Preserving Anonymity in Indoor Location System by Context Sensing and Camera-Based Tracking

In this paper, we present a novel indoor location system, called Activity based Location Tracking and Identification (ALTI), which uses a combination of a camera-based tracking system in the environment and mobile devices with motion sensors. In the indoor environment, GPS-based location systems cannot offer precise location information as they fail to find the required number of GPS satellites. Therefore, many indoor location systems are proposed and developed. However, these systems still have the following two issues if they are applied for the public spaces, such as a shopping mall, an underground mall and a station where many general public visit: (1) many of location systems manage location information in centralized severs, but many people do not want to have their locations in public spaces managed by others (privacy issue) and (2) many of location systems need dedicated user devices, we can not expect that all the people in the public spaces carrying such devices (special device issue). ALTI is based on the combination of camera-based tracking system which generates anonymous user's location information and mobile phone handsets as the user's devices. ALTI solves the above issues by using mobile phone handsets as the user's devices for the special device issue and by estimating the user's location within his/her mobile phone handset assisted by anonymous location information from camera-based tracking system for the first issue. As a results, the ALTI offers fairly good user privacy. This paper describes the detailed mechanism of ALTI and shows the feasibility of it through a preliminary evaluation using the actual visual tracking system and the prototype terminal devices.