METHOD AND MTC DEVICE FOR PERFORMING RANDOM ACCESS PROCEDURE FOR COVERAGE ENHANCEMENT

• US 20160302080A1
• Filed: 12/01/2014
• Published: 10/13/2016
• Est. Priority Date: 12/05/2013
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: HWANG, Daesung, AHN, Joonkui, YANG, Suckchel, YI, Yunjung
• Granted Patent: US 10,306,482 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04J 11/0076 Acquisition of secondary synchronisation channel, e.g. detection of cell-ID group
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 1/189 Transmission or retransmission of more than one copy of a message
• CPC Class Codes: H04L 5/001 the frequencies being arranged in component carriers
• CPC Class Codes: H04L 69/28 Timers or timing mechanisms used in protocols
• CPC Class Codes: H04W 16/26 Cell enhancers or enhancement, e.g. for tunnels, building shadow
• CPC Class Codes: H04W 4/70 Services for machine-to-machine communication [M2M] or machine type communication [MTC]
• CPC Class Codes: H04W 72/0473 the resource being transmission power
• CPC Class Codes: H04W 72/21 in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 74/08 Non-scheduled access, e.g. ALOHA hybrid access H04W74/02
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access

Abstract

A disclosure of the present specification provides a method for performing a random access procedure for coverage enhancement. The method may comprise the steps of transmitting a random access preamble repetitively to a certain cell on the basis of a predetermined repetition level; when a random access response has not received within a random access response window, reconfiguring the repetition level; and retransmitting the random access preamble repetitively on the basis of the reconfigured repetition level.

Claims

1. A method of performing a random access procedure by a machine-type communication (MTC) device located in a coverage extension region, the method comprising:

generating a random access preamble to a specific cell; and

repeatedly transmitting the random access preamble according to a preset repetition level.

2. The method of claim 1, further comprising:

reconfiguring the repetition level when no random access response (RAR) is received within an RAR window; and

repeatedly retransmitting the random access preamble according to the reconfigured repetition level.

3. The method of claim 2, wherein the reconfiguring the repetition level reconfigures the repetition level based on a preset mode.

4. The method of claim 3, wherein the preset mode is a mode of reconfiguring the repetition level to a possible lowest repetition level or a repetition level selected based on a measurement by the MTC device.

5. The method of claim 3, wherein the preset mode is a mode of increasing the preset repetition level by one.

6. The method of claim 3, wherein the preset mode is a mode of increasing the preset repetition level by one when transmission power for the random access preamble reaches maximum transmission power configured in the MTC device or preamble transmission power at a time of performing power ramping is the maximum transmission power or greater.

7. The method of claim 3, when the preset mode is a mode of reconfiguring the repetition level based on total PRACH power, in which the total PRACH power is total power for subframes corresponding to the repeatedly transmitted random access preamble.

8. The method of claim 3, wherein the preset mode is a mode of reconfiguring the repetition level according to repetition level information comprised in a PDCCH order when the random access procedure starts according to the PDCCH order.

9. The method of claim 2, further comprising:

transmitting a scheduled message when an RAR is received;

reconfiguring the preset repetition level when no message 4 (Msg

     4) is received until a contention resolution timer expires; and

repeatedly retransmitting the random access preamble according to the reconfigured repetition level.

10. The method of claim 9, wherein the reconfiguring the preset repetition level reconfigures the preset repetition level based on an additional preset mode.

11. The method of claim 10, wherein the additional preset mode is a mode of maintaining the preset repetition level in a case where the received RAR comprises a backoff indicator, and increasing the preset repetition level in a case where the received RAR comprises no backoff indicator.

12. The method of claim 10, wherein the additional preset mode is a mode of configuring the preset repetition level to be a repetition level corresponding to the scheduled message, in which the repetition level corresponding to the scheduled message is one of a possible lowest repetition level, a repetition level selected based on a measurement by the MTC device, and a repetition level corresponding to a random access preamble successfully transmitted through retransmission before the scheduled message.

13. The method of claim 10, wherein the received RAR comprises a repetition level field, and the additional preset mode is a mode of reconfiguring the preset repetition level according to the repetition level field.

14. The method of claim 10, wherein the additional preset mode is a mode of selecting and performing one involving smaller total RACH power of power ramping and a change of the preset repetition level, in which the total PRACH power is total power for subframes corresponding to the repeatedly transmitted random access preamble.

15. A machine-type communication (MTC) device located in a coverage extension region to perform a random access procedure for coverage enhancement, the MTC device comprising:

a transceiver to repeatedly transmit a random access preamble to a specific cell according to a preset repetition level; and

a processor to reconfigure the repetition level when no random access response (RAR) is received within an RAR window and to control the transceiver to repeatedly retransmit the random access preamble according to the reconfigured repetition level.

16. The MTC device of claim 15, wherein the transceiver transmits a scheduled message when an RAR is received, and the processor reconfigures the preset repetition level when no message 4 (Msg 4) is received until a contention resolution timer expires, and controls the transceiver to repeatedly retransmit the random access preamble according to the reconfigured repetition level.