Speeding up Smartphone-Based Dew Computing: In Vivo Experiments Setup Via an Evolutionary Algorithm.

Dew computing aims to minimize the dependency on remote clouds by exploiting nearby nodes for solving non-trivial computational tasks, e.g., AI inferences. Nowadays, smartphones are good candidates for computing nodes; hence, smartphone clusters have been proposed to accomplish this task and load balancing is frequently a subject of research. Using the same real-i.e., in vivo-testbeds to evaluate different load balancing strategies based on energy utilization is challenging and time consuming. In principle, test repetition requires a platform to control battery charging periods between repetitions. Our Motrol hard-soft device has such a capability; however, it lacks a mechanism to assure and reduce the time in which all smartphone batteries reach the level required by the next test. We propose an evolutionary algorithm to execute smartphone battery (dis)charging plans to minimize test preparation time. Charging plans proposed by the algorithm include charging at different speeds, which is achieved by charging at maximum speed while exercising energy hungry components (the CPU and screen). To evaluate the algorithm, we use various charging/discharging battery traces of real smartphones and we compare the time-taken for our method to collectively prepare a set of smartphones versus that of individually (dis)charging all smartphones at maximum speed.

Motrol: A hardware-software device for batch benchmarking and profiling of in-lab mobile device clusters.

Motrol is a simple device that satisfies functional requirements necessary for the automatic execution of battery-driven tests and profiling of connected mobile devices. It is specifically a hardware/software platform that allows Dew Computing researchers and developers to automate performance tests on Android-based smartphones. The hardware is based on a NodeMCU Esp8266 microcontroller that runs a firmware for managing the outputs. This software allows enabling/disabling the relays that connect the sockets that power the chargers of up to 4 mobile devices minimizing the need for human intervention. The firmware runs a web server that serves Rest requests from a Rest client with the commands to drive the digital outputs. These digital outputs activate or deactivate the relays to allow current to pass or not to the sockets. Such capability is essential to automate the study of battery behavior on battery-driven devices such as smartphones. Motrol is easy to assemble, knowledge in electronics or programming languages is not necessary, it is constructed with open hardware, and it is cheap, being its total cost ∼USD 30.