Energy-aware cooperative content distribution with dynamic topologies -

Abstract

Multimedia services such as video streaming and online games have been widely spread with the rapid evolution of wireless communication technologies that provide high data rates. The prolonged usage of such services requires the wireless interfaces to be active for long periods, thus increasing the energy consumption which raises a challenge for the designers of battery-operated mobile terminals (MTs). Optimized cooperative content distribution approaches with device-to-device (D2D) cooperation, have been proposed in the literature to reduce the high energy consumption. However, most of these approaches do not take into consideration the variations in the network (MTs leaving, new MTs joining, and-or MTs moving around). This thesis is divided into two main parts. In the first part, we present pseudo-optimal energy-efficient cooperative content distribution algorithms that account for different types of mobility in the network. The content distribution problem is first formulated using two static optimization problems: minimum spanning tree (MST) formulation and two-hop integer programming optimization formulation. Both formulations return optimal solutions at a given point in time. However, upon any variation in the network, the content distribution solution needs to be updated. Since re-solving the optimization problems is computationally expensive, a re-optimization algorithm that returns sub-optimal solutions is proposed for each type of mobility (node insertion, node deletion, edge weight modification). Simulation results for various scenarios demonstrate performance close to the optimal, with major reduction in computational complexity. In the second part of the thesis, we discuss dynamic cooperative content distribution architectures with the following components: network formation, detection and selection mechanisms, and failure detection and recovery mechanisms.