Participants
Participatory participants - assuming the active involvement of participants in choosing to contribute data
Opportunistic participants - refer to autonomous data collection, not requiring explicit user interaction
Example
For example, an MCS traffic monitoring application involves numerous individuals who continuously contribute location data to cloud servers which estimate traffic conditions by processing a large number of location readings in real-time. The users can opt to continuously provide their location data in exchange of the ability to track traffic conditions on their mobile devices. Traffic statistics can be used by city officials to detect highly-congested roads and traffic hotspots, or to correlate this data, e.g., with air quality. The sensed location data is typically provided to cloud servers autonomously and periodically, and can be classified as opportunistic sensing: