Social amplification factor for mobile crowd sensing: the participAct experience

Mobile Crowd Sensing (MCS) aims to coordinate and activate the participation of volunteers willing to use their smartphones to harvest large quantities of data as they move in urban areas. One of the most important requirements in MCS is maximizing the effectiveness of the data gathering campaign. In fact, also due to the initial low penetration rate of MCS apps and to avoid making the MCS process cumbersome to users, only a small portion of the whole citizenship can be involved in such campaign, while most citizens are not part of the process. This paper proposes a novel approach that combines participatory and opportunistic techniques to amplify the amount of data harvested from the crowd. The core idea is that people with similar interests, such as employees of the same company, students or friends tend to meet more frequently with respect to people with different interests. Accordingly, it is possible to opportunistically involve in the crowd sensing loop people in the volunteers' neighborhood. Following that main design guideline, our work assesses the SOcial amplification FActor (SOFA) that allows to increase the number of samples retrievable during a crowd sensing campaign. We show the benefits of SOFA by using the ParticipAct MCS platform and we analyze three different application scenarios. Highly realistic simulation results, based on ParticipAct mobility traces, show the advantages of SOFA, with an amplification factor at the end of the observation time that ranges from 2.5 to 5.