Mobile E-Witness

This paper describes the design, implementation and experimental evaluation of a system prototype, named Mobile E-Witness (MEW), which enables the acquisition and remote storage of multimedia (i.e., audio and video) data streams. In essence, MEW consists of a mobile device, incorporating a camera and a microphone, which can be “worn” (i.e., it can be carried without causing any impediment) by public officers, such as policemen and health care operators, in order to record the events these officers witness while on duty. MEW transmits the audio and video data recordings it takes to a remote storage service which maintains these recordings for future replay. Thus, for example, an event recording can be used as an impartial testimony to resolve disputes concerning the relative responsibilities of those participating to the recorded event, including the officers themselves (hence the name Mobile E-Witness). The infrastructure MEW uses for communications with the remote storage service consists of the wired and wireless communication infrastructures publicly available in metropolitan areas, including the Internet. MEW utilizes these infrastructures in order to (1) ensure that sufficient bandwidth for multimedia data transmission is available, (2) guarantee highly available communications, (3) limit the power consumption for the multimedia transmission and, finally, (4) limit the electromagnetic radiation emanation of the device worn by the public officers. We have carried out an experimental evaluation of a MEW prototype in the city of Bologna. The results of this evaluation, reported in this paper, confirm the potential of our system.