METHODS AND APPARATUS FOR CELL SELECTION

• US 20150023283A1
• Filed: 03/14/2012
• Published: 01/22/2015
• Est. Priority Date: 03/14/2012
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Liu, Jinhua, Gu, Xinyu, Miao, Qingyu, Grant, Stephen
• Granted Patent: US 9,439,138 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04L 5/0035 Resource allocation in a cooperative multipoint environment
• CPC Class Codes: H04W 36/0069 in case of dual connectivity, e.g. decoupled uplink/downlink
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access

Abstract

The present disclosure relates to a cell selection scheme. In one embodiment, there provides a method for performing a cell selection for a UE at a primary serving cell of the UE in a CoMP cluster including the primary serving cell and one or more candidate cells, the method comprising the steps of: receiving PRACH measurements for the UE from the candidate cells; and selecting from the candidate cells one or more cells for the UE as its secondary serving cells based on the received PRACH measurements.

Claims

1. A method for performing a cell selection for a user equipment (UE) at a primary serving cell of the UE in a Coordinated Multi-Point (CoMP) cluster including the primary serving cell and one or more candidate cells, the method comprising:

receiving Physical Random Access Channel (PRACH) measurements for the UE from the candidate cells; and

selecting from the candidate cells one or more cells for the UE as its secondary serving cells based on the received PRACH measurements.

2. The method according to claim 1, wherein the PRACH measurements are strengths of a PRACH preamble signal from the UE, the strengths being obtained by the candidate cells.

3. The method according to claim 1, wherein the PRACH measurements are based on all PRACH preambles belonging to all cells in the CoMP cluster.

4. The method according to claim 1, further comprising:

detecting a PRACH preamble signal of the UE to obtain PRACH information of the UE; and

transmitting the PRACH information to the candidate cells for obtaining the PRACH measurements.

5. The method according to claim 4, wherein the PRACH information comprises at least one of the UE'"'"'s scrambling code, PRACH preamble sequence, PRACH timing, and direction of angle (DoA).

6. The method according to claim 4, wherein each of the PRACH measurements is based on the PRACH information and a PRACH preamble signal, which is previously received by a corresponding candidate cell from the UE.

7. The method according to claim 4, further comprising:

instructing each of the candidate cells to perform path searching for the UE based on the PRACH information.

8. The method according to claim 7, wherein the path searching is performed on antennas at each of the candidate cells to obtain path strengths as the PRACH measurements.

9. The method according to claim 1, wherein the candidate cells are neighbor cells to the primary serving cell within the CoMP cluster.

10. The method according to claim 1, wherein the candidate cells are all the cells in the CoMP cluster other than the primary serving cell.

11. The method according to claim 1, further comprising:

after receiving the PRACH measurements for the UE from the candidate cells, terminating the cell selection when all of the received PRACH measurements are lower than a first threshold.

12. The method according to claim 1, further comprising:

before receiving the PRACH measurements for the UE from the candidate cells, obtaining the primary serving cell'"'"'s PRACH measurement for the UE and comparing the obtained PRACH measurement with a second threshold.

13. The method according to claim 12, further comprising:

terminating the cell selection when the primary serving cell'"'"'s PRACH measurement for the UE is higher than the second threshold.

14. A computer-readable storage medium having computer-readable instructions to facilitate cell selection for a user equipment (UE) at a primary serving cell of the UE in a Coordinated Multi-Point (CoMP) cluster including the primary serving cell and one or more candidate cells, the instructions being executable by a computing device, the instructions comprising:

receiving Physical Random Access Channel (PRACH) measurements for the UE from the candidate cells; and

selecting from the candidate cells one or more cells for the UE as its secondary serving cells based on the received PRACH measurements.

15. An apparatus for performing a cell selection for a user equipment (UE at a primary serving cell of the UE in a Coordinated Multi-Point (CoMP) cluster including the primary serving cell and one or more candidate cells, the apparatus serving the primary serving cell and comprising:

a receiving unit configured to receive Physical Random Access Channel (PRACH) measurements for the UE from the candidate cells; and

a selecting unit configured to select from the candidate cells one or more cells for the UE as its secondary serving cells based on the received PRACH measurements.

16. The apparatus according to claim 15, wherein the PRACH measurements are strengths of a PRACH preamble signal from the UE, the strengths being obtained by the candidate cells.

17. The apparatus according to claim 15, wherein the PRACH measurements are based on all PRACH preambles belonging to all cells in the CoMP cluster.

18. The apparatus according to claim 15, further comprising:

a detecting unit configured to detect a PRACH preamble signal of the UE to obtain PRACH information of the UE; and

a transmitting unit configured to transmit the PRACH information to the candidate cells for obtaining the PRACH measurements.

19. The apparatus according to claim 18, wherein the PRACH information comprises at least one of the UE'"'"'s scrambling code, PRACH preamble sequence, PRACH timing, and direction of angle (DoA).

20. The apparatus according to claim 18, wherein each of the PRACH measurements is based on the PRACH information and a PRACH preamble signal, which is previously received by a corresponding candidate cell from the UE.

21. The apparatus according to claim 18, further comprising:

an instructing unit configured to instruct each of the candidate cells to perform path searching for the UE based on the PRACH information.

22. The apparatus according to claim 21, wherein the path searching is to be performed on antennas at each of the candidate cells to obtain path strengths as the PRACH measurements.

23. (canceled)

24. (canceled)

25. An apparatus for use in a cell selection for a user equipment (UE) at a primary serving cell of the UE in a Coordinated Multi-Point (CoMP) cluster including the primary serving cell and one or more candidate cells, the apparatus serving one of the candidate cells and comprising:

a Physical Random Access Channel (PRACH) measurement obtaining unit configured to obtain a PRACH measurement for the UE; and

a transmitting unit configured to transmit the PRACH measurement to the primary serving cell for use in the cell selection.

26. The apparatus according to claim 25, wherein the PRACH measurement obtaining unit is configured to obtain the PRACH measurement based on all PRACH preambles belonging to all cells in the CoMP cluster.

27. The apparatus according to claim 25, further comprising:

a receiving unit configured to receive a PRACH preamble signal from the UE and to receive PRACH information of the UE from the primary serving cell.

28. The apparatus according to claim 27, wherein the PRACH information comprises at least one of the UE'"'"'s scrambling code, PRACH preamble sequence, PRACH timing, and direction of angle (DoA).

29. The apparatus according to claim 27, wherein the PRACH measurement obtaining unit is configured to obtain the PRACH measurement based on the PRACH information and the PRACH preamble signal.

30. The apparatus according to claim 27, further comprising:

a path searching unit configured to perform path searching on an antenna the one of the candidate cells, which is served by the apparatus, based on the PRACH information to obtain a path strength as the PRACH measurement.