METHOD AND SYSTEM FOR SELECTING OPTIMAL SATELLITES FOR A-GPS LOCATION OF HANDSETS IN WIRELESS NETWORKS

1 . A method comprising:

determining a first number of satellites that are searchable by the wireless device;

determining a second number of satellites visible from a boundary of an approximate area containing the wireless device;

determining a third number of satellites to be removed from a set of satellites searched for by the wireless device;

determining a plurality of sets of satellites as a function of the first, second and third numbers; and

selecting an optimum set of satellites of the plurality of sets of satellites as a function of the visibility of each of the plurality of sets of satellites at predetermined points substantially on the boundary.

2 . The method of claim 1 , wherein the optimum set of satellites has a maximum number of satellites in view from each of the one or more predetermined points.

3 . The method of claim 1 , wherein the optimum set of satellites is selected as a function of the relationship:

f satsViewBased =Σ i=1 noPo int s noSatsInView i ≧Z ×noSatsInView i : 0);

wherein noSatsIn View i represents a fourth number of satellites visible for each point selected substantially on the boundary of the approximate area; and

Z represents a minimum number of satellites visible from the approximate area.

4 . The method of claim 1 , wherein the boundary defines an area selected one of a city, municipality, county, state, country, continent, a serving area of a base station serving the wireless device and an approximate area of a communications network.

5 . The method of claim 1 , wherein the satellites are part of a Global Navigation Satellite System (“GNSS”).

6 . The method of claim 1 , wherein the wireless device is a cellular phone.

7 . The method of claim 1 , further comprising determining the location of the wireless device based on a signal received from each satellite in the optimum set of satellites.

8 . A wireless device comprising a computing device, the wireless device being configured to:

determine a boundary for an approximate area in which a wireless device is located;

determine an optimum set of satellites from a plurality of sets of satellites based on a satellite selection function at predetermined points substantially on the boundary; and

determine the location of the wireless device based on signals received from the optimum set of satellites.

9 . The wireless devices of claim 8 , wherein the wireless device is further configured to:

determine a first number of satellites searchable by the wireless device;

determine a second number of satellites visible from the approximate area;

determine a third number of satellites to be removed from the plurality of sets of satellites; and

determine the plurality of sets of satellites as a function of the first, second and third numbers.

10 . The wireless device of claim 9 , wherein the optimum set of satellites has a maximum number of satellites in view from each of the one or more predetermined points.

11 . The wireless device of claim 10 , wherein the optimum set of satellites is determined as a function of the relationship:

f satsViewBased =Σ i=1 noPo int s noSatsInView i ≧Z ×noSatsInView i : 0);

wherein:

noSatsInView i represents a fourth number of satellites visible for each point (i) selected substantially on the boundary of the approximate area; and

Z represents a minimum number of satellites visible from the approximate area.

12 . The wireless device of claim 9 , wherein the optimum set of satellites has a minimum dilution of precision (DOP) for satellites in view from each of the one or more predetermined points.

13 . The wireless device of claim 12 , wherein the optimum set of satellites is determined as a function of the relationship:

f DOPBased =Σ i=1 noPo int s DOP i o;

wherein DOP i is the DOP for satellites in view at each point (i) selected substantially on the boundary of the approximate area.

14 . A non-transitory machine readable medium comprising a location information system, the location information system being configured to:

determine a boundary for an approximate area in which a wireless device is located;

determine an optimum set of satellites from one or more sets of satellites visible within the boundary based on a satellite selection function at predetermined points substantially on the boundary; and

transmit assistance data that includes the optimum set of satellites to a global positioning system (GPS) receiver operating on the wireless device.

15 . The medium of claim 14 , wherein the satellite selection function is defined as:

f satsViewBased =Σ i=1 noPo int s noSatsInView i ≧Z ×noSatsInView i : 0);

wherein:

noSatsInView i represents a number of satellites visible from each point (i) selected substantially on the boundary of the approximate area; and

Z represents a minimum number of satellites visible from the approximate area.

16 . The medium of claim 14 , wherein the boundary defines an area selected from one of a city, municipality, county, state, country, continent, a serving area of a base station serving the wireless device and an approximate area of a communications network.

17 . The medium of claim 14 , wherein the satellites are part of a Global Navigation Satellite System (“GNSS”).

18 . The medium of claim 14 , wherein the wireless device is a cellular phone.

19 . The medium of claim 14 , wherein the optimum set of satellites has a minimum dilution of precision (DOP) for satellites in view from each of the one or more predetermined points.

20 . The medium of claim 19 , the wherein the satellite selection function is defined as:

f DOPBased =Σ i=1 noPo int s DOP i o;

wherein DOP i is the DOP for satellites in view at each point (i) selected substantially on the boundary of the approximate area.