Apparatus and method for power measurement summation in mobile telecommunications system user equipment

• US 20070060191A1
• Filed: 09/09/2005
• Published: 03/15/2007
• Est. Priority Date: 09/09/2005
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: M-Stack Limited (Blackberry Limited)
• Inventors: Farnsworth, Andrew, Funnell, Nicola, Cheung, Nelson
• Granted Patent: US 7,826,864 B2
• Time in Patent Office: Days
• US Class Current: 455/525
• CPC Class Codes: H04B 17/318 Received signal strength

Abstract

Apparatus and a method for deriving a power measurement summation for use in universal mobile telecommunications system user equipment are disclosed. Conversion from a logarithm scale to a linear scale for summation and back again is avoided. The technique obviates the need for a mathematical processor to convert power measurements in a logarithmic scale (e.g. decibels dB, or dBw) into a linear scale (e.g. mW) to sum the power measurements or a ratio. The summed power component is calculated using data stored in the device (e.g. look up tables) without any need for conversion of the scale used.

Claims

1. A method for deriving a power measurement summation for use in a mobile telecommunications system, the system comprising a network of a plurality of cells and at least one user equipment device, the method comprising, in the user equipment:

receiving for each cell in a group of cells a power measurement, said power measurement being of a logarithmic scale;

determining from data stored in the user equipment a corresponding value for the power measurement on a linear scale of measurement,

summing the values.

2. A method according to claim 1 further comprising

for each cell:

deriving a unit parameter dependent upon the power measurement;

deriving a factor parameter dependent upon the power measurement;

deriving a value parameter dependent upon the unit parameter;

having derived the unit, factor and value parameters for each cell, adjusting the value parameter and the associated factor parameter for each cell to cause the factor parameters for each cell to become the same;

summing the adjusted value parameters for the cells to generate a group value parameter and an associated group factor parameter;

adjusting the group value parameter and the group factor parameter to cause the group value parameter to fall within a given range;

deriving a group unit parameter dependent upon the adjusted group value parameter; and

deriving a power measurement summation dependent on the group unit parameter and the adjusted group factor parameter.

3. A method according to claim 2 wherein the unit parameter is derived from d modulus 10, where d is the power from a cell in decibels.

4. A method according to claim 2 wherein the factor parameter is derived from d/10, where d is the power from a cell in decibels.

5. A method according to claim 2 wherein the value is parameter is derived by looking up the value parameter in a look up table for a given unit parameter.

6. A method according to claim 2 wherein the power measurement summation is of the form

7. A method according to claim 2 wherein the power measurement summation is of the form

8. A method according to claim 1 further including the step of excluding from the group of cells any cells the power of which is below a threshold dependent on the power measurement of the strongest cell.

9. A method according to claim 8 wherein, for N cells in an active list and an overall inaccuracy toleration of Z dBm, excluding any cells which are within 10×

Log(10<sup>(Z/(N−

1))10</sup>−

1) of the strongest cell in the active set.

10. A computer program product arranged when run to implement the method of claim 1.

11. Apparatus for deriving a power measurement summation for use in a mobile telecommunications system, the system comprising a network of a plurality of cells and at least one user equipment device, the apparatus comprising, in the user equipment, a processor arranged, in use, to carry out the following steps:

receiving for each cell in a group of cells a power measurement, said power measurement being of a logarithmic scale;

determining from data stored in the user equipment a corresponding value for the power measurement on a linear scale of measurement,

summing the values.

12. Apparatus according to claim 11 wherein the processor is further arranged, in use, to carry out the following steps

for each cell:

deriving a unit parameter dependent upon the power measurement;

deriving a factor parameter dependent upon the power measurement;

deriving a value parameter dependent upon the unit parameter;

having derived the unit, factor and value parameters for each cell, adjusting the value parameter and the associated factor parameter for each cell to cause the factor parameters for each cell to become the same;

summing the adjusted value parameters for the cells to generate a group value parameter and an associated group factor parameter;

adjusting the group value parameter and the group factor parameter to cause the group value parameter to fall within a given range;

deriving a group unit parameter dependent upon the adjusted group value parameter; and

deriving a power measurement summation dependent on the group unit parameter and the adjusted group factor parameter.

13. Apparatus according to claim 12 wherein the unit parameter is derived from d modulus 10, where d is the power from a cell in decibels.

14. Apparatus according to claim 12 wherein the factor parameter is derived from d/10, where d is the power from a cell in decibels.

15. Apparatus according to claim 12 wherein the value is parameter is derived by looking up the value parameter in a look up table for a given unit parameter.

16. Apparatus according to claim 12 wherein the power measurement summation is of the form

17. Apparatus according to claim 12 wherein the power measurement summation is of the form

18. Apparatus according to claim 11 further including the step of excluding from the group of cells any cells the power of which is below a threshold dependent on the power measurement of the strongest cell.

19. Apparatus according to claim 18 wherein, for N cells in an active list and an overall inaccuracy toleration of Z dBm, excluding any cells which are within 10×

Log(10<sup>(Z/(N−

1))/10</sup>−

1) of the strongest cell in the active set.

20. Apparatus according to claim 11 wherein the apparatus is a handheld electronic device.

21. A method for deriving a power measurement summation for use in a mobile telecommunications system, the system comprising a network of a plurality of cells and at least one user equipment device, the method comprising, in the user equipment:

receiving for each cell in a group of cells a power measurement,

excluding from the summation any cells the power of which is below a threshold determined by the power measurement of the strongest cell.

22. A method according to claim 21 wherein, for N cells in a group of cells and an overall inaccuracy toleration of Z dBm, excluding any cells which are within 10×

Log(10<sup>(Z/(N−

1))/10</sup>−

1) of the strongest cell in the group of cells.

25. A computer program product arranged when run to implement the method of claim 21.

23. Apparatus for deriving a power measurement summation for use in a mobile telecommunications system, the system comprising a network of a plurality of cells and at least one user equipment device, the apparatus comprising, in the user equipment, a processor arranged, in use, to carry out the following steps:

receiving for each cell in a group of cells a power measurement,

excluding from the summation any cells the power of which is below a threshold determined by the power measurement of the strongest cell.

24. Apparatus according to claim 23 wherein, for N cells in a group of cells and an overall inaccuracy toleration of Z dBm, excluding any cells which are within 10×

Log(10<sup>(Z/(N−

1))/10</sup>−

1) of the strongest cell in the group of cells.