Doctorate thesis defense of Jihene BEN ABDERRAZAK BCHIR

Committee

Abstract

Driven by the proliferation of advanced user terminals and bandwidth greedy applications, data traffic in wireless networks has been increasing exponentially in the recent years. However, a massive data traffic demand may lead to an aggressive reuse of the frequency resources which generates inter-cell interference and downgrades the network performance. Future wireless systems are then expected to leverage a number of emerging technologies to meet the ever-increasing need for capacity and coverage. Interference management has been a key enabler for the deployment of future wireless systems requiring a dense spectrum reuse. Moreover, densely deployed small and low-cost base stations are embedded into the conventional cellular network topology to form a so-called heterogeneous network. Although it is an effective way to improve the spatial reuse and to increase the network capacity, the dense co-channel deployment of small cells may yield to insufficient traffic offoading and to severe interference problems. Therefore, different interference mitigation techniques have been put forward in order to boost the system capacity and the spectrum efficiency. In this thesis, we studied different inter-cell interference coordination techniques and proposed new ones based on the coordination between the neighboring cells for the case of homogeneous networks with a full frequency reuse. We proposed tailored fractional frequency reuse schemes for both homogeneous and heterogeneous networks. Besides, we focused on the time-domain technique suited for heterogeneous networks where the macro base stations are muted during some subframes, called almost blank subframes, in order to reduce the interference on the offloaded users. In this context, we studied the problem of joint load balancing and interference mitigation. We proposed new user association schemes that improve the users' satisfaction while considering the load of the different cells as well as the users' Quality of Service requirements. Finally, in this time of heightening environmental concerns, we also tackled the joint optimization of the user association and the power consumption while overcoming the interference issues.

Keywords

: future networks, inter-cell interference, coordination, frequency reuse, almost blank subframes, heterogeneous networks, optimization, user association, load balancing, power minimization.