Method and apparatus for storing frequencies

1. A method of operating a wireless communications apparatus, the method comprising:

comparing the value of a previously used frequency with a frequency raster of a parameter storage area to identify whether the value of a previously used cell frequency is incompatible with the frequency raster of the parameter storage area;

responsive to identifying the incompatibility:

performing an arithmetical operation on the value of the incompatible previously used frequency to give a modified value of the previously used cell frequency lying within one of at least one predetermined range compatible with the frequency raster of the parameter storage area; and

storing the modified value of the previously used cell frequency in the parameter storage area.

2. The method as claimed in claim 1 , wherein the previously used cell frequency is identified as incompatible because it lies on a 100 kHz raster.

3. The method as claimed in claim 1 , wherein the previously used cell frequency is identified as incompatible because the result of dividing it by 200 kHz is not a whole number value.

4. The method as claimed in claim 1 , wherein the arithmetical operation is to add a constant.

5. The method as claimed in claim 4 , wherein the constant is positive.

6. The method as claimed in claim 5 , wherein the constant is greater than any frequency the wireless communications apparatus is arranged to use for radio communication.

7. The method as claimed in claim 4 , wherein the constant is negative.

8. The method as claimed in claim 7 , wherein the constant has a value which results in an incompatible frequency being stored as a value which is less than any frequency the wireless communications apparatus is arranged to use for radio communication.

9. The method as claimed in claim 1 , wherein the arithmetical operation is dependent upon the value of the previously used cell frequency.

10. The method as claimed in claim 1 , wherein the arithmetical operation is independent of the value of the previously used cell frequency.

11. The method as claimed in claim 1 , wherein the wireless communications apparatus is arranged to communicate with a UMTS network and the parameter storage area is EF NETPAR .

12. A computer program product comprising code means stored on a non-transitory computer readable medium for performing the steps of the method of claim 1 .

13. A computer operating under the instructions of a computer program product comprising code means stored on a non-transitory computer readable medium as claimed in claim 12 .

14. A wireless communications apparatus comprising:

a parameter storage area for storing a previously used cell frequency; and

a processor configured to:

compare the value of the previously used cell frequency with a frequency raster of the parameter storage area to identify whether the value of the previously used cell frequency is incompatible with the frequency raster of the parameter storage area; and

responsive to identifying the incompatibility:

perform an arithmetical operation on the value of the incompatible previously used cell frequency to give a modified value of the previously used cell frequency lying within one of at least one predetermined range compatible with the frequency raster of the parameter storage area; and

store the modified value of the previously used cell frequency in the parameter storage area.

15. A method, in a wireless communications apparatus, the method comprising:

reading a stored value of a previously used cell frequency from a parameter storage area;

identifying whether the stored value is compatible with a network within which the apparatus is operable by determining whether the stored value is within one of at least one predetermined range;

responsive to determining the stored value is within one of at least one predetermined range compatible with the frequency raster of the parameter storage area:

performing an arithmetical operation on the stored value to give a corrected value of the previously used cell frequency, wherein the arithmetical operation is dependent upon the stored value of the previously used cell frequency; and

searching for a cell of the communication network at the corrected value of the previously used cell frequency.

16. The method as claimed in claim 15 , wherein the arithmetical operation is to subtract a constant.

17. The method as claimed in claim 16 , wherein the constant is positive.

18. The method as claimed in claim 17 , wherein the constant results in the corrected value of the previously used cell frequency being within a range of frequencies that the wireless communications apparatus is arranged to use for radio communication.

19. The method as claimed in claim 16 , wherein the constant is negative.

20. The method as claimed in claim 19 , wherein the constant results in the corrected value of the previously used cell frequency being within a range of frequencies that the wireless communications apparatus is arranged to use for radio communication.

21. The method as claimed in claim 15 , wherein the wireless communications apparatus is arranged to communicate with a UMTS network and the parameter storage area is EF NETPAR .

22. A computer program product comprising code means stored on a non-transitory computer readable medium for performing the steps of the method of claim 15 .

23. A computer operating under the instructions of a computer program product comprising code means stored on a non-transitory computer readable medium as claimed in claim 22 .

24. A wireless communications apparatus comprising:

a parameter storage area for storing a previously used cell frequency; and

a processor configured to

read the stored value of a previously used cell frequency from a parameter storage area;

identify whether the stored value is compatible with a network within which the apparatus is operable by determining whether the stored value is within one of at least one predetermined range compatible with the frequency raster of the parameter storage area;

responsive to determining the stored value is within one of at least one predetermined range:

perform an arithmetical operation on the stored value to give a corrected value of the previously used cell frequency, wherein the arithmetical operation is dependent upon the stored value of the previously used cell frequency; and

search for a cell of the communication network at the corrected value of the previously used cell frequency.