Method, device and system for SCG security in wireless networks

Abstract

The present disclosure generally relates to a method, device, and system for ensuring security related to an SCG in a wireless network. One method implemented by a wireless device is disclosed. The method may include selecting a target PS cell, determining whether an SN counter associated with the target SN needs to be updated, determining that the SN counter associated with the target SN needs to be updated, selecting a refreshed SN counter value, and updating at least the SN counter associated with the target SN with the refreshed SN counter value, and transmitting a first message to a master node requesting a switch from a current PS cell to the target PS cell.

Description

[Technical Field]

[0001] The present disclosure is directed generally to wireless communications, and specifically to methods, devices, and systems for ensuring security associated with secondary carrier groups (SCGs) and / or secondary nodes (SNs) in a wireless network. [Background technology]

[0002] With the rapid evolution of wireless communication technology, to meet the demands for higher speeds, higher throughput and capacity, higher efficiency, and lower latency, dual connectivity is introduced, in which two base stations are employed to support a master carrier group (MCG) and an SCG. Switching between SCGs and adding new SCGs, as well as switching between cells within the same SCG, are supported to achieve robust secondary connectivity. Minimizing the execution time for these procedures and improving performance are important. Summary of the Invention [Means for solving the problem]

[0003] The present disclosure is directed to methods, devices, and systems for ensuring security associated with an SCG and / or an SN in a wireless network.

[0004] In some embodiments, a method implemented by a wireless device is disclosed. The method may include, in response to an execution condition being satisfied, selecting a target primary secondary cell (PScell) in a radio access network (RAN), the target PScell being associated with a target secondary node (SN), the target SN being a member of a list of SNs, each SN in the list of SNs being associated with an SN counter, the SN counter being used to calculate a security key for each SN in the list of SNs; determining whether an SN counter associated with the target SN needs to be updated; determining that the SN counter associated with the target SN needs to be updated, selecting a refreshed SN counter value, and updating at least the SN counter associated with the target SN with the refreshed SN counter value, the refreshed SN counter value being different from any previous SN counter value shared between the wireless device and a master node; and transmitting a first message to the master node requesting a switch from a current PScell to the target PScell, the first message including the refreshed SN counter value.

[0005] In some embodiments, a method implemented by a master network node in a radio access network (RAN) is disclosed. The method may include receiving a first message from a wireless device requesting to switch the wireless device from a current PS cell to a target PS cell, the first message including a refreshed SN counter value for updating an SN counter, the refreshed SN counter value indicating that a target SN associated with the target PS cell is different from an SN associated with the current PS cell.

[0006] In some embodiments, there is a wireless device, network element, or network node comprising a processor and a memory, wherein the processor is configured to read code from the memory and to perform any method recited in any of the embodiments.

[0007] In some embodiments, a computer program product comprises computer readable medium code stored thereon which, when executed by a processor, causes the processor to implement any method recited in any of the embodiments.

[0008] The above embodiments, and other aspects and alternatives of their implementations, are described in more detail in the following drawings, description, and claims. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 illustrates an exemplary wireless communication network.

[0010] [Figure 2] FIG. 2 illustrates an exemplary wireless network node.

[0011] [Figure 3] FIG. 3 shows an exemplary user equipment.

[0012] [Figure 4] FIG. 4 shows an exemplary dual connectivity configuration with a gNB acting as a master node (MN) and an eNB acting as a secondary node (SN).

[0013] [Figure 5] FIG. 5 illustrates an exemplary SN addition / modification procedure initiated by the MN.

[0014] [Figure 6]FIG. 6 illustrates an exemplary SN configuration that is pre-configured in the UE.

[0015] [Figure 7] FIG. 7 illustrates an exemplary conditional PScell change (CPC) or conditional PScell addition (CPA) procedure initiated by a UE that is pre-configured with candidate SCGs (or candidate SNs).

[0016] [Figure 8] FIG. 8 shows a candidate SN pool with three candidate SNs and candidate cells within each candidate SN. DETAILED DESCRIPTION OF THE INVENTION

[0017] Detailed Description wireless communication network FIG. 1 shows an exemplary wireless communication network 100 including a core network 110 and a radio access network (RAN) 120. The core network 110 further includes at least one mobility management entity (MME) 112 and / or at least one access and mobility management function (AMF). Other functions that may be included in the core network 110 are not shown in FIG. 1. The RAN 120 further includes multiple base stations, e.g., base stations 122 and 124. The base stations may include at least one evolved NodeB (eNB) for 4G LTE, an enhanced LTE eNB (ng-eNB), or a next-generation NodeB (gNB) for 5G new radio (NR), or any other type of signal transmission / reception device, such as a UMTS NodeB. The eNB 122 communicates with the MME 112 via an S1 interface. Both the eNB 122 and the gNB 124 may connect to the AMF 114 via an Ng interface. Each base station manages and supports at least one cell. For example, base station gNB124 may be configured to manage and support cell 1, cell 2, and cell 3.

[0018] The gNB 124 may include a central unit (CU) and at least one distributed unit (DU). The CU and DU may be co-located in the same location, or they may be separated into different locations. The CU and DU may be connected via an F1 interface. Alternatively, with respect to an eNB capable of connecting to a 5G network, this may also be similarly separated into a CU and at least one DU, referred to as an ng-eNB-CU and an ng-eNB-DU, respectively. The ng-eNB-CU and ng-eNB-DU may be connected via a W1 interface.

[0019] The wireless communication network 100 may include one or more tracking areas. A tracking area may include a set of cells managed by at least one base station. For example, tracking area 1, labeled as 140, includes cell 1, cell 2, and cell 3, and may further include more cells that may be managed by other base stations and are not shown in FIG. 1 . The wireless communication network 100 may also include at least one UE 160. The UE may select a cell from among multiple cells supported by the base station to communicate with the base station over the terrestrial (OTA) wireless communication interface and resources, and as the UE 160 travels within the wireless communication network 100, it may reselect a cell for communication. For example, the UE 160 may initially select cell 1 to communicate with the base station 124, and then reselect cell 2 at some later point in time. The cell selection or reselection by the UE 160 may be based on the wireless signal strength / quality of the various cells and other factors.

[0020] The wireless communication network 100 may be implemented as, for example, a 2G, 3G, 4G / LTE, or 5G cellular communication network. Correspondingly, the base stations 122 and 124 may be implemented as 2G base stations, 3G NodeBs, LTE eNBs, or 5G NR gNBs. The UE 160 may be implemented as a mobile or fixed communication device capable of accessing the wireless communication network 100. The UE 160 may include, but is not limited to, a mobile phone, a laptop computer, a tablet, a personal digital assistant, a wearable device, an Internet of Things (IoT) device, an MTC / eMTC device, a distributed remote sensor device, a roadside assistance device, an XR device, and a desktop computer. The UE 160 may also be generally referred to as a wireless communication device or a wireless terminal. The UE 160 may support sidelink communication to another UE via a PC5 interface.

[0021] Although the following description focuses on a cellular wireless communication system, as shown in Figure 1, the underlying principles are applicable to other types of wireless communication systems for paging wireless devices. These other wireless systems may include, but are not limited to, Wi-Fi, Bluetooth, ZigBee, and WiMax networks.

[0022] 2 illustrates an example of an electronic device 200 for implementing a network base station (e.g., a radio access network node), a core network (CN), and / or operations and maintenance (OAM). Optionally, in one implementation, the exemplary electronic device 200 may include radio transmit / receive (Tx / Rx) circuitry 208 for transmitting / receiving communications with UEs and / or other base stations. Optionally, in one implementation, the electronic device 200 may also include network interface circuitry 209 for communicating with the base station and / or other base stations and / or the core network, e.g., optical or wired interconnects, Ethernet, and / or other data transmission media / protocols. The electronic device 200 may optionally include an input / output (I / O) interface 206 for communicating with an operator or the like.

[0023] Electronic device 200 may also include system circuitry 204. System circuitry 204 may include processor 221 and / or memory 222. Memory 222 may include operating system 224, instructions 226, and parameters 228. Instructions 226 may configure one or more of processors 221 to perform the functions of a network node. Parameters 228 may include parameters to support execution of instructions 226. For example, the parameters may include network protocol settings, bandwidth parameters, radio frequency mapping assignments, and / or other parameters.

[0024] FIG. 3 illustrates an example of an electronic device for implementing a terminal device 300 (e.g., user equipment (UE)). The UE 300 may be a mobile device, such as a smartphone or a mobile communications module, located in a vehicle. The UE 300 may include some or all of the following: a communications interface 302, system circuitry 304, an input / output interface (I / O) 306, display circuitry 308, and storage 309. The display circuitry may include a user interface 310. The system circuitry 304 may include any combination of hardware, software, firmware, or other logic / circuitry. The system circuitry 304 may be implemented with, for example, one or more systems-on-chips (SoCs), application-specific integrated circuits (ASICs), discrete analog and digital circuits, and other circuitry. The system circuitry 304 may be part of the implementation of any desired functionality within the UE 300. In that regard, system circuitry 304 may include, by way of example, logic that facilitates music and video decoding and playback, e.g., MP3, MP4, MPEG, AVI, FLAC, AC3, or WAV decoding and playback, application launching, user input acceptance, saving and retrieving application data, and, by way of example, establishing, maintaining, and terminating cellular phone calls or data connections for Internet connectivity, wireless network connections, Bluetooth® connections, or other connections, and displaying related information on user interface 310. User interface 310 and input / output (I / O) interface 306 may include a graphical user interface, a touch-sensitive display, tactile feedback or other tactile output, voice or facial recognition input, buttons, switches, speakers, and other user interface elements.Additional examples of I / O interface 306 may include microphones, video and still image cameras, temperature sensors, vibration sensors, rotation and orientation sensors, headset and microphone input / output jacks, universal serial bus (USB) connectors, memory card slots, radiation sensors (e.g., IR sensors), and other types of inputs.

[0025] 3, the communications interface 302 may include radio frequency (RF) transmit (Tx) and receive (Rx) circuitry 316, which handles the transmission and reception of signals through one or more antennas 314. The communications interface 302 may include one or more transceivers. The transceiver may be a wireless transceiver including modulation / demodulation circuitry, digital-to-analog converters (DACs), shaping tables, analog-to-digital converters (ADCs), filters, waveform shapers, filters, preamplifiers, power amplifiers, and / or other logic for transmitting and receiving through one or more antennas or (for some devices) over a physical (e.g., wired) medium. The transmitted and received signals may conform to any of a diverse array of formats, protocols, modulations (e.g., QPSK, 16-QAM, 64-QAM, or 256-QAM), frequency channels, bit rates, and encodings. As one specific example, communication interface 302 may include a transceiver supporting transmission and reception under 2G, 3G, BT, WiFi, Universal Mobile Telecommunications System (UMTS), High Speed Packet Access (HSPA)+, 4G / Long Term Evolution (LTE), and 5G standards. However, the techniques described below are also applicable to other wireless communication technologies, whether arising from the 3rd Generation Partnership Project (3GPP), GSM Association, 3GPP2, IEEE, or other partnership or standards body.

[0026] 3 , system circuitry 304 may include one or more processors 321 and memory 322. Memory 322 stores, for example, an operating system 324, instructions 326, and parameters 328. Processor 321 is configured to execute instructions 326 to perform desired functionality for UE 300. Parameters 328 may provide and define configuration and operation options for instructions 326. Memory 322 may also store any BT, WiFi, 3G, 4G, 5G, or other data that UE 300 will transmit or is receiving through communication interface 302. In various implementations, system power for UE 300 may be supplied by a power storage device, such as a battery or a converter. Network deployment with dual connectivity

[0027] With the rapid evolution of wireless communication technologies, dual connectivity (DC) features are introduced to meet the demands for higher speeds, higher throughput and capacity, higher efficiency, and lower latency. Generally, in a DC deployment, a UE is connected to two base stations (i.e., two nodes) and is enabled to transmit / receive data through both base stations. The two base stations may be of the same type. For example, both base stations may be eNBs, gNBs, ng-eNBs, and the like. The two base stations may also be of different types. A core network to support a DC deployment may include, for example, an LTE Evolved Packet Core (EPC) or a 5G Core.

[0028] In a DC deployment, one of the nodes acts as a master node (MN) and the other acts as a secondary node (SN). In some example implementations, the MN is the node to which the UE initially connects. Subsequently, the UE may connect to the SN.

[0029] In some example implementations, the MN is used only to provide a control plane connection between the UE and the core network, while the SN provides additional resources for carrying user plane traffic.

[0030] In some example implementations, the SN may also carry signaling messages.

[0031] Exemplary DC configurations include EN-DC (E-UTRA-NR dual connectivity), NE-DC (NR-E-UTRA dual connectivity), NR-DC (New Radio dual connectivity), NGEN-DC (NG-RAN-E-UTRA dual connectivity), etc. Illustratively, an MN may be an eNB (in EN-DC), an ng-eNB (in NGEN-DC), or a gNB (in NR-DC and NE-DC). An SN may be an en-gNB (in EN-DC), an ng-eNB (in NE-DC), or a gNB (in NR-DC and NGEN-DC).

[0032] Under certain deployments, DCs may be configured in combination with carrier aggregation (CA), where both MNs and SNs may be associated with multiple cells or carriers. These aggregated carriers are collectively referred to as master cell groups (MCGs) and secondary cell groups (SCGs). Note that MCGs are associated with MNs, and SCGs are associated with SNs. Furthermore, note that an MCG may implicitly imply the MNs it associates with, and an SCG may implicitly imply the SNs it associates with.

[0033] For an example DC configuration, refer to Figure 4. In this example, the MCG 410 is associated with the MN, which is a gNB, and the SCG 412 is associated with the SN, which is an eNB.

[0034] An MCG may include a group of serving cells associated with an MN, including a primary cell (PCell) and, optionally, one or more secondary cells (Scells). An SCG may include a group of serving cells associated with an SN, including a primary SCG cell (PScell) and, optionally, one or more Scells. In Figure 4, MCG 410 is configured with one PCell and two Scells, namely, Scell1 and Scell2. SCG 412 is configured with one PScell and two Scells, namely, Scell1 and Scell2.

[0035] In some implementations, a UE may be connected to one MN but may switch from one SCG to another, or the UE may switch PScells within the same SCG. SN Add / Modify Procedure (MN Initiated)

[0036] In some example implementations, an SN may be added or changed (modified) by the MN. For example, a UE may switch from one SCG to another SCG (i.e., switch from one SN to another), and a PScell change will occur. Figure 5 illustrates an example overall message / signaling flow for SN addition / modification.

[0037] Step 1 The UE establishes a radio resource control (RRC) connection with the MN.

[0038] Step 2 The MN sends an SN Add / Modify request to the SN via the Xn-C to negotiate the resources, configuration, and algorithms (e.g., security algorithms) available at the SN. A new security key (K SN ) is required, the MN may calculate it and send it to the SN. The UE security capabilities and user plane (UP) security policy may also be sent to the SN.

[0039] The UE security capabilities may include capabilities for Next Generation Radio Access Network (NG-RAN), 5G Non-Access Stratum (NAS), 5G Access Stratum (AS), and may further include capabilities for Evolved Packet System (EPS), Universal Terrestrial Radio Access Network (UTRAN), and GSM EDGE Radio Access Network (GERAN) if these access types are supported by the UE. A UP security policy may be used to activate UP confidentiality and / or UP integrity for one or more DRBs belonging to a PDU session associated with the UE.

[0040] In case of PDU splitting, the UP integrity protection and cryptographic processing activation decision from the MN may also be included in the request.

[0041] Step 3 The SN allocates the necessary resources, such as radio resources, transport network resources, etc. The SN may also select the cryptographic and integrity algorithms that have the highest priority from its configured list and that are also present in the UE security capabilities. SN is delivered to the SN in step 2, the SN may calculate the RRC key as well as the UP key. The SN may then activate the UP security policy based on the UP key.

[0042] Step 4 The SN sends an SN Addition / Modification Acknowledgment to the MN indicating the availability of the requested resources and identifiers for the selected algorithms for the requested Data Radio Bearers (DRBs) and / or Signaling Radio Bearers (SRBs) for the UE. UP integrity protection and ciphering indications may also be sent to the MN.

[0043] Step 5 The MN sends an RRC connection reconfiguration request to the UE, instructing it to configure a new DRB and / or SRB for the SN. SN is required, and the UE must have K SN The MN forwards the UE configuration parameters (including the algorithm identifier received from the SN in step 4) and the UP integrity protection and ciphering indication (received from the SN in step 4) to the UE.

[0044] This message is sent via the RRC connection between the MN and the UE, and this RRCint Note that the SN counter is integrity protected using the RRC security key. Therefore, the SN counter cannot be tampered with.

[0045] Step 6 The UE receives the RRC connection reconfiguration request after verifying its integrity. If an SN counter parameter is included, the UE SN The UE may also calculate the required RRC and UP keys and activate RRC and UP protection according to the indications received for the associated SRBs and / or DRBs. The UE sends an RRC reconfiguration complete message to the MN. The UE may now elect to activate the selected ciphering / decryption and integrity protection keys with the SN.

[0046] Step 7 The MN may send an SN reconfiguration complete message to the SN, for example, via the Xn-C interface, to notify the SN of the configuration result. In response to receiving this message, the SN may choose to activate the selected encryption / decryption and integrity protection with the UE. Alternatively, if the SN does not activate encryption / decryption and integrity protection with the UE at this stage, the SN may activate encryption / decryption and integrity protection in response to receiving a random access request from the UE.

[0047] In this SN addition / modification procedure, K SN is used to secure the connection between the UE and the SN. The UE can authenticate itself with K SN can be calculated, while SN is SN With regard to the service of the same, we rely on MN.

[0048] In some example implementations, K SN may be derived by a key derivation function (KDF). The KDF may be based on the Hash-based Message Authentication Code Secure Hash Algorithm 256 (HMAC-SHA-256). Equation 1 below can be used to derive K SN An example for deriving [ka]

[0049] In Equation 1, the KDF has two inputs: an input key and a string S. The string S may be a concatenation of multiple strings, for example, by using Equation 2 below. [ka]

[0050] In Equation 2, FC is the function code. The concatenation has multiple parameters (P0 to Pn, where n is a non-negative integer) and a length for each parameter (i.e., L0, L1, ... Ln).

[0051] As an example, K SN To derive , the following inputs may be used: FC=0×79 P0 = value of the SN counter as a non-negative integer L0 = length of P0 (i.e., length of SN counter value)

[0052] The input key may be a key for the MN, which is K when the MN is an ng-eNB. eNB , when MN is gNB, K gNB may include: Selective SCG addition / modification using pre-configuration

[0053] In the SN addition / modification procedure described in the preceding section, the decision for SN addition / modification is made by the MN. Once the MN triggers the procedure, preparation efforts, including resource allocation, capability negotiation, and algorithm selection, need to be undertaken by the SN and the UE. Service delay may be introduced by the preparation efforts. Therefore, to expedite the procedure and shorten the duration of service interruption, it is desirable to reduce or even eliminate the preparation efforts so that once the SN addition / modification decision is made, the link between the UE and the SN can be established with minimized effort.

[0054] One solution is to move the preparation effort or preparation phase to an earlier stage before the SN addition / modification decision is made.

[0055] A UE may be pre-configured with a candidate SN pool containing multiple candidate SNs. For each candidate SN, the UE may be configured with configurations related to, for example, resource allocation, capability negotiation, algorithm selection, etc. The UE may also be configured with execution conditions used to evaluate and trigger SN addition or modification. For the same candidate SN, there may be different execution conditions serving different purposes, such as an execution condition for SN addition and an execution condition for SN modification. Furthermore, in some example implementations, a candidate SN may support multiple configurations, e.g., configurations serving different quality of service (QoS), different security levels, or different throughput. Correspondingly, the UE may evaluate multiple execution conditions for the candidate SN and select an SN configuration that matches the execution condition that is met.

[0056] The SN configuration may be used for conditional PScell addition (CPA) and / or conditional PScell change (CPC), in the sense that PScell addition and PScell change are triggered when the conditions defined by the execution conditions are met.

[0057] For an example, see Figure 6. A UE is configured with a candidate SN pool, which includes three candidate SNs (SN1-SN3). SN configurations and execution conditions 610, 612, and 614 are preconfigured in the UE. Based on these preconfigured configurations, the UE may add one of these SNs, add an SCG, or change its SCG from one SN to another. The UE may also change its PScell within the same SCG.

[0058] Similarly, for each candidate SN, pre-configuration may also be performed to support CPA / CPC procedures. For example, the candidate SN may be configured with UE capabilities and UE security preferences to minimize negotiation effort once the candidate SN is selected for SN addition or modification. Embodiment 1: Selective SCG Addition / Modification with Security Key Refresh

[0059] In this embodiment, the UE is pre-configured with candidate SN / SCG configurations to facilitate the CPC / CPA procedure. SN is synchronized between the UE and the target SN when the UE triggers the CPC / CPA procedure. SN Note that σ can be derived based on Equation 1, as explained above.

[0060] Under the CPA / CPC procedure, the UE may either add a new PScell or switch to another PScell in a different or the same SCG (or SN) according to the PCell in the MCG. The UE may keep a pre-configured SN / SCG configuration and may alternately switch to the same PScell multiple times. Depending on different PScell addition / switching scenarios, K for the SN is used to secure the link between the UE and the SN. SN may be reused or may need to be refreshed for added security. SN The refresh mechanism is explained in great detail.

[0061] When a UE is configured with multiple candidate SNs, a security key for the candidate SN, i.e., K, is used to secure the link between the UE and the candidate SNs. SN is used. SN may be derived based on Equations 1 and 2, as described above. In particular, the input key may be a security key for the MN, e.g., K if the MN is a gNB. gNB , or K if the MN is an ng-eNB. ng-eNB P0 may be an SN counter corresponding to the candidate SN.

[0062] In an exemplary implementation, all candidate SNs may be associated with the same MN, and therefore their individual K SN The input keys for deriving may also be the same.

[0063] K SN There are several security requirements for SN. First, each candidate SN must have its own unique K SN Second, for the same candidate SN, under certain conditions, SN A refresh requirement exists so that the data will need to be refreshed or updated. Further details will be explained in later paragraphs.

[0064] FIG. 7 shows an example signaling / message flow for a UE-initiated CPC / CPA procedure, including the following steps: Step 0

[0065] The UE may be pre-configured with a candidate SN pool (or SCG pool) including multiple candidate SNs (or multiple candidate SCGs). Referring back to FIG. 6, for each candidate SN, the UE maintains a configuration including a conditional PScell addition (CPA) configuration and / or a conditional PScell modification (CPC) configuration. The UE may also be pre-configured with execution conditions corresponding to the CPA and CPC configurations. For example, once the CPA execution condition is satisfied, a subsequent PScell addition may be performed according to the CPA configuration. For each candidate SN (or candidate SCG), the UE may also be pre-configured with an SN counter. For example, in FIG. 6, SN counters 616, 618, and 620 are assigned to SN1, SN2, and SN3, respectively. Once the SN counters are pre-configured with their respective initial values, the UE continues to maintain / update these counters.

[0066] In some example implementations, the MN may assign a unique initial value to each of the SN counters. For example, the initial values for the three SN counters 616, 618, and 620 shown in FIG. 6 may be 0, 1, and 2, respectively.

[0067] On the SN side, each candidate SN can be prepared in advance for the subsequent CPC / CPA run.

[0068] Step 1 The UE evaluates the execution conditions. If the CPA / CPC execution conditions are satisfied for a particular PScell under a candidate SN, the UE will select a PScell (and its associated candidate SN, also referred to as a target SN) and proceed with the CPA / CPC procedure. The execution conditions for CPA and CPC may be different.

[0069] As an example, referring to Figure 8, a UE is pre-configured with three candidate SNs, i.e., SN1, SN2, and SN3. Each SN has three cells, i.e., cell 1, cell 2, and cell 3. The UE has current dual connectivity, and the current PScell is cell 1 under SN1. The UE may select cell 2 under SN2 and perform a CPC procedure if the CPC execution condition is met. In this case, SN2 is the target SN.

[0070] Step 2 The UE triggers a CPC / CPA procedure toward a selected PScell by sending a CPC / CPA request message to the MN. The message may include at least one of an SN counter for the target SN (i.e., a candidate SN associated with the selected PScell) or an identifier, such as a PScell id, of the selected PScell to identify the target SN associated with the selected PScell. One of the goals for the UE to automatically forward the SN counter to the MN is to keep the SN counters synchronized between the UE and the MN. Therefore, it is also possible to include an SN counter update indication in the CPC / CPA request message instead of the SN counter itself, so that the UE and MN may update the SN counters in a synchronized manner.

[0071] The SN counter for the target SN associated with the selected PScell may or may not need to be refreshed from its current value. If the selected PScell is associated with a SN that is different from the SN associated with the current PScell in dual connectivity, the SN counter needs to be refreshed. K for the candidate SN SN also needs to be updated, and the UE will calculate K based on the refreshed SN counter. SN (i.e., the refresh for the SN counter is SN triggers an update).

[0072] As an example, referring to FIG. 8, assume that the current dual connectivity uses cell 1 as the PScell in SN1 (i.e., SN1 is the current SN), and the UE determines that the PScell needs to be changed to cell 2 under SN2. In this case, since the selected PScell is associated with an SN different from the current SN, the SN counter for SN2 (the target SN, which is the SN associated with the selected PScell) needs to be refreshed, and the K SN needs to be updated.

[0073] As another example, referring to Figure 8, assume that the current dual connectivity uses cell 1 in SN1 as the PScell (i.e., SN1 is the current SN), and the UE determines that the PScell needs to be changed to cell 2 under the same SN. In this case, there is no SN change, so the SN counter for the target SN, which is SN1, does not need to be refreshed, and the K SN may be reused without updating.

[0074] In some example implementations, the UE maintains an SN counter for each SN. When refreshing the SN counter for a selected (target) SN, the UE may determine the maximum value of all SN counters maintained by it, increase the maximum value by an offset (e.g., a predefined positive integer such as 1), and obtain a refreshed value for the SN counter of the selected SN, which may be greater than or equal to K for any candidate SN. SN Note that the offset is not used to calculate the MN. The offset may be configured by the MN.

[0075] As an example, assume that before an SN counter refresh, the UE maintains three SN counters with the following values: SN1 counter: 0, SN2 counter: 1, SN3 counter: 2.

[0076] Assuming the UE needs to refresh the SN counter for SN2 based on the decision logic described above, the UE first determines that the maximum value of all SN counters is 2 (i.e., the SN3 counter value), increments it by 1, obtains a refreshed value for the SN2 counter, and updates the SN2 counter. After the refresh, the three SN counters have the following values (with the updated SN2 counter value): SN1 counter: 0, SN2 counter: 3, SN3 counter: 2.

[0077] Since the SN counter has an upper limit, a reset for the counter will need to occur when the SN counter reaches its upper limit. Each reset results in a new cycle of the SN counter. In such a reset event, all SN counters may be reset, for example, to their initial pre-configured (e.g., set by the MN) values. Meanwhile, K SNThe input key to the KDF for deriving K will also be updated to a new key that has not been used before. Therefore, considering the SN counter reset, the requirement is that within each cycle of the SN counter, the refreshed counter value must be equal to the K for any candidate SN. SN should not be used to calculate

[0078] In some example implementations, the UE maintains an SN counter for each SN. The UE may also maintain a K SN The SN counter may be refreshed with a random number that has not been used to calculate SN. The SN counter reset rule may also be applied.

[0079] In response to receiving the updated SN counter, the MN stores it and, based on this, calculates the updated K SN Calculate.

[0080] Step 3 The MN sends an SN addition / modification request to the SN (i.e., the target SN), for example, via the Xn-C interface. The MN also receives a new K SN If is calculated in step 2, K SN Deliver to SN.

[0081] Step 4 The SN sends an SN Addition / Modification Request Acknowledgement message to the MN, for example, via the Xn-C interface. The SN may activate the selected encryption / decryption and integrity protection with the UE based on the pre-configured configuration. If the SN does not activate encryption / decryption and integrity protection with the UE at this stage, the SN may select to activate encryption / decryption and integrity protection in response to receiving a random access request from the UE. In step 3, the updated K SN When is sent to SN, encryption / decryption and integrity protection are performed on the updated K SN otherwise, the current K SNNote that may be used for security purposes.

[0082] Step 5 The MN sends a CPC / CPA Request Acknowledgement message to the UE. In response to receiving this message, the UE may now activate the selected encryption / decryption and integrity protection keys using the SN.

[0083] In this embodiment, the UE maintains an SN counter (e.g., SN counters 616, 618, and 620 in FIG. 6) for each candidate SN in the candidate SN pool. These counters may be configured to different initial values, for example, by the MN. When the UE switches to a PScell under a target SN that is different from the current SN associated with the current PScell, the SN counter for the target SN is refreshed and a new K SN will be calculated. Embodiment 2: Selective SCG Addition / Modification with Security Key Refresh

[0084] This embodiment is similar to embodiment 1, except that the UE maintains the SN counter in a different manner.

[0085] In some example implementations, the UE maintains an SN counter for each candidate SN in the candidate SN pool. Each of these SN counters is pre-configured with the same initial value (e.g., 0). When the UE determines that the SN counter associated with the target SN needs to be refreshed (by following similar logic as described in step 2 of embodiment 1), the UE may uniformly increment all SN counters by a predefined offset (e.g., a predefined positive integer such as 1), so that all SN counters keep the same value. Alternatively, the UE may increment all SN counters by K for any candidate SN. SN It may be uniformly set to the same random integer that is not also used to calculate SN. Note that the SN counter cycle concept as described in embodiment 1 may still be applied.

[0086] In some example implementations, instead of maintaining an SN counter for each candidate SN, a single SN counter is employed by the UE, which covers all candidate SNs. When the UE determines that the SN counter associated with the target SN needs to be refreshed (by following similar logic as described in step 2 of embodiment 1), the UE may increment the SN counter by a predefined offset (e.g., a predefined positive integer such as 1). Alternatively, the UE may increment the SN counter by K for any candidate SN. SN It may be set to a random integer that has not been used to calculate SN. Note that the SN counter cycle concept as described in embodiment 1 can still be applied.

[0087] The above description and accompanying drawings provide specific exemplary embodiments and implementations. However, the described subject matter can be embodied in a variety of different forms, and thus, it is intended that the covered or claimed subject matter be construed as not limited to any exemplary embodiments set forth herein. A reasonably broad scope for the claimed or covered subject matter is intended. Among other things, for example, the subject matter may be embodied as a method, device, component, system, or non-transitory computer-readable medium for storing computer code. Thus, embodiments may take the form of, for example, hardware, software, firmware, a storage medium, or any combination thereof. For example, the method embodiments described above may be implemented by a component, device, or system including a memory and a processor by executing computer code stored in the memory.

[0088] Throughout this specification and the claims, terms may have nuanced meanings that are suggested or implied in context beyond their explicitly stated meaning. Similarly, the phrase "in one embodiment / implementation" as used herein does not necessarily refer to the same embodiment, and the phrase "in another embodiment / implementation" as used herein does not necessarily refer to a different embodiment. For example, it is intended that claimed subject matter include any combination of exemplary embodiments, whether in whole or in part.

[0089] Generally, terminology can be understood, at least in part, from its usage in context. For example, terms such as "and," "or," or "and / or," as used herein, can include a variety of meanings that may depend, at least in part, on the context in which such terms are used. Typically, "or," when used to relate a list such as "A, B, or C," is intended to mean "A, B, and C," used herein in an inclusive sense, as well as "A, B or C," used herein in an exclusive sense. Additionally, as used herein, the term "one or more" can be used to describe any feature, structure, or characteristic in a singular sense, or to describe a combination of features, structures, or characteristics in a plural sense, depending, at least in part, on the context. Similarly, terms such as "a," "an," or "the" may be understood to convey singular usage or to convey plural usage, depending at least in part on the context. Additionally, the term "based on" may be understood as not intended to convey a necessarily exclusive set of factors, but instead may allow for the existence of additional factors not necessarily explicitly described, again depending at least in part on the context.

[0090] References to features, advantages, or similar language throughout this specification do not imply that all of the features and advantages that may be realized using the present solution should or are included in any single implementation thereof. Rather, language referring to features and advantages is understood to mean that the specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present solution. Thus, discussions of features and advantages and similar language throughout this specification may, but do not necessarily, refer to the same embodiment.

[0091] Furthermore, the described features, advantages, and characteristics of the solution may be combined in any suitable manner in one or more embodiments. Those skilled in the art will recognize, in light of the description herein, that the solution may be practiced without one or more of the specific features or advantages of a particular embodiment. In other cases, additional features and advantages may be recognized in some embodiments that may not be present in all embodiments of the solution.

Claims

1. 1. A method for wireless communication implemented by a wireless device in a wireless network, comprising: selecting a target primary secondary cell (PScell) in a radio access network (RAN) in response to an execution condition being satisfied, the target PScell being associated with a target secondary node (SN), the target SN being a member of a list of SNs, each SN in the list of SNs being associated with an SN counter, the SN counter associated with each SN in the list of SNs being used to calculate a security key for each SN in the list of SNs; determining whether an SN counter associated with the target SN needs to be updated; determining that the SN counter associated with the target SN needs to be updated, selecting a refreshed SN counter value, and updating at least the SN counter associated with the target SN with the refreshed SN counter value, wherein the refreshed SN counter value is different from any previous SN counter value shared between the wireless device and a master node; transmitting a first message to the master node requesting switching from a current PS cell to the target PS cell, the first message including the refreshed SN counter value; A method comprising:

2. Determining whether the SN counter associated with the target SN needs to be updated includes: determining, in response to the SN associated with the target PScell being different from the SN associated with the current PScell, that the SN counter associated with the target SN needs to be updated; The method of claim 1 , comprising:

3. The method of claim 1 , wherein the wireless device has dual connectivity with the RAN, the dual connectivity including a connection between the wireless device and the current PScell.

4. The method of claim 3 , wherein the dual connection further comprises a primary connection between the wireless device and the master node.

5. The method of claim 1 , wherein an initial value of the SN counter associated with each SN in the list of SNs is preconfigured to an integer value.

6. 6. The method of claim 5, wherein the initial value of the SN counter associated with each SN in the list of SNs is preconfigured by the master node to the same integer value.

7. updating at least the SN counter associated with the target SN with the refreshed SN counter value; updating the SN counter associated with each SN in the list of SNs; The method of claim 6, comprising:

8. Selecting the refreshed SN counter value comprises: monotonically increasing the maximum value among all values in an SN counter associated with said list of SNs by a predefined number to obtain said refreshed SN counter value; The method of any one of claims 1 to 7, comprising:

9. Selecting the refreshed SN counter value comprises: A method according to any one of claims 1 to 7, comprising selecting a random integer value as the refreshed SN counter value.

10. receiving a second message from the master node indicating that the target SN is ready to establish a secure connection with the wireless device based on a target SN key, the target SN key being derived based on the refreshed SN counter value; The method of any one of claims 1 to 7, further comprising:

11. deriving the target SN key based on the refreshed SN counter value; activating a security configuration associated with the target PScell based on the target SN key; The method of claim 10 further comprising:

12. Each of the master node and the SN comprises a base station, and the base station comprises: gNodeB (gNB), eNodeB (eNB), ng-eNodeB (ng-eNB), or Node B The method according to any one of claims 1 to 7, comprising one of:

13. 1. A method for wireless communication implemented by a master network node in a RAN of a wireless network, comprising: receiving, from a wireless device, a first message requesting switching of the wireless device from a current PScell to a target PScell, the first message including a refreshed SN counter value for updating an SN counter, the refreshed SN counter value indicating that a target SN associated with the target PScell is different from an SN associated with the current PScell; A method comprising:

14. The method of claim 13 , wherein the wireless device has dual connectivity with the RAN, the dual connectivity including a secondary connection between the wireless device and the current PScell.

15. The method of claim 14 , wherein the dual connectivity further comprises a primary connection between the wireless device and the master network node.

16. updating the SN counter with the refreshed SN counter value; updating a target SN key based on the refreshed SN counter value, wherein the updated target SN key is used to secure a link between a target PScell and the wireless device; and transmitting a second message to the target SN, the second message including the updated target SN key; The method of any one of claims 13-15, further comprising:

17. receiving a third message from the target SN in response to the second message; transmitting a fourth message to the wireless device in response to the first message, the fourth message triggering the wireless device to activate a security configuration associated with the target PScell based on the updated target SN key; 17. The method of claim 16, further comprising:

18. Each of the master network node and the SN comprises a base station, the base station comprising: gNodeB (gNB), eNodeB (eNB), ng-eNodeB (ng-eNB), or Node B The method according to any one of claims 13 to 15, comprising one of:

19. A device for wireless communication comprising a memory for storing computer instructions and a processor in communication with said memory, said processor being configured to perform a method according to any one of claims 1 to 18 when said processor executes said computer instructions.

20. 19. A computer program product comprising a non-transitory computer readable program medium having computer code stored thereon, the computer code, when executed by one or more processors, causing the one or more processors to perform a method according to any one of claims 1 to 18.

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