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

• US 10,623,967 B2
• Filed: 04/10/2019
• Issued: 04/14/2020
• 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:
  US16/380,541
• Publication Number:
  US 20190239087A1
• Time in Patent Office: 370 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;

based on that no random access response (RAR) including a random access preamble identifier corresponding to the transmitted random access preamble is received within a RAR window from the cell, performing a repetition level change from the first repetition level to a second repetition level and a power ramping,

wherein the repetition level change is performed firstly and then the power ramping is performed; and

repeatedly retransmitting the random access preamble based on the repetition level change to the second repetition level and based on the power ramping,

wherein based on that the random access preamble is transmitted according to a physical downlink control channel (PDCCH) order, the PDCCH order includes repetition level information.

2. The method of claim 1, wherein the random access preamble is repeatedly transmitted and retransmitted on a plurality of subframes.

3. The method of claim 1, further comprising:

transmitting a scheduled message when the RAR is received; and

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

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

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

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

6. The method of claim 1, wherein the change of the repetition level is performed based on a total PRACH power, and

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

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

8. A wireless device located in a coverage extension region to perform a random access procedure for coverage enhancement of a long term evolution (LTE) based cell, 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 a power ramping, based on that no random access response (RAR) including a random access preamble identifier corresponding to the transmitted random access preamble is received within a RAR window from the cell,

wherein the repetition level change is performed firstly and then the power ramping is performed,

wherein the processor repeatedly retransmits the random access preamble based on the repetition level change to the second repetition level and based on the power ramping, and

wherein based on that the random access preamble is transmitted according to a physical downlink control channel (PDCCH) order, the PDCCH order includes repetition level information.

9. The wireless device of claim 8, wherein the random access preamble is repeatedly transmitted and retransmitted on a plurality of subframes.

10. The wireless device of claim 8, wherein the processor transmits a scheduled message when the RAR is received;

and

wherein based on that a message in response to the scheduled message is not received until a contention resolution timer expires, the processor repeatedly retransmits the random access preamble.

11. The wireless device of claim 8, wherein the second repetition level is higher than the first repetition level, and

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

12. The wireless device of claim 8, wherein the power ramping is performed until reaching a maximum transmission power configured in the wireless device.

13. The wireless device of claim 8, wherein the change of the repetition level is performed based on a total PRACH power, and

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