Improving Smartphone Battery Life Utilizing Device-to-device Cooperative   Relays Underlaying LTE Networks
  The utility of smartphones has been limited to a great extent by their short battery life. In this work, we propose a new approach to prolonging smartphone battery life. We introduce the notions of "valueless" and "valued battery", as being the available battery when the user does or does not have access to a power source, respectively. We propose a cooperative system where users with high battery level help carry the traffic of users with low battery level. Our scheme helps increase the amount of valued battery in the network, thus it reduces the chance of users running out of battery early. Our system can be realized in the form of a proximity service (ProSe) which utilizes a device-to-device (D2D) communication architecture underlaying LTE. We show through simulations that our system reduces the probability of cellular users running out of battery before their target usage time (probability of outage). Our simulator source code is made available to the public. 
Tuan Ta, John S. Baras, Chenxi Zhu
cs.NI