Abstract: Location privacy disclosure has become main constraint of LBS applications,while most existing location privacyprotection methods do not consider the background of mobile users——the road network．A location privacy protection method over road networks was presented．This method consists of three phases．First,in order to meet the requirement of segment l-diversity,the road-network Voronoi diagram is constructed based on the structure of the road network．Second,VK-privacy model is put forward．It satisfies all the users’ privacy requirement in the cloaking set and effectively insures the QoS of LBS．Finally,a clocking algorithm based on VK-privacy model is presented,which improves processing efficiency and safety by cloaking multiple users in the same V-region together．The method takes full account of the structure characteristics of road networks and leverages users’ privacy requirement and QoS of LBS．The robustness against inference attacksof the method was proved through theoretical analysis,and the feasibility of the method was proved by the experimental data.

Key words: LBS,Location privacy,Road network,Voronoi diagram