# US 12,764,648 B2 · Method and apparatus for selecting network slice admission control function > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,764,648 B2 - Document ID: US12764648B2 - Status: Granted - Kind: B2 - Application number: 18/681,832 - Filed: 2021-08-06 - Published: 2024-10-17 - Granted: 2026-10-13 - Earliest claimed: 2021-08-06 - Assignees: Beijing Xiaomi Mobile Software Co., Ltd. - Applicants: Beijing Xiaomi Mobile Software Co., Ltd. - Inventors: Wei Hong; Yang Shen - Web page: https://patentgrep.com/patent/US12764648B2 ## CPC - H04W 48/18: Selecting a network or a communication service - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract The present disclosure provides a method and an apparatus for selecting a network slice admission control function (NSACF). The method includes selecting an NSACF for a network slice based on service area information of the NSACF. The NSACF selected is used to monitor a number of created protocol data unit (PDU) sessions of the network slice. ## Claims ### Claim 1 A method for selecting a network slice admission control function (NSACF), performed by a first session management function (SMF) and comprising: selecting an NSACF for a network slice based on service area information of the NSACF after receiving a protocol data unit (PDU) session creation request or a PDU session update request from a user equipment (UE), wherein the NSACF selected is used to monitor a number of created PDU sessions of the network slice; sending a session number availability check and update request to the NSACE selected, wherein the session number availability check and update request comprises single-network slice selection assistance information (S-NSSAI) and a first update flag, and the first update flag indicates to increase the number of the created PDU sessions; receiving a session number availability check and update response message from the NSACF selected; and performing a PDU session creation procedure or a PDU session update procedure, and returning a session creation acceptance message or a session update acceptance message to the UE in case the session number availability check and update response message indicates that availability check is successful; or, returning a session creation rejection message or a session update rejection message to the UE in case the session number availability check and update response message indicates that availability check is failed. ### Claim 2 (depends on 1) The method according to claim 1, wherein the service area information comprises any one or more of: a tracking area identity list; service area information of the first SMF; or service area information of one or more user plane functions (UPFs) controlled by the first SMF. ### Claim 3 (depends on 1) The method according to claim 1, wherein selecting the NSACF for the network slice comprises: maintaining the NSACF selected to be selected for the network slice in case an NSACF has been selected for the network slice and the service area information of the NSACF indicates that the NSACF selected is capable of being used for the network slice. ### Claim 4 (depends on 1) The method according to claim 1, wherein selecting the NSACF for the network slice comprises: selecting an NSACF for the network slice from a plurality of NSACFs selected in case the plurality of NSACFs have been selected for the network slice and service area information of the plurality of NSACFs indicates that the plurality of the NSACFs selected are capable of being used for the network slice. ### Claim 5 (depends on 4) The method according to claim 4, wherein selecting the NSACF for the network slice from the plurality of the NSACFs selected comprises: selecting an NSACF for the network slice from the plurality of the NSACFs selected based on service capability of the NSACF; wherein the service capability comprises at least one of: a first service capability that supports monitoring a number of registered UEs of the network slice, or a second service capability that supports monitoring a number of the created PDU sessions of the network slice. ### Claim 6 (depends on 1) The method according to claim 1, wherein selecting the NSACF for the network slice comprises: selecting an NSACF not belonging to one or more NSACFs selected for the network slice in case the one or more NSACFs have been selected for the network slice and service area information of the one or more NSACFs indicates that the one or more NSACFs selected are not used for the network slice. ### Claim 7 (depends on 1) The method according to claim 1, wherein in case an operator service area policy exists, selecting the NSACF for the network slice comprises: selecting an NSACF for the network slice based on the service area information of the NSACF and the operator service area policy; wherein the operator service area policy comprises a specific rule formulated by an operator to perform NSACF selection based on the service area information. ### Claim 8 (depends on 7) The method according to claim 7, wherein the operator service area policy is pre-configured in at least one of the first SMF and a network repository function (NRF). ### Claim 9 (depends on 8) The method according to claim 8, wherein selecting the NSACF for the network slice comprises: selecting an NSACF for the network slice from registered NSACFs of the NRF, wherein the NRF stores configuration information of the registered NSACFs, and the configuration information comprises the S-NSSAI and service area information of the registered NSACFs. ### Claim 10 (depends on 1) The method according to claim 1, wherein selecting the NSACF for the network slice comprises: selecting an NSACF for the network slice from pre-configured NSACFs of the first SMF, wherein the first SMF stores configuration information of the pre-configured NSACFs, and the configuration information comprises the S-NSSAI) and service area information of the pre-configured NSACFs. ### Claim 11 (depends on 1) The method according to claim 1, further comprising: receiving a PDU session release request from thea UE via an AMF, wherein the PDU session release request carries S-NSSAIs; sending a session number availability check and update request to the NSACF selected for the network slice identified by the S-NSSAIs in response to the PDU session release request, wherein the session number availability check and update request comprises the S-NSSAIs and a second update flag, and the second update flag indicates to reduce the number of the created PDU sessions; and receiving a session number availability check and update response message from the NSACF selected, and performing PDU session release according to the session number availability check and update response message. ### Claim 12 A communication device being a first session management function (SMF), comprising: a transceiver; a memory; and a processor, connected to the transceiver and the memory and configured, by executing computer-executable instructions on the memory, to control wireless signal transmission and reception of the transceiver and to: select a network slice admission control function NSACF for a network slice based on service area information of the NSACF after receiving a protocol data unit (PDU) session creation request or a PDU session update request from a user equipment (UE), wherein the NSACF selected is used to monitor a number of created PDU sessions of the network slice; send a session number availability check and update request to the NSACF selected, wherein the session number availability check and update request comprises single-network slice selection assistance information (S-NSSAI) and a first update flag, and the first update flag indicates to increase the number of the created PDU sessions; receive a session number availability check and update response message from the NSACF selected; and perform a PDU session creation procedure or a PDU session update procedure, and return a session creation acceptance message or a session update acceptance message to the UE in case the session number availability check and update response message indicates that availability check is successful; or, return a session creation rejection message or a session update rejection message to the UE in case the session number availability check and update response message indicates that availability check is failed. ### Claim 13 (depends on 12) The communication device according to claim 12, wherein the service area information comprises any one or more of: a tracking area identity list; service area information of the first SMF; or service area information of one or more user plane functions (UPFs) controlled by the first SMF. ### Claim 14 (depends on 12) The communication device according to claim 12, wherein the processor is further configured to: maintain the NSACF selected to be selected for the network slice in case an NSACF has been selected for the network slice and the service area information of the NSACF indicates that the NSACF selected is capable of being used for the network slice. ### Claim 15 (depends on 12) The communication device according to claim 12, wherein the processor is further configured to: select an NSACF for the network slice from a plurality of NSACFs selected in case the plurality of NSACFs have been selected for the network slice and service area information of the plurality of NSACFs indicates that the plurality of the NSACFs selected are capable of being used for the network slice. ### Claim 16 (depends on 15) The communication device according to claim 15, wherein the processor is further configured to: select an NSACF for the network slice from the plurality of the NSACFs selected based on service capability of the NSACF; wherein the service capability comprises at least one of: a first service capability that supports monitoring a number of registered UEs of the network slice, or a second service capability that supports monitoring a number of the created PDU sessions of the network slice. ### Claim 17 (depends on 12) The communication device according to claim 12, wherein the processor is further configured to: select an NSACF not belonging to one or more NSACFs selected for the network slice in case the one or more NSACFs have been selected for the network slice and service area information of the one or more NSACFs indicates that the one or more NSACFs selected are not used for the network slice. ### Claim 18 (depends on 12) The communication device according to claim 12, wherein the processor is further configured to: in case an operator service area policy exists, select an NSACF for the network slice based on the service area information of the NSACF and the operator service area policy; wherein the operator service area policy comprises a specific rule formulated by an operator to perform NSACF selection based on the service area information. ### Claim 19 (depends on 12) The communication device according to claim 12, wherein the processor is further configured to: select an NSACF for the network slice from pre-configured NSACFs of the first SMF, wherein the first SMF stores configuration information of the pre-configured NSACFs, and the configuration information comprises the S-NSSAI and service area information of the pre-configured NSACFs. ### Claim 20 (depends on 12) The communication device according to claim 12, wherein the processor is further configured to: receive a PDU session release request from the UE via an AMF, wherein the PDU session release request carries S-NSSAIs; send a session number availability check and update request to the NSACF selected for the network slice identified by the S-NSSAIs in response to the PDU session release request, wherein the session number availability check and update request comprises the S-NSSAIs and a second update flag, and the second update flag indicates to reduce the number of the created PDU sessions; and receive a session number availability check and update response message from the NSACF selected, and performing PDU session release according to the session number availability check and update response message.