System and method for geographically locating a cellular phone
According to an embodiment of the invention, there is disclosed a method for geographically locating a cellular phone. The method comprises: determining an effective cell-area for each of a first cell and a second cell in a cellular network; and determining a handover area within which the cellular phone is likely to be located when control of the cellular phone is transferred from the first cell to the second cell; wherein the determination of the handover area and the effective cell-area for each of the first cell and the second cell are made based on a topological relationship between the first cell and the second cell. Further related apparatus embodiments are also disclosed.
1. A method of geographically locating a cellular phone, the method comprising:
determining that a handover of the cellular phone from a first cell to a second cell has occurred;
determining a geographical area in which the handover from the first cell to the second cell occurred by:
modeling at least a portion of a cell reception area of the first cell and the second cell;
defining a handover area comprising overlapping portions of the first and second cell areas; and
concluding that when the handover occurred the cellular phone was located in the handover area;
wherein modeling the at least a portion of the cell reception area of the first cell and the second cell comprises using a pre-defined shape as an initial model of at least a portion of the cell reception area of at least one of the first cell and the second cell.
2. The method according to claim 1 , further comprising:
determining whether to extend the cell reception area based on predetermined criteria.
3. The method according to claim 2 , wherein the predetermined criteria comprise criteria based on a relative orientation of the first cell and the second cell.
4. The method according to claim 2 , wherein the predetermined criteria comprise criteria based on relative positions of the first cell and the second cell.
5. The method according to claim 1 , wherein the pre-defined shape comprises a sector.
6. The method according to claim 1 , wherein the pre-defined shape comprises a ring-sector.
7. The method according to claim 1 , wherein defining the handover area comprises forming a polygon representing the handover area.
8. The method according to claim 1 , wherein defining the handover area comprises forming a penumbra area shape around a line of equal intensity of reception between the first cell and the second cell.
9. The method according to claim 8 , wherein the penumbra area shape comprises a polygon.
10. The method according to claim 9 , wherein the penumbra area shape comprises a rectangle.
11. An apparatus for geographically locating a cellular phone, the apparatus comprising:
means for determining that a handover of the cellular phone from a first cell to a second cell has occurred;
means for determining a geographical area in which the handover from the first cell to the second cell occurred, wherein the means for determining the area comprises:
an effective cell-area module for modeling at least a portion of a cell reception area of the first cell and the second cell;
a handover area module for defining a handover area comprising overlapping portions of the first and second cell areas; and
means for concluding that when that the handover occurred the cellular phone was located in the handover area;
wherein the effective cell-area module comprises means for modeling the at least a portion of the cell reception area of the first cell and the second cell using a pre-defined shape as an initial model of at least a portion of the cell reception area of at least one of the first cell and the second cell.
12. The apparatus according to claim 11 , wherein the effective cell-area module comprises means for determining whether to extend the cell reception area based on predetermined criteria.
13. The apparatus according to claim 12 , wherein the predetermined criteria comprise criteria based on a relative orientation of the first cell and the second cell.
14. The apparatus according to claim 12 , wherein the predetermined criteria comprise criteria based on relative positions of the first cell and the second cell.
15. The apparatus according to claim 11 , wherein the pre-defined shape comprises a sector.
16. The apparatus according to claim 11 , wherein the pre-defined shape comprises a ring-sector.
17. The apparatus according to claim 11 , wherein the handover area module comprises means for forming a polygon representing the handover area.
18. The apparatus according to claim 11 , wherein the handover area module comprises means for forming a penumbra area shape around a line of equal intensity of reception between the first cell and the second cell.
19. The apparatus according to claim 18 , wherein the penumbra area shape comprises a polygon.
20. The apparatus according to claim 19 , wherein the penumbra area shape comprises a rectangle.