Energy Efficiency and Privacy in Device-to-Device Communication

Mobile data traffic has increased many folds in recent years and current cellular networks are undeniably overloaded to meet the escalating user's demands of higher bandwidth and data rates. To meet such demands, Device-to-Device (D2D) communication is regarded as a potential solution to solve the capacity bottleneck problem in legacy cellular networks. Apart from offloading cellular traffic, D2D communication, due to its intrinsic property to rely on proximity, enables a broad range of proximity-based applications for both public safety and commercial users. Some potential applications, among others, include, proximity-based social interactions, exchange of information, advertisements and Vehicle-to-Vehicle (V2V) communication. The success of D2D communication depends upon the scenarios in which the users in the proximity interact with each other. Although there is a lot of work on resource allocation and interference management in D2D networks, very few works focus on the architectural aspects of D2D communication, emphasizing the benchmarking of energy efficiency for different application scenarios. In this dissertation, we benchmark the energy consumption of D2D User Equipments (UEs) in different application scenarios. To this end, first we consider a scenario wherein different UEs, interested in sharing the same service, form a Mobile Cloud (MC). Since, some UEs can involve in multiple services/applications at a time, there is a possibility of interacting with multiple MCs. In this regard, we find that there is a threshold for the number of UEs in each MC, who can participate in multiple applications, beyond which legacy cellular communication starts performing better in terms of overall energy consumption of all UEs in the system. Thereafter, we extend the concept of MC to build a multi-hop D2D network and evaluate the energy consumption of UEs for a content distribution application across the network. In this work, we optimize the size of an MC to get the maximum energy savings. Apart from many advantages, D2D communication poses potential challenges in terms of security and privacy. As a solution, we propose to bootstrap trust in D2D UEs before establishing any connection with unknown users. In particular, we propose Pretty Good Privacy (PGP) and reputation based mechanisms in D2D networks. Finally, to preserve user's privacy and to secure the contents, we propose to encrypt the contents cached at D2D nodes (or any other caching server). In particular, we leverage convergent encryption that can provide an extra benefit of eliminating duplicate contents from the caching server.