Smartphone-assisted energy efficient data communication for wearable devices

In dynamically changing network environments, no single data communication approaches for wearable devices are guaranteed to yield the best performance-cost ratio. To illustrate how different approaches perform in different environments, we conduct a theoretical analysis to four basic approaches that rely on either Wi-Fi, or smartphone-tethered cellular network, or both, to transmit data on wearable devices. In order to achieve energy efficient data communication on wearable devices (and associated smartphones), we propose a Lyapunov based on-line approach designation mechanism that dynamically chooses an appropriate data communication approach based on data transmission queue, estimated network conditions and the device moving speed. Due to the property of Lyapunov optimization framework, the proposed mechanism is able to minimize the power consumption of data communication for wearable devices (and associated smartphones) while meeting the delay time constraint. Moreover, it requires no prior knowledge of future network conditions and data request arrivals. Our trace-driven simulations demonstrate that our on-line designation mechanism delivers very close performance to the mechanism that can foresee the future, leaving very little space for further improvement.