Method and apparatus for selecting carriers

• US 20050075074A1
• Filed: 01/27/2003
• Published: 04/07/2005
• Est. Priority Date: 02/21/2002
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Thomas, Howard, Benson, Maya
• Granted Patent: US 7,120,437 B2
• Time in Patent Office: Days
• US Class Current: 455/67.110
• CPC Class Codes: H04W 36/0088 Scheduling hand-off measurements
• CPC Class Codes: H04W 36/14 Reselecting a network or an air interface
• CPC Class Codes: H04W 36/1443 between licensed networks

Abstract

This invention relates to a method and apparatus for selecting carriers to be measured by a subscriber unit (301,303, 501). The subscriber unit (301, 303, 501) is served by a communication system and is operable to measure carriers in a frequency band, which typically belongs to a different communication system. The appratus comprises a performance processor (329) for determining a measuring performance characteristic of the subscriber unit (301, 303, 501) related to the measurement performance of the subscriber unit (301, 303, 501) when measuring in the frequency band. The apparatus furthermore comprises a carrier subset selector (331) for selecting a subset of carriers in the frequency band to be measured by the subscriber unit. The subset of carriers is selected dependent on the measuring performance characteristic. The invention is applicable to dual 2nd and 3rd generation cellular communication systems such as GSM/UMTS.

Claims

1. A method of selecting carriers to be measured by a subscriber unit served by a cellular communication system and operable to measure carriers in a frequency band, the method comprising the steps of

determining a measuring performance characteristic of the subscriber unit related to the measurement performance of the subscriber unit when measuring carriers in the frequency band;

and

selecting a subset of carriers in the frequency band to be measured by the subscriber unit in response to the measuring performance characteristic.

2. A method of selecting carriers as claimed in claim 1 further comprising the step of transmitting identification of the subset of carriers to the subscriber unit.

3. A method of selecting carriers as claimed in claim 1 further comprising the step of the subscriber unit measuring the carriers of the subset of carriers.

4. A method of selecting carriers as claimed in claim 1 wherein the measuring performance characteristic is indicative of the time required for the subscriber unit to measure carriers in the frequency band.

5. A method of selecting carriers as claimed in claim 1 wherein the measuring performance characteristic is indicative of the number of receivers in the subscriber unit.

6. A method of selecting carriers as claimed in claim 1 wherein the frequency band is a frequency band of a second communication system.

7. A method of selecting carriers as claimed in claim 1 wherein the cellular communication system and the second communication system use different radio access technologies.

8. A method of selecting carriers as claimed in claim 7 wherein the cellular communication system is a GSM communication system and the second communication system is a UMTS communication system.

9. A method of selecting carriers as claimed in claim 7 wherein the cellular communication system is a UMTS communication system and the second communication system is a GSM communication system.

10. A method of selecting carriers as claimed in claim 7 wherein the measuring performance characteristic is determined from a subscriber unit capability report indicating if compressed mode is required to perform measurements on a GSM communication system.

11. A method of selecting carriers as claimed in claim 1 wherein the size of the subset of carriers is dependent on the performance characteristic.

12. A method of selecting carriers as claimed in claim 1 wherein the subset of carriers is an ordered subset of carriers and the order of carriers in the subset of carriers is dependent on the performance characteristic.

13. A method of selecting carriers as claimed in claim 1 further comprising the step of determining a handover candidate carrier from the subset of carriers.

14. A method of selecting carriers as claimed in claim 1 wherein the measuring performance characteristic is determined from the number of measurement reports reported from the subscriber unit within a given time interval.

15. An apparatus for selecting carriers to be measured by a subscriber unit served by a cellular communication system and operable to measure carriers in a frequency band, the method comprising:

means for determining a measuring performance characteristic of the subscriber unit related to the measurement performance of the subscriber unit when measuring carriers in the frequency band; and

means for selecting a subset of carriers in the frequency band to be measured by the subscriber unit in response to the measuring performance characteristic.

16. An apparatus as claimed in claim 15 further comprising means for transmitting identification of the subset of carriers to the subscriber unit.

17. An apparatus as claimed in claim 15 wherein the measuring performance characteristic is indicative of the time required for the subscriber unit to measure carriers in the frequency band.

18. An apparatus as claimed in claim 15 wherein the measuring performance characteristic is indicative of the number of receivers in the subscriber unit.

19. An apparatus as claimed in claim 15 wherein the frequency band is a frequency band of a second communication system.

20. An apparatus as claimed in claim 19 wherein the cellular communication system and the second communication system use different radio access technologies.

21. An apparatus as claimed in claim 20 wherein the cellular communication system is a GSM communication system and the second communication system is a UMTS communication system.

22. An apparatus as claimed in claim 20 wherein the cellular communication system is a UMTS communication system and the second communication system is a GSM communication system.

23. An apparatus as claimed in claim 20 wherein the means for determining a measuring performance characteristic is operable to determine the measuring performance characteristic from a subscriber unit capability report indicating if compressed mode is required to perform measurements on a GSM communication system.

24. An apparatus as claimed in claim 15 further comprising means for determining a handover candidate carrier from the subset of carriers.

25. An apparatus as claimed in claim 15 wherein the means for determining a measuring performance characteristic is operable to determine the measuring performance characteristic from the number of measurement reports reported from the subscriber unit within a given time interval.

26. A cellular communication system comprising the apparatus of claim 15.

27. A subscriber unit operable to be served by a cellular communication system and to measure carriers in a frequency band, the subscriber unit comprising:

means for determining a measuring performance characteristic of the subscriber unit related to the measurement performance of the subscriber unit when measuring carriers in the frequency band; and

means for selecting a subset of carriers in the frequency band to be measured by the subscriber unit in response to the measuring performance characteristic; and

means for measuring the carriers of the subset of carriers.

28. A subscriber unit as claimed in claim 27 wherein the measuring performance characteristic is indicative of the time required for the subscriber unit to measure carriers in the frequency band.

29. A subscriber unit as claimed in claim 27 wherein the measuring performance characteristic is indicative of the number of receivers in the subscriber unit.

30. A subscriber unit as claimed in claim 27 wherein the frequency band is a frequency band of a second communication system.

31. A subscriber unit as claimed in claim 27 wherein the cellular communication system and the second communication system use different radio access technologies.

32. A subscriber unit as claimed in claim 31 wherein the cellular communication system is a GSM communication system and the second communication system is a UMTS communication system.

33. A subscriber unit as claimed in claim 31 wherein the cellular communication system is a UMTS communication system and the second communication system is a GSM communication system.

34. A subscriber unit as claimed in claim 27 further comprising means for determining a handover candidate carrier from the subset of carriers.