Abstract: System for providing alert-based communication services for which corresponding alert conditions to be met by mobile stations are defined. The system includes an alert engine capable of firing alerts associated with the alert-based communication services if location data regarding the mobile stations is indicative of the mobile stations meeting the alert conditions corresponding to the alert-based communication services. A requirements engine is provided for determining an expected earliest future time at which at least one alert condition is capable of being met by a particular mobile station and outputting a data element indicative of a requirement to obtain updated location data about the particular mobile station in advance of the expected earliest future time.

Abstract: A data processing device for use in a communications network capable of supporting users of mobile stations, as well as a method of processing data elements exchanged between a pair of entities in such a network. The invention relies on techniques for receiving and processing the content of data elements that are exchanged or generated in the course of ordinary network operation in order to derive information that can be used to ascertain the location of mobile stations in the network. The location information is provided to a location-based services (LBS) application. Thus, mobile station location information is obtained without the LBS application specifically requesting that such information be generated or exchanged, which potentially relieves the network of a considerable amount of congestion and resource scarcity.

Abstract: In one aspect, a method and system are provided for preprocessing a weighted planar undirected graph and representing the results of the preprocessing so as to facilitate subsequent approximate distance queries. A representation can be constructed so that an approximate distance from one node to another can be computed quickly. Also, the representation in one embodiment stores information for computing distances in a relatively compact format, thus reducing memory requirements. In another aspect, a method and system are provided which use the representation for rapid computation of distances.