Method and apparatus for enhanced 911 location using power control in a wireless system

A method of locating a mobile telephone, comprising:

• receiving at a base station a signal from a mobile telephone;
• invoking a location function in response to the signal;
• determining whether the mobile telephone should increase power for location determination;
• transmitting from the base station to the mobile telephone a control message instructing the mobile telephone to transmit a TDMA signal at an increased power level based on the determining;
• receiving at least one of a plurality of base stations the TDMA signal transmitted at the increased power level;
• and
• calculating a location of the mobile telephone based on the TDMA signal received at at least one of the plurality of base stations.

A method of locating a mobile telephone, comprising:

• receiving a dialed number in a first signal having a first power level;
• determining whether the dialed number triggers a location function;
• initiating a mobile telephone call to the dialed number;
• transmitting known data to a mobile telephone system for location determination at increased power level when the location function is determined to be triggered;
• receiving in response to the known data a second signal from the mobile telephone, the second signal having a higher power level than the first signal, the second signal comprising pre-specified data to assist in location determination;
• and
• applying the higher power level of the second signal to perform the location determination triggered by receipt of the dialed number.

An apparatus for locating a mobile telephone, comprising:

• a plurality of base stations communicating TDMA signals with a mobile telephone;
• a mobile switching center, coupled with the plurality of base stations, the mobile switching center a) receiving from one of the plurality of base stations a call that includes a dialed number of the mobile telephone, b) determining whether the dialed number invokes a location function, and c) sending an instruction to the mobile telephone via one of the plurality of base stations to increase transmission power when the location function is invoked;
• and
• a location processor, coupled with the plurality of base stations and the mobile switching center, the location processor determining the location of the mobile telephone based on the TDMA signals received from the mobile telephone via at least one of the plurality of base stations at the increased power level.

A method comprising:

• instructing a mobile device to place a call;
• the mobile device determining whether location determination is to be performed for the call;
• the mobile device transmitting the call at a highest power level available for calls from the mobile device when location determination is to be performed for the call, the mobile device transmitting the call at a lower power level otherwise;
• and
• the mobile device transmitting pre-specified data during the call when the call is transmitted at a highest power level, the pre-specified data selected to assist in location determination.

A method of locating a mobile telephone, comprising:

• receiving at a first base station a request from a mobile device to perform location determination for the mobile device;
• invoking a location function in response to the signal;
• determining whether the mobile device should increase power for location determination;
• when the mobile device should increase power, transmitting from the base station to the mobile device a control message instructing the mobile device to transmit a signal at a highest power level;
• receiving at at least one of a plurality of base stations the highest power level;
• and
• calculating a location of the mobile device based on the signal received at the at least one of the plurality of base stations, the signal comprising pre-specified data selected to assist in location determination.

An apparatus for locating a mobile telephone, comprising:

• a plurality of base stations communicating signals with a mobile telephone;
• a mobile switching center, coupled with the plurality of base stations, the mobile switching center a) receiving from one of the plurality of base stations a call that includes a dialed number of the mobile telephone, b) determining whether the dialed number invokes a location function, and c) sending an instruction to the mobile telephone via one of the plurality of base stations to increase transmission power and to provide pre-specified data when the location function is invoked;
• and
• a location processor, coupled with the plurality of base stations and the mobile switching center, the location processor determining the location of the mobile telephone based at least in part on the pre-specified data received from the mobile telephone via at least one of the plurality of base stations at the increased power level.