ABSTRACT
Location-based service (LBS) is a generic name for new kinds of services, where location information is an important parameter. There is no common defi nition for LBSs. Other terms mean the same as LBS and are used interchangeably (Kupper 2005), like location-aware service, location-related service, or location service. LBSs are intended to be the killer application in the next few years. Nowadays, the rapid development in the areas of mobile computing and advanced techniques enables location-aware mobile services to be developed. Those services may be value-added services or a completely new service. Location information is not usually relevant data to provide a useful service, and it must be combined with other content data to provide an attractive application to users. For example, location information can be used as (GSM 2003):
• A fi lter: when users request the search of a service, only results that are close to the user location are returned to users.
