Prolonging battery usage time in smart phones

As smart phones usually have large high-resolution screens, many fancy functions, multiple communication modes and interfaces, and powerful processing capabilities, their power consumption is unsurprisingly much higher than traditional voice-centric phones. Unfortunately, the growth of battery capacity is far below the needs of smart phones and new applications, hence it is of great importance and strong interest to mobile users and service providers to prolong the usage time of smart phones without affecting quality of service (QoS) and user experience. To address this challenging issue, we develop a cross-disciplinary approach in this paper by jointly considering battery discharge and recovery characteristics with service/user requirements in energy efficient protocol design. Specifically, based on extensive experiments, we study and model the characteristics of battery recovery effect in a smart phone, under different discharge currents, discharge time and recovery time. A practical power consumption model for smart phone is then derived from real measurement data and empirical formulae. Further, this new model is applied to develop and implement a battery-aware protocol for online continuous music streaming service. Experimental results show the proposed protocol can effectively exploit the battery recovery effect in a smart phone and achieve a 10% gain in usage time while satisfying standard service and user requirements.