Patent ID: 7406318

Claim:
An apparatus for calculating an enhanced observed time difference from a mobile station and transmitting the enhanced observed time difference to a servicing mobile location center for a location-based service, the apparatus comprising: means for receiving a location-measuring request and assistance data from the servicing mobile location center; means for choosing a base transceiver station, the synchronization channel of which is to be measured, based on response time detected from the location-measuring request and a predetermined priority; and means for calculating an enhanced observed time difference for the chosen base transceiver station and transmitting a location-measuring response, including the calculation result, to the servicing mobile location center, wherein said predetermined priority is set to a priority order of: [1] an overlap between a channel list included in the assistance data and a list of a number of nearby cells having a higher priority than [2] a broadcast control channel allocation list excepting the channel list included in the assistance data and the list of nearby cells.