Random access method and apparatus

Patent metadata

Field	Value
Publication number	US-10999875-B2
Application number	US-201716608508-A
Country	US
Kind code	B2
Filing date	May 31, 2017
Priority date	Apr 25, 2017
Publication date	May 4, 2021
Grant date	May 4, 2021

Abstract

A random access method and an apparatus include performing listen before talk (LBT) on a first carrier, detecting a first signal on the first carrier when the terminal determines, through the LBT, that the first carrier is in a busy state, where the first carrier includes an unlicensed carrier, the first signal includes a first preamble signal or indication information, and the indication information indicates that the first carrier sends the first preamble signal, and sending a second preamble signal on the first carrier to attempt to access a base station when the terminal detects the first preamble signal or the indication information.

First claim

What is claimed is:

1. A random access method, implemented by a terminal, comprising:
performing listen before talk (LBT) on a first carrier, wherein the first carrier comprises an unlicensed carrier;
determining, through the LBT, that the first carrier is in a busy state;
detecting, in response to the first carrier being in the busy state, a first signal on the first carrier, wherein the first signal comprises a first preamble signal or indication information, and wherein the indication information indicates that the first carrier is for sending the first preamble signal; and
sending, in response to the detecting, a second preamble signal on the first carrier.

2. The random access method of claim 1 , wherein before performing the LBT, the random access method further comprises receiving a Radio Resource Control (RRC) configuration message from a base station, and wherein when the first carrier is in the busy state, the RRC configuration message instructs the terminal to either:
detect the first preamble signal; or
detect the indication information.

3. The random access method of claim 1 , further comprising receiving, on a second carrier, a random access response (RAR) message from a base station, wherein the second carrier comprises a licensed carrier.

4. The random access method of claim 3 , wherein before receiving the RAR message, the random access method further comprises receiving a system broadcast message from the base station, wherein the system broadcast message instructs the terminal to add a predetermined time offset before an RAR time window to receive the RAR message when the RAR time window arrives.

5. The random access method of claim 1 , further comprising sending a message to a base station using a third carrier, wherein the third carrier comprises a carrier of a cell in a time advanced group (TAG) of the base station.

6. The random access method of claim 4 , further comprising receiving, using the first carrier, a message from the base station after a window of a contention resolution timer is prolonged by a preset time period, wherein the preset time period is based on a detection time of the LBT or a forwarding time of the RAR message, and wherein the forwarding time of the RAR message indicates a duration of forwarding the RAR message from the first carrier to the second carrier.

7. A computer program product comprising computer-executable instructions for storage on a non-transitory computer-readable medium that, when executed by a processor, cause a terminal to:
perform listen before talk (LBT) on a first carrier, wherein the first carrier comprises an unlicensed carrier;
determine, through the LBT, that the first carrier is in a busy state;
detect, in response to the first carrier being in a busy state, a first signal on the first carrier, wherein the first signal comprises a first preamble signal or indication information, and wherein the indication information indicates that the first carrier sends the first preamble signal; and
send a second preamble signal on the first carrier.

8. The computer program product of claim 7 , wherein the computer-executable instructions further cause the terminal to receive a radio resource control (RRC) configuration message from a base station, and wherein when the first carrier is in the busy state, the RRC configuration message instructs the terminal to either:
detect the first preamble signal; or
detect the indication information.

9. The computer program product of claim 7 , wherein the computer-executable instructions further cause the terminal to receive, on a second carrier, a random access response (RAR) message from a base station, and wherein the second carrier comprises a licensed carrier.

10. The computer program product of claim 9 , wherein the computer-executable instructions further cause the terminal to receive a system broadcast message from the base station, wherein the system broadcast message causes the terminal to add a predetermined time offset before an RAR time window to receive the RAR message when the RAR time window arrives.

11. The computer program product of claim 7 , wherein the computer-executable instructions further cause the terminal to send a message to a base station using a third carrier, and wherein the third carrier comprises a carrier of a cell in a time advanced group (TAG) of the base station.

12. The computer program product of claim 10 , wherein the computer-executable instructions further cause the terminal to receive a message from the base station using the first carrier after a window of a contention resolution timer is prolonged by a preset time period, wherein the preset time period is based on a detection time of the LBT or a forwarding time of the RAR message, and wherein the forwarding time of the RAR message indicates a duration of forwarding the RAR message from the first carrier to the second carrier.

13. A terminal, comprising:
a bus;
a transceiver coupled to the bus and configured to perform listen before talk (LBT) on a first carrier, wherein the first carrier comprises an unlicensed carrier; and
a processor coupled to the bus and configured to:
determine, through the LBT, that the first carrier is in a busy state;
detect, in response to the first carrier being in a busy state, a first signal on the first carrier, wherein the first signal comprises a first preamble signal or indication information, and wherein the indication information indicates that the first carrier sends the first preamble signal; and

send a second preamble signal on the first carrier.

14. The terminal of claim 13 , wherein the transceiver is further configured to receive a radio resource control (RRC) configuration message from a base station, and wherein when the first carrier is in the busy state, the RRC configuration message instructs the terminal to either:
detect the first preamble signal; or
detect the indication information.

15. The terminal of claim 13 , wherein the transceiver is further configured to receive, on a second carrier, a random access response (RAR) message from a base station, and wherein the second carrier comprises a licensed carrier.

16. The terminal of claim 15 , wherein the transceiver is further configured to receive a system broadcast message from the base station, and wherein the system broadcast message causes the terminal to add a predetermined time offset before an RAR time window to receive the RAR message when the RAR time window arrives.

17. The terminal of claim 13 , wherein the transceiver is further configured to send a message to a base station using a third carrier, and wherein the third carrier comprises a carrier of a cell in a time advanced group (TAG) of the base station.

18. The terminal of claim 16 , wherein the transceiver is further configured to receive a message from the base station using the first carrier after a window of a contention resolution timer is prolonged by a preset time period, wherein the preset time period is based on a detection time of the LBT or a forwarding time of the RAR message, and wherein the forwarding time of the RAR message indicates a duration of forwarding the RAR message from the first carrier to the second carrier.

19. The terminal of claim 14 , wherein the transceiver is further configured to receive a system broadcast message from the base station, wherein the system broadcast message causes the terminal to add a predetermined time offset before a random access response (RAR) time window to receive an RAR message when the RAR time window arrives.

Assignees

• Huawei Tech Co Ltd

Inventors

• Li Xiaocui
• Li Guorong
• Xu Kai
• Zhang Lili

Classifications

• H04W76/27 Primary

  Transitions between radio resource control [RRC] states · CPC title

• H04W74/0833 Primary

  Random access procedures, e.g. with 4-step access · CPC title

• H04W74/0808 Primary

  using carrier sensing, e.g. carrier sense multiple access [CSMA] · CPC title

• H04W74/08

  Non-scheduled access, e.g. ALOHA (hybrid access H04W74/02) · CPC title

• H04W74/0841

  with collision treatment · CPC title