National Natural Science Foundation of China (61370077, 61003057)
Privacy protection problem in location based service receives continuous attentions in recent years, especially for location privacy protection in location based nearest neighbors query. Existing work however often neglects or fails to cultivate in accommodating query users' privacy preference requirements. The constraint of privacy preference burdens the trade-off between location privacy protection and quality of service in privacy-aware location based query service. Several issues need to be addressed:(1) Privacy preferences contradict with privacy models diametrically in terms of personality and commonality they focus on; (2) There is a dilemma between privacy preferences and query performance that preferences require intermediate query results be dynamic and adjustable while simplified intermediate query results commonly promise good performances; and (3) Privacy preferences incur the attack originated from intersection inferring to candidate answer sets in continuous location based queries. In this survey, the privacy preference problem in location based nearest neighbor query is identified and presented. The performance of existing location obfuscation and query techniques, as well as their ability in accommodating users' privacy preferences, are discussed in terms of location obfuscation principle and inherent restricting mechanism between nearest neighbor query performance and location protection. Subsequently, inherent restricting mechanism between location privacy preserving nearest neighbors query and privacy preference support is detailed, and some major problems originated from location privacy preference are demonstrated. Finally, some possible solutions to these problems are elaborated and the future research work is suggested.