E$PA: Energy, Usage ($), and Performance-Aware LTE-WiFi Adaptive Activation Scheme for Smartphones

We propose E$PA, an adaptive LTE/WiFi network interface activation algorithm with supporting system design and multi-attribute cost function for smartphones file transfer services (e.g., downloading a movie file). E$PA's cost function incorporates battery life (energy), data usage quota ($), and expected file transfer completion time (performance) simultaneously, and is motivated by the growing sensitivity of todays smartphone users to these attributes. Each time the individual attributes are calculated and updated, E$PA selects one of the three modes that minimizes the overall cost: (i) activation of both LTE and WiFi interfaces for parallel data transfer; (ii) LTE interface activation only; or (iii) WiFi interface activation only. The primary benefit of the E$PA is that it enables the smartphone to always operate in the "best" mode without the need for users manual control; the energy saving mode if the remaining battery energy is becoming nearly depleted; the cost-saving mode if the remaining data quota is almost running out; or, the maximum throughput mode if remaining data quota and battery life are both sufficient. Our multi-attribute cost model also takes into account the overheads (delays and energy consumption) associated with network interface turn-on/off and switching, as they impact the estimations of both performance (transfer time) and energy (battery life) attributes. Simulation results show that E$PA indeed chooses the "best" operational mode by maintaining dynamic balance among transfer time, energy consumption, and service charge.