Energy efficient offloading for competing users on a shared communication channel

In this paper we consider mobile users that employ computation offloading. In computational offloading, users can reduce energy consumption by executing jobs on a remote cloud server, rather than locally. In order to execute a job in the cloud, a mobile user must upload the job over a base station channel which is shared by all of the uploading users. The jobs are subject to hard deadline constraints, and since the channel quality may be different for each user, this may restrict the users ability to reduce energy usage. The system is modelled as a competitive game where each user is interested in minimizing its own energy use. The game is subject to the real-time constraints imposed by job execution deadlines, user specific channel bit rates, and the competition over the shared communication channel. The paper shows that for known classes of parameters, a game where each user independently adjusts its offload decisions always has a pure Nash equilibrium, and a Gauss-Seidel-like method for determining this equilibrium is presented. Results are then presented which illustrate that the system always converges to a Nash equilibrium using Gauss-Seidel. Data is presented which show the number of Nash equilibria that are found, the number of iterations required, and the quality of the solutions obtained. In particular, we find that the solutions perform well compared to a lower bound on total energy performance.