A Novel Negative Location Collection Method for Finding Aggregated Locations

Currently, many intelligent transportation systems (ITSs) require aggregation of location information. Although users enjoy the convenience of ITSs, privacy concerns have resulted in user's caution in offering location information. Certain studies have been performed to preserve user location privacy. However, most studies that focus on preserving location privacy require a trusted third party or do not consider the movements of users. In this paper, we propose a method based on negative surveys that can be used to estimate the number of people in geographic locations. This method, which can preserve user privacy regardless of user movements, adopts a simple negative survey algorithm for user devices and an estimation algorithm for the server and might be suitable for low-power mobile devices. The experimental results demonstrate that our method is capable of locating the people's gathering places with fine control granularity, which renders it a promising application.