Locationing system performance in non-line of sight conditions

1. A system for improved locationing system performance in non-line of sight conditions of a mobile communication device within an environment, the system comprising:

a model of the environment including a map of a plurality of fixed transmitters within the environment, the model also includes a map of objects positioned within the environment that are capable of obstructing the signals from the transmitters, and includes mapped areas where the signal from a nearby transmitter is obstructed;

a locationing engine operable to track a location of a mobile communication device moving within the environment using the signals, determine that the mobile communication device is moving into a mapped area having an obstructed signal from a nearby transmitter to be used for locating the mobile communication device, modify a locationing system parameter for that obstructed signal, and locate the mobile communication device using at least the modified signal parameter; and

wherein the locationing engine modifies the locationing system parameter includes one of (a) calculating an accurate line of sight distance based on transposing a mirror image of a reflected signal path measurement, (b) weighting the obstructed signal less than signals in a line-of-sight condition, and (c) increasing a transmit power level of the obstructed signal from the transmitter, and (d) decreasing a signal detection threshold in the mobile communication device.

2. The system of claim 1 , wherein the locationing engine modifies the locationing system parameter by increasing the transmit power level of the obstructed signal from the transmitter until an amplitude of the obstructed signal measures above a signal detection threshold in the mobile communication device.

3. The system of claim 1 , wherein the locationing engine modifies the locationing system parameter by decreasing a transmit power level of the signal from the transmitter when it is in a line-of-sight condition with the mobile communication device.

4. The system of claim 1 , wherein the locationing engine modifies the locationing system parameter by decreasing the signal detection threshold in the mobile communication device so that the obstructed signal can be detected by the mobile communication device.

5. The system of claim 3 , wherein the locationing engine modifies the locationing system parameter by increasing a signal detection threshold in the mobile communication device when the obstructed transmitter returns to a line-of-sight condition with the mobile communication device.

6. A system for improved locationing system performance in non-line of sight conditions of a mobile communication device within an environment, the system comprising:

a model of the environment including a map of a plurality of fixed transmitters within the environment, the model also includes a map of objects positioned within the environment that are capable of obstructing the signals from the transmitters, and includes mapped areas where the signal from a nearby transmitter is obstructed;

a locationing engine operable to track a location of a mobile communication device moving within the environment using the signals, determine that the mobile communication device is moving into a mapped area having an obstructed signal from a nearby transmitter to be used for locating the mobile communication device, modify a locationing system parameter for that obstructed signal, and locate the mobile communication device using at least the modified signal parameter; and

wherein the locationing engine modifies the locationing system parameter by changing between flight time mode and RSSI mode signals for locationing of the mobile communication device.

7. The system of claim 1 , wherein the transmitters are radio frequency transmitters of a local area network and the signals are beacons used for locationing of the mobile communication device.

8. The system of claim 1 , wherein the transmitters are ultrasonic emitters and the signals are ultrasonic bursts used for locationing of the mobile communication device.

9. The system of claim 7 , wherein the transmitters can be affixed to a ceiling of the environment and oriented towards a floor of the environment to provide a limited region for the mobile communication devices to receive the ultrasonic bursts, the ultrasonic bursts have a frequency between 19 kHz and 22.05 kHz, and the mobile communication device utilizes existing, unmodified audio circuitry to measure the signals from the ultrasonic bursts.

10. A locationing engine having improved locationing system performance in non-line of sight conditions of a mobile communication device within an environment, the engine comprising:

a model of the environment including a map of a plurality of fixed transmitters within the environment, the model also includes a map of objects positioned within the environment that are capable of obstructing the signals from the transmitters, and includes mapped areas where the signal from a nearby transmitter is obstructed; and

a processor operable to track a location of a mobile communication device moving within the environment using the signals, determine that the mobile communication device is moving into a mapped area having an obstructed signal from a nearby transmitter to be used for locating the mobile communication device, modify a locationing system parameter for that obstructed signal, and locate the mobile communication device using at least the modified signal parameter;

wherein the processor operable to modify a locationing system parameter includes the processor configured for one of (a) calculating an accurate line of sight distance based on transposing a mirror image of a reflected signal path measurement, (b) weighting the modified locationing system parameter for the obstructed signal less than signals in a line-of-sight condition, (c) adapting a transmit power level of the obstructed signal from the transmitter, (d) adapting a signal detection threshold in the mobile communication device, and (e) changing between flight time mode and RSSI mode signals for the locationing step.

11. A method for improved locationing system performance in non-line of sight conditions of a mobile communication device within an environment, the method comprising the steps of:

providing a model of the environment including a map of a plurality of fixed transmitters within the environment, the model also includes a map of objects positioned within the environment that are capable of obstructing the signals from the transmitters, and includes mapped areas where the signal from a nearby transmitter is obstructed;

tracking a location of a mobile communication device moving within the environment using the signals from the plurality of fixed transmitters within the environment;

determining that the mobile communication device is moving into a mapped area having an obstructed signal from a nearby transmitter to be used for locating the mobile communication device;

modifying a locationing system parameter for that obstructed signal;

locationing of the mobile communication device using at least the modified signal parameter; and

wherein the modifying includes one of (a) calculating an accurate line of sight distance based on transposing a mirror image of a reflected signal path measurement, (b) weighting the modified locationing system parameter for the obstructed signal less than signals in a line-of-sight condition, (c) adapting a transmit power level of the obstructed signal from the transmitter, (d) adapting a signal detection threshold in the mobile communication device, and (e) changing between flight time mode and RSSI mode signals for the locationing step.

12. The method of claim 11 , wherein modifying includes adapting the transmit power level of the obstructed signal from the transmitter until an amplitude of the obstructed signal measures above a signal detection threshold in the mobile communication device.

13. The method of claim 11 , wherein modifying includes adapting the signal detection threshold in the mobile communication device so that the obstructed signal can be detected by the mobile communication device.