Dual link handover

Patent metadata

Field	Value
Publication number	US-10244444-B2
Application number	US-201615012062-A
Country	US
Kind code	B2
Filing date	Feb 1, 2016
Priority date	Mar 4, 2015
Publication date	Mar 26, 2019
Grant date	Mar 26, 2019

Abstract

Methods, systems, and devices for wireless communication are described. A user equipment (UE) may receive data from both a source base station and a target base station during handover. For example, the UE may refrain from resetting or reestablishing media access control (MAC) and packet data convergence protocol (PDCP) layer configurations until after a successful access procedure is performed with the target base station. In some cases, a single radio link control (RLC)/PDCP stack may be used during handover procedures. A source base station may, for example, forward data to a target base station after receiving a handover execution message. A UE may identify and resolve any duplicate data sent by both base stations during the transition. Additional signaling may be used (e.g., during the radio resource control (RRC) configuration) to indicate that a UE supports dual link handover.

First claim

What is claimed is:

1. A method of wireless communication, comprising:
receiving a first data transmission from a source base station while in a medium access control (MAC) configuration, a radio link control (RLC) configuration, and a packet data convergence protocol (PDCP) configuration;
receiving a connection reconfiguration message associated with a handover from the source base station to a target base station;
applying a radio resource control (RRC) configuration based at least in part on the received connection reconfiguration message;
receiving a second data transmission from the source base station after receiving the connection reconfiguration message;
performing an access procedure with the target base station based at least in part on receiving the connection reconfiguration message;
determining whether the access procedure was successful; and
resetting the MAC configuration, resetting the RLC configuration, or reestablishing the PDCP configuration, or any combination thereof, based at least in part on a determination that the access procedure was successful.

2. The method of claim 1 , further comprising:
transmitting an indication of a dual link handover capability to the source base station, wherein the second data transmission is received based at least in part on the indication.

3. The method of claim 2 , wherein the dual link handover capability is associated with a low latency capability.

4. The method of claim 1 , further comprising:
receiving a subsequent data transmission from the target base station based at least in part on the reset MAC configuration, the reset RLC configuration, the reestablished PDCP configuration, or any combination thereof.

5. The method of claim 4 , wherein the second data transmission and the subsequent data transmission use a same RLC/PDCP stack.

6. The method of claim 1 , further comprising:
receiving a third data transmission from the target base station prior to resetting the MAC configuration, resetting the RLC configuration, or reestablishing the PDCP configuration, or any combination thereof.

7. The method of claim 6 , wherein the third data transmission is a source base station ciphered transmission.

8. The method of claim 6 , wherein the third data transmission corresponds to a same logical channel as the second data transmission from the source base station.

9. The method of claim 1 , further comprising:
suppressing a radio link monitoring (RLM) procedure based at least in part on receiving the connection reconfiguration message.

10. The method of claim 9 , further comprising:
resuming the RLM procedure with the source base station based at least in part on determining that the access procedure was unsuccessful.

11. The method of claim 9 , further comprising:
resuming the RLM procedure with the target base station based at least in part on determining that the access procedure was successful.

12. The method of claim 1 , further comprising:
purging the connection reconfiguration message based at least in part on determining that the access procedure was unsuccessful; and
continuing communication with the source base station.

13. The method of claim 1 , wherein determining that the access procedure was successful comprises:
receiving a contention resolution message from the target base station.

14. A method of wireless communication at a target base station, comprising:
receiving, by the target base station, a handover prepare request from a source base station;
receiving an access request from a wireless device;
receiving a connection reconfiguration complete message from the wireless device based at least in part on the access request; and
transmitting a handover execution message to the source base station based at least in part on the connection reconfiguration complete message.

15. The method of claim 14 , further comprising:
receiving an indication of a dual link handover capability from the source base station, wherein a data transmission is sent based at least in part on the indication.

16. The method of claim 15 , wherein the dual link handover capability is associated with a low latency capability.

17. The method of claim 14 , further comprising:
receiving a sequence number (SN) status transfer message or a bearer data message from the source base station in response to the handover execution message.

18. The method of claim 17 , further comprising:
sending a data transmission to the wireless device based at least in part on receiving the SN status transfer message or the bearer data message.

19. The method of claim 14 , further comprising:
sending a source base station ciphered transmission to the wireless device prior to receiving the connection reconfiguration complete message.

20. An apparatus for wireless communication, comprising:
means for receiving a first data transmission from a source base station while in a medium access control (MAC) configuration, a radio link control (RLC) configuration, and a packet data convergence protocol (PDCP) configuration;
means for receiving a connection reconfiguration message associated with a handover from the source base station to a target base station;
means for applying a radio resource control (RRC) configuration based at least in part on the received connection reconfiguration message;
means for receiving a second data transmission from the source base station after receiving the connection reconfiguration message;
means for performing an access procedure with the target base station based at least in part on receiving the connection reconfiguration message;
means for determining whether the access procedure was successful; and
means for resetting the MAC configuration, resetting the RLC configuration, or reestablishing the PDCP configuration, or any combination thereof, based at least in part on a determination that the access procedure was successful.

21. The apparatus of claim 20 , further comprising:
means for transmitting an indication of a dual link handover capability to the source base station, wherein the second data transmission is received based at least in part on the indication.

22. The apparatus of claim 21 , wherein the dual link handover capability is associated with a low latency capability.

23. The apparatus of claim 20 , further comprising:
means for receiving a subsequent data transmission from the target base station based at least in part on the reset MAC configuration, the reset RLC configuration, the reestablished PDCP configuration, or any combination thereof.

24. An apparatus for wireless communication at a target base station, comprising:
means for receiving, by the target base station, a handover prepare request from a source base station;
means for receiving an access request from a wireless device;
means for receiving a connection reconfiguration complete message from the wireless device based at least in part on the access request; and
means for transmitting a handover execution message to the source base station based at least in part on the connection reconfiguration complete message.

25. The apparatus of claim 24 , further comprising:
means for transmitting an indication of a handover capability to the source base station.

26. The apparatus of claim 24 , further comprising:
means for receiving an indication of a dual link handover capability from the source base station.

Assignees

• Qualcomm Inc

Inventors

• Ozturk Ozcan
• Wang Jun
• Patwardhan Ravindra Manohar
• Khobare Abhijit
• Gupta Ajay
• Vajapeyam Madhavan Srinivasan

Classifications

• H04W36/026 Primary

  Multicasting of data during hand-off · CPC title

• H04W76/20

  Manipulation of established connections · CPC title

• H04W76/30

  Connection release · CPC title

• H04W74/0833

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

• H04W36/08 Primary

  Reselecting an access point · CPC title