Energy-Optimal Scheduling of Mobile Cloud Computing Based on a Modified Lyapunov Optimization Method

Application offloading is an effective method for extending the battery life of mobile devices by executing some tasks of a mobile application in the cloud. This paper provides an energy-optimal transmission rate scheduling scheme executed at mobile devices in application offloading process. Our objective is to conserve energy for the mobile devices by optimally adjusting the transmission rate of mobile applications. Instead of adopting the widely used dynamic programming (DP) algorithm, we propose a modified Lyapunov optimization method. The method is obtained by modifying the Lyapunov optimization method to adapt it for mobile cloud computing scenario. Compared to DP algorithm which is in need of the statistical information of the stochastic wireless channels, the most important advantage of our proposed method is that it can obtain a closed-form expression for transmission rate only according to the actual measurement of the channel gain in each time slot and thereby can avoid the deviation from prediction of the channel gain in future time slots. The numerical results demonstrate that our proposed method can save about 30% of the energy compared to DP algorithm.