KLPPS: A k-Anonymous Location Privacy Protection Scheme via Dummies and Stackelberg Game

Table 1

Summary of notations.

Symbol	Meaning
	The semantic distance between two locations
	The physical distance between two locations
	The query probability distance between two locations , which is obtained by calculating the difference between the query probabilities of two locations
	Representation of the semantic diversity between locations
	Location access profile of the user (probability of being at location when accessing the LBS)
	Actual location of the user
	Offset location output by the
	Set of possible dummy locations output by the LPPM
	The location privacy protection mechanism (LPPM): probability of replacing with
	Adversary’s estimate of the user’s actual location
	Adversary’s attack function: probability of estimating as user’s actual location, if is observed
	Function of generating offset location: probability of replacing with
	Expected quality loss of an LPPM with location obfuscation function
	Maximum tolerable service quality loss
	Expected location privacy of the user with profile using LPPM against attack