CN112312495B - Method for supporting switching in mobile communication network - Google Patents

Abstract

A method for UE handover, comprising: and the destination base station receives a third message from a core network element connected with the destination base station, wherein the third message carries UE identification information for identifying the UE.

Description

Method for supporting switching in mobile communication network

Technical Field

The present invention relates to the field of mobile communication technology, and in particular, to a method for supporting handover in a mobile communication network.

Background

In a 5G communication system, a network element includes: different kinds of User Equipment (UE), access node (gNB), access and mobility management function (AMF), session Management Function (SMF), and data plane function (UPF). Wherein, AMF, SMF and UPF belong to core network element.

In an Evolved packet system (Evolved PACKET SYSTEM, EPS) communication system, a network element includes: different kinds of UE, access node (eNB), mobility Management Entity (MME), serving Gateway (SGW), packet data network gateway (PGW), etc. Wherein, MME, SGW and PGW belong to core network elements.

The UE may be handed over in the same communication system or between different communication systems. For example, the UE may handoff between access nodes of a 5G communication system, i.e., intra-system handoff; the UE may also be handed over between an access node of the 5G communication system and an access node of the EPS communication system, i.e. an Inter-system handover (Inter-system handover).

Fig. 1 is a schematic diagram of a system architecture when a UE is handed over.

The UE is handed over from a source access node, i.e. access node 1 connected to the core network 1, to a target access node, i.e. access node 2 connected to the core network 2.

Fig. 2 is a schematic diagram of a UE simultaneously establishing a wireless connection with two access nodes.

When the UE is in a dual connectivity state, i.e., the UE establishes a wireless connection with one access node while simultaneously establishing a wireless connection with another access node. Wherein one access Node is a Master Node (Master Node) connected to the UE through a control plane shown in solid lines and a user plane shown in dotted lines; the other access Node is a Secondary Node (SN), which may be connected to the UE only through the user plane. Two access nodes may be connected to the core network of the same communication system, e.g. both access nodes may be gnbs connected to the 5G core network; the two access nodes may also be connected to core networks of different communication systems, e.g. the two access nodes may be respectively a gNB connected to the core network of the 5G communication system and an eNB connected to the core network of the EPS communication system.

For the UE in the dual connectivity state, the following two scenarios may occur when it performs handover:

(1) Before a handover occurs, the UE is in dual connectivity while connected to one primary node 1 and one secondary node 0. After switching, the UE is connected with only one access node, wherein the access node is an auxiliary node 0 before switching;

(2) Before a handover occurs, the UE is in a dual connectivity state while connected to one primary node 1 and one secondary node 0; after the handover occurs, the UE is still in dual connectivity while connected to one primary node 2, and the secondary node 0.

The two scenarios have in common that the UE's connection with the auxiliary node 0 remains unchanged before and after the handover. If downlink data has been transmitted to the secondary node 0 before handover is completed but not yet transmitted to the UE, and the downlink data will still be transmitted to the UE through the secondary node 0 after handover, the secondary node 0 will forward the downlink data in the existing scheme, but the data forwarding is unnecessary because the destination node of forwarding is still the secondary node 0. In order to avoid the above unnecessary data forwarding, it is required that the secondary node 0 can recognize that the UE currently being switched has downlink data transmitted to the secondary node 0 after the handover.

However, in existing mechanisms, some handover-related signaling does not include information that allows the access node after the handover to identify the UE currently being handed over. Therefore, unnecessary forwarding of the downstream data may occur, thereby causing waste of network resources and increasing delay in downstream data transmission.

Further, in the above scenario (2), for the UE that is in dual connectivity before and after the handover and the secondary node 0 remains unchanged, in order for the primary node 2 after the handover to be able to configure the secondary node correctly, the primary node 1 before the handover needs to be able to notify the primary node 2 after the handover of information about the secondary node 0, so that the primary node 2 can determine whether the secondary node can be kept unchanged as a secondary node after the handover according to the information.

However, in existing mechanisms, some handover-related signaling does not include identification information of the secondary node. Therefore, the auxiliary node 0 before the handover may not be maintained after the handover is completed, and thus the above-described unnecessary forwarding may not be avoided.

Still further, in the above scenario (2), on the premise that the primary node 2 determines that the secondary node 0 remains unchanged after the handover, the UE context existing on the secondary node 0 should be reserved after the handover is completed.

However, in existing mechanisms, some handover-related signaling does not include information about the secondary node 0 that remains unchanged after the handover. Therefore, it may occur that data about the UE at the secondary node 0 is deleted erroneously or unnecessarily.

Still further, in the secondary node addition preparation process, a trigger scenario of the secondary node addition preparation process is indicated by the master node, and the trigger scenario may include a secondary node change (SN change), intra-eNB HO, inter-eNB HO, NGRAN intra-node handover (intra-NGRAN HO), NGRAN inter-node handover (inter-NGRAN HO), eNB-to-NGRAN node handover (eNB-NGRAN HO), and NGRAN node-to-eNB handover (NGRAN-eNB HO).

However, in the existing mechanism, the secondary node addition preparation procedure trigger scenario of the EPS communication system includes only secondary node change, intra-eNB handover, and inter-eNB handover; the 5G communication system has not defined an explicit secondary node addition preparation procedure trigger scenario. It can be seen that there are some secondary nodes that are not explicitly defined to add a preparation procedure trigger scenario.

Disclosure of Invention

In view of one or more of the problems set forth above, the present invention provides a method of supporting handover in a mobile communication network.

According to an embodiment of the present disclosure, there is provided a method for UE handover, wherein a source base station sends a first message to a core network element connected to the source base station, where the first message carries UE identification information for identifying the UE.

Optionally, the first message carries auxiliary base station identification information for identifying the auxiliary base station.

Optionally, the first message carries a source base station identifier for identifying the source base station, and/or a source cell identifier for identifying a source cell, and/or a measurement result of the UE.

Optionally, the first message is a base station and core network interface application protocol signaling handover request message.

Optionally, the method further comprises: and the source base station receives an eighth message from the core network element connected with the source base station, wherein the eighth message carries a field for indicating whether the context of the UE existing on the auxiliary base station is reserved after switching.

Optionally, the method further comprises: the source base station receives an eighth message from the core network element connected with the source base station, wherein the eighth message carries UE identification information for identifying the UE, and/or an auxiliary base station identification for identifying an auxiliary base station, and/or a destination base station identification for identifying a destination base station.

Optionally, the eighth message is a base station and core network interface application protocol signaling handover command message.

Optionally, the field for indicating whether the UE context existing on the secondary base station is reserved after handover is a UE context hold indication field.

Optionally, the UE identification information is a UE identification allocated to the UE by the secondary node.

Optionally, the UE identity is SgNB UE X AP ID, or S-NG-RAN node UE XnAP ID.

Optionally, when the UE identification information is a cell radio network temporary identifier (Cell Radio Network Tempory Identity-value, C-RNTI) allocated to the UE by the secondary node, the first message further carries a primary and secondary cell identifier of the UE at the secondary node and/or secondary base station identifier information.

Optionally, the carrying may be carried directly by the message, or may be carried by a sub-field carried by a source-to-destination transparent container field carried by the message.

Optionally, the subfield is a source NG-RAN node to destination NG-RAN node transparent container field or a source eNB to destination eNB transparent container field.

Optionally, the carrying may be carried directly by the message, or may be carried by a sub-field carried by a destination-to-source transparent container field carried by the message.

Optionally, the subfield is a destination NG-RAN node to source NG-RAN node transparent container field or a destination eNB to source eNB transparent container field.

According to an embodiment of the present disclosure, there is provided an apparatus for UE handover, which performs the above method.

According to an embodiment of the present disclosure, there is provided a computer device for a user equipment UE, including a memory, and a processor, where the memory stores instructions that when executed by the processor implement the above method.

According to an embodiment of the present disclosure, there is provided a method for UE handover, including: and the destination base station receives a third message from a core network element connected with the destination base station, wherein the third message carries UE identification information for identifying the UE.

Optionally, the third message carries auxiliary base station identification information for identifying the auxiliary base station.

Optionally, the third message carries a source base station identifier for identifying the source base station, and/or a source cell identifier for identifying a source cell, and/or a measurement result of the UE.

Optionally, the third message is a base station and core network interface application protocol signaling handover request message

Optionally, the method further comprises: the destination base station sends a fourth message to the auxiliary base station, wherein the fourth message carries the UE identification information and/or a field for indicating a trigger scene of the current auxiliary node adding preparation process; the destination base station receives a fifth message from the secondary base station.

Optionally, the method further comprises: the destination base station sends a fourth message to the source base station, wherein the fourth message carries the UE identification information and/or a source cell identification for identifying the source cell; and the destination base station receives a fifth message from the source base station, wherein the fifth message carries the UE identification information.

Optionally, the fourth message is an inter-base station interface application protocol signaling secondary node addition request message SGNB ADDITION REQUEST or S-NODE ADDITION REQUEST.

Optionally, the fifth message is an inter-base station interface application protocol signaling secondary node addition request acknowledgement message SGNB ADDITION REQUEST ACKNOWLEDGE or S-NODE ADDITION REQUEST ACKNOWLEDGE.

Optionally, the field used for indicating the trigger scenario of the current secondary node addition preparation procedure is an inter-base station interface application protocol signaling secondary base station addition trigger indication field SGNB Addition Trigger Indication, and the SGNB Addition Trigger Indication field value is one of SN change, inter-eNB HO, intra-eNB HO, inter-NGRAN HO, intra-NGRAN HO, eNB-NGRAN HO, NGRAN-eNB HO.

Optionally, the field used for indicating the trigger scenario of the current secondary node adding preparation procedure is an inter-base station interface application protocol signaling secondary base station adding trigger indication field S-NODE Addition Trigger Indication, and the value of the S-NODE Addition Trigger Indication field is one of SN change, inter-eNB HO, intra-eNB HO, inter-NGRAN HO, intra-NGRAN HO, eNB-NGRAN HO, NGRAN-eNB HO.

Optionally, the method further comprises: and the target base station sends a sixth message to a core network element connected with the target base station, wherein the sixth message carries a field for indicating whether the context of the UE existing on the auxiliary base station is reserved after switching.

Optionally, the method further comprises: and the target base station sends a sixth message to a core network element connected with the target base station, wherein the sixth message carries the UE identification information, and/or an auxiliary base station identification for identifying an auxiliary base station, and/or a target base station identification for identifying the target base station.

Optionally, the sixth message is a base station and core network interface application protocol signaling handover request acknowledgement message.

Optionally, the field for indicating whether the UE context existing on the secondary base station is reserved after handover is a UE context hold indication field.

Optionally, the UE identification information is a UE identification allocated to the UE by the secondary node.

Optionally, the UE identity is SgNB UE X AP ID, or S-NG-RAN node UE XnAP ID.

Optionally, when the UE identification information is a cell RNTI allocated to the UE by the secondary node, the third message further carries a primary and secondary cell identification of the UE at the secondary node and/or secondary base station identification information

Optionally, the carrying may be carried directly by the message, or may be carried by a sub-field carried by a source-to-destination transparent container field carried by the message.

Optionally, the subfield is a source NG-RAN node to destination NG-RAN node transparent container field or a source eNB to destination eNB transparent container field.

Optionally, the carrying may be carried directly by the message, or may be carried by a sub-field carried by a destination-to-source transparent container field carried by the message.

Optionally, the subfield is a destination NG-RAN node to source NG-RAN node transparent container field or a destination eNB to source eNB transparent container field.

According to an embodiment of the present disclosure, there is provided an apparatus for UE handover, which performs the above method.

According to an embodiment of the present disclosure, there is provided a computer device for a user equipment UE, including a memory, and a processor, where the memory stores instructions that when executed by the processor implement the above method.

According to an embodiment of the present disclosure, there is provided a method for UE handover, including: the secondary base station receives a fourth message from the first main base station, wherein the fourth message carries UE identification information for identifying the UE and/or a field for indicating a trigger scene of a current secondary node adding preparation process; and the auxiliary base station sends a fifth message to the first main base station.

Optionally, the fourth message is an inter-base station interface application protocol signaling secondary node addition request message SGNB ADDITION REQUEST or S-NODE ADDITION REQUEST.

Optionally, the fifth message is an inter-base station interface application protocol signaling secondary node addition request acknowledgement message SGNB ADDITION REQUEST ACKNOWLEDGE or S-NODE ADDITION REQUEST ACKNOWLEDGE.

Optionally, the field used for indicating the trigger scenario of the current secondary node addition preparation procedure is an inter-base station interface application protocol signaling secondary base station addition trigger indication field SGNB Addition Trigger Indication, and the SGNB Addition Trigger Indication field value is one of SN change, inter-eNB HO, intra-eNB HO, inter-NGRAN HO, intra-NGRAN HO, eNB-NGRAN HO, NGRAN-eNB HO.

Optionally, the field used for indicating the trigger scenario of the current secondary node adding preparation procedure is an inter-base station interface application protocol signaling secondary base station adding trigger indication field S-NODE Addition Trigger Indication, and the value of the S-NODE Addition Trigger Indication field is one of SN change, inter-eNB HO, intra-eNB HO, inter-NGRAN HO, intra-NGRAN HO, eNB-NGRAN HO, NGRAN-eNB HO.

Optionally, the UE identification information is a UE identification allocated to the UE by the secondary node.

Optionally, the UE identity is SgNB UE X AP ID, or S-NG-RAN node UE XnAP ID.

Optionally, when the UE identification information is a cell RNTI allocated to the UE by the secondary node, the fourth message further carries a primary cell identification and/or a secondary cell identification information of the UE at the secondary node.

According to an embodiment of the present disclosure, there is provided an apparatus for UE handover, which performs the above method.

According to an embodiment of the present disclosure, there is provided a computer device for a user equipment UE, including a memory, and a processor, where the memory stores instructions that when executed by the processor implement the above method.

Drawings

These and/or other aspects, features and advantages of the present invention will become more apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, wherein:

Fig. 1 shows a schematic diagram of a system architecture when a UE is handed over;

Fig. 2 shows a schematic diagram of a UE in a dual connectivity state;

FIG. 3 illustrates a handover method;

Fig. 4 shows a specific example of applying the handover method shown in fig. 3 to an intra-system handover scenario of a 5G communication system;

Fig. 5 shows a handover method;

Fig. 6 shows a specific example of applying the handover method shown in fig. 5 to an intersystem handover scenario from EPS to 5G communication systems;

FIG. 7 illustrates a handover method;

Fig. 8 shows a specific example of applying the handover method shown in fig. 7 to an intra-system handover scenario of a 5G communication system;

fig. 9 shows a handover method;

fig. 10 shows a specific example of applying the handover method shown in fig. 9 to an intra-system handover scenario in an EPS communication system;

fig. 11 shows a specific example of applying the handover method shown in fig. 9 to an intersystem handover scenario from EPS to 5G communication systems;

fig. 12 shows a specific example of applying the handover method shown in fig. 9 to an intersystem handover scenario from 5G to EPS communication systems;

Fig. 13 shows a specific example of applying the handover method shown in fig. 9 to a handover scenario within a 5G communication system.

Fig. 14 shows a specific example of applying the handover method shown in fig. 5 to an intersystem handover scenario from 5G to EPS communication systems.

Detailed Description

The present application provides a method for supporting handover in a mobile communication network. In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail below by referring to the accompanying drawings and examples.

The expressions "first", "second", "third", etc. in the present description are for the purpose of distinction only and are not limiting.

In the following embodiments, a communication architecture is shown in which a UE is connected to a core network element through an access node. In an embodiment, the access node takes the gNB and the eNB as examples; the core network element is exemplified by an AMF and an MME providing mobility management functions.

In the following embodiments, the following interface protocols are involved: x2 application protocol (X2 AP), xn application protocol (XnAP), NG application protocol (NGAP), and S1 application protocol (S1 AP). It should be noted that, although the embodiment of the present invention is described by taking X2 and Xn as examples of the lateral interfaces between two base stations, the method of the present invention is also applicable to the case where other interfaces are between two base stations; although the embodiments of the present invention are described by taking NG and S1 as examples of interfaces between the base station and the core network, the method of the present invention is also applicable to the case where other interfaces between the base station and the core network are used. That is, in the present specification, X2 APs and XnAP are examples of inter-base station interface application protocols, and NGAP and S1AP are examples of base station and core network interface application protocols.

Fig. 3 is a schematic view of the first embodiment. The first embodiment describes a handover method.

In a first embodiment, a handover method includes the steps of:

Step 301: the first node sends a first message to the third node, wherein the first message carries UE identification information.

Step 302: and the third node sends a third message to the second node, wherein the third message carries the UE identification information in the first message.

Fig. 4 is a schematic view of a second embodiment. The second embodiment is a specific example of applying the handover method in the first embodiment to an intra-system handover scenario in a 5G communication system.

In the second embodiment, before performing intra-5G system handover, the UE is in a dual-connection state while connected to the primary node gNB1 and the secondary node gNB 0; after making an intra-5G system handover, the UE is in a connection only to gNB 0. It can be seen that, in the second embodiment, gNB1 is the source node, gNB0 is the destination node, and the destination node is the auxiliary node before handover. Wherein, the source node gNB1 and the destination node gNB0 are both connected to the same core network element AMF.

The source node gNB 1 may correspond to the first node in embodiment one, the destination node gNB 0 may correspond to the second node in embodiment one, and the AMF may correspond to the third node in embodiment one.

In the above 5G communication system intra-system handover scenario, the handover method includes the following steps:

Step 401: the source node gNB 1 sends a first message to the AMF, which may be a handover required (HANDOVER REQUIRED) message. The handover required message may be HANDOVER REQUIRED messages in NGAP signalling in this implementation. And the HANDOVER REQUIRED message carries the UE identification information.

Specifically, the HANDOVER REQUIRED message carries a Source to destination transparent Container (Source to TARGET TRANSPARENT Container) field, the Source to TARGET TRANSPARENT Container field may carry a Source NG-RAN node to destination NG-RAN node transparent Container (Source NG-RAN Node to Target NG-RAN Node Transparent Container) field, and the Source NG-RAN Node to Target NG-RAN Node Transparent Container field may carry UE identification information. Alternatively, the HANDOVER REQUIRED message may directly contain a cell for indicating UE identification information to directly carry the UE identification information.

Specifically, the UE identification information may be a UE identification S-NG-RAN node UE XnAP ID allocated by the secondary node gNB 0 to the UE on the Xn interface. Alternatively, when the UE identification information is a cell radio network temporary identifier (Cell Radio Network Tempory Identity-value, C-RNTI) allocated to the UE by the secondary node gNB 0, the HANDOVER REQUIRED message further carries a primary secondary cell identifier (Primary Secondary Cell ID, PScell ID) of the UE at the secondary node gNB 0, or the secondary node gNB 0 identification information.

Step 402: the AMF sends a third message, which may be a HANDOVER REQUEST message, to the destination node gNB 0. The HANDOVER REQUEST message may be a HANDOVER REQUEST message in NGAP signaling in this embodiment, where the HANDOVER REQUEST message carries the UE identification information in the HANDOVER REQUIRED message.

Specifically, the AMF transparently forwards the received content of the Source to TARGET TRANSPARENT content field to the destination node gNB 0. Alternatively, if in step 401 the UE identification information is directly carried by the HANDOVER REQUIRED message, the HANDOVER REQUEST message should also directly carry the UE identification information.

In the above step, when the UE identity information is a C-RNTI, the message carrying the UE identity information further carries PScell ID of the UE at the auxiliary node gNB 0 or the auxiliary node gNB 0 identity information.

The above-described approach may be advantageous. Specifically, for the downlink data of the UE that has been transmitted to the destination node gNB 0 before the handover is completed but has not yet been transmitted to the UE, since the destination node gNB 0 is treated as a secondary node before the handover, the destination node gNB 0 can find the context of the UE that has been established on the destination node gNB 0 according to the UE identification information. When the UE identifier is C-RNTI, the destination base station finds the context of the UE in gNB 0 according to the received PScell ID of the UE in the auxiliary node gNB 0 and/or the auxiliary node identifier information of gNB 0 and the UE identifier C-RNTI. The destination node gNB 0 does not need to forward data before and after switching as in the existing mechanism.

Step 403: the destination node gNB 0 sends a sixth message to the AMF, which may be a handover request confirm (HANDOVER REQUEST ACKNOWLEDGE) message, which in this implementation may be a HANDOVER REQUEST ACKNOWLEDGE message in NGAP signaling.

Step 404: the AMF sends an eighth message, which may be a HANDOVER COMMAND (HANDOVER COMMAND) message, which in this implementation may be a HANDOVER COMMAND message in NGAP signaling, to the source node gNB 1.

Fig. 5 is a schematic view of a third embodiment. The third embodiment describes a handover method.

In a third embodiment, a handover method includes the steps of:

step 501: the first node sends a first message to the third node, wherein the first message carries UE identification information.

Step 502: and the third node sends a second message to the fourth node, wherein the second message carries the UE identification information in the first message.

Step 503: and the fourth node sends a third message to the second node, wherein the switching request message carries the UE identification information in the second message.

Fig. 6 is a schematic view of a fourth embodiment. The fourth embodiment is a specific example of applying the handover method in the third embodiment to an intersystem handover scenario from EPS to 5G communication systems.

In the fourth embodiment, before performing an intersystem handover, the UE is in a dual-connection state while connected to the master node eNB1 and the auxiliary node gNB 0; after an intersystem handover, the UE is connected only to gNB 0. In the fourth embodiment, the eNB1 is a source node, the gNB 0 is a destination node, and the destination node is a secondary node before handover. Wherein the source node eNB1 is connected to an MME and the destination node gNB 0 is connected to an AMF.

The source node eNB 1 may correspond to the first node in embodiment three, the destination node gNB 0 may correspond to the second node in embodiment three, the MME may correspond to the third node in embodiment three, and the AMF may correspond to the fourth node in embodiment three.

In the above handover scenario between EPS and 5G communication systems, the handover method includes the following steps:

Step 601: the source node eNB 1 sends a first message to the MME, which may be a handover required message, which in this implementation may be a HANDOVER REQUIRED message in S1AP signaling. The HANDOVER REQUIRED message carries UE identification information and/or secondary base station identification information.

Specifically, the HANDOVER REQUIRED message carries a Source to TARGET TRANSPARENT content field, and when the target base station is an NG-RAN node, the Source to TARGET TRANSPARENT content field may carry a Source NG-RAN Node to Target NG-RAN Node Transparent Container field, and the Source NG-RAN Node to Target NG-RAN Node Transparent Container field carries UE identification information and/or secondary base station identification information. Alternatively, the HANDOVER REQUIRED message may directly carry UE identification information and/or secondary base station identification information.

Specifically, the UE identification information may be a UE identification SgNB UE X AP ID allocated by the secondary node gNB 0 to the UE on the X2 interface. Alternatively, the UE identification information may be an identification C-RNTI allocated to the UE by the secondary node gNB 0, and when the UE identification information is the C-RNTI, the HANDOVER REQUIRED message also needs to include the secondary node identification information of the UE at PScell ID of the secondary node gNB 0 and/or gNB 0.

Step 602: the MME sends a second message to the AMF, where the second message may be a forwarding reset request (FORWARD RELOCATION REQUEST) message, where the forwarding reset request message may be a FORWARD RELOCATION REQUEST message in a GPRS tunneling protocol (GPRS Tunnelling Protocol, GTP) control plane protocol signaling in this embodiment, and the FORWARD RELOCATION REQUEST message carries the UE identification message and/or secondary base station identification information in the HANDOVER REQUIRED message.

Specifically, the MME transparently forwards the content of the Source to TARGET TRANSPARENT Container field received by the MME to the AMF. Alternatively, in step 601, if the UE identity information and/or secondary base station identity information is directly carried by the HANDOVER REQUIRED message, the GTP control plane protocol signaling should also directly carry the UE identity information and/or secondary base station identity information.

Step 603: the AMF sends a third message to the destination node gNB 0, where the third message may be a HANDOVER REQUEST message, where the HANDOVER REQUEST message in this embodiment may be a HANDOVER REQUEST message in NGAP signaling, where the HANDOVER REQUEST message carries the UE identification message and/or auxiliary base station identification information in the HANDOVER REQUIRED message.

Specifically, the AMF transparently forwards the received content of the Source to TARGET TRANSPARENT content field to the destination node gNB 0. Alternatively, in step 602, if the GTP control plane protocol signaling directly carries the UE identification information and/or secondary base station identification information, the HANDOVER REQUEST message should also directly carry the UE identification information and/or secondary base station identification information.

In the above step, when the UE identity information is a C-RNTI, the message carrying the UE identity information further carries PScell ID of the UE at the auxiliary node gNB 0 or the auxiliary node gNB 0 identity information.

The above-described approach may be advantageous. Specifically, for the downlink data of the UE that has been transmitted to the destination node gNB 0 before the handover is completed but has not yet been transmitted to the UE, since the destination node gNB 0 is treated as a secondary node before the handover, the destination node gNB 0 may find the context of the UE that has been established on the destination node gNB 0 according to the UE identification information and/or the secondary base station identification, and the destination node gNB 0 does not need to forward the data before and after the handover as in the existing mechanism. The destination node gNB 0 may find the context of the UE that has been established on the destination node gNB 0 based on the UE identification information and/or the secondary base station identification, thereby knowing the bearers (e.g., bearers terminated at the secondary node or secondary cell group (Secondary Cell Group, SCG) bearers) that have been configured on the secondary base station prior to the handover. For a bearer already configured on the secondary base station before handover (e.g., a bearer terminated at the secondary node, or an SCG bearer), data forwarding inside the base station is performed without the need for forwarding data from the source base station to the destination base station as in the existing handover mechanism. When the UE identifier is C-RNTI, the destination base station finds the context of the UE in gNB 0 according to the received PScell ID of the UE in the auxiliary node gNB 0 and/or the auxiliary node identifier information of gNB 0 and the UE identifier C-RNTI.

If gNB0 supports a control plane and user plane separated architecture, gNB0 includes a gNB centralized unit control plane unit (gNB-CU-CP) and a gNB centralized unit user plane unit (gNB-CU-UP). The gNB0-CU-CP requests the gNB0-CU-UP to allocate channel information corresponding to each evolved radio access bearer E-RAB. The channel information includes a transport layer address and a channel identification. The gNB0-CU-UP allocates channel information for data forwarding for each E-RAB requested and sends the channel information to the gNB0-CU-CP. And corresponding to the bearer terminated at the gNB 0at the source end, the gNB0-CU-CP does not need to request gNB0-CU-UP to allocate channel information for the E-RAB. And the gNB0-CU-CP can find the UE context according to the received UE identification message and/or auxiliary base station identification information. The gNB0-CU-CP knows the bearer terminating at the gNB0-CU-UP at the source according to the UE context. The identity of gNB0-CU-CP is the same as the secondary base station identity of gNB 0.

Step 604: the target gNB 0 sends a sixth message to the AMF, which may be a handover request confirm message, which in this embodiment may be HANDOVER REQUEST ACKNOWLEDGE messages in NGAP signaling. For the bearer for performing internal data forwarding or the bearer already configured on the secondary base station before handover, the destination node gNB 0 does not need to include the transport layer address and the channel identifier for data forwarding of the bearer in the HANDOVER REQUEST ACKNOWLEDGE message. The destination base station gNB 0 transmits the allocated channel information corresponding to each E-RAB to the AMF.

Step 605: the AMF sends a seventh message, which may be a forward reset response (FORWARD RELOCATION RESPONSE) message, which in this embodiment may be a FORWARD RELOCATION RESPONSE message in GTP control plane protocol signaling, to the MME.

Step 606: the MME sends an eighth message to the source node eNB 1, which may be a HANDOVER COMMAND message, which in this embodiment may be a HANDOVER COMMAND message in S1AP signaling.

The method can simplify the data forwarding process in the switching process. The above technical solution is described in the fourth embodiment in the context that the secondary base station serving the UE and the target base station are the same logical entity before handover. However, the above technical solution is not limited thereto. Besides, the above technical solution is also applicable to a scenario in which the secondary base station serving the UE and the target base station are co-located nodes (co-located nodes) before handover. Compared with other technical schemes, the technical schemes can simplify the processing procedure of the target base station by sending the UE identifier and/or the auxiliary base station identifier.

Fig. 7 is a schematic view of a fifth embodiment. The fifth embodiment describes a switching method.

In a fifth embodiment, a switching method includes the steps of:

Step 701: the first node sends a first message to a third node, wherein the first message carries UE identification information and auxiliary node identification information, and the auxiliary node identification information is identification information of a fifth node.

Step 702: and the third node sends a third message to the second node, wherein the third message carries the UE identification information and the auxiliary node identification information in the first message.

Step 703: the second node sends a fourth message to the fifth node, wherein the fourth message carries the UE identification information in the third message and the scene information indicating the current added auxiliary node.

Step 704: the fifth node sends a fifth message to the second node, and confirms that the fifth node can continue to serve as an auxiliary node after switching;

step 705: and the second node sends a sixth message to the third node, wherein the sixth message carries information indicating that the auxiliary node remains unchanged before and after switching.

Step 706: and the third node sends an eighth message to the first node, wherein the eighth message carries the information indicating that the auxiliary node remains unchanged before and after switching in the sixth message.

Fig. 8 is a schematic view of a sixth embodiment. The sixth embodiment is a specific example of applying the switching method in the fifth embodiment to an intra-system switching scenario in a 5G communication system.

In the sixth embodiment, before intra-system handover, the UE is in a dual-connection state while connected to the primary node gNB 1 and the secondary node gNB 0; after intra-system handover, the UE is still in dual-connectivity while connected to the primary node gNB2 and the secondary node gNB 0, which remains unchanged before and after the handover. It can be seen that, in the sixth embodiment, gNB 1 is the source node, gNB2 is the destination node, and the secondary nodes before and after the handover remain unchanged as gNB 0. Wherein the source node gNB 1 and the destination node gNB2 are both connected to an AMF.

The source node gNB 1 may correspond to the first node in embodiment five, the destination node gNB 2 may correspond to the second node in embodiment five, the auxiliary node gNB 0 may correspond to the fifth node in embodiment five, and the AMF may correspond to the third node in embodiment five.

In the above 5G communication system intra-system handover scenario, the handover method includes the following steps:

Step 801: the source node gNB 1 sends a first message to the AMF, where the first message may be a handover required message, and the handover required message in this embodiment may be a HANDOVER REQUIRED message in NGAP signaling, and the HANDOVER REQUIRED message carries UE identification information and auxiliary node gNB 0 identification information.

Specifically, the HANDOVER REQUIRED message may carry a Source to TARGET TRANSPARENT content field, and the Source to TARGET TRANSPARENT content field may carry a Source NG-RAN Node to Target NG-RAN Node Transparent Container field, where the Source NG-RAN Node to Target NG-RAN Node Transparent Container field carries UE identification information and secondary node gNB 0 identification information. Alternatively, the HANDOVER REQUIRED message may directly include a cell for indicating UE identification information and for indicating secondary node gNB 0 identification information, so as to directly carry the UE identification information and the secondary node gNB 0 identification information.

Specifically, the UE identification information may be a UE identification S-NG-RAN node UE XnAP ID allocated by the secondary node gNB 0 to the UE on the Xn interface. Alternatively, the UE identification information may be an identification C-RNTI allocated to the UE by the secondary node gNB 0, and when the UE identification information is the C-RNTI, the HANDOVER REQUIRED message also needs to include the secondary node identification information of the UE at PScell ID of the secondary node gNB 0 and/or gNB 0.

Step 802: the AMF sends a third message to the destination node gNB 2, where the third message may be a HANDOVER REQUEST message, where the HANDOVER REQUEST message in this embodiment may be a HANDOVER REQUEST message in NGAP signaling, where the HANDOVER REQUEST message carries the UE identification message in the HANDOVER REQUIRED message and the identification information of the auxiliary node gNB 0.

Specifically, the AMF may transparently forward the content of the Source to TARGET TRANSPARENT content received by the AMF to the destination node gNB 2. Alternatively, in step 801, if the HANDOVER REQUIRED message directly carries the UE identification information and the identification information of the secondary node gNB 0, the HANDOVER REQUEST message should also directly carry the UE identification information and the identification information of the secondary node gNB 0.

The above-described approach may be advantageous. Specifically, the destination node gNB 2 will determine, according to the received identification information of the auxiliary node gNB 0, whether the auxiliary node gNB 0 can be kept unchanged as an auxiliary node after the handover. Therefore, the auxiliary node identification information makes it possible for the auxiliary node gNB 0 before handover to be maintained after handover is completed, providing the possibility of avoiding unnecessary forwarding.

Step 803: the destination NODE gNB 2 sends a fourth message to the secondary NODE gNB 0, which may be a secondary NODE addition request message, which in this embodiment may be an S-NODE addition request (S-NODE ADDITION REQUEST) message in XnAP signaling. The S-NODE ADDITION REQUEST message includes the UE identification information, and/or an S-NODE increase trigger indication (S-NODE Addition Trigger Indication) field. The S-NODE Addition Trigger Indication field indicates that the trigger scenario of the current secondary node addition preparation process is NGRAN inter-node handover, i.e. the S-NODE Addition Trigger Indication field takes the value of inter-NGRAN HO.

In the above step, when the UE identity information is a C-RNTI, the message carrying the UE identity information further carries PScell ID of the UE at the auxiliary node gNB 0 or the auxiliary node gNB 0 identity information.

The above-described approach may be advantageous. Specifically, the inter-NGRAN-node handover is explicitly defined as a secondary-node add preparation procedure trigger scenario.

Similarly, the S-NODE Addition Trigger Indication field may also take on the value intra-NGRAN HO, such that intra-NGRAN handover may also be explicitly defined as a secondary node add preparation procedure trigger scenario.

Step 804: the secondary NODE gNB 0 sends a fifth message, which may be a secondary NODE add request acknowledgement message, which in this embodiment may be an S-NODE add request acknowledgement (S-NODE ADDITION REQUEST ACKNOWLEDGE) message in XnAP signaling, to the destination NODE gNB 2, where the S-NODE ADDITION REQUEST ACKNOWLEDGE message carries a RRC Config Indication field.

The above-described approach may be advantageous. Specifically, for the downlink data of the UE that has been transmitted to the secondary node gNB 0 before the handover is completed but has not yet been transmitted to the UE, since the secondary node gNB 0 is treated as a secondary node before the handover, the secondary node gNB 0 can find the context of the UE that has been established on the secondary node gNB 0 according to the UE identification information, and the secondary node gNB 0 does not need to forward the data before and after the handover as in the existing mechanism. When the UE identifier is C-RNTI, the auxiliary base station finds the context of the UE in gNB 0 according to PScell ID of the UE in the auxiliary node gNB 0 and/or auxiliary node identifier information of gNB 0 and the UE identifier C-RNTI.

Step 805: the destination node gNB 2 sends a sixth message to the AMF, where the sixth message may be a handover request confirm message, and the handover request confirm message may be HANDOVER REQUEST ACKNOWLEDGE messages in NGAP signaling in this embodiment. The HANDOVER REQUEST ACKNOWLEDGE message may carry a destination-to-source transparent container (Target To Source Transparent Container) field, the Target To Source Transparent Container field may carry a destination NG-RAN node-to-source NG-RAN node transparent container (Target NG-RAN Node to Source NG-RAN Node Transparent Container) field, and the Target NG-RAN Node to Source NG-RAN Node Transparent Container field may carry a UE context hold indication (UE Context Kept Indicator) field, indicating whether the UE context already on the secondary node gNB 0 will remain after the handover is completed. Alternatively, the HANDOVER REQUEST ACKNOWLEDGE message may directly contain UE Context Kept Indicator field to directly carry information about whether the UE's context already on the secondary node gNB 0 would remain after the handover is completed.

Step 806: the AMF sends an eighth message to the source node gNB 1, where the eighth message may be a HANDOVER COMMAND message, and the HANDOVER COMMAND message in this embodiment may be a HANDOVER COMMAND message in NGAP signaling, where the HANDOVER COMMAND message carries a UE Context Kept Indicator field.

Specifically, the AMF may transparently forward the content of the Target To Source Transparent Container sub-segments it receives to source node gNB 1. Alternatively, in step 805, if the HANDOVER REQUEST ACKNOWLEDGE message directly carries the UE Context Kept Indicator sub-segment, the HANDOVER COMMAND message should also directly carry the field UE Context Kept Indicator.

Step 807: the source NODE gNB 1 sends a ninth message to the secondary NODE gNB 0, which may be a secondary NODE release request message, which in this embodiment may be an S-NODE release request (S-NODE RELEASE REQUEST) message in XnAP signaling, where the S-NODE RELEASE REQUEST message includes UE Context Kept Indicator fields.

The above-described approach may be advantageous. Specifically, the secondary node gNB 0 will determine whether the context of the UE existing thereon will remain after the handover is completed according to the UE Context Kept Indicator field. Thus, it can be avoided that the data about the UE at the secondary node 0 is deleted erroneously or unnecessarily.

Step 808: the secondary NODE gNB 0 sends a tenth message, which may be a secondary NODE release request acknowledgement message, which in this embodiment may be an S-NODE release request acknowledgement (S-NODE RELEASE REQUEST ACKNOWLEDGE) message in XnAP signaling, to the source NODE gNB 1.

Fig. 9 is a schematic view of a seventh embodiment. The seventh embodiment describes a switching method.

In a seventh embodiment, a switching method includes the steps of:

Step 901: the first node sends a first message to a third node, wherein the first message carries UE identification information and auxiliary node identification information, and the auxiliary node identification information is identification information of a fifth node.

Step 902: and the third node sends a second message to the fourth node, wherein the second message carries the UE identification information and the auxiliary node identification information in the first message.

Step 903: and the fourth node sends a third message to the second node, wherein the third message carries the UE identification information and the auxiliary node identification information in the second message.

Step 904: the second node sends a fourth message to the fifth node, wherein the fourth message carries the UE identification information in the third message and the scene information indicating the current added auxiliary node.

Step 905: the fifth node sends a fifth message to the second node confirming that the fifth node can continue to act as a secondary node after the handoff.

Step 906: and the second node sends a sixth message to the fourth node, wherein the sixth message carries information indicating that the auxiliary node keeps unchanged before and after switching.

Step 907: and the fourth node sends a seventh message to the third node, wherein the seventh message carries the information indicating that the auxiliary node remains unchanged before and after switching in the sixth message.

Step 908: and the third node sends an eighth message to the first node, wherein the eighth message carries the information indicating that the auxiliary node remains unchanged before and after switching in the seventh message.

Fig. 10 is a schematic view of an eighth embodiment. The eighth embodiment is a specific example of applying the handover method in the seventh embodiment to an intra-system handover scenario in an EPS communication system.

In the eighth embodiment, before intra-system handover, the UE is in a dual-connection state while connected to the master node eNB 1 and the slave node gNB 0; after the UE performs an intra-system handover based on the S1 interface, the UE is still in a dual-connection state while being connected to the master node eNB 2 and the secondary node gNB 0 that remains unchanged before and after the handover. It can be seen that in the eighth embodiment, eNB 1 is the source node, eNB 2 is the destination node, and the secondary nodes before and after the handover remain unchanged as gNB 0. Wherein, the source node eNB 1 is connected to a source MME, and the destination node eNB 2 is connected to a destination MME.

The source node eNB 1 may correspond to the first node in embodiment seven, the destination node eNB 2 may correspond to the second node in embodiment seven, the source MME may correspond to the third node in embodiment seven, the destination MME may correspond to the fourth node in embodiment seven, and the auxiliary node gNB 0 may correspond to the fifth node in embodiment seven.

In the above-mentioned switching scenario in the EPS communication system, the switching method includes the steps of:

Step 1001: the source node eNB sends a first message to the source MME, where the first message may be a handover required message, and the handover required message may be an S1AP signaling HANDOVER REQUIRED message in this embodiment, and the HANDOVER REQUIRED message carries UE identification information and auxiliary node gNB 0 identification information.

Specifically, the HANDOVER REQUIRED message carries a field Source to TARGET TRANSPARENT Container, the Source to TARGET TRANSPARENT Container field may carry a Source eNB to destination eNB transparent Container field (Source eNB to Target eNB Transparent Container), and the Source eNB to Target eNB Transparent Container field carries UE identification information and identification information of the secondary node gNB 0. Alternatively, the HANDOVER REQUIRED message may directly include a cell for indicating UE identification information and for indicating secondary node gNB0 identification information, so as to directly carry the UE identification information and the secondary node gNB0 identification information.

Specifically, the UE identification information may be a UE identification SgNB UE X AP ID allocated by the secondary node gNB 0 to the UE on the X2 interface. Alternatively, the UE identification information may be an identification C-RNTI allocated to the UE by the secondary node gNB 0, and when the UE identification information is the C-RNTI, the HANDOVER REQUIRED message also needs to include the secondary node identification information of the UE at PScell ID of the secondary node gNB 0 and/or gNB 0.

Step 1002: the source MME sends a second message to the destination MME, where the second message may be a forwarding reset request message, where the forwarding reset request message may be a FORWARD RELOCATION REQUEST message in GTP control plane protocol signaling in this embodiment, and the FORWARD RELOCATION REQUEST message carries the UE identification message in the HANDOVER REQUIRED message and the identification information of the auxiliary node gNB 0.

Specifically, the Source MME transparently forwards the content of the Source to TARGET TRANSPARENT Container field that it receives to the destination MME. Alternatively, in step 1001, if the UE identification information and the identification information of the secondary node gNB 0 are directly carried by the HANDOVER REQUIRED message, then the FORWARD RELOCATION REQUEST message in the GTP control plane protocol signaling should also directly carry the UE identification information and the identification information of the secondary node gNB 0.

Step 1003: the destination MME sends a third message to the destination node eNB 2, where the third message may be a HANDOVER REQUEST message, and the HANDOVER REQUEST message in this embodiment may be an S1AP signaling HANDOVER REQUEST message, where the HANDOVER REQUEST message carries the UE identification message in the HANDOVER REQUIRED message and the identification information of the auxiliary node gNB 0.

Specifically, the destination MME transparently forwards the content of the Source to TARGET TRANSPARENT content field received by the destination MME to the destination node eNB 2. Alternatively, in step 1002, if the UE identification information and the identification information of the secondary node gNB 0 are directly carried by the FORWARD RELOCATION REQUEST message, the HANDOVER REQUEST message should also directly carry the UE identification information and the identification information of the secondary node gNB 0.

The above-described approach may be advantageous. Specifically, the destination node eNB 2 will determine, according to the received identification information of the auxiliary node gNB 0, whether the auxiliary node gNB 0 can be kept unchanged as an auxiliary node after the handover. Therefore, the auxiliary node identification information makes it possible for the auxiliary node gNB 0 before handover to be maintained after handover is completed, providing the possibility of avoiding unnecessary forwarding.

Step 1004: the target node eNB 2 sends a fourth message to the secondary node gNB 0, where the fourth message may be a secondary node addition request message, and the secondary node addition request message includes UE identification information and/or a secondary node addition trigger indication. The secondary node addition request message may be a SGNB addition request (SGNB ADDITION REQUEST) message in X2AP signaling in this embodiment. The SGNB ADDITION REQUEST message includes the UE identification information, and/or SGNB an increase trigger indication (SGNB Addition Trigger Indication) field. The SGNB Addition Trigger Indication field indicates that the trigger scenario for the current secondary node addition preparation procedure is an inter-eNB handover, i.e., SGNB Addition Trigger Indication field takes on the value of inter-eNB HO.

In the above step, when the UE identity information is a C-RNTI, the message carrying the UE identity information further carries PScell ID of the UE at the auxiliary node gNB 0 or the auxiliary node gNB 0 identity information.

The above-described approach may be advantageous. Specifically, inter-eNB handover is explicitly defined as a secondary node addition preparation procedure trigger scenario.

Step 1005: the secondary node gNB 0 sends a fifth message to the destination node eNB 2, where the fifth message may be a secondary node add request acknowledgement message, and the secondary node add request acknowledgement message may be a SGNB add request acknowledgement (SGNB ADDITION REQUEST ACKNOWLEDGE) message in X2AP signaling, where the SGNB ADDITION REQUEST ACKNOWLEDGE message carries a RRC Config Indication field.

The above-described approach may be advantageous. Specifically, for the downlink data of the UE that has been transmitted to the secondary node gNB 0 before the handover is completed but has not yet been transmitted to the UE, since the secondary node gNB 0 is treated as a secondary node before the handover, the secondary node gNB 0 can find the context of the UE that has been established on the secondary node gNB 0 according to the UE identification information, and the secondary node gNB 0 does not need to forward the data before and after the handover as in the existing mechanism. When the UE identifier is C-RNTI, the auxiliary base station finds the context of the UE in gNB 0 according to PScell ID of the UE in the auxiliary node gNB 0 and/or auxiliary node identifier information of gNB 0 and the UE identifier C-RNTI.

Step 1006: the destination node eNB sends a sixth message to the destination MME, where the sixth message may be a handover request acknowledgement message, and the handover request acknowledgement message may be a HANDOVER REQUEST ACKNOWLEDGE message in S1AP signaling. The HANDOVER REQUEST ACKNOWLEDGE message may carry a Target To Source Transparent Container field, the Target To Source Transparent Container field may carry a destination eNB-to-source eNB transparent container (Target eNB to Source eNB Transparent Container) field, and the Target eNB to Source eNB Transparent Container field may carry a UE Context Kept Indicator field, which indicates whether the UE context already on the secondary node gNB 0 will remain after the handover is completed. Alternatively, the HANDOVER REQUEST ACKNOWLEDGE message may directly contain UE Context Kept Indicator field to directly carry information about whether the UE's context already on the secondary node gNB 0 would remain after the handover is completed.

Step 1007: the destination MME sends a seventh message to the source MME, where the seventh message may be a forward reset response message, the forward reset response message may be a FORWARD RELOCATION RESPONSE message in a GTP control plane protocol signaling, and the FORWARD RELOCATION RESPONSE message carries the UE Context Kept Indicator in the HANDOVER REQUEST ACKNOWLEDGE message.

Specifically, the present invention relates to a method for manufacturing a semiconductor device. The destination MME may transparently forward the Target To Source Transparent Container field content it receives to the source MME. Alternatively, in step 1006, if the HANDOVER REQUEST ACKNOWLEDGE message directly carries the UE Context Kept Indicator field, then the FORWARD RELOCATION RESPONSE message in the GTP control plane protocol signaling should also directly carry the UE Context Kept Indicator field.

Step 1008: the source MME sends an eighth message to the source node eNB 1, where the eighth message may be a HANDOVER COMMAND message, and the HANDOVER COMMAND message may be a HANDOVER COMMAND message in S1AP signaling, where the HANDOVER COMMAND message carries a UE Context Kept Indicator field.

Specifically, the source MME may transparently forward the content of the Target To Source Transparent Container sub-segments it receives to the source node eNB 1. Alternatively, in step 1007, if the FORWARD RELOCATION RESPONSE message directly carries the UE Context Kept Indicator sub-segment, the HANDOVER COMMAND message should also directly carry the field UE Context Kept Indicator.

Step 1009: the source node eNB 1 sends a ninth message to the secondary node gNB 0, where the ninth message may be a secondary node release request message, and the secondary node release request message may be a SGNB release request (SGNB RELEASE REQUEST) message in X2AP signaling, and the SGNB RELEASE REQUEST message includes UE Context Kept Indicator fields.

The above-described approach may be advantageous. Specifically, the secondary node gNB 0 will determine whether the context of the UE existing thereon will remain after the handover is completed according to the UE Context Kept Indicator field. Thus, it can be avoided that the data about the UE at the secondary node 0 is deleted erroneously or unnecessarily.

Step 1010: the secondary node gNB 0 sends a tenth message to the source node eNB 1, which may be a secondary node release request acknowledgement message, which may be a SGNB release request acknowledgement (SGNB RELEASE REQUEST ACKNOWLEDGE) message in X2AP signaling.

Fig. 11 is a schematic view of a ninth embodiment. The ninth embodiment is a specific example of applying the switching method in the seventh embodiment to a scenario in which the EPS communication system switches to the 5G communication system.

In the ninth embodiment, before performing an intersystem handover, the UE is in a dual-connection state while connected to the master node eNB 1 and the auxiliary node gNB 0; after the UE performs handover from the EPS system to the 5G system, the UE is still in a dual-connection state while being connected to the primary node gNB 2 and the secondary node gNB 0 that remains unchanged before and after the handover. It can be seen that in the ninth embodiment, eNB 1 is the source node, gNB 2 is the destination node, and the secondary nodes before and after the handover remain unchanged as gNB 0. Wherein, the source node eNB 1 is connected to an MME, and the destination node gNB 2 is connected to an AMF.

The source node eNB 1 may correspond to the first node in embodiment seven, the destination node gNB 2 may correspond to the second node in embodiment seven, the MME may correspond to the third node in embodiment seven, the AMF may correspond to the fourth node in embodiment seven, and the auxiliary node gNB 0 may correspond to the fifth node in embodiment seven.

In the above scenario where the EPS communication system switches to the 5G communication system, the switching method includes the following steps:

Step 1101: the source node eNB sends a first message to the MME, where the first message may be a handover required message, the handover required message may be a HANDOVER REQUIRED message in S1AP signaling, and the HANDOVER REQUIRED message carries UE identification information and auxiliary node gNB 0 identification information.

Specifically, the HANDOVER REQUIRED message carries a field Source to TARGET TRANSPARENT Container, the Source to TARGET TRANSPARENT Container field may carry a Source NG-RAN Node to Target NG-RAN Node Transparent Container field, and the Source NG-RAN Node to Target NG-RAN Node Transparent Container field carries UE identification information and identification information of the secondary node gNB 0. Alternatively, the HANDOVER REQUIRED message may directly include a cell for indicating UE identification information and for indicating secondary node gNB0 identification information, so as to directly carry the UE identification information and the secondary node gNB0 identification information.

Specifically, the UE identification information may be a UE identification SgNB UE X AP ID allocated by the secondary node gNB 0 to the UE on the X2 interface. Alternatively, the UE identification information may be an identification C-RNTI allocated to the UE by the secondary node gNB 0, and when the UE identification information is the C-RNTI, the HANDOVER REQUIRED message also needs to include the secondary node identification information of the UE at PScell ID of the secondary node gNB 0 and/or gNB 0. Step 1102: the MME sends a second message to the AMF, where the second message may be a forwarding reset request message, the forwarding reset request message may be a FORWARD RELOCATION REQUEST message in a GTP control plane protocol signaling, and the FORWARD RELOCATION REQUEST message carries the UE identification message in the HANDOVER REQUIRED message and the identification information of the secondary node gNB 0.

Specifically, the MME transparently forwards the content of the Source to TARGET TRANSPARENT Container field received by the MME to the AMF. Alternatively, in step 1101, if the UE identification information and the identification information of the secondary node gNB 0 are directly carried by the HANDOVER REQUIRED message, then the FORWARD RELOCATION REQUEST message in the GTP control plane protocol signaling should also directly carry the UE identification information and the identification information of the secondary node gNB 0.

Step 1103: the AMF sends a third message to the destination node gNB 2, where the third message may be a HANDOVER REQUEST message, and the HANDOVER REQUEST message may be a HANDOVER REQUEST message in NGAP signaling, where the HANDOVER REQUEST message carries the UE identification message in the HANDOVER REQUIRED message and the identification information of the auxiliary node gNB 0.

Specifically, the AMF transparently forwards the received content of the Source to TARGET TRANSPARENT content field to the destination node gNB 2. Alternatively, in step 1102, if the UE identification information and the identification information of the secondary node gNB 0 are directly carried by the FORWARD RELOCATION REQUEST message, then the HANDOVER REQUEST message in the NGAP signaling should also directly carry the UE identification information and the identification information of the secondary node gNB 0.

The above-described approach may be advantageous. Specifically, the destination node gNB 2 will determine, according to the received identification information of the auxiliary node gNB 0, whether the auxiliary node gNB 0 can be kept unchanged as an auxiliary node after the handover. Therefore, the auxiliary node identification information makes it possible for the auxiliary node gNB 0 before handover to be maintained after handover is completed, providing the possibility of avoiding unnecessary forwarding.

Step 1104: the destination node gNB 2 sends a fourth message to the auxiliary node gNB 0, where the fourth message may be an auxiliary node addition request message, and the auxiliary node addition request message includes UE identification information and/or an auxiliary node addition trigger indication. The secondary node addition request message may be an S-NODE ADDITION REQUEST message in XnAP signaling. The S-NODE ADDITION REQUEST message includes the UE identification information and/or an S-NODE Addition Trigger Indication field. The S-NODE Addition Trigger Indication field indicates that the trigger scenario of the current auxiliary node adding preparation process is an eNB-NGRAN inter-node handover, i.e. the S-NODE Addition Trigger Indication field takes on the value of eNB-NGRAN HO.

In the above step, when the UE identity information is a C-RNTI, the message carrying the UE identity information further carries PScell ID of the UE at the auxiliary node gNB 0 or the auxiliary node gNB 0 identity information.

The above-described approach may be advantageous. Specifically, the inter-eNB-NGRAN node handover is explicitly defined as a secondary node adding preparation procedure triggering scenario.

Step 1105: the secondary node gNB 0 sends a fifth message to the destination node gNB 2, where the fifth message may be a secondary node add request acknowledgement message, and the secondary node add request acknowledgement message may be an S-NODE ADDITION REQUEST ACKNOWLEDGE message in XnAP signaling, where the S-NODE ADDITION REQUEST ACKNOWLEDGE message carries a RRC Config Indication field.

The above-described approach may be advantageous. Specifically, for the downlink data of the UE that has been transmitted to the secondary node gNB 0 before the handover is completed but has not yet been transmitted to the UE, since the secondary node gNB 0 is treated as a secondary node before the handover, the secondary node gNB 0 can find the context of the UE that has been established on the secondary node gNB 0 according to the UE identification information, and the secondary node gNB 0 does not need to forward the data before and after the handover as in the existing mechanism. When the UE identifier is C-RNTI, the auxiliary base station finds the context of the UE in gNB 0 according to PScell ID of the UE in the auxiliary node gNB 0 and/or auxiliary node identifier information of gNB 0 and the UE identifier C-RNTI.

Step 1106: the destination node gNB 2 sends a sixth message to the AMF, where the sixth message may be a handover request confirm message, and the handover request confirm message may be a HANDOVER REQUEST ACKNOWLEDGE message in NGAP signaling. The HANDOVER REQUEST ACKNOWLEDGE message may carry a Target To Source Transparent Container field, the Target To Source Transparent Container field may carry a Target NG-RAN Node to Source NG-RAN Node Transparent Container field, and the Target NG-RAN Node to Source NG-RAN Node Transparent Container field may carry a UE Context Kept Indicator field, which indicates whether the context of the UE existing on the secondary node gNB 0 will be preserved after the handover is completed. Alternatively, the HANDOVER REQUEST ACKNOWLEDGE message may directly contain UE Context Kept Indicator field to directly carry information about whether the UE's context already on the secondary node gNB 0 would remain after the handover is completed.

Step 1107: the AMF sends a seventh message to the MME, the seventh message may be a forward reset response message, the forward reset response message may be a FORWARD RELOCATION RESPONSE message in GTP control plane protocol signaling, and the FORWARD RELOCATION RESPONSE message carries the UE Context Kept Indicator in the HANDOVER REQUEST ACKNOWLEDGE message.

Specifically, the present invention relates to a method for manufacturing a semiconductor device. The AMF transparently forwards the contents of the Target To Source Transparent Container field it receives to the MME. Alternatively, in step 1106, if the HANDOVER REQUEST ACKNOWLEDGE message directly carries the UE Context Kept Indicator field, then the FORWARD RELOCATION RESPONSE message in the GTP control plane protocol signaling should also directly carry the UE Context Kept Indicator field.

Step 1108: the MME sends an eighth message to the source node eNB 1, where the eighth message may be a HANDOVER COMMAND message, and the HANDOVER COMMAND message may be a HANDOVER COMMAND message in S1AP signaling, where the HANDOVER COMMAND message carries a UE Context Kept Indicator field.

Specifically, the MME may transparently forward the content of the Target To Source Transparent Container sub-segments it receives to source node eNB 1. Alternatively, in step 1107, if the FORWARD RELOCATION RESPONSE message directly carries the UE Context Kept Indicator sub-segment, the HANDOVER COMMAND message should also directly carry the field UE Context Kept Indicator.

Step 1109: the source node eNB 1 sends a ninth message to the secondary node gNB 0, where the ninth message may be a secondary node release request message, and the secondary node release request message may be a SGNB RELEASE REQUEST message in X2AP signaling, and the SGNB RELEASE REQUEST message includes a UE Context Kept Indicator field.

The above-described approach may be advantageous. Specifically, the secondary node gNB 0 will determine whether the context of the UE existing thereon will remain after the handover is completed according to the UE Context Kept Indicator field. Thus, it can be avoided that the data about the UE at the secondary node 0 is deleted erroneously or unnecessarily.

Step 1110: the secondary node gNB 0 sends a tenth message to the source node eNB 1, where the tenth message may be a secondary node release request acknowledgement message, and the secondary node release request acknowledgement message may be a SGNB RELEASE REQUEST ACKNOWLEDGE message in X2AP signaling.

Fig. 12 is a schematic view of a tenth embodiment. The tenth embodiment is a specific example of a scenario in which the switching method in the seventh embodiment is applied to switching of the EPS communication system of the 5G communication system.

In the tenth embodiment, before performing an intersystem handover, the UE is in a dual-connection state while being connected to the primary node gNB 1 and the secondary node gNB 0; after the UE performs handover from the 5G system to the EPS system, the UE is still in the dual-connection state while being connected to the master node eNB 2 and the secondary node gNB 0 that remains unchanged before and after the handover. It can be seen that, in the tenth embodiment, gNB 1 is the source node, eNB 2 is the destination node, and the secondary nodes before and after the handover remain unchanged as gNB 0. Wherein, the source node gNB 1 is connected to the AMF, and the destination node gNB 2 is connected to the MME.

The source node gNB 1 may correspond to the first node in embodiment seven, the destination node eNB 2 may correspond to the second node in embodiment seven, the AMF may correspond to the third node in embodiment seven, the MME may correspond to the fourth node in embodiment seven, and the auxiliary node gNB 0 may correspond to the fifth node in embodiment seven.

In the scenario of switching the 5G communication system to the EPS communication system, the switching method includes the following steps:

Step 1201: the source node gNB 1 sends a first message to the AMF, where the first message may be a handover required message, the handover required message may be a HANDOVER REQUIRED message in NGAP signaling, and the HANDOVER REQUIRED message carries UE identification information and auxiliary node gNB 0 identification information.

Specifically, the HANDOVER REQUIRED message carries a field Source to TARGET TRANSPARENT Container, the Source to TARGET TRANSPARENT Container field may carry a Source eNB to Target eNB Transparent Container field, and the Source eNB to Target eNB Transparent Container field carries UE identification information and identification information of the secondary node gNB 0. Alternatively, the HANDOVER REQUIRED message may directly include a cell for indicating UE identification information and for indicating secondary node gNB 0 identification information, so as to directly carry the UE identification information and the secondary node gNB 0 identification information.

Specifically, the UE identification information may be a UE identification S-NG-RAN node UE XnAP ID allocated by the secondary node gNB 0 to the UE on the Xn interface. Alternatively, the UE identification information may be an identification C-RNTI allocated to the UE by the secondary node gNB 0, and when the UE identification information is the C-RNTI, the HANDOVER REQUIRED message also needs to include the secondary node identification information of the UE at PScell ID of the secondary node gNB 0 and/or gNB 0. Step 1202: the AMF sends a second message to the MME, where the second message may be a forwarding reset request message, and the forwarding reset request message may be a FORWARD RELOCATION REQUEST message in a GTP control plane protocol signaling, and the FORWARD RELOCATION REQUEST message carries the UE identification message in the HANDOVER REQUIRED message and the identification information of the auxiliary node gNB 0.

Specifically, the AMF transparently forwards the content of the Source to TARGET TRANSPARENT Container field received by the AMF to the MME. Alternatively, in step 1201, if the UE identification information and the identification information of the secondary node gNB 0 are directly carried by the HANDOVER REQUIRED message, then the FORWARD RELOCATION REQUEST message in the GTP control plane protocol signaling should also directly carry the UE identification information and the identification information of the secondary node gNB 0.

Step 1203: the MME sends a third message to the destination node eNB 2, where the third message may be a HANDOVER REQUEST message, and the HANDOVER REQUEST message may be a HANDOVER REQUEST message in S1AP signaling, where the HANDOVER REQUEST message carries the UE identification message in the HANDOVER REQUIRED message and the identification information of the auxiliary node gNB 0.

Specifically, the MME transparently forwards the content of the Source to TARGET TRANSPARENT Container field received by the MME to the destination node eNB 2. Alternatively, in step 1202, if the UE identification information and the identification information of the secondary node gNB 0 are directly carried by the FORWARD RELOCATION REQUEST message, the HANDOVER REQUEST message in the S1AP signaling should also directly carry the UE identification information and the identification information of the secondary node gNB 0.

The above-described approach may be advantageous. Specifically, the destination node eNB 2 will determine, according to the received identification information of the auxiliary node gNB 0, whether the auxiliary node gNB 0 can be kept unchanged as an auxiliary node after the handover. Therefore, the auxiliary node identification information makes it possible for the auxiliary node gNB 0 before handover to be maintained after handover is completed, providing the possibility of avoiding unnecessary forwarding.

Step 1204: the target node eNB 2 sends a fourth message to the secondary node gNB 0, where the fourth message may be a secondary node addition request message, and the secondary node addition request message includes UE identification information and/or a secondary node addition trigger indication. The secondary node addition request message may be SGNB ADDITION REQUEST messages in X2AP signaling. The SGNB ADDITION REQUEST message includes the UE identification information, and/or SGNB Addition Trigger Indication field. The SGNB Addition Trigger Indication field indicates that the trigger scenario for the current secondary node addition preparation procedure is NGRAN-inter-eNB handover, i.e., SGNB Addition Trigger Indication field takes on the value NGRAN-eNB HO.

In the above step, when the UE identity information is a C-RNTI, the message carrying the UE identity information further carries PScell ID of the UE at the auxiliary node gNB 0 or the auxiliary node gNB 0 identity information.

The above-described approach may be advantageous. Specifically, NGRAN-inter-eNB handover is explicitly defined as a secondary node add preparation procedure trigger scenario.

Step 1205: the secondary node gNB 0 sends a fifth message to the destination node eNB 2, where the fifth message may be a secondary node addition request acknowledgement message, and the secondary node addition request acknowledgement message may be a SGNB ADDITION REQUEST ACKNOWLEDGE message in X2AP signaling, where the SGNB ADDITION REQUEST ACKNOWLEDGE message carries a RRC Config Indication field.

The above-described approach may be advantageous. Specifically, for the downlink data of the UE that has been transmitted to the secondary node gNB 0 before the handover is completed but has not yet been transmitted to the UE, since the secondary node gNB 0 is treated as a secondary node before the handover, the secondary node gNB 0 can find the context of the UE that has been established on the secondary node gNB 0 according to the UE identification information, and the secondary node gNB 0 does not need to forward the data before and after the handover as in the existing mechanism. When the UE identifier is C-RNTI, the auxiliary base station finds the context of the UE in gNB 0 according to PScell ID of the UE in the auxiliary node gNB 0 and/or auxiliary node identifier information of gNB 0 and the UE identifier C-RNTI.

Step 1206: the destination node eNB 2 sends a sixth message to the MME, where the sixth message may be a handover request confirm message, and the handover request confirm message may be a HANDOVER REQUEST ACKNOWLEDGE message in S1AP signaling. The HANDOVER REQUEST ACKNOWLEDGE message may carry Target To Source Transparent Container field, the Target To Source Transparent Container field may carry Target eNB to Source eNB Transparent Container field, and the Target eNB to Source eNB Transparent Container field may carry UE Context Kept Indicator field, which indicates whether the UE context existing on the secondary node gNB 0 will remain after the handover is completed. Alternatively, the HANDOVER REQUEST ACKNOWLEDGE message may directly contain UE Context Kept Indicator field to directly carry information about whether the UE's context already on the secondary node gNB 0 would remain after the handover is completed.

Step 1207: the MME sends a seventh message to the AMF, where the seventh message may be a forward reset response message, the forward reset response message may be a FORWARD RELOCATION RESPONSE message in GTP control plane protocol signaling, and the FORWARD RELOCATION RESPONSE message carries the UE Context Kept Indicator in the HANDOVER REQUEST ACKNOWLEDGE message.

Specifically, the present invention relates to a method for manufacturing a semiconductor device. The MME transparently forwards the contents of the Target To Source Transparent Container fields it receives to the AMF. Alternatively, in step 1206, if the HANDOVER REQUEST ACKNOWLEDGE message directly carries the UE Context Kept Indicator field, then the FORWARD RELOCATION RESPONSE message in the GTP control plane protocol signaling should also directly carry the UE Context Kept Indicator field.

Step 1208: the AMF sends an eighth message to the source node gNB 1, where the eighth message may be a HANDOVER COMMAND message, and the HANDOVER COMMAND message may be a HANDOVER COMMAND message in NGAP signaling, where the HANDOVER COMMAND message carries a UE Context Kept Indicator field.

Specifically, the AMF may transparently forward the content of the Target To Source Transparent Container sub-segments it receives to source node gNB 1. Alternatively, in step 1207, if the FORWARD RELOCATION RESPONSE message directly carries the UE Context Kept Indicator sub-segment, the HANDOVER COMMAND message should also directly carry the field UE Context Kept Indicator.

Step 1209: the source NODE gNB 1 sends a ninth message to the secondary NODE gNB 0, which may be a secondary NODE release request message, which may be an S-NODE release request (S-NODE RELEASE REQUEST) message in XnAP signaling, the S-NODE RELEASE REQUEST message including UE Context Kept Indicator fields.

The above-described approach may be advantageous. Specifically, the secondary node gNB 0 will determine whether the context of the UE existing thereon will remain after the handover is completed according to the UE Context Kept Indicator field. Thus, it can be avoided that the data about the UE at the secondary node 0 is deleted erroneously or unnecessarily.

Step 1210: the secondary NODE gNB 0 sends a tenth message, which may be a secondary NODE release request acknowledgement message, which may be an S-NODE release request acknowledgement (S-NODE RELEASE REQUEST ACKNOWLEDGE) message in XnAP signaling, to the source NODE gNB 1.

Fig. 13 is a schematic view of an eleventh embodiment. The eleventh embodiment is a specific example of applying the switching method in the seventh embodiment to a switching scenario within a 5G communication system.

In the eleventh embodiment, before performing an intersystem handover, the UE is in a dual-connection state while connected to the primary node gNB 1 and the secondary node gNB 0; after the UE performs intra-5G system handover, the UE is still in a dual-connection state while connected to the primary node gNB 2 and the secondary node gNB 0 that remains unchanged before and after the handover. It can be seen that, in the eleventh embodiment, gNB 1 is the source node, gNB 2 is the destination node, and the secondary nodes before and after the handover remain unchanged as gNB 0. Wherein, the source node gNB 1 is connected to the source AMF, and the destination node gNB 2 is connected to the destination AMF.

The source node gNB 1 may correspond to the first node in embodiment seven, the destination node gNB 2 may correspond to the second node in embodiment seven, the source AMF may correspond to the third node in embodiment seven, the destination AMF may correspond to the fourth node in embodiment seven, and the auxiliary node gNB 0 may correspond to the fifth node in embodiment seven.

In the above-mentioned scenario of handover in a 5G communication system, the handover method includes the steps of:

Step 1301: the source node gNB 1 sends a first message to the source AMF, where the first message may be a handover required message, the handover required message may be a HANDOVER REQUIRED message in NGAP signaling, and the HANDOVER REQUIRED message carries UE identification information and secondary node gNB 0 identification information.

Specifically, the HANDOVER REQUIRED message carries a field Source to TARGET TRANSPARENT Container, the Source to TARGET TRANSPARENT Container field may carry a Source NG-RAN Node to Target NG-RAN Node Transparent Container field, and the Source NG-RAN Node to Target NG-RAN Node Transparent Container field carries UE identification information and identification information of the secondary node gNB 0. Alternatively, the HANDOVER REQUIRED message may directly include a cell for indicating UE identification information and for indicating secondary node gNB0 identification information, so as to directly carry the UE identification information and the secondary node gNB0 identification information.

Specifically, the UE identification information may be a UE identification S-NG-RAN node UE XnAP ID allocated by the secondary node gNB 0 to the UE on the Xn interface. Alternatively, the UE identification information may be an identification C-RNTI allocated to the UE by the secondary node gNB 0, and when the UE identification information is the C-RNTI, the HANDOVER REQUIRED message also needs to include the secondary node identification information of the UE at PScell ID of the secondary node gNB 0 and/or gNB 0.

Step 1302: the source AMF sends a second message to the destination AMF, where the second message may be a Namf _communication_ CreateUEContext request (Namf _communication_ CreateUEContext Request) message in an AMF interface signaling, and the Namf _communication_ CreateUEContext Request message carries the UE identification message in the HANDOVER REQUIRED message and the identification information of the auxiliary node gNB 0.

Specifically, the Source AMF transparently forwards the content of the Source to TARGET TRANSPARENT Container field received by the Source AMF to the destination AMF. Alternatively, in step 1301, if the UE identification information and the identification information of the secondary node gNB 0 are directly carried by the HANDOVER REQUIRED message, then the Namf _communication_ CreateUEContext Request message in the AMF interface signaling should also directly carry the UE identification information and the identification information of the secondary node gNB 0.

Step 1303: the source AMF sends a third message to the destination node gNB 2, where the third message may be a HANDOVER REQUEST message, and the HANDOVER REQUEST message may be a HANDOVER REQUEST message in NGAP signaling, where the HANDOVER REQUEST message carries the UE identification message in HANDOVER REQUIRED messages and the identification information of the auxiliary node gNB 0.

Specifically, the AMF transparently forwards the received content of the Source to TARGET TRANSPARENT content field to the destination node gNB 2. Alternatively, in step 1302, if the UE identification information and the identification information of the secondary node gNB 0 are directly carried by the Namf _communication_ CreateUEContext Request message in the AMF interface signaling, the HANDOVER REQUEST message in the NGAP signaling should also directly carry the UE identification information and the identification information of the secondary node gNB 0.

The above-described approach may be advantageous. Specifically, the destination node gNB 2 will determine, according to the received identification information of the auxiliary node gNB 0, whether the auxiliary node gNB 0 can be kept unchanged as an auxiliary node after the handover. Therefore, the auxiliary node identification information makes it possible for the auxiliary node gNB 0 before handover to be maintained after handover is completed, providing the possibility of avoiding unnecessary forwarding.

Step 1304: the destination node gNB 2 sends a fourth message to the auxiliary node gNB 0, where the fourth message may be an auxiliary node addition request message, and the auxiliary node addition request message includes UE identification information and/or an auxiliary node addition trigger indication. The secondary node addition request message may be an S-NODE ADDITION REQUEST message in XnAP signaling. The S-NODE ADDITION REQUEST message includes the UE identification information and/or an S-NODE Addition Trigger Indication field. The S-NODE Addition Trigger Indication field indicates that the trigger scenario of the current secondary node addition preparation process is NGRAN inter-node handover, i.e. the S-NODE Addition Trigger Indication field takes the value of inter-NGRAN HO.

In the above step, when the UE identity information is a C-RNTI, the message carrying the UE identity information further carries PScell ID of the UE at the auxiliary node gNB 0 or the auxiliary node gNB 0 identity information.

The above-described approach may be advantageous. Specifically, the inter-NGRAN-node handover is explicitly defined as a secondary-node add preparation procedure trigger scenario.

Step 1305: the secondary node gNB 0 sends a fifth message to the destination node gNB 2, where the fifth message may be a secondary node add request acknowledgement message, and the secondary node add request acknowledgement message may be an S-NODE ADDITION REQUEST ACKNOWLEDGE message in XnAP signaling, where the S-NODE ADDITION REQUEST ACKNOWLEDGE message carries a RRC Config Indication field.

The above-described approach may be advantageous. Specifically, for the downlink data of the UE that has been transmitted to the secondary node gNB 0 before the handover is completed but has not yet been transmitted to the UE, since the secondary node gNB 0 is treated as a secondary node before the handover, the secondary node gNB 0 can find the context of the UE that has been established on the secondary node gNB 0 according to the UE identification information, and the secondary node gNB 0 does not need to forward the data before and after the handover as in the existing mechanism. When the UE identifier is C-RNTI, the auxiliary base station finds the context of the UE in gNB 0 according to PScell ID of the UE in the auxiliary node gNB 0 and/or auxiliary node identifier information of gNB 0 and the UE identifier C-RNTI.

Step 1306: the destination node gNB 2 sends a sixth message to the destination AMF, where the sixth message may be a handover request confirm message, and the handover request confirm message may be a HANDOVER REQUEST ACKNOWLEDGE message in NGAP signaling. The HANDOVER REQUEST ACKNOWLEDGE message may carry a Target To Source Transparent Container field, the Target To Source Transparent Container field may carry a Target NG-RAN Node to Source NG-RAN Node Transparent Container field, and the Target NG-RAN Node to Source NG-RAN Node Transparent Container field may carry a UE Context Kept Indicator field, which indicates whether the context of the UE existing on the secondary node gNB 0 will be preserved after the handover is completed. Alternatively, the HANDOVER REQUEST ACKNOWLEDGE message may directly contain UE Context Kept Indicator field to directly carry information about whether the UE's context already on the secondary node gNB 0 would remain after the handover is completed.

Step 1307: the destination AMF sends a seventh message to the source AMF, where the seventh message may be a Namf _communication_ CreateUEContext response (Namf _communication_ CreateUEContext Response) message in AMF interface signaling, and the Namf _communication_ CreateUEContext Response message in AMF interface signaling carries the UE Context Kept Indicator in the HANDOVER REQUEST ACKNOWLEDGE message.

Specifically, the present invention relates to a method for manufacturing a semiconductor device. The destination AMF transparently forwards the contents of the Target To Source Transparent Container fields it receives to the source AMF. Alternatively, in step 1306, if the HANDOVER REQUEST ACKNOWLEDGE message directly carries the UE Context Kept Indicator field, then the Namf _communication_ CreateUEContext Response message in the AMF interface signaling should also directly carry the UE Context Kept Indicator field.

Step 1308: the source AMF sends an eighth message to the source node gNB 1, where the eighth message may be a HANDOVER COMMAND message, and the HANDOVER COMMAND message may be a HANDOVER COMMAND message in NGAP signaling, where the HANDOVER COMMAND message carries a UE Context Kept Indicator field.

Specifically, the source AMF may transparently forward the content of the Target To Source Transparent Container sub-segments it receives to source node gNB 1. Alternatively, in step 1307, if the AMF interface signaling Namf _communication_ CreateUEContext Response directly carries the UE Context Kept Indicator sub-segment, the HANDOVER COMMAND signaling should also directly carry the field UE Context Kept Indicator.

Step 1309: the source node gNB 1 sends a ninth message to the secondary node gNB 0, where the ninth message may be a secondary node release request message, the secondary node release request message may be an S-NODE RELEASE REQUEST message in XnAP signaling, and the S-NODE RELEASE REQUEST message includes a UE Context Kept Indicator field.

The above-described approach may be advantageous. Specifically, the secondary node gNB 0 will determine whether the context of the UE existing thereon will remain after the handover is completed according to the UE Context Kept Indicator field. Thus, it is possible to avoid that data about the UE at the secondary node 0 is deleted erroneously or unnecessarily.

Step 1310: the secondary node gNB 0 sends a tenth message to the source node gNB 1, where the tenth message may be a secondary node release request acknowledgement message, and the secondary node release request acknowledgement message may be an S-NODE RELEASE REQUEST ACKNOWLEDGE message in XnAP signaling.

Fig. 14 is a schematic view of a twelfth embodiment. The twelfth embodiment is a specific example of applying the handover method in the third embodiment to a handover scenario from a 5G communication system to EPS.

In a twelfth embodiment, the UE is connected only to gNB 0 prior to an intersystem handover; after the intersystem handover, the UE is in a dual-connection state while being connected to the master node eNB1 and the secondary node gNB 0. It can be seen that in the twelfth embodiment, the gNB 0 is a source node, the eNB1 is a destination node, and the source node is a secondary node after handover. Wherein, the source base station gNB 0 is connected to an AMF, and the target base station eNB1 is connected to an MME.

The source node gNB 0 may correspond to the first node in embodiment three, the destination node eNB 1 may correspond to the second node in embodiment three, the AMF may correspond to the third node in embodiment three, and the MME may correspond to the fourth node in embodiment three.

In the above handover scenario from the 5G communication system to the EPS system, the handover method includes the following steps:

Step 1401: the source node gNB 0 sends a first message to the AMF, where the first message may be a handover required message, which in this implementation may be a HANDOVER REQUIRED message in NGAP signaling. The HANDOVER REQUIRED message carries a source base station identifier, and/or a source cell identifier, and/or UE identifier information, and/or a measurement result of the UE.

Specifically, the HANDOVER REQUIRED message carries a Source to TARGET TRANSPARENT content field, and when the destination node is an E-UTRAN base station, the Source to TARGET TRANSPARENT content field may carry a Source eNB to Target eNB Transparent Container field, and the Source eNB to Target eNB Transparent Container field carries a Source base station identifier and/or a Source cell identifier and/or UE identification information and/or a measurement result of the UE. Alternatively, the HANDOVER REQUIRED message may directly contain the source base station identity, and/or source cell identity, and/or UE identity information, and/or measurement results of the UE. Specifically, the UE identification information may be a C-RNTI allocated to the UE by the source node gNB 0. In case the UE identity is a C-RNTI, the identity of the source cell also needs to be carried directly by the HANDOVER REQUIRED message or in the Source eNB to Target eNB Transparent Container field.

Step 1402: the AMF sends a second message to the MME, where the second message may be a forwarding reset request message, where the forwarding reset request message may be FORWARD RELOCATION REQUEST messages in GTP control plane protocol signaling in this embodiment, and the FORWARD RELOCATION REQUEST message carries the source base station identifier and/or source cell identifier and/or UE identifier and/or measurement result of the UE in HANDOVER REQUIRED message.

Specifically, the AMF transparently forwards the content of the Source to TARGET TRANSPARENT Container field received by the AMF to the MME. Alternatively, in step 1401, if the source base station identity, and/or source cell identity, and/or UE measurement result is directly carried by the HANDOVER REQUIRED message, then the GTP control plane protocol signaling should also directly carry the source base station identity, and/or source cell identity, and/or UE measurement result.

Step 1403: the MME sends a third message to the target base station eNB 1, where the third message may be a HANDOVER REQUEST message, and the HANDOVER REQUEST message may be an S1AP signaling HANDOVER REQUEST message in this embodiment, where the HANDOVER REQUEST message carries the source base station identifier and/or source cell identifier and/or UE identifier and/or measurement result of the UE in the HANDOVER REQUIRED message.

Specifically, the MME transparently forwards the content of the Source to TARGET TRANSPARENT content field received by the MME to the target base station eNB1. Alternatively, in step 1402, if the GTP control plane protocol signaling directly carries the source base station identity, and/or source cell identity, and/or UE measurement result, the HANDOVER REQUEST message should also directly carry the source base station identity, and/or source cell identity, and/or UE measurement result.

In step 1404, the target eNB 1 decides to initiate a secondary node addition procedure to the source gNB 0. The target eNB 1 decides to initiate an SN addition procedure to the source gNB 0 according to the received UE measurement report, and/or the source base station identity, and/or the source cell identity.

The target eNB 1 sends an SN addition request message to the gNB 0. The auxiliary node addition request message comprises a UE identifier distributed to the UE by the source base station and/or a source cell identifier. The UE identity is a UE identity received from the source base station gNB0 through a handover request message. The message contains bearer information to be configured onto gNB 0.

The gNB 0 receives the secondary node addition request message. The gNB 0 can find the UE context according to the UE identity and/or the source cell identity received in the message. For bearers configured onto the gNB 0 (e.g., bearers terminating at the secondary node or SCG bearers), the gNB 0 need not allocate a transport layer address and a channel identification for data forwarding. And gNB 0 performs internal data forwarding.

If gNB0 supports a control plane and user plane separated architecture, gNB0 includes a gNB centralized unit control plane unit (gNB-CU-CP) and a gNB centralized unit user plane unit (gNB-CU-UP). gNB0-CU-CP requests gNB0-CU-UP to allocate channel information corresponding to each evolved radio access bearer E-RAB for the bearer terminated at gNB 0-CU-UP. The channel information includes a transport layer address and a channel identification. The gNB0-CU-UP allocates channel information for data forwarding for each E-RAB requested and sends the channel information to the gNB0-CU-CP. And the gNB0-CU-CP does not need to request gNB0-CU-UP to allocate channel information for the E-RAB corresponding to the bearer terminated at the target end at the eNB 1. The gNB0-CU-CP can find the UE context according to the received UE identification and/or the source cell identification. The gNB0-CU-CP knows the bearer terminated at the gNB0-CU-UP at the destination end based on the UE context. The identity of gNB0-CU-CP is the same as the secondary base station identity of gNB 0.

GNB 0 sends an SN increase request acknowledgement message to eNB 1.gNB 0 need not include a transport layer address and channel identification for data forwarding into the message. The secondary node addition request acknowledgement message contains the UE identity of the interface between the gNB 0 and eNB 1 allocated by the gNB 0. The UE identity may be SgNB UE X AP ID or S-NG-RAN node UE XnAP ID.

Step 1405: the target eNB1 sends a sixth message to the MME, where the sixth message may be a handover request confirm message, and the handover request confirm message may be HANDOVER REQUEST ACKNOWLEDGE messages in S1AP signaling in this embodiment. For the bearer for performing internal data forwarding or the bearer to be configured on the source base station after handover, the destination node eNB1 does not need to include the transport layer address and the channel identifier for data forwarding of the bearer in the HANDOVER REQUEST ACKNOWLEDGE message. The HANDOVER REQUEST ACKNOWLEDGE message directly carries or Target to Source Transparent Container in the HANDOVER REQUEST ACKNOWLEDGE message carries a UE identifier of an interface between the gNB0 and the eNB1 allocated by the gNB0, and/or a secondary base station identifier of the gNB0, and/or a destination base station identifier of the eNB 1.

Step 1406: the MME sends a seventh message to the AMF, which may be a forwarded reset response message, which in this embodiment may be a FORWARD RELOCATION RESPONSE message in GTP control plane protocol signaling. The FORWARD RELOCATION RESPONSE message carries the UE identifier of the interface between the gNB 0 and the eNB1 allocated by the gNB 0, and/or the auxiliary base station identifier of the gNB 0, and/or the destination base station identifier of the eNB 1.

Step 1407: the AMF sends an eighth message to the source base station gNB 0, where the eighth message may be a HANDOVER COMMAND message, and the HANDOVER COMMAND message may be a HANDOVER COMMAND message in NGAP signaling in this embodiment. The HANDOVER COMMAND message carries the UE identifier of the interface between the gNB 0 and the eNB 1 allocated by the gNB 0, and/or the secondary base station identifier of the gNB 0, and/or the destination base station identifier of the eNB 1.

GNB 0 finds the UE context according to the received UE identifier of the interface between gNB 0 and eNB allocated by gNB 0, and/or the auxiliary base station identifier of gNB 0, and/or the destination base station identifier of eNB 1. For a bearer (e.g., a bearer terminated in a secondary node or SCG bearer) configured onto the gNB 0 at the target base station eNB 1, the gNB 0 performs internal data forwarding.

If gNB0 supports a control plane and user plane separated architecture, gNB0-CU-CP receives channel information for each corresponding E-RAB for data forwarding. The channel information includes a transport layer address and a channel identification. The gNB0-CU-CP sends channel information corresponding to each E-RAB to the gNB0-CU-UP. And the gNB0-CU-CP does not need to send the channel information of the E-RAB to the gNB0-CU-UP corresponding to the bearer which is terminated at the destination end at the gNB0-CU-UP. For the bearer terminated at the destination end at the destination node eNB1, the gNB0-CU-CP sends the channel information of the E-RAB to the gNB0-CU-UP. And the gNB0-CU-CP finds the UE context according to the received UE identifier of the interface between gNB0 and eNB allocated by the gNB0-CU-CP, and/or the auxiliary base station identifier of gNB0, and/or the destination base station identifier of eNB1. The gNB0-CU-CP knows the bearer terminated at the gNB0-CU-UP at the destination end based on the UE context. The identity of gNB0-CU-CP is the same as the secondary base station identity of gNB 0. And for the bearer ending in the gNB0-CU-UP at the destination end, carrying out internal data forwarding on the gNB0-CU-UP. For bearers terminated at the destination end at eNB1, the gNB0-CU-UP forwards data to eNB1. For direct data forwarding, gNB0-CU-UP sends data to the channel corresponding to each E-RAB. The data sent by the gNB0-CU-UP to each E-RAB channel has no quality of service assurance (QFI) information for the Qos flow. And the gNB0-CU-UP sends the data of each Qos flow to a corresponding E-RAB channel according to the corresponding relation between the Qos flow and the E-RAB.

Step 1408, a subsequent handover procedure is performed.

The method can simplify the data forwarding process in the switching process. The above technical solution is described in the fourteenth embodiment in the scenario that the source base station and the secondary base station serving the UE after the handover are the same logical entity. However, the above technical solution is not limited thereto. In addition, the technical scheme is suitable for the scenario that the auxiliary base station serving the UE and the source base station are co-located nodes after switching. In one aspect, the source base station sends the source base station identifier, and/or the source cell identifier, and/or the UE identifier, and/or the measurement result of the UE to the destination base station, and the destination base station sends the measurement result to the source base station serving as the secondary base station, so that the source base station performs internal data forwarding for a bearer configured on the source base station (for example, a bearer terminated at the secondary node or an SCG bearer). On the other hand, the destination base station may also send, to the source base station gNB 0, the UE identifier of the interface between the gNB 0 and the eNB and/or the auxiliary node identifier of the gNB 0 allocated by the gNB 0 and/or the destination node identifier of the eNB 1, where the gNB 0 finds the UE context according to the received UE identifier and/or the auxiliary node identifier of the gNB 0 and/or the destination node identifier of the eNB 1, and for a bearer configured on the gNB 0 by the destination base station eNB 1 (for example, a bearer terminated at the auxiliary node or an SCG bearer), the gNB 0 performs internal data forwarding. The technical scheme comprises that the two aspects are implemented in a combined or independent mode. Compared with other technical schemes, the technical scheme does not need to forward the data from the source base station to the destination base station and from the destination main base station to the destination auxiliary base station as in the existing switching mechanism.

In summary, according to the present invention, the auxiliary node identification information makes it possible for the connection with the auxiliary node before the handover to be maintained after the handover is completed, providing the possibility of avoiding unnecessary forwarding; further, the secondary node may determine whether the context of the UE existing thereon is preserved after the handover is completed according to the related information, so as to avoid that data about the UE is deleted erroneously or unnecessarily; further, for the downlink data of the UE which is transmitted to the auxiliary node before the switching is finished but is not transmitted to the UE, when the auxiliary node is used as the auxiliary node before the switching, the auxiliary node can find the context of the UE which is built on the auxiliary node according to the UE identification information, the auxiliary node does not need to forward the data before and after the switching as in the prior mechanism, the resource waste is avoided, and the time delay of the downlink data is reduced; still further, a secondary node addition preparation process trigger scenario is defined that is not explicitly defined in existing mechanisms.

The embodiments of the present invention have been described above, and it should be understood that these descriptions are illustrative only and not limiting. In addition, the definition of "base station" and "node" in the above is equally applicable and understandable.

Those skilled in the art will appreciate that the present application includes apparatuses related to performing one or more of the operations described herein. These devices may be specially designed and constructed for the required purposes, or may comprise known devices in general purpose computers. These devices have computer programs stored therein that are selectively activated or reconfigured. Such a computer program may be stored in a device (e.g., a computer) readable medium or any type of medium suitable for storing electronic instructions and respectively coupled to a bus, including, but not limited to, any type of disk (including floppy disks, hard disks, optical disks, CD-ROMs, and magneto-optical disks), ROMs (Read-Only memories), RAMs (Random Access Memory, random access memories), EPROMs (Erasable Programmable Read-Only memories), EEPROMs (ELECTRICALLY ERASABLE PROGRAMMABLE READ-Only memories), flash memories, magnetic cards, or optical cards. That is, a readable medium includes any medium that stores or transmits information in a form readable by a device (e.g., a computer).

Those skilled in the art will appreciate that these computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing method to implement the disclosed aspects of the present invention by the processor of the computer or other programmable data processing method.

Those of skill in the art will appreciate that the various operations, methods, steps in the flow, acts, schemes, and alternatives discussed in the present invention may be alternated, altered, combined, or eliminated. Further, other steps, means, or steps in a process having various operations, methods, or procedures discussed herein may be alternated, altered, rearranged, disassembled, combined, or eliminated. Further, steps, measures, schemes in the prior art with various operations, methods, flows disclosed in the present invention may also be alternated, altered, rearranged, decomposed, combined, or deleted.

The foregoing description of the preferred embodiments of the application is not intended to limit the application to the precise form or details of construction and design disclosed, and claimed, such as the preferred embodiments of the application, but not limited to the specific form or design illustrated.

Claims (46)

1. A method performed by an entity for access and mobility management functions, the method comprising:

Receiving a message related to a handover required message from an entity for mobility management;

Transmitting a switching request message to a destination node; and

An acknowledgement message of the handover request message is received from the destination node,

Wherein the source auxiliary node and the destination node are implemented in the same network entity,

Wherein the handover request message includes a UE identity for identifying the UE,

Wherein the UE identity is allocated at the source and secondary nodes,

Wherein data forwarding for bearers terminated at the source and secondary nodes is performed intra-node.

2. The method of claim 1, wherein a handover required message is sent from a source home node to an entity for mobility management, the handover required message including the UE identity,

Wherein the UE identity comprises SgNB UE X application protocol, AP, ID, the SgNB UE X AP ID being used to identify the UE on the X2 interface in the source secondary node.

3. The method according to claim 2,

Wherein the source secondary node and the destination node correspond to the same network entity,

Wherein the handover required message includes Source NG-RAN Node to Target NG-RAN Node transparent container field from Source NG-RAN Node to destination NG-RAN Node, the Source NG-RAN Node to Target NG-RAN Node transparent container field is used for carrying the SgNB UE X AP ID, and

The handover request message includes Source NG-RAN Node to Target NG-RAN Node transparent container fields from Source NG-RAN Node to destination NG-RAN Node, where the Source NG-RAN Node to Target NG-RAN Node transparent container fields are used to carry the SgNB UE X AP ID.

4. The method according to claim 1,

Wherein a handover command message is sent from said entity for mobility management to the source host node.

5. The method according to claim 1,

Wherein the handover is an intersystem handover from an evolved packet system EPS to a 5G system 5 GS.

6. The method according to claim 1,

Wherein the source secondary node is associated with a source primary node in a dual connection.

7. The method according to claim 1,

Wherein the source and secondary nodes serve as the destination nodes for the handover.

8. A method performed by a destination node, the method comprising:

receiving a handover request message from an entity for access and mobility management functions; and

Sending an acknowledgement message of the handover request message to the entity for access and mobility management functions,

Wherein the source auxiliary node and the destination node are implemented in the same network entity,

Wherein the handover request message includes a UE identity for identifying the UE,

Wherein the UE identity is allocated at the source and secondary nodes,

Wherein data forwarding for bearers terminated at the source and secondary nodes is performed intra-node.

9. The method according to claim 8,

Wherein a handover required message is sent from the source master node to the entity for mobility management, said handover required message comprising said UE identity,

Wherein the UE identity comprises SgNB UE X application protocol, AP, ID, the SgNB UE X AP ID being used to identify the UE on the X2 interface in the secondary node.

10. The method according to claim 9, wherein the method comprises,

Wherein the source secondary node and the destination node correspond to the same network entity,

Wherein the handover required message includes Source NG-RAN Node to Target NG-RAN Node transparent container field from Source NG-RAN Node to destination NG-RAN Node, the Source NG-RAN Node to Target NG-RAN Node transparent container field is used for carrying the SgNB UE X AP ID, and

The handover request message includes Source NG-RAN Node to Target NG-RAN Node transparent container fields from Source NG-RAN Node to destination NG-RAN Node, where the Source NG-RAN Node to Target NG-RAN Node transparent container fields are used to carry the SgNB UE X AP ID.

11. The method according to claim 8,

Wherein a handover command message is sent from the entity for mobility management to the source master node.

12. The method according to claim 8,

Wherein the handover is an intersystem handover from an evolved packet system EPS to a 5G system 5 GS.

13. The method according to claim 8,

Wherein the source secondary node is associated with a source primary node in a dual connection.

14. The method according to claim 8,

Wherein the source and secondary nodes serve as the destination nodes for the handover.

15. A method performed by a source master node, the method comprising:

sending a handover required message to an entity for mobility management; and

Receiving a handover command message from the entity for mobility management;

wherein the source auxiliary node and the destination node are implemented in the same network entity,

Wherein the handover required message includes a UE identity for identifying the UE,

Wherein the UE identity is allocated at the source and secondary nodes,

Wherein data forwarding for bearers terminated at the source and secondary nodes is performed intra-node.

16. The method according to claim 15,

Wherein the UE identity comprises SgNB UE X application protocol, AP, ID, the SgNB UE X AP ID being used to identify the UE on the X2 interface in the secondary node.

17. The method according to claim 15,

The handover required message includes Source NG-RAN Node to Target NG-RAN Node transparent container field from Source NG-RAN Node to destination NG-RAN Node, where the Source NG-RAN Node to Target NG-RAN Node transparent container field is used to carry SgNB UE X AP ID.

18. The method according to claim 15,

Wherein the handover is an intersystem handover from an evolved packet system EPS to a 5G system 5 GS.

19. The method according to claim 15,

Wherein the source master node is associated with the source slave node in a dual connection.

20. The method according to claim 15,

Wherein the source and secondary nodes serve as the destination nodes for the handover.

21. A method performed by an entity for mobility management, the method comprising:

Receiving a message related to a handover required message from an entity for access and mobility management functions;

transmitting a switching request message to a target main node; and

Receiving an acknowledgement message of the handover request message from the destination host node,

Wherein the source node and the destination auxiliary node are implemented in the same network entity,

Wherein the handover request message includes a node identity and a UE identity of the source node,

Wherein the UE identity is assigned at the source node,

Wherein the data forwarding for the bearer terminating at the destination secondary node is performed in an intra-node manner.

22. The method according to claim 21,

Wherein a handover required message is sent from the source node to the entity for access and mobility management functions, the handover required message comprising a node identity of the source node and the UE identity;

Wherein a handover command message is sent from the entity for access and mobility management functions to the source node.

23. The method according to claim 21,

Wherein the destination secondary node and the source node correspond to the same network entity,

Wherein the handover required message includes a source evolved node to destination evolved node Source eNB to Target eNB transparent container field, the Source eNB to Target eNB transparent container field is configured to carry a node identifier of the source node and the UE identifier, and

The handover request message includes a source evolved node to destination evolved node Source eNB to Target eNB transparent container field, where the Source eNB to Target eNB transparent container field is configured to carry a node identifier of the source node and the UE identifier.

24. The method according to claim 21,

Wherein a secondary node addition request message is sent from the destination primary node to the destination secondary node,

Wherein the secondary node addition request message includes the UE identity.

25. The method according to claim 21,

Wherein the handover is an intersystem handover from the 5G system 5GS to the evolved packet system EPS.

26. The method according to claim 21,

Wherein the destination primary node is associated with the destination secondary node in a dual connection.

27. The method according to claim 21,

Wherein the source node serves as the destination secondary node for the handover.

28. A method performed by a destination master node, the method comprising:

receiving a handover request message from an entity for mobility management; and

Sending an acknowledgement message of the handover request message to the entity for mobility management,

Wherein the source node and the destination auxiliary node are implemented in the same network entity,

Wherein the handover request message includes a node identity of the source node and a UE identity,

Wherein the UE identity is assigned at the source node,

Wherein the data forwarding for the bearer terminating at the destination secondary node is performed in an intra-node manner.

29. The method of claim 28, wherein the method comprises,

Wherein a handover required message is sent from the source node to an entity for access and mobility management functions;

Wherein a handover command message is sent from the entity for access and mobility management functions to the source node.

30. The method of claim 28, wherein the method comprises,

Wherein the source node and the destination secondary node correspond to the same network entity,

Wherein a handover required message is sent from the source node to the entity for access and mobility management functions, the handover required message comprising a source evolved node to destination evolved node Source eNB to Target eNB transparent container field, the Source eNB to Target eNB transparent container field for carrying a node identity of the source node and the UE identity, and

The handover request message includes a source evolved node to destination evolved node Source eNB to Target eNB transparent container field, where the Source eNB to Target eNB transparent container field is configured to carry a node identifier of the source node and the UE identifier.

31. The method of claim 28, further comprising:

Sending a secondary node addition request message to the destination secondary node,

Wherein the secondary node addition request message includes the UE identity.

32. The method of claim 28, wherein the method comprises,

Wherein the handover is an intersystem handover from the 5G system 5GS to the evolved packet system EPS.

33. The method of claim 28, wherein the method comprises,

Wherein the destination primary node is associated with the destination secondary node in a dual connection.

34. The method of claim 28, wherein the method comprises,

Wherein the source node serves as the destination secondary node for the handover.

35. A method performed by a source node, the method comprising:

transmitting a handover required message to an entity for access and mobility management functions; and

A handover command message is received from the entity for access and mobility management functions,

Wherein the source node and the destination auxiliary node are implemented in the same network entity,

Wherein the handover required message includes a node identity of the source node and a UE identity,

Wherein the UE identity is assigned at the source node,

Wherein the data forwarding for the bearer terminating at the destination secondary node is performed in an intra-node manner.

36. The method according to claim 35, wherein the method comprises,

Receiving a secondary node addition request message from a destination primary node to the destination secondary node,

Wherein the secondary node addition request message includes the UE identity.

37. The method according to claim 35, wherein the method comprises,

Wherein the source node and the destination secondary node correspond to the same network entity,

Wherein a handover required message is sent from the source node to the entity for access and mobility management functions, the handover required message comprising a source evolved node to destination evolved node Source eNB to Target eNB transparent container field, the Source eNB to Target eNB transparent container field being used to carry a node identity of the source node and the UE identity.

38. The method according to claim 35, wherein the method comprises,

Wherein the handover is an intersystem handover from the 5G system 5GS to the evolved packet system EPS.

39. The method according to claim 35, wherein the method comprises,

Wherein a destination primary node is associated with the destination secondary node in a dual connection.

40. The method according to claim 35, wherein the method comprises,

Wherein the source node serves as the destination secondary node for the handover.

41. An entity for access and mobility management functions, comprising:

a memory configured to store instructions; and

A processor coupled with the memory and configured to execute the instructions to implement the method of any of claims 1-7.

42. A destination node, comprising:

a memory configured to store instructions; and

A processor coupled to the memory and configured to execute the instructions to implement the method of any of claims 8-14.

43. A source master node comprising:

a memory configured to store instructions; and

A processor coupled to the memory and configured to execute the instructions to implement the method of any of claims 15-20.

44. An entity for mobility management, comprising:

a memory configured to store instructions; and

A processor coupled to the memory and configured to execute the instructions to implement the method of any of claims 21-27.

45. A destination master node comprising:

a memory configured to store instructions; and

A processor coupled to the memory and configured to execute the instructions to implement the method of any of claims 28-34.

46. A source node, comprising:

a memory configured to store instructions; and

A processor coupled to the memory and configured to execute the instructions to implement the method of any of claims 35-40.