# US 11,910,460 B2 · Assistance information for SPCell selection > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,910,460 B2 - Document ID: US11910460B2 - Status: Granted - Kind: B2 - Application number: 17/880,135 - Filed: 2022-08-03 - Published: 2022-11-24 - Granted: 2024-02-20 - Earliest claimed: 2018-02-28 - Assignees: Telefonaktiebolaget LM Ericsson (publ) - Applicants: Telefonaktiebolaget LM Ericsson (publ) - Inventors: Angelo Centonza; Matteo Fiorani - Web page: https://patentgrep.com/patent/US11910460B2 ## CPC - H04W 48/14: using user query {or user detection} - H04W 76/18: Management of setup rejection or failure - H04L 41/0668: by dynamic selection of recovery network elements, e.g. replacement by the most appropriate element after failure - H04W 72/21: in the uplink direction of a wireless link, i.e. towards the network - H04W 76/19: Connection re-establishment - H04W 76/27: Transitions between radio resource control [RRC] states - H04W 88/06: adapted for operation in multiple networks {or having at least two operational modes}, e.g. multi-mode terminals - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Exemplary embodiments include methods performed by a central unit, CU, of a base station, for selecting a special cell, SpCell, to be used by a first distributed unit, DU, of the base station for serving a user equipment, UE. Such embodiments can include sending, to the first DU, a first request comprising an identity of a first cell, served by the first DU, as a preferred SpCell for the UE; and identities of one or more second cells served by the first DU. Such embodiments can also include receiving, from the first DU, a first response comprising a first indication that the first DU cannot configure the first cell as an SpCell for the UE, and a second indication that the first DU can configure zero or more third cells as an SpCell for the UE. ## Claims ### Claim 1 A method, performed by a central unit (CU) of a base station, for selecting a special cell (SpCell) to be used by a first distributed unit (DU) of the base station for serving a user equipment (UE) the method comprising: sending, to the first DU, a first request comprising: an identity of a first cell served by the first DU, as a preferred SpCell for the UE; and identities of one or more second cells served by the first DU, as candidate SpCells for the UE; and receiving, from the first DU, a first response comprising: a first indication that the first DU cannot configure the first cell as an SpCell for the UE; and a second indication of which of the second cells that the first DU can configure as an SpCell for the UE. ### Claim 2 (depends on 1) The method of claim 1, further comprising: receiving radio signal measurements relating to a plurality of cells associated with one or more DUs including the first DU; and selecting the first cell and the one or more second cells from the plurality of cells based on the radio signal measurements. ### Claim 3 (depends on 2) The method of claim 2, further comprising: selecting a further first cell and one or more further second cells, served by a second DU, from the plurality of cells based on the radio signal measurements; sending, to the second DU, a second request comprising an identity of the further first cell and identities of the further second cells; receiving, from the second DU, a second response comprising: a further first indication that the second DU cannot configure the further first cell as an SpCell for the UE; and a further second indication of which of the further second cells that the second DU can configure as an SpCell for the UE. ### Claim 4 (depends on 3) The method of claim 3, wherein the further second indication comprises: when the second DU cannot configure any of the further second cells as an SpCell for the UE, an indication that the second DU cannot configure any of the further second cells as an SpCell for the UE; and when the second DU can configure at least one of the further second cells as an SpCell for the UE, identities of the further second cells that the second DU can configure as an SpCell for the UE. ### Claim 5 (depends on 4) The method of claim 4, further comprising selecting an SpCell for the UE from a combination of the following: the second cells identified by the first response and the further second cells identified by the second response. ### Claim 6 (depends on 1) The method of claim 1, wherein the second indication comprises: when the first DU cannot configure any of the second cells as an SpCell for the UE, an indication that the first DU cannot configure any of the second cells as an SpCell for the UE; and when the first DU can configure at least one of the second cells as an SpCell for the UE, identities of the second cells that the first DU can configure as an SpCell for the UE. ### Claim 7 (depends on 6) The method of claim 6, further comprising selecting an SpCell for the UE from the second cells identified by the second indication. ### Claim 8 (depends on 6) The method of claim 6, wherein: the identities of the second cells are received in an ordered list; and the order of the list is based on one or more operating conditions of the first DU. ### Claim 9 (depends on 8) The method of claim 8, wherein the one or more operating conditions comprise one or more of: first DU load conditions; availability of first DU resources associated with the respective second cells; or location of the UE within first DU coverage areas associated with the respective second cells. ### Claim 10 (depends on 8) The method of claim 8, wherein: the first response also includes a cause value indicating why the first DU cannot configure the first cell as an SpCell for the UE; and the cause value is related to the one or more operating conditions of the first DU. ### Claim 11 (depends on 8) The method of claim 8, wherein selecting the SpCell for the UE from the second cells is based on the list order and radio signal measurements relating to a plurality of cells associated with one or more DUs including the first DU. ### Claim 12 (depends on 1) The method of claim 1, wherein the one or more second cells comprise one of the following: candidate SpCells for the UE, and candidate secondary cells (SCells) for the UE. ### Claim 13 (depends on 1) The method of claim 1, wherein the first request and the first response comprise one of the following pairs of messages: a UE context setup request and a UE context setup failure; and a UE context modification request and a UE context modification failure. ### Claim 14 A central unit (CU) of a base station, configured to select a special cell (SpCell) to be used by a first distributed unit (DU) of the base station for serving a user equipment (UE), the CU comprising: a non-transitory memory storing computer-executable instructions; and processing circuitry coupled to the non-transitory memory and configured to execute the stored instructions, wherein execution of the stored instructions causes the CU to: send, to the first DU, a first request comprising: an identity of a first cell served by the first DU, as a preferred SpCell for the UE; and identities of one or more second cells served by the first DU, as candidate SpCells for the UE; and receive, from the first DU, a first response comprising: a first indication that the first DU cannot configure the first cell as an SpCell for the UE; and a second indication of which of the second cells that the first DU can configure as an SpCell for the UE. ### Claim 15 (depends on 14) The CU of claim 14, wherein the second indication comprises: when the first DU cannot configure any of the second cells as an SpCell for the UE, an indication that the first DU cannot configure any of the second cells as an SpCell for the UE; and when the first DU can configure at least one of the second cells as an SpCell for the UE, identities of the second cells that the first DU can configure as an SpCell for the UE. ### Claim 16 (depends on 15) The CU of claim 15, wherein: the identities of the second cells are received in an ordered list; and the order of the list is based on one or more operating conditions of the first DU. ### Claim 17 (depends on 16) The CU of claim 16, wherein: the first response also includes a cause value indicating why the first DU cannot configure the first cell as an SpCell for the UE; and the cause value is related to the one or more operating conditions of the first DU. ### Claim 18 (depends on 14) The CU of claim 14, wherein the first request and the first response comprise one of the following pairs of messages: a UE context setup request and a UE context setup failure; and a UE context modification request and a UE context modification failure. ### Claim 19 A non-transitory computer-readable medium storing computer-executable instructions that, when executed by processing circuitry comprising a central unit (CU) of a base station, configure the CU to: send, to a first distributed unit (DU), a first request comprising: an identity of a first cell served by the first DU, as a preferred special cell (SpCell) for the UE; and identities of one or more second cells served by the first DU, as candidate SpCells for the UE; and receive, from the first DU, a first response comprising: a first indication that the first DU cannot configure the first cell as an SpCell for the UE; and a second indication of which of the second cells that the first DU can configure as an SpCell for the UE.