Method and apparatus for handover measurement

• US 20080146231A1
• Filed: 10/26/2007
• Published: 06/19/2008
• Est. Priority Date: 10/27/2006
• Status: Active Grant

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Nokia Corporation
• Inventors: Shu, Kodo, Huang, Leping, Chen, Hongyuan, Nielsen, Sari
• Granted Patent: US 8,095,134 B2
• Time in Patent Office: Days
• US Class Current: 455/436
• CPC Class Codes: H04B 17/27 for locating or positioning the transmitter
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04B 17/382 for resource allocation, admission control or handover
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04W 36/0088 Scheduling hand-off measurements
• CPC Class Codes: H04W 36/0094 Definition of hand-off measurement parameters
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 72/54 based on quality criteria

Abstract

A UE performs pilot measurements over a frequency sub-band of serving cell and adjacent cells based on pilot symbols for used in handover. UE uses channel quality measurement result to adjust frequency sub-band and periodicity of pilot measurement. In interference coordination scheme, UE is classified into cell edge or cell center UE based on channel quality measurement result. For downlink data reception, UE in cell edge is allocated cell edge frequency sub-band and UE in cell center is allocated with cell center frequency sub-band. If UE is in cell edge of the serving cell, UE also performs pilot measurement over cell edge frequency sub-band. If UE is in cell center, UE also performs pilot measurement over cell center frequency sub-band of the serving cell. When UE is located in cell edge, it performs measurement at a higher rate than when it is located in cell center.

Claims

1. A method, comprising:

processing pilot symbols in a user equipment device in a radio access network, the user equipment device located in a serving cell; and

performing handover measurement over a frequency sub-band of an operating bandwidth of the serving cell and one or more different frequency sub-bands of one or more cells adjacent to the serving cell based on the pilot symbols for obtaining a handover measurement result.

2. The method of claim 1, further comprising:

conveying the handover measurement result to a network component in the radio access network for deciding whether to carry out a handover event at least partly based on the handover measurement result.

3. The method of claim 2, wherein the serving cell has a cell-edge section and a cell-center section, said method further comprising:

measuring channel quality of the serving cell for obtaining a channel quality measurement result, and

determining whether the user equipment device is located in the cell-center section or in the cell-edge section at least partly based on the channel quality measurement result.

4. The method of claim 1, further comprising

measuring channel quality of the serving cell for obtaining a channel quality measurement result, and

determining said one or more different frequency sub-bands for performing the handover measurement on said one or more adjacent cells based on the channel quality measurement result.

5. The method of claim 1, wherein the serving cell has a cell-edge section and a cell-center section, and the frequency sub-band comprises a cell-edge frequency sub-band and a cell-center frequency sub-band, said method further comprising:

allocating the cell-edge frequency sub-band to the user equipment device for downlink data reception in the user equipment device when the user equipment device is located in the cell-edge section, and

allocating the cell-center frequency sub-band to the user equipment device for downlink data reception in the user equipment device when the user equipment device is located in the cell-center section.

6. The method of claim 5, wherein when the user equipment is located in the cell-edge section, the handover measurement is performed over the cell-edge frequency sub-band of the serving cell and said one or more different frequency sub-bands of the adjacent one or more cells.

7. The method of claim 1, wherein the serving cell has a cell-edge section and a cell-center section, and wherein

when the user equipment device is located in the cell-edge section of the serving cell, the handover measurement is performed with a first measurement rate, and

when the user equipment is located in the cell-center section of the serving cell, the handover measurement is performed with a second measurement rate smaller than the first measurement rate.

8. The method of claim 7, wherein the user equipment device has a moving speed, and wherein the first measurement rate is dependent upon the moving speed.

9. The method of claim 2, further comprising:

selecting one of said one or more cells for the handover event if the handover measurement result meets a predetermined criteria.

10. The method of claim 3, wherein the serving cell has a cell-edge section and a cell-center section, said method further comprising

determining whether the user equipment is located in the cell-center section or in the cell-edge section at least partly based on a frequency reuse pattern in the operation bandwidth.

11. An apparatus, comprising:

a receiver for receiving pilot symbols in a radio access network, wherein the apparatus is located in a serving cell in the radio access network; and

a measurement module configured for performing handover measurement over a frequency sub-band of serving cell and one or more different frequency sub-bands of one or more cells adjacent to the serving cell based on the pilot symbols for obtaining a handover measurement result.

12. The apparatus of claim 11, further comprising:

a transmitter for conveying the handover measurement result to a network component in the radio access network for deciding a handover event at least partly based on the handover measurement result.

13. The apparatus of claim 11, wherein the serving cell has a cell-edge section and a cell-center section, and wherein the measurement module is also configured for performing channel quality measurement of the serving cell for providing a channel quality measurement result so as to determine whether the apparatus is located in the cell-edge section or in the cell-center section based on the channel quality measurement result;

and wherein the handover measurement is performed at least partly based on whether the apparatus is located in the cell-edge section or located in the cell-center section.

14. The apparatus of claim 11, wherein said measurement module is also configured for performing channel quality measurement of the serving cell for providing a channel quality measurement result, said apparatus further comprising:

a determining module configured for determining, based on the channel quality measurement result, whether the handover measurement is carried out, and a time interval for the handover measurement.

15. The apparatus of claim 11, wherein

when the channel quality measurement result is equal to or higher than the predetermined quality value, performing the handover measurement with a longer time interval, and

when the channel quality measurement result is lower than the predetermined quality level, performing the handover measurement with a longer time interval.

16. The apparatus of claim 14, wherein the frequency sub-band and said one or more different frequency sub-bands are determined based on the channel quality measurement result.

17. A method, comprising:

measuring channel quality of a serving cell in a radio access network for obtaining a channel quality measurement result, wherein the radio access network comprises a serving cell and a plurality of adjacent cells adjacent to the serving cell, and a user equipment device located in the serving cell, and wherein the user equipment device is configured to receive and process pilot symbols; and

determining, based on the channel measurement result, whether a handover measurement based on the pilot symbols is carried out, and a time interval for performing the handover measurement.

18. The method of claim 17, wherein the channel quality measurement is indicative of the channel quality of the serving cell as compared to a predetermined quality value, and wherein

when the channel quality of the serving cell is equal to or higher than the predetermined quality value, performing the handover measurement with a longer time interval, and

when the channel quality of the serving cell is lower than the predetermined quality level, performing the handover measurement with a shorter time interval.

19. The method of claim 17, further comprising:

conveying the handover measurement result to a network component in the radio access network for deciding whether to carry out a handover event at least partly based on the handover measurement result.

20. The method of claim 18, wherein the serving cell has a cell-edge section and a cell-center section, said method further comprising:

determining whether the user equipment device is located in the cell-center section or in the cell-edge section, wherein said handover measurement is performed at least partly based on said determining.

21. The method of claim 20, further comprising;

measuring channel quality for determining whether the user equipment device is located in the cell-center section or in the cell-edge section at least partly based on said measuring.

22. The method of claim 18, wherein

when the user equipment device is located in the cell-edge section of the serving cell, the handover measurement is performed with a first measurement rate, and

when the user equipment is located in the cell-center section of the serving cell, the handover measurement is performed with a second measurement rate smaller than the first measurement rate.

23. The method of claim 22, wherein the user equipment device has a moving speed, and wherein the first measurement rate is dependent upon the moving speed.

24. The method of claim 19, further comprising:

selecting one of said one or more cells for the handover event if the handover measurement result meets a predetermined criteria.

25. The method of claim 20, further comprising

determining whether the user equipment is located in the cell-center section or in the cell-edge section at least partly based on a frequency reuse pattern.

26. A wireless communications network comprising:

a first network component, and

a second network component configured for communication with the first network component, wherein the first network component is located in a first cell adjacent to one or more second cells, each of the first and second cells having a frequency sub-band, and wherein the first network component comprises;

means for receiving pilot symbols in a radio access network, wherein the first network component is located in a serving cell of the radio access network and

means for performing handover measurement over a frequency sub-band of serving cell and one or more cells adjacent to the serving cell based on the pilot symbols, based on the received pilot symbols, and for providing handover measurement result to the second network component; and

the second network component is configured for deciding whether to carry out a handover event for the first network component at least partly based on the handover measurement results.

27. The wireless communication network of claim 26, wherein the serving cell has a cell-edge section and a cell center section, and wherein the handover measurement is performed at least partly based on whether the first network component is located in the cell-edge section or located in the cell-center section.