Range- k NN queries with privacy protection in a mobile environment

With the help of location-based services (LBS), mobile users are able to access their actual locations, which can be used to search for information around them which they are interested in. One typical thing is that mobile users are more likely to protect their personal information such as their actual locations. In order to protect the privacy of users' personal information, we proposed Range- k NN queries, which uses the query range instead of one single query point. A Landmark Tree (LT), which indexes all the location information, is used to hide the actual user location in a specific radius. Through this LT, the query range, which covers the actual user location, is sent to the server for processing instead of the actual user location. In the evaluation part, our algorithm is proved to be more precise than range queries, and the overall search performance is quite efficient.