performance Evaluation of Reconfiguration Decision Making in Heterogeneous Radio Network Environments

In heterogeneous radio network environments, the incorporation of dynamic adaptation capabilities in the protocol stack of mobile devices is an important challenge. In this direction, an appropriate model of the network decision-making process for mobile device adaptation is presented. Two main adaptation alternatives are assumed: (1) handover and (2) protocol reconfiguration. We consider two classes of mobile devices, i.e., reconfigurable and autonomous; the difference between them lies on the degree by which they support the decision-making functionality. An algorithmic framework for the management of the decision-making requests for reconfiguration or handovers is proposed. This work is based on the introduced metric of user satisfaction, which is based on the network response time for serving the decision-making requests. Such a framework is important for guiding the relocation of mobile terminals to achieve offloading. Furthermore, an analytical model for the computation of the user satisfaction is introduced, based on the work by Litoiu The analysis uses multiclass queuing networks to model the requests to the network as transactions among the system entities and compute the user satisfaction and the required parameters, e.g., network response time bounds. The obtained results show how the global bounds on the asymptotic network response time and throughput per class are affected by the number and frequency of reconfiguration decision requests. The analysis quantifies how the increase in the autonomicity level of mobile devices affects the network load and how to maximize the percentage of requests handled by the network, compared with the percentage of dropped requests. Moreover, our work reveals the degree of performance deterioration caused by increasing the autonomicity level in the management of requests.