Georgia Dede

Evaluation of Optical Wireless Technologies in Home Networking: An Analytical Hierarchy Process Approach

Home networks (HNs) will play a crucial role in achieving broadband service delivery and enabling the future Internet. Optical wireless (OW) is a promising technology for realizing this vision. This paper presents the main results of a roadmapping effort undertaken within the project ICT-OMEGA concerning the potential of OW HNs. Using the framework of the analytic hierarchy process, five different optical home networking scenarios are identified and ranked. Within this framework, the importance of several economic, social and performance criteria is also evaluated. The obtained results are justified taking into account the technical particularities of each architecture. A sensitivity analysis is also performed to further elaborate on the results.

Convergence properties and practical estimation of the probability of rank reversal in pairwise comparisons for multi-criteria decision making problems

Abstract In this paper, we address the impact of uncertainty introduced when the experts complete pairwise comparison matrices, in the context of multi-criteria decision making. We first discuss how uncertainty can be quantified and modeled and then show how the probability of rank reversal scales with the number of experts. We consider the impact of various aspects which may affect the estimation of probability of rank reversal in the context of pairwise comparisons, such as the uncertainty level, alternative preference scales and different weight estimation methods. We also consider the case where the comparisons are carried out in a fuzzy manner. It is shown that in most circumstances, augmenting the size of the expert group beyond 15 produces a small change in the probability of rank reversal. We next address the issue of how this probability can be estimated in practice, from information gathered simply from the comparison matrices of a single expert group. We propose and validate a scheme which yields an estimate for the probability of rank reversal and test the applicability of this scheme under various conditions. The framework discussed in the paper can allow decision makers to correctly choose the number of experts participating in a pairwise comparison and obtain an estimate of the credibility of the outcome.

Decision Support Convergence properties and practical estimation of the probability of rank reversal in pairwise comparisons for multi-criteria decision making problems

Abstract In this paper, we address the impact of uncertainty introduced when the experts complete pairwise comparison matrices, in the context of multi-criteria decision making. We first discuss how uncertainty can be quantified and modeled and then show how the probability of rank reversal scales with the number of experts. We consider the impact of various aspects which may affect the estimation of probability of rank reversal in the context of pairwise comparisons, such as the uncertainty level, alternative preference scales and different weight estimation methods. We also consider the case where the comparisons are carried out in a fuzzy manner. It is shown that in most circumstances, augmenting the size of the expert group beyond 15 produces a small change in the probability of rank reversal. We next address the issue of how this probability can be estimated in practice, from information gathered simply from the comparison matrices of a single expert group. We propose and validate a scheme which yields an estimate for the probability of rank reversal and test the applicability of this scheme under various conditions. The framework discussed in the paper can allow decision makers to correctly choose the number of experts participating in a pairwise comparison and obtain an estimate of the credibility of the outcome.

Impact of cross-national diffusion process in telecommunications demand forecasting

New product diffusion process studies focus mainly on estimating the adoption rate of the product, within the boundaries of the targeted market. However, and especially for high technology and telecommunications products, it is very likely the case that products or services are introduced simultaneously into a number of market segments, a fact that it is rarely taken into account. Thus, the effect of market and population interaction, and the consequent co-influence in the diffusion rates is not considered. This work focuses on developing and evaluating a pertinent methodology, so as to capture this cross-national interaction influence in the diffusion process.

Towards a Roadmap for Future Home Networking Systems: An Analytical Hierarchy Process Approach

Home Networking Systems (HNS) play a crucial role in achieving broadband service delivery to end users and are quickly becoming the next arena for telecom operators and companies. This emphasizes the need for a technology roadmap in order to address several key issues associated with the deployment of these systems. The present paper presents the results of the European project ICT-OMEGA road mapping effort for future HNS focusing on the most indicative and critical function, namely that of network extension. Taking into account the various social, economic and technological factors, three alternative technologies, namely the 802.11n, 60 GHz and Power Line Communications (PLC) have been ranked, using the Analytic Hierarchy Process (AHP). Based on a number of expert surveys, the technology value of each solution is calculated. The results indicate that PLC possesses the largest potential for delivering broadband services in the home environment but also underlines the need for hybrid solutions. The results also reveal various crucial aspects of HNS deployment which are related to current research and standardization activities. A sensitivity analysis is also performed to ascertain the reliability of the results.

Theoretical estimation of the probability of weight rank reversal in pairwise comparisons

Pairwise comparison is a key component in multi-criteria decision making. The probability of rank reversal is a useful measure for evaluating the impact of uncertainty on the final outcome. In the context of this paper the type of uncertainty considered is related to the fact that experts have different opinions or that they may perform inconsistent pairwise comparisons. We provide a theoretical model for estimating the probability of the consequent rank reversal using the multivariate normal cumulative distribution function. The model is applied to two alternative weight extraction methods frequently used in the literature: the geometric mean and the eigenvalue method. We introduce a reasonable framework for incorporating uncertainty in the decision making process and calculate the mean value and cross-correlation of the average weights which are required in the application of the model. The theoretical results are compared against numerical simulations and a very good agreement is observed. We further show how our model can be extended in applications of a full multi-criteria decision making analysis, such as the analytic hierarchy process. We also discuss how the theoretical model can be used in practice where the statistical properties of the uncertainty-induced perturbations are unknown and the only information provided by the pairwise comparison matrices of a small group of experts. The methodology presented here can be used to extend the pairwise comparison framework in order to provide some information on the credibility of its outcome.

Photonic Technologies for Next Generation Home and Office Networks

In this paper, we discuss how wireline and wireless photonic technologies can be used to support high bandwidth connections inside a home or office setting. We first present a set of requirements that photonic home networks must meet in order to provide a viable alternative. These requirements are somewhat different than what photonic technologies had to meet in long-haul and metropolitan area networks. We then discuss enabling technologies for the optical home network, including optical wireless, visible light communications and plastic optical fibers. We also present some basic home networking network architectures that take advantage of multiple technologies in order to provide inter and intra-room connectivity. Some concluding remarks are given and an outlook for optical home technologies is briefly outlined.