Abstract: In fast growing world, the best method for a person to know his/her location with the help of devices having GPS facility. When mobile userís location is available to LBS, it is very easy to user to know all location dependent information like location of friends or Nearest Restaurant, whether or traffic conditions. The massive use of mobile devices its open the way for the creation of wireless networks that can be used to exchange information based on locations. This type of service is known as location based service .When the exchange of location information is done amongst entrusted parties, the privacy of the user could be in harmful. Existing protocol doesnít work on many different mobile devices and another issue is that, Location Server (LS) should provide misleading data to user. So we are working on enhancement of this protocol.

Keywords: Location Privacy, Private Information Retrieval, Centroid.