RRC State Transition Techniques with Reduced Signaling Overhead

• US 20170094711A1
• Filed: 09/30/2015
• Published: 03/30/2017
• Est. Priority Date: 09/30/2015
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Hu, Haijing, Liang, Huarui, Zhang, Dawei
• Granted Patent: US 10,009,942 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04W 36/0055 Transmission or use of information for re-establishing the radio link
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access
• CPC Class Codes: H04W 76/19 Connection re-establishment
• CPC Class Codes: H04W 76/27 Transitions between radio resource control [RRC] states
• CPC Class Codes: H04W 76/38 triggered by timers
• CPC Class Codes: H04W 88/02 Terminal devices
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

This disclosure relates to techniques for establishing radio resource control connections between wireless devices and cellular networks. According to some embodiments, a wireless device and a cellular base station may establish a radio resource control (RRC) connection. The wireless device may indicate to the cellular base station to store access stratum context information associated with the wireless device after the RRC connection is released. The wireless device may also store access stratum context information associated with the cellular base station. The stored access stratum context information may be used in conjunction with a subsequent RRC connection establishment procedure between the wireless device and the cellular base station.

Claims

1. An apparatus, comprising:

a processing element configured to;

establish a first radio resource control (RRC) connection with a cellular base station;

communicate data with the cellular base station using the first RRC connection;

release the first RRC connection with the cellular base station, wherein access stratum context information for the first RRC connection with the cellular base station is stored after releasing the first RRC connection; and

establish a second RRC connection with the cellular base station using the stored access stratum context information.

2. The apparatus of claim 1, wherein to establish the first RRC connection, the processing element is further configured to:

provide an indication to store access stratum context information for the first RRC connection after the first RRC connection is released to the cellular base station, wherein the indication causes the cellular base station to store access stratum context information for the first RRC connection after the first RRC connection is released.

3. The apparatus of claim 2,

wherein the indication further causes one or more additional cellular network entities to store access stratum context information for the first RRC connection after the first RRC connection is released.

4. The apparatus of claim 1, wherein to establish the first RRC connection, the processing element is further configured to:

provide a physical random access channel preamble to the cellular base station;

receive a random access response from the cellular base station;

provide a RRC connection request message to the cellular base station, wherein the RRC connection request message comprises an indication that the RRC connection is for frequent small data exchanges; and

receive a contention resolution message.

5. The apparatus of claim 1, wherein to establish the first RRC connection, the processing element is further configured to:

provide a physical random access channel (PRACH) preamble to the cellular base station, wherein the PRACH preamble is selected to indicate that the RRC connection is for frequent small data exchanges;

receive a random access response from the cellular base station;

provide a RRC connection request message to the cellular base station; and

receive a contention resolution message.

6. The apparatus of claim 1, wherein the access stratum context information comprises one or more of:

Uu context information;

security information;

data radio bearer information.

7. A wireless user equipment (UE) device, comprising:

an antenna;

a radio, operatively coupled to the antenna; and

a processing element, operatively coupled to the radio;

wherein the UE device is configured to;

indicate to a cellular network to store access stratum context information associated with a radio resource control (RRC) connection with a cellular base station;

store access stratum context information associated with the RRC connection with the cellular base station; and

utilize stored access stratum context information when establishing a subsequent RRC connection with the cellular base station.

8. The UE device of claim 7, wherein the UE device is further configured to indicate to the cellular network to store the access stratum context information by way of one or more of:

inclusion of a specific cause value in an RRC connection request;

or

use of a specific physical random access channel preamble value.

9. The UE device of claim 7,

wherein utilizing the stored access stratum context information when establishing the subsequent RRC connection with the cellular base station reduces signaling overhead associated with establishing the subsequent RRC connection.

10. The UE device of claim 7,

wherein RRC connection establishment security procedures when establishing the subsequent RRC connection with the cellular base station are avoided by utilizing the stored access stratum context information.

11. The UE device of claim 7, wherein the UE device is further configured to:

determine that the stored access stratum context information has expired; and

discard the stored access stratum context information.

12. A cellular base station, comprising:

an antenna;

a radio, operatively coupled to the antenna; and

a processing element, operatively coupled to the radio;

wherein the cellular base station is configured to;

receive a request to establish a first RRC connection from a wireless user equipment (UE) device, wherein the request to establish the first RRC connection comprises an indication to store access stratum context information associated with the UE device; and

store access stratum context information associated with the UE device after the first RRC connection with the UE device is released based at least in part on the indication to store access stratum context information associated with the UE device.

13. The cellular base station of claim 12, wherein the cellular base station is further configured to:

receive a request to establish a second RRC connection from the UE device;

determine that access stratum context information associated with the UE device is stored by the cellular base station; and

utilize the stored access stratum context information associated with the UE device to establish the second RRC connection.

14. The cellular base station of claim 13,

wherein by utilizing the stored access stratum context information associated with the UE device to establish the second RRC connection, a RRC connection establishment procedure to establish the second RRC connection is simplified relative to a RRC connection establishment procedure to establish the first RRC connection.

15. The cellular base station of claim 12, wherein the cellular base station is further configured to:

provide an indication to store access stratum context information associated with the UE device to one or more other cellular network entities based at least in part on the indication received from the UE device.

16. The cellular base station of claim 12, wherein the stored access stratum context information comprises one or more of:

Uu context information for the UE device;

security information for the UE device;

data radio bearer information for the UE device;

S1-MME context information for the UE device;

or

S1-U bearer information for the UE device.

17. The cellular base station of claim 12,

wherein the indication to store access stratum context information associated with the UE device comprises inclusion of a cause value indicating that the UE device performs frequent small transmissions in a RRC connection request message received from the UE device.

18. The cellular base station of claim 12,

wherein the indication to store access stratum context information associated with the UE device comprises use of a physical random access channel (PRACH) preamble defined as indicating that the UE device performs frequent small transmissions.

19. The cellular base station of claim 12, wherein the cellular base station is further configured to:

initiate a timer associated with the stored access stratum context information associated with the UE device; and

discard the stored access stratum context information associated with the UE device if the timer expires.

20. The cellular base station of claim 19, wherein the cellular base station is further configured to:

reset the timer based on each new RRC connection between the UE device and the cellular base station.