CN111183675B

CN111183675B - Method and device for switching between systems

Info

Publication number: CN111183675B
Application number: CN201880064683.3A
Authority: CN
Inventors: 刘建华; 杨宁
Original assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Current assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Priority date: 2018-01-03
Filing date: 2018-05-22
Publication date: 2021-12-21
Anticipated expiration: 2038-05-22
Also published as: CN111183675A; WO2019134329A1; WO2019134329A8

Abstract

The application provides a method and a device for intersystem handover, wherein the method comprises the following steps: the method comprises the steps that network side equipment determines to trigger switching of UE from a first system to a second system; informing the UE to establish a second system session corresponding to the first system session in use by adopting a dual-pass mode; and executing the switching from the first system session to the corresponding second system session, and releasing the first system session. The method for keeping the session of the two systems before and after switching before the session switching between the systems can reduce the time delay generated when the UE is switched between the systems, and meet the requirement of high reliability.

Description

Method and device for switching between systems

Technical Field

The present application relates to the field of wireless communications technologies, and in particular, to a method and an apparatus for intersystem handover.

Background

With the rapid development of wireless network communication technology, wireless communication networks have gradually entered the 5G era. The 5G cellular network is mainly composed of three domains: 5GC (core network), NG-RAN (access network) and UE (user Equipment).

Here, the NG-RAN has a scenario in which the gNB (base station in 5G network) and the eNB (base station in 4G network) both access the CN of 5G, as shown in fig. 1. When the UE is in a connection state and needs to be switched from a 5G system to a 4G system, a base station of the NG-RAN sends a Handover Required message to an AMF (access mobility management function), so that intersystem switching is triggered.

However, currently, when performing an intersystem handover from 5G to 4G, a series of complex signaling interactions are required between the release of the 5G session and the completion of the establishment of the 4G session, which may cause a certain delay of the service. In addition, interruptions or data confusion during handover are inevitable. For some services that pursue high reliability, ultra-low latency, such a latency of several hundred milliseconds or even seconds is unacceptable.

Disclosure of Invention

In view of this, the present application provides a method and an apparatus for intersystem handover, so as to reduce a time delay generated when the UE performs the intersystem handover.

In a first aspect, the present application provides a method for intersystem handover, including:

the method comprises the steps that network side equipment determines to trigger switching of UE from a first system to a second system;

informing the UE to establish a second system session corresponding to the first system session in use by adopting a dual-pass mode;

and executing the switching from the first system session to the corresponding second system session, and releasing the first system session.

According to a specific embodiment of the present application, the method further comprises:

and determining whether MBB switching is executed aiming at the first system session according to the corresponding relation between the predetermined first system session identifier and whether MBB switching is executed, if so, executing the step of informing the UE to establish a second system session corresponding to the first system session in use by adopting a dual-pass mode.

According to a specific embodiment of the present application, the correspondence between the first system session identifier and whether to execute the MBB is determined by the first system core network side device according to the session characteristics of the first system session and a preset handover policy during the establishment/modification of the first system session.

According to a specific embodiment of the present application, the session features include: S-NSSAI and/or DNN.

According to a specific embodiment of the present application, when a first system session is established or modified, a first system core network side device sends an indication information for MBB for the first system session to a first system access network side device;

and the first system access network side equipment carries the indication information when initiating the switching from the first system to the second system.

According to a specific embodiment of the present application, after determining that the first system of the UE is triggered to switch to the second system, the first system core network side device sends a switching request message including preset identification information to the second system core network side device through an inter-system N26 interface;

and the second system core network side equipment prepares a second system session for the UE according to the preset identification information.

According to a specific embodiment of the present application, after determining that the first system of the UE is triggered to switch to the second system, the first system access network side device sends a switching request message including preset identification information to the second system core network side device through an inter-system N26 interface;

and the second core network side equipment prepares a second system session for the UE according to the preset identification information.

According to a specific embodiment of the present application, after the network side device determines to trigger the handover of the first system of the UE to the second system, the method further includes:

preparing for the UE for a second system session, the preparing comprising: mobility management and context mapping for session management.

According to a specific embodiment of the present application, the preparing further comprises: the second system session is assigned the same IP address as the corresponding first system session.

According to a specific embodiment of the present application, notifying the UE to establish the second system session corresponding to the first system session in use includes:

and sending a command containing preset identification information to the UE to indicate the UE to establish a second system session corresponding to the first system session in use by adopting a dual-pass mode.

and after receiving a connection request containing preset identification information sent by the UE, the second system core network side equipment establishes the second system session for the UE.

According to a specific embodiment of the present application, performing a handover from the first system session to a corresponding second system session, releasing the first system session includes:

and the second system core network side equipment switches the application data stream from the first system session to a corresponding second system session, and releases the first system session.

and after receiving the session release message sent by the UE, the first core network side equipment releases the first system session so as to switch the application data stream from the first system session to a corresponding second system session.

after the first system session is switched to the corresponding second system session, the second system core network side equipment sends a switching completion message to the unified data management equipment, and triggers the unified data management equipment to register the UE in the first system; alternatively, the first and second electrodes may be,

the first system core network side device sends a request to the unified data management device, and triggers the unified data management device to register the UE in the first system.

According to a specific embodiment of the present application, the handover complete message includes: a Location Update Location message containing the Initial attach parameter.

after receiving a registration request or a location updating request which is sent by the UE and carries dual-pass capability information, network side equipment determines whether the UE is allowed to use the dual-pass capability or not, and records a determination result;

and when the switching of the first system of the UE to the second system is determined to be triggered, and the UE is judged to have the bi-pass capability according to the record, continuing to execute the step of informing the UE to establish the second system session corresponding to the first system session in use.

and carrying the information of whether the UE is allowed to use the dual-communication capability in a registration response or a location updating response and returning the information to the UE.

According to a specific embodiment of the present application, before the handover is completed, data transmission between a network side device and the UE is performed on the first system session and the second system session simultaneously.

According to a specific embodiment of the present application, the first system is a 5G system, and the second system is a 4G system; alternatively, the first and second electrodes may be,

the second system is a 4G system, and the first system is a 5G system; alternatively, the first and second electrodes may be,

the first system and the second system are respectively different base station type systems under the same core network.

In a second aspect, the present application provides a registration method, including:

network side equipment receives a registration request or a location updating request sent by UE, wherein the registration request or the location updating request carries dual-communication capability information;

the dual-pass capability information indicates that the UE can establish a second system session corresponding to the first system session in use by adopting a dual-pass mode.

determining whether the UE is allowed to use dual-pass capability, and recording the determination result.

In a third aspect, the present application provides a method for intersystem handover, including:

after determining that the first system of the UE is triggered to switch to the second system, the first system access network side equipment sends a switching requirement message containing preset identification information to second system core network side equipment;

In a fourth aspect, the present application provides a method for intersystem handover, including:

the first system network side equipment sends a command containing preset identification information to the UE to indicate the UE to establish a second system session corresponding to the first system session in use by adopting a bi-pass mode.

According to a specific embodiment of the present application, the first system network side device includes:

and the first system core network side equipment or the first system access network side equipment.

According to a specific embodiment of the present application, the command including the preset identification information includes: NAS message or RRC reconfiguration message.

In a fifth aspect, the present application provides a method for intersystem handover, including:

after receiving the notification of the network side equipment, the UE adopts a bi-pass mode to establish a second system session corresponding to the first system session in use;

and after the switching from the first system session to the corresponding second system session is completed, switching back to the single-pass mode.

According to a specific embodiment of the present application, the receiving, by the UE, the notification from the network side device includes:

and the UE receives a command containing preset identification information sent by network side equipment.

According to a specific embodiment of the present application, the establishing a second system session corresponding to the first system session in use in the dual-pass mode includes:

and the UE sends a connection request containing preset identification information to second system core network side equipment so as to establish the second system session.

and the UE sends a session release message to first system core network side equipment so as to release the first system session and switch an application data stream from the first system session to a corresponding second system session.

According to a specific embodiment of the present application, before completing the handover, the method further includes:

and data transmission between the UE and the network side equipment is carried out on the first system session and the second system session simultaneously.

the second system is a 4G system, and the first system is a 5G system.

In a sixth aspect, the present application further provides a registration method, including:

UE sends a registration request or a location updating request to network side equipment, wherein the registration request or the location updating request carries dual-communication capability information;

and receiving a registration response or a location update response returned by the network side equipment, wherein the registration response or the location update response contains information about whether the network side equipment allows the UE to use the dual-communication capability.

In a seventh aspect, the present application provides a method for intersystem handover, where the method includes:

the method comprises the steps that UE receives a command which is sent by first system network side equipment and contains preset identification information;

a second system session corresponding to the first system session being used is established in a dual-pass mode.

In an eighth aspect, the present application provides an apparatus for intersystem handover, which is disposed on a network side, and includes:

a first determining unit, configured to determine to trigger handover of a UE from a first system to a second system;

a notification unit, configured to notify the UE to establish a second system session corresponding to the first system session in use in the dual-pass mode;

and the switching unit is used for executing switching from the first system session to the corresponding second system session and releasing the first system session.

According to a specific embodiment of the present application, the apparatus further comprises:

the decision unit is used for determining a corresponding relation between a predetermined first system session identifier and whether to execute a make-before-break MBB, and determining whether to execute MBB switching aiming at the first system session;

and the notification unit executes the process of notifying the UE to establish a second system session corresponding to the first system session in use by adopting a bi-pass mode when the decision result of the decision unit is yes.

According to a specific embodiment of the present application, an indication unit disposed in a first system core network side device is capable of sending, to a first system access network side device, indication information for performing an MBB for a first system session when the first system session is established or modified;

the first determining unit is disposed in the first system access network side device, and is further configured to carry the indication information when initiating a handover from the first system to the second system.

According to a specific embodiment of the present application, the first determining unit is disposed in a core network side device of a first system, and is further configured to send a handover request message including preset identification information to a core network side device of a second system through an inter-system N26 interface after determining that handover from the first system of the UE to the second system is triggered;

the device also includes: and the preparation unit is arranged at the core network side of the second system and used for preparing the second system session for the UE according to the preset identification information.

According to a specific embodiment of the present application, the first determining unit is disposed in the first system access network-side device, and is further configured to send a handover request message including preset identification information to the second system core network-side device through an inter-system N26 interface after determining that handover from the first system of the UE to the second system is triggered;

and the preparation unit is arranged on the second core network side device and used for preparing a second system session for the UE according to the preset identification information.

a preparation unit, configured to perform preparation of a second system session for the UE after the first determination unit determines that handover of the UE from the first system to the second system is triggered, where the preparation includes: mobility management and context mapping for session management.

According to a specific embodiment of the present application, the first determining unit is disposed at a first system access network side, and the first determining unit is further configured to send a handover request message including preset identification information to a second system core network side through an inter-system N26 interface;

the preparation unit is arranged at a core network side of a second system, and prepares a second system session for the UE according to the preset identification information.

According to a specific embodiment of the present application, the notification unit is specifically configured to send a command including preset identification information to the UE, so as to instruct the UE to establish a second system session corresponding to a first system session in use in a dual-pass mode.

According to a specific embodiment of the present application, the apparatus further comprises: and the establishing unit is arranged at a core network side of a second system and used for establishing the second system session for the UE after receiving the connection request which is sent by the UE and contains the preset identification information.

According to a specific embodiment of the present application, the switching unit is disposed at a core network side of the second system, and specifically performs:

and switching the application data stream from the first system session to the corresponding second system session, and releasing the first system session.

According to a specific embodiment of the present application, the switching unit includes a unit disposed at a second system core network side and a unit disposed at a first system core network side;

the unit is arranged at a core network side of a second system and used for informing the UE to switch the application data stream from the first system session to a corresponding second system session;

and after receiving a session release message sent by the UE, a unit arranged at a core network side of a first system releases the first system session so as to switch an application data stream from the first system session to a corresponding second system session.

a de-registration unit arranged at a core network side of a second system, configured to send a handover completion message to a unified data management device after the handover unit completes handover from the first system session to a corresponding second system session, and trigger the unified data management device to de-register the UE in the first system; alternatively, the first and second electrodes may be,

and the de-registration unit is arranged at the core network side of the first system and used for sending a request to the unified data management equipment and triggering the unified data management equipment to de-register the UE in the first system.

a transmission unit, configured to transmit data between a network side device and the UE simultaneously on the first system session and the second system session before the handover unit completes the handover.

In a ninth aspect, the present application provides a registration apparatus, disposed on a network side, the apparatus including:

a receiving unit, configured to receive a registration request or a location update request sent by a UE, where the registration request or the location update request carries dual-communication-capability information;

and the second determination unit is used for determining whether the UE is allowed to use the dual-pass capability or not and recording the determination result.

and the response unit is used for carrying the information of whether the UE is allowed to use the dual-communication capability in a registration response or a location update response and returning the information to the UE.

In a tenth aspect, the present application provides an apparatus for intersystem handover, the apparatus comprising:

a sending unit, configured to send a handover request message including preset identification information to a core network side of a second system after a first system access network side determines to trigger handover of a first system of a UE to the second system;

and the preparation unit is arranged at the core network side of the second system and used for preparing the second system session for the UE according to the preset identification information.

In an eleventh aspect, the present application provides an apparatus for intersystem handover, the apparatus comprising:

and the sending unit is arranged on the network side of the first system and used for sending a command containing preset identification information to the UE so as to indicate the UE to establish a second system session corresponding to the first system session in use by adopting a bi-pass mode.

According to a specific embodiment of the present application, the apparatus comprises:

and the establishing unit is arranged at a core network side of a second system and used for establishing the second system session for the UE after receiving the connection request which is sent by the UE and contains the preset identification information.

In a twelfth aspect, the present application further provides an inter-system handover apparatus, configured in a UE, where the apparatus includes:

a receiving unit, configured to receive a notification of a network-side device;

the establishing unit is used for establishing a second system session corresponding to the first system session in use by adopting a bi-pass mode after the receiving unit receives the notification of the network side equipment;

and the switching unit is used for switching back to the single-pass mode after the switching from the first system session to the corresponding second system session is completed.

According to an embodiment of the present application, the receiving unit specifically executes:

and receiving a command containing preset identification information sent by the network side equipment.

According to a specific embodiment of the present application, the establishing unit specifically executes:

and sending a connection request containing preset identification information to second system core network side equipment to establish the second system session.

According to a specific embodiment of the present application, the switching unit is further configured to send a session release message to a first system core network side device, so as to release the first system session and switch an application data stream from the first system session to a corresponding second system session.

a transmission unit, configured to transmit data between the UE and the network side device simultaneously on the first system session and the second system session before the handover unit completes the handover.

In a thirteenth aspect, the present application provides a registration apparatus, provided in a UE, including:

a sending unit, configured to send a registration request or a location update request to a network side device, where the registration request or the location update request carries dual-communication capability information;

a receiving unit, configured to receive a registration response or a location update response returned by the network-side device, where the registration response or the location update response includes information about whether the network-side device allows the UE to use dual-pass capability.

In a fourteenth aspect, the present application provides an apparatus for intersystem handover, the apparatus comprising:

the receiving unit is used for receiving a command which is sent by first system network side equipment and contains preset identification information;

the establishing unit is used for establishing a second system session corresponding to the first system session in use by adopting the dual-pass mode.

In a sixteenth aspect, the present application further provides an apparatus comprising

One or more processors;

a memory;

one or more programs, stored in the memory, for execution by the one or more processors to perform the operations of the above-described methods.

In a seventeenth aspect, the present application also provides a storage medium containing computer-executable instructions for performing the operations in the above-described method when executed by a computer processor.

According to the technical scheme, after determining that the UE is triggered to be switched from the first system to the second system, the network side equipment informs the UE to establish the second system session corresponding to the first system session in use by adopting a dual-pass mode, executes the switching from the first system session to the corresponding second system session, and releases the first system session. The method for keeping the session of the two systems before and after switching before the session switching between the systems can reduce the time delay generated when the UE is switched between the systems, and meet the requirement of high reliability.

Drawings

Fig. 1 is a schematic view of a scenario provided in an embodiment of the present application;

fig. 2 is a flowchart of a method for inter-system handover according to an embodiment of the present application;

fig. 3 is a flowchart of a system handover method according to a second embodiment of the present application;

fig. 4 is a flowchart of a method for network registration according to a third embodiment of the present application;

fig. 5a and fig. 5b are schematic diagrams of states of a UE in various stages according to an embodiment of the present application;

fig. 6 is a flowchart of a system component switching method according to a fourth embodiment of the present invention;

fig. 7 is a flowchart of a system handover method according to the fifth embodiment;

fig. 8 is a structural diagram of an inter-system handover apparatus disposed on a network side according to a sixth embodiment of the present application;

fig. 9 is a structural diagram of a registration apparatus disposed at a network side according to a seventh embodiment of the present application;

fig. 10 is a structural diagram of an inter-system handover apparatus disposed on a network side according to an eighth embodiment of the present application;

fig. 11 is a structural diagram of an inter-system handover apparatus disposed on a network side according to a ninth embodiment of the present application;

fig. 12 is a structural diagram of an inter-system handover apparatus installed in a UE according to a tenth embodiment of the present application;

fig. 13 is a structural diagram of a registration apparatus installed in a UE according to an eleventh embodiment of the present application;

fig. 14 is a block diagram of an inter-system handover apparatus installed in a UE according to a twelfth embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in detail below with reference to the accompanying drawings and specific embodiments.

The core idea of the application is that after determining to trigger the UE to switch from the first system to the second system, the network side notifies the UE to establish a second system session corresponding to the first system session in use in a dual-pass mode; and executing the switching from the first system session to the corresponding second system session, and releasing the first system session.

The method and the device can be used for realizing the switching between the two communication systems, for example, the switching from the 5G system to the 4G system is realized, and further, for example, the switching from the 4G system to the 5G system can be realized. In the following embodiments a handover from a 5G system to a 4G system is taken as an example. For another example, intersystem handover of different base station types under the same core network is realized, and in the following embodiments, handover is performed from the NR base station system to the LTE base station system under the 5G core network.

The first embodiment,

Fig. 2 is a flowchart of a method for inter-system handover according to an embodiment of the present application, and as shown in fig. 2, the method may include the following steps:

in 101, the 5G access network side device determines to trigger handover of the UE from the 5G system to the 4G system.

In 102, the 5G access network side device sends a Handover Required message to the 4G core network side device, where the Handover Required message carries preset identification information.

In this step, after the NG-RAN determines to trigger the Handover, a Handover Required message of preset identification information, for example, carrying a Make Before Break (Make Before Break) identification, may be sent to an AMF (access mobility management function) through an inter-system interface (N26 interface).

In 103, the 4G core network side device performs preparation of the 4G system session, where the preparation may include context mapping of mobility management and session management, and may also include IP address allocation of the 4G system session.

Specifically, after receiving a Handover Required message carrying a Make Before Break identifier, the AMF may send a Request (SM Context Request) for session management Context mapping to a PGW (public network gateway) of a 4G core network, and after completing Context mapping and IP address allocation for session management by the PGW, return a Response message (SM Context Response) to the AMF; then AMF sends a location Request to MME (mobile management entity), MME sends a Request for establishing Session (Create Session Request) to SGW (serving gateway), SGW returns a Response message (Create Session Response) to MME; MME sends a Handover Request (Handover Request) to E-UTRAN (4G access network side equipment), and the E-UTRAN returns a response message (Handover Request ack); the MME then returns a Relocation Response to the AMF. In the above process, a Data forwarding channel (Data forwarding channel) does not need to be established.

When performing context mapping for session management, the data filter, QoS parameter, and the like included in the second system session are made the same as those included in the corresponding first system session. That is, the data stream transmitted in the first system session can also be transmitted in the second session, and at the same time, the QoS guarantee can also be the same.

The IP address allocated by the PGW for the Session (PDN Connection) of the 4G system is the same as the IP address of the Session (PDU Session) of the corresponding 5G system. It should be noted that, if there is a PDU Session in the 5G system, a corresponding PDN Connection is established for the PDU Session, and the IP addresses of the two are the same. If the UE has multiple PDU sessions in use in the 5G system, a corresponding PDN Connection is established for each PDU Session, and the IP addresses of two corresponding sessions are the same.

In 104, the 4G core network side device sends a command containing the preset identification information to the UE.

In this step, the AMF may send a Command including the Make Before Break identifier to the UE, or the NG-RAN may send a Command including the Make Before Break identifier to the UE (in this case, the NG-RAN may be executed after receiving the Handover Command sent by the AMF). The command may be a NAS message or an RRC reconfiguration message.

In 105, the UE sends a connection request containing preset identification information to the 4G core network side device in the dual-active mode.

The UE is typically in a single-pass mode, i.e., a mode in which it uses or camps on only one communication system. And the UE receives a command containing the Mark Before Break identifier and learns that the 4G system session needs to be established in a bi-pass mode according to the Mark Before Break identifier. The UE may switch to the dual-active mode, and send a connection request containing the Make Before Break identifier to the MME, where the connection request may be an Attach (Attach) message or a Handover notification (Handover notify) message.

In the embodiment of the present invention, the Dual Registration (DR) refers to a mode that can be used or resident in two communication systems at the same time, and needs to be registered in the two communication systems.

In 106, the 4G core network side device establishes a 4G system session for the UE.

In this step, the MME may request the PGW to establish, for the UE, a PDN Connection corresponding to the PDU Session that the UE is using, according to the preparation made by the 4G core network. In addition, after identifying the Make Before Break identifier, the MME does not immediately release the PDU Session, but maintains the PDU Session and the PDN Connection at the same time.

In 107, the 4G core network side device performs a handover from the 5G system session to the corresponding 4G system session, releasing the 5G system session.

After establishing the PDN Connection, the PGW performs Path Switch, switches the application data stream from the PDU Session to the PDN Connection, and releases the PDU Session.

In addition, in order to achieve higher reliability, data transmission between the network side device and the UE may be performed on PDU Session and PDN Connection simultaneously. That is, the PGW performs duplicate transmission on the downlink data, and transmits the downlink data on the PDU Session while duplicating the same data on the PDN Connection. The UE also performs duplicate transmission on the uplink data, and copies the same data to transmit on the PDN Connection while transmitting the uplink data on the PDU Session.

In 108, the 4G core network side device performs de-registration of the UE in the 5G system.

In this step, after the PGW completes the Path Switch, the MME may be notified; the MME then sends a handover complete message, such as an Update location (Update location) message, containing the initial attach to a unified data management device, such as HSS/UDM

(Initial attach) parameter, triggering HSS/UDM to execute Cancel location message for 5G system.

In addition, after the PGW completes the Path Switch, the MME may be notified, and then the MME notifies the UE, so that the UE may Switch from the dual-pass mode back to the single-pass mode.

In this embodiment, the MBB handover policy may be configured in advance in a UDM (subscription information database) and/or a PCF (policy control network element) based on user granularity, or may be configured statically in advance in an SMF.

Wherein the MBB handover policy may be a policy that determines whether to perform MMB handover for the session based on preset session characteristics. Among other things, session features may include, but are not limited to: S-NSSAI (Single Network Slice Selection Assistance information, but Network Slice Selection Assistance information) and/or DNN.

For example, the configured policy may be as follows:

performing MBB switching when S-NSSAI-1 and DNN-1;

MBB switching is not executed during S-NSSAI-2 and DNN-1;

performing MBB switching when S-NSSAI-2 and DNN-3;

otherwise, MBB switching is not performed.

In this embodiment, when a 5G system session is established or modified, the SMF determines whether the 5G system session performs MBB handover according to a locally configured policy or a policy acquired from the UDM/PCF, and according to the policy and feature information of the 5G system session, and may store a correspondence between an ID of the 5G system session and whether the MBB handover is performed locally.

In the above flow, after the 5G system session is established or modified, the SMF may send the indication information that the 5G system session performs MBB Handover to the NG-RAN, and the NR-RAN performs step 102, that is, sends a Handover Required message carrying an MBB identifier to the 4G core network side device.

In addition, there is another implementation manner, in the above 102, the NR-RAN may send a Handover Required message in an existing manner, where the message does not carry the MBB identifier, but carries the ID information of the 5G system session. After receiving the Handover Required message, the AMF obtains information on whether to perform MBB Handover for the 5G system session from the SMF (for example, obtains information on whether to perform MBB Handover for the 5G system session, which is returned by the SMF, through an Nsf _ RDUSesion _ contextrssp message), and if so, the AMF continues to execute step 104.

It should be noted that the mechanism of the MBB strategy described above is also applicable in the subsequent embodiments.

Example II,

Fig. 3 is a flowchart of a system switching method according to a second embodiment, and an execution flow of the present embodiment is different from the first embodiment in the execution of switching and deregistration. As shown in fig. 3, the method may include the steps of:

steps 201 to 206 are the same as steps 101 to 106 in the first embodiment, and are not described again.

In 207, the 4G core network side device notifies the UE of completing the handover from the 5G system session to the corresponding 4G system session.

After the PDN Connection is established, the PGW notifies the MME, and the MME further notifies the UE to perform Path Switch (Path Switch).

In 208, the UE sends a release session message to the 5G core network side device.

The UE may notify the AMF to release the 5G system session through the NAS message.

In 209, the 5G core network side device releases the 5G system session.

And when the 5G core network side equipment releases the PDU Session, the application data flow is switched to the corresponding PDN Connection from the PDU Session. The UE may switch from the dual-pass mode back to the single-pass mode after completing the handover.

In 210, the 5G core network side device sends a request to a unified data management device (such as HSS/UDM), triggering the unified data management device to deregister with the UE in the 5G system.

In this step, while the AMF releases the 5G system session, or after, the AMF may send a Purge request to the HSS/UDM, and delete the registration information of the UE in the 5G system.

Example III,

Before the procedures described in the first and second embodiments, there is a procedure for registering the UE with the network, and the dual-pass capability of the UE may be registered in the procedure. As shown in fig. 4, the process may include the steps of:

in 301, the UE sends a registration request to the network side device, where the registration request carries the dual-pass capability information.

In the first embodiment and the second embodiment, when the UE registers with the 5G system, the Registration Request sent to the network side device of the 5G system may carry dual-pass capability information, where the dual-pass capability information indicates that the UE can establish a 4G system session corresponding to the 5G system session in use by using a dual-pass mode.

The Registration Request is sent by the UE to the NG-RAN, and may further be sent by the NG-RAN to the AMF.

In 302, the network side device determines whether the UE is allowed to use the dual-pass capability, and records the determination result.

In this step, the NG-RAN may determine whether the UE is allowed to use the dual-pass capability and record the determination result. In the first and second embodiments, the NG-RAN checks the record when determining to trigger the UE to switch from the 5G system to the 4G system, and if the UE is allowed to use the dual-pass capability, continues to execute according to the procedure in the first or second embodiment; otherwise, the handover may be performed according to an existing procedure or other procedures.

In 303, the network side device returns the determination result to the UE by carrying the determination result in a registration response.

In this step, the NG-RAN may include information on whether the user is allowed to use the dual-pass capability in the Registration Accept message and return to the UE.

In addition, in this embodiment, in addition to the registration request carrying the dual-pass capability information, the location update request may also be used to carry the dual-pass capability information of the UE; the network side device may include information on whether the user is allowed to use the dual-call capability in a location update response message and return the information to the UE.

As can be seen from the above embodiments, for the UE, a "Make Before Break" (Make Before Break) manner is adopted, and the mode can be as shown in fig. 5 a. Before switching, the system is in a single-pass mode, and 5G system conversation is adopted. And in the switching process, the dual-pass mode is set, and the 5G system session and the 4G system session are kept. And after the switching is finished, switching back to the single-pass mode, releasing the 5G system session and only adopting the 4G system session.

In the above embodiment, the example of switching from the 5G system to the 4G system is described, but the method provided by the present application is also applicable to switching from the 4G system to the 5G system, and the specific implementation process is similar, and the related devices of the 5G system and the devices of the 4G system may be exchanged.

Example four,

Fig. 6 is a flowchart of a system switching method according to a fourth embodiment of the present invention, and in this embodiment, an example is taken to switch from an NR base station system in a 5G core network to an LTE base station system. For the UE, the mode is as shown in fig. 5b, before the handover, in single-pass mode, the system session via the NR base station is adopted, and during the handover, in dual-pass mode, while the system session via the NR base station and the system session via the LTE base station are maintained. After the handover is completed, the handover is switched back to the single-pass mode, the system session via the NR base station is released, and only the system session via the LTE base station is adopted. As shown in fig. 6, the method may include the steps of:

in 601, the NR base station in the 5G core network determines to trigger the UE to switch from the NR base station system to the LTE base station system in the 5G core network.

In 602, the NR base station sends a Handover Required message to the 5G core network side device, where the Handover Required message carries preset identification information.

After the NR base station determines to trigger the Handover, a Handover Required message of preset identification information may be sent to the AMF through an inter-system interface (N26 interface), for example, the message carries a Make Before Break identifier.

In 603, the 5G core network side device sends a command containing the preset identification information to the UE.

In 604, the UE sends a connection request containing preset identification information to an LTE base station in the 5G core network in the dual-active mode.

The UE is usually in a single-pass mode, receives a command containing a Make Before Break identifier, learns that a session with a target system needs to be established in a dual-pass mode according to the Make Before Break identifier, and then may switch to the dual-pass mode, and send a connection request containing the Make Before Break identifier to an LTE base station under a 5G core network.

In 605, the LTE base station in the 5G core network sends a connection request including the preset identification information to the 5G core network side device.

In 606, the 5G core network side device establishes a system session via the LTE base station for the UE.

The LTE base station sends a connection request containing a Make Before Break identifier to the AMF, and the AMF can request the PGW to establish a second PDU Session corresponding to the first PDU Session in use for the UE. The first PDU Session is through the NR base station, the second PDU Session is through the LTE base station, and the two adopt different port numbers. In addition, after the AMF recognizes the Make Before Break flag, the first PDU Session is not released immediately, but the first PDU Session and the second PDU Session are maintained at the same time.

In 607, the 5G core network side device performs handover from the system session via the NR base station to the corresponding system session via the LTE base station, and releases the system session via the NR base station.

After establishing the second PDU Session, the PGW performs Path Switch, switches the application data stream from the first PDU Session to the second PDU Session, and releases the first PDU Session.

In addition, in order to achieve higher reliability, data transmission between the network side device and the UE may be performed on the first PDU Session and the second PDU Session at the same time. That is, the PGW performs duplicate transmission on the downlink data, and transmits the downlink data on the first PDU Session while duplicating the same data on the second PDU Session. The UE also performs duplicate transmission on the uplink data, and copies the same data to transmit on a second PDU Session while transmitting the uplink data on a first PDU Session.

In 608, the 5G core network side device performs de-registration of the UE in the LTE base station system.

In this step, after the PGW completes the Path Switch, the PGW may notify the AMF, and send a handover complete message, such as an Update location (Update location) message, to the unified data management device (such as HSS/UDM), where the Update location message includes an Initial attach parameter (Initial attach) parameter, so as to trigger the HSS/UDM to send a Cancel location message to the AMF.

In addition, after the PGW completes the Path Switch, the AMF may be notified, and then the UE is notified by the AMF, so that the UE may Switch from the dual-pass mode back to the single-pass mode.

Example V,

Fig. 7 is a flowchart of a system switching method provided in the fifth embodiment, and an execution flow of the present embodiment is different from the fourth embodiment in the processes of switching and deregistration. As shown in fig. 7, the method may include the steps of:

steps 701 to 706 are the same as steps 601 to 606 in the fourth embodiment, and are not described again.

In 707, the 5G core network side device informs the UE of the completion of the handover from the system session via the NR base station to the corresponding system session via the LTE base station.

After establishing the second PDU Session, the PGW notifies the AMF, and the AMF further notifies the UE to perform Path Switch (Path Switch).

In 708, the UE sends a release session message to the 5G core network side device.

The UE may notify the AMF to release the system session via the NR base station through the NAS message.

In 709, the 5G core network side device releases the system session via the NR base station.

And when the 5G core network side equipment releases the first PDU Session, the application data flow is switched from the first PDU Session to the corresponding second PDU Session. The UE may switch from the dual-pass mode back to the single-pass mode after completing the handover.

In 710, the 5G core network side device sends a request to a unified data management device (such as HSS/UDM), triggering the unified data management device to deregister with the NR base station system for the UE.

In this step, while the AMF releases the system session via the NR base station, or after, the AMF may send a Purge request to the HSS/UDM, and delete the registration information of the UE in the NR base station system.

The process of registering the dual-pass capability of the UE, which is applicable to the fourth and fifth embodiments, may refer to the third embodiment, and the basic implementation flows are the same, which are not described herein again.

The above is a description of the method provided in the present application, and the following is a description of the apparatus provided in the present application with reference to the embodiments.

Example six,

Fig. 8 is a structural diagram of an apparatus for inter-system handover provided at a network side according to a sixth embodiment of the present application, and as shown in fig. 8, the apparatus may include: a first determination unit 01, a notification unit 02, and a switching unit 03; the system can further comprise a preparation unit 04, a establishing unit 05 and a de-registration unit 06. The main functions of each component unit are as follows:

the first determination unit 01 is responsible for determining to trigger a handover of the UE from the first system to the second system.

The notification unit 02 is responsible for notifying the UE to establish a second system session corresponding to the first system session being used in the dual-pass mode.

The switching unit 03 is responsible for performing a switch from a first system session to a corresponding second system session, releasing the first system session.

The preparation unit 04 is responsible for, after the first determination unit 01 determines to trigger the handover of the UE from the first system to the second system, preparing a session of the second system for the UE, and the preparing includes: the preparing may further include: the second system session is assigned the same IP address as the corresponding first system session. It should be noted that, if there is one session in the first system, the UE establishes a corresponding second system session for the session, and the IP addresses of the two sessions are the same. If the UE has a plurality of sessions in use in the first system, corresponding second system sessions are respectively established for the sessions in use, and the IP addresses of the two corresponding sessions are the same.

The first determining unit 01 may be disposed at the first system access network side, and may be further configured to send a handover request message including preset identification information to the second system core network side through an inter-system interface (N26). The preparation unit 04 may be disposed at a core network side of the second system, and perform preparation of the second system session for the UE according to the preset identification information.

And a decision unit (not shown in the figure) for determining a correspondence between a predetermined first system session identifier and whether to execute a make-before-break MBB, and determining whether to execute an MBB handover for the first system session.

And when the decision result of the decision unit is yes, the notification unit 02 executes the process of notifying the UE to establish a second system session corresponding to the first system session in use in the dual-pass mode.

Wherein, the corresponding relation between the first system session identifier and whether to execute MBB is determined by the first system core network side device according to the session characteristics of the first system session and a preset switching policy in the process of establishing/modifying the first system session.

Wherein the session features include: S-NSSAI and/or DNN.

The apparatus may further include: an indication unit (not shown in the figure) disposed in the first system core network side device can send, when the first system session is established or modified, indication information for performing MBB on the first system session to the first system access network side device.

At this time, the first determining unit 01 may be disposed in the first system access network side device, and is further configured to carry the indication information when initiating a handover from the first system to the second system.

As an implementation manner, the first determining unit 01 is disposed in the first system access network-side device, and is further configured to send a handover request message including preset identification information to the second system core network-side device through an inter-system N26 interface after determining that handover of the first system of the UE to the second system is triggered; a preparation unit (not shown in the figure) disposed in the second core network side device, configured to prepare a second system session for the UE according to the preset identifier information.

As another embodiment, the first determining unit 01 may be disposed in the core network side device of the first system, and is further configured to send a handover request message including preset identification information to the core network side device of the second system through an inter-system N26 interface after determining that handover of the first system of the UE to the second system is triggered. At this time, the apparatus further includes: a preparation unit (not shown in the figure) disposed at the core network side of the second system, configured to prepare a second system session for the UE according to the preset identifier information.

Specifically, the notification unit 02 may send a command containing preset identification information to the UE to instruct the UE to establish the second system session corresponding to the first system session being used in the dual-pass mode.

The establishing unit 05 is disposed at the core network side of the second system, and is responsible for establishing a second system session for the UE after receiving a connection request containing the preset identification information sent by the UE.

The switching unit 03 may be disposed at the core network side of the second system, and specifically executes: and switching the application data stream from the first system session to the corresponding second system session, and releasing the first system session.

The switching unit 03 may also include a configuration unit, which is disposed on the first system core network side, and configured to release the first system session after receiving a session release message sent by the UE, so as to switch the application data stream from the first system session to a corresponding second system session.

The deregistration unit 06 disposed on the second system core network side, after the handover unit 03 completes the handover from the first system session to the corresponding second system session, sends a handover completion message, such as a Location Update Location message including an Initial attach parameter, to the unified data management device, and triggers the unified data management device to deregister the UE in the first system.

A de-registration unit 06, disposed on the first system core network side, is configured to send a request, such as a Purge request, to a unified data management device, and trigger the unified data management device to de-register the UE in the first system.

The apparatus may further include a transmission unit (not shown in the figure) configured to transmit data between the network-side device and the UE simultaneously on the first system session and the second system session before the handover unit 03 completes the handover. The data transmission between the network side device and the UE includes uplink data and downlink data, and the duplicate transmission is performed during data transmission.

The device can be used for realizing switching from a 5G system to a 4G system, namely, the first system can be the 5G system, and the second system is the 4G system. It can also be used to realize the switch from 4G system to 5G system, i.e. the second system is 4G system and the first system is 5G system.

Example seven,

Fig. 9 is a structural diagram of a registration apparatus disposed at a network side according to a seventh embodiment of the present application, and as shown in fig. 9, the apparatus includes: a receiving unit 11, a second determining unit 12 and a responding unit 13.

The receiving unit 11 is responsible for receiving a registration request or a location update request sent by the UE, where the registration request or the location update request carries dual-pass capability information; wherein the dual-pass capability information indicates that the UE is capable of establishing a second system session corresponding to the first system session in use using the dual-pass mode.

The second determination unit 12 is responsible for determining whether the UE is allowed to use the dual-pass capability and recording the determination result. The apparatus for intersystem handover shown in fig. 6 may check the record when determining to trigger the handover of the UE from the first system to the second system, and if the UE is allowed to use the dual-pass capability, the apparatus shown in fig. 6 continues to perform the handover; otherwise, the handover may be performed by an existing inter-system handover device or other inter-system handover devices.

The response unit 13 is responsible for carrying information on whether the UE is allowed to use the dual-pass capability in a registration response or a location update response and returning the information to the UE.

Example eight,

Fig. 10 is a structural diagram of an apparatus for inter-system handover provided at a network side according to an eighth embodiment of the present application, where the apparatus may include: a transmitting unit 21 and a preparation unit 22.

The sending unit 21 is responsible for sending a handover request message including preset identification information to the core network side of the second system after the first system access network side determines to trigger the handover of the first system of the UE to the second system.

The preparation unit 22 is disposed at the core network side of the second system and is responsible for preparing the second system session for the UE according to the preset identification information. The preparing may include context mapping for mobility management and session management, and may also include IP address assignment for the second system session.

And when the IP address is allocated, the second system session and the corresponding first system session adopt the same IP address.

Examples nine,

Fig. 11 is a structural diagram of an apparatus for inter-system handover provided at a network side according to a ninth embodiment of the present application, and as shown in fig. 11, the apparatus may include a sending unit 31 and may further include a establishing unit 32.

The sending unit 31 is disposed on the first system network side, and is responsible for sending a command including preset identification information to the UE to instruct the UE to establish a second system session corresponding to the first system session in use in the dual-pass mode.

The first system network side device may be a first system core network side device, or a first system access network side device.

The command including the preset identification information may include: NAS message or RRC reconfiguration message.

The establishing unit 32 is disposed at the core network side of the second system, and is responsible for establishing a second system session for the UE after receiving a connection request containing the preset identification information sent by the UE.

The division of the units in the above six, seven, eight and nine embodiments is only illustrative, and is a logical function division, and there may be other division ways in actual implementation. In addition, the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

Examples ten,

Fig. 12 is a structural diagram of an apparatus for inter-system handover provided to a UE according to a tenth embodiment of the present application, and as shown in fig. 12, the apparatus may include: a receiving unit 41, a establishing unit 42 and a switching unit 43. The main functions of each component unit are as follows:

the receiving unit 41 is responsible for receiving the notification of the network-side device. Specifically, the receiving unit 41 receives a command containing preset identification information sent by the network side device.

The establishing unit 42 is responsible for establishing the second system session corresponding to the first system session in use in the dual-pass mode after the receiving unit 41 receives the notification of the network-side device. Specifically, a connection request including the preset identification information may be sent to the core network side device of the second system, so as to establish the second system session.

The switching unit 43 is responsible for switching back to the single-pass mode after the switching from the first system session to the corresponding second system session is completed.

The handover from the first system session to the corresponding second system session may be performed by the network side, or may be performed by the UE. When executed by the UE, the switching unit 43 is further configured to send a release session message to the first system core network side device, so as to release the first system session and switch the application data stream from the first system session to the corresponding second system session.

In addition, the apparatus may further include a transmission unit (not shown in the figure) configured to perform data transmission between the UE and the network-side device on the first system session and the second system session simultaneously before the handover unit 43 completes the handover. The data transmission between the network side device and the UE includes uplink data and downlink data, and the duplicate transmission is performed during data transmission.

Examples eleven,

Fig. 13 is a structural diagram of a registration apparatus provided in a UE according to an eleventh embodiment of the present application, and as shown in fig. 13, the apparatus may include a transmitting unit 51, and may further include a receiving unit 52.

The sending unit 51 is responsible for sending a registration request or a location update request to the network side device, where the registration request or the location update request carries dual-communication capability information. Wherein the dual-pass capability information indicates that the UE is capable of establishing a second system session corresponding to the first system session in use using the dual-pass mode.

The receiving unit 52 is responsible for receiving a registration response or a location update response returned by the network-side device, where the registration response or the location update response includes information about whether the network-side device allows the UE to use the dual-pass capability.

Examples twelve,

Fig. 14 is a block diagram of an apparatus for inter-system handover provided to a UE according to a twelfth embodiment of the present invention, and as shown in fig. 14, the apparatus may include: a receiving unit 61 and a establishing unit 62. The main functions of each component unit are as follows:

the receiving unit 61 is responsible for receiving a command containing preset identification information sent by a first system network side device.

The establishing unit 62 is responsible for establishing a second system session corresponding to the first system session being used in the dual-pass mode.

The command containing the preset identification information may adopt NAS messages or RRC reconfiguration messages.

Specifically, the establishing unit 62 may send a connection request including preset identification information to the second system core network side device, so as to establish the second system session.

The division of the units in the above eight, nine and ten embodiments is only illustrative, and is a logical function division, and there may be another division manner in actual implementation. In addition, the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, the method and apparatus provided in the embodiments of the present application may be implemented in one or more integrated circuits, for example, a codec chip, or may be implemented by a program to instruct related hardware, where the program may be stored in a computer-readable storage medium. Each unit in the above embodiments may be implemented in the form of hardware, or may also be implemented in the form of a software functional module. This application is not limited to any specific form of hardware or software combination.

For example, may be implemented by an apparatus comprising:

one or more processors;

a memory;

one or more programs, stored in the memory, that are executed by the one or more processors to perform operations comprising:

As another example, execution by the one or more processors results in:

network side equipment receives a registration request sent by UE, wherein the registration request carries dual-communication capability information;

As another example, execution by the one or more processors results in:

UE sends a registration request to network side equipment, wherein the registration request carries dual-communication capability information;

As another example, execution by the one or more processors results in:

In addition, with the development of time and technology, the meaning of the medium is more and more extensive, and the propagation path of the program is not limited to a tangible medium any more, and can be directly downloaded from a network and the like. Any combination of one or more computer-readable media may be employed. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated data signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may also be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.

The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A method for intersystem handover, the method comprising:

the method comprises the steps that network side equipment determines to trigger switching of UE from a first system to a second system, wherein the network side equipment comprises first system core network side equipment or first system access network side equipment;

performing a handoff from the first system session to a corresponding second system session, releasing the first system session;

after determining to trigger the switching of the UE from the first system to the second system, the network side equipment sends a switching requirement message containing a make-before-break identifier to the core network side equipment of the second system through an inter-system N26 interface;

and the second system core network side equipment performs second system session preparation aiming at the UE according to the make-before-break identifier, wherein a data forwarding channel is not established, the preparation comprises mobility management, context mapping of session management and allocation of an IP address which is the same as that of the corresponding first system session for the second system session.

2. The method of claim 1, further comprising:

3. The method according to claim 2, wherein the correspondence between the first system session identifier and whether to execute MBB is determined by the first system core network side device according to the session characteristics of the first system session and a preset handover policy during the first system session establishment/modification process.

4. The method of claim 3, the session features comprising: S-NSSAI and/or DNN.

5. The method according to claim 3, wherein the first system core network side device sends the indication information of MBB for the first system session to the first system access network side device when the first system session is established or modified;

6. The method of claim 1, wherein notifying the UE to establish a second system session corresponding to the first system session being used comprises:

and sending a command containing a make-before-break identifier to the UE to instruct the UE to establish a second system session corresponding to the first system session in use by adopting a dual-pass mode.

7. The method of claim 1, further comprising:

and after receiving a connection request containing a make-before-break identifier sent by the UE, the second system core network side equipment establishes the second system session for the UE.

8. The method of claim 1, wherein performing a handoff from the first system session to a corresponding second system session, wherein releasing the first system session comprises:

9. The method of claim 1, wherein performing a handoff from the first system session to a corresponding second system session, wherein releasing the first system session comprises:

10. The method of claim 8, further comprising:

11. The method of claim 10, wherein the handover complete message comprises: a Location Update Location message containing the Initial attach parameter.

12. The method of claim 1, further comprising:

13. The method of claim 12, further comprising:

14. The method of claim 1, wherein data transmission between a network side device and the UE is performed on the first system session and the second system session simultaneously before the handover is completed.

15. The method of any one of claims 1 to 14, wherein the first system is a 5G system and the second system is a 4G system; alternatively, the first and second electrodes may be,

the second system is a 5G system, and the first system is a 4G system; alternatively, the first and second electrodes may be,

16. A method for intersystem handover, the method comprising:

after determining that the first system of the UE is triggered to switch to the second system, the first system access network side equipment sends a switching request message containing a make-before-break identifier to the second system core network side equipment through an inter-system N26 interface;

17. A method for intersystem handover, the method comprising:

a first system network side device sends a command containing a make-before-break identifier to a UE through an intersystem N26 interface to instruct the UE to establish a second system session corresponding to a first system session in use by adopting a dual-pass mode, wherein the first system network side device comprises a first system core network side device or a first system access network side device;

and after receiving a connection request containing a make-before-break identifier sent by the UE, second system core network side equipment establishes a second system session for the UE, wherein the second system core network side equipment prepares the second system session for the UE according to the make-before-break identifier, wherein a data forwarding channel is not established, and the preparation comprises mobility management, context mapping of session management and allocation of an IP address which is the same as that of the corresponding first system session for the second system session.

18. The method of claim 17, wherein the command including a make-before-break flag comprises: NAS message or RRC reconfiguration message.

19. A method for intersystem handover, the method comprising:

after receiving the notification of the network side equipment, the UE establishes a second system session corresponding to the first system session in use by adopting a bi-pass mode, wherein the network side equipment comprises first system core network side equipment or first system access network side equipment;

switching back to the single-pass mode after the switching from the first system session to the corresponding second system session is completed;

wherein the UE receiving the notification of the network side device includes:

the UE receives a command containing a make-before-break identifier sent by network side equipment;

wherein the establishing of the second system session corresponding to the first system session in use in the dual-pass mode comprises:

the UE sends a connection request containing a make-before-break identifier to second system core network side equipment to establish the second system session, wherein the second system core network side equipment prepares the second system session aiming at the UE according to the make-before-break identifier, wherein a data forwarding channel is not established, and the preparation comprises mobility management, context mapping of session management and allocation of an IP address which is the same as that of the corresponding first system session to the second system session.

20. The method of claim 19, further comprising:

21. The method of claim 19, wherein prior to completing the handover, the method further comprises:

22. The method of any one of claims 19 to 21, wherein the first system is a 5G system and the second system is a 4G system; alternatively, the first and second electrodes may be,

the second system is a 5G system, and the first system is a 4G system.

23. A method for intersystem handover, the method comprising:

the method comprises the steps that UE receives a command containing a make-before-break identifier sent by first system network side equipment, wherein the first system network side equipment comprises first system core network side equipment or first system access network side equipment;

establishing a second system session corresponding to the first system session in use by adopting a bi-pass mode;

24. The method of claim 23, wherein the command including a make-before-break flag comprises: NAS message or RRC reconfiguration message.

25. An intersystem handover apparatus, disposed on a network side, the apparatus comprising:

a switching unit, configured to perform switching from the first system session to a corresponding second system session, and release the first system session;

the first determining unit is arranged in the first system core network side device or the first system access network side device, and is further configured to determine that the first system triggering the UE switches to the second system, and send a switching request message including a make-before-break identifier to the second system core network side device through an inter-system N26 interface;

the device further comprises: and the preparation unit is arranged at the core network side of the second system and used for preparing a second system session for the UE according to the make-before-break identifier, wherein a data forwarding channel is not established, and the preparation comprises mobility management, context mapping of session management and allocation of an IP address which is the same as that of the corresponding first system session for the second system session.

26. The apparatus of claim 25, further comprising:

27. The apparatus according to claim 26, wherein the correspondence between the first system session identifier and whether to execute MBB is determined by the first system core network side device according to the session characteristics of the first system session and a preset handover policy during the first system session establishment/modification process.

28. The apparatus of claim 27, wherein the session features comprise: S-NSSAI and/or DNN.

29. The apparatus according to claim 27, wherein the indication unit disposed in the first system core network side device is capable of sending, to the first system access network side device, indication information for MBB performed on the first system session when the first system session is established or modified;

30. The apparatus of claim 25, wherein the notifying unit is specifically configured to send a command including a make-before-break flag to the UE to instruct the UE to establish the second system session corresponding to the first system session in use in the dual-pass mode.

31. The apparatus of claim 25, further comprising: and the establishing unit is arranged at the core network side of a second system and used for establishing the second system session for the UE after receiving the connection request which is sent by the UE and contains the make-before-break identifier.

32. The apparatus of claim 25, wherein the handover unit is disposed at a core network side of a second system, and specifically performs:

and switching the application data stream from the first system session to a corresponding second system session, and releasing the first system session.

33. The apparatus of claim 25, wherein the handover unit is disposed at a core network side of the first system, and specifically performs:

and after receiving a session release message sent by the UE, releasing the first system session so as to switch the application data stream from the first system session to a corresponding second system session.

34. The apparatus of claim 32, further comprising:

35. The apparatus of claim 34, wherein the handover complete message comprises: a Location Update Location message containing the Initial attach parameter.

36. The apparatus of claim 25, further comprising:

37. The apparatus of any one of claims 25 to 36, wherein the first system is a 5G system and the second system is a 4G system; alternatively, the first and second electrodes may be,

38. An apparatus for inter-system handover, the apparatus comprising:

a sending unit, configured to send a handover request message including a make-before-break identifier to a core network side of a second system through an inter-system N26 interface after a first system access network side determines to trigger handover of a first system of the UE to the second system;

and the preparation unit is arranged on the core network side of the second system and used for preparing a second system session for the UE according to the make-before-break identifier, wherein a data forwarding channel is not established, the preparation comprises the context mapping of mobility management and session management and the allocation of an IP address which is the same as that of the corresponding first system session for the second system session.

39. An apparatus for inter-system handover, the apparatus comprising:

a sending unit, configured to send a command including a make-before-break identifier to a UE through an inter-system N26 interface, so as to instruct the UE to establish a second system session corresponding to a first system session in use in a dual-pass mode, where the first system network side device includes a first system core network side device or a first system access network side device;

wherein the apparatus further comprises:

and the establishing unit is arranged at a core network side of a second system and used for establishing the second system session for the UE after receiving a connection request which is sent by the UE and contains a make-before-break identifier, wherein the core network side equipment of the second system prepares the second system session for the UE according to the make-before-break identifier, a data forwarding channel is not established, and the preparation comprises mobility management, context mapping of session management and allocation of an IP address which is the same as that of a corresponding first system session for the second system session.

40. The apparatus of claim 39, wherein the command including a make-before-break flag comprises: NAS message or RRC reconfiguration message.

41. An apparatus for intersystem handover, configured in a UE, the apparatus comprising:

a receiving unit, configured to receive a notification of a network-side device, where the network-side device includes a first system core network-side device or a first system access network-side device;

the switching unit is used for switching back to the single-pass mode after the switching from the first system session to the corresponding second system session is completed;

wherein the receiving unit specifically executes:

receiving a command containing a make-before-break identifier sent by network side equipment;

wherein the establishing unit specifically executes:

and sending a connection request containing a pre-make-before-break identifier to second system core network side equipment to establish the second system session, wherein the second system core network side equipment prepares the second system session for the UE according to the pre-make-before-break identifier, wherein a data forwarding channel is not established, and the preparation comprises mobility management, context mapping of session management and allocation of an IP address which is the same as that of the corresponding first system session to the second system session.

42. The apparatus of claim 41, wherein the switching unit is further configured to send a release session message to a first system core network side device, so as to release the first system session and switch the application data stream from the first system session to a corresponding second system session.

43. The apparatus of claim 41, further comprising:

44. An apparatus for inter-system handover, the apparatus comprising:

a receiving unit, configured to receive a command including a make-before-break identifier sent by a first system network-side device, where the first system network-side device includes a first system core network-side device or a first system access network-side device;

the system comprises an establishing unit, a receiving unit and a sending unit, wherein the establishing unit is used for establishing a second system session corresponding to a first system session in use by adopting a dual-pass mode;

wherein the establishing unit specifically executes:

and sending a connection request containing a make-before-break identifier to second system core network side equipment to establish the second system session, wherein the second system core network side equipment prepares the second system session for the UE according to the make-before-break identifier, wherein a data forwarding channel is not established, and the preparation comprises mobility management, context mapping of session management and allocation of an IP address which is the same as that of the corresponding first system session to the second system session.

45. The apparatus of claim 44, wherein the command including a make-before-break flag comprises: NAS message or RRC reconfiguration message.

46. An apparatus comprising

A plurality of processors;

a memory;

a plurality of programs, stored in the memory, for execution by the plurality of processors for performing operations in a method as claimed in any one of claims 1 to 24.

47. A storage medium containing computer-executable instructions for performing operations in the method of any one of claims 1 to 24 when executed by a computer processor.