CN117641476A

CN117641476A - Link switching method, device and system

Info

Publication number: CN117641476A
Application number: CN202211026031.5A
Authority: CN
Inventors: 姚琴波; 戴振华; 陈肃慧
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2022-08-25
Filing date: 2022-08-25
Publication date: 2024-03-01

Abstract

The embodiment of the application provides a link switching method, a device and a system, which are used for returning to a source gNB to continue service transmission under the conditions that a terminal device fails to access a target gNB and the connection with the source gNB is normal. The method comprises the following steps: the terminal equipment determines that the switching from the first link to the second link fails and the first link is in a connection state; the terminal equipment sends first indication information with a serial number SN of n+1 to first network equipment; the first indication information is used for indicating the switching failure of the terminal equipment from the first link to the second link, N is SN of a first signaling sent by the terminal equipment to the first network equipment before the terminal equipment triggers the switching from the first link to the second link, and N is a positive integer; in the case that the terminal equipment receives the first message from the first network equipment, the terminal equipment sends a second signaling with SN of 0 to the first network equipment; the first message is used for the first network equipment to confirm that the first indication information is received.

Description

Link switching method, device and system

Technical Field

The present disclosure relates to the field of communications technologies, and in particular, to a method, an apparatus, and a system for link switching.

Background

To avoid interruption of traffic transmission between the terminal device and the base station during cell handover, and to increase reliability of communication, dual active protocol stacks (dual active protocol stack, DAPS) have been developed.

In the DAPS scenario, after receiving the handover command, the terminal device still maintains the radio resource control (radio resource control, RRC) connection with the source next generation base station (gNB), and does not release the RRC connection with the source gNB until the access to the target gNB is successful. And under the condition that the access of the terminal equipment to the target gNB fails and the connection between the terminal equipment and the source gNB is normal, the terminal equipment is expected to return to the source gNB to continue the service transmission.

However, in the prior art, when the terminal device sends information for indicating handover failure to the source gNB without reestablishing radio link control (radio link control, RLC) by the source gNB, the sequence number of the information is likely not to be within the receiving window of the source gNB and is discarded by the source gNB. In this way, the terminal device cannot receive feedback information from the source gNB, i.e. the terminal device considers that the RRC connection with the source gNB is broken. Further, the terminal device triggers an RRC reestablishment procedure, i.e. first cell selection, and sends an RRC reestablishment request to the base station to which the selected cell belongs (RRC ReestablishmentRequest) in an attempt to restore the RRC connection. Obviously, the triggering of the RRC reestablishment procedure by the terminal device is not in line with the desire to continue traffic transmission back to the source gNB.

Disclosure of Invention

The embodiment of the application provides a link switching method, a device and a system, which are used for returning to a source gNB to continue service transmission under the conditions that a terminal device fails to access a target gNB and the connection with the source gNB is normal.

In order to achieve the above purpose, the embodiments of the present application adopt the following technical solutions:

in a first aspect, a link switching method is provided, where an apparatus for performing the link switching method may be a terminal device, and may be a module applied in the terminal device, for example, a chip or a chip system. The following describes an example in which an execution subject is a terminal device. The method comprises the steps that a terminal device determines that switching from a first link to a second link fails and the first link is in a connection state, wherein the first link is a link between the terminal device and first network equipment, and the second link is a link between the terminal device and second network equipment; the terminal equipment sends first indication information to the first network equipment; the first indication information is used for indicating that the terminal equipment fails to switch from the first link to the second link, the serial number SN of the first indication information is N+1, N is the SN of a first signaling sent by the terminal equipment to the first network equipment before the terminal equipment triggers the switching from the first link to the second link, and N is a positive integer; in case the terminal device receives a first message from the first network device, the terminal device sends a second signaling to the first network device; wherein the first message is used for the first network device to confirm that the first indication information is received, and SN of the second signaling is 0.

In the link switching method provided in the embodiment of the present application, after the first network device receives the first signaling with SN of N, if the first network device does not reconstruct RLC, the initial SN of the receiving window of the first network device is n+1, that is, the SN of the receiving window of the first network device includes n+1. Since SN of the first indication information indicating the link switching failure sent by the terminal device is n+1 and falls within the receiving window of the first network device, the first network device sends the first message to the terminal device after receiving the first indication information. The terminal equipment can judge that the connection with the first network equipment is normal through the received first message, and then the terminal equipment returns to the first network equipment to continue the transmission of the second signaling after the switching failure.

With reference to the first aspect, in a possible implementation manner, the link switching method provided in the embodiment of the present application further includes: in the case that the terminal device does not receive the first message from the first network device, the terminal device sends second indication information to the first network device and receives a second message from the first network device; the second indication information is used for indicating that the terminal equipment fails to switch from the first link to the second link, the SN of the second indication information is 0, and the second message is used for the first network equipment to confirm that the second indication information is received.

In the link switching method provided in the embodiment of the present application, after the first network device receives the first signaling with SN being N, if the first network device reestablishes RLC, the receiving window of the first network device is set to an initial state, that is, the initial SN of the receiving window of the first network device is 0, and the receiving window of the first network device is likely not to include n+1. Because SN of the first indication information sent by the terminal device and indicating the link switching failure is n+1, the SN does not fall in the receiving window of the first network device, and therefore, the first network device discards the received first indication information and does not send the first message to the terminal device. But after the first indication information, the terminal device also sends second indication information with SN of 0 to the first network device. Since SN of the second indication information is 0 and falls within the receiving window of the first network device, the first network device may send the second message to the terminal device after receiving the second indication information. The terminal equipment can judge that the connection with the first network equipment is normal through the received second message, and then the terminal equipment returns to the first network equipment to continue signaling transmission after the switching failure.

With reference to the first aspect, in a possible implementation manner, after the terminal device sends the first indication information to the first network device and before the terminal device sends the second indication information to the first network device, the method further includes: the terminal device resends the first indication information to the first network device. In this scheme, the retransmission of the first indication information may exclude that the first network device does not normally receive the first indication information due to other reasons than that the SN of the receiving window of the first network device does not include n+1.

With reference to the first aspect, in a possible implementation manner, the link switching method provided in the embodiment of the present application further includes: the terminal equipment starts a timer with a timing duration of a first duration at a first moment; the first time is the time when the terminal equipment sends the first indication information, or the first time is the time when the terminal equipment sends the first indication information, and is a second time long from the time when the terminal equipment sends the first indication information; the terminal device not receiving the first message from the first network device, comprising: the terminal device still does not receive the first message from the first network device after the timer expires. In this scheme, the terminal device may set a timer, and trigger the transmission of the second indication information when the timer expires and the first message is not received.

In a second aspect, a link switching method is provided, and an apparatus for performing the link switching method may be a first network device, and may be a module, such as a chip or a chip system, applied in the first network device. The following describes an example in which the execution body is a first network device. The method comprises the steps that first indication information from terminal equipment is received by first network equipment; the first indication information is used for indicating the switching failure of the terminal equipment from the first link to the second link, wherein the first link is a link between the terminal equipment and the first network equipment, the second link is a link between the terminal equipment and the second network equipment, the serial number SN of the first indication information is N+1, N is an SN of a first signaling sent by the terminal equipment to the first network equipment before the terminal equipment triggers the switching from the first link to the second link, and N is a positive integer; in the case that the SN of the receiving window of the first network device includes n+1, the first network device sends a first message to the terminal device; wherein the first message is used for the first network device to confirm that the first indication information is received; the first network device receives a second signaling from the terminal device, where SN of the second signaling is 0.

With reference to the first aspect, in a possible implementation manner, the link switching method provided in the embodiment of the present application further includes: discarding, by the first network device, the first indication information if the SN of the receive window of the first network device does not include n+1; the first network device receives second indication information from the terminal device; the second indication information is used for indicating that the terminal equipment fails to switch from the first link to the second link, and the SN of the second indication information is 0; in the case that the SN of the receiving window of the first network device includes 0, the first network device transmits a second message to the terminal device; wherein the second message is used for the first network device to confirm that the second indication information is received.

The technical effects caused by any possible implementation manner of the second aspect may be referred to the technical effects caused by the foregoing first aspect or the different implementation manners of the first aspect, which are not described herein.

In a third aspect, a communication device is provided for implementing the above method. The communication device comprises corresponding modules, units or means (means) for implementing the above method, where the modules, units or means may be implemented by hardware, software, or implemented by hardware executing corresponding software. The hardware or software includes one or more modules or units corresponding to the functions described above.

With reference to the third aspect, in one possible implementation manner, the communication apparatus includes: a transceiver module and a processing module; the processing module is configured to determine that a handover from a first link to a second link fails and the first link is in a connection state, where the first link is a link between the communication device and a first network device, and the second link is a link between the communication device and a second network device; the transceiver module is used for sending first indication information to the first network equipment; the first indication information is used for indicating that the communication device fails to switch from the first link to the second link, the serial number SN of the first indication information is n+1, N is SN of a first signaling sent to the first network device through the transceiver module before the communication device triggers the switching from the first link to the second link, and N is a positive integer; the transceiver module is further configured to send a second signaling to the first network device if a first message from the first network device is received; wherein the first message is used for the first network device to confirm that the first indication information is received, and SN of the second signaling is 0.

With reference to the third aspect, in a possible implementation manner, the transceiver module is further configured to send second indication information to the first network device and receive a second message from the first network device if the first message from the first network device is not received; the second indication information is used for indicating that the communication device fails to switch from the first link to the second link, the SN of the second indication information is 0, and the second message is used for the first network equipment to confirm that the second indication information is received.

With reference to the third aspect, in a possible implementation manner, the transceiver module is further configured to retransmit the first indication information to the first network device.

With reference to the third aspect, in a possible implementation manner, the processing module is further configured to start a timer with a timing duration of a first duration at a first time; the first time is the time when the transceiver module transmits the first indication information, or the first time is the time when the transceiver module transmits the first indication information, and is a second time long from the time when the transceiver module transmits the first indication information; the transceiver module, further configured to not receive the first message from the first network device, includes: for not yet receiving the first message from the first network device after the timer has expired.

The technical effects caused by any possible implementation manner of the third aspect may be referred to the technical effects caused by the foregoing first aspect or the different implementation manners of the first aspect, which are not described herein.

In a fourth aspect, a communication device is provided for implementing the above method. The communication device comprises corresponding modules, units or means (means) for implementing the above method, where the modules, units or means may be implemented by hardware, software, or implemented by hardware executing corresponding software. The hardware or software includes one or more modules or units corresponding to the functions described above.

With reference to the fourth aspect, in one possible implementation manner, the communication device includes: a transceiver module; the receiving and transmitting module is used for receiving first indication information from the terminal equipment; the first indication information is used for indicating the switching failure of the terminal equipment from the first link to the second link, wherein the first link is a link between the terminal equipment and the communication device, the second link is a link between the terminal equipment and the second network equipment, the serial number SN of the first indication information is N+1, N is the SN of a first signaling sent by the terminal equipment to the communication device before the terminal equipment triggers the switching from the first link to the second link, and N is a positive integer; the transceiver module is further configured to send a first message to the terminal device when the SN of the receiving window of the communication device includes n+1; wherein the first message is used for the communication device to confirm that the first indication information is received; the transceiver module is further configured to receive a second signaling from the terminal device, where SN of the second signaling is 0.

With reference to the fourth aspect, in one possible implementation manner, the communication apparatus further includes: a processing module; the processing module is configured to discard the first indication information if SN of the receiving window of the communication device does not include n+1; the transceiver module is further used for receiving second indication information from the terminal equipment; the second indication information is used for indicating that the terminal equipment fails to switch from the first link to the second link, and the SN of the second indication information is 0; the transceiver module is further configured to send a second message to the terminal device if the SN of the receiving window of the communication device includes 0; wherein the second message is used for the communication device to confirm that the second indication information is received.

The technical effects caused by any possible implementation manner of the fourth aspect may be referred to the technical effects caused by the foregoing first aspect or the different implementation manners of the first aspect, which are not described herein.

In a fifth aspect, a communication system is provided, comprising a second network device, a terminal device performing the method of the first aspect, and a first network device performing the method of the second aspect.

The technical effects of the fifth aspect may be referred to the technical effects of the first aspect or the different implementation manners of the first aspect, which are not described herein.

In a sixth aspect, there is provided a communication apparatus comprising: a processor; the processor is configured to perform the method according to the first or second aspect described above in response to computer instructions stored in the memory after being coupled to the memory and read the instructions.

With reference to the sixth aspect, in a possible implementation manner, the communication device further includes a memory; the memory is used to store computer instructions.

With reference to the sixth aspect, in a possible implementation manner, the communication device further includes a communication interface; the communication interface is used for the communication device to communicate with other equipment. By way of example, the communication interface may be a transceiver, an input/output interface, an interface circuit, an output circuit, an input circuit, a pin or related circuit, or the like.

With reference to the sixth aspect, in a possible implementation manner, the communication device may be a chip or a chip system. When the communication device is a chip system, the communication device may be formed by a chip, or may include a chip and other discrete devices.

With reference to the sixth aspect, in one possible implementation manner, when the communication device is a chip or a chip system, the communication interface may be an input/output interface, an interface circuit, an output circuit, an input circuit, a pin, or a related circuit on the chip or the chip system, or the like. The processor described above may also be embodied as processing or logic circuits.

The technical effects caused by any possible implementation manner of the sixth aspect may be referred to the technical effects caused by the foregoing first aspect or the different implementation manners of the first aspect, which are not described herein.

In a seventh aspect, there is provided a computer readable storage medium having instructions stored therein which, when run on a computer, cause the computer to perform the method of any of the above aspects.

The technical effects of the seventh aspect may be referred to the technical effects of the first aspect or the different implementation manners of the first aspect, which are not described herein.

In an eighth aspect, there is provided a computer program product comprising instructions which, when run on a computer, cause the computer to perform the method of any of the above aspects.

The technical effects of the eighth aspect may be referred to the technical effects of the first aspect or the different implementation manners of the first aspect, which are not described herein.

Drawings

FIG. 1 is a diagram of a control plane protocol stack in a prior art mobile communication technology;

fig. 2 is a flow chart of cell handover in the scenario of a single active protocol stack in the prior art;

FIG. 3 is a flowchart of a cell handoff in a DAPS scenario in the prior art;

fig. 4 is a flow chart of RRC reestablishment in the prior art;

FIG. 5 is a schematic diagram of a protocol structure of a sender in the prior art;

FIG. 6 is a schematic diagram of another protocol structure of a sender in the prior art;

fig. 7 is a schematic diagram of a protocol structure of a receiver in the prior art;

FIG. 8 is a flowchart II of a cell handoff in a DAPS scenario in the prior art;

fig. 9 is a schematic architecture diagram of a communication system according to an embodiment of the present application;

fig. 10 is a schematic structural diagram of a first network device and a terminal device provided in an embodiment of the present application;

fig. 11 is a schematic diagram of a specific structure of a terminal device provided in an embodiment of the present application;

fig. 12 is a flowchart of a link switching method provided in an embodiment of the present application;

Fig. 13 is a second flowchart of a link switching method provided in the embodiment of the present application;

fig. 14 is a schematic structural diagram of a communication device according to an embodiment of the present application.

Detailed Description

For the convenience of understanding the technical solutions of the embodiments of the present application, a brief description of related technologies or terms of the present application is given below.

First, a control plane protocol stack in mobile communication technology.

In the third generation partnership project (3rd generation partnership project,3GPP) -38300 standard protocol, as shown in fig. 1, a non-access-stratum (NAS) layer of a User Equipment (UE) may interact with a NAS of an access and mobility management function (access and mobility management function, AMF) in a core network, and an RRC layer of the UE may interact with an RRC layer of a gNB in an access network. Similarly, the packet data convergence protocol (packet data convergence protocol, PDCP) layer of the UE may interact with the PDCP layer of the gNB. The RLC layer of the UE may interact with the RLC layer of the gNB. The media access control (media access control, MAC) layer of the UE may interact with the MAC layer of the gNB. The Physical (PHY) layer of the UE may interact with the PHY layer of the gNB.

In the scenario of a single active protocol stack, the protocol stacks of each layer of the UE have only one. But in the DAPS scenario, there are two shares of PDCP, RLC, MAC and PHY of the UE based on the RRC configuration, and both are in active state at the same time.

Second, cell switching procedure under the scene of single activation protocol stack.

As shown in fig. 2, after the UE accesses the source gNB and completes the security activation, capability query, and bearer configuration, the following steps may be performed:

in step S201, the source gNB may send a measurement configuration message to the UE. Accordingly, the UE may receive a measurement configuration message from the source gNB.

The measurement configuration message may include, among other things, a measurement object (measurement object), e.g. a frequency point or cell to be measured. The measurement configuration message may further include a condition related to the parameter value, and when the parameter value measured by the UE satisfies the condition in the measurement configuration message, a measurement report is sent to the source gNB, that is, execution of step S203 described below is triggered.

In step S202, the UE may send a configuration complete message to the source gNB. Accordingly, the source gNB may receive a configuration complete message from the UE.

Step S203, the UE may send a measurement report to the source gNB (measurement report). Accordingly, the source gNB may receive measurement reports from the UE.

For example, the execution of step S203 may be triggered when the parameter value measured by the UE satisfies the condition in the measurement configuration message.

In step S204, when the source gNB determines that the handover condition is satisfied according to the measurement report, the source gNB may send a handover request to the target gNB. Accordingly, the target gNB may receive a handover request from the source gNB.

In step S205, the target gNB may send a handover request reply to the source gNB. Accordingly, the source gNB may receive a handover request reply from the target gNB.

In step S206, the source gNB may send a handover command to the UE. Accordingly, the UE may receive a handover command from the source gNB.

The handover command may be an RRC reconfiguration message (rrcrecon configuration), for example.

In step S207, after receiving the handover command, the UE may perform handover from the source gNB to the target gNB. For example, the UE may perform uplink synchronization and downlink synchronization for the target base station.

In step S207, the UE needs to disconnect the RRC connection with the source gNB when performing handover from the source gNB to the target gNB.

In step S208a, if the handover is successful, the UE may send a handover complete message to the target gNB after the handover. Accordingly, the target gNB may receive a handover complete message from the UE.

The handover complete message may be an RRC reconfiguration complete message, for example.

In step S208b, if the handover fails, the UE may trigger the RRC reestablishment procedure.

In the embodiment of the present application, the UE triggers an RRC reestablishment procedure, that is, the UE may perform cell search, and initiate an RRC reestablishment request (RRCReestablishmentRequest) to a base station to which the searched cell belongs.

In this embodiment of the present application, the base station to which the searched cell belongs may or may not be the source gNB. Fig. 2 schematically shows a flowchart when the base station to which the searched cell belongs is the source gNB.

Third, cell handover procedure in DAPS scenario.

As shown in fig. 3, after the UE accesses the source gNB and completes the security activation, capability query, and bearer configuration, steps S201 to S205 may be performed, and the detailed description may refer to the embodiment shown in fig. 2, which is not repeated herein. After step S205, the following steps may be performed:

in step S306, the source gNB may send a DAPS handoff command to the UE. Accordingly, the UE may receive a DAPS handoff command from the source gNB.

Illustratively, the DAPS handoff command may be an RRC reconfiguration message (RRCRECONfigure). The RRC reconfiguration message includes configuration information of one or more bearers, and the configuration information is used for characterizing that at least one bearer meets the DAPS attribute.

In step S307, after receiving the handover command, the UE may perform handover from the source gNB to the target gNB.

For example, the UE may perform uplink synchronization and downlink synchronization for the target base station.

Unlike step S207 in the scenario of a single active protocol stack, in step S307, the UE may still maintain the RRC connection with the source gNB when performing a handover from the source gNB to the target gNB.

If the handover is successful, the following steps S308a to S311a are performed:

in step S308a, the UE may send a handover complete message to the target gNB after the handover. Accordingly, the target gNB may receive a handover complete message from the UE.

In step S309a, the target gNB may send information to the UE instructing the UE to release the RRC connection with the source gNB. Accordingly, the UE may receive information from the target gNB instructing the UE to release the RRC connection with the source gNB.

Step S310a, the UE releases the RRC connection with the source gNB.

In step S311a, the UE may send an RRC connection complete message to the target gNB to release the UE from the source gNB. Accordingly, the target gNB may receive an RRC connection complete message from the UE that releases the UE from the source gNB.

For example, the RRC connection complete message that releases the UE and the source gNB may be an RRC reconfiguration complete message.

If the handover fails and the RRC connection of the UE with the source gNB is normal, the following step S308b is performed:

step S308b, the UE may send failure information to the source gNB (failure information). Accordingly, the source gNB may receive failure information from the UE.

If the handover fails and the RRC connection of the UE with the source gNB is broken, the following step S308c is performed:

Step S308c, the UE may trigger the RRC reestablishment procedure.

In the embodiment of the present application, the UE triggers an RRC reestablishment procedure, that is, the UE may perform cell search and initiate an RRC reestablishment request to a base station to which the searched cell belongs.

Fourth, RRC reestablishment procedure.

The RRC reestablishment procedure in the New Radio (NR) system defined by the 3GPP-38300 standard protocol is described below as an example. Specifically, as shown in fig. 4, the RRC reestablishment procedure in the NR system includes the following steps:

in step S401, the UE may send an RRC reestablishment request to the gNB. Accordingly, the gNB may receive an RRC reestablishment request from the UE.

In conjunction with fig. 2, the gNB in the embodiment shown in fig. 4 may be a base station to which the cell searched by the UE in step S208b in the embodiment shown in fig. 2 belongs; alternatively, in conjunction with the foregoing fig. 3, the gNB in the embodiment shown in fig. 4 may be a base station to which the cell searched by the UE in step S308c in the embodiment shown in fig. 3 belongs.

The UE in the embodiment shown in fig. 4 may be in an RRC connected state (rrc_connected), and the UE may be in a connection management connected state (connection management _connected, cm_connected) on the NAS layer.

Steps S402, gNB may send a retrieve UE context request to the last service gNB (last servinggNB) (retrieve UE context request). Accordingly, the last serving gNB may receive a retrieve UE context request from the gNB.

In connection with the above described fig. 2 or fig. 3, the last service gNB in the embodiment shown in fig. 4 may be the source gNB in the embodiment shown in fig. 2 or fig. 3. Similarly, in the embodiment shown in fig. 4, the gNB may or may not be the last serving gNB.

Step S403, the last service gNB may send a retrieve context answer to the gNB (retrieve UE context response). Accordingly, the gNB may receive a retrieve context reply from the last serving gNB.

Step S404, the gNB may send an RRC reestablishment (rrcreestablight) message to the UE. Accordingly, the UE may receive an RRC reestablishment message from the gNB.

Illustratively, step S404 may be used for security authentication. For example, whether or not the network deployment between the gNB and the last serving gNB is secure, or whether or not steps S402 and S403 are normally performed.

Alternatively, the following step S405 may be performed:

steps S405, gNB may send an RRC reconfiguration (rrcrecon configuration) message to the UE. Accordingly, the UE may receive an RRC reconfiguration message from the gNB.

Illustratively, the RRC reconfiguration message is used to activate configuration information in the UE, or to add, delete or modify configuration information already present in the UE.

In response to step S404, the UE may send an RRC reestablishment complete (rrcreestablischentcomplete) message to the gNB. Accordingly, the gNB may receive an RRC reestablishment complete message from the UE.

Alternatively, the following step S405a may be performed:

in response to step S405, the UE may send an RRC reconfiguration complete (rrcrecon complete) message to the gNB. Accordingly, the gNB may receive an RRC reconfiguration complete message from the UE.

Alternatively, the following steps S406 and S407 may be performed:

steps S406, gNB may send an XN-U interface address indication (XN-U address indication) message to the last serving gNB. Accordingly, the last serving gNB may receive the XN-U interface address indication message from the gNB.

In step S407, the last serving gNB may send a Sequence Number (SN) state transfer (status transfer) message to the gNB. Accordingly, the gNB may receive the SN status transfer message from the last serving gNB.

Steps S408, gNB may send a path switch request to the AMF (path switch request). Accordingly, the AMF may receive a path switch request from the gNB.

Steps S409, AMF may send a path switch request reply to the gNB (path switch request response). Accordingly, the gNB may receive a path switch request reply from the AMF.

Steps S410, gNB may send a UE context release (UE context release) message to the last serving gNB. Accordingly, the last serving gNB may receive the UE context release message from the gNB.

Fifth, RLC SN protocol format.

Generally, the SN may be a sequence number used in the data transmission process. The sender sends data carrying SN according to the protocol structure, and the receiver replies a feedback message to the sender according to the SN of the received data so as to inform the sender of which data are received and which data are not received.

Illustratively, fig. 5 shows a protocol architecture diagram of the sender. The acknowledged mode data (acknowledged mode data, AMD) protocol data unit (protocol data unit, PDU) may have this structure. The structure includes a data or control (D/C) field, a poll (P) field, a segmentation information (segment information, SI) field, an SN field, and a data field. Wherein the D/C field may occupy 1 bit, the P field may occupy 1 bit, the SI field may occupy 2 bits, the SN field may occupy 12 bits, and the data field may occupy 1 or more bytes. 1 byte consists of 8 bits.

Illustratively, fig. 6 shows another protocol architecture diagram of the sender. AMD PDUs may have this structure. On the basis of the structure shown in fig. 5, the structure shown in fig. 6 further includes a Segment Offset (SO) field of 2 bytes.

Illustratively, fig. 7 shows a protocol architecture diagram of the receiving party. A status PDU may have this structure. The structure includes a D/C field, a Control PDU Type (CPT) field, a sequence number (ack_sn) field for acknowledging received data, an extension (E) 1 field, an E2 field, an E3 field, a reserved (R) field, an SO start (SOstart) field, an SO end (SOend) field, a range (negative acknowledgement range, NACK range) field for acknowledging non-received data, and a sequence number (nack_sn) field for acknowledging non-received data. Wherein the D/C field may occupy 1 bit, the CPT field may occupy 3 bits, each ack_sn field or each nack_sn field may occupy 12 bits, each E1 field, E2 field, or E3 field may occupy 1 bit, the R field may occur in 1 bit unit, the SO start field, the SO end field, or the NACK range may occur in 1 byte unit.

In connection with the structure shown in fig. 7, the receiver may inform the sender that data corresponding to the SN has been received through an ack_sn field. And, the receiving side can also inform the sending side that the data corresponding to the SN is not received through the NACK_SN field.

Sixth, the DAPS handoff procedure in the prior art.

In connection with fig. 3, fig. 8 illustrates a prior art DAPS handoff procedure. The DAPS switching procedure corresponds to the case that the DAPS switching fails and the RRC connection between the UE and the source gNB is normal in the embodiment shown in fig. 3, and specifically includes the following steps:

In the embodiment of the present application, the specific description of step S306 and step S307 may refer to the embodiment shown in fig. 3, and will not be repeated here.

If the handover fails and the RRC connection of the UE with the source gNB is normal, the following step S808 is performed:

in step S808, the UE may send failure information with SN of 0 to the source gNB. Accordingly, the source gNB may receive failure information from the UE with SN of 0.

In the prior art, after step S307 and before step S808, the UE re-establishes the RLC to return the RLC state to the initial state. Thus, after the UE re-establishes RLC, SN of failure information sent by the UE to the source gNB is 0.

However, in the case where the source gNB does not re-establish RLC, the reception window of the source gNB is likely not to include 0. Thus, the following step S809 is performed:

in step S809, the source gNB discards the failure information with SN of 0.

In step S809, since the source gNB discards the failure information with SN of 0, that is, the source gNB does not normally receive the failure information, the source gNB does not feed back a message for the source gNB to confirm that the failure information with SN of 0 is received to the UE. Further, if the UE does not receive feedback from the source gNB, the UE considers that the RRC connection with the source gNB is disconnected, and step S810 is performed:

in step S810, the UE may trigger an RRC reestablishment procedure.

Alternatively, the UE may start the timer when step S808 is performed, or at a time a certain length of time from the time when step S808 is performed. When the timer expires and the UE has not yet received the message for the source gNB to acknowledge receipt of failure information with SN of 0, step S810 may be performed.

In connection with the flowchart shown in fig. 8, in the case where the DAPS handover fails and the RRC connection of the UE and the source gNB is normal, since the UE re-establishes RLC, but the source gNB does not re-establish RLC, the source gNB cannot normally receive failure information from the UE. Further, the UE cannot receive a message for the source gNB to acknowledge receipt of the failure information, which may cause the UE to trigger the RRC reestablishment procedure. However, in case the DAPS handover fails and the RRC connection of the UE with the source gNB is normal, it is desirable for the UE to revert back to the source gNB for continued traffic transmission. Clearly, the prior art does not meet this desire. In addition, in the prior art, when the DAPS handover fails and the RRC connection between the UE and the source gNB is normal, the UE erroneously considers that the RRC connection with the source gNB is disconnected and reestablishes the RRC connection, and thus, the continuity of traffic transmission may be affected.

The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application. Wherein, in the description of the present application, "/" means that the related objects are in a "or" relationship, unless otherwise specified, for example, a/B may mean a or B; the term "and/or" in this application is merely an association relation describing an association object, and means that three kinds of relations may exist, for example, a and/or B may mean: there are three cases, a alone, a and B together, and B alone, wherein a, B may be singular or plural. Also, in the description of the present application, unless otherwise indicated, "a plurality" means two or more than two. "at least one of" or the like means any combination of these items, including any combination of single item(s) or plural items(s). For example, at least one (one) of a, b, or c may represent: a, b, c, a-b, a-c, b-c, or a-b-c, wherein a, b, c may be single or plural. In addition, in order to clearly describe the technical solutions of the embodiments of the present application, in the embodiments of the present application, the words "first", "second", and the like are used to distinguish the same item or similar items having substantially the same function and effect. It will be appreciated by those of skill in the art that the words "first," "second," and the like do not limit the amount and order of execution, and that the words "first," "second," and the like do not necessarily differ. Meanwhile, in the embodiments of the present application, words such as "exemplary" or "such as" are used to mean serving as examples, illustrations, or descriptions. Any embodiment or design described herein as "exemplary" or "for example" should not be construed as preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "such as" is intended to present related concepts in a concrete fashion that may be readily understood.

The embodiments of the present application may be applied to NR systems, and may also be applied to other new future-oriented systems, and the embodiments of the present application are not limited in particular.

As shown in fig. 9, a communication system 90 is provided in an embodiment of the present application. The communication system 90 comprises a first network device 901, a second network device 902 and a terminal device 903. Wherein a first link is used for communication between the terminal device 903 and the first network device 901 and a second link is used for communication between the terminal device 903 and the second network device 902. Typically, the terminal device 903 may communicate with the first network device 901 over a first link, or the terminal device 903 may communicate with the second network device 902 over a second link. When a link switch occurs, the terminal device 903 may communicate with the first network device 901 over a first link and simultaneously with the second network device 902 over a second link.

Wherein the terminal device 903 is configured to determine that a handover from the first link to the second link fails and the first link is in a connected state. The terminal device 903 is further configured to send the first indication information to the first network device 901. The first indication information is used to indicate that the terminal device 903 fails to switch from the first link to the second link, where SN of the first indication information is n+1, N is SN of a first signaling sent by the terminal device 903 to the first network device 901 before the terminal device 903 triggers switching from the first link to the second link, and N is a positive integer. A first network device 901 for receiving first indication information from a terminal device 903. In case the SN of the receive window of the first network device 901 comprises n+1, the first network device 901 is further configured to send a first message to the terminal device 903, the first message being configured to acknowledge receipt of the first indication information by the first network device 901. The terminal device 903 is further configured to receive the first message from the first network device 901, and send a second signaling with SN of 0 to the first network device 901. The specific implementation and technical effects of this scheme will be described in detail in the following method embodiments, and are not described here again.

Optionally, the first network device 901 or the second network device 902 in the embodiment of the present application is a device for accessing the terminal device 903 to a wireless network, which may be a base station (base station), an evolved NodeB (eNodeB), a transmitting and receiving point (transmission reception point, TRP), a gNB in a 5G mobile communication system, a base station in a future mobile communication system or an access node in a wireless-fidelity (Wi-Fi) system, and so on; the present invention may also be a module or unit that performs a function of a base station part, for example, a Central Unit (CU) or a Distributed Unit (DU). The embodiment of the application does not limit the specific technology and the specific device form adopted by the network device. In this application, network devices are referred to as radio access network devices unless otherwise specified.

Alternatively, the terminal device 903 in the embodiment of the present application may be a device for implementing a wireless communication function, such as a terminal or a chip or the like that can be used in the terminal. The terminal may be a UE, an access terminal, a terminal unit, a terminal station, a mobile station, a remote terminal, a mobile device, a wireless communication device, a terminal agent, a terminal apparatus, or the like in a 5G network or a public land mobile network (public land mobile network, PLMN) that evolves in the future. An access terminal may be a cellular telephone, cordless telephone, session initiation protocol (session initiation protocol, SIP) phone, wireless local loop (wireless local loop, WLL) station, personal digital assistant (personal digital assistant, PDA), handheld device with wireless communication capability, computing device or other processing device connected to a wireless modem, vehicle-mounted device or wearable device, virtual Reality (VR) terminal device, augmented reality (augmented reality, AR) terminal device, wireless terminal in industrial control (industrial control) or wireless terminal in self driving (self driving), wireless terminal in telemedicine (remote media), wireless terminal in smart grid (smart grid), wireless terminal in transportation security (transportation safety), wireless terminal in smart city (smart city), wireless terminal in smart home (smart home), etc. The terminal device 903 may be fixed in position or may be movable, which is not specifically limited in this embodiment of the present application.

Optionally, in the embodiment of the present application, the terminal device 903 includes a hardware layer, an operating system layer running above the hardware layer, and an application layer running above the operating system layer. The hardware layer includes hardware such as a central processing unit (central processing unit, CPU), a memory management unit (memory management unit, MMU), and a memory (also referred to as a main memory). The operating system may be any one or more computer operating systems that implement business processes through processes (processes), such as a Linux operating system, a Unix operating system, an Android operating system, an iOS operating system, or a windows operating system. The application layer comprises applications such as a browser, an address book, word processing software, instant messaging software and the like. Further, the embodiment of the present application is not particularly limited to the specific configuration of the execution body of the method provided in the embodiment of the present application, as long as communication can be performed by the method provided in the embodiment of the present application by running a program in which the code of the method provided in the embodiment of the present application is recorded. For example, the execution subject of the method provided in the embodiment of the present application may be the terminal device 903, or a functional module in the terminal device 903 capable of calling a program and executing the program; alternatively, the execution body of the method provided in the embodiment of the present application may be the first network device 901, or a functional module in the first network device 901 capable of calling a program and executing the program.

In other words, the related functions of the terminal device 903 or the first network device 901 in the embodiments of the present application may be implemented by one device, or may be implemented by multiple devices together, or may be implemented by one or more functional modules in one device, which is not specifically limited in the embodiments of the present application. It will be appreciated that the above described functionality may be either a network element in a hardware device, or a software functionality running on dedicated hardware, or a combination of hardware and software, or a virtualized functionality instantiated on a platform (e.g., a cloud platform).

Optionally, as shown in fig. 10, a schematic structural diagram of a first network device 901 and a terminal device 903 provided in an embodiment of the present application is shown.

Wherein the terminal device 903 comprises at least one processor 9031 and at least one transceiver 9033. Optionally, the terminal device 903 may also include at least one memory 9032, at least one output device 9034, or at least one input device 9035.

The processor 9031, the memory 9032, and the transceiver 9033 are connected by a communication line. The communication lines may include pathways that carry information between the components.

The processor 9031 may be a general purpose central processing unit (central processing unit, CPU), but may also be other general purpose processors, digital signal processors (digital signal processor, DSP), application specific integrated circuits (application specific integrated circuit, ASIC), field programmable gate arrays (field programmable gate array, FPGA) or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general purpose processor may be a microprocessor, but in the alternative, it may be any conventional processor. In a particular implementation, the processor 9031 may also include multiple CPUs, as one embodiment, and the processor 9031 may be a single core processor or a multi-core processor. A processor herein may refer to one or more devices, circuits, or processing cores for processing data.

The memory 9032 may be a device having a storage function. For example, but not limited to, a read-only memory (ROM) or other type of static storage device, random access memory (random access memory, RAM) or other type of dynamic storage device, which may store static information and instructions, a Programmable ROM (PROM), erasable PROM (EPROM), electrically erasable ROM (electrically erasable programmable read-only memory, EEPROM), compact disc (compact disc read-only memory, CD-ROM) or other optical disk storage, optical disk storage (including compact disc, laser disc, optical disc, digital versatile disc, blu-ray disc, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. The memory 9032 may be a stand alone device and may be connected to the processor 9031 via a communication line. The memory 9032 may also be integrated with the processor 9031.

The memory 9032 is used for storing computer-executable instructions for executing the embodiments of the present application, and the processor 9031 controls the execution. Specifically, the processor 9031 is configured to execute computer-executable instructions stored in the memory 9032, so as to implement the link switching method described in the embodiments of the present application.

Alternatively, in this embodiment of the present application, the processor 9031 may perform a function related to processing in a link switching method provided in the following embodiment of the present application, where the transceiver 9033 is responsible for communicating with other devices or a communication network, and this embodiment of the present application is not limited in particular.

Alternatively, the computer-executable instructions in the embodiments of the present application may be referred to as application program code or computer program code, which is not specifically limited in the embodiments of the present application.

The transceiver 9033 may use any transceiver-like device for communicating with other devices or communication networks, such as ethernet, radio access network (radio access network, RAN), or wireless local area network (wireless local area networks, WLAN), etc. The transceiver 9033 includes a transmitter (Tx) and a receiver (Rx).

The output device 9034 communicates with the processor 9031, and may display information in a variety of ways. For example, the output device 9034 may be a liquid crystal display (liquid crystal display, LCD), a light emitting diode (light emitting diode, LED) display device, a Cathode Ray Tube (CRT) display device, or a projector (projector), or the like.

The input device 9035 communicates with the processor 9031 to accept user input in a variety of ways. For example, the input device 9035 may be a mouse, a keyboard, a touch screen device, a sensing device, or the like.

The first network device 901 comprises at least one processor 9011, at least one transceiver 9013, and at least one network interface 9014. Optionally, the first network device 901 may further comprise at least one memory 9012. The processor 9011, the memory 9012, the transceiver 9013, and the network interface 9014 are connected through communication lines. The network interface 9014 is used to connect with a core network device through a link (e.g., S1 interface) or to connect with a network interface of another network device (not shown in fig. 10) through a wired or wireless link (e.g., X2 interface), which is not specifically limited in this embodiment of the present application. In addition, the description of the processor 9011, the memory 9012 and the transceiver 9013 may refer to the description of the processor 9031, the memory 9032 and the transceiver 9033 in the terminal device 903, and will not be repeated herein.

In connection with the schematic structural diagram of the terminal device 903 shown in fig. 10, fig. 11 is an exemplary specific structural form of the terminal device 903 provided in the embodiment of the present application.

Wherein in some embodiments the functionality of processor 9031 in fig. 10 may be implemented by processor 110 in fig. 11.

In some embodiments, the functionality of the transceiver 9033 in fig. 10 may be implemented by the antenna 1, the antenna 2, the mobile communication module 150, the wireless communication module 160, etc. in fig. 11. The mobile communication module 150 may provide a solution of wireless communication technologies including LTE, NR or future mobile communication applied on the terminal device 903. The wireless communication module 160 may provide solutions for wireless communication technologies including WLAN (e.g., wi-Fi network), bluetooth (BT), global navigation satellite system (global navigation satellite system, GNSS), frequency modulation (frequency modulation, FM), near field communication (near field communication, NFC), infrared, etc., applied on the terminal device 903. In some embodiments, antenna 1 of terminal device 903 is coupled to mobile communication module 150 and antenna 2 is coupled to wireless communication module 160 so that terminal device 903 can communicate with the network and other devices via wireless communication technology.

In some embodiments, the functionality of memory 9032 in fig. 10 may be implemented by internal memory 121 in fig. 11, or external memory to which external memory interface 120 is connected, or the like.

In some embodiments, the functionality of the output device 9034 of fig. 10 may be implemented through the display screen 194 of fig. 11.

In some embodiments, the functionality of the input device 9035 in fig. 10 may be implemented by a mouse, a keyboard, a touch screen device, or the sensor module 180 in fig. 11.

In some embodiments, as shown in fig. 11, the terminal device 903 may further include one or more of an audio module 170, a camera 193, keys 1132, a SIM card interface 195, a USB interface 130, a charge management module 140, a power management module 141, and a battery 142.

It is to be understood that the structure shown in fig. 11 does not constitute a specific limitation on the terminal device 903. For example, in other embodiments of the present application, the terminal device 903 may include more or less components than illustrated, or certain components may be combined, or certain components may be split, or different arrangements of components. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

The link switching method provided in the embodiments of the present application will be specifically described below with reference to fig. 1 to 11.

As shown in fig. 12, a link switching method provided in an embodiment of the present application includes the following steps:

Step S1201, the terminal device determines that the handover from the first link to the second link fails and the first link is in a connected state.

In connection with the communication system architecture shown in fig. 9, the first link is a link between the terminal device and the first network device, and the second link is a link between the terminal device and the second network device.

The "handoff" in embodiments of the present application may be a DAPS handoff, or other soft handoff, and embodiments of the present application are not limited in this regard.

Illustratively, the first network device in the embodiment of the present application may be a source gNB, and the second network device in the embodiment of the present application may be a target gNB.

Alternatively, before step S1201, step S306 and step S307 described above may be performed.

Step S1202, the terminal device sends first indication information with SN of n+1 to the first network device. Accordingly, the first network device receives first indication information with SN of n+1 from the terminal device.

The first indication information is used for indicating that the terminal equipment fails to switch from the first link to the second link, N is SN of a first signaling sent by the terminal equipment to the first network equipment before the terminal equipment triggers the switching from the first link to the second link, and N is a positive integer.

In the embodiment of the present application, after the terminal device sends the first signaling with SN being N to the first network device, RLC is not rebuilt, so SN of the first indication information sent by the terminal device to the first network device continues numbering, that is, SN of the first indication information is n+1.

The first indication information may be failure information, for example.

Step S1203, in case the SN of the receiving window of the first network device includes n+1, the first network device sends a first message to the terminal device. Accordingly, the terminal device receives the first message from the first network device.

The first message is used for the first network equipment to confirm that the first indication information is received.

In the embodiment of the present application, when the first network device does not reconstruct RLC, after receiving the first signaling with SN of N, the SN of the receiving window of the first network device includes n+1. At this time, the first network device can receive the first indication information with SN of n+1 without discarding the first indication information, and feed back the first message to the terminal device.

In step S1204, the terminal device sends a second signaling with SN of 0 to the first network device. Accordingly, the first network device receives the second signaling with SN of 0 from the terminal device.

Before step S1204, the terminal device may re-establish RLC. Thus, the SN of the second signaling sent by the terminal device is set to an initial state, i.e., the SN of the second signaling is 0.

Optionally, as shown in fig. 13, the link switching method provided in the embodiment of the present application further includes the following steps:

in step S1303, if the SN of the receiving window of the first network device does not include n+1, the first network device discards the first indication information.

Step S1304, in the case that the terminal device does not receive the first message from the first network device, the terminal device sends second indication information with SN of 0 to the first network device. Accordingly, the first network device receives the second indication information from the terminal device.

The second indication information is used for indicating the switching failure of the terminal equipment from the first link to the second link.

The second indication information may also be failure information, for example.

In step S1305, in the case where the SN of the receiving window of the first network device includes 0, the first network device sends a second message to the terminal device. Accordingly, the terminal device receives the second message from the first network device.

Wherein the second message is for the first network device to acknowledge receipt of the second indication information.

After receiving the second message, the terminal device may return to the first network device to continue transmission of signaling in step S1305, for example, the terminal device may send signaling with SN of 1 to the first network device.

The specific description of step S1201 and step S1202 in the embodiment shown in fig. 13 may be referred to the related description of the embodiment shown in fig. 12, and will not be repeated here.

Optionally, in conjunction with fig. 13, after step S1202 and before step S1304, the method provided by the embodiment of the present application further includes: the terminal device resends the first indication information to the first network device. In this scheme, the retransmission of the first indication information may exclude that the first network device does not normally receive the first indication information due to other reasons than that the SN of the receiving window of the first network device does not include n+1.

In the embodiment of the present application, the first indication information may be retransmitted multiple times. For example, the number of retransmissions of the first indication information may be set to be less than the number of retransmissions of the normal signaling, e.g. the first signaling or the second signaling.

Optionally, in combination with fig. 13, the link switching method provided in the embodiment of the present application further includes: the terminal equipment starts a timer with a timing duration of a first duration at a first moment; the first time is the time when the terminal equipment sends the first indication information, or the first time is the time which is a second time long from the time when the terminal equipment sends the first indication information after the time when the terminal equipment sends the first indication information; the terminal device not receiving the first message from the first network device, comprising: the terminal device still does not receive the first message from the first network device after the timer expires. In this scheme, the terminal device may set a timer, and trigger the transmission of the second indication information when the timer expires and the first message is not received.

Alternatively, in the case where SN of the receiving window of the first network device includes neither 0 nor n+1, the first network device discards the received first indication information and second indication information. Thus, the first network device does not send the first message or the second message to the terminal device. The terminal device may trigger the RRC reestablishment procedure if the terminal device does not receive the first message or the second message from the first network device. For example, the terminal device may trigger an RRC reestablishment procedure as shown in fig. 4. The terminal device in the embodiment of the present application may be the UE in fig. 4, and the first network device in the embodiment of the present application may be the last serving gNB in fig. 4.

Wherein the actions of the terminal device in the above embodiment may be called by the processor 9031 in the terminal device 903 shown in fig. 10 to instruct the terminal device to perform, or the actions of the terminal device in the above embodiment may be called by the processor 110 in the terminal device 903 shown in fig. 11 to instruct the terminal device to perform (including the internal memory 121 and/or the external memory 120); the actions of the first network device in the above embodiments may be invoked by the processor 9011 in the first network device 901 shown in fig. 10 to instruct the network device to execute application code stored in the memory 9012. The present embodiment is not limited in this regard.

It will be appreciated that in the various embodiments above, the methods and/or steps implemented by the terminal device may also be implemented by a component (e.g., a chip or circuit) usable with or comprising the terminal device; the methods and/or steps implemented by the first network device may also be implemented by a component (e.g., a chip or circuit) available to the first network device or by a device incorporating the first network device.

It will be appreciated that the terminal device or network device, in order to implement the above-described functions, includes corresponding hardware structures and/or software modules that perform the respective functions. Those of skill in the art will readily appreciate that the elements and algorithm steps of the examples described in connection with the embodiments disclosed herein may be implemented as hardware or combinations of hardware and computer software. Whether a function is implemented as hardware or computer software driven hardware depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

The embodiment of the application may divide the functional modules of the terminal device or the first network device according to the embodiment of the method, for example, each functional module may be divided corresponding to each function, or two or more functions may be integrated into one processing module. The integrated modules may be implemented in hardware or in software functional modules. It should be noted that, in the embodiment of the present application, the division of the modules is schematic, which is merely a logic function division, and other division manners may be implemented in actual implementation.

The terminal device or the first network device in the embodiment of the present application may be implemented in the form of the communication apparatus 1400 shown in fig. 14, for example. The communication device 1400 includes a transceiver module 1401. The transceiver module 1401 may be referred to as a transceiver unit, and may be, for example, a transceiver circuit, a transceiver, or a communication interface.

Taking the communication apparatus 1400 as an example of the terminal device in the above method embodiment, then: the communication device 1400 also includes a processing module 1402. A processing module 1402, configured to determine that a handover from a first link to a second link fails and the first link is in a connection state, where the first link is a link between the communication apparatus 1400 and a first network device, and the second link is a link between the communication apparatus 1400 and a second network device; a transceiver module 1401 configured to send first indication information to a first network device; the first indication information is used for indicating that the communication device 1400 fails to switch from the first link to the second link, the sequence number SN of the first indication information is n+1, N is SN of a first signaling sent to the first network device through the transceiver module 1401 before the communication device 1400 triggers the switch from the first link to the second link, and N is a positive integer; the transceiver module 1401 is further configured to send a second signaling to the first network device if the first message from the first network device is received; the first message is used for the first network equipment to confirm that the first indication information is received, and the SN of the second signaling is 0.

In a possible implementation manner, the transceiver module 1401 is further configured to send second indication information to the first network device and receive the second message from the first network device, where the first message from the first network device is not received; the second indication information is used to indicate that the communication apparatus 1400 fails to switch from the first link to the second link, SN of the second indication information is 0, and the second message is used by the first network device to acknowledge receipt of the second indication information.

In a possible implementation, the transceiver module 1401 is further configured to retransmit the first indication information to the first network device.

In a possible implementation manner, the processing module 1402 is further configured to start a timer with a timing duration of a first duration at a first time; the first time is the time when the transceiver module 1401 transmits the first indication information, or the first time is the time when the transceiver module 1401 transmits the first indication information, and then is a second time long from the time when the transceiver module 1401 transmits the first indication information; the transceiver module 1401 is further configured to not receive the first message from the first network device, and includes: for not yet receiving the first message from the first network device after the timer has expired.

Taking the communication apparatus 1400 as the first network device in the above method embodiment as an example, then: a transceiver module 1401, configured to receive first indication information from a terminal device; the first indication information is used for indicating that the handover of the terminal device from the first link to the second link fails, where the first link is a link between the terminal device and the communication apparatus 1400, the second link is a link between the terminal device and the second network device, a sequence number SN of the first indication information is n+1, N is SN of a first signaling sent by the terminal device to the communication apparatus 1400 before the terminal device triggers the handover from the first link to the second link, and N is a positive integer; the transceiver module 1401 is further configured to send a first message to the terminal device if SN of the receiving window of the communication apparatus 1400 includes n+1; wherein the first message is for the communication device 1400 to acknowledge receipt of the first indication information; the transceiver module 1401 is further configured to receive a second signaling from the terminal device, where SN of the second signaling is 0.

In one possible implementation, the communication device 1400 further includes: a processing module 1402; a processing module 1402, configured to discard the first indication information if the SN of the receiving window of the communication apparatus 1400 does not include n+1; the transceiver module 1401 is further configured to receive second indication information from the terminal device; the second indication information is used for indicating that the switching of the terminal equipment from the first link to the second link fails, and the SN of the second indication information is 0; the transceiver module 1401 is further configured to send a second message to the terminal device if SN of the receiving window of the communication apparatus 1400 includes 0; wherein the second message is for the communication device 1400 to acknowledge receipt of the second indication information.

All relevant contents of each step related to the above method embodiment may be cited to the functional description of the corresponding functional module, which is not described herein.

In the present embodiment, the communication apparatus 1400 is presented in a form in which respective functional modules are divided in an integrated manner. A "module" herein may refer to a particular ASIC, an electronic circuit, a processor and memory that execute one or more software or firmware programs, an integrated logic circuit, and/or other device that can provide the described functionality.

When the communication apparatus 1400 is a terminal device in the above-described method embodiment, in a simple embodiment, it will be appreciated by those skilled in the art that the communication apparatus 1400 may take the form of the terminal device 903 shown in fig. 10.

For example, the processor 9031 in the terminal device 903 shown in fig. 10 may cause the terminal device 903 to execute the link switching method in the above-described method embodiment by calling the computer-executed instructions stored in the memory 9032. Specifically, the functions/implementation procedure of the processing module 1402 in fig. 14 may be implemented by the processor 9031 in the terminal device 903 shown in fig. 10 calling computer-executable instructions stored in the memory 9032. The functions/implementation of the transceiver module 1401 in fig. 14 may be implemented by the transceiver 9033 shown in fig. 10.

Alternatively, when the communication apparatus 1400 is a terminal device in the above-described method embodiment, in a simple embodiment, one skilled in the art will recognize that the communication apparatus 1400 may take the form of the terminal device 903 shown in fig. 11.

For example, the processor 110 in the terminal device 903 shown in fig. 11 may cause the terminal device 903 to execute the link switching method in the above-described method embodiment by calling a computer-executable instruction stored in a memory (including the internal memory 120 or an external memory connected to the external memory interface 121). Specifically, the functions/implementation procedures of the transceiver module 1401 and the processing module 1402 in fig. 14 may be implemented by the processor 110 in the terminal device 903 shown in fig. 11 invoking computer-executed instructions stored in a memory. Alternatively, the function/implementation procedure of the processing module 1402 in fig. 14 may be implemented by the processor 110 in the terminal device 903 shown in fig. 11 calling computer-executable instructions stored in a memory, and the function/implementation procedure of the transceiver module 1401 in fig. 14 may be implemented by the wireless communication module 160 shown in fig. 11.

Alternatively, when the communication apparatus 1400 is the first network device in the above-described method embodiment, in a simple embodiment, those skilled in the art will recognize that the communication apparatus 1400 may take the form of the first network device 901 shown in fig. 10.

For example, the processor 9011 in the first network device 901 shown in fig. 10 may cause the first network device 901 to execute the link switching method in the above-described method embodiment by invoking computer-executed instructions stored in the memory 9012. In particular, the functions/implementations of the processing module 1402 in fig. 14 may be implemented by the processor 9011 in the first network device 901 shown in fig. 10 invoking computer-executable instructions stored in the memory 9012. The functions/implementation of the transceiver module 1401 in fig. 14 may be implemented by the transceiver 9013 shown in fig. 10.

Since the communication device 1400 provided in the present embodiment can perform the above-mentioned link switching method, the technical effects obtained by the method can be referred to the above-mentioned method embodiments, and will not be described herein.

It should be noted that one or more of the above modules or units may be implemented in software, hardware, or a combination of both. When any of the above modules or units are implemented in software, the software exists in the form of computer program instructions and is stored in a memory, a processor can be used to execute the program instructions and implement the above method flows. The processor may be built in a SoC (system on a chip) or ASIC, or may be a separate semiconductor chip. The processor may further include necessary hardware accelerators, such as field programmable gate arrays (field programmable gate array, FPGAs), PLDs (programmable logic devices), or logic circuits implementing dedicated logic operations, in addition to the cores for executing software instructions for operation or processing.

When the above modules or units are implemented in hardware, the hardware may be any one or any combination of a CPU, microprocessor, digital signal processing (digital signal processing, DSP) chip, micro control unit (microcontroller unit, MCU), artificial intelligence processor, ASIC, soC, FPGA, PLD, special purpose digital circuitry, hardware accelerator, or non-integrated discrete devices that may run the necessary software or that do not rely on software to perform the above method flows.

Optionally, an embodiment of the present application further provides a chip system, including: at least one processor and an interface, the at least one processor being coupled with the memory through the interface, the at least one processor, when executing the computer programs or instructions in the memory, causing the method of any of the method embodiments described above to be performed. In one possible implementation, the first device further comprises a memory. Alternatively, the chip system may be formed by a chip, or may include a chip and other discrete devices, which are not specifically limited in this embodiment of the present application.

In the above embodiments, it may be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using a software program, it may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions described in accordance with embodiments of the present application are produced in whole or in part. The computer may be a general purpose computer, a special purpose computer, a computer network, or other programmable apparatus. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center by a wired (e.g., coaxial cable, fiber optic, digital subscriber line (digital subscriber line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer readable storage medium may be any available medium that can be accessed by a computer or a data storage device including one or more servers, data centers, etc. that can be integrated with the medium. The usable medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a magnetic tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a Solid State Disk (SSD)), or the like.

Although the present application has been described herein in connection with various embodiments, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed application, from a review of the figures, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Although the present application has been described in connection with specific features and embodiments thereof, it will be apparent that various modifications and combinations can be made without departing from the spirit and scope of the application. Accordingly, the specification and drawings are merely exemplary illustrations of the present application as defined in the appended claims and are considered to cover any and all modifications, variations, combinations, or equivalents that fall within the scope of the present application. It will be apparent to those skilled in the art that various modifications and variations can be made in the present application without departing from the spirit or scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims and the equivalents thereof, the present application is intended to cover such modifications and variations.

Claims

1. A method for link switching, comprising:

the method comprises the steps that a terminal device determines that switching from a first link to a second link fails and the first link is in a connection state, wherein the first link is a link between the terminal device and a first network device, and the second link is a link between the terminal device and a second network device;

the terminal equipment sends first indication information to the first network equipment; the first indication information is used for indicating that the switching of the terminal equipment from the first link to the second link fails, the serial number SN of the first indication information is n+1, N is SN of a first signaling sent by the terminal equipment to the first network equipment before the terminal equipment triggers the switching from the first link to the second link, and N is a positive integer;

in the case that the terminal device receives a first message from the first network device, the terminal device sends a second signaling to the first network device; the first message is used for the first network device to confirm that the first indication information is received, and the SN of the second signaling is 0.

2. The method according to claim 1, wherein the method further comprises:

in the case that the terminal device does not receive the first message from the first network device, the terminal device sends second indication information to the first network device and receives a second message from the first network device; the second indication information is used for indicating that the terminal equipment fails to switch from the first link to the second link, the SN of the second indication information is 0, and the second message is used for the first network equipment to confirm that the second indication information is received.

3. The method of claim 2, wherein after the terminal device sends the first indication information to the first network device and before the terminal device sends the second indication information to the first network device, the method further comprises:

and the terminal equipment resends the first indication information to the first network equipment.

4. A method for link switching, comprising:

the method comprises the steps that first indication information from terminal equipment is received by first network equipment; the first indication information is used for indicating that the terminal equipment fails to switch from the first link to the second link, wherein the first link is a link between the terminal equipment and the first network equipment, the second link is a link between the terminal equipment and the second network equipment, the serial number SN of the first indication information is n+1, N is SN of a first signaling sent by the terminal equipment to the first network equipment before the terminal equipment triggers the switching from the first link to the second link, and N is a positive integer;

In the case that the SN of the receiving window of the first network device includes n+1, the first network device sends a first message to the terminal device; wherein the first message is used for the first network device to confirm that the first indication information is received;

the first network device receives a second signaling from the terminal device, and SN of the second signaling is 0.

5. The method according to claim 4, wherein the method further comprises:

discarding, by the first network device, the first indication information if the SN of the receive window of the first network device does not include n+1;

the first network equipment receives second indication information from the terminal equipment; the second indication information is used for indicating that the terminal equipment fails to switch from the first link to the second link, and the SN of the second indication information is 0;

in the case that the SN of the receiving window of the first network device includes 0, the first network device sends a second message to the terminal device; wherein the second message is used for the first network device to confirm that the second indication information is received.

6. A communication device, the communication device comprising: a transceiver module and a processing module;

the processing module is configured to determine that a handover from a first link to a second link fails and the first link is in a connection state, where the first link is a link between the communication device and a first network device, and the second link is a link between the communication device and a second network device;

the transceiver module is configured to send first indication information to the first network device; the first indication information is used for indicating that the communication device fails to switch from the first link to the second link, the serial number SN of the first indication information is n+1, N is SN of a first signaling sent to the first network device through the transceiver module before the communication device triggers the switching from the first link to the second link, and N is a positive integer;

the transceiver module is further configured to send a second signaling to the first network device when receiving a first message from the first network device; the first message is used for the first network device to confirm that the first indication information is received, and the SN of the second signaling is 0.

7. The communication apparatus of claim 6, wherein the transceiver module is further configured to send second indication information to the first network device and receive a second message from the first network device if the first message from the first network device is not received;

the second indication information is used for indicating that the communication device fails to switch from the first link to the second link, the SN of the second indication information is 0, and the second message is used for the first network equipment to confirm that the second indication information is received.

8. The communication apparatus of claim 7, wherein the transceiver module is further configured to retransmit the first indication information to the first network device.

9. A communication device, the communication device comprising: a transceiver module;

the receiving and transmitting module is used for receiving first indication information from the terminal equipment; the first indication information is used for indicating that the terminal equipment fails to switch from the first link to the second link, wherein the first link is a link between the terminal equipment and the communication device, the second link is a link between the terminal equipment and the second network equipment, a serial number SN of the first indication information is n+1, N is an SN of a first signaling sent by the terminal equipment to the communication device before the terminal equipment triggers the switching from the first link to the second link, and N is a positive integer;

The transceiver module is further configured to send a first message to the terminal device when SN of the receiving window of the communication device includes n+1; wherein the first message is used for the communication device to confirm that the first indication information is received;

the transceiver module is further configured to receive a second signaling from the terminal device, where SN of the second signaling is 0.

10. The communication apparatus according to claim 9, wherein the communication apparatus further comprises: a processing module;

the processing module is configured to discard the first indication information when SN of a receiving window of the communication device does not include n+1;

the receiving and transmitting module is further used for receiving second indication information from the terminal equipment; the second indication information is used for indicating that the terminal equipment fails to switch from the first link to the second link, and the SN of the second indication information is 0;

the transceiver module is further configured to send a second message to the terminal device if SN of the receiving window of the communication device includes 0; wherein the second message is used for the communication device to confirm that the second indication information is received.

11. A communication system, comprising: a second network device, a terminal device performing the method of any of claims 1-3, and a first network device performing the method of claim 4 or 5.

12. A communication device, comprising: a memory for storing a program and a processor coupled to the memory for executing the program stored by the memory; when the communication device is running, the processor runs the program to cause the communication device to perform the method of any one of the preceding claims 1-3; alternatively, the communication device is caused to perform the method of the preceding claim 4 or 5.

13. A computer readable storage medium, having stored thereon a computer program which, when executed by a computer, causes the computer to perform the method of any of claims 1-3; alternatively, the computer is caused to perform the method of claim 4 or 5.