The sensing systems that monitor physical environments rely on communication infrastructures (wired or wireless) to collect data from the sensors embedded in the environment. However, in many urban environments pre-existing communication infrastructures are not available, and installing new infrastructures is unjustifiably expensive and/or technically infeasible. For such environments, we envision
Participatory Data Transfer
) as an alternative communication medium that leverages users participation for data transfer. With PDT, users use mobile devices to receive data from sensors, and forward the sensed data through the ad hoc network of the mobile devices until the data is received by the data aggregators (i.e., data sinks). Sensor deployment and ad hoc routing/networking are two related problems that are both extensively studied in the literature. However, to enable efficient deployment of PDT for sensing applications one needs to consider the requirements of the two aforementioned problems in conjunction. In this paper, we present a case study of PDT with which we explore the performance of PDT-based data transfer with a sample urban sensing application, namely, an urban temperature monitoring application. Our experimental case study is by simulation based on real datasets including GPS track data for more than 2000 vehicles in the city of Beijing. We discuss our observations based on this case study which can serve as directions to design application-specific optimal PDT mechanisms.