METHOD AND TERMINAL FOR RANDOM ACCESS TO SMALL CELL

• US 20150181624A1
• Filed: 06/12/2013
• Published: 06/25/2015
• Est. Priority Date: 06/27/2012
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Hwang, Daesung, Kim, Hakseong, Yang, Suckchel, Lee, Seungmin, You, Hyangsun, Yi, Yunjung, Seo, Dongyoun, Seo, Hanbyul
• Granted Patent: US 9,462,612 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04W 36/0005 Control or signalling for completing the hand-off
• CPC Class Codes: H04W 36/0077 of access information of target access point
• CPC Class Codes: H04W 74/002 Transmission of channel access control information
• CPC Class Codes: H04W 74/0841 with collision treatment

Abstract

The present invention relates to a method for random access to a small cell by means of a terminal. The method can include the steps of: receiving a plurality of settings for a random access preamble; selecting one of the plurality of settings; and transmitting the random access preamble according to the one selected setting. Here, a resource on which the random access preamble can be transmitted can be provided in plurality in one subframe, and the preamble transmitted on each resource is distinguishable.

Claims

1. A method for performing random access by a user equipment for a small cell, the method comprising:

receiving a plurality of configurations for a random access preamble;

selecting one of the plurality of configurations; and

transmitting the random access preamble according to a selected configuration,

wherein the random access preamble is transmitted on at least one resource in a subframe including plural resources on which the random access preamble is capable of being transmitted, and wherein a preamble transmitted on each resource is uniquely distinguishable.

2. The method of claim 1, wherein locations of the plurality of resources are aligned with a boundary of the subframe.

3. The method of claim 1, wherein locations of the plurality of resources are aligned with a boundary of each slot in the subframe.

4. The method of claim 1, wherein locations of the plurality of resources are aligned with a boundary of a group of OFDMA or SC-FDMA symbols.

5. The method of claim 1 further comprising

receiving a random access response including RA-RNTI,

wherein the RA-RNTI is calculated by a location index of the resource within a subframe index on which the preamble is transmitted and the subframe.

6. The method of claim 4, wherein a length of the random access preamble transmitted on the resource is shorter than a length of 3 OFDMA or SC-FDMA symbols in case of normal CP, and is shorter than a length of 2 OFDMA or SC-FDMA symbols in case of extended CP.

7. The method of claim 1, wherein the plurality of configurations are received through system information.

8. The method of claim 1, wherein the plurality of configurations include a configuration of format 0 to 4 for PRACH preamble and a configuration of new format which is different from the format 0 to 4.

9. The method of claim 8, wherein the new format is generated based on format 4 for PRACH preamble.

10. The method of claim 8, when in the selection step, the user equipment preferentially selects configuration of new format.

11. The method of claim 1, wherein the subframe is downlink subframe.

12. The method of claim 1, wherein the small cell is pico cell, femto cell, Home (e)NodeB or CSG cell.

13. A user equipment (UE) for performing random access for a small cell, the UE comprising:

a radio frequency (RF) unit configured to receive a plurality of configurations for random access preamble; and

a processor configured to control the RF unit, to select one of the plurality of configurations and to transmit the random access preamble according to the selected configuration,

wherein the random access preamble is transmitted on at least one resource in a subframe including plural resources on which the random access preamble is capable of being transmitted, and wherein a preamble transmitted on each resource is uniquely distinguishable.

14. The UE of claim 13, wherein locations of the plurality of resources are aligned with a boundary of the subframe.

15. The UE of claim 13, wherein locations of the plurality of resources are aligned with a boundary of each slot in the subframe.

16. The UE of claim 13, wherein locations of the plurality of resources are aligned with a boundary of a group of OFDMA or SC-FDMA symbols.