US-20260129527-A1 - DUAL CONNECTIVITY-BASED SECONDARY CELL GROUP CHANGE

Abstract

Example embodiments of the present disclosure are directed to a dual connectivity-based (DC-based) secondary cell group change. A method comprises receiving, from a first network device, an indication to initiate a dual connectivity-based secondary cell group change; adding a first cell into a secondary cell group based on the indication, the first cell being provided by the first network device and serving the user device; deactivating a master cell group including the first cell; receiving, from the first network device, an inter-secondary node switching configuration for the dual connectivity-based secondary cell group change; and switching from the first cell to a second cell based on the inter-secondary node switching configuration, the second cell being provided by a second network device and included in a target secondary cell group.

Inventors

• Halit Murat GÜRSU
• Srinivasan Selvaganapathy
• Jedrzej Stanczak
• Krzysztof Kordybach
• Andres Arjona

Assignees

• NOKIA TECHNOLOGIES OY

Dates

Publication Date

20260507

Application Date

20241107

Claims (20)

1. 1 . A user device comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the user device operating in a single connectivity mode at least to: receive, from a first network device, an indication to initiate a dual connectivity-based secondary cell group change; add a first cell into a secondary cell group based on the indication, the first cell being provided by the first network device and serving the user device; deactivate a master cell group including the first cell; receive, from the first network device, an inter-secondary node switching configuration for the dual connectivity-based secondary cell group change; and switch from the first cell to a second cell based on the inter-secondary node switching configuration, the second cell being provided by a second network device and included in a target secondary cell group.
2. 2 . The user device of claim 1 , wherein the instructions, when executed by the at least one processor, further cause the user device to: maintain a packet data convergence protocol entity for the master cell group.
3. 3 . The user device of claim 1 , wherein the instructions, when executed by the at least one processor, further cause the user device to: perform, based on the indication, at least one of: resetting at least one of a radio link control entity, a media access control entity or a physical layer entity for the master cell group; stopping at least one of radio link monitoring or radio link failure detection for the master cell group; stopping beam failure detection for the master cell group; stopping a measurement on the master cell group; triggering a re-establishment procedure based on detecting a radio link failure for the secondary cell group; or converting a signaling radio bearer for the master cell group to a split bearer for both the master cell group and the secondary cell group, wherein a part of the split bearer corresponding to the master cell group is disabled.
4. 4 . The user device of claim 1 , wherein the instructions, when executed by the at least one processor, further cause the user device to: send, to the first network device, a measurement report identifying the second cell, wherein the indication is received from the first network device after sending the measurement report.
5. 5 . The user device of claim 1 , wherein the indication is received via radio resource control signaling.
6. 6 . The user device of claim 1 , wherein the indication is carried in a radio resource control reconfiguration message.
7. 7 . The user device of claim 6 , wherein the instructions, when executed by the at least one processor, further cause the user device to: responsive to receiving the radio resource control reconfiguration message, perform a random access procedure with the first network device to convert the first cell to a primary secondary cell; and send a radio resource control reconfiguration complete message to the first network device.
8. 8 . The user device of claim 6 , wherein the instructions, when executed by the at least one processor, further cause the user device to: responsive to receiving the radio resource control reconfiguration message, send a radio resource control reconfiguration complete message to the first network device, without a random access procedure with the first network device to convert the first cell to a primary secondary cell.
9. 9 . The user device of claim 1 , wherein the inter-secondary node switching configuration comprises at least one secondary cell group configuration of at least one candidate cell, the at least one candidate cell including the second cell.
10. 10 . The user device of claim 1 , wherein the inter-secondary node switching configuration is sent to the user device via radio resource control signaling.
11. 11 . The user device of claim 1 , wherein the instructions, when executed by the at least one processor, further cause the user device to: replace a secondary cell group configuration of the second cell with a further secondary cell group configuration of a further cell provided by a further network device, wherein the further cell is the first cell or a third cell.
12. 12 . A first network device comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first network device at least to: receive, from a user device operating in a single connectivity mode, a measurement report identifying a second cell provided by a second network device; determine, based on the measurement report, to initiate a dual connectivity-based secondary cell group change for the user device; send, to the user device, an indication to initiate the dual connectivity-based secondary cell group change; and send, to the user device, an inter-secondary node switching configuration for the dual connectivity-based secondary cell group change.
13. 13 . The first network device of claim 12 , wherein the determining is based on a quality of service requirement of the user device.
14. 14 . The first network device of claim 12 , wherein the instructions that, when executed by the at least one processor, further cause the first network device to: enter the user device from the single connectivity mode to a dual connectivity mode, based on the determining.
15. 15 . The first network device of claim 12 , wherein the instructions that, when executed by the at least one processor, further cause the first network device to: add a first cell into a secondary cell group of the user device based on the determining, the first cell being provided by the first network device and serving the user device; and disable a master cell group of the user device including the first cell.
16. 16 . The first network device of claim 12 , wherein the instructions that, when executed by the at least one processor, further cause the first network device to: send, to the second network device, a request for secondary node addition, the request indicating that the secondary node addition is used for the dual connectivity-based secondary cell group change; and receive, from the second network device, a response to the request, wherein the inter-secondary node switching configuration is sent to the user device after receiving the response.
17. 17 . The first network device of claim 16 , wherein the response includes a secondary cell group configuration of the second cell.
18. 18 . The first network device of claim 16 , wherein the request further indicates that a master node terminated bearer is to be used for the user device and a secondary cell group bearer is to be allocated by the second network device for the master node terminated bearer.
19. 19 . The first network device of claim 12 , wherein the inter-secondary node switching configuration comprises at least one secondary cell group configuration of at least one candidate cell, the at least one candidate cell including the second cell.
20. 20 . A second network device comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second network device at least to: receive, from a first network device, a request for secondary node addition, the request indicating that the secondary node addition is used for a dual connectivity-based secondary cell group change of a user device; and determine, based on the request, that a master cell group is to be deactivated by the user device for the dual connectivity-based secondary cell group change.

Description

FIELD Various example embodiments generally relate to the field of telecommunication and in particular, to methods, devices, apparatuses and computer readable storage medium for a dual connectivity-based (DC-based) secondary cell group change. BACKGROUND When user equipment (UE) moves from a coverage area of one cell to another cell, a serving cell change needs to be performed at some time point. Lower-layer triggered mobility (LTM), also known as Layer 1 (L1)/Layer 2 (L2) based inter-cell mobility, has been introduced to enable a serving cell change via L1/L2 signaling. The LTM helps to reduce latency, overhead and interruption time during handover. SUMMARY In a first aspect, there is provided a user device. The user device comprises: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the user device operating in a single connectivity mode at least to: receive, from a first network device, an indication to initiate a dual connectivity-based secondary cell group change; add a first cell or a second cell into a secondary cell group based on the indication, the first cell being provided by the first network device and serving the user device, and the second cell being provided by the second network device; and deactivate a master cell group including the first cell. In a second aspect, there is provided a first network device. The first network device comprises: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first network device at least to: receive, from a user device operating in a single connectivity mode, at least one measurement related to a second cell provided by a second network device; determine, based on the at least one measurement, to initiate a dual connectivity-based secondary cell group change for the user device; send, to the user device, an indication to initiate the dual connectivity-based secondary cell group change; and enter the user device from the single connectivity mode to a dual connectivity mode, based on the determining. In a third aspect, there is provided a second network device. The second network device comprises: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second network device at least to: receive, from a first network device, a request for secondary node addition, the request indicating that the secondary node addition is used for a dual connectivity-based secondary cell group change of a user device; and determine, based on the request, that a master cell group is to be deactivated by the user device for the dual connectivity-based secondary cell group change. In a fourth aspect, there is provided a method. The method comprises: receiving, from a first network device, an indication to initiate a dual connectivity-based secondary cell group change; adding a first cell or a second cell into a secondary cell group based on the indication, the first cell being provided by the first network device and serving the user device, and the second cell being provided by the second network device; and deactivating a master cell group including the first cell. In a fifth aspect, there is provided a method. The method comprises: receiving, from a user device operating in a single connectivity mode, at least one measurement related to a second cell provided by a second network device; determining, based on the at least one measurement, to initiate a dual connectivity-based secondary cell group change for the user device; sending, to the user device, an indication to initiate the dual connectivity-based secondary cell group change; and entering the user device from the single connectivity mode to a dual connectivity mode, based on the determining. In a sixth aspect, there is provided a method. The method comprises: receiving, from a first network device, a request for secondary node addition, the request indicating that the secondary node addition is used for a dual connectivity-based secondary cell group change of a user device; and determining, based on the request, that a master cell group is to be deactivated by the user device for the dual connectivity-based secondary cell group change. In a seventh aspect, there is provided a first apparatus. The first apparatus comprises means for receiving, from a first network device, an indication to initiate a dual connectivity-based secondary cell group change; means for adding a first cell or a second cell into a secondary cell group based on the indication, the first cell being provided by the first network device and serving the user device, and the second cell being provided by the second network device; and means for deactivating a master cell group including the first cell. In an eighth aspect, there is provided a second apparatus. The second apparatus comprises means for receiving, from a user devic