# US 2019/0320318 A1 · Handling radio link failure in a narrow bandwidth internet of things control plane > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0320318 A1 - Document ID: US20190320318A1 - Status: Published application - Kind: A1 - Application number: 16/347,660 - Filed: 2017-11-02 - Published: 2019-10-17 - Earliest claimed: 2016-11-07 - Assignees: Telefonaktiebolaget LM Ericsson (publ) - Applicants: Telefonaktiebolaget LM Ericsson (publ) - Inventors: Vesa LEHTOVIRTA; Christine JOST; Monica WIFVESSON - Web page: https://patentgrep.com/patent/US20190320318A1 ## CPC - H04L 63/205: {involving negotiation or determination of the one or more network security mechanisms to be used, e.g. by negotiation between the client and the server or between peers or by selection according to the capabilities of the entities involved (negotiation of communication capabilities H04L69/24)} - H04W 4/70: Services for machine-to-machine communication [M2M] or machine type communication [MTC] - H04W 12/041: Key generation or derivation - H04W 12/106: Packet or message integrity - H04W 12/108: Source integrity - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract A method of operating a user equipment, UE, includes establishing a radio resource control, RRC, connection with a base station, following establishment of the RRC connection, sending an indication of a security capability of the UE to the base station, receiving a non-access stratum, NAS, message, from the base station, wherein the NAS message identifies a selected security algorithm, and generating the access stratum security key to be used with the selected security algorithm. ## Claims ### Claim at position 1 1-48. (canceled) ### Claim 49 A method of operating a user equipment, UE, comprising: establishing a radio resource control, RRC, connection with a base station; following establishment of the RRC connection, sending an indication of a security capability of the UE to the base station; receiving a non-access stratum, NAS, message, from the base station, wherein the NAS message identifies a selected security algorithm; and generating the access stratum security key to be used with the selected security algorithm. ### Claim 50 (depends on 49) The method of claim 49, wherein the selected security algorithm is for protecting access stratum communications between the UE and base station. ### Claim 51 (depends on 50) The method of claim 50, further comprising: using the access stratum security key and the selected security algorithm to protect access stratum communications with the base station. ### Claim 52 (depends on 49) The method of claim 49, wherein the NAS message comprises a NAS security mode command. ### Claim 53 (depends on 49) The method of claim 49, wherein the base station comprises an eNodeB. ### Claim 54 (depends on 49) The method of claim 49, wherein the selected security algorithm comprises an integrity algorithm. ### Claim 55 (depends on 49) The method of claim 49, wherein the access stratum security key comprises an RRC message integrity key, Krrc_int. ### Claim 56 (depends on 49) The method of claim 49, wherein sending the indication of the security capability of the UE to the base station comprises sending a request to the base station, the request including the indication of the security capability of the UE. ### Claim 57 (depends on 56) The method of claim 56, wherein the request comprises an Attach request. ### Claim 58 (depends on 49) The method of claim 49, further comprising: generating a base station key KeNB; wherein generating the access stratum security key comprises generating the access stratum security key using the base station key KeNB and the selected integrity algorithm identifier. ### Claim 59 (depends on 58) The method of claim 58, further comprising: generating an RRC integrity token using the selected security algorithm and the access stratum key; and in response to a link failure between the UE and the source base station, transmitting the RRC integrity token to a target base station. ### Claim 60 (depends on 59) The method of claim 59, wherein the base station key KeNB and the access stratum security key are generated prior to the link failure. ### Claim 61 (depends on 59) The method of claim 59, wherein transmitting the RRC integrity token to the target base station comprises transmitting the integrity token in an RRC ConnRe-est Request message. ### Claim 62 (depends on 61) The method of claim 61, further comprising: receiving an RRC ConnRe-est Setup message in response to the RRC ConnRe-est Request message; and in response to receiving the RRC ConnRe-est Setup message, transmitting an NAS Data protocol data unit (PDU) to the target base station. ### Claim 63 (depends on 49) A computer program product comprising a non-transitory computer readable medium storing program code that when executed by a processor of the UE causes the UE to perform operations of the method of claim 49. ### Claim 64 (depends on 49) A UE adapted to perform the method of claim 49. ### Claim 65 A UE comprising: a transceiver; at least one processor coupled to the transceiver; and at least one memory coupled to the at least one processor and storing program code that when executed by the at least one processor causes the at least one processor to perform operations comprising: establishing a radio resource control, RRC, connection with a base station; following establishment of the RRC connection, sending an indication of a security capability of the UE to the base station; receiving a non-access stratum, NAS, message, from the base station, wherein the NAS message identifies a selected security algorithm; and generating the access stratum security key to be used with the selected security algorithm. ### Claim 66 A method of operating a network node of a cellular radio access network, RAN, the method comprising: establishing a radio resource control, RRC, connection with a user equipment, UE; following establishment of the RRC connection, receiving an indication of a security capability of the UE from the UE; generating a list of security algorithms supported by the network node; transmitting the list of supported security algorithms to a core network node; receiving, from the core network node, a selected security algorithm; and sending the selected security algorithm to the UE. ### Claim 67 A network node comprising: a transceiver; at least one processor coupled to the transceiver; and at least one memory coupled to the at least one processor and storing program code that when executed by the at least one processor causes the at least one processor to perform operations comprising: establishing a radio resource control, RRC, connection with a user equipment, UE; following establishment of the RRC connection, receiving an indication of a security capability of the UE from the UE; generating a list of security algorithms supported by the network node; transmitting the list of supported security algorithms to a core network node; receiving, from the core network node, a selected security algorithm; and sending the selected security algorithm to the UE.