METHOD IN WHICH USER EQUIPMENT PERFORMS RANDOM ACCESS IN A CARRIER AGGREGATION MOBILE COMMUNICATION SYSTEM

• US 20120076126A1
• Filed: 06/07/2010
• Published: 03/29/2012
• Est. Priority Date: 06/07/2009
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Yi, Seung June, Chun, Sung Duck, Jung, Sung Hoon, Lee, Young Dae, Park, Sung Jun
• Granted Patent: US 8,774,112 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04L 5/001 the frequencies being arranged in component carriers
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04W 74/085 collision avoidance

Abstract

The present document relates to a method in which user equipment carries out a process for random access to a base station in a carrier aggregation mobile communication system which performs communications using a plurality of component carriers (CCs), and to a terminal device for the method. The user equipment separately manages back-off operations for each of the CCs, and performs a random access preamble transmission using the relevant CC if another usable CC exists, even when a back-off period is being applied to a specific CC, to carry out a random access process in an efficient manner in a carrier aggregation mobile communication system.

Claims

1. A method for performing a random access procedure to an eNB at a User Equipment (UE) in a mobile communication system using carrier aggregation in which communication is performed using a plurality of component carriers, the method comprising:

transmitting a first random access preamble to the eNB through a first uplink component carrier (hereinafter referred to as ‘

UL CC’

) from among a plurality of UL CCs;

receiving a first random access response message including a backoff indicator as a response to the first random access preamble through a first downlink component carrier (hereinafter referred to as ‘

DL CC’

) corresponding to the first UL CC;

applying a backoff period to the first UL CC in consideration of the backoff indicator received through the first random access response message; and

transmitting a second random access preamble to the eNB through a second UL CC to which a backoff period is not applied from among the plurality of UL CCs even during the backoff period of the first UL CC.

2. The method according to claim 1, wherein the UE independently administrates backoff operations for the plurality of UL CCs when performing the random access procedure to the eNB.

3. The method according to claim 2, further comprising acquiring information about the plurality of UL CCs applicable for the random access procedure to the eNB and information about a plurality of DL CCs respectively corresponding to the plurality of UL CCs.

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

receiving a second random access response message including a backoff indicator as a response to the second random access preamble through a second DL CC corresponding to the second UL CC;

applying a backoff period to the second UL CC in consideration of the backoff indicator received through the second random access response message; and

transmitting a third random access preamble to the eNB through a UL CC corresponding to a backoff period which is ended first from among the plurality of UL CCs when backoff periods are applied to all the plurality of UL CCs.

5. A method according to claim 1, wherein the UE is configured to transmit a random access preamble only through one of the plurality of UL CCs at a specific time and receive a random access response message only through a DL CC corresponding to the one UL CC at a specific time.

6. A user equipment (UE) performing a random access procedure to an eNB in a mobile communication system using carrier aggregation in which communication is performed using a plurality of component carriers, the UE comprising:

a MAC layer module including a plurality of HARQ entities respectively corresponding to the plurality of component carriers, and controlling signal transmission using a plurality of uplink component carriers (referred to as ‘

UL CCs’

) and signal reception using a plurality of downlink component carriers (referred to as ‘

DL CCs’

) respectively corresponding to the plurality of UL CCs through the plurality of entities; and

a processor functionally connected with the MAC layer module and including a physical layer module performing signal transmission through the plurality of UL CCs and signal reception through the plurality of DL CCs,

wherein when a second UL CC to which a backoff period is not applied from among the plurality of UL CCs is present even during a backoff period for a first UL CC, the processor is configured to transmit a random access preamble to the eNB through the second UL CC.

7. The UE according to claim 6, wherein the processor independently manages backoff operations for the plurality of UL CCs when performing the random access procedure to the eNB.

8. The UE according to claim 7, wherein the processor stores information about the plurality of UL CCs applicable to the random access procedure to the eNB and information about the plurality of DL CCs respectively corresponding to the plurality of UL CCs.

9. The UE according to claim 6, wherein the processor is configured to transmit a random access preamble to the eNB through a UL CC corresponding to a backoff period which is ended first from among the plurality of UL CCs when backoff periods are applied to all the plurality of UL CCs.

10. The UE according to claim 6, wherein the processor is configured to transmit a random access preamble only through one of the plurality of UL CCs at a specific time and receive a random access response message only through a DL CC corresponding to the one UL CC at a specific time.