Vol. 65, n° 3-4, March-April 2010
Content available on Springerlink

Guest editors
Markus Fiedler, Blekinge Institute of Technology, Sweden
Helmut Hlavacs, University of Vienna, Austria
Klaus Hackbarth, University of Cantabria, Spain
Patrik Arlos, Blekinge Institute of Techology, Sweden

Foreword

Markus Fiedler, Helmut Hlavacs, Klaus Hackbarth, Patrick Arlos

Application of cost models over traffic dimensioning with QoS restrictions

Alberto E. García & Laura Rodríguez de Lope & Klaus D. Hackbarth

Telematic Engineering Group, University of Cantabria, Santander, Spain

Abstract Network operators and Internet service providers are offering “Triple Play” products integrating services with different quality of service (QoS) requirements. The provision of QoS guarantees implies the revision of current dimensioning methods and consequences for costing and pricing. This paper proposes a cost model which considers QoS parameters, based on the Total Element Long Run Incremental Cost (TELRIC) model, calculating the cost of a network element and distributing it over the different services whose traffic uses it, taking into account the QoS requirements of each service. For this purpose, three traffic engineering methods are analyzed: complete traffic aggregation by “Over-engineering,” complete traffic segregation by separated virtual tunnels, and partial traffic aggregation by priority queuing. As an example, the cost model is applied to the connection in a Next Generation Network aggregation network for estimating the influence of QoS and traffic engineering on the cost estimation under the TELRIC model

Keywords NGN . TELRIC . Costing . QoS . Traffic Engineering

An economic model for pricing tiered network services

Qian Lv · George N. Rouskas

Department of Computer Science, North Carolina State University, Raleigh, NC 27695-8206, USA

Abstract We consider networks offering tiered services and corresponding price structures, a model that has become prevalent in practice. We develop an economic model for such networks and make contributions in two important areas. First, we formulate the problem of selecting the service tiers from three perspectives: one that considers the users’ interests only, one that considers only the service provider’s interests, and one that considers both simultaneously, i.e., the interests of society as a whole. We also present an approximate yet accurate and efficient solution approach for tackling these nonlinear programming problems. Given the set of (near-) optimal service tiers, we then employ gametheoretic techniques to find an optimal price for each service tier that strikes a balance between the conflicting objectives of users and service provider. This work provides a theoretical framework for reasoning about and pricing Internet tiered services, as well as a practical toolset for network providers to develop customized menus of service offerings. Our results also indicate that tiering solutions currently adopted by ISPs perform poorly both for the providers and society overall.

Keywords Tiered services · Price structure · Economic model

Optimal pricing strategy with compensation when QoS is not satisfied

Bruno Tuffin¹ · Hélène Le Cadre² · Mustapha Bouhtou²

¹ INRIA Rennes—Bretagne Atlantique, Campus Universitaire de Beaulieu, 35042 Rennes Cedex, France
² Orange Labs, 38-40 rue du Général Leclerc, 92794 Issy-les-Moulineaux, France

Abstract Pricing has been recently regarded as a means to control congestion in communication networks and, therefore, satisfy quality-of-service (QoS) requirements. In a network without connection access control, though, available proposals are generally based on average values, and QoS requirements can be unsatisfied for a part of the traffic.We propose here a simple pricing model for which, if delay exceeds a predefined threshold, a compensation is provided. We study this model by investigating first the level of (elastic) demand for fixed parameters, made of price, threshold, and compensation values, and then find the values maximizing the corresponding revenue. We also compare the results with those when no compensation is provided.

Keywords Pricing · Congestion control · Optimization

How to price Internet access for disloyal users under uncertainty

Tuan Anh Trinh · László Gyarmati

High Speed Networks Laboratory, Department of Telecommunication and Media Informatics, Budapest University of Technology and Economics, 2 Magyar tudósok körútja, Budapest, 1117, Hungary

Abstract It has recently (Trinh 2008; Biczók et al. 2008) been demonstrated that customer loyalty can have a significant impact on Internet service provider (ISP) pricing. However, the results in those works are valid only under the assumption of complete information, i.e., both the ISPs and the customers fully know about each others’ decisions; the question of how Internet access prices are set by the ISP for disloyal users in uncertain circumstances is still largely unsolved. In this paper, we provide a game-theoretic framework to understand the impacts of customer loyalty on ISP price setting under uncertainty. The contribution of the paper is threefold. Firstly, we provide an empirical analysis of the customer loyalty issue by carrying out a survey for theHungarian ISP market and combine the results with other European ISP markets. Secondly, we model ISPs’ uncertain decisions by using Bayesian games. Based on our game theoretic model, we quantify the effects of uncertainty on ISPs’ price setting and derive strategies to optimize ISPs’ profits under these uncertain conditions. After that, we generalize the results to mixed strategy scenarios. Finally, we develop a simulation tool to validate the theoretical results and to demonstrate our novel loyalty models. We argue that our findings can motivate researchers to incorporate a finer-grained user behavior model involving customer loyalty in their investigations of such interactions.

Keywords Socio-economic issues · Cost and pricing · User behavior · Internet access pricing · Game theoretic analysis · Uncertainty management

From charging for Quality of Service to charging for Quality of Experience

Peter Reichl

Telecommunications Research Center Vienna (ftw.), Donaucitystr. 1, 1220 Vienna, Austria

Abstract Providing Quality of Service (QoS) differentiation in future IP-based networks is closely linked to the concurrent implementation of appropriate pricing and charging mechanisms. Thus, in recent years, a broad range of QoS-based charging mechanisms have been proposed, ranging from Paris Metro Pricing and effective bandwidth pricing to the Cumulus Pricing Scheme or the Contract and Balancing Mechanism. However, the strongly increasing interest in Quality of Experience (QoE/QoX) so far has not led to a comparable burst of research activity in the Internet Economics community. Therefore, in order to highlight this important paradigm shift from a charging perspective, we first will review the most prominent QoS-based charging schemes and provide some discussion on lessons learned. In the next step, we describe the imminent transition from QoS to QoX from an economic point of view and discuss recent proposals for pricing of QoX. The paper ends with an outlook on current and future work in this highly interesting research field.

Keywords Telecommunication economics . Quality of Service . Quality of Experience . Charging . Next Generation Networks

A real options model for the transferability value of telecommunications licenses

Loretta Mastroeni¹ · Maurizio Naldi²

¹ Dipartimento di Economia, Universit`a di Roma “Roma Tre”, Via Silvio D’ Amico 77, 00145 Rome, Italy
<sup>2</sup> Dipartimento di Informatica, Sistemi e Produzione, Universit`a di Roma “Tor Vergata”, Via del Politecnico 1, 00133 Rome, Italy

Abstract Licenses for telecommunications services are awarded with a number of side obligations and commitments for the licensee. Under such obligations the licensee is typically not allowed to transfer its license to another operator. Such prohibition may cause heavy inconveniences for customers, so that its removal is strongly advocated and already a reality in many cases. Its removal adds value to the original license and may then constitute a valuable option (the transferability option). A method is here proposed to assess such value, by using the framework of real options. The method is applied in a variety of settings and shows that the value of the option depends superlinearly on the reselling price and the market volatility, and linearly or sub-linearly on the expiry time of the option.

Keywords Licensing · Regulation · Auctions · Telecommunications economics

Open Topics

Extension of the FDTD Huygens subgridding to frequency dependent media

Fumie Costen¹ · Jean-Pierre Bérenger²

¹ School of Electrical and Electronic Engineering, The University of Manchester, Sackville Street Building, Manchester, M60 1QD, UK
²Centre d’Analyse de Défense, 16 bis, Avenue Prieur de la Côte d’Or, 94114, Arcueil, Franc

Abstract A wide range of wireless system developments require knowledge of the distribution of electromagnetic fields from various sources in humans. As experimental assessment is ethically unacceptable, high-resolution numerical dosimetry is needed. The finite-difference time-domain method is the most appropriate due to its simplicity and versatility. Reduction in demands on computational resources can be achieved using subgridding techniques. This paper rigorously introduces frequency dependency to one of the most promising subgridding techniques, Huygens subgridding. The validity of the Huygens surface in lossy media, as well as on the physical interface, is intensively studied.

Keywords Huygens surface · Subgrid · Finite-difference time-domain · Debye media · UWB · Numerical method · Numerical dosimetry

Equation-based end-to-end single-rate multicast congestion control

Wafa Kammoun & Habib Youssef

Research Unit PRINCE, ISITCom H-Sousse, University of Sousse, Sousse, Tunisia

Abstract Among the recently proposed single-rate multicast congestion control protocols is transmission control protocol-friendly multicast congestion control (TFMCC; Widmer and Handley 2001; Floyd et al. 2000; Widmer et al. IEEE Netw 15:28–37, 2001), which is an equation-based single-rate protocol that extends the mechanisms of the unicast TCP-friendly rate control (TFRC) protocol into the multicast domain. In TFMCC, each receiver estimates its throughput using an equation that estimates the steady-state throughput of a TCP source. The source then adjusts its sending rate according to the slowest receiver within the session (a.k.a., current-limiting receiver, CLR). TFMCC is a relatively simple, scalable, and TCP-friendly multicast congestion control protocol. However, TFMCC is hindering its throughput performance by adopting an equation derived from the unicast TFRC protocol. Further, TFMCC is slow to react to congestion conditions that usually result in a change of the CLR. This paper is motivated by these two observations and proposes an improved version of TFMCC, which we refer to as hybrid-TFMCC (or H-TFMCC for short). First, each receiver estimates its throughput using an equation that models the steady-state throughput of a multicast source controlled according to the additive increase multiplicative decrease (AIMD) approach. The second modification consists of adopting a hybrid sender/receiver-based rate control strategy, where the sending rate can be adjusted by the source or initiated by the current or a new CLR. The source monitors RTT variations on the CLR path, in order to rapidly adjust the sending rate to network conditions. Simulation results show that these modifications result in remarkable performance improvement with respect to throughput, time to react, and magnitude of oscillations. We also show that HTFMCC remains TCP-friendly and achieves a higher fairness index than that achieved by TFMCC.

Keywords Multicast transport protocols . Equation-based . Single-rate multicast congestion control . AIMD