Fluid modeling for K-tier cellular networks

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Ajouté le: 27/05/2014
Directeur : ZITOUNE Lynda - Lynda.ZITOUNE@lss.supelec.fr
Titre : Fluid modeling for K-tier cellular networks
Thèmes : Automatique, Signal, Télécoms, Systèmes embarqués
Laboratoires : L2S Laboratoire des Signaux et Systèmes UMR 8506
Description :

Keywords: Heterogeneous networks, interference management, cell association and biasing, energy saving, fluid modeling

 Thesis context

    Small cell and more generally femtocell technologies are used to face the rapid growth of cellular network traffic in terms of density and diversity. A small cell or a femtocell is a low-cost low power base station, used in a plug and play manner by customers.  Originally, femtocells envisioned as a way to provide better coverage for voice data in case of indoor utilization, are nowadays, used to offload macro-cellular networks and to improve both capacity and coverage in both indoor and outdoor utilization.

     Deployment of femtocells within a macro cellular network forms an heterogeneous network also called 2-tier network. More generally, an heterogeneous network (k-tier network) is an economical and efficient solution to increase capacity and coverage in radio transmission. However, communications suffer from interferences due the spectrum sharing and the random location of femtocell base stations. Several solutions have been proposed for spectrum management and resource sharing including power control, multiple antennas, adaptive FAP (Femtocell Access Point), cognitive radio. Other issues are still open related to handover, security, authentication and energy consumption. The topic addressed in this thesis deals with the problem of energy saving and cell association in an heterogeneous network. The work at developing a tractable and an accurate model to represent the behavior of heterogeneous network using spatial fluid modeling.

 

 Thesis expectation

    Stochastic geometry modeling tools are extensively used to develop more tractable analytical models to study the performance of k-tier networks in terms of the probability of coverage/outage and throughput. For example, Poisson Point Process is used to describe the position of the femtocell base stations and the mobile users and to derive the communication performance like the coverage/outage probability and the throughput. However, stochastic models are difficult to compute, and in most cases simulation is used to evaluate their accuracy. 

     To reduce the computation complexity, a fluid modeling is used without over-simplifying the model.  The spatial fluid modeling was used in macro cellular network to give an explicit expression of the interference factor and to take into account the distance a mobile to its serving base station. The model of the interference factor obtained like so, was used to evaluate the network performance like :  the capacity, the outage probability and the quality of service over macro cellular network.

    The objective of this thesis research is to use spatial fluid modeling to evaluate the performance of a k-tier network using directional/beamforming antennas. This work will consist in two parts. The first part focus on the extension of the fluid model of the interference factor to consider the constraints of directional/beamforming antennas on both the uplink and the downlink. The derived model allows then to evaluate the capacity, the coverage and the outage probability.  In the second part, the work will be focused on the network connectivity in case  of outdoor deployment of femtocells. The obtained model will serve to study the impact of the association and biasing policies, to define some energy saving policies and to evaluate the gain on the network with respect to coverage and capacity.  

 

Brief description of scientific and technical steps — this thesis aims to study and propose innovative models for the multicellular networks. The PhD involves the steps sketched below. 

Bibliography on k-tier cellular networks 

Bibliography on Point Process  and fluid models

Study of alternative models

  • Study of energy saving policies and modeling

 

 Pre-requisites — The applicant, beyond the Master degree (acquired in telecommunication engineering or computer science, for example), should have good skills in networks protocols, 3G and 4G cellular mobile networks, simulation, probability and performance evaluation, stochastic modeling and C/C++ programming.

 

Skills fostered/gained during PhD — The PhD is at the crossroad of two scientific areas: modeling and cellular networking.

 

[1] J. G. Andrews, H. Claussen, M. Dohler, S. Rangan, and M. C. Reed, “Femtocells: Past, present, and future,” IEEE Journal on Selected Areas in Communications, vol. 30, no. 3, pp. 497–508, 2012.

 [2] W. C. Cheung, T. Quek, and M. Kountouris, “Throughput optimization, spectrum allocation, and access control in two-tier femtocell networks,” IEEE Journal on Selected Areas in Communications, vol. 30, no. 3, pp. 561–574, 2012.

 

[3] J.M. Kelif, M. Coupechoux and P. Godlewski, “A Fluid Model for Performance Analysis in Cellular Networks”, EURASIP Journal on Wireless Communications and Networking - Special issue on interference management in wireless communication systems: theory and applications Volume 2010, January 2010

 

[4]  H. Wang, X. Zhou, and M. C. Reed, “Analytical evaluation of coverage oriented femtocell network deployment,” CoRR, vol. abs/1305.3356, 2013.

 

 

Supervisors

  • Lynda Zitoune, Assistant Professor

email: Lynda.ZITOUNE@lss.supelec.fr, phone: +33 1 69 85 17 64

 

  • Véronique Vèque, Professor

email: Veronique.VEQUE@lss.supelec.fr, phone: +33 1 69 85 17 22