Energy-efficient content distribution via mobile users cooperations in cellular networks

Exploiting cooperation of mobile stations (MSs) for content distribution has been considered as a promising approach to offload the rapidly growing traffic demand in cellular networks. This paper proposes a framework of MSs’ energy-efficient cooperation for distributing realtime content blocks (CBs). Given a group of MSs interested in downloading a set of CBs from the cellular base station (BS), we propose a cooperative scheme in which, the BS first unicasts the CBs to some selected MSs, who then relay their received data to other MSs such that all MSs can receive their required CBs. Regarding this cooperative scheme, we aim at jointly optimizing each CB’s transmission rate and each MS’s relay-strategy (namely, relaying which subset of CBs and for how long), such that the total energy consumption of the BS and all MSs can be minimized. Such an optimization problem is challenging to solve, since the CBs’ transmission rates significantly influence the MSs’ relay-strategies. To tackle this difficulty, we explore the layered structure of the formulated optimization problem and propose a corresponding layered algorithm (including a top-layer algorithm and a bottom-layer algorithm) to compute the optimal solution. Numerical results are provided to validate our proposed algorithm and show the performance advantages of our proposed scheme for the MSs’ cooperative content distribution.