Patent ID: 7991382
Filing Date: 2011-08-02
Classification: H04L,H04W

Abstract:
1. A method of conveying location of a cellular wireless communication device (WCD) to an emergency service system comprising a Public Safety Answering Point (PSAP), the WCD including a GPS receiver, a compass, a pedometer, and a wireless transceiver, the method comprising: the WCD applying the GPS receiver to receive GPS satellite signals, and the WCD using the received signals to determine GPS location coordinates of the WCD; the WCD thereafter entering a building and detecting that the WCD is unable to receive GPS satellite signals, and, responsive to being unable to receive GPS satellite signals, the WCD then using the compass and pedometer to establish at least one direction of travel of the WCD and at least one distance of travel of the WCD; while in the building, the WCD receiving a user request to initiate an emergency service call, and the WCD responsively using the wireless transceiver to transmit via an air interface and radio access network serving the WCD, into a packet-switched network, a Session Initiation Protocol (SIP) INVITE message carrying (a) the GPS location coordinates and (b) indications of the at least one determined direction of travel of the WCD and the at least one determined distance of travel of the WCD; a network server (i) receiving the transmitted SIP INVITE message, (ii) reading the GPS location coordinates and indications of at least one determined direction of travel and at least one determined distance of travel from the SIP INVITE message, (iii) using the at least one determined direction of travel and at least one determined distance of travel to update the GPS location coordinates so as to establish indoor location coordinates, (iv) referencing mapping data to translate the indoor location coordinates into a building portion descriptor that describes a portion of a building where the indoor location coordinates reside in the building, and (v) transmitting the SIP INVITE message, including the building portion descriptor, along to the emergency service system, wherein the SIP INVITE message invokes establishment of a Real-time Transport Protocol (RTP) session between the PSAP and the WCD, whereby building portion descriptor is presented to a human PSAP operator and thereby facilitates emergency response.