Cell search method and terminal device

• US 10,952,136 B2
• Filed: 05/19/2020
• Issued: 03/16/2021
• Est. Priority Date: 01/29/2018
• Status: Active Grant

• Current Assignee: Guangdong OPPO Mobile Telecommunications Corporation Limited
• Original Assignee: Guangdong OPPO Mobile Telecommunications Corporation Limited
• Inventors: Tang, Hai
• Primary Examiner(s): Nguyen, Lee
• Application Number:
  US16/878,216
• Publication Number:
  US 20200280916A1
• Time in Patent Office: 301 Days
• Field of Search: 4554352, 455515
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 52/0212 managed by the network, e.g. network or access point is master and terminal is slave
• CPC Class Codes: H04W 60/02 by periodical registration
• CPC Class Codes: H04W 76/27 Transitions between radio resource control [RRC] states
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Provided are a cell search method and a terminal device. The method is applied to a terminal device in an inactive state, wherein the inactive state indicates that the terminal device is disconnected from a network device, and the network device and the terminal device both retain contextual information of the terminal device, the contextual information being used for establishing a connection between the terminal device and the network device. The method comprises: when no suitable cell is found for camping, a terminal device entering an arbitrary cell search state to search for an acceptable cell and/or a suitable cell. In the implementations of the present disclosure, when no suitable cell is found for camping, a terminal device in an inactive state searches for an acceptable cell and/or a suitable cell by means of entering an arbitrary cell search state.

Claims

1. A cell search method, comprising:

searching, by a terminal device, a cell to reside, wherein the terminal device is in an inactive state, wherein the inactive state refers to that the terminal device is disconnected from a network device, and both the network device and the terminal device retain context information of the terminal device, wherein the context information is used for establishing a connection between the terminal device and the network device;

entering, by the terminal device, an arbitrary cell search state to search for an acceptable cell and/or a suitable cell when the terminal device does not find any suitable cell to reside in, wherein the acceptable cell is a cell in which the terminal device is capable of residing and only obtaining a restricted service, and the suitable cell is a cell in which the terminal device is capable of residing and obtaining a normal service; and

continuing to maintain, by the terminal device, the inactive state and a second timer when entering the arbitrary cell search state, wherein the second timer comprises a location update timer.

2. The method of claim 1, further comprising:

when the acceptable cell is found, residing, by the terminal device, in the acceptable cell, and continuing to search for the suitable cell.

3. The method of claim 2, further comprising:

when entering the arbitrary cell search state, starting, by the terminal device, a first timer;

when no suitable cell is found before the first timer expires, entering, by the terminal device, an idle state and deleting the context information;

or

when the suitable cell is found before the first timer expires, stopping, by the terminal device, the first timer and residing in the suitable cell.

4. The method of claim 2, further comprising:

when entering the arbitrary cell search state, entering, by the terminal device, an idle state and deleting the context information.

5. The method of claim 2, further comprising:

when entering the arbitrary cell search state, continuing to maintain, by the terminal device, the inactive state and a second timer, wherein the second timer comprises a location update timer.

6. The method of claim 1, further comprising:

when entering the arbitrary cell search state, starting, by the terminal device, a first timer;

when no suitable cell is found before the first timer expires, entering, by the terminal device, an idle state and deleting the context information;

or,

when the suitable cell is found before the first timer expires, stopping, by the terminal device, the first timer and residing in the suitable cell.

7. The method of claim 6, further comprising:

before starting the first timer, receiving, by the terminal device, configuration information sent by the network device, wherein the configuration information is used for the terminal device to configure the first timer.

8. The method of claim 7, wherein the configuration information is information configured for the terminal device when the network device instructs the terminal device to enter the inactive state.

9. The method of claim 8, further comprising:

after entering the idle state and deleting the context information, continuing to maintain, by the terminal device, the arbitrary cell search state.

10. The method of claim 7, further comprising:

after entering the idle state and deleting the context information, continuing to maintain, by the terminal device, the arbitrary cell search state.

11. The method of claim 6, further comprising:

after entering the idle state and deleting the context information, continuing to maintain, by the terminal device, the arbitrary cell search state.

12. The method of claim 1, further comprising:

when entering the arbitrary cell search state, entering, by the terminal device, an idle state and deleting the context information.

13. The method of claim 12, further comprising:

after entering the idle state and deleting the context information, continuing to maintain, by the terminal device, the arbitrary cell search state.

14. The method of claim 1, further comprising:

when the second timer expires, entering, by the terminal device, an idle state and deleting the context information.

15. A terminal device, comprising a processor, wherein

the processor is configured to search a cell to reside, wherein the terminal device is in an inactive state, wherein the inactive state refers to that the terminal device is disconnected from a network device, and both the network device and the terminal device retain context information of the terminal device, wherein the context information is used for establishing a connection between the terminal device and the network device;

enter an arbitrary cell search state to search for an acceptable cell and/or a suitable cell when the terminal device does not find any suitable cell to reside in, wherein the acceptable cell is a cell in which the terminal device is capable of residing and only obtaining a restricted service, and the suitable cell is a cell in which the terminal device is capable of residing and obtaining a normal service; and

continue to maintain the inactive state and a second timer when entering the arbitrary cell search state, wherein the second timer comprises a location update timer.

16. The terminal device of claim 15, wherein the processor is further configured to, when the acceptable cell is found, reside in the acceptable cell, and continue to search for the suitable cell.

17. The terminal device of claim 16, wherein the processor is further configured to:

start a first timer when the terminal device enters the arbitrary cell search state;

when no suitable cell is found before the first timer expires, enter an idle state and delete the context information;

or

when the suitable cell is found before the first timer expires, stop the first timer and reside in the suitable cell.

18. The terminal device of claim 16, wherein the processor is further configured to:

when the terminal device enters the arbitrary cell search state, enter an idle state and delete the context information.

19. The terminal device of claim 16, wherein the processor is further configured to:

when the terminal device enters the arbitrary cell search state, continue to maintain the inactive state and a second timer, wherein the second timer comprises a location update timer.

20. The terminal device of claim 15, wherein the processor is further configured to:

start a first timer when the terminal device enters the arbitrary cell search state;

when no suitable cell is found before the first timer expires, enter an idle state and delete the context information;

or

when the suitable cell is found before the first timer expires, stop the first timer and reside in the suitable cell.

21. The terminal device of claim 20, further comprising a transceiver, wherein

the transceiver is configured to receive configuration information sent by the network device before the processor starts the first timer, wherein the configuration information is used for the terminal device to configure the first timer.

22. The terminal device of claim 21, wherein the configuration information is information configured for the terminal device when the network device instructs the terminal device to enter the inactive state.

23. The terminal device of claim 22, wherein the processor is further configured to:

after the terminal device enters the idle state and deletes the context information, continue to maintain the arbitrary cell search state.

24. The terminal device of claim 21, wherein the processor is further configured to:

after the terminal device enters the idle state and deletes the context information, continue to maintain the arbitrary cell search state.

25. The terminal device of claim 15, wherein the processor is further configured to:

when the terminal device enters the arbitrary cell search state, enter an idle state and delete the context information.

26. The terminal device of claim 20, wherein the processor is further configured to:

after the terminal device enters the idle state and deletes the context information, continue to maintain the arbitrary cell search state.

27. The terminal device of claim 25, wherein the processor is further configured to:

after the terminal device enters the idle state and deletes the context information, continue to maintain the arbitrary cell search state.

28. The terminal device of claim 15, wherein the processor is further configured to:

when the second timer expires, enter an idle state and delete the context information.