AGGREGATED TRAFFIC GENERATION IN FTTX NETWORKS R.García, V. García, X.G. Pañeda, D. Melendi, A. Neira Computer Science Department, University of Oviedo Campus Universitario de Viesques. Sede Departamental Oeste 33204 Xixón-Gijón Asturias, Spain Telephone: 985182488 – Fax: 985 18 19 86 {roberto,victor,xabiel,melendi,neira}@correo.uniovi.es ABSTRACT The aim of this paper is to model the traffic generated in a FTTX network for voice and data transmission. Thus, we commence with a traffic model that represents the use that network subscribers make of the system, allowing the generation of requests sent by the subscribers connected to the return channels. The model uses the number of subscribers assigned to each return channel. The traffic in each return channel is obtained from the aggregation of the separated traffic streams originated by the user’s applications executed. Later, a model of the branches from the cable network is developed, considering both the upstream channels and the downstream channel of the controller. The results obtained in these processes can be validated using the real data provided by a FTTX cable operator. For the accomplishment of the model, the OPNET simulation language has been used. In addition, the results have been exported to MATLAB, which permits the execution of all types of statistical analyses, with the aim of both making the verification of the results and the validation of the developed model. KEYWORDS Traffic, aggregate, fiber network, model, applications, validation. 1. INTRODUCTION The great growth experienced in the last years by information technologies, mainly due to the expansion of the Internet, has also meant a considerable increase in the volume of traffic and number of users and in types of applications. This fact has motivated the study of the statistical characteristics of the traffic generated in the network, which is determined by the users behaviour and the actions of the necessary protocols for the communications between the different elements in the networks [6,7,5]. To have access to wider bandwidths with low costs, a network access technology is needed in order to connect broadband transmission lines, over optical fiber, with the end users, guaranteeing QoS for all the applications [10]. Historically, the telecommunication providers have used hybrid distribution systems of fiber and coaxial technologies (HFC, Hybrid Coaxial Fiber), where the optical fiber is used in the backbone of the network and the coaxial cable connects the backbone with the individual users. More recently, the telecommunication operators have begun to replace portions of coaxial cable with optical fiber to obtain the advantages of a greater quality, flexibility and efficiency of the technology based on the optical fiber and its associated optical devices. These circumstances have led to the appearance of FTTX technologies, where the optical fiber directly takes broadband services to the home (FTTH: Fiber To The Home), to the curb (FTTC: Fiber To The Curb) or to a building (FTTB: Fiber To The Building). Rigorous studies made of high quality samples from data networks, have demonstrated that traffic processes present the statistical property of self-similarity, which cannot be obtained from the traditional models of Poisson [9,13,3]. The characteristic of these self-similar processes is that they present a long- range-dependence (LRD), defined as a slow decrement in the autocorrelation function, of the form: ∞ → ∝ − − k k c k r H r , ) ( ) 2 2 (