Methods and devices for managing secure communications in a distributed network

Abstract

Methods and devices in a wireless communication network are configured to security protect Medium Access Control (MAC) control elements (CEs) by determining, at a central unit (CU) or a distributed unit (DU) of a radio access network (RAN) node, to activate such protection. A method for wireless communication performed by the CU or DU includes transmitting (1380 or 1420), to the DU or a user equipment (UE), respectively, a message associated with a secure algorithm for security protection of MAC CEs. The DU communicates (1328), with the UE, security protected MAC CEs and the CU communicates (1494) with the UE, through the DU, security protected data excluding the MAC CEs.

Description

PATENT APPLICATION Attorney Docket No.: 0683-125-WOMETHODS AND DEVICES FOR MANAGING SECURE COMMUNICATIONS IN A DISTRIBUTED NETWORKFIELD OF THE DISCLOSURE

[0001] This document generally describes methods and devices operating in wireless communication systems such as (but not limited to) the ones described in fifth generation (5G) standard documents, known as 3rdGeneration Partnership Project (3GPP) communication systems. The methods and devices are directed to managing secure communication for medium access control (MAC) control elements (CEs) in a distributed network.BACKGROUND

[0002] 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.

[0003] The 3GPP has standardized the 5G New Radio (NR) radio interface, including the protocol stack. A 5G NR wireless communication system architecture includes a 5G Core (5GC) network, a 5G Radio Access Network (5G-RAN), and a User Equipment (UE), among other components. The 5G NR delivers enhanced data rates, reduced latency, and increased capacity compared to prior cellular communication systems. The 5G NR protocol stack incorporates a physical layer (PHY), a MAC layer, a Radio Link Control (RLC) layer, a Packet Data Convergence Protocol (PDCP) layer, and a Radio Resource Control (RRC). 3GPP defines MAC Control Elements (CEs) for the MAC layer, each carrying specific control information. Each MAC CE is associated with a corresponding MAC CE subheader in a protocol data unit (PDU) transmission, which includes a logical channel identity (LCID) that identifies the respective MAC CE. The 5G NR currently transmits MAC CEs without security protection, which poses a security vulnerability as the potential for exploitation of the MAC CEs may increase as quantum computing and Artificial Intelligence (Al) technologies mature.PATENT APPLICATION Attorney Docket No.: 0683-125-WO

[0004] The International Telecommunication Union (ITU) has established a framework for the development of standards and radio interface technologies for sixth generation (6G) mobile systems. The 6G networks are anticipated to require robust computing resources and deeply integrated Al capabilities. Thus, the underlying infrastructure needs to facilitate agile development and deployment of distributed applications and network functions. Further, the 6G network needs to accommodate services for data and compute acceleration, with end-to-end performance guarantees.

[0005] The anticipated advancements in quantum computing and Al present a significant and evolving security challenge to the emerging 6G communication networks. Quantum computers, with their ability to rapidly solve complex mathematical problems, directly compromise existing communication protocols. Simultaneously, Al's adaptive learning capabilities will enable the development of sophisticated attack vectors that can bypass traditional detection methods. For example, Al-driven attacks could autonomously identify and exploit subtle network vulnerabilities in real time. The combination of quantum computing and Al creates a scenario where attacks become not only more powerful but also increasingly difficult to detect and mitigate due to their adaptive nature.

[0006] One vulnerability of the current 5G networks and the emerging 6G networks arises as the MAC CEs are transmitted without security protection. This leaves the network susceptible to spoofing. This vulnerability could lead to the disruption of 5G and 6G communication through the injection of counterfeit MAC CEs. For instance, a forged layer 1 / layer 2 triggered mobility (LTM) cell switch command could direct a UE to connect to an LTM candidate cell with insufficient signal strength, resulting in connection failure. Similarly, fraudulent Transmission Configuration Indicator (TCI) state activation or deactivation commands could force a UE to utilize a TCI state with poor signal quality, hindering communication.Furthermore, a fabricated Secondary Cell (SCell) deactivation command could abruptly terminate communication on the SCell. Note that the MAC CEs are responsible for controlling various aspects related to the LTM cell switch, TCI state activation and deactivation, and SCell connection.

[0007] In a disaggregated base station architecture, e.g., a base station that has a distributed unit (DU) and a central unit (CU), the DU employs a MAC protocol toPATENT APPLICATION Attorney Docket No.: 0683-125-WOcommunicate with UEs, exchanging MAC CEs that include essential information. However, mechanisms for enabling and managing secure transmission of these MAC CEs within the DU remain undefined.SUMMARY

[0008] In one embodiment, in addition to applying security protection to data communicated between a user equipment (UE) and a distributed radio access network (RAN) node (e.g., a distributed unit (DU) and / or a central unit (CU)), the distributed RAN node and the UE apply security protection to a medium access control (MAC) control element (CE). The data communicated between the UE and the distributed RAN node excludes the MAC CE. In one embodiment, the CU makes the decision to implement the security protection to the MAC CE and the CU activates the security protection at the DU and the UE. In another embodiment, the CU activates the security protection only at the DU and the UE is configured to activate the security protection based on information received from the DU. In yet another embodiment, the CU activates the security protection only at the DU and the DU activates the security protection at the UE.

[0009] In some embodiments, the DU makes the decision to activate the security protection for the MAC CE. For this situation, the DU informs the UE about activating the security protection. Alternatively, the DU informs the CU about the activation of the security protection and the CU requests the UE to implement the security protection. In another embodiment, the DU makes the decision to activate the security protection but requests CU approval before activating the security protection. In yet another embodiment, the DU makes the decision to activate the security protection and provides a configuration for the activation to the CU. The CU forwards to the UE the configuration for the activation of the security protection.

[0010] The security protection involves integrity protection, and / or ciphering protection. The CU or DU may decide to selectively apply the security protection of the MAC CE, based on the type of MAC CE. The DU and UE may communicate security protected and non-security protected MAC CEs. The security protected MAC CE, the non-security protected MAC CEs, and the communication data may be multiplexed in the same PDU.PATENT APPLICATION Attorney Docket No.: 0683-125-WOBRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1A is a block diagram of an example system having one or more RAN nodes and a UE that can implement the techniques of this disclosure related to securing MAC CEs and / or other communicated data.

[0012] FIG. 1 B is a block diagram of a RAN node that includes a Oil and one or more DUs.

[0013] FIG. 2A is a block diagram of an example protocol stack for UEs and RAN nodes as shown in FIG. 1 A.

[0014] FIG. 2B is a block diagram of an example protocol stack according to which the UE communicates with the CU and DU.

[0015] FIG. 3A is a signal diagram for a CU activated MAC CE security protection for MAC CE(s) transmitted between a distributed RAN node and a UE according to an embodiment.

[0016] FIG. 3B is another signal diagram fora CU activated MAC CE security protection for MAC CE(s) transmitted between a distributed RAN node and a UE according to an embodiment.

[0017] FIG. 3C is yet another signal diagram for a CU activated MAC CE security protection for MAC CE(s) transmitted between a distributed RAN node and a UE according to an embodiment.

[0018] FIG. 4A is a signal diagram for a DU activated MAC CE security protection for MAC CE(s) transmitted between a distributed RAN node and a UE according to an embodiment.

[0019] FIG. 4B is another signal diagram fora DU activated MAC CE security protection for MAC CE(s) transmitted between a distributed RAN node and a UE according to an embodiment.

[0020] FIG. 4C is yet another signal diagram for a DU activated MAC CE security protection for MAC CE(s) transmitted between a distributed RAN node and a UE according to an embodiment.

[0021] FIGs. 5A to 5E illustrate methods performed by a DU for applying security protection to transmitted MAC CE(s) according to embodiments.PATENT APPLICATION Attorney Docket No.: 0683-125-WO

[0022] FIGs. 6A to 6E illustrate methods performed by a CU for applying security protection to transmitted MAC CE(s) according to embodiments.

[0023] FIG. 7 A illustrates a method performed by the DU for security protecting the MAC CE based on at least one security parameter according to an embodiment.

[0024] FIG. 7B illustrates a method performed by the DU for security protecting the MAC CE based on at least one security key according to an embodiment.

[0025] FIG. 8A illustrates a method performed by the CU for security protecting data and security protecting the MAC CE based on different security parameters, according to an embodiment.

[0026] FIG. 8B illustrates a method performed by the CU for security protecting data and security protecting the MAC CE based on the same security parameter, according to an embodiment.

[0027] FIG. 8C illustrates a method performed by the CU for security protecting data and security protecting the MAC CE based on different security keys derived by the CU, according to an embodiment.

[0028] FIGs. 9A and 9B illustrate methods performed by a DU for security protecting a MAC CE transmitted to a UE based on a security algorithm according to an embodiment.

[0029] FIG. 10A illustrates a method performed by a CU for security protecting data and MAC CE(s) based on distinct security algorithms, according to an embodiment.

[0030] FIG. 10B illustrates a method performed by a CU for security protecting data and the MAC CE based on a same security algorithm, according to an embodiment.

[0031] FIG. 11 illustrates a method performed by a DU for integrity checking of a received MAC CE according to an embodiment.

[0032] FIG. 12 illustrates a method performed by a CU for integrity checking of a received MAC CE according to an embodiment.

[0033] FIG. 13 is a flowchart of a method performed by a DU for applying security protection to MAC CE exchanged with a UE according to an embodiment.

[0034] FIG. 14 is a flowchart of a method performed by a CU for applying security protection to MAC CE according to an embodiment.PATENT APPLICATION Attorney Docket No.: 0683-125-WO

[0035] FIG. 15 is a flowchart of a method performed by the UE for applying security protection to MAC CE according to an embodiment.

[0036] FIG. 16A illustrates using an integrity algorithm for integrity protection and integrity check of data according to an embodiment.

[0037] FIG. 16B illustrates using an integrity algorithm for integrity protection and integrity check of a MAC CE according to an embodiment.

[0038] FIG. 17A illustrates using a ciphering algorithm for encrypting and decrypting data according to an embodiment.

[0039] FIG. 17B illustrates using a ciphering algorithm for encrypting and decrypting MAC CEs according to an embodiment.

[0040] FIG. 18A shows a MAC protocol data unit (PDU) having one or more MAC subPDUs with a security protected MAC CE according to an embodiment.

[0041] FIG. 18B illustrates a MAC PDU having one or more MAC subPDUs with a security-protected MAC CE or a non-security protected MAC CE according to an embodiment.

[0042] FIG. 18C illustrates a MAC PDU with one or more MAC subPDUs having security protection according to an embodiment.

[0043] FIG. 18D illustrates a MAC PDU with one or more MAC subPDUs having security protection according to an embodiment.DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] Methods and devices described in this section embody techniques related to MAC CE security protection when communicated between the UE and the DU of a RAN node. The DU or the CU is configured to trigger the MAC CE security protection. Various scenarios are envisioned for triggering the MAC CE security protection, applying one or more secure algorithms for achieving the MAC CE security protection, and configuring the signaling between the UE, DU, and CU for managing the MAC CE security protection. These scenarios are discussed in the following embodiments with regard to the figures.

[0045] Prior to discussing the above noted scenarios, a wireless communication system 100 that supports security protection for MAC CEs is introduced, as illustrated in FIG. 1A. The wireless communication system 100 includes a UE 102, a first base station (BS) 104, a second BS 106 and a core network (CN) 110. The CNPATENT APPLICATION Attorney Docket No.: 0683-125-WO110 may be or include an evolved packet core (EPC) 111, a 5G core (5GC) 160 and / or a 6G core (6GC) 180. The first BS 104 may be an evolved NodeB (eNB) supporting an S1 interface for communicating with the EPC 111 , a next generation eNB (ng-eNB) supporting an NG interface for communicating with the 5GC 160, or a gNodeB (gNB) that supports an NR radio interface as well as an NG interface for communicating with the 5GC 160. The first BS 104 may also be an 6G BS supporting the NG interface, a new NG interface, ora 6G BS-to-CN (e.g., N6G) interface for communicating with the 5GC 160 or the 6GC 180. In one embodiment, the first BS 104 is a distributed RAN node, i.e., it includes a CU 172 and a DU 174. The configuration of such a distributed RAN node is discussed with regard to FIG.1B.

[0046] To directly exchange messages with each other during the scenarios discussed below, the BSs 104 and 106 may support an X2, Xn, newXn, or6G BS-to-BS (e.g., X6G) interface(s). Among other components, the EPC 111 may include a Serving Gateway (SGW) 112, a Mobility Management Entity (MME) 114, and a Packet Data Network Gateway (PGW) 116. The SGW 112 is generally configured to transfer user-plane packets related to audio calls, video calls, Internet traffic, etc., and the MME 114 is configured to manage authentication, registration, paging, and other related functions. The PGW 116 provides connectivity from the UE to one or more external packet data networks, e.g., an Internet network and / or an Internet Protocol (IP) Multimedia Subsystem (IMS) network.

[0047] The 5GC 160 includes a User Plane Function (UPF) 162, an Access and Mobility Management (AMF) 164, and / or a Session Management Function (SMF) 166. The UPF 162 is generally configured to transfer user-plane packets related to audio calls, video calls, Internet traffic, etc., the AMF 164 is configured to manage authentication, registration, paging, and other related functions, and the SMF 166 is configured to manage PDU sessions. The 6GC 180 includes a 6G UPF 182, a 6G AMF 184, and / or 6G SMF 186, similar to the UPF 162, the AMF 164, and the SMF 176, respectively, but with enhanced functions.

[0048] As illustrated in FIG. 1A, the first BS 104 supports a cell 124 (may support more cells, but only one is shown for simplicity), and the second BS 106 supports cells 126A, 126B, and 126C (may support fewer or more cells). The cells 124, 126A, 126B, and / or 126C may operate on the same carrier frequency or different carrierPATENT APPLICATION Attorney Docket No.: 0683-125-WOfrequencies. For example, the cells 126A, 126B and 126C operate on a downlink (DL) carrier frequencies f 1 , f2, and f3, respectively. The cell 124 may operate on the DL carrier frequency f1. In cases where the cells 124, 126A, 126B, and / or 126C operate in a time division duplex (TDD) mode, the cells 124, 126A, 126B, and / or 126C operate in an uplink (UL) carrier frequencies same as the DL carrier frequencies. In cases where the cells 124, 126A, 126B, and / or 126C operate in a frequency division duplex (FDD) mode, the cells 124, 126A, 126B, and / or 126C operate in UL carrier frequencies different from the DL carrier frequencies. The cells 124, 126A, 126B, and / or 126C may partially overlap to provide seamless service continuity. Thus, while the UE 102 may move among the cells 124, 126A, 126B and 126C, the UE 102 still communicates with the CN 110 via at least one of these cells. In some other scenarios, the cells 126B and / or 126C may belong to one or more other BSs (e.g. , the BS 104 and / or one or more additional BSs not shown in FIG. 1A).

[0049] The wireless communication network 100 may include any suitable number of BSs supporting 6G cells, NR cells, and / or EUTRA cells. More particularly, the EPC 111 may be connected to any suitable number of BSs supporting EUTRA cells, while the 5GC 160 and / or the 6GC 180 may be connected to any suitable number of BSs supporting 6G cells and / or NR cells. Although the examples below refer to specific CN types (EPC, 5GC, 6GC) and radio access technologies (RAT) types (6G, 5G NR and EUTRA), in general, the techniques of this disclosure also may apply to other suitable radio access and / or core network technologies such as seventh generation (7G) radio access and / or 7G core network.

[0050] With continued reference to FIG. 1A, the first BS 104 is equipped with processing hardware 130 that includes one or more general-purpose processors (e.g., CPUs) and a non-transitory computer-readable memory (CRM) storing instructions that the one or more general-purpose processors execute. Additionally or alternatively, the processing hardware 130 may include special-purpose processing units. According to an embodiment illustrated in FIG. 1A, the processing hardware 130 includes a processor 132 to process data that the first BS 104 transmits in the DL direction, or data that the first BS 104 receives in the UL direction. The processing hardware 130 also includes a transceiver 134 configured to transmit data in the DL direction and to receive data in the UL direction. ThePATENT APPLICATION Attorney Docket No.: 0683-125-WOprocessing hardware 136 also includes a MAC CE security manager 136 configured to manage security protection for communicating one or more MAC CEs with UE(s). The processing hardware 130 also includes a data security manager 138 configured to manage security protection for data communication (e.g., data that excludes MAC CEs; the data may include both user and control data). The CRM (not shown) stores executable codes for the processor 132 to perform methods according to embodiments described in this section. The second BS 106 includes generally similar components. In particular, components 140, 142, 144, 146, and 148 of the second BS 106 may be similar to the components 130, 132, 134, 136, and 138, respectively.

[0051] The UE 102 is equipped with processing hardware 150 that may include one or more general-purpose processors such as CPUs and non-transitory CRM storing machine-readable instructions executable on the one or more general-purpose processors, and / or special-purpose processing units. As schematically illustrated in FIG. 1A, the processing hardware 150 includes a processor 152 to prepare data that the UE 102 transmits in the UL direction, or to process data that the UE 102 receives in the DL direction. The processing hardware 150 also includes a transceiver 154 configured to transmit data in the UL direction and to receive data in the DL direction. The processing hardware 150 further includes a MAC CE security manager 156 configured to manage security protection for communicating one or more MAC CEs with the DU or CU. The processing hardware 150 also includes a data security manager 158 configured to manage security protection for data communication.

[0052] FIG. 1 B depicts an example of a distributed RAN node, e.g., the first BS 104. Note that the second BS 106 may have the same distributed configuration. The BS 104 in this embodiment may include a CU 172 and one or more DUs 174. The CU 172 is equipped with processing hardware that may include one or more general-purpose processors such as CPUs and non-transitory computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and / or special-purpose processing units. In one example, the CU 172 is equipped with the processing hardware 130 (FIG. 1A). In another example, the CU 172 is equipped with the processing hardware 140 (FIG. 1A). The processing hardware 130, in an example embodiment, includes a data securityPATENT APPLICATION Attorney Docket No.: 0683-125-WOmanager that may be similar to data security manager 138 (FIG. 1 A) configured to manage or control a security configuration and / or security activation for data communication. The DU 174 is also equipped with processing hardware that may include one or more general-purpose processors such as CPUs and non-transitory computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and / or special-purpose processing units. In some examples, the processing hardware in an example embodiment includes a MAC controller configured to manage or control one or more MAC operations or procedures (e.g., a random access procedure) and / or a radio link control (RLC) controller configured to manage or control one or more RLC operations or procedures. The processing hardware may further include a physical layer controller configured to manage or control one or more physical layer operations or procedures. In an example embodiment, the CU 172 and the DU 174 communicate with each other via a fiber, an Ethernet cable, ora peripheral component interconnect express (PCIe). In another example embodiment, the CU 172 and the DU 174 communicate with each other via a memory (e.g., shared memory or RAM).

[0053] FIG. 2A illustrates, in a simplified manner, an example protocol stack 200 according to which the UE 102 may communicate with a 6gNB (i.e., a 6G RAN node) and / or a gNB (e.g., one or more of the BSs 104, 106).

[0054] In the example stack 200, an NR physical layer (PHY) 202B provides transport channels to a NR MAC sublayer 204B, which in turn provides logical channels to a NR RLC sublayer 206B. The NR RLC sublayer 206B in turn provides data transfer services to an NR PDCP sublayer 208B. The NR PDCP sublayer 208B in turn may provide data transfer services to a Service Data Adaptation Protocol (SDAP) 210B sublayer and / or an RRC sublayer 212B. Similarly, a 6G PHY 202A provides transport channels to a 6G MAC sublayer 204A, which in turn provides logical channels to the 6G RLC sublayer 206A. The 6G RLC sublayer 206A in turn provides RLC channels to a 6G PDCP sublayer 208A. The 6G PDCP sublayer 208A in turn may provide data transfer services to a 6G SDAP sublayer 210A or a 6G RRC sublayer 212A. In some embodiments, the 6G SDAP sublayer 210A may be omitted. In such cases, the PDCP sublayer 208A may support functionalities of the SDAP sublayer 210A. The UE 102, in some embodiments, supports both the 6G and the NR stack as shown in FIG. 2A. This means that the UE is capable to supportPATENT APPLICATION Attorney Docket No.: 0683-125-WOhandover between 6G and NR BSs and / or to support dual communication (DC) over 6G and NR interfaces.

[0055] The 6G PDCP sublayer 208A and the NR PDCP sublayer 208B receive packets (e.g., from an Internet Protocol (IP) layer, layered directly or indirectly over the PDCP layer 208A or 208B) that may be referred to as service data units (SDUs), and output packets (e.g., to the RLC layer 206A or 206B) that may be referred to as protocol data units (PDlls). Except where the difference between SDUs and PDUs is relevant, this document, for simplicity, refers to both SDUs and PDUs as “packets.”

[0056] In one embodiment, on a control plane, the 6G PDCP sublayer 208A and the NR PDCP sublayer 208B may provide services to the RRC sublayer 212A and the RRC sublayer 212B to exchange RRC messages or non-access-stratum (NAS) messages, respectively. On a user plane, the 6G PDCP sublayer 208A and the NR PDCP sublayer 208B may provide services to the SDAP 210 and the SDAP 210B to support a data exchange, respectively. In some embodiments, the 6G PDCP sublayer 208A and the NR PDCP sublayer 208B may provide services to upper layer(s) (e.g., Internet Protocol (IP) layer or Ethernet layer) to support a data exchange. The services may include data transfer services, integrity protection, ciphering, header compression, and / or data compression. Data exchanged on the 6G PDCP sublayer 208A and NR PDCP sublayer 208B may be SDAP PDUs, IP packets, or Ethernet packets.

[0057] FIG. 2B illustrates, in a simplified manner, an example protocol stack 250, which the UE 102 may communicate with a DU (e.g., DU 174) and a CU (e.g., CU 172). The protocol stack 200 is functionally split as shown by the radio protocol stack 250 in FIG. 2B. The CU at any of the BSs 104A or 106A may hold all the control and upper layer functionalities (e.g., RRC 212, SDAP 210, PDCP 208), while the lower layer operations (e.g., RLC 206, MAC 204, and PHY 202) are delegated to the DU. The PDCP 208 provides services to RRC 212, and the PDCP 208 provides services to SDAP 210 and / or upper layer(s), as described for FIG. 2A.

[0058] Next, several example scenarios, in which the UE and a distributed RAN node (e.g., BS 104 including CU 172 and DU 174) operate in the system of FIG. 1A, are described and include applying security protection to communication data and MAC CEs. The events in FIGs. 3A-3B, 4A-5B, and 9A-14C that are similar are labeled with similar reference numbers {e.g., event 394 of FIGs. 3A and 3B arePATENT APPLICATION Attorney Docket No.: 0683-125-WOsimilar to event 494 of FIGs. 4A and 4B, event 594 of FIGs. 5A and 5B, and event 1094 of FIGs. 10A and 10B; event 316 of FIG. 3A is similar to event 616 of FIG. 6A, event 416 of FIG. 6B, and event 616 of FIG. 6C; etc.), with differences discussed below where appropriate. With the exception of the differences shown in the figures and discussed below, any of the alternative embodiments discussed with respect to a particular event (e.g., for messaging and processing) may apply to events labeled with similar reference numbers in other figures. Also, if a step, block, or event is marked with a dash line, it means that the step, block, or event is optional. Further, two or more steps, blocks, or events are numbered with consecutive numbers, there is no implication that a specific order of these steps, blocks, or events is implied.

[0059] FIGs. 3Ato 15 illustrate messages exchanged between the UE 102 and one or both units (i.e., CU 172 and DU 174) of the distributed RAN node (e.g., the first BS 104 or the second BS 106) for a number of scenarios relating to the management of security protection of the MAC CE. In particular, FIGs. 3A to 3B depict MAC CE security protection management initiated by the CU, FIGs. 4A to 4B depict MAC CE security protection management initiated by the DU, FIGs. 5A to 5E depict messages exchanged by the DU with the UE and CU for MAC CE security protection, FIGs. 6A to 6E depict messages exchanged by the CU with the UE and DU for MAC CE security protection, FIGs. 7A and 7B depict MAC CE security related details in methods performed by the DU, FIGs. 8A to 8C depict MAC CE security related details in methods performed by the CU, FIGs. 9A and 9B depict the use of security algorithms by the DU, FIGs. 10A and 10B depict the use of security algorithms by the CU, FIG. 11 depicts the response of the DU if a security check fails, FIG. 12 depicts the response of the CU if a security check fails, FIG. 13 depicts how the DU performs the security protection of the MAC CE, FIG. 14 depicts how the CU contributes to the security protection of the MAC CE, FIG. 15 depicts how the UE performs the security protection of the MAC CE, FIGs 16A and 16B detail the inputs used by an integrity algorithms; FIGs. 17A and 17B detail the inputs used by ciphering and deciphering algorithms, and FIGs. 18A to 18D illustrate the multiplexing of data and security protected MAC CEs.

[0060] Referring first to FIG. 3A, in a scenario 300A, the BS 104 (also called “distributed RAN node” or “RAN node” in this document) includes a CU 172 and a DU 174 and the DU 174 operates the cell 124. The UE 102 initially performs 390 aPATENT APPLICATION Attorney Docket No.: 0683-125-WOconnection establishment procedure with the BS 104. As a result of the connection procedure, the UE 102 and the BS 104 establish a connection with each other. In some embodiments, the connection includes an SRB. For example, the SRB is a SRB1. In some embodiments, the UE 102 may transition to a connected state after (e.g., in response to) the connection establishment procedure.

[0061] In some embodiments, during or after the procedure 390, the UE 102 receives 302 one or more DL MAC PDUsfrom the DU 174 and / or transmits 304 one or more UL MAC PDUs to the DU 174. In some embodiments, some of the DL MAC PDUs may include at least one non-security-protected DL MAC CE. In some embodiments, some of the UL MAC PDUs may include at least one non-security-protected UL MAC CE. In some embodiments, some of the DL MAC PDUs may include at least one non-security-protected DL data packet(s). In some embodiments, the DL data packet(s) includes at least one user-plane (UP) data packet and / or at least one control-plane (CP) message (e.g., DL RRC message or DL NAS message). In one embodiment, the DL data packet(s) exclude UP data packets. In some embodiments, some of the UL MAC PDUs may include at least one non-security-protected UL data packet(s). In some embodiments, the UL data packet(s) includes at least one UP data packet and / or at least one CP message (e.g., UL RRC message or UL NAS message). In other embodiments, the UL data packet(s) exclude UP data packets.

[0062] Part of the connection establishment procedure 390, the UE 102 transmits a connection request message to the DU 174 to initiate the connection establishment procedure. The steps described in this document for the connection establishment procedure 390 are not illustrated in the figures. The DU 174 in turn transmits the connection request message to the CU 172. After (e.g., in response to) receiving the connection request message, the CU 172 may transmit a UE context setup message to the DU 174. In response, the DU 174 transmits, to the CU 172, a UE context setup response message including a DU configuration (e.g., a cell group configuration) for the UE 102. After (e.g., in response to) receiving the connection request message or performing the UE context setup procedure, the CU 172 transmits a connection establishment message to the UE 102 to set up the connection. The CU 172 may include the DU configuration in the connection establishment message. In response to the connection establishment message, thePATENT APPLICATION Attorney Docket No.: 0683-125-WOUE 102 may transmit a connection complete message to the CU 172, via the DU 174, to complete the connection establishment procedure. In some embodiments, the connection establishment procedure is an RRC connection establishment procedure. In some embodiments, the connection request message, the connection establishment message, and the connection complete message are an RRC setup request message, an RRC setup message, and an RRC setup complete message, respectively.

[0063] After establishing 390 the connection (e.g., transmitting the connection establishment message or receiving the connection complete message) with the UE 102, the CU 172 determines to activate or activates 306 security protection for communicating data (e.g., CP data and / or UP data; the communication data considered in this embodiment excludes MAC CEs) with the UE 102. In response to determining to activate or activating 306 security protection, the CU 172 applies security protection to a security mode command message to generate a respective security-protected security mode command. The CU 172 then transmits 308 a first CU-to-DU message including the security-protected security mode command to the DU 174. The DU 174 retrieves the security-protected security mode command from the first CU-to-DU message and transmits 310 the security-protected security mode command to the UE 102. In response to receiving 310 the security-protected security mode command, the UE 102 activates 312 security protection for communicating data packets (e.g., CP data and / or UP data) with the CU 172. Note that the data packets exclude MAC CEs. Also note that the security protection for the data packets (or communication data) is applied at a layer level above the MAC layer 204, for example, at PDCP layer 208 (see FIG. 2B).

[0064] After activating 312 security protection and in response to the security-protected security mode command, the UE 102 applies security protection to a security mode complete message to obtain a security-protected security mode complete message. The UE 102 then transmits 314 the security-protected security mode complete message to the DU 174. The DU 174 in turn transmits 316 a first DU-to-CU message including the security-protected security mode complete message to the CU 172.

[0065] In some embodiments, the first CU-to-DU message is a DL RRC Message Transfer message. In other embodiments, the first CU-to-DU message is a UEPATENT APPLICATION Attorney Docket No.: 0683-125-WOContext Modification Request message. In such cases, the DU 174 may transmit a UE Context Modification Response message to the CU 172 in response to the UE Context Modification Request message.

[0066] In some embodiments, the CU 172 generates, for transmission 308, a first DL PDU (e.g., a PDCP PDU) including the security-protected security mode command and includes the first DL PDU in the first CU-to-DU message. In some embodiments, the DU 174 includes, for transmission 310, the first DL PDU in a DL MAC PDU and transmits the DL MAC PDU to the UE 102. The UE 102 retrieves the first DL PDU from the DL MAC PDU and retrieves the security-protected security mode command from the first DL PDU. In some embodiments, the UE 102 includes, for transmission 314, the security-protected security mode complete message in a first UL PDU, includes the first UL PDU in a UL MAC PDU, and transmits the first UL MAC PDU to the DU 174. The DU 174 retrieves, for transmission 316, the first UL PDU from the UL MAC PDU and includes the first UL PDU in the first DU-to-CU message.

[0067] In some embodiments, after activating 306 security protection, the CU 172 applies a security check to the received security mode complete message. After activating 312 the security protection, the UE 102 communicates 394 security-protected data packets with the CU 172 via the DU 174. In this embodiment, the data packets exclude the MAC CEs. Similarly, after activating 306 the security protection and / or receiving the security mode complete message, the CU 172 communicates 394 security-protected data packets with the UE 102 via the DU 174. In some embodiments, the data packets include CP data packets (e.g., UL RRC message, DL RRC messages, UL NAS messages, and / or DL NAS messages) and / or UP data packets (e.g., Internet Protocol packets and / or Ethernet protocol packets).

[0068] In some embodiments, the security protection includes integrity protection and check and / or encryption and decryption. Here, “encryption” and “decryption” are interchangeably used with “ciphering” and “deciphering,” respectively. In some embodiments, the security mode command configures an integrity algorithm (i.e. , a first integrity algorithm) for integrity protection and verification. In some embodiments, the UE 102 obtains a first integrity key for integrity protection and check. In some embodiments, the UE 102 derives the first integrity key based on a first base key, an identity or identifier (ID) of the integrity algorithm, a key derivationPATENT APPLICATION Attorney Docket No.: 0683-125-WOfunction, and / or one or more additional parameters. In some embodiments, the UE 102 obtains the one or more additional parameters from a universal subscriber identity module (IISIM). In other embodiments, the UE 102 receives a DL NAS message configuring, indicating, or including the one or more additional parameters, from a CN node (e.g., AMF 164 or6G AMF 184) via a distributed BS (e.g., the BS 104 or 106).

[0069] In yet other embodiments, the UE 102 derives the one or more additional parameters based on at least one parameter in a DL NAS message received from the CN node via the BS. In yet other embodiments, the UE 102 derives the one or more additional parameters based on at least one parameter obtained from the USIM. In yet other embodiments, the CU 172 generates the one or more additional parameters and the UE 102 receives the one or more additional parameters from the CU 172 via the DU 174. In some embodiments, the first base key is a first key for the BS 104 (KBS). In some embodiments, the first KBS is a K9NB or a KS9NB. In some embodiments, the UE 102 derives the first base key from a first key for CN (KCN). In some embodiments, the first KCN is a KAMF or a K69AMF.

[0070] In some embodiments, the CU 172 obtains a first integrity key (i.e., same as the first integrity key obtained by the UE 102). In some embodiments, the CU 172 derives the first integrity key (i.e., same as the first integrity key derived by the UE 102) using a first base key (i.e., same as the first base key used by the UE 102 to derive the first integrity key of the UE 102), a key derivation function (same as the key derivation function used by the UE 102), the identifier (ID) of the integrity algorithm, and / or one or more additional parameters (i.e., same as the one or more additional parameters used by the UE 102 to derive the first integrity key of the UE 102). In some embodiments, the CU 172 receives the one or more additional parameters in a CN-to-CU message (also called a CN-to-BS message) from a CN node (e.g., an AMF such as AMF 164 or 6G AMF 184). In other embodiments, the CU 172 generates the one or more additional parameters. In some embodiments, the one or more additional parameters include security capabilities of the UE 102, indicating support of one or more integrity algorithms. The one or more integrity algorithms include the first integrity algorithm and / or the second integrity algorithm described above or below. In some implementations, the CU 172 receives the firstPATENT APPLICATION Attorney Docket No.: 0683-125-WObase key from the GN node. The CN node generates the first base key from the first KCN.

[0071] In some embodiments, the CU 172 applies integrity protection to the security mode command after or in response to event 306. In some embodiments, the CU 172 generates a first message authentication code for integrity (MAC-I) for protecting security of the security mode command. The CU 172 may generate the first MAC-I using the first integrity key, the integrity algorithm, and / or additional parameter(s), which are discussed later with regard to FIG. 16A. For example, the additional parameter(s) include(s) COUNT, BEARER, and / or DIRECTION as shown in FIG. 16A and as discussed above. As an example, the COUNT may be associated with the security mode command. For example, the COUNT includes a hyper frame number (HFN) and a PDCP sequence number. The CU 172 assigns the PDCP sequence number for the security mode command and includes the PDCP sequence number in the first DL PDU. The BEARER may be a bearer identity (i.e., a value) identifying a bearer used by the CU 172 to transmit the security mode command. For example, the bearer is an SRB1 and the BEARER is 1. The DIRECTION may be associated with downlink. For example, the DIRECTION (e g., a bit) is set to 1 for downlink. The CU 172 generates the first DL PDU including the security mode command and the first MAC-I and transmits 308 the first DL PDU to the DU 174. The first DL PDU may be a PDCP PDU. Upon receiving 310 the first DL PDU, the UE 102 retrieves the first MAC-I from the first DL PDU. The UE 102 verifies whether the first MAC-I is valid, using the security mode command, the first integrity key, the integrity algorithm, and / or additional parameter(s). For example, the additional parameter(s) include(s) COUNT, BEARER, and / or DIRECTION as shown in FIG. 16A. Generally, the additional parameter(s) used by the UE 102 are the same as the additional parameter(s) used by the CU 172. If the UE 102 determines that the first MAC-I is valid, the UE 102 activates 312 security protection (e.g., integrity protection and check and / or encryption and decryption) for communicating data (e.g., CP data and / or UP data) with the BS 104.

[0072] The UE 102 then applies the security protection to the security mode complete message and transmits 314 the security-protected security mode complete message to the RAN node 104, as described above or below. Otherwise, if the UE 102 verifies that the first MAC-I is invalid, the UE 102 skips event 312 and transmitsPATENT APPLICATION Attorney Docket No.: 0683-125-WOa security mode failure message to the BS 104. That is, the UE 102 transmits the security mode failure message to the BS 104 without applying security protection to the security mode failure message. In some embodiments, the UE 102 generates a null MAC-I (e.g., a MAC-I that only includes “0”) and transmits a UL PDU, including the security mode failure message and the null MAC-I, to the CU 172 via the DU 174. Thus, the CU 172 correctly retrieves the security mode failure message from the UL PDU. If the UE 102 does not include the null MAC-I in the UL PDU and the CU 172 determines that the UL PDU includes a MAC-I, the CU 172 would determine a wrong end octet for the security mode failure message in the UL PDU. As a result, the CU 172 would not be able to retrieve the security mode failure message from the UL PDU.

[0073] In some embodiments, the security mode command message configures an encryption algorithm (i.e. , a first encryption algorithm) for encryption and decryption. The security mode command message may configure the encryption algorithm in addition to the integrity algorithm discussed above. In some embodiments, the UE 102 obtains a first encryption key, for encryption and decryption, in response to the security mode command message. In some embodiments, if the UE 102 verifies that the first MAC-I is valid, the UE 102 obtains the first encryption key. Otherwise, the UE 102 refrains from obtaining the first encryption key. In some embodiments, the UE 102 obtains (i.e., derives) the first encryption key based on a second base key, an ID of the encryption algorithm, a key derivation function, and / or one or more additional parameters. In some embodiments, the UE 102 obtains the one or more additional parameters from a USIM. In other embodiments, the UE 102 receives a DL NAS message configuring, indicating, or including the one or more additional parameters from a CN function (e.g., the AMF 164 or the G6 AMF 184) via a BS (e.g., the BS 104 or 106). In yet other embodiments, the UE 102 derives the one or more additional parameters based on at least one parameter in a DL NAS message received from the CN function via the BS. In yet other embodiments, the UE 102 derives the one or more additional parameters based on at least one parameter obtained from the USIM. In yet other implementations, the CU 172 generates the one or more additional parameters and the UE 102 receives the one or more additional parameters from the CU 172 via the DU 174. In some embodiments, the second base key is a second keyPATENT APPLICATION Attorney Docket No.: 0683-125-WOfor the BS 104 (KBS). In some embodiments, the second KBS is a K9NB or a KegNB. In one embodiment, the second base key is the same as the first base key.Alternatively, the second base key is different from the first base key. In some embodiments, the UE 102 derives the second base key from a second key forCN (KCN). In some embodiments, the second KCN is a KAMF or a K69AMF. In one embodiment, the second key for CN is the same as the first key for CN. Alternatively, the second key for CN is different from the first key for CN. In some embodiments, the one or more additional parameters are the same as the one or more additional parameters used for deriving the first integrity key.

[0074] In some embodiments, the CU 172 obtains a first encryption key (i.e., same as the first encryption key obtained by the UE 102) after or in response to event 306 or 308. In some embodiments, the CU 172 derives the first encryption key (i.e., same as the first encryption key derived by the UE 102) based on a second base key (i.e., same as the second base key used by the UE 102 to derive the first encryption key of the UE 102), the ID of the encryption algorithm, and / or one or more additional parameters (i.e., same as the one or more additional parameters used by the UE 102 to derive the first encryption key of the UE 102). In some embodiments, the CU 172 receives the second base key from the CN node. The CN node generates the second base key from the second KCN. In some embodiments, the CU 172 receives the one or more additional parameters in a CN-to-CU message from the CN node. In other embodiments, the BS 104 generates the one or more additional parameters. In some embodiments, the one or more additional parameters are the same as the one or more additional parameters used for deriving the first integrity key. In some embodiments, the one or more additional parameters include security capabilities of the UE 102, indicating that the UE supports of one or more encryption algorithms. The one or more encryption algorithms include the first encryption algorithm and / or the second encryption algorithm described above or below.

[0075] To transmit the security mode complete message, the UE 102 applies security protection (e.g., integrity protection and / or encryption) to the security mode complete message to generate a respective security-protected security mode complete message. The UE 102 generates, for the transmission 314, the first UL PDU including the security-protected security mode complete message, generates aPATENT APPLICATION Attorney Docket No.: 0683-125-WOUL MAC PDU including the first UL PDU, and transmits the UL MAC PDU to the DU 174. The first UL PDU may be a PDCP PDU. The DU 174 retrieves, from the communication 316, the first UL PDU from the UL MAC PDU and transmits the first UL PDU to the CU 172. The CU 172 retrieves the security-protected security mode complete message from the first UL PDU and verifies whether the security-protected security mode complete message is valid.

[0076] When or after activating 312 the integrity protection at the UE 102, the UE 102 generates a second MAC-I to protect the integrity of the security mode complete message. The UE 102 may generate the second MAC-I using a first integrity key, the integrity algorithm, and / or additional parameter(s), as described for FIG. 16A. For example, the additional parameter(s) include(s) COUNT, BEARER, and / or DIRECTION. As an example, the COUNT may be associated with the security mode complete message. For example, the COUNT includes a HFN and a PDCP sequence number. The UE 102 assigns the PDCP sequence number for the security mode complete message and includes the PDCP sequence number in the first UL PDU. The BEARER may be a bearer identity (i.e. , a value) identifying a bearer used by the UE 102 to transmit the security mode complete message. For example, the bearer is an SRB1 and the BEARER is 1. The DIRECTION may be associated with the uplink. For example, the DIRECTION (e.g., a bit) is set to 0 for the uplink. In some embodiments, when encryption is not enabled (e.g., null encryption is enabled by the security mode command message), the security-protected security mode complete message includes the security mode complete message and the second MAC-I.

[0077] When the CU 172 receives the first UL PDU, the CU 172 retrieves the security mode complete message and the second MAC-I from the first UL PDU and verifies the second MAC-I. The CU 172 may verify whether the second MAC-I is valid using the first integrity key (e.g., same as the first integrity key used by the UE 102), the integrity algorithm, and / or additional parameter(s) (e.g., same as the first integrity key used by the UE 102) as described with regard to FIG. 16A. In other embodiments, when encryption is enabled (e.g., by the security mode command message as described above), the UE 102 encrypts the security mode complete message and the second MAC-I to obtain an encrypted security mode complete message and an encrypted MAC-I, respectively. The UE 102 may encrypt thePATENT APPLICATION Attorney Docket No.: 0683-125-WOsecurity mode complete message and the second MAC-1 using the first encryption key, the encryption algorithm, and / or additional parameter(s) as described with regard to FIG. 17A. For example, the additional parameter(s) include(s) COUNT, BEARER, and / or DIRECTION as described above.

[0078] In such embodiments, the security-protected security mode complete message includes the encrypted security mode complete message and the encrypted MAC-I. When receiving 316 the first UL PDU, the CU 172 retrieves the encrypted security mode complete message and the encrypted MAC-I from the first UL PDU. The CU 172 decrypts the encrypted security mode complete message and the encrypted MAC-I to obtain a (decrypted) security mode complete message and a (decrypted) MAC-I. The CU 172 may decrypt the encrypted security mode complete message and the encrypted MAC-I using the first encryption key, the encryption algorithm, and / or additional parameter(s) as described with regard to FIG. 17A. For example, the additional parameter(s) include(s) COUNT, BEARER, and / or DIRECTION and are the same as the additional parameter(s) used by the UE 102. The CU 172 then verifies whether the (decrypted) MAC-I is valid as described above for verifying the second MAC-I. To simplify the following description, the second MAC-I is used to represent the (decrypted) MAC-I.

[0079] If or after the second MAC-I is determined to be valid, the CU 172 transmits 394 security-protected DL data packets (excluding MAC CEs) to the UE 102 via the DU 174. In some embodiments, when integrity protection is activated as described above, the CU 172 generates a respective MAC-I for protecting the integrity of each of the DL data packets using the first integrity key, the integrity algorithm, and / or additional parameter(s), similar to the security mode command message. For example, the additional parameter(s) include(s) COUNT, BEARER, and / or DIRECTION. The CU 172 uses (e.g., determines, generates, or assigns) a COUNT for each of the DL data packets. The CU 172 sets a BEARER to a bearer identity (i.e., a value) for identifying a bearer used by the CU 172 to transmit a respective DL data packet. The CU 172 may set the DIRECTION to a value (e.g., 1) for DL. In such embodiments, each of the security-protected DL data packets includes a respective integrity-protected DL data packet (i.e., a DL data packet and a respective MAC-I). In such cases, the UE 102 receives each of the integrity-PATENT APPLICATION Attorney Docket No.: 0683-125-WOprotected DL data packets and verifies the respective MAC-1 as described for the security mode command message.

[0080] In other embodiments, when encryption is activated as described above, the CU 172 encrypts each of the DL data packets to generate a respective encrypted DL data packet, using the first encryption key, the encryption algorithm, and / or additional parameter(s), similar to encrypting the second mode complete message as described for the UE 102. For example, the additional parameter(s) include(s) COUNT, BEARER, and / or DIRECTION as described above. In such cases, each of the security-protected DL data packets includes a respective encrypted DL data packet. When the UE 102 receives each of the encrypted DL data packets, the UE 102 decrypts each encrypted DL data packet using the first encryption key, the encryption algorithm, and / or additional parameter(s), similar to decrypting the security mode complete message as described for the CU 172. For example, the additional parameter(s) include(s) COUNT, BEARER, and / or DIRECTION and are the same as the additional parameter(s) used by the CU 172.

[0081] In yet other embodiments, when both integrity protection and encryption are enabled, the CU 172 generates a MAC-I for protecting integrity of each of the DL data packets, as described for the security mode command message. The CU 172 then encrypts each DL data packet along with the respective MAC-I to generate an encrypted DL packet and an encrypted MAC-I, using the first encryption key, the encryption algorithm, and / or additional parameter(s), similar to encrypting the security mode complete message as described for the UE 102. For example, the additional parameter(s) include(s) COUNT, BEARER, and / or DIRECTION as described above. In such cases, each of the security-protected DL data packets includes a respective encrypted DL data packet and a respective encrypted DL MAC-I. The UE 102 decrypts each DL data packet and the respective MAC-I, using the first encryption key, the encryption algorithm, and / or additional parameter(s), similar to decrypting the security mode complete message as described with regard to the BS 104. Generally, the additional parameter(s) used by the UE 102 are the same as the additional parameter(s) used by the CU 172.

[0082] In some embodiments, the CU 172 includes each of the security-protected DL data packets in a respective PDCP PDU and transmits 394 the PDCP PDU to thePATENT APPLICATION Attorney Docket No.: 0683-125-WOUE 102 via the DU 174. The UE 102 retrieves each security-protected DL data packet from the respective PDCP PDU.

[0083] After transmitting 314 the security mode complete message, the UE 102 transmits 394 security-protected UL data packets to the CU 172 via the DU 174. In some embodiments, when integrity protection is activated as described above, the UE 102 generates a respective MAC-I for protecting integrity of each of the UL data packets as described for the security mode complete message using the first integrity key, the integrity algorithm, and / or additional parameter(s), similar to the security mode complete message. For example, the additional parameters) include(s) COUNT, BEARER, and / or DIRECTION. The UE 102 uses (e.g., determines, generates, or assigns) a COUNT for each of the UL data packets. The UE 102 sets a BEARER to a bearer identity (i.e., a value) for identifying a bearer used by the UE 102 to transmit a respective UL data packet. The UE 102 may set the DIRECTION to a value (e.g., 0) for the UL. In such embodiments, each security-protected UL data packet includes a respective integrity-protected UL data packet (i.e., a respective UL data packet and a respective MAC-ls). In such cases, the CU 172 receives and applies integrity check on each of the integrity-protected UL data packets and verifies a respective MAC-I as described for the security mode complete message.

[0084] In other embodiments, when encryption is activated as described above, the UE 102 encrypts each of the UL data packets to generate a respective encrypted UL data packet, using the first encryption key, the encryption algorithm, and / or additional parameter(s), similar to encrypting the second mode complete message. For example, the additional parameter(s) include(s) COUNT, BEARER, and / or DIRECTION. The UE 102 uses (e.g., determines, generates or assigns) a COUNT for each of the UL data packets. The UE 102 sets a BEARER to a bearer identity (i.e., a value) identifying a bearer used by the UE 102 to transmit a respective UL data packet. The UE 102 may set the DIRECTION to a value (e.g., 0) for UL. In such cases, each of the security-protected UL packets includes a respective encrypted UL data packet. When the CU 172 receives each of the encrypted UL data packets, the CU 172 decrypts each encrypted UL data packet using the first encryption key, the encryption algorithm, and / or additional parameter(s), similar to decrypting the security mode complete message. For example, the additional parameter(s)PATENT APPLICATION Attorney Docket No.: 0683-125-WOinclude(s) COUNT, BEARER, and / or DIRECTION. Generally, the additional parameter(s) used by the CU 172 are the same as the additional parameter(s) used by the UE 102.

[0085] In yet other embodiments, when both integrity protection and encryption are enabled, the UE 102 generates a MAC-I for protecting the integrity of each of the UL data packets using the first integrity key, the integrity algorithm, and / or additional parameter(s) as described for the security mode command message above. The UE 102 then encrypts each UL data packet along with the respective MAC-I to generate an encrypted UL packet and an encrypted MAC-I, using the first encryption key, the encryption algorithm, and / or additional parameter(s), similar to encrypting the security mode complete message. For example, the additional parameter(s) include(s) COUNT, BEARER, and / or DIRECTION as described above. In such cases, each of the security-protected UL packets includes a respective encrypted UL data packet and a respective encrypted MAC-I. The CU 172 decrypts each UL data packet and each respective MAC-I, using the first encryption key, the encryption algorithm, and / or additional parameter(s), similar to decrypting the security mode complete message. Generally, the additional parameter(s) used by the CU 172 are the same as the additional parameter(s) used by the UE 102.

[0086] In some embodiments, the UE 102 includes each of the security-protected UL data packets in a respective PDCP PDU and transmits the 394 the PDCP PDU to the BS 104. The CU 172 receives the PDCP PDUs from the UE 102 via the DU 174 and retrieves each security-protected UL data packet from the respective PDCP PDU.

[0087] In some embodiments, the DL data packets include at least one DL message (e.g., RRC message(s) or CP message(s)). In some embodiments, the at least one DL message includes a UE capability enquiry message, at least one reconfiguration message (e.g., RRCReconfiguration message(s)), and / or at least one DL information transfer message. In some embodiments, the UL data packets include at least one UL message (e.g., RRC message(s) or CP message(s)). In some embodiments, the at least one UL message includes a UE capability information message, at least one reconfiguration complete message (e.g., RRCReconfigurationComplete message), at least one UL information transfer message, and / or at least one measurement report message. Each of the at least onePATENT APPLICATION Attorney Docket No.: 0683-125-WOreconfiguration complete message responds to a respective one of the at least one reconfiguration message. In some embodiments, one of the at least one reconfiguration message configures one or more radio bearer(s). The radio bearer(s) may include an SRB (e.g., SRB2) and / or a DRB. In some embodiments, one or some of the at least one reconfiguration message includes one or more measurement configurations. When the UE 102 and DU 174 communicate DL data packets and / or UL data packets via the SRB2, the UE 102 and the DU 174 use the BEARER set to 2 in the security protection as described above. When the UE 102 and DU 174 communicate DL data packets and / or UL data packets via the DRB, the UE 102 and the DU 174 use the BEARER set to a DRB identity (i.e., a value) in the security protection and operation as described above. The DRB identity identifies the DRB.

[0088] Generally, if the CU 172 verifies that a MAC-I (e.g., the second MAC-I) received from the UE 102 via the DU 174 is invalid, the CU 172 may transmit to the UE 102, via the DU 174, a release message to release the connection between the UE 102 and the BS 104. In some embodiments, the CU 172 applies security protection to the release message to generate a security-protected release message and transmits the release message to the UE 102, as described for the security mode command message. In other embodiments, the CU 172 transmits the release message to the UE 102 without applying security protection to the release message. In such embodiments, the CU 172 may deactivate the security protection for communicating data with the UE 102. In such cases, the CU 172 may generate a null MAC-I (e.g., a MAC-I that only includes “0”) and transmit a DL PDU, including the release message and the null MAC-I, to the UE 102. Thus, the UE 102 correctly retrieves the release message from the DL PDU. If the CU 172 does not include the null MAC-I in the DL PDU and the UE 102 determines that the DL PDU includes a MAC-I, the UE 102 determines a wrong end octet for the release message in the DL PDU. As a result, the UE 102 is not able to retrieve the release message from the DL PDU. In some embodiments, the DL PDU is a PDCP PDU.

[0089] In response to receiving 310 the security mode command message, the UE 102 also activates 326 the security protection for MAC CE, to securely communicate MAC CE(s) with the DU 174. In some embodiments, if the UE 102 verifies that the first MAC-I is valid, the UE 102 activates 326 the security protection.PATENT APPLICATION Attorney Docket No.: 0683-125-WOIn some embodiments, a first sublayer (e.g., RRC sublayer 212 or PDCP sublayer 208) of the UE 102 indicates a second sublayer (e.g., MAC sublayer 204) of the UE 102 to activate the security protection in 326. Otherwise, if the UE 102 verifies that the first MAC-I is invalid, the UE 102 skips event 326. Note that the security protection for the data communication is activated 312 at the PDCP layer level, while the security protection for the MAC CE is activated 326 at the MAC layer level. In other words, the security protection for the data communication is activated at a layer level higher than the MAC layer level.

[0090] After the connection establishment procedure 390, the CU 172 determines 318 to activate the security protection for communicating the MAC CE(s) with the UE 102. In one embodiment, the security protection activations 318 and 326 are synchronized in time. In another embodiment, the activation 318 happens earlier in time than the activation 326. In response to the determination 318, the CU 172 transmits 320 a second CU-to-DU message to the DU 174, for activating 322 the security protection for communicating the MAC CE(s) with the UE 102. In some embodiments, if the CU 172 verifies that the second MAC-I is valid, the CU 172 determines to activate 318 the security protection. Otherwise, if the CU 172 verifies that the second MAC-I is invalid, the CU 172 skips event 318.

[0091] In some embodiments, the DU 174 transmits a second DU-to-CU message (not shown in FIG. 3A) to the CU 172 in response to the second CU-to-DU message 320. In some embodiments, the second CU-to-DU message and the second DU-to-CU message are a UE Context Modification Request message and a UE Context Modification Response message, respectively. In other embodiments, the second CU-to-DU message and the second DU-to-CU message are F1 Application Protocol (F1AP) messages. In some embodiments, the second CU-to-DU message may be combined with the first CU-to-DU message as a single CU-to-DU message. In other embodiments, the second CU-to-DU message and the first CU-to-DU message are separate messages.

[0092] In other embodiments, before receiving the transmission 316, the CU 172 determines to activate 318 the security protection and transmits 320 the second CU-to-DU message. In such embodiments, if the CU 172 verifies that the second MAC-I is invalid, the CU 172 may transmit an additional CU-to-DU message to the DU 174, for deactivating the security protection for MAC CE(s).PATENT APPLICATION Attorney Docket No.: 0683-125-WO

[0093] After (e.g., in response to) receiving 320 the second CU-to-DU message, the DU 174 activates 322 the security protection for communicating the MAC CE(s) with the UE 102. After event 320, the DU 174 determines to transmit a first DL MAC CE. The first DL MAC CE may be related to beam management or radio resource management. The first DL MAC CE may be used to activate or deactivate radio resources. In some embodiments, the radio resources include one or more reference signal resources. In other embodiments, the radio resources include a primary secondary cell (PSCell) and / or one or more SCells configured for the UE 102. The first DL MAC CE may be a layer 1 / layer2 triggered mobility (LTM) command. The first DL MAC CE may activate or deactivate layer 1 or layer 2 measurement configuration and / or reporting. The first DL MAC CE may activate or deactivate transmission of one or more sounding reference signals (SRSs). The first DL MAC CE may be a discontinuous reception (DRX) command or a long DRX command. The first DL MAC CE may activate, deactivate, or indicate one or more Transmission Configuration Indication (TCI) states. The first DL MAC CE may activate or deactivate reception of one or more reference signals (RSs). The first DL MAC CE may update a pathloss RS. The first DL MAC CE may activate, indicate, or deactivate spatial relation for a resource set or a physical channel. The first DL MAC CE may indicate a recommended bit rate. The first DL MAC CE may include a UE ID or a UE Contention Resolution ID. The UE ID may be a radio network temporary identifier (RNTI) such as a cell RNTI, an inactive RNTI, or a RNTI unique in a RAN notification area. The first DL MAC CE may activate or deactivate a measurement gap. The first DL MAC CE may configure or update a UL transmission timing or a DL reception timing. The first DL MAC CE may be a timing advance command. The first DL MAC CE may include a parameter (e.g., Next Hop Chaining Counter parameter) for deriving one or more security keys. Note that all these possibilities for the MAC CE are not part of the communication data transmitted by the DU for which the security protection is activated in step 322.

[0094] In some embodiments, the DU 174 applies security protection to the first DL MAC CE to generate a security-protected DL MAC CE. The DU 174 then transmits 328 a first DL MAC PDU including the security-protected DL MAC CE to the UE 102. When receiving 328 the first DL MAC PDU, the UE 102 retrieves the security-protected DL MAC CE from the first DL MAC PDU. Because the UE 102 hasPATENT APPLICATION Attorney Docket No.: 0683-125-WOactivated 326 the security protection, the UE 102 performs a security operation to process the security-protected DL MAC CE to obtain a particular DL MAC CE (i.e. , the first DL MAC CE). In some implementations, the DU 174 may apply security protection to the first DL MAC CE and a first DL MAC CE subheader for the first DL MAC CE to generate a security-protected DL MAC CE. In such cases, the UE 102 performs security operation to process the first DL MAC CE subheader and the security-protected DL MAC CE to obtain a particular DL MAC CE (i.e., the first DL MAC CE). In other implementations, the DU 174 may apply security protection to only the first DL MAC CE to generate a security-protected DL MAC CE. That is, the security protection may not be applied to the first DL MAC CE subheader. In such cases, the UE 102 performs the security operation to process only the security-protected DL MAC CE to obtain a particular DL MAC CE (i.e., the first DL MAC CE).

[0095] When or after the security protection for MAC CE(s) is activated as described above, the UE 102 determines to transmit a first UL MAC CE. In some embodiments, the first UL MAC CE is related to beam management. The first UL MAC CE may be a beam report. The first UL MAC CE may be used for beam failure recovery. The first UL MAC CE may be related to radio resource management. The first UL MAC CE may be used to request radio resources. The first UL MAC CE may be a buffer status report or a delay status report. The first UL MAC CE may be a layer 1 or layer 2 measurement report. The first UL MAC CE may be a power headroom report. The first UL MAC CE may be a measurement gap request or a configured grant confirmation. The first UL MAC CE may include a UE ID. The UE ID may be a radio network temporary identifier (RNTI) such as a cell RNTI, an inactive RNTI, or a RNTI unique in a RAN notification area. The first UL MAC CE may be a timing advance report. The first UL MAC CE may be a recommended bit rate query MAC CE. The first UL MAC CE may include or be a layer 1 or layer 2 measurement report. The first UL MAC CE may be a measurement gap request MAC CE. The first UL MAC CE may be a power headroom report. Note that all these possibilities for the MAC CE transmitted by the UE are not part of the communication data transmitted by the UE, forwhich the security protection is activated in step 312. For this reason, the communication data is considered in this document to be data excluding MAC CE.PATENT APPLICATION Attorney Docket No.: 0683-125-WO

[0096] In some embodiments, the DL MAC CEs described above and / or below are MAC CEs for DL shared channel (DL-SCH) or unicast, as specified in 3GPP Technical Specification (TS) 38.321 or 3GPP 6G MAC specification. In some embodiments, the UL MAC CEs described above and / or below are MAC CEs for UL shared channel (UL-SCH) or unicast, as specified in 3GPP TS 38.321 or 3GPP 6G MAC specification.

[0097] In some embodiments, the UE 102 applies the security protection to the first UL MAC CE to generate a security-protected UL MAC CE. The UE 102 then transmits 330 a first UL MAC PDU including the security-protected UL MAC CE to the DU 174. When receiving 330 the first UL MAC PDU, the DU 174 retrieves the security-protected UL MAC CE from the first UL MAC PDU. Because the DU 174 has activated 322 the security protection, the DU 174 performs a security operation to process the security-protected UL MAC CE to obtain a particular (plain-text) UL MAC CE (i.e. , the first UL MAC CE as described above). In some implementations, the UE 102 may apply security protection to the first UL MAC CE and a first UL MAC CE subheader for the first UL MAC CE to generate a security-protected UL MAC CE. In such cases, the DU 174 performs security operation to process the first UL MAC CE subheader and the security-protected UL MAC CE to obtain a particular UL MAC CE (i.e., the first UL MAC CE). In other implementations, the UE 102 may apply security protection to only the first UL MAC CE to generate a security-protected UL MAC CE. That is, the security protection may not be applied to the first UL MAC CE subheader. In such cases, the DU 174 performs security operation to process only the security-protected UL MAC CE to obtain a particular UL MAC CE (i.e., the first UL MAC CE).

[0098] The DU 174 may perform an operation in response to or based on the first UL MAC CE. The operation may be related to one of: 1 ) if the first UL MAC CE requests radio resources, the DU 174 configures radio resources for the UE 102; 2) if the first UL MAC CE is a buffer status report or a delay status report, the DU 174 transmits one or more UL grants to the UE 102, based on the buffer status report or the delay status report; 3) if the first UL MAC CE is a layer 1 or layer 2 measurement report, the DU 174 may schedule, reconfigure, or assign radio resources for the UE 102 based on the layer 1 or layer 2 measurement report; 4) if the first UL MAC CE is a layer 1 or layer 2 measurement report, the DU 174 may transmit an LTM cellPATENT APPLICATION Attorney Docket No.: 0683-125-WOswitch command to the UE 102, based on the layer 1 or layer 2 measurement report; 5) if the first UL MAC CE is a beam report, the DU 174 may transmit a DCI or a DL MAC CE to activate, deactivate, or indicate one or more TCI states indicated in the beam report; 6) if the first UL MAC CE is beam failure recovery MAC CE, the DU 174 may switch to a beam indicated in the beam failure recovery MAC CE to communicate with the UE 102. Alternatively or additionally, the DU 174 transmits a DCI or a DL MAC CE to the UE 102, indicating a TCI state indicated in the beam failure recovery MAC CE.

[0099] In some embodiments, the security protection 326, 322 (which is related to security protection 318) includes integrity protection and the security operation associated with the security protection includes integrity check. In other embodiments, the security protection 326, 322 includes encryption and the security operation includes decryption. In yet other embodiments, the security protection includes integrity protection and encryption, and the security operation includes integrity check and decryption.

[0100] When the security protection includes integrity protection, the DU 174 generates a third MAC-I for protecting the integrity of the first DL MAC CE. In such embodiments, the security-protected (i.e. , integrity-protected) DL MAC CE includes the first DL MAC CE and the third MAC-I. In some embodiments, the DU 174 generates the third MAC-I using a second integrity key, a second integrity algorithm, and / or additional parameter(s) as described for FIG. 16B. In some embodiments, the additional parameter(s) includes a UE ID of the UE 102, a first higher layer parameter (higher than the MAC layer), DIRECTION, and / or a first logical channel identity (LCID) as described for FIG. 16B. The DIRECTION may be associated with downlink. For example, the DIRECTION (e.g., a bit) is set to 1 fordownlink.

[0101] In some embodiments, the UE ID is a RNTI (e.g., a cell RNTI). In some embodiments, the CU 172 transmits a first message to the UE 102 and the first message may include the first higher layer parameter and / or the second integrity algorithm. In one embodiment, the CU 172 may include the first higher layer parameter in the second CU-to-DU message. In another embodiment, the CU 172 may transmit another CU-to-DU message including the first higher layer parameter to the DU 174. In yet another embodiment, the DU 174 transmits a DU-to-CU message (e.g., the first DU-to-CU message or another DU-to-CU message) includingPATENT APPLICATION Attorney Docket No.: 0683-125-WOthe first higher layer parameter to the CU 172. In some embodiments, the first message is the security mode command message. In other embodiments, the first message is a message (e.g., an RRC reconfiguration message) other than the security mode command message. In such embodiments, the CU 172 may apply security protection to the first message and the UE 102 performs security operation (e.g., decryption and / or integrity check) for the first message, as described above for communicating the DL data packet.

[0102] In some embodiments, the first logical channel identity identifies the first DL MAC CE. The DU 174 includes the first logical channel identity in the first DL MAC CE subheader to identify the first DL MAC CE and includes the first DL MAC CE subheader, the first DL MAC CE, and the third MAC-I in the first DL MAC PDU. When receiving 328 the first DL MAC PDU, the UE 102 retrieves the first DL MAC CE subheader, the first DL MAC CE, and the third MAC-I from the first DL MAC PDU. The UE 102 verifies whether the first DL MAC CE is valid based on the third MAC-I. In some embodiments, the UE 102 verifies whether the third MAC-I is valid using the first DL MAC CE or a portion of the first DL MAC CE, a second integrity key (same as the second integrity key used by the BS 104), the second integrity algorithm, the first DL MAC CE subheader (e.g., the first logical channel identity), and / or additional parameter(s) as described above or for FIG. 16B.

[0103] The additional parameter(s) used by the UE 102 are the same as the additional parameter(s) used by the DU 174. If the UE 102 verifies that the third MAC-I is valid, the UE 102 performs an operation in accordance with the first DL MAC CE. For example, the operation includes the activation or deactivation in the examples of the first DL MAC CE as described above. Otherwise, if the UE 102 verifies that the third MAC-I is invalid, the UE 102 may ignore or discard the first DL MAC CE or the first DL MAC PDU.

[0104] Alternatively or additionally, the UE 102 may determine that a failure (e.g., integrity check failure) occurs and / or performs a failure recovery procedure with a BS (e.g., the CU 172 via the DU 174, the CU 172 via another DU, or BS 106) to recover the failure. The failure recovery procedure may be a connection reestablishment procedure (e.g., an RRC connection reestablishment procedure). In some embodiments, the UE 102 may determine that the failure occurs and / or performs the failure recovery procedure, only when the UE 102 receives N consecutive invalidPATENT APPLICATION Attorney Docket No.: 0683-125-WOMAC-ls for N respective DL MAC CEs. N is an integer and may be one or larger than one. In some embodiments, N is predetermined or specified in a 3GPP specification (e.g., TS 38.321 or6G MAC specification). In other embodiments, the UE 102 receives a second message configuring N from the CU 172 via the DU 174. The second message may be the security mode command message, the first message, or an RRC reconfiguration message. In some embodiments, the CU 172 applies the security protection to the second message and the UE 102 performs the security operation (e.g., decryption and / or integrity check) for the second message, as described above for the DL data packet.

[0105] When the security protection includes integrity protection, the UE 102 generates a fourth MAC-I for protecting the integrity of the first UL MAC CE. In such embodiments, the security-protected UL MAC CE includes the first UL MAC CE and the fourth MAC-I. In some embodiments, the UE 102 generates the fourth MAC-I using the second integrity key, the second integrity algorithm, and / or additional parameter(s) as described for FIG. 16B. In some embodiments, the additional parameter(s) include a UE ID of the UE 102, a second higher layer parameter, DIRECTION, and / or a second logical channel identity (LCID) as described for FIG.16B. The DIRECTION may be associated with the uplink. For example, the DIRECTION (e.g., a bit) is set to 0 for the uplink. In some embodiments, the UE ID is a RNTI (e.g., a cell RNTI). The first message may include the second higher layer parameter. In one embodiment, the second higher layer parameter is different from the first higher layer parameter. The first message may include the second higher layer parameter. In another embodiment, the second higher layer parameter is the first higher layer parameter. In some embodiments, the second logical channel identity identifies the first UL MAC CE. The UE 102 includes the second logical channel identity in the first UL MAC CE subheader to identify the first UL MAC CE and includes the first UL MAC CE subheader, the first UL MAC CE, and the fourth MAC-I in the first UL MAC PDU.

[0106] When receiving 330 the first UL MAC PDU, the DU 174 retrieves the first UL MAC CE subheader, the first UL MAC CE, and the fourth MAC-I from the first UL MAC PDU. The DU 174 verifies whether the first UL MAC CE is valid based on the fourth MAC-I. In some embodiments, the DU 174 verifies whether the fourth MAC-I is valid using the first UL MAC CE or a portion of the first UL MAC CE, the secondPATENT APPLICATION Attorney Docket No.: 0683-125-WOintegrity key (same as the second security key used by the UE 102), the second integrity algorithm, the first UL MAC CE subheader (e.g., the second logical channel identity), and / or additional parameter(s) as described above or for FIG. 16B.Generally, the additional parameter(s) used by the DU 174 are the same as the additional parameter(s) used by the UE 102.

[0107] If the DU 174 verifies that the fourth MAC-I is valid, the DU 174 performs an operation in accordance with the first UL MAC CE. Otherwise, if the DU 174 verifies that the fourth MAC-I is invalid, the DU 174 may ignore or discard the first UL MAC CE or the first UL MAC PDU. Alternatively or additionally, the DU 174 may determine that a failure (e.g., integrity check failure) occurs and transmits a DU-to-CU message indicating the failure to the CU 172. In response to receiving the failure indication from the DU 174, the CU 172 may transition the UE 102 to the idle state. In some embodiments, the DU 174 may indicate the failure to the CU 172, only when the DU 174 receives M consecutive invalid MAC-ls for M respective UL MAC CEs. M is an integer and may be one or larger than one. In some embodiments, M is predetermined or preconfigured by the DU 174. In some alternative embodiments, the DU 174 receives the value “M”from the CU 172. In other embodiments, the CU 172 may transition the UE 102 to the idle state, only when the CU 172 receives N consecutive failure indications from the DU 174. N is an integer and may be one or larger than one. In some embodiments, N is predetermined or preconfigured by the CU 172.

[0108] In some embodiments, the second integrity algorithm is different from the first integrity algorithm. In other embodiments, the second integrity algorithm is the same as the first integrity algorithm. The second integrity algorithm may be a 64-bit algorithm or a 128-bit algorithm. The first integrity algorithm may be a 128-bit algorithm, 256-bit algorithm, or a 512-bit algorithm.

[0109] In some embodiments, the first integrity key and the second integrity key are the same. In other embodiments, the first integrity key and the second integrity key are different. The first integrity key may be a 128-bit key, a 256-bit key, or a 512-bit key. The second integrity key may be a 64-bit key ora 128-bit key. In some embodiments, the CU 172 derives the second integrity key from the first integrity key. For example, the CU 172 derives the second integrity key using the first integrity key, an ID of the second integrity algorithm, and / or one or more parameters. The CUPATENT APPLICATION Attorney Docket No.: 0683-125-WO172 includes the second integrity key in the second CU-to-DU message. In some alternative embodiments, the CU 172 includes the first integrity key, the ID of the second integrity algorithm, and / or the one or more parameters in the second CU-to-DU message. The DU 174 derives the second integrity key using the first integrity key, the ID of the second integrity algorithm, and / or the one or more parameters. Likewise, the UE 102 derives the second integrity key using the first integrity key, the ID of the second integrity algorithm, and / or the one or more parameters.

[0110] In other embodiments, the CU 172 derives the second integrity key from the first base key. For example, the CU 172 derives the second integrity key using the first base key, the ID of the second integrity algorithm, and / or one or more parameters. The CU 172 includes the second integrity key in the second CU-to-DU message. In some alternative embodiments, the CU 172 includes the first base key, the ID of the second integrity algorithm, and / or the one or more parameters in the second CU-to-DU message. The DU 174 derives the second integrity key using the first base key, the ID of the second integrity algorithm, and / or the one or more parameters. Likewise, the UE 102 derives the second integrity key using the first base key, the ID of the second integrity algorithm, and / or the one or more parameters.

[0111] In some embodiments, the one or more parameters for deriving the second integrity key include a UE ID of the UE 102. For example, the UE ID is a RNTI (e.g., cell RNTI). In other embodiments, the one or more parameters include a number or a counter.

[0112] In some embodiments, the first message may include the ID of the second integrity algorithm and / or the one or more parameters. In alternative embodiments, the UE 102 receives the second integrity key from the CU 172. For example, the first message includes the second integrity key.

[0113] When the security protection includes encryption, the DU 174 encrypts the first DL MAC CE to obtain an encrypted DL MAC CE. In such embodiments, the security-protected DL MAC CE includes the encrypted DL MAC CE. In some embodiments, the DU 174 encrypts the first DL MAC CE using a second encryption key, a second encryption algorithm, and / or additional parameter(s) as described for FIG. 17B. In some embodiments, the additional parameter(s) include a UE ID of the UE 102, a third higher layer parameter, DIRECTION, and / or the first logical channelPATENT APPLICATION Attorney Docket No.: 0683-125-WOidentity (LCID) as described for FIG. 17B. The DIRECTION may be associated with the downlink. For example, the DIRECTION (e.g., a bit) is set to 1 for the downlink. In some embodiments, the UE ID is a RNTI (e.g., a cell RNTI). The first message may include the third higher layer parameter. Alternatively, the third higher layer parameter is the first higher layer parameter. The DU 174 includes the first DL MAC CE subheader and the encrypted DL MAC CE in the first DL MAC PDU. When receiving 328 the first DL MAC PDU, the UE 102 retrieves the first DL MAC CE subheader and the encrypted DL MAC CE from the first DL MAC PDU. The UE 102 decrypts the encrypted DL MAC CE to obtain a first (decrypted) DL MAC CE, using a second encryption key (same as the second encryption key used by the BS 104), the second encryption algorithm, the first DL MAC CE subheader (e.g., the first logical channel identity), and / or additional parameter(s) as described above. Generally, the additional parameter(s) used by the UE 102 are the same as the additional parameter(s) used by the DU 174. The UE 102 applies the first (decrypted) DL MAC CE.

[0114] In some embodiments, based on the received first DL MAC CE, the UE 102 performs an operation in accordance with the first (decrypted) DL MAC CE. Depending on the first DL MAC CE as described in the examples of the first DL MAC CE, the operation may include 1) activating or deactivating the radio resources, TCI state(s), transmission of the SRS(s), reception of the RS(s), the layer 1 or layer 2 measurement configuration and / or reporting, or a measurement gap; 2) updating the pathloss RS or UL transmission timing; 3) entering or applying the DRX; 4) activating, applying or deactivating the spatial relation for a resource set or physical channel; 5) applying the recommended bit rate; or 6) applying the UE ID in communication with the DU 174 and / or the CU 172.

[0115] When the security protection includes encryption and integrity protection, the DU 174 generates the third MAC-I as described above. In some embodiments, the DU 174 encrypts the integrity-protected DL MAC CE to obtain an encrypted, integrity-protected DL MAC CE, e.g., using the second encryption key, the second encryption algorithm, and / or the additional parameter(s). In such embodiments, the security-protected DL MAC CE includes the encrypted, integrity-protected DL MAC CE. The DU 174 includes the first DL MAC CE subheader and the encrypted, integrity-protected DL MAC CE in the first DL MAC PDU. When receiving 328 thePATENT APPLICATION Attorney Docket No.: 0683-125-WOfirst DL MAC PDU, the UE 102 retrieves the first DL MAC CE subheader and the encrypted, integrity-protected DL MAC CE from the first DL MAC PDU. The UE 102 decrypts the encrypted, integrity-protected DL MAC CE to obtain a first (decrypted) integrity-protected DL MAC CE, using a second encryption key (same as the second encryption key used by the DU 174), the second encryption algorithm, the first DL MAC CE subheader (e.g., the first logical channel identity), and / or additional parameter(s) as described above. Generally, the additional parameter(s) used by the UE 102 are the same as the additional parameter(s) used by the DU 174. The UE 102 verifies the third MAC-I as described above. Based on a verification result of the third MAC-I, the UE 102 may perform actions as described above.

[0116] Alternatively, when the security protection includes encryption and integrity protection, the DU 174 obtains the encrypted DL MAC CE as described above and then generates a fifth MAC-I for the encrypted DL MAC CE as described for the third MAC-I. In such cases, the DU 174 includes the encrypted DL MAC CE and the fifth MAC-I in the first DL MAC PDU. The UE 102 verifies the fifth MAC-I as described for the third MAC-I. If the UE 102 verifies that the fifth MAC-I is valid, the UE 102 decrypts the encrypted DL MAC CE as described above. Otherwise, if the UE 102 verifies that the fifth MAC-I is invalid, the UE 102 may ignore or discard the first DL MAC CE or the first DL MAC PDU. Alternatively or additionally, if the UE 102 verifies that the fifth MAC-I is invalid, the UE 102 may determine that a failure (e.g., integrity check failure) occurs and / or performs a failure recovery procedure (e.g., an RRC connection reestablishment procedure) to recover the failure as described above.

[0117] When the security protection includes encryption, the UE 102 encrypts the first UL MAC CE to obtain an encrypted UL MAC CE. In such embodiments, the security-protected UL MAC CE includes the encrypted UL MAC CE. In some embodiments, the UE 102 encrypts the first UL MAC CE using a second encryption key, a second encryption algorithm, and / or additional parameter(s). In some embodiments, the additional parameter(s) includes a UE ID of the UE 102, a fourth higher layer parameter, DIRECTION, and / or the second logical channel identity (LCID) as described with regard to FIG. 17B. The DIRECTION may be associated with the uplink. For example, the DIRECTION (e.g., a bit) is set to 0 for the uplink. In some embodiments, the UE ID is a RNTI (e.g., a cell RNTI). The first message mayPATENT APPLICATION Attorney Docket No.: 0683-125-WOinclude the fourth higher layer parameter. Alternatively, the fourth higher layer parameter is the first, second, or third higher layer parameter.

[0118] The UE 102 includes the first UL MAC CE subheader and the encrypted UL MAC CE in the first UL MAC PDU. When receiving 330 the first UL MAC PDU, the DU 174 retrieves the first UL MAC CE subheader and the encrypted UL MAC CE from the first UL MAC PDU. The DU 174 decrypts the encrypted UL MAC CE to obtain a first (decrypted) UL MAC CE, using the second encryption key (same as the second encryption key used by the UE 102), the second encryption algorithm, the first UL MAC CE subheader (e.g., the second logical channel identity), and / or additional parameter(s) as described above. Generally, the additional parameter(s) used by the UE 102 are the same as the additional parameter(s) used by the DU 174. The DU 174 then performs the operation in accordance with the first (decrypted) UL MAC CE as described above.

[0119] When the security protection includes encryption and integrity protection, the UE 102 generates the fourth MAC-I to obtain the integrity-protected UL MAC CE as described above. In some embodiments, the UE 102 encrypts the integrity-protected UL MAC CE to obtain an encrypted, integrity-protected UL MAC CE, e.g., using the second encryption key, the second encryption algorithm, and / or the additional parameter(s). In such embodiments, the security-protected UL MAC CE includes the encrypted, integrity-protected UL MAC CE. The UE 102 includes the first UL MAC CE subheader and the encrypted, integrity-protected UL MAC CE in the first UL MAC PDU.

[0120] When receiving 330 the first UL MAC PDU, the DU 174 retrieves the first UL MAC CE subheader and the encrypted, integrity-protected UL MAC CE from the first UL MAC PDU. The DU 174 decrypts the encrypted, integrity-protected UL MAC CE to obtain a first (decrypted) integrity-protected UL MAC CE, using a second encryption key (same as the second encryption key used by the DU 174), the second encryption algorithm, the first UL MAC CE subheader (e.g., the second logical channel identity), and / or additional parameter(s) as described above.Generally, the additional parameter(s) used by the UE 102 are the same as the additional parameter(s) used by the DU 174. The DU 174 verifies the fourth MAC-I as described above. Based on a verification result of the fourth MAC-I, the DU 174 may perform actions as described above.PATENT APPLICATION Attorney Docket No.: 0683-125-WO

[0121] Alternatively, when the security protection includes encryption and integrity protection, the UE 102 obtains the encrypted UL MAC CE as described above and then generates a sixth MAC-I for the encrypted UL MAC CE as described for the fourth MAC-I. In such cases, the UE 102 includes the encrypted UL MAC CE and the sixth MAC-I in the first UL MAC PDU. The DU 174 verifies the sixth MAC-I as described for the fourth MAC-I. Based on a verification result of the sixth MAC-I, the DU 174 performs actions as described for the fourth MAC-I.

[0122] In some embodiments, the second encryption algorithm is different from the first encryption algorithm. In other embodiments, the second encryption algorithm is the same as the first encryption algorithm. The second encryption algorithm may be a 64-bit algorithm or a 128-bit algorithm. The first encryption algorithm may be a 128-bit algorithm, 256-bit algorithm, or a 512-bit algorithm.

[0123] In some embodiments, the first encryption key and the second encryption key are the same. In other embodiments, the first encryption key and the second encryption key are different. The first encryption key may be a 128-bit key, a 256-bit key, or a 512-bit key. The second encryption key may be a 64-bit key or a 128-bit key. In some embodiments, the CU 172 derives the second encryption key from the first encryption key. For example, the CU 172 derives the second encryption key using the first encryption key, an ID of the second encryption algorithm, and / or one or more parameters. The CU 172 includes the second encryption key in the second CU-to-DU message. In some alternative embodiments, the CU 172 includes the first encryption key, the ID of the second encryption algorithm, and / or the one or more parameters in the second CU-to-DU message. The DU 174 derives the second encryption key using the first encryption key, the ID of the second encryption algorithm, and / or the one or more parameters. Likewise, the UE 102 derives the second encryption key using the first encryption key, the ID of the second encryption algorithm, and / or the one or more parameters.

[0124] In other embodiments, the CU 172 derives the second encryption key from the first base key. For example, the CU 172 derives the second encryption key using the first base key, the ID of the second encryption algorithm, and / or one or more parameters. The CU 172 includes the second encryption key in the second CU-to-DU message. In some alternative embodiments, the CU 172 includes the first base key, the ID of the second encryption algorithm, and / or the one or more parameters inPATENT APPLICATION Attorney Docket No.: 0683-125-WOthe second CU-to-DU message. The DU 174 derives the second encryption key using the first base key, the ID of the second encryption algorithm, and / or the one or more parameters. Likewise, the UE 102 derives the second encryption key using the first base key, the ID of the second encryption algorithm, and / or the one or more parameters.

[0125] In some embodiments, the one or more parameters for deriving the second encryption key include a UE ID of the UE 102. For example, the UE ID is an RNTI (e.g., cell RNTI). In other embodiments, the one or more parameters includes a number or a counter.

[0126] In some embodiments, the first message may include the ID of the second encryption protection algorithm and / or the one or more parameters. In alternative embodiments, the UE 102 receives the second encryption key from the CU 172. For example, the first message includes the second encryption key.

[0127] In some embodiments, the length of each of the MAC-ls for the MAC CEs is smaller than a length of the MAC-ls for data (e.g., the security mode command message, security mode complete, and / or data packets). In other embodiments, a length of each of the MAC-ls for the MAC CEs is equal to the length of the MAC-ls for data (e.g., the security mode command message, security mode complete, and / or data packets). In some embodiments, each of the MAC-ls for data has a length of Z bits. In some embodiments, each of the MAC-ls for the MAC CEs has a length of Y bits, with Y < Z, and Z and Y being positive integers. For example, Z is smaller than 257. In another example, Z is 32, 64, 128, or 256. For example, Y is smaller than 33. In another example, Y is 8, 10, 12, 14, 16, 18, 20, or 32.

[0128] In some embodiments, when or after the security protection for MAC CE(s) is activated as described above, the DU 174 transmits 332 to the UE 102 one or more DL MAC PDUs including non-security protected DL MAC CE. In some embodiments, the DU 174 receives 394 the DL PDU(s) from the CU and includes the DL PDU(s) in the first DL MAC PDU and / or other of the one or more DL MAC PDUs. In other embodiments, the DU 174 may transmit 394 to the UE 102 one or more other DL MAC PDUs including the DL PDU(s).

[0129] In some embodiments, when or after the security protection for MAC CE(s) is activated as described above, the UE 102 may transmit 334 to the DU 174 one or more UL MAC PDUs including non-security protected UL MAC CE. In somePATENT APPLICATION Attorney Docket No.: 0683-125-WOembodiments, the UE 102 may include, for the communication 394, the UL PDll(s) in the first UL MAC PDU and / or the one or more UL MAC PDUs. In other embodiments, the UE 102 may transmit 394 to the DU 174 one or more other UL MAC PDUs including the UL PDU(s).

[0130] In some embodiments, the communication 394 may occur before or after events 320, 328, 330, 332, or 334. In other embodiments, the communication 394 may occur together with events 320, 328, 330, 332, or 334. In some implementations, security protection for some MAC CEs may be required and specified in TS 38.321 or 3GPP 6G MAC specification and security protection for other MAC CEs may not be required as specified in a 3GPP specification (e.g., TS 38.321 or3GPP 6G MAC specification). Thus, when communicating with a MAC CE with the BS 104 (e.g., the DU 174), the UE 102 can determine whether to apply security protection or operation to the MAC CE in accordance with the 3GPP specification. Similarly, when communicating with a MAC CE with the UE 102, the DU 174 can determine whether to apply security protection or operation to the MAC CE in accordance with the 3GPP specification.

[0131] In other implementations, the CU 172 can include a configuration in the first message, a security activation command (as described for Fig. 3B), ora CU-to-UE message (as described for Fig. 3C), where the configuration configures security protection for some MAC CEs. The CU 172 may include a configuration in the CU-to-DU message 320, configuring security protection for the MAC CEs. If the CU 172 does not configure the UE 102 and the DU 174 to apply security protection for a particular MAC CE, the DU 174 and the UE 102 determine no security protection is configured for the MAC CE. Thus, when communicating with a MAC CE with the BS 104, the UE 102 can determine whether to apply security protection or operation to the MAC CE in accordance with the configuration. Similarly, when communicating with a MAC CE with the UE 102, the BS 104 can determine whether to apply security protection or operation to the MAC CE in accordance with the configuration.

[0132] FIG. 3B depicts a scenario 300B, similar to the scenario 300A, in which the DU 174 instructs the UE 102 to activate the security protection for the MAC CE. More specifically, a difference between the scenarios 300B and 300A is that the DU 174 transmits 324 to the UE 102 a security activation command for specifically activating security protection for the MAC CE. The DU 174 transmits 324 the securityPATENT APPLICATION Attorney Docket No.: 0683-125-WOactivation command MAC CE in response to receiving 320 the first CU-to-DU message or activating 322 the security protection for MAC CE(s). The UE 102 activates 326 the security protection in response to the security activation command MAC CE. In some embodiments, the UE 102 transmits a security activation confirm MAC CE to the DU 174 to confirm the reception of the security activation command MAC CE.

[0133] In some embodiments, the DU 174 applies security protection to the security activation command MAC CE to obtain a security-protected security activation command MAC CE, similar to applying security protection to the first DL MAC CE as described for FIG. 3A. In some embodiments, a logical channel identity identifies the security activation command MAC CE. The BS 104 may generate a MAC CE subheader including the logical channel identity and includes the MAC CE subheader and the security-protected security activation command MAC CE in a DL MAC PDU. The DU 174 transmits 324 the DL MAC PDU to the UE 102. When receiving 324 the DL MAC PDU, the UE 102 retrieves the MAC CE subheader and the security-protected security activation command MAC CE from the DL MAC PDU and performs a security operation (e.g., decryption and / or integrity check) for the security-protected security activation command MAC CE, similar to retrieving and performing security operation for the first DL MAC CE as described for FIG. 3A.

[0134] If the UE 102 obtains a valid security activation command MAC CE (i.e., the same as the security activation command MAC CE generated by the DU 174) as a result of the security operation, the UE 102 activates 326 security protection for MAC CE(s). Otherwise, if the UE 102 obtains an invalid security activation command MAC CE, the UE 102 may ignore or discard the security activation command MAC CE. Alternatively or additionally, if the UE 102 obtains an invalid security activation command MAC CE, the UE 102 may determine that a failure occurs and / or performs a failure recovery procedure to recover the failure as described for FIG. 3A.

[0135] In some embodiments, the UE 102 may perform security protection for the security activation confirmation MAC CE, similar to performing security protection for the first UL MAC CE as described for FIG. 3A. In some embodiments, a logical channel identity identifies the security activation confirmation MAC CE. The UE 102 may generate a MAC CE subheader including the logical channel identity and includes the MAC CE subheader and the security-protected security activationPATENT APPLICATION Attorney Docket No.: 0683-125-WOconfirmation MAC GE in a UL MAC PDU. The UE 102 transmits the UL MAC PDU to the DU 174.

[0136] When receiving the UL MAC PDU, the DU 174 retrieves the MAC CE subheader and the security-protected security activation confirmation MAC CE from the UL MAC PDU and performs security operation (e.g., decryption and / or integrity check) for the security-protected security activation response MAC CE, similar to retrieving and performing security operation for the first UL MAC CE as described for FIG. 3A. If the DU 174 obtains a valid security activation confirmation MAC CE (i.e., the same as the security activation confirmation MAC CE generated by the UE 102) as a result of the security operation, the DU 174 determines that the DU 174 successfully instructed the UE 102 to activate the security protection for the MAC CE(s). Otherwise, if the DU 174 obtains an invalid security activation response MAC CE as a result of the security operation, the DU 174 may determine that the security activation at the UE 102 failed.

[0137] In one embodiment, the DU 174 retransmits the security-protected security activation command MAC CE as described above. In another embodiment, the DU 174 performs again security protection for the security activation command MAC CE to obtain a new security-protected security activation command MAC CE as described above. The DU 174 transmits the new security-protected security activation command MAC CE to the UE 102 in another UL MAC PDU, as described above. Alternatively, the DU 174 may determine that a failure (e.g., integrity check failure) occurred and transmits a DU-to-CU message indicating the failure to the CU 172. In response to receiving the failure indication from the DU 174, the CU 172 may transition the UE 102 to the idle state.

[0138] In some embodiments, the security activation command MAC CE includes a parameter(s) for deriving the second integrity key and / or the second encryption key as described for FIG. 3A. In other alternative embodiments, the security activation command MAC CE does not include a parameter(s) for deriving the second integrity key and / or the second encryption key. In the alternative embodiments, the UE 102 derives the second integrity key and / or the second encryption key as described for FIG. 3A. Likewise, the BS 104 derives the second integrity key and / or the second encryption key as described for FIG. 3A.PATENT APPLICATION Attorney Docket No.: 0683-125-WO

[0139] In some embodiments, the security activation command MAC CE includes a parameter(s) for performing security protection (e.g., integrity protection and / or encryption) for MAC CE(s) and / or performing a security operation (e.g., integrity check and / or decryption) for MAC CE(s) as described for FIG. 3A. In other alternative embodiments, the security activation command does not include parameter(s) for performing the security protection (e.g., integrity protection and / or encryption) for MAC CE(s) and / or performing the security operation (e.g., integrity check and / or decryption) for MAC CE(s). Instead, the parameter(s) may be included in the security mode command message. In some embodiments, the UE 102 may perform the security protection (e.g., integrity protection and / or encryption) for UL MAC CE(s) and / or perform the security operation (e.g., integrity check and / or decryption) for the received DL MAC CE(s), as described for FIG. 3A. Likewise, the DU 174 may perform the security protection (e.g., integrity protection and / or encryption) for DL MAC CE(s) and / or perform the security operation (e.g., integrity check and / or decryption) for the received UL MAC CE(s), as described for FIG. 3A.

[0140] FIG. 3C depicts a scenario 300C, similar to the scenario 300A, but the CU instructs each of the DU and UE to activate the security protection for MAC CE. The differences between the scenarios 300C and 300A are as follows. In response to the determination 318, the CU 172 generates a CU-to-UE message to activate the security protection for MAC CE(s). The CU 172 transmits 323 to the DU 174 a CU-to-DU message including the CU-to-UE message. In some embodiments, the CU-to-DU message 323 is in addition to the CU-to-DU message transmitted 320 by the CU 172 to the DU 174 to activate 322 at the DU the security protection for MAC CE(s). The DU 174, in response to the CU-to-DU message received in 323, transmits 336 to the UE 102 the CU-to-UE message. The UE 102 activates 326 the security protection in response to the received CU-to-UE message. In some embodiments, the message 320 and the message 323 can be combined as a single CU-to-DU message. In other embodiments, the messages 320 and 323 are different messages.

[0141] Examples of the security protection determined by the security mode command message or the DL data packet as described for FIG. 3A may apply to the CU-to-UE message. Depending on the scenario, the UE 102 may or may not transmit a UE-to-CU message to the CU 172 in response to the CU-to-UE messagePATENT APPLICATION Attorney Docket No.: 0683-125-WO336. In some embodiments, the CU-to-UE message and the UE-to-CU message are a security activation command message and a security activation response message, respectively. In some embodiments, the CU-to-UE message and the UE-to-CU message are RRC messages (e.g., RRC reconfiguration message and RRC reconfiguration complete message, respectively).

[0142] In some embodiments, the CU 172 receives, from the DU 174, a DU-to-CU message including a configuration for activating the security protection for MAC CE(s) and includes the configuration in the CU-to-UE message. In such cases, the DU 174 generates the configuration and the CU 172 includes the configuration in the CU-to-UE message. In some embodiments, the DU 174 transmits the DU-to-CU message (e.g., the second DU-to-CU message described for FIG. 3A) to the CU 172 in response to the CU-to-DU message 320. In some alternative embodiments, the CU 172 generates the configuration and includes the configuration in the CU-to-UE message.

[0143] In some embodiments, the CU 172 may apply the security protection (e.g., integrity protection and / or encryption) to the CU-to-UE message to obtain a security-protected CU-to-UE message, similar to applying security protection to the security mode command message or DL data packet as described for FIG. 3A. The CU 172 transmits 323 to the DU 174 the CU-to-DU message including the security-protected CU-to-UE message. The DU 174 in turn transmits 336 the CU-to-UE message to the UE 102. When receiving 336 the security-protected CU-to-UE message, the UE 102 performs a security operation for the security-protected CU-to-UE message to obtain the CU-to-UE message, similar to performing security operation for the DL data packet as described for FIG. 3A.

[0144] In some embodiments, if the UE 102 determines that the integrity (e.g., a MAC-I) for the CU-to-UE message is invalid, the UE 102 may transmit a security activation failure message to the CU 172, via the DU 174. In some embodiments, descriptions for the security mode failure message may apply to the security activation failure message. Alternatively, if the UE 102 verifies that the integrity (e.g., a MAC-I) for the CU-to-UE message is invalid, the UE 102 determines a failure (e.g., integrity check failure) and performs a failure recovery procedure to recover the failure, as described above.PATENT APPLICATION Attorney Docket No.: 0683-125-WO

[0145] Otherwise, if the UE 102 verifies that the integrity (e.g., a MAC-I) for the CU-to-UE message is valid, the UE 102 activates 326 the security protection for the MAC CE(s), as described above. In some embodiments, the UE 102 performs security protection for the UE-to-CU message to obtain a security-protected UE-to-CU message, as described for transmitting the security mode complete message or UL data packet for FIG. 3A. The UE 102 transmits the security-protected UE-to-CU message to the CU 172, via the DU 174. The CU 172 receives the security-protected UE-to-CU message and performs a security operation (e.g., decryption and / or integrity check) for the security-protected UE-to-CU message to obtain the UE-to-CU message, as described for receiving and obtaining the security mode complete or UL data packet for FIG. 3A. In some embodiments, if the CU 172 verifies that the integrity for the UE-to-CU message is valid, the CU 172 may determine to activate 318 the security protection for MAC CE(s), as described for FIG. 3A. Otherwise, if the CU 172 verifies that the integrity for the UE-to-CU message is invalid, the CU 172 may skip events 318 and 320 and / or transmit a release message to the UE 102, via the DU 174, to release the connection between the UE 102 and the BS 104 as described for FIG. 3A.

[0146] In some embodiments, the CU-to-UE message includes a parameter(s) for deriving the second integrity key and / or the second encryption key, as described for FIG. 3A. In other alternative embodiments, the CU-to-UE message does not include the parameter(s) for deriving the second integrity key and / or the second encryption key. In some embodiments, the UE 102 derives the second integrity key and / or the second encryption key as described for FIG. 3A. Likewise, the CU 172 derives the second integrity key and / or the second encryption key as described for FIG. 3A.

[0147] In some embodiments, the CU-to-UE message includes parameter(s) for performing a security protection (e.g., integrity protection and / or encryption) for MAC CE(s) and / or performing a security operation (e.g., integrity check and / or decryption) for MAC CE(s), as described for FIG. 3A. In other alternative embodiments, the CU-to-UE message does not include parameter(s) for performing the security protection (e.g., integrity protection and / or encryption) for MAC CE(s) and / or performing the security operation (e.g., integrity check and / or decryption) for MAC CE(s). In some embodiments, the UE 102 may perform the security protection (e.g., integrity protection and / or encryption) for UL MAC CE(s) and / or perform the securityPATENT APPLICATION Attorney Docket No.: 0683-125-WOoperation (e.g., integrity check and / or decryption) for the received DL MAC CE(s), as described for FIG. 3A. Likewise, the DU 174 may perform the security protection (e.g., integrity protection and / or encryption) for DL MAC CE(s) and / or perform the security operation (e.g., integrity check and / or decryption) for the received UL MAC CE(s), as described for FIG. 3A.

[0148] While FIGs. 3A to 3C presented various scenarios in which the CU makes the decision to activate the security protection for MAC CE(s), FIGs. 4A to 4C introduce various scenarios in which the DU makes this decision. Many of the acts, events, or steps illustrated in FIGs. 3A to 3C and discussed above are repeated in the embodiments of FIGs. 4A to 4C, and thus, their description is omitted here. Only the new or modified steps are discussed with regard to FIGs. 4A to 4C.

[0149] FIG. 4A depicts a scenario 400A in which the DU makes the decision to activate the security protection for the MAC CE(s) and the DU instructs the UE to activate the security protection for the MAC CE(s). For this scenario, the DU does not inform the CU about the above decision, i.e., the CU is not involved in the activation of the security protection of the MAC CE(s). More specifically, after or before the CU 172 activated 306 the security protection for the data excluding the MAC CE(s), the DU 174 determines 417 to activate the security protection for the MAC CE(s). The DU 174 activates 322 the security protection for the MAC CE(s) and then transmits 324 a security activation command to the UE 102 with instructions for activating the security protection for MAC CE(s). In response to this command, the UE 102 activates 326 the security protection for MAC CE(s) and then starts communicating 328, 330 security protected MAC CE(s) with the DU.

[0150] FIG. 4B depicts a scenario 400B in which the DU still makes the decision to activate the security protection for MAC CE(s), but requests the CU to confirm the decision, and the CU informs the UE about the command to activate the security protection for MAC CE(s). More specifically, after the DU 174 determines 417 to activate the security protection for MAC CE(s), the DU 174 transmits 419 a DU-to-CU message to the CU 172 requesting permission to activate the security protection for MAC CE(s). In response to this message, the CU 172 transmits 323 a first CU-to-DU message, including a CU-to-UE message for the UE for activating the security protection for MAC CE(s), and transmits 425 a second CU-to-DU message to the DU 174, approving the activation of the security protection for MAC CE(s) at the DU. ThePATENT APPLICATION Attorney Docket No.: 0683-125-WODU 174 transmits 336 a CU-to-UE message, to activate the security protection for MAC CE(s) at the UE 102, and the UE 102 activates 326 the security protection for MAC CE(s). In response to the message received in step 425, the DU 174 activates 322 the security protection for MAC CE(s). Afterwards, the MAC CE(s) communicated between the UE 102 and DU 174 may be security protected, depending on their types, which were discussed above.

[0151] FIG. 4C depicts a scenario 400C in which the DU determines to activate the security protection for MAC CE(s) and provides to the CU a configuration to activate, at the UE, the security protection for MAC CE(s). More specifically, after the DU 174 determines 417 to activate the security protection for MAC CE(s), the DU 174 transmits 421 to the CU 172 a DU-to-CU message that includes a UE configuration for the UE to apply the security protection for MAC CE(s). In response to this message, the CU 172 generates a CU-to-UE message including the UE configuration for the security protection for MAC CE(s) and transmits 423 a CU-to-DU message including the CU-to-UE message to the DU 174. The DU 174 transmits 436 the CU-to-UE message to the UE 102, and the UE 102, upon receiving the UE configuration, activates 326 the security protection for MAC CE(s). In some embodiments, the CU 172 transparently includes the UE configuration in the CU-to-UE message. Afterwards, the MAC CE(s) communicated between the UE 102 and DU 174 may be security protected, depending on their types, which were discussed above.

[0152] Next, several example methods, which may be performed in a RAN node (e.g., the CU 172 or DU 174) or the UE, are discussed with reference to FIGs. SA-15. Descriptions and scenarios described for FIGs. 3A-4C may apply to any of the FIGs. 5A-15. In all the following methods, when referring to a UE, CU, and DU, they may be the UE 102, CU 172, and DU 174 in FIGs. 1Aand 1B. The UE, CU, and DU may also refer to other corresponding network elements or entities (e.g., a CU that may be integrated in the CN of a 6G system, instead of being part of the RAN node as in a 5G system).

[0153] FIG. 5A illustrates an example method 500A, which may be performed by a DU (e.g., the DU 174). The method 500A includes steps described in the scenario 300A. The method 500A begins with block 590 where the DU communicates with a UE and a CU. At block 520, the DU receives a CU-to-DU message from the CU,PATENT APPLICATION Attorney Docket No.: 0683-125-WOactivating security protection for communicating MAC CE(s) with the UE. At block 524, the DU optionally transmits a security activation command to the UE, activating security protection for communicating MAC CE(s). At block 522A, the DU activates security protection for communicating MAC CE(s) with the UE in response to the CU-to-DU message received at 520. At block 529, the DU communicates security-protected MAC CEs with the UE (e.g., events 328 and / or 330). As previously discussed with regard to FIGs. 3A to 3C (which also applies to FIGs. 4A to 4C), at block 533, the DU may communicate non-security-protected MAC CEs with the UE (e.g., events 302, 304, 332, and / or 334). In one embodiment, the type of the MAC CE determines whether the MAC CE is communicated in a secure or non-secure mode. Block 533 may occur before, during or after any other block described in this method.

[0154] FIG. 5B is a flow diagram of an example method 500B, performed at the DU and similar to the method 500A, except that the method 500B includes blocks 517 and 522B instead of blocks 520 and 522A. The method 500B includes blocks described in the scenario 400A. At block 517, the DU determines (e.g., event 417) to activate the security protection for communicating the MAC CE(s) with the UE. At block 524, the DU transmits (e.g., event 424) a security activation command to the UE 102. Note that this transmission is not optional, as in the method 500A. At block 522B, the DU activates (e.g., event 422) the security protection for communicating MAC CE(s) with the UE, in response to the determination 517. In some embodiments, in response to the block 517 or 522B, the DU transmits a DU-to-CU message to the CU, indicating the security protection for communicating MAC CEs with the UE is activated. In some embodiments, the DU receives a security activation confirmation from the UE, indicating that the UE 102 received the security activation command. At block 522B, the DU may activate the security activation in response to block 524 or after receiving the security activation confirmation from the UE or CU. Blocks 529 and 533 are the same as in FIG. 5A.

[0155] FIG. 5C is a flow diagram of an example method 500C similar to the methods 500A and 500B, except that the method 500C includes blocks 519 and 525 instead of blocks 520 and 524. The method 500C includes steps described in the scenario 400B. At block 519, the DU transmits a DU-to-CU message to the CU, requesting to activate security protection for communicating MAC CE(s) with the UE.PATENT APPLICATION Attorney Docket No.: 0683-125-WOAt block 525, the DU receives (e.g., event 425) a CU-to-DU message from the CU, confirming to activate security protection for communicating MAC CE(s) with the UE. The DU also receives (see event 323 in FIG. 4B) a CU-to-DU message for informing the UE to activate its security protection for the MAC CE(s), and the DU then transmits (see event 336 in FIG. 4B) the CU-to-UE message.

[0156] FIG. 5D is a flow diagram of an example method 500D similar to the methods 500A-500C, except that the method 500D includes block 521 instead of block 524. The method 500D includes steps described in the method of FIG. 4C. At block 521 , the DU transmits a configuration to the UE, via the CU, where the configuration activates the security protection for communicating the MAC CE(s) (e.g., events 421 , 423, and 436).

[0157] FIG. 5E illustrates an example method 500E similar to the methods 500A-500D, except that the method 500E includes block 542. The method 500E includes steps from the methods of FIGs. 4A to 4C. At block 542, the DU determines whether the UE and / or the DU supports security protection for MAC CE(s). If the UE and / or the DU support security protection for MAC CE(s) (i.e., “Yes” branch of block 542), the flow proceeds to blocks 519, 525, and 522A (see FIG. 5C), or blocks 517, 524, 522B (see FIG. 5B), or blocks 517, 521 , or 522B (see FIG. 5D). At block 529, the DU communicates security-protected MAC CEs with the UE. Otherwise, if the UE and / or the DU do not support security protection for MAC CE(s) (i.e., “No” branch of block 542), the flow proceeds to block 533. The flow proceeds to block 533 from block 542 as well as from block 529. In some embodiments, “the UE and / or the DU” in block 542 may be replaced by “the UE”, “the DU” or “the UE and the DU”.

[0158] FIGs. 6A to 6E discuss similar scenarios as those discussed above with regard to FIGs. 5A to 5E, but from the perspective of the CU.

[0159] FIG. 6A illustrates an example method 600A, which may be performed by a CU (e.g., the CU 172). The method 600 includes steps from the methods illustrated in FIGs. 3A and 3C. The method 600A begins at block 608, with the CU transmitting a security mode command message to a UE, via a DU, for activating security protection for data communication with the UE. At block 616, the CU receives a security mode complete message from the UE via the DU. The method 600A may proceed to block 620 (following the method 300A) and / or to block 623A (following method 300C). At block 620, the CU transmits a CU-to-DU message to the DU (e.g.,PATENT APPLICATION Attorney Docket No.: 0683-125-WOevent 320), activating at the DU the security protection for communicating MAC CE(s) with the UE. At block 623A, the CU transmits (e.g., event 323) a CU-to-UE message to the UE, via the DU, for activating the security protection for communicating the MAC CE(s). Both blocks 620 and 623A proceed to block 694 where the CU communicates the security-protected data with the UE via the DU. The data in this step excludes the MAC CE(s).

[0160] FIG. 6B is a flow diagram of an example method 600B similar to the method 600A, except that the method 600B includes blocks 619 and 625 instead of block 620. Method 600B includes steps from method 400B. At block 619, the CU receives (e.g., event 419) a DU-to-CU message from the DU, requesting to activate security protection for communicating MAC CE(s) with the UE. At block 625, the CU transmits (e.g., event 425) a CU-to-DU message to the DU, confirming to activate the security protection for communicating MAC CE(s) with the UE. In one embodiment, the block 619 takes place after the DU determined to activate the security protection of the MAC CE(s). In one embodiment, the CU also transmits (see event 423) the CU-to-DU message.

[0161] FIG. 6C is a flow diagram of an example method 600C similar to the method 600A, except that the method 600C includes blocks 621 and 623C instead of blocks 620 and 623A. The method 600C includes steps similar to steps of the method 400C. At block 621, the CU receives (e.g., event 421) a DU-to-CU message from the DU, including a configuration activating the security protection for communicating MAC CE(s) with the UE. At block 623C, the CU transmits (see step 423 in FIG. 4C) a CU-to-UE message to the UE via the DU, including the configuration. Blocks 621 and 623 take place after the DU determined 417 to activate the security protection for the MAC CE(s). In one embodiment, the blocks 621 and 623 take place before the DU activates the security protection for the MAC CE(s). In another embodiment, the blocks 621 and 623 take place after the DU activates the security protection for the MAC CE(s).

[0162] FIG. 6D illustrates an example method 600D, which may be performed by a CU. The method 600D begins with blocks 608, 616, and 694, which were discussed above. At block 643, the CU determines whether the UE and / or the CU support security protection for MAC CE(s). If the UE and / or the CU support security protection for MAC CE(s) (i.e., “Yes” branch of block 643), the method proceeds toPATENT APPLICATION Attorney Docket No.: 0683-125-WOblocks 620 and / or 623A or blocks 620, 621 and 623C. Otherwise, if the UE and / or the CU do not support security protection for MAC CE(s) (i.e. , “No” branch of block 643), the method proceeds to block 644, where the method ends.

[0163] FIG. 6E is a flow diagram of an example method 600E similar to the methods 600A-600D, except that the method 600E includes block 646. The method may begin with one of the blocks 608, 616, and 694 and proceeds to blocks 619 or 621 , and 643 described above. If the UE and / or the CU support security protection for MAC CE(s) (i.e., “Yes” branch of block 643), the method proceeds to blocks 623A and / or 625 or block 623C. Otherwise, if the UE and / or the CU do not support security protection for MAC CE(s) (i.e., “No” branch of block 643), the method continues with block 646 where the CU transmits a CU-to-DU message to the DU, rejecting to activate security protection for MAC CE(s).

[0164] FIGs. 7A and 7B illustrate various DU-based scenarios for deriving or obtaining a security key for applying the security protection to the MAC CE(s). FIG.7A illustrates an example method 700A, which may be performed by a DU (e.g., the DU 174). The method 700A begins at block 590. At block 720A, the DU receives a CU-to-DU message from the CU, including at least one security parameter for secure communication of the MAC CE(s) with the UE. At block 722, the DU derives at least one security key based on the at least one security parameter received in block 720A. At block 729, the DU communicates security-protected MAC CEs with the UE, using the at least one security key (e.g., events 328 and / or 330). At block 733, the DU communicates non-security-protected MAC CEs with the UE (e.g., events 302, 304, 332, and / or 334). Block 733 may occur before, during, or after any block described above.

[0165] In some embodiments, the DU derives the at least one security key (i.e., at least one first security key) using at least one key derivation function. In one embodiment, if the at least one first security key includes a first integrity key, the DU derives the first integrity key using a first key derivation function. In another embodiment, if the at least one first security key includes a first encryption key, the DU derives the first encryption key using a second key derivation function.Depending on embodiments, the first key derivation function and the second key derivation function may be the same or different. In some embodiments, the at least one security parameter includes an ID of an integrity algorithm and / or an ID of anPATENT APPLICATION Attorney Docket No.: 0683-125-WOencryption algorithm. In some embodiments, the at least one security parameter includes at least one second security key. In some embodiments, the at least one second security key includes a second integrity key and / or a second encryption key. In some embodiments, the second integrity key and the second encryption key are the first integrity key and the first encryption key described for FIG. 3A. In some embodiments, the at least one second security key includes a first base key and / or a second base key. In some embodiments, the first base key and the second base key are the first base key and the second base key described for FIG. 3A.

[0166] In some embodiments, the DU derives the at least one first security key based on the at least one security parameter and one or more parameters. In some embodiments, the one or more parameters include a UE ID (e.g., a RNTI such as a cell RNTI). In other embodiments, the one or more parameters include a number or a counter. In some embodiments, the DU receives the one or more parameters from the CU. For example, the CU-to-DU message at block 720A includes the one or more parameters. In another example, the DU receives another CU-to-DU message including the one or more parameters from the CU.

[0167] FIG. 7B is a flow diagram of an example method 700B similar to the method 700A, except that the method 700B includes block 720B instead of blocks 720A and 722. At block 720B, the DU receives a CU-to-DU message from the CU, including at least one security key for the secure communication of the MAC CE(s) with the UE. In some embodiments, the CU derives the at least one security key as described for FIG. 3A or the DU of FIG. 7A.

[0168] FIGs. 8A to 8C illustrate various CU-based scenarios for deriving or obtaining a security key for applying the security protection to the MAC CE(s).

[0169] FIG. 8A illustrates an example method 800A, which may be performed by a CU (e.g., the CU 172). The method 800A begins with block 850 where the CU receives a CN-to-CU message from a CN, including at least one first security parameter for a UE. At block 806, the CU derives at least one first security key for the UE, from the at least one first security parameter. At block 894, the CU communicates security-protected data (excluding the MAC CE) with the UE via the DU, using the at least one first security key. At block 820A, the CU transmits a CU-to-DU message to the DU, including at least one second security parameter for secure communication of MAC CE(s) with the UE.PATENT APPLICATION Attorney Docket No.: 0683-125-WO

[0170] In some embodiments, the first security parameter includes a base key (e.g., KBS). In some embodiments, the KBS is a K9NB ora KegNB. In some embodiments, the first security parameter includes security capabilities of the UE. The security capabilities indicate support of at least one security algorithm. In some embodiments, the CU derives the at least one first security key using at least one derivation function with the at least one security parameter. The CU may obtain at least one ID of the at least one security algorithm from the security capabilities and derives the at least one first security key using at least one derivation function, the base key, and / or the at least one ID. In such cases, the at least one first security parameter includes the at least one ID. In some embodiments, the CU may use one or more parameters to derive the at least one first security key. In some embodiments, the one or more parameters include a UE ID (e.g., a RNTI such as a cell RNTI). In other embodiments, the one or more parameters include a number or a counter.

[0171] In some embodiments, the at least one first security key includes a first integrity key, and the at least one security algorithm includes a first integrity algorithm. The CU derives the first integrity key using a first derivation function, the base key, and / or the ID of the first integrity algorithm. In some embodiments, the at least one first security key includes a first encryption key, and the at least one security algorithm includes a first encryption algorithm. The CU derives 806 the first encryption key using a second derivation function, the base key, and / or the ID of the first encryption protection algorithm.

[0172] Depending on embodiments, the at least one first security and the at least one second security parameter are the same, partially the same, or they are different. In some embodiments, the descriptions for the at least one security parameter in FIG. 7A may apply to the at least one second security parameter.

[0173] FIG. 8B is a flow diagram of an example method 800B similar to the method 800A, except that the method 800B includes block 820B instead of block 820A. At block 820B, the CU transmits a CU-to-DU message to the DU, including at least one first security key for secure communication of MAC CE(s) with the UE.

[0174] FIG. 8C is a flow diagram of an example method 800C similar to the method 800A, except that the method 800C includes blocks 852 and 820C instead of block 820A. At block 852, the CU derives at least one second security key from atPATENT APPLICATION Attorney Docket No.: 0683-125-WOleast one second security parameter and / or the at least one first security key. At block 820C, the CU transmits a CU-to-DU message to the DU, including at least one second security key for secure communication of MAC CE(s) with the UE. The description for the at least one second security parameter with respect to FIG. 3A can apply to the at least one second security parameter for FIG. 3C. In some embodiments, the at least one second security parameter is the same as the at least one first security parameter. In other embodiments, the at least one second security parameter is completely or partially different from the at least one second security parameter.

[0175] FIGs. 9A and 9B are flowcharts describing how one or more security algorithms are used by the DU for enabling the security protection of the MAC CE(s) with the UE, and FIGs. 10A and 10B are flowcharts describing how one or more security algorithms are used by the CU for enabling the security protection of the MAC CE(s), between the DU and the UE.

[0176] FIG. 9A illustrates an example method 900A, which may be performed by a DU (e.g., the DU 174). The method 900A begins at block 590, which was described with respect to FIG. 5A. At block 920A, the DU receives a CU-to-DU message from the CU, configuring at least one security algorithm for the secure communication of the MAC CE(s) with the UE. At block 929, the DU communicates the security-protected MAC CEs with the UE, using the at least one security algorithm. At block 733, the DU may optionally communicate non-security-protected MAC CEs with the UE (e.g., events 302, 304, 332, and / or 334). Block 733 may occur before, during, or after any block described above. In some embodiments, the at least one security algorithm includes an integrity algorithm and / or an encryption algorithm.

[0177] In some embodiments, the CU receives a CN-to-CU message from a CN (e.g., AMF), including security capabilities of the UE, where the security capabilities indicate support of the at least one security algorithm. In some embodiments, the security capabilities include one or more additional security algorithms. In some embodiments, the one or more additional security algorithms include one or more additional integrity algorithms and / or one or more additional encryption algorithms. The CU determines to use the at least security algorithm rather than the one or more additional security algorithms.PATENT APPLICATION Attorney Docket No.: 0683-125-WO

[0178] FIG. 9B is a flow diagram of an example method 900B similar to the method 900A, except that the method 900B includes block 960 instead of block 920A. At block 960, the DU receives a CU-to-DU message from the CU, including security capabilities of the UE, where the security capabilities indicate support of at least one security algorithm. In some embodiments, the CU-to-DU message is a UE Context Setup Request message ora UE Context Modification Request message. In some embodiments, the security capabilities include one or more additional security algorithms. In some embodiments, the one or more additional security algorithms include one or more additional integrity algorithms and / or one or more additional encryption algorithms. The DU determines to use the at least security algorithm rather than the one or more additional security algorithms. All other steps are similar to those discussed above with regard to FIG. 9A.

[0179] FIG. 10A illustrates an example method 1000A, which may be performed by a CU (e.g., the CU 172). The method 1000A begins with block 1060A where the CU receives security capabilities of a UE, indicating support of at least one first security algorithm and at least one second security algorithm. At block 1006, the CU transmits a CU-to-UE message to a UE, via a DU, configuring the at least one first security algorithm for data (excluding MAC CE) communication with the UE. At block 1020A, the CU transmits 1020A a CU-to-DU message to the DU, configuring the at least one second security algorithm for the DU to perform secure communication for MAC CE(s) with the UE. At block 1094, the CU communicates security-protected data (excluding the MAC CE) with the UE via the DU, using the at least one first security algorithm.

[0180] In some embodiments, the at least one first security algorithm includes at least one of a first integrity algorithm and a first encryption algorithm. In some embodiments, the at least one second security algorithm includes at least one of a second integrity algorithm and a second encryption algorithm. In some embodiments, the at least one first security algorithm and the at least one second security algorithm are completely or partially different. Thus, in this method, different security algorithms are used by the UE to apply security protection to the data (excluding the MAC CE) and to the MAC CE(s).

[0181] FIG. 10B is a flow diagram of an example method 1000B similar to the method 1000A, except that the method 1000B includes blocks 1060B and 1020BPATENT APPLICATION Attorney Docket No.: 0683-125-WOinstead of blocks 1060A and 1020A. At block 1060B, the Gil receives security capabilities of a UE indicating support of at least one first security algorithm. At block 1020B, the CU transmits a CU-to-DU message to the DU, configuring the at least one first security algorithm for the DU to perform secure communication for MAC CE(s) with the UE. Thus, in this method, the same security algorithm is used by the UE to apply security protection to the data (excluding the MAC CE) and to the MAC CE(s).

[0182] FIG. 11 illustrates an example method 1100, which may be performed by a DU (e.g., the DU 174) in case that an integrity check of the MAC CE fails. The method 1100A begins at block 590, as described with respect to FIG. 5A. At block 1122, the DU activates the security protection for communicating the MAC CE(s) with the UE. At block 1130, the DU receives an integrity-protected MAC CE from the UE and, at block 1162, the DU performs an integrity check to verify the integrity of the received MAC CE. At block 1164, the DU determines an integrity check failure as a result of the integrity check (i.e., the MAC CE fails the integrity check). When this happens, the method 1100 may proceed to block 1166 or block 1168. In response to the integrity check failure, at block 1166, the DU may transmit a DU-to-CU message to the CU, indicating a failure of the integrity check, or at block 1168, the DU may transmit a DU-to-CU message to the CU, causing the CU to transition the UE to an idle state. The method 1100 may proceed with block 1172 where the DU receives a CU-to-DU message from the CU, commanding the DU to release a UE context of the UE.

[0183] FIG. 12 illustrates an example method 1200, which may be performed by a CU (e.g., the CU 174) in case that an integrity check of the MAC CE fails. The method 1200 begins with block 1290 where the CU communicates with a UE and a DU. At bock 1220, the CU may transmit a CU-to-DU message to the DU, causing the UE to activate the security protection for communicating MAC CE(s) with the DU. The method 1200 proceeds to block 1266 or block 1268. At block 1266, the CU receives a DU-to-CU message from the DU, indicating a failure of the integrity check. Alternatively, at block 1268, the CU receives a DU-to-CU message from the DU, causing the CU to transition the UE to an idle state. The method 1200 proceeds with block 1270, where the CU transmits a message to the UE, via the DU, to release a connection between the UE and the CU. In some embodiments, the message is anPATENT APPLICATION Attorney Docket No.: 0683-125-WORRC release message. At block 1272, the CU may transmit a CU-to-DU message to the DU, commanding the DU to release a UE context of the UE.

[0184] FIG. 13 is a flowchart of a method 1300 for wireless communication performed by a DU (e.g., DU 174) of a RAN node (e.g., BS 104) for activating a security protection for communicating MAC CE(s). One or more steps in this method are associated with the steps illustrated in FIGs. 3A to 4C. The method 1300 begins with block 1380 where the DU transmits to the UE (e.g., UE 102) a command associated with a first secure algorithm for security protection of the MAC CE. At block 1328, the DU communicates, with the UE, a security protected MAC CE based on the first secure algorithm. At block 1390, the DU may optionally establish communication with the UE and CU, for transmitting data excluding the MAC CE. In one embodiment, the communication may also include exchanging non-security protected MAC CE(s). After blocks 1380 and 1328, the DU and UE may communicate non-security protected MAC CE(s) at block 1332, in addition to the security protected MAC CE(s).

[0185] The method 1300 may further include determining, at the DU, to activate the security protection of the MAC CE. In one embodiment, the command is a security activation command. The method may further include transmitting, to the CU associated with the RAN node, a DU-to-CU message for requesting to activate the security protection for communicating the security protected MAC CE with the UE, and receiving, from the CU, a CU-to-DU message for confirming to activate the security protection for communicating the security protected MAC CE with the UE, where the command is a CU-to-UE message.

[0186] In another embodiment, the method 1300 may include transmitting, to the CU associated with the RAN node, a DU-to-CU message including a configuration to activate the security protection for communicating the security protected MAC CE with the UE, where the command is a CU-to-UE message.

[0187] In yet another embodiment, the method 1300 may include transmitting, to the CU associated with the RAN node, a security mode command message that indicates a second secure algorithm for security protection of data, the data excluding the MAC CE. Alternatively, the method 1300 may include receiving, from the CU associated with the RAN node, a CU-to-DU message for activating the security protection of the MAC CE, where the command is a security modePATENT APPLICATION Attorney Docket No.: 0683-125-WOcommand message. The first secure algorithm is different from the second secure algorithm, the first secure algorithm is applied at a MAC layer and the second secure algorithm is applied at a layer higher than the MAC layer. However, the first secure algorithm may be the same as the second secure algorithm.

[0188] For the above embodiments, the first secure algorithm includes at least one of an integrity algorithm ora ciphering algorithm. The integrity algorithm includes an input based on at least one of: a logical channel identifier, LCID, associated with the MAC CE, a UE identifier associated with the UE, a parameter associated with a layer higher than a MAC layer, or the MAC CE. The ciphering algorithm includes an input based on at least one of: the LCID associated with the MAC CE, a UE identifier associated with the UE, or a parameter associated with a layer higher than a MAC layer.

[0189] The method 1300 may further include receiving, from the CU associated with the RAN node, at least one of a security parameter or a security key to be used for the security protection. When the communicating step includes receiving, from the UE, the security protected MAC CE, the method may further include determining that an integrity check performed on the security protected MAC CE has failed, and transmitting, to the CU associated with the RAN node, a DU-to-CU message including an indication that the integrity check has failed. In one embodiment, when the communicating step includes receiving, from the UE, the security protected MAC CE, the method further includes determining that an integrity check performed on the security protected MAC CE has failed, and transmitting, to the CU, a DU-to-CU message to cause the CU to transition the UE to an idle state. In one embodiment, the method may further include receiving a CU-to-DU message requesting the DU to release a UE context of the UE.

[0190] The step of communicating may further include applying the first secure algorithm based on a type of the MAC CE. The type includes at least one of: a MAC CE associated with beam management or radio resource management; a MAC CE that activates or deactivates radio resources associated with at least one of: one or more reference signals, a primary secondary cell, PSCell, or one or more secondary cells, SCells; a MAC CE associated with a lower layer triggered mobility (LTM) command that activates or deactivates layer 1 or layer 2 measurement configuration or reporting; a MAC CE that activates or deactivates one or more sounding referencePATENT APPLICATION Attorney Docket No.: 0683-125-WOsignals, SRSs; a MAC CE that is a discontinuous reception (DRX) command or a long DRX command; a MAC CE that activates, deactivates, or indicates a transmission configuration indication (TCI); a MAC CE associated with at least one of a pathloss reference, spatial relation for a resource set, a physical channel, or a bit rate; a MAC CE that includes a UE identifier, ID, ora UE contention resolution ID; a MAC CE that activates or deactivates a measurement gap; a MAC CE that configures or updates an uplink transmission timing or a downlink reception timing; or a MAC CE associated with a timing advance command.

[0191] The method 1300 may further include communicating, with the UE, data in a MAC protocol data unit, PDU. In one embodiment, the security protected MAC CE is multiplexed with the data in the MAC PDU. In another embodiment, the security protected MAC CE is multiplexed with the data and non-security protected MAC CE in the MAC PDU. In yet another embodiment, the security protected MAC CE is multiplexed with the data in the MAC PDU and with a message authentication code for integrity, MAC-I, associated with the first secure algorithm.

[0192] The step of communicating includes at least one of transmitting, to the UE, the security protected MAC CE, or receiving, from the UE, the security protected MAC CE.

[0193] FIG. 14 is a flowchart of a method 1400 for wireless communication performed by a CU (e.g., CU 172), of a RAN node (e.g., BS 104). At block 1420, the method includes the CU transmitting, to or via a DU (e.g., DU 174) associated with the RAN node, a message associated with a first secure algorithm for security protection of a MAC CE, and at block 1494, the CU communicating, with the UE, via the DU, security protected data excluding the MAC CE. At block 1418, the method 1400 may include the CU determining to activate the security protection of the MAC CE. At block 1408, the method 1400 may also include the CU transmitting, to the UE, via the DU, a command associated with a second secure algorithm for security protection of the data excluding the MAC CE. In one embodiment, the method 1400 also includes transmitting, to the DU, a CU-to-DU message for activating the security protection at the DU for communicating the security protected MAC CE with the UE, and / or transmitting, to the UE via the DU, a CU-to-UE message for activating the security protection at the UE for communicating the security protected MAC CE.PATENT APPLICATION Attorney Docket No.: 0683-125-WO

[0194] In one embodiment, the message may include a first message for the DU to activate the security protection for the MAC CE, and a second message for the UE to activate the security protection for the MAC CE. In another embodiment, the message includes a configuration for activating the security protection for the MAC CE. The method 1400 may further include transmitting the message to the UE when the UE supports security protection for the MAC CE.

[0195] In one embodiment, the method 1400 may include receiving, from a CN, a CN-to-CU message including a first security parameter for the UE, deriving a first security key for the UE, based on the first security parameter, communicating, with the UE via the DU, a security protected data based on the first security key, and transmitting, to the DU, a CU-to-DU message including at least one of: the first security key, the first security parameter, a second security parameter, or a second security key to be used for the security protection of the MAC CE.

[0196] In this or another embodiment, the method 1400 may include receiving, from the DU, a DU-to-CU message indicating a failure of an integrity check for the security protected MAC CE from the UE, or causing the CU to transition the UE to an idle state, and transmitting, to the UE via the DU, a message to release a connection with the CU. For any of the embodiments of the method 1400, the first secure algorithm is different from the second secure algorithm, the first secure algorithm is applied at a MAC layer and the second secure algorithm is applied at a layer higher than the MAC layer. In one variation, the first secure algorithm is the same as the second secure algorithm.

[0197] In one embodiment, the first secure algorithm includes at least one of an integrity algorithm ora ciphering algorithm. The integrity algorithm includes an input based on at least one of: an LCID associated with the MAC CE, a UE identifier associated with the UE, a parameter associated with a layer higher than a MAC layer, or the MAC CE. The ciphering algorithm includes an input based on at least one of: an LCID associated with the MAC CE, a UE identifier associated with the UE, or a parameter associated with a layer higher than a MAC layer.

[0198] FIG. 15 is a flowchart of a method 1500 for wireless communication performed by a UE (e.g., the UE 102) for applying security protection to MAC CE(s), in addition of the security protection applied to the data that excludes MAC CE(s). At block 1580, the method 1500 includes the UE receiving 1580, from or via a DU (e.g.,PATENT APPLICATION Attorney Docket No.: 0683-125-WOthe DU 174) of a RAN node (e.g., BS 104), a message associated with a first secure algorithm for security protection of a MAC CE, and at block 1528, the UE communicating, with the DU, a security protected MAC CE based on the first secure algorithm. At block 1510, the method 1500 may further include the UE receiving, from the CU via the DU, a command associated with a second secure algorithm for security protection of data excluding the MAC CE. In one embodiment, the method 1500 also includes communicating, with the CU via the DU, a security protected data based on the second secure algorithm.

[0199] The first and second secure algorithms are different, the first secure algorithm is applied at a MAC layer, and the second secure algorithm is applied at a layer higher than the MAC layer. In one embodiment, the first secure algorithm is the same as the second secure algorithm. The first secure algorithm includes at least one of an integrity algorithm ora ciphering algorithm. The integrity algorithm includes an input based on at least one of: an LCID associated with the MAC CE, a UE identifier associated with the UE, a parameter associated with a layer higher than a MAC layer, or the MAC CE. The ciphering algorithm includes an input based on at least one of: an LCID associated with the MAC CE, a UE identifier associated with the UE, or a parameter associated with a layer higher than a MAC layer.

[0200] The method 1500 may further include receiving at least one of a security parameter or a security key to be used for the security protection. In one embodiment, the communicating includes applying the first secure algorithm based on a type of the MAC CE. The type includes: a MAC CE associated with beam management or radio resource management; a MAC CE that activates or deactivates radio resources associated with at least one of: one or more reference signals, a primary secondary cell, PSCell, or one or more secondary cells, SCells; a MAC CE associated with a lower layer triggered mobility (LTM) command that activates or deactivates layer 1 or layer 2 measurement configuration or reporting; a MAC CE that activates or deactivates one or more sounding reference signals, SRSs; a MAC CE associated with a discontinuous reception, DRX, command ora long DRX command; a MAC CE that activates, deactivates, or indicates a transmission configuration indication, TCI; a MAC CE associated with at least one of a pathloss reference, spatial relation for a resource set or a physical channel, or a bit rate; a MAC CE that includes a UE identifier, ID, or a UE contention resolution ID; aPATENT APPLICATION Attorney Docket No.: 0683-125-WOMAC CE that activates or deactivates a measurement gap; a MAC CE that configures or updates an uplink transmission timing or a downlink reception timing; or a MAC CE associated with a timing advance command.

[0201] The method 1500 may further include communicating, with the CU via the DU, data excluding the MAC CE, where the data is included in a MAC protocol data unit, PDU. In one embodiment, the security protected MAC CE may be multiplexed with the data in the MAC PDU. In another embodiment, the security protected MAC CE is multiplexed with the data and a non-security protected MAC CE in the MAC PDU. In yet another embodiment, the security protected MAC CE is multiplexed with the data in the MAC PDU and with a message authentication code for integrity, MAC-I, associated with the first secure algorithm.

[0202] A communication device 102, 104 that includes a processor 132 or 142 and a transceiver 134 or 144, respectively, is configured to cooperatively execute the methods discussed in this document.

[0203] FIGs. 16A and 16B illustrate the application of an integrity algorithm to data and MAC CE(s), respectively, FIGs. 17A and 17B illustrate the application of an encoding algorithm to data and MAC CE(s), respectively, and FIGs. 18A to 18D illustrate the multiplexing of data excluding MAC CE(s), security protected MAC CE(s), and one or more other parameters.

[0204] FIG. 16A illustrates various inputs applied to an integrity algorithm for generating the MAC-I discussed above, for integrity protection and integrity check of the data excluding the MAC CE. A sender 1601 and a receiver 1611, which each may be a UE (e.g., the UE 102) or a network entity (e.g., BS 104, CU 172, DU 174) use the same integrity algorithm to generate a Z-bit MAC-I and XMAC-I (here X stands for “expected”), respectively, based on a Ki-bit integrity KEY, an L-bit COUNT, an M-bit BEARER identity, a 1 -bit DIRECTION of the transmission (which is 0 for uplink and 1 for downlink), and the MESSAGE itself. In some embodiments, the MESSAGE is a message (one of the messages discussed with regard to FIGs. 3A to 4C), a UL data packet, or a DL data packet as described above. In other embodiments, the MESSAGE is an UL PDU including a UL message, an UL PDU including an UL data packet, a DL PDU including a DL message, ora DL PDU including a DL data packet as described above. In some embodiments, the UL PDUs and DL PDUs are PDCP PDUs. In some embodiments, Ki is 128, 256, or 512. InPATENT APPLICATION Attorney Docket No.: 0683-125-WOsome embodiments, L is 32, 64, 128, 256, or 512. In some embodiments, M is 5 or 6. In some embodiments, the integrity algorithm is a null algorithm (e.g., NIAO or 6GIA0), which does not provide integrity protection. In some embodiments, the integrity algorithm is a Ki-bit SNOW 3G based algorithm, a Ki -bit AES based algorithm, a Ki-bitZUC based algorithm, ora Ki-bit SHA based algorithm. The sender 1601 appends the MAC-I to the MESSAGE. The receiver 1611 verifies the integrity of the received data by comparing the XMAC-I with the MAC-I appended to the MESSAGE.

[0205] FIG. 16B illustrates various inputs applied to an integrity algorithm for integrity protection and integrity check of MAC CEs. The sender 1601 and the receiver 1611 (the same as in FIG. 16A) use the same integrity algorithm to generate a Y-bit MAC-I and XMAC-I (here X stands for “expected”), respectively, based on a K2-bit integrity KEY, an N-bit logical channel identity (LCID), a 1 -bit DIRECTION of the transmission, a UE ID, and / or a higher layer (the higher layer refers to any layer higher than the MAC layer) parameter, and the MESSAGE itself. In some embodiments, the UE ID is a RNTI (e.g., cell RNTI). In some embodiments, the MESSAGE is a MAC CE as described above. In other embodiments, the MESSAGE is a MAC subPDU, including a MAC CE subheader and a MAC CE, as described above. In other embodiments, the MESSAGE is a plurality of MAC subPDUs, each including a MAC CE subheader and a MAC CE, as described above. In some embodiments, K2 < Ki. For example, K2 is 32, 64, 128, 256, or 512. In some embodiments, N is < 16. For example, N is 5, 6, 7, 8, or 16. In some implementations, the UE ID has P bits. For example, P < 32. In another example, P is 16, 24, or 32. In some embodiments, the integrity algorithm is a null algorithm (e.g., NIAO or6GIA0), which does not provide integrity protection. In some embodiments, the integrity algorithm is a K2-bit SNOW 3G based algorithm, a K2-bit AES based algorithm, a K2-bit ZUC based algorithm, or a K2-bit SHA based algorithm. The sender 1601 appends the MAC-I to the MESSAGE. The receiver 1611 verifies its integrity by comparing the XMAC-I with the MAC-I appended to the MESSAGE.

[0206] FIG. 17A illustrates various inputs applied to a ciphering algorithm for encrypting and decrypting data excluding the MAC CE. Both a sender 1701 and a receiver 1711 (which may be the sender 1601 and the receiver 1611) use aPATENT APPLICATION Attorney Docket No.: 0683-125-WOciphering algorithm to generate an output KEYSTREAM block using as input a Ks-bit cipher KEY, a L-bit COUNT, a M-bit BEARER identity, the 1 -bit DIRECTION of the transmission, and the LENGTH of the keystream (e.g., a PLAINTEXT block) as input parameters. In one embodiment, a keystream block is a sequence of pseudorandom or random characters. The sender 1701 then uses the KEYSTREAM block to encrypt 1703 the PLAINTEXT block thereby generating the output CIPHERTEXT block. In some embodiments, the PLAINTEXT is a message, an UL data packet, or a DL data packet as described above. In other embodiments, the PLAINTEXT includes a message and a MAC-I for the message, a UL data packet and a MAC-I for the UL data packet, or a DL data packet and a MAC-I for the DL data packet, as described for Fig. 3A or Fig. 3B. In other embodiments, the PLAINTEXT includes a message and a MAC-I for the message, a UL data packet and a MAC-I for the UL data packet, or a DL data packet and a MAC-I for the DL data packet, as described for FIG. 16A or FIG. 16B. In some embodiments, Ka is 128, 256, or 512. L and M are as described for FIG. 16A. The receiver 1711 uses the KEYSTREAM block, which it generates in the same manner as the sender 1701, to decrypt 1705 the CIPHERTEXT block thereby regenerating the output PLAINTEXT block. The sender 1701 and the receiver 1711 use the same ciphering algorithm. In some embodiment, the ciphering algorithm is a null ciphering algorithm (e.g., NEA0 or6GEA0), which provides no encryption. In some embodiments, the ciphering algorithm is a Ks-bit SNOW 3G based algorithm, a Ks-bit AES based algorithm, a 128-bit ZUC based algorithm Ks-bit, or a Ks-bit SHA based algorithm.

[0207] FIG. 17B illustrates various inputs applied to a ciphering algorithm for encrypting and decrypting MAC CEs. Both the sender 1701 and receiver 1711 use a ciphering algorithm to generate an output KEYSTREAM block using a K4-bit cipher KEY, an N-bit logical channel identity (LCID), the 1 -bit DIRECTION of the transmission, the LENGTH of the keystream (e.g., the PLAINTEXT block), a UE ID, and / or a higher layer parameter as input parameters. In some embodiments, the UE ID is a RNTI (e.g., cell RNTI). The sender 1701 then uses the KEYSTREAM block to encrypt 1703 the PLAINTEXT block thereby generating the output CIPHERTEXT block. In some embodiments, the PLAINTEXT is a UL MAC CE or a DL MAC CE as described above. In some embodiments, the PLAINTEXT block includes a MAC CE and a MAC-I for the MAC-I as described for FIG. 16A or FIG. 16B. In otherPATENT APPLICATION Attorney Docket No.: 0683-125-WOembodiments, the PLAINTEXT block is a plurality of MAC subPDUs, each including a MAC CE subheader and a MAC CE, as described for FIG. 16A or FIG. 16B. In some embodiments, K4 is 32, 64, 128, 256, or 512. N is as described for FIG. 16B. The receiver 1711 uses the KEYSTREAM block, which it generates in the same manner as the sender, to decrypt 1705 the Cl PHERTEXT block thereby regenerating the output PLAINTEXT block. The sender 1701 and the receiver 1711 use the same ciphering algorithm. In some embodiment, the ciphering algorithm is a null ciphering algorithm (e.g., NEAO or6GEA0), which provides no encryption. In some embodiments, the ciphering algorithm is a K4-bit SNOW 3G based algorithm, a Ks-bit AES based algorithm, a 128-bit ZUC based algorithm K4-bit, or a K4-bit SHA based algorithm.

[0208] FIG. 18A illustrates a MAC PDU 1802 having one or more MAC subPDUs. Some of the MAC subPDUs 1804 include a corresponding MAC CE while others 1810 include MAC SDU. Each MAC subPDU 1804 has a corresponding security protected MAC CE 1806 and a corresponding MAC CE subheader 1808. Each MAC subPDU 1810 includes MAC SDU 1812 and a corresponding MAC SDU subheader 1814.

[0209] FIG. 18B illustrates a MAC PDU 1820 having MAC subPDUs 1804 (same structure as in FIG. 18A), MAC subPDUs 1810 (same structure as in FIG. 18A) and MAC subPDUs 1824. The MAC subPDU 1824 includes a non-security protected MAC CE1826 and a corresponding MAC CE subheader 1828. The non-security-protected MAC CEs and security-protected MAC CEs in the MAC PDU 1820 may be multiplexed.

[0210] FIG. 18C shows a MAC PDU 1830 that includes at least one of a MAC subPDU 1832 for security protection, a MAC subPDU 1838 including a MAC CE, and a MAC subPDU 1810. The MAC subPDU 1832 includes the MAC-I 1834 (previously discussed with regard to FIGs 16A and 16B), and a corresponding MAC CE subheader 1836. The MAC subPDU 1838 includes a MAC CE 1840 and a corresponding header MAC CE subheader 1842. In this embodiment, although various MAC subPDU 1832, 1838, and 1810 are present in the MAC PDU 1830, they are multiplexed according to a given order, for example, security protection related MAC CEs, non-security protection related MAC CEs, and MAC SDUs.Differently, FIG. 18D multiplexes the MAC subPDU with a different order, e.g., MAC-IPATENT APPLICATION Attorney Docket No.: 0683-125-WOand corresponding MAC CE subheader is placed after the MAC CEs and before the MAC SDU.

[0211] The format of the MAC PDU 1802, 1820, 1830, and / or 1840 may be applicable to the MAC PDlls described for FIGs. 16A and 16B. The descriptions for security-protected MAC CEs described for FIGs. 16A and 16B may apply the security-protected MAC CEs in Figs. 6A-6D. The descriptions for security-protected data packets or messages described for FIGs. 16A and 16B may apply the security-protected data in FIGs. 18A to 18D. If there is neither data packet nor message to transmit, the MAC subPDUs including MAC SDlls in the MAC PDU 1802, 1820, 1830, and 1840 may be omitted. Generally, the MAC PDU 1802, 1820, 1830, and 1840 may include any number of MAC subPDU, where each MAC subPDU includes a MAC CE subheader and a MAC CE

[0212] For all the above embodiments, the descriptions and scenarios described in one figure may apply to any other figure, if applicable. In the same spirit, examples, embodiments, and methods described above may be combined, if there is no conflict. An event or block described above may be optional or omitted. For example, an event or block with dashed lines in the figures may be optional. The description from the perspective of a receiving node or a receiving network entity or a component of the receiving node also applies to the sending node or the sending network entity or a component of sending node. For example, a description that a receiving node (e.g., DU) receives a message from a sending node (e.g., CU) may be replaced by the sending node sending a message to the receiving node.Similarly, a description that a receiving node (e.g., CU) receives a message from a sending node (e.g., DU) may be replaced by the sending node sending a message to the receiving node.

[0213] In some embodiments, the term “message” is used and may be replaced by “information element (IE)”, and vice versa. In some embodiments, “IE” is used and may be replaced by “field”, and vice versa. In some embodiments, the term “configuration” may be replaced by “configurations” or “configuration parameters”, and vice versa. In some embodiments, the term “activate” may be replaced by “enable” or “configure”, and vice versa. In some embodiments, the term “deactivate” may be replaced by “disable” or “release”, and vice versa. In some embodiments, the term “applied to” may be replaced by “configured for” or “activated for”, and vicePATENT APPLICATION Attorney Docket No.: 0683-125-WOversa. In some embodiments, the term “distributed” may be replaced by “disaggregated”. In some embodiments, the term “secure” may be replaced by “security”, and vice versa.

[0214] A user device in which the techniques of this disclosure may be performed (e.g., the UE 102) may be any suitable device capable of wireless communications such as a smartphone, a tablet computer, a laptop computer, a mobile gaming console, a point-of-sale (POS) terminal, a health monitoring device, a drone, a camera, a media-streaming dongle or another personal media device, a wearable device such as a smartwatch, a wireless hotspot, a femtocell, or a broadband router. Further, the user device in some cases may be embedded in an electronic system such as the head unit of a vehicle or an advanced driver assistance system (ADAS). Still further, the user device may operate as an internet-of-things (loT) device or a mobile-internet device (MID). Depending on the type, the user device may include one or more general-purpose processors, a computer-readable memory, a user interface, one or more network interfaces, one or more sensors, etc.

[0215] Certain embodiments are described in this disclosure as including logic or a number of components or modules. Modules may be software modules (e.g., code, or machine-readable instructions stored on non-transitory machine-readable medium) or hardware modules. A hardware module is a tangible unit capable of performing certain operations and may be configured or arranged in a certain manner. A hardware module may include dedicated circuitry or logic that is permanently configured (e.g., as a special-purpose processor, such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC), a digital signal processor (DSP), etc.) to perform certain operations. A hardware module may also include programmable logic or circuitry (e.g., as encompassed within a general-purpose processor or other programmable processor) that is temporarily configured by software to perform certain operations. The decision to implement a hardware module in dedicated and permanently configured circuitry, or in temporarily configured circuitry (e.g., configured by software) may be driven by cost and time considerations.

[0216] When implemented in software, the techniques may be provided as part of the operating system, a library used by multiple applications, a particular softwarePATENT APPLICATION Attorney Docket No.: 0683-125-WOapplication, etc. The software may be executed by one or more general-purpose processors or one or more special-purpose processors.

[0217] Upon reading this document, those of skill in the art will appreciate still additional and alternative structural and functional designs for handling mobility between BSs or their components, through the principles disclosed herein. Thus, while particular embodiments and applications have been illustrated and described, it is to be understood that the disclosed embodiments are not limited to the precise construction and components disclosed herein. Various modifications, changes and variations, which will be apparent to those of ordinary skill in the art, may be made in the arrangement, operation and details of the method and apparatus disclosed herein without departing from the spirit and scope defined in the appended claims.

Claims

PATENT APPLICATION Attorney Docket No.: 0683-125-WOWhat is claimed is:

1. A method (1300) for wireless communication performed by a distributed unit, DU, (174) of a radio access network, RAN, node (104), the method comprising:transmitting (1380), to a user equipment, UE, (102) a command associated with a first secure algorithm for a security protection of a medium access control, MAC, control element, CE; andcommunicating (1328), with the UE, a security protected MAC CE generated based on the first secure algorithm.

2. The method of Claim 1, further comprising:determining to activate the security protection of the MAC CE, wherein the command is a security activation command.

3. The method of Claim 2, further comprising:transmitting, to a central unit, CU, associated with the RAN node, a DU-to-CU message for requesting the CU to activate the security protection or including a configuration to activate the security protection; andreceiving, from the CU, a CU-to-DU message for confirming to activate the security protection, wherein the command is a CU-to-UE message.

4. The method of Claim 1, further comprising:transmitting, to the UE, a security mode command message that indicates a second secure algorithm for security protection of data excluding the MAC CE; or receiving, from a central unit, CU, a CU-to-DU message for activating the security protection of the MAC CE, wherein the command is a security mode command message.

5. The method of Claim 4, wherein the first secure algorithm is applied at a MAC layer and the second secure algorithm is applied at a layer higher than the MAC layer.PATENT APPLICATION Attorney Docket No.: 0683-125-WO6. The method of Claim 1 , wherein the first secure algorithm includes at least one of an integrity algorithm ora ciphering algorithm.

7. The method of Claim 6, wherein the integrity algorithm or ciphering algorithm includes an input based on at least one of:a logical channel identifier, LCID, associated with the MAC CE;a UE identifier associated with the UE;a parameter associated with a layer higher than a MAC layer;or the MAC CE payload.

8. The method of Claim 1, further comprising:receiving, from a central unit, CU, at least one of a security parameter or a security key to be used for the security protection.

9. The method of Claim 1 , wherein the communicating the security protected MAC CE comprises:performing an integrity check on a security protected MAC CE received from the UE; andtransmitting, to a central unit, CU, a DU-to-CU message indicating an integrity check failure or causing the CU to transition the UE to an idle state.

10. The method of Claim 1, wherein the communicating comprises: selectively applying the first secure algorithm based on a type of the MAC CE, the type including at least one of: beam management, radio resource management, LTM cell switch commands, TCI state indications, or timing advance commands.

11. A method (1400) for wireless communication performed by a central unit, CU, (172), of a radio access network, RAN, node (104), the method comprising: transmitting (1420), to or via a distributed unit, DU, (174) associated with the RAN node, a message associated with a first secure algorithm for security protection of a medium access control, MAC, control element, CE; andcommunicating (1494), with a user equipment, UE, via the DU, security protected data excluding the MAC CE.PATENT APPLICATION Attorney Docket No.: 0683-125-WO12. The method of Claim 11, further comprising:transmitting, to the UE via the DU, a command associated with a second secure algorithm for security protection of data excluding the MAC CE; and transmitting, to the DU, a CU-to-DU message for activating the security protection for communicating the security protected MAC CE with the UE.

13. The method of Claim 11 , wherein the message includes at least one of: a first message for the DU to activate security protection,a second message for the UE to activate security protection, ora configuration for activating security protection for the MAC CE.

14. The method of Claim 11, further comprising:receiving, from a core network, CN, a message including a first security parameter;deriving a first security key based on the first security parameter; and transmitting, to the DU, a CU-to-DU message including at least one of the first security key, the first security parameter, or a second security key derived for the MAC CE.

15. The method of Claim 11 , further comprising:receiving, from the DU, a DU-to-CU message indicating an integrity check failure for the security protected MAC CE; andtransmitting a message to release a connection with the UE.

16. A method (1500) for wireless communication performed by a user equipment, UE, (102), the method comprising:receiving (1580), from or via a distributed unit, DU, (174) of a radio access network, RAN, node (104), a message associated with a first secure algorithm for security protection of a medium access control, MAC, control element, CE; and communicating (1528), with the DU, a security protected MAC CE based on the first secure algorithm.PATENT APPLICATION Attorney Docket No.: 0683-125-WO17. The method of Claim 16, further comprising:receiving a command associated with a second secure algorithm for security protection of data excluding the MAC CE; andcommunicating security protected data based on the second secure algorithm, wherein the first secure algorithm is applied at a MAC layer and the second secure algorithm is applied at a layer higher than the MAC layer.

18. The method of Claim 16, wherein the first secure algorithm includes an integrity or ciphering algorithm utilizing an input based on at least one of:a logical channel identifier, LCID,a UE identifier,a parameter associated with a layer higher than a MAC layer, orthe MAC CE.

19. The method of Claim 16, wherein the communicating comprises: applying the first secure algorithm selectively based on a type of the MAC CE; andmultiplexing the security protected MAC CE with data and non-security protected MAC CEs in a single MAC PDU.

20. A communication device (102, 104) comprising a processor and a transceiver configured to cooperatively execute the methods of claims 1 to 19.

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