CN112616194B

CN112616194B - Quick recovery method and system for failure of multi-connection node in communication system

Info

Publication number: CN112616194B
Application number: CN202011435599.3A
Authority: CN
Inventors: 陈瑞欣; 李雷敏; 刘为; 周晓玲; 俞春祥
Original assignee: Shanghai Institute of Microwave Technology CETC 50 Research Institute
Current assignee: Shanghai Institute of Microwave Technology CETC 50 Research Institute
Priority date: 2020-12-10
Filing date: 2020-12-10
Publication date: 2022-11-29
Anticipated expiration: 2040-12-10
Also published as: CN112616194A

Abstract

The invention provides a quick recovery method and a system when a plurality of connection nodes in a communication system fail, comprising the following steps: step 1: requesting an auxiliary node base station to establish a signaling radio bearer (SRB 3) for a terminal, packaging switching preparation information and sending the switching preparation information to an auxiliary node; step 2: detecting the link state between the main node and the auxiliary node through a Stream Control Transmission Protocol (SCTP); and step 3: the terminal detects the wireless link failure of the main node according to the out-of-step detection mechanism of the main node physical layer; and 4, step 4: when detecting that the main node fails, starting switching to the auxiliary node, and the auxiliary node base station loads switching preparation information and a packaging switching instruction on the SRB3 and sends the switching preparation information and the packaging switching instruction to the terminal; and 5: and after the terminal receives the packaging switching instruction, changing the auxiliary node into the main node. When a certain base station node fails, the terminal can quickly switch the control plane and the user plane to the nodes which do not fail, so as to improve the robustness of the system, reduce the service interruption time of the user and improve the user experience.

Description

Quick recovery method and system for failure of multi-connection node in communication system

Technical Field

The present invention relates to the field of mobile communications technologies, and in particular, to a method and a system for fast recovery when multiple connected nodes in a communication system fail.

Background

In a mobile communication system, dual-Connectivity (DC) is an important technology introduced by the 3GPP Release-12 Release. Through the dual-connection technology, the packet data service of a plurality of base station nodes can realize the convergence and distribution of user service data in a Packet Data Convergence (PDCP) layer by utilizing the existing non-ideal backhaul (X2) or Xn interface, provide higher throughput for a terminal (UE), and bring higher resource utilization rate, lower system switching delay and better robustness of a wireless link for a network.

However, the existing dual-connection architecture has certain defects in the robustness of the control plane and the user plane, and for the problem of failure of the main node in some special application scenarios, the robustness of dual-connection on the control plane and the user plane cannot meet the requirement.

As shown in fig. 1, in the dual connectivity architecture, the base station node types are divided into two types, a primary node (MN) and a Secondary Node (SN). Taking the NR dual connectivity of 5G as an example, a typical NR dual connectivity (SN terminated) separates the control plane and the signaling plane of the bearer.

Robustness to the control plane: the UE generally only keeps RRC connection with the MN, the control plane is maintained, the RRC entity always has only one node of the MN, and even if the SRB3 and the Split SRB exist, the context of the UE still needs to be maintained by the MN. Therefore, once the control plane master node MN fails, the SN cannot perform context management and control on the UE, and the UE can only initiate a network searching and accessing process at the SN or other nodes again, which results in a longer service interruption time.

Robustness to user plane: the user plane can only be terminated in one node, and the PDCP entity can only exist in one node of the MN or the SN all the time. Therefore, if the user plane terminating node fails, especially if the MN node fails, abnormal or interrupted service of the terminal may be caused. Similarly, at this time, the UE can only initiate a network searching and accessing process at the SN or other nodes again, and there is a large service interruption time.

Patent document CN100452797C (application number: 200510012192.9) discloses a high-availability distributed border gateway protocol system based on a cluster router structure, in which one node is selected as a master node, another node is a backup node of the master node, a connection node, and at least one slave node.

Disclosure of Invention

In view of the defects in the prior art, an object of the present invention is to provide a method and a system for fast recovery when a multi-connection node in a communication system fails.

The method for quickly recovering the failure of the multi-connection node in the communication system comprises the following steps:

step 1: in the multi-connection establishment process, when the main node base station responds to the auxiliary node addition request, the auxiliary node base station is requested to establish a signaling radio bearer (SRB 3) for the terminal and package switching preparation information to be sent to the auxiliary node;

and 2, step: detecting the link state between the main node and the auxiliary node by using a Stream Control Transmission Protocol (SCTP);

and step 3: the terminal detects the wireless link failure of the main node according to the out-of-step detection mechanism of the main node physical layer;

and 4, step 4: when the failure of the main node is detected during the wireless link failure detection, switching is started for the auxiliary node, and the auxiliary node base station loads switching preparation information and an encapsulation switching instruction on the SRB3 and sends the switching preparation information and the encapsulation switching instruction to the terminal;

and 5: and after the terminal receives the packaging switching instruction, changing the auxiliary node into the main node.

Preferably, a data packet transmission confirmation detection mechanism is adopted to confirm the request transmitted by the secondary node base station and the request received by the primary node base station.

Preferably, the stream control transmission protocol SCTP is configured, a non-buffered immediate transmission strategy is adopted, the maximum retransmission times of the connection of the SCTP are reduced, the time length of a transmission timeout timer is reduced, the size of a sliding window is reduced, and the node failure condition is rapidly detected;

the configured parameters are configured by the main node or the auxiliary node according to requirements.

Preferably, setting configuration parameters of wireless link failure detection, including reducing out-of-step detection times and reducing out-of-step detection timer duration;

when the terminal accesses the configuration parameters of the wireless link failure detection, the main node or the auxiliary node sends the configuration parameters to the terminal through the reconfiguration message.

Preferably, the node failure includes the following cases:

the user plane terminating node is the master node, the master node failing;

the user plane terminating node is the primary node and the secondary node fails;

-the user plane terminating node is a secondary node, the primary node is disabled;

-the user plane terminating node is a secondary node, the secondary node failing.

The invention provides a rapid recovery system when a multi-connection node in a communication system fails, which comprises:

a module M1: in the multi-connection establishment process, when the main node base station responds to the auxiliary node addition request, the auxiliary node base station is requested to establish a signaling radio bearer (SRB 3) for the terminal and package switching preparation information to be sent to the auxiliary node;

a module M2: detecting the link state between the main node and the auxiliary node by using a Stream Control Transmission Protocol (SCTP);

a module M3: the terminal detects the wireless link failure of the main node according to the out-of-step detection mechanism of the main node physical layer;

a module M4: when the failure of the main node is detected during the wireless link failure detection, switching is started for the auxiliary node, and the auxiliary node base station loads switching preparation information and an encapsulation switching instruction on the SRB3 and sends the switching preparation information and the encapsulation switching instruction to the terminal;

a module M5: and after the terminal receives the packaging switching instruction, changing the auxiliary node into the main node.

Preferably, setting configuration parameters of wireless link failure detection, including reducing the value of out-of-step detection times and reducing the duration of an out-of-step detection timer;

Preferably, the node failure includes the following cases:

-the user plane terminating node is a master node, the master node failing;

-the user plane terminating node is a secondary node, the primary node is failed;

Compared with the prior art, the invention has the following beneficial effects: when a certain base station node fails, the terminal can rapidly switch the control plane and the user plane to the node which does not fail, so as to improve the robustness of the system, reduce the service interruption time of the user and improve the user experience.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a schematic diagram of a dual link architecture;

FIG. 2 is a flow chart of the method of the present invention.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.

Example 1:

according to the quick recovery method when the multi-connection node fails, when an MN initiates an auxiliary node adding request to an SN, switching preparation information which is possible to be switched to the SN later is carried to the SN in advance, the SN is requested to establish an SRB3, and a part of control surface guarantee is provided for the subsequent node failure in advance.

For the failure detection of the node, the following two detection methods are included:

SCTP state detection: the state detection of the SCTP link is used between the MN node and the SN node, and because the heartbeat detection time of the SCTP link is usually slow, a data packet sending confirmation detection mechanism is mainly adopted. The detection timer parameters are configured by the MN or SN as needed.

RLF detection: the RLF detection is performed by the UE on the radio link failure of the node, and here, the RLF detection mainly depends on an out-of-synchronization failure detection mechanism of a physical layer. And the detection timer parameter MN or SN is sent to the UE through the reconfiguration message.

For several node failure scenarios that may exist:

scene 1: the user plane terminating node is MN, and the MN node fails.

When the MN initiates a secondary node addition request of the SN, it requests to establish SRB3, and additionally, it also needs to additionally carry handover preparation information in advance, where the additional information includes:

after the MN node fails, the UE detects and finds out of synchronization with the MN node through RLF, and sends failure information to the SN by using SRB3. The SN tries to forward to the MN for processing, if the SN can successfully send the MN, the SN indicates that the MN is not invalid, and a fast MN recovery process of the 3GPP standard is started; and once the successful transmission fails or the MN node is found to have failed through SCTP status detection, a handover procedure to the SN node may be initiated:

the SN firstly judges 'GUAMI', if the serving AMF is consistent with the MN, the process can be started; the SN establishes SRB and DRB by taking the own cell of the SN as a target cell according to RRC configuration information carried by the MN when the SN adds the request and the current radio bearing information of the SN; derive keys as Kgnb and NH in "association Information"; because the PDCP entity is at the MN, the previous PDCP sequence number is maintained by the MN, and the SN does not maintain the PDCP sequence number, the 'fullconfig' is needed for setting; the SN establishes UE context according to the information, generates RRC reconfiguration information, and directly sends the RRC reconfiguration information to the UE by utilizing the SRB 3; after the UE completes the synchronization to the SN target cell, the SN requests the core network to switch the user plane path to the SN according to the 'Source AMF UE NGAP ID'. Because of being "fullconfig", the PDCP sequence number is recalculated, which may cause a small amount of packet loss, and the scheme can be used to achieve "seamless" handover with only a short service interruption time.

For the case that the SN does not completely obtain all the service bearers in the secondary node addition request, the session bearer addition process may be triggered by the UE or the core network to recover all the service bearers.

Scene 2: the user plane terminating node is MN, and the SN node fails.

After the failure of the SCTP status detection or the RLF detection, the SCG failure procedure of the 3GPP standard can be followed without any service interruption time.

Scene 3: the user plane termination node is SN, and the MN node fails.

Similar to scenario 1, but because the PDCP entity is in the SN, the previous PDCP sequence number is maintained by the SN, so "fullconfig" may not be set in the RRC reconfiguration for handover, and the PDCP sequence number of the user plane may directly continue with the previous sequence number, and no packet loss occurs.

Scene 4: the user plane termination node is SN, and the SN node fails.

After the SCTP state detection or the RLF detection fails, the MN may initiate a path update procedure, which may result in a short service interruption time.

Example 2:

as shown in fig. 2, the method for fast recovery when a multi-connection node in a communication system fails according to the present invention includes:

step 0a.UE accesses to a main node cell and establishes wireless bearing to transmit user service data;

step 0b.UE reports that the SN cell signal quality meets the double-connection requirement.

And step 1. The MN initiates an auxiliary node adding request to the SN, requests the SN to establish the SRB3 and the DRB and carries relevant information of switching preparation. The handover preparation related information includes UE identity of MN to core network, AS security key allocated by MN for SN, and RRC related configuration of MN.

Sn establish SRB3 and DRB in step 2a.

And 2b, maintaining relevant information of the switching preparation carried by the MN.

And 3.SN encapsulation double connection indication, and sending auxiliary node addition request response to MN.

And 3a, if the SN is terminated, the MN needs to send an Xn-U address indication to the SN.

And 4, the MN sends the dual connection instruction to the UE by using the RRC reconfiguration message.

And 5, establishing the SRB3 and the DRB by the UE.

And 6, the UE sends the reconfiguration completion to indicate that the MN double connection is completed.

Step 7. The mn indicates that the SN dual connectivity is complete.

And 8, the UE completes the random access process to the SN, and the SRB3, the DRB and the SN complete synchronization.

And 9, if the SN is terminated, the MN needs to send the serial number state to be forwarded to the SN, so that the SN can obtain the serial number of the current PDCP.

And step 10, if the SN is terminated, the MN forwards data for the SN.

And step 11. The MN and the core network complete the path updating process.

And step 12. The UE continuously performs Radio Link Failure (RLF) detection on the MN.

And step 13. The UE detects the RLF of the MN and assembles failure information into the SRB3.

And step 14. The UE sends failure information to the SN by utilizing the SRB3. The Failure Information may be Failure Information or Mcg Failure Information.

Step 14a.sn keeps making SCTP link detection for the MN. The SN tries to forward the failure information to the MN for processing, if the failure information can be successfully sent, the MN is not invalid, and a fast recovery process of the MN in the 3GPP standard is started; and once the successful transmission fails or the MN node is found to have failed through SCTP status detection, a handover procedure to the SN node can be initiated.

Step 15.SN generates switching instruction according to the switching preparation information maintained in step 2 b; the handover command contains SRB1, SRB2 and DRB, and the configuration follows the RRC configuration of the MN in handover preparation as much as possible; the switching command includes an indication of deletion of SRB 3; if the MN is terminated, the switching instruction needs to contain a fullconfig field; if the SN is terminated, the switching instruction does not need to contain a fullconfig field;

step 16. The sn sends the RRC reconfiguration through SRB3 to send a handover command to the UE.

And step 17, the UE receives the switching instruction, initiates a random access process of the SN, and completes cell synchronization with the SN.

And step 18. The UE sends RRC reconfiguration complete indication SN switching completion through the SRB 1.

And 19, the SN initiates a path switching process to inform the core network that the user plane of the UE is switched to the SN according to the UE identification from the MN to the core network in the switching preparation message, and the SN can continue the user plane service transmission after the switching is finished.

And 20, if the SN does not completely obtain all the service bearers in the auxiliary node adding request of the step 1, triggering a session bearer adding process by the UE or the core network to recover all the service bearers.

Those skilled in the art will appreciate that, in addition to implementing the systems, apparatus, and various modules thereof provided by the present invention in purely computer readable program code, the same procedures can be implemented entirely by logically programming method steps such that the systems, apparatus, and various modules thereof are provided in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers and the like. Therefore, the system, the device and the modules thereof provided by the present invention can be considered as a hardware component, and the modules included in the system, the device and the modules thereof for implementing various programs can also be considered as structures in the hardware component; modules for performing various functions may also be considered to be both software programs for performing the methods and structures within hardware components.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.

Claims

1. A method for fast recovery in the event of a failure of a multi-connection node in a communication system, comprising:

step 2: detecting the link state between the main node and the auxiliary node by using a Stream Control Transmission Protocol (SCTP);

and 3, step 3: the terminal detects the wireless link failure of the main node according to the out-of-step detection mechanism of the main node physical layer;

2. The method as claimed in claim 1, wherein a data packet transmission acknowledgement detection mechanism is used to acknowledge the request transmitted by the secondary node base station and the request received by the primary node base station.

3. The method according to claim 1, wherein stream control transmission protocol SCTP is configured, and a non-buffered immediate transmission strategy is adopted, including reducing the maximum retransmission times of SCTP connections, reducing the duration of a transmission timeout timer, and reducing the size of a sliding window, to perform rapid detection on a node failure condition;

4. The method according to claim 1, wherein the configuration parameters for detecting the failure of the radio link are set to include a value for reducing the number of out-of-step detections and a duration for reducing an out-of-step detection timer;

5. The method of claim 1, wherein the node failure comprises:

-the user plane terminating node is a master node, the master node failing;

the user plane terminating node is the secondary node, the secondary node failing.

6. A system for fast recovery in the event of a multi-connection node failure in a communication system, comprising:

a module M1: in the process of establishing multi-connection, when a main node base station responds to an auxiliary node adding request, the main node base station requests an auxiliary node base station to establish a signaling radio bearer (SRB 3) for a terminal and encapsulates switching preparation information to send the switching preparation information to an auxiliary node;

7. The system of claim 6, wherein a packet transmission acknowledgement detection mechanism is used to acknowledge the request transmitted by the secondary node base station and the request received by the primary node base station.

8. The system according to claim 6, wherein the stream control transmission protocol SCTP is configured, and a non-buffered immediate transmission strategy is adopted, including reducing the maximum retransmission times of the SCTP connection, reducing the time length of the transmission timeout timer, and reducing the size of the sliding window, to quickly detect the node failure;

9. The system according to claim 6, wherein the configuration parameters for detecting the failure of the radio link are set to include a value for reducing the number of out-of-step detections and a duration of an out-of-step detection timer;

10. A system for rapid recovery in the event of a multi-connectivity node failure in a communication system according to claim 6, wherein a node failure comprises the following:

the user plane terminating node is the master node, the master node failing;