Enhanced cell ID location method using non uniform subsectors and neighboring cell centroid

1. A method of determining the location of a mobile device comprising the steps of:

(a) receiving measurement information from cells neighboring the serving cell and range information from the serving cell;

(b) dividing the serving cell into a plurality of subsectors;

(c) placing candidate locations on an intersection of bisectors of the plurality of subsectors and a range determined using the range information;

(d) selecting a subset of neighboring and serving cells as a function of the measurement information;

(e) determining a radio frequency (RF) coverage centroid for each of the selected neighboring cells;

(f) determining a centroid of the determined RF centroids based on a weighted average of selected neighboring cell centroids, wherein each of the weights of the weighted average vary as a function of at least one of a neighboring cell power level, a serving cell power level and an inter-site distance between neighboring cells and serving cells;

(g) determining a location of the target mobile device as the candidate location having a minimum distance to the determined centroid.

2. The method of claim 1 wherein the measurement information is selected from the group consisting of an absolute received signal power level observed at the target mobile device, a ratio of received signal power to maximum received power, and combinations thereof.

3. The method of claim 1 wherein the step of selecting a subset of neighboring and serving cells further comprises weighting measurement information for one or more of the neighboring and serving cells as a function of cell size.

4. The method of claim 1 further comprising the step of determining radial or angular uncertainties of the mobile device location.

5. The method of claim 1 wherein one determined RF centroid is a midpoint of the RF coverage area of the serving cell.

6. The method of claim 1 wherein one determined RF centroid is a function of values selected from the group consisting of antenna pattern, transmit power of the broadcast signal from a neighboring or serving cell, and combinations thereof.

7. The method of claim 1 , wherein the RF coverage centroid for each of the selected neighboring cells is spaced apart from base stations that serve the neighboring cells.

8. A method of determining the location of a mobile device comprising the steps of:

(a) receiving measurement information from cells neighboring the serving cell and range information from the serving cell;

(b) dividing the serving cell into a plurality of subsectors;

(c) placing candidate locations on an intersection of bisectors of the plurality of subsectors and a range determined using the range information;

(d) selecting a subset of neighboring and serving cells as a function of the measurement information;

(e) determining a radio frequency (RF) coverage centroid for each of the selected neighboring cells;

(f) determining a centroid of the determined RF centroids;

(g) determining a location of the target mobile device as the candidate location having a minimum distance to the determined centroid;

wherein the step of selecting a subset of neighboring and serving cells further comprises weighting measurement information for one or more of the neighboring and serving cells as a function of cell size;

wherein cell size is determined as a function of transmission power level of the respective cell, timing advance values from mobile devices within the respective cell, and combinations thereof.

9. A method of determining the location of a mobile device comprising the steps of:

(a) receiving measurement information from cells neighboring the serving cell and range information from the serving cell;

(b) dividing the serving cell into a plurality of subsectors;

(c) placing candidate locations on an intersection of bisectors of the plurality of subsectors and a range determined using the range information;

(d) selecting a subset of neighboring and serving cells as a function of the measurement information;

(e) determining a radio frequency (RF) coverage centroid for each of the selected neighboring cells;

(f) determining a centroid of the determined RF centroids;

(g) determining a location of the target mobile device as the candidate location having a minimum distance to the determined centroid;

(h) determining a radial uncertainty of the mobile device location, wherein the radial uncertainty is determined as a function of type of range information.

10. A method of determining the location of a mobile device comprising the steps of:

(a) receiving measurement information from cells neighboring the serving cell and range information from the serving cell;

(b) dividing the serving cell into a plurality of subsectors;

(c) placing candidate locations on an intersection of bisectors of the plurality of subsectors and a range determined using the range information;

(d) selecting a subset of neighboring and serving cells as a function of the measurement information;

(e) determining a radio frequency (RF) coverage centroid for each of the selected neighboring cells;

(f) determining a centroid of the determined RF centroids;

(g) determining a location of the target mobile device as the candidate location having a minimum distance to the determined centroid;

(h) determining an angular uncertainty of the mobile device location, wherein the angular uncertainty is determined as a function of the selected subsector.

11. A method of determining the location of a mobile device comprising the steps of:

(a) receiving measurement information from cells neighboring the serving cell and range information from the serving cell;

(b) dividing the serving cell into a plurality of subsectors;

(c) placing candidate locations on an intersection of bisectors of the plurality of subsectors and a range determined using the range information;

(d) selecting a subset of neighboring and serving cells as a function of the measurement information;

(e) determining a radio frequency (RF) coverage centroid for each of the selected neighboring cells;

(f) determining a centroid of the determined RF centroids;

(g) determining a location of the target mobile device as the candidate location having a minimum distance to the determined centroid;

wherein the step of determining a centroid of the determined RF centroids further comprises performing an unequally weighted average of selected neighboring cell centroids;

wherein the weights are a function of values selected from the group consisting of neighboring cell power level, serving cell power level, inter-site distance between neighboring and serving cells, and combinations thereof.