Method and apparatus for selecting carriers

• US 7,120,437 B2
• Filed: 01/27/2003
• Issued: 10/10/2006
• Est. Priority Date: 02/21/2002
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Thomas, Howard, Benson, Maya
• Primary Examiner(s): Kincaid, Lester G.
• Assistant Examiner(s): LAM, DUNG LE
• Application Number:
  US10/500,628
• Publication Number:
  US 20050075074A1
• Time in Patent Office: 1,352 Days
• Field of Search: 455/434, 455/226.1, 455/67.11, 455/437, 455/161.3, 455/168.1
• US Class Current: 455/434
• CPC Class Codes: H04W 36/0088 Scheduling hand-off measurements
• 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 apparatus 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 having a number of receivers operable to measure carriers in a frequency band, the method comprising the steps of:

Dynamically determining a frequency of measurements updates when measuring carriers in the frequency band;

wherein the frequency of measurements updates is indicative of the amount of time required by the subscriber unit to measure the carriers and wherein the amount of time required to measure the carriers is dependent on how many receivers a subscriber unit have; and

Dynamically selecting a subset of carriers in the frequency band to be measured by the subscriber unit based on the frequency of measurement updates which is dependent on the frequency of measurement updates, which in turn is based on the number of receivers in a subscriber unit.

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 frequency of measurement updates is indicative of the number of receivers in the subscriber unit.

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

6. 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.

7. A method of selecting carriers as claimed in claim 6 wherein the cellular communication system is a GSM communication system and the second communication system is a UMTS communication system.

8. A method of selecting carriers as claimed in claim 6 wherein the cellular communication system is a UMLTS communication system and the second communication system is a GSM communication system.

9. A method of selecting carriers as claimed in claim 6 wherein an update frequency capability of the subscriber unit is determined from a subscriber unit capability report indicating if compressed mode is required to perform measurements on a GSM communication system.

10. A method of selecting carriers as claimed in claim 1 wherein the size of the subset of carriers is dependent on an update frequency capability of the subscriber unit.

11. 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 an update frequency capability of the subscriber unit.

12. 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.

13. A method of selecting carriers as claimed in claim 1 wherein the frequency of measurement updates is determined from the number of measurement reports reported from the subscriber unit within a given time interval.

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

Means for dynamically determining a frequency of measurements updates when measuring carriers in the frequency band;

wherein the frequency of measurements updates is indicative of the amount of time required by the subscriber unit to measure the carriers and wherein the amount of time required to measure the carriers is dependent on how many receivers a subscriber unit have; and

Means for dynamically selecting a subset of carriers in the frequency band to be measured by the subscriber unit based on the frequency of measurement updates which is dependent on the frequency of measurement updates, which in turn is based on the number of receivers in a subscriber unit.

15. An apparatus as claimed in claim 14 further comprising means for transmitting identification of the subset of carriers to the subscriber unit.

16. An apparatus as claimed in claim 14 wherein the frequency of measurement updates is indicative of the number of receivers in the subscriber unit.

17. An apparatus as claimed in claim 14 wherein the frequency band is a frequency band of a second communication system.

18. An apparatus as claimed in claim 17 wherein the cellular communication system and the second communication system use different radio access technologies.

19. An apparatus as claimed in claim 18 wherein the cellular communication system is a GSM communication system and the second communication system is a UMTS communication system.

20. An apparatus as claimed in claim 18 wherein the cellular communication system is a UMTS communication system and the second communication system is a GSM communication system.

21. An apparatus as claimed in claim 18 wherein the means for determining is operable to determine an update frequency capability of the subscriber unit from a subscriber unit capability report indicating if compressed mode is required to perform measurements on a GSM communication system.

22. An apparatus as claimed in claim 14 further comprising means for determining a handover candidate carrier from the subset of carriers.

23. An apparatus as claimed in claim 14 wherein the means for determining is operable to determine the frequency of measurement updates from the number of measurement reports reported from the subscriber unit within a given time interval.

24. A cellular communication system comprising the apparatus of claim 14.

25. A subscriber unit for selecting carriers to be measured by a subscriber unit served by a cellular communication system and having a number of receivers operable to measure carriers in a frequency band, the method comprising the steps of:

means for dynamically determining a frequency of measurements updates when measuring carriers in the frequency band;

wherein the frequency of measurements updates is indicative of the amount of time required by the subscriber unit to measure the carriers and wherein the amount of time required to measure the carriers is dependent on how many receivers a subscriber unit have; and

means for dynamically selecting a subset of carriers in the frequency band to be measured by the subscriber unit based on the frequency of measurement updates which is dependent on the frequency of measurement updates, which in turn is based on the number of receivers in a subscriber unit.

26. A subscriber unit as claimed in claim 25 wherein the frequency of measurement updates is indicative of the number of receivers in the subscriber unit.

27. A subscriber unit as claimed in claim 25 wherein the frequency band is a frequency band of a second communication system.

28. A subscriber unit as claimed in claim 25 wherein the cellular communication system and the second communication system use different radio access technologies.

29. A subscriber unit as claimed in claim 28 wherein the cellular communication system is a GSM communication system and the second communication system is a UMTS communication system.

30. A subscriber unit as claimed in claim 28 wherein the cellular communication system is a UMTS communication system and the second communication system is a GSM communication system.

31. A subscriber unit as claimed in claim 25 further comprising means for determining a handover candidate carrier from the subset of carriers.