Location determination for mobile devices in emergency situations

A method of determining location information for a mobile communication device, the method implemented as instructions executed by a processor of the mobile communication device, the method comprising:

• determining that a position-determining subsystem cannot provide location information for an emergency call;
• sending a locator activation request for at least temporary activation of one or more of a plurality of radio transceivers of at least another mobile communication device;
• broadcasting an emergency location request message using a radio transceiver on the mobile communication device wherein the emergency location request message includes a unique identifier of the mobile communication device and a received signal strength indication (RSSI) value to enable the at least another mobile communication device to determine if it should respond to the emergency location request message;
• receiving one or more emergency location response messages from the at least another mobile device in response to the emergency location request message received on the activated radio transceivers, each of the emergency location response messages comprising external location information from the at least another mobile device and information for determining a distance estimate;
• and
• determining location information for the mobile device using the external location information received in the one or more emergency location response messages and the distance estimate.

An emergency locator component stored in memory and executed by a processor of a mobile communication device, the emergency locator component comprising:

• an emergency locator control module operative to:
• broadcast and receive emergency location request messages using a radio transceiver on the mobile device in response to a determination that a position-determining subsystem is unable to provide location information for an emergency call wherein the emergency location request message includes a unique identifier of the mobile communication device and a received signal strength indication (RSSI) value to enable the at least another mobile communication device to determine if it should respond to the emergency location request message;
• and
• send and receive emergency location information response messages comprising location information of mobile devices and information for determining a distance estimate;
• a location determination module operative to determine the location of the mobile device based at least on the location information received in emergency location information response messages and the distance estimate.

A system for determining a location of a mobile communication device, the system comprising:

• a first mobile communication device comprising:
• a radio transceiver for sending and receiving messages;
• a memory coupled to a processor for executing an emergency locator component operative to:
• broadcast an emergency location request message using the radio transceiver on the first mobile device wherein the emergency location request message includes a unique identifier of the mobile communication device and a received signal strength indication (RSSI) value to enable the at least another mobile communication device to determine if it should respond to the emergency location request message;
• receive an emergency location response message comprising location information and information for determining a distance estimate;
• and
• determine location information for the first mobile device based location information received in the emergency location response message and the distance estimate;
• and
• a second mobile communication device comprising:
• a Global Positioning System (GPS) receiver for determining location information of the second mobile device;
• a plurality of radio transceivers for sending and receiving messages;
• a memory coupled to a processor for executing an emergency locator component operative to:
• receive a locator activation request to at least temporarily activate one or more of the plurality of radio transceivers of the second mobile communication device;
• receive the emergency location request message from the first mobile device using one or more of the activated transceivers;
• determine from the unique identifier of the mobile communication device and the received signal strength indication (RSSI) value whether to respond to the emergency location request message;
• and
• if an emergency location response is to be sent in reply to the emergency location request message, send the emergency location response message comprising location information using position data from the GPS receiver as well the information for determining the distance estimate to enable the first device to determine its location.