TO Ba Lam

PhD graduated
Team : Phare
Departure date : 09/30/2012

Supervision : Guy PUJOLLE

Co-supervision : NGUYEN Thi-Mai-Trang

Contrôle de Puissance et Routage dans les Réseaux Ad-hoc à Radio Cognitive

A large number of wireless services have been introduced over the last decade to satisfy new demands of mobile users. However, the proliferation of wireless computing and communication devices make the radio spectrum overcrowded. According to many studies of the Federal Communication Commission (FCC), it is revealed in the FCC report that many spectrum bands are used only in bounded geographical areas or over limited periods of time, and that the spectrum utilization varies from 15% to 85%. As a consequence, the Cognitive Radio Networks (CRNs) have been introduced as a new alternative wireless communication paradigm to utilize the radio spectrum more efficiently. In cognitive radio networks, cognitive radio (CR) users opportunistically select the channels for transmission and assure that their transmissions do not affect to the operation of primary users who have an exclusive right to a certain spectrum band. As a result, beside the already known issues of wireless environment, there exist additional issues in CRNs. First, the operation of primary user must not be violated. Second, the diversity in the number of channels that each CR user can use for transmission might limit the node's accessibility to its neighbors. Third, route is unstable due to the frequent arrival and leaving of primary users. In this dissertation, we take these issues into accounts and investigate the power control and routing perspectives to enhance the network performance and power utilization in cognitive radio ad-hoc network. First, aiming to enhance the network performance by deploying a proper network topology for a particular communication purpose, we propose a topology deployment oriented power control scheme for cognitive radio ad-hoc network. The main objectives are: (i) to ensure primary radio operators that none of their users will be penalized by the spectrum reuse; and (ii) to control the transmission power of CR users in which a corresponding network topology will be deployed. Second, to tackle the problem of the frequent arrival and leaving of primary users which can lead to the heavy traffic overhead caused by re-routing, we propose a new approach for joint flow maintenance and power control, called flow-based power control, for cognitive radio ad-hoc network. By maximizing the number of concurrent flows under new arrivals of primary users, the power control scheme targets on: (i) reducing the re-routing, and (ii) to utilize the power resource more efficiently by only allocating power resource to the maintained flows. Finally, we propose an application-oriented routing protocol (AORP) in cognitive radio ad-hoc network. We observed that each application has its own transmission behaviour and different kinds of channel pattern will be appropriate for different applications to use for transmitting data. Hence, to enhance the network performance by reducing the channel competition, AORP builds the route for data transmission in combination with channel selection based on the application of the node initializing the data transmission.

Defence : 07/19/2012 - Site Jussieu - Salle Jean-Louis Laurière - 25-26/101

Jury members :

Khaldoun Al Agha, Professeur à l'Université Paris-Sud [Rapporteur]
Yacine Ghamri-Doudane, HDR à Ecole Nationale Supérieure d'Informatique pour l'Industrie et l'Entreprise [Rapporteur]
Marcelo Dias de Amorim, Directeur de recherche CNRS/UPMC
Pedro Braconnot Velloso, Maitre de conférences à Universidade Federal Fluminense, Brésil
Guy Pujolle, Professeur à UPMC Sorbonne Universités
Thi Mai Trang Nguyen, HDR à UPMC Sorbonne Universités

2010-2012 Publications