Method and MTC device for performing random access procedure for coverage enhancement

• US 10,306,482 B2
• Filed: 12/01/2014
• Issued: 05/28/2019
• 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
• Primary Examiner(s): Yao, Kwang B
• Assistant Examiner(s): Loo, Juvena W
• Application Number:
  US15/038,528
• Publication Number:
  US 20160302080A1
• Time in Patent Office: 1,639 Days
• Field of Search: None
• 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, the method performed by a wireless device located in a coverage extension region of a long term evolution (LTE) based cell and comprising:

repeatedly transmitting a random access preamble according to a first repetition level to a cell;

if a random access response (RAR) including a random access preamble identifier corresponding to the transmitted random access preamble is not received from the cell, performing a repetition level change from the first repetition level to a second repetition level and performing a power ramping;

repeatedly retransmitting the random access preamble according to the second repetition level,

wherein the random access preamble is repeatedly transmitted and retransmitted on a plurality of subframes, and

wherein the repetition level change is performed firstly and then the power ramping is performed, such that the power ramping is performed if the RAR including the random access preamble identifier is not received and if the retransmission based on the repetition level change is performed;

transmitting a scheduled message when the RAR is received; and

if a message in response to the scheduled message is not received until a contention resolution timer expires, repeatedly retransmitting the random access preamble.

2. The method of claim 1, wherein the second repetition level is higher than the first repetition level by one, and

wherein information on the first and second the repetition levels is received via a higher layer signal.

3. The method of claim 1, wherein the power ramping is performed until reaching a maximum transmission power configured in the wireless device.

4. The method of claim 1, wherein the repetition level change is performed based on total physical random access channel (PRACH) power, and

wherein the total PRACH power corresponds to a summation of power on subframes where the random access preamble is repeatedly transmitted.

5. The method of claim 1, wherein the first repetition level change from the first repetition level to the second repetition level is performed based on an additional preset mode.

6. The method of claim 5, wherein the additional preset mode is one of a first mode of maintaining the first repetition level when the RAR comprises a backoff indicator, and a second mode of performing the change from the first repetition level to the second repetition level when the RAR comprises no backoff indicator.

7. The method of claim 1, wherein the RAR is repeatedly transmitted from the cell.

8. The method of claim 1, wherein if the random access preamble is transmitted by a physical downlink control channel (PDCCH) order, the PDCCH order includes information regarding the first repetition level.

9. A wireless device located in a coverage extension region of a long term evolution (LTE) based cell to perform a random access procedure for coverage enhancement, the wireless device comprising:

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

a processor to;

perform a repetition level change from the first repetition level to a second repetition level and perform a power ramping, if a random access response (RAR) including a random access preamble identifier corresponding to the transmitted random access preamble is not received from the cell,

control the transceiver to repeatedly retransmit the random access preamble according to the second repetition level,

wherein the random access preamble is repeatedly transmitted and retransmitted on a plurality of subframes, and

wherein the repetition level change is performed firstly and then the power ramping is performed, such that the power ramping is performed if the RAR including the random access preamble identifier is not received and if the retransmission based on the repetition level change is performed,

control the transceiver to transmit a scheduled message when the RAR is received, and

if a message in response to the scheduled message is not received until a contention resolution timer expires, control the transceiver to repeatedly retransmit the random access preamble.

10. The wireless device of claim 9, wherein the second repetition level is higher than the first repetition level by one, and

wherein information on the first and second the repetition levels is received via a higher layer signal.

11. The wireless device of claim 9, wherein the RAR is repeatedly transmitted from the cell.

12. The wireless device of claim 9, wherein if the random access preamble is transmitted by a physical downlink control channel (PDCCH) order, the PDCCH order includes information regarding the first repetition level.