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EP-4434262-B1 - MANAGING CELL GROUP CONFIGURATIONS FOR CONDITIONAL SECONDARY NODE PROCEDURES

EP4434262B1EP 4434262 B1EP4434262 B1EP 4434262B1EP-4434262-B1

Inventors

  • HSIEH, JING
  • WU, CHIH-HSIANG

Dates

Publication Date
20260513
Application Date
20230106

Claims (14)

  1. A method implemented in a network node in a radio access network, RAN, the network node operating as a candidate secondary node, C-SN, for managing a conditional procedure that involves a user equipment, UE, the C-SN, and another network node operating as a master node, MN, the method comprising: transmitting (904), by the C-SN to the MN, a message including a list of candidate cells of the C-SN for addition or modification, the list including: at least one candidate cell for addition, at least one candidate cell for modification, and for each candidate cell of the candidate cells, a respective conditional configuration associated with a condition to be satisfied for the UE to connect to the candidate cell.
  2. The method of claim 1, wherein the message is CG-CandidateList.
  3. The method of claim 1 or 2, wherein the message includes cg- CandidateToAddModList or cg-Candidate ToAddModList-r1 7, or wherein the message includes cg-CandidateToReleaseList or cg-CandidateToReleaseList-r17.
  4. The method of any of the preceding claims, wherein: the list is an updated list; the method further comprising: transmitting, by a core network, CN, to the MN and prior to transmitting the message, an initial list of candidate cells.
  5. The method of claim 4, wherein the initial list of candidate cells is included in an SNAddition Request Ack message.
  6. The method of claim 4 or 5, further comprising: receiving a request from the MN to update the initial list, the request including at least one of (i) a measurement related to the one or more candidate cells or (ii) an indication of a maximum number of cells that the C-SN is permitted to configure as candidate cells; generating the updated list in response to the request.
  7. The method of claim 6, wherein the message is one of: (i) SNAddition Request Ack, (ii) NG-RAN node Configuration Update, or (iii) E-UTRA - NR Cell Resource Coordination Request.
  8. The method of claim 1, wherein: the list includes, for each candidate cell of the one or more candidate cells, a cell identifier of the candidate cell, and the conditional configuration for the candidate cell.
  9. A method implemented in a network node, operating as a master node, MN, for managing a conditional procedure that involves a user equipment, UE, the MN, and a network node operating as a C-SN, the method comprising: receiving (904), by the MN from the C-SN, an information element for conveying a list of candidate cells of the C-SN for addition or modification, the list including: at least one candidate cell for addition at least one candidate cell for modification, and for each candidate cell of the candidate cells, a respective conditional configuration associated with a condition to be satisfied for the UE to connect to the candidate cell.
  10. The method of claim 9, further comprising: receiving, by the MN from the C-SN, an indication of an update to the list; and updating, by the MN, the stored one or more conditional configurations in accordance with the update.
  11. The method of claim 10, further comprising: determining, by the processing hardware after receiving the list and prior to receiving the indication of the update, to update the list; and transmitting, by the processing hardware to the C-SN, a request to update the list.
  12. The method of claim 10 or 11, wherein the information is one of: (i) is cg-CandidateToAdoModList, (ii) cg-CandidateToAdoModList-r 1 7 (iii) cg-CandidateToReleaseList, or (iv) cg-CandidateToReleaseList-r17.
  13. The method of any of claims 9-12, further comprising: storing, by the MN, the one or more conditional configurations corresponding to the one or more candidate cells
  14. A network node comprising: a transceiver; and processing hardware configured to implement a method according to any one of the preceding claims.

Description

FIELD OF THE DISCLOSURE This disclosure relates generally to wireless communications and, more particularly, to managing conditional configurations for multi-connectivity such as conditional secondary node addition or change procedures. BACKGROUND This background description is provided for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. In telecommunication systems, a user equipment (UE) sometimes can concurrently utilize resources of multiple radio access network (RAN) nodes, such as base stations or components of a distributed base station, interconnected by a backhaul. When these network nodes support different radio access technologies (RATs), this type of connectivity is referred to as Multi-Radio Dual Connectivity (MR-DC). When a UE operates in MR-DC, one base station operates as a master node (MN) that covers a primary cell (PCell), and the other base station operates as a secondary node (SN) that covers a primary secondary cell (PSCell). The UE communicates with the MN (via the PCell) and the SN (via the PSCell). In other scenarios, the UE transfers a wireless connection from one base station to another base station. For example, a serving base station can determine to hand the UE over to a target base station and initiate a handover procedure. 3GPP specification TS 37.340 v16.6.0 describes procedures for a UE to add or change an SN in DC scenarios. These procedures involve messaging (e.g., RRC signaling and preparation) between radio access network (RAN) nodes. This messaging generally causes latency, which in turn increases the probability that the SN addition or SN change procedure will fail. These legacy procedures, which do not involve conditions that are checked at the UE, can be referred to as "immediate" SN addition and SN change procedures. More recently, for both SN or PSCell addition/change, "conditional" procedures have been considered (i.e., conditional SN or PSCell addition/change). Unlike the "immediate" procedures discussed above, these procedures do not add or change the SN or PSCell, or perform the handover, until the UE determines that a condition is satisfied. As used herein, the term "condition" may refer to a single, detectable state or event (e.g., a particular signal quality metric exceeding a threshold), or to a logical combination of such states or events (e.g., "Condition A and Condition B," or "(Condition A or Condition B) and Condition C", etc.). To configure a conditional procedure, the RAN provides the condition to the UE, along with a configuration (e.g., one or more random-access preambles, etc.) that will enable the UE to communicate with the appropriate base station, or via the appropriate cell, when the condition is satisfied. For a conditional addition of a base station as an SN or a candidate cell as a PSCell, for example, the RAN provides the UE with a condition to be satisfied before the UE can add that base station as the SN or that candidate cell as the PSCell, and a configuration that enables the UE to communicate with that base station or PSCell after the condition has been satisfied. In the immediate PSCell addition or change procedure, the RAN (i.e., MN or SN) transmits an RRC reconfiguration message including multiple configuration parameters to the UE and the UE attempts to connect to a (target) PSCell configured by the RRC reconfiguration message. After the UE successfully connects to the SN via the PSCell, the UE communicates with the SN on the PSCell by using the multiple configuration parameters and security key(s) associated to the PSCell and derived from one or more security configuration parameters in the RRC reconfiguration message. The SN also derives security key(s) that match the security key(s) derived from the UE. After the UE successfully connects to the PSCell, the RAN (e.g., the SN) communicates data with the UE by using the matching security key(s) and the multiple configuration parameters. In some cases, a candidate SN (C-SN) provides multiple candidate configurations when, for example, multiple candidate PSCells are available. When the MN completes the preparation for a conditional SN procedure (e.g., conditional SN addition or conditional SN cell change), the MN at this time cannot determine which candidate secondary cell the UE will connect to in the future. Moreover, because the UE connects to the secondary cell only subject to the fulfillment of one or more conditions, the MN cannot determine whether the UE will even connect to any of the candidate cells in the future. Recently, 3GPP has discussed methods for exchanging information related to C-SN configurations between the C-SN and the MN. As one example, the C-SN can tran