Image Number 4 for United States Patent #8351942.
In a method to support geo-location emergency services in a wireless network, a request message is transmitted from a source base station of one vendor to a target base station of another vendor. For example, the request message might be sent subsequent to a wireless unit initiating an emergency services communication, where it is desired to determine the location of the wireless unit by radiolocation, or otherwise at the network level. Upon receiving the request message, the target base station transmits a report message to the source base station, which includes a one-way transmission delay (or other propagation delay information) of the wireless unit as measured at the target base station. Communication protocols in the network are configured so that there are no automatic transmissions of propagation delay information. Instead, base stations transmit propagation delay information only upon the receipt of request messages requesting the information.