Method of enhanced connection recovery and loss-less data recovery

• US 9,504,082 B2
• Filed: 05/12/2015
• Issued: 11/22/2016
• Est. Priority Date: 01/18/2012
• Status: Active Grant

• Current Assignee: HFI Innovation, Inc. (MediaTek, Inc.)
• Original Assignee: MediaTek, Inc.
• Inventors: Johansson, Per Johan Mikael, Chen, Yih-Shen, Low, Tze-Ping, Plumb, William
• Primary Examiner(s): Louis, Vincelas
• Application Number:
  US14/709,479
• Publication Number:
  US 20150245405A1
• Time in Patent Office: 560 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H04W 36/0033 with transfer of context information
• CPC Class Codes: H04W 36/0061 of neighbour cell information
• CPC Class Codes: H04W 36/0064 of control information between different access points
• CPC Class Codes: H04W 36/00725 Random access channel [RACH]-less handover
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 36/249 according to timing information
• CPC Class Codes: H04W 40/36 due to handover
• CPC Class Codes: H04W 48/17 Selecting a data network PoA [Point of Attachment]
• CPC Class Codes: H04W 76/18 Management of setup rejection or failure
• CPC Class Codes: H04W 76/19 Connection re-establishment

Abstract

An enhanced connection recovery upon lost RRC connection due to radio link failure (RLF) or handover failure (HOF) is proposed. A UE first establishes an RRC connection in a source cell in a mobile communication network. Later on, the UE detects a failure event and starts an RRC reestablishment procedure in a target cell to restore the RRC connection. In a first novel aspect, a fast NAS recovery process is applied to reduce the outage time in the target cell. In a second novel aspect, context fetching is used to reduce the outage time in the target cell. In a third novel aspect, a loss-less reestablishment procedure is proposed to reduce data loss during the connection recovery.

Claims

1. A method for enhanced connection recovery, the method comprising:

receiving a radio resource control (RRC) reestablishment request message from a user equipment (UE) by a target base station in a mobile wireless communication network, wherein a serving base station information is received in the request message;

transmitting an X2 radio link failure (RLF) indication to the serving base station, wherein the X2 RLF indication comprises a UE context request and a data forwarding request;

receiving an X2 handover (HO) request message from the serving base station after transmitting the X2 RLF indication, wherein the X2 HO request message comprises UE context information, packet data convergence protocol (PDCP) serial number (SN) status transfer, and forwarded U-plane data;

transmitting a response message for RRC reestablishment to the UE after successfully receiving the UE context information; and

triggering the UE to resume a signaling radio bearer (SRB) and a security mode for the RRC reestablishment based on the UE context information in the X2 HO request message.

2. The method of claim 1, wherein the UE context information comprises UE capability information and non-access stratum (NAS) configuration information.

3. The method of claim 1, wherein the UE context information is received via an X2 interface instead of via an S1 interface.

4. The method of claim 1, wherein the RLF indication is carried via a new information element that requires mandatory response from the serving base station.

5. The method of claim 1, further comprising:

performing an RRC connection reconfiguration with the UE after transmitting the response message of RRC reestablishment to the UE.

6. The method of claim 1, further comprising:

transmitting an S1 path switch request to a mobility management entity (MME); and

receiving an S1 patch switch acknowledgement from the MME.

7. A base station, comprising:

a receiver that receives a radio resource control (RRC) reestablishment request message from a user equipment (UE) by a target base station in a mobile wireless communication network, wherein a serving base station information is received in the request message;

an X2 interface that transmits an X2 radio link failure (RLF) indication to the serving base station, wherein the X2 RLF indication comprises a UE context request and a data forwarding request, wherein the X2 interface also receives an X2 handover (HO) request message from the serving base station after transmitting the X2 RLF indication, and wherein the X2 HO request message comprises UE context information, packet data convergence protocol (PDCP) serial number (SN) status transfer, and forwarded U-plane data;

a transmitter that transmits a response message for RRC reestablishment to the UE after successfully receiving the UE context information; and

an RRC connection management circuit that triggers the UE to resume a signaling radio bearer (SRB) and a security mode for the RRC reestablishment based on the UE context information in the X2 HO request message.

8. The base station of claim 7, wherein the UE context information comprises UE capability information and non-access stratum (NAS) configuration.

9. The base station of claim 7, wherein the UE context information is received via the X2 interface instead of via an S1 interface.

10. The base station of claim 7, wherein the RLF indication is carried via a new information element that requires mandatory response from the serving base station.

11. The base station of claim 7, further comprising:

an RRC connection management module that performs an RRC connection reconfiguration with the UE after transmitting the response message of RRC reestablishment to the UE.

12. The base station of claim 7, further comprising:

an S1 interface that transmits an S1 path switch request to a mobility management entity (MME), wherein the S1 interface also receives an S1 patch switch acknowledgement from the MME.