Terminal device and terminal device method

Abstract

The present disclosure relates to a communication device and a communication method. In one aspect, a terminal device (110) receives a MAC layer security setting from a network device (120). When a MAC CE is received, the terminal device performs at least one of decryption or integrity verification on the MAC CE based on the setting. In this way, MAC layer security can be ensured.

Description

[Technical Field]

[0001] TECHNICAL FIELD Embodiments of the present disclosure relate generally to the field of telecommunications, and more particularly to a communication apparatus and method for layer 1 (L1) / layer 2 (L2) triggered mobility (LTM). [Background technology]

[0002] When a user equipment (UE) moves from the coverage area of ​​one cell to the coverage area of ​​another cell, it may be necessary to perform a serving cell change, addition, or release. Currently, it has been proposed to trigger the serving cell change, addition, or release by lower layer signaling, such as L1 / L2 signaling, also referred to as LTM. This can reduce latency, overhead, and interruptions. However, the LTM solution is still incomplete and requires further development. Summary of the Invention [Problem to be solved by the invention]

[0003] Generally, embodiments of the present disclosure provide a communication method, apparatus, and computer storage medium for LTM. [Means for solving the problem]

[0004] In a first aspect, a terminal device is provided, the terminal device including a processor configured to cause the terminal device to receive a medium access control (MAC) layer security configuration from a network device, and, in response to determining that a medium access control control element (MAC CE) is received, perform at least one of decryption or integrity verification on the MAC CE based on the configuration.

[0005] In a second aspect, a terminal device is provided, the terminal device including a processor, the processor being configured to cause the terminal device to: start a timer for detecting a failure in cell switch according to a determination that a first MAC CE indicating a cell switch to a target candidate cell is received from a network device; determine that a random access procedure for cell switch is skipped; and stop the timer according to a determination that an indication of completion of the cell switch is received from the network device.

[0006] In a third aspect, a terminal device is provided, the terminal device including a processor configured to cause the terminal device to receive a MAC CE indicating a cell switch from a network device and, according to a determination that a partial MAC reset procedure is performed, enable periodic power headroom reporting (PHR).

[0007] In a fourth aspect, there is provided a terminal device, the terminal device including a processor configured to cause the terminal device to receive a MAC CE indicating a cell switch from a network device, and perform a service data unit (SDU) discard of a signal radio bearer (SRB) by a packet data convergence protocol (PDCP) entity of the network device.

[0008] In a fifth aspect, a communication method is provided, the method including: receiving, at a terminal device, a MAC layer security configuration from a network device; and, in accordance with determining that a MAC CE is received, performing at least one of decryption or integrity verification on the MAC CE based on the configuration.

[0009] In a sixth aspect, there is provided a communications method, the method including: starting, at the terminal device, a timer for detecting a failure in cell switch according to a determination that a first MAC CE indicating a cell switch to a target candidate cell is received from a network device; determining that a random access procedure for the cell switch is skipped; and stopping the timer according to a determination that an indication of completion of the cell switch is received from the network device.

[0010] In a seventh aspect, there is provided a communication method, the method including: receiving, at a terminal device, a MAC CE indicating a cell switch; and enabling a PHR according to a determination that a partial MAC reset procedure is performed.

[0011] In an eighth aspect, there is provided a communication method, the method including: receiving, in a terminal device, a MAC CE indicating a cell switch from a network device; and performing SDU discarding of the SRB by a PDCP entity of the network device.

[0012] In a ninth aspect, there is provided a computer-readable medium having stored thereon instructions that, when executed on at least one processor, cause the at least one processor to perform a method according to any of the fifth to eighth aspects of the present disclosure.

[0013] Other features of the present disclosure will become readily apparent from the following description. [Brief explanation of the drawings]

[0014] The above and other objects, features and advantages of the present disclosure will become more apparent through more detailed descriptions of several embodiments of the present disclosure in the accompanying drawings.

[0015] [Figure 1A] 1 illustrates an exemplary communication network in which some embodiments of the present disclosure may be implemented.

[0016] [Figure 1B]1 illustrates a schematic diagram illustrating network protocol layer entities that may be established for a user plane (UP) protocol stack in an apparatus, according to some embodiments of the present disclosure.

[0017] [Figure 1C] 1 illustrates a schematic diagram illustrating network protocol layer entities that may be established for a control plane (CP) protocol stack in an apparatus, according to some embodiments of the present disclosure.

[0018] [Figure 1D] FIG. 1 shows a schematic diagram illustrating the process of LTM in which some embodiments of the present disclosure can be implemented.

[0019] [Figure 2] FIG. 1 illustrates a schematic diagram illustrating a communication process for security of LTM according to an embodiment of the present disclosure.

[0020] [Figure 3] 1 shows a schematic diagram illustrating an exemplary MAC CE according to an embodiment of the present disclosure.

[0021] [Figure 4] FIG. 10 shows a schematic diagram illustrating another communication process for random access channel (RACH)-less LTM, according to an embodiment of the present disclosure.

[0022] [Figure 5] FIG. 10 shows a schematic diagram illustrating yet another communication process for a power headroom report (PHR), according to an embodiment of the present disclosure.

[0023] [Figure 6]1 illustrates a schematic diagram illustrating yet another communication process for discarding a service data unit (SDU) of a signal radio bearer (SRB), according to an embodiment of the present disclosure;

[0024] [Figure 7] 1 illustrates an exemplary communication method implemented in a terminal device, according to some embodiments of the present disclosure.

[0025] [Figure 8] 1 illustrates another exemplary communication method implemented in a terminal device, according to some embodiments of the present disclosure.

[0026] [Figure 9] 1 illustrates yet another exemplary communication method implemented in a terminal device, according to some embodiments of the present disclosure.

[0027] [Figure 10] 10 illustrates yet another exemplary communication method implemented in a terminal device, according to some embodiments of the present disclosure.

[0028] [Figure 11] FIG. 1 is a schematic block diagram of an apparatus suitable for practicing embodiments of the present disclosure.

[0029] Throughout the drawings, the same or similar reference numbers represent the same or similar elements. DETAILED DESCRIPTION OF THE INVENTION

[0030] The principles of the present disclosure will be described with reference to several embodiments. It should be understood that these embodiments are set forth for illustrative purposes only to aid those skilled in the art in understanding and practicing the present disclosure, and do not imply any limitations on the scope of the present disclosure. The present disclosure described in this disclosure can be implemented in various ways other than those described below.

[0031] In the following description and claims, unless defined otherwise, all technical and scientific terms used have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0032] As used herein, the term "terminal device" refers to any device with wireless or wired communication capabilities. Examples of terminal devices include User Equipment (UE), personal computers, desktops, mobile phones, cellular phones, smartphones, Personal Digital Assistants (PDAs), portable computers, tablets, wearable devices, Internet of Things (IoT) devices, Ultra-reliable and Low Latency Communication (URLLC) devices, Internet of Everything (IoE) devices, Machine Type Communication (MTC) devices, vehicle-mounted devices for V2X communications where X stands for pedestrian, vehicle, or infrastructure / network, devices for Integrated Access and Backhaul (IAB), satellite- or airborne vehicles in a Non-Terrestrial Network (NTN) including High Altitude Platforms (HAPs) including satellites and Unmanned Aircraft Systems (UASs), Augmented Reality (AR), Mixed Reality (MR), and other technologies. This includes, but is not limited to, extended reality (XR) devices that include different types of reality, such as virtual reality (VR), unmanned aerial vehicles (UAVs), which are aircraft without a human pilot and are commonly referred to as drones, devices on high-speed trains (HSTs), image capture devices such as digital cameras, sensors, gaming devices, music storage and playback devices, or internet devices that enable wireless or wired internet access and browsing.A "terminal device" may further have "multicast / broadcast" capabilities to support public safety and mission-critical, V2X applications, transparent IPv4 / IPv6 multicast distribution, IPTV, smart TV, wireless services, over-the-air software distribution, group communication, and IoT applications. It may also incorporate one or more Subscriber Identity Modules (SIMs), known as multi-SIM. The term "terminal device" may be used interchangeably with UE, mobile station, subscriber station, mobile terminal, user terminal, or wireless device.

[0033] The term "network device" as used herein means a device capable of providing or hosting a cell or coverage area in which a terminal device can communicate. Examples of network devices include, but are not limited to, a Node B (Node B or NB), an evolved Node B (eNode B or eNB), a next generation Node B (gNB), a Transmission Reception Point (TRP), a Remote Radio Unit (RRU), a Radio Head (RH), a Remote Radio Head (RRH), an IAB node, a low-power node such as a femto node or a pico node, a Reconfigurable Intelligent Surface (RIS), etc.

[0034] A terminal device or a network device may have artificial intelligence (AI) or machine learning capabilities, which generally include a model trained from a large amount of data collected for a specific function and can be used to predict some information.

[0035] The terminal device or network device may operate on several frequency ranges, such as FR1 (410 MHz to 7125 MHz), FR2 (24.25 GHz to 71 GHz), frequency bands greater than 100 GHz, and Terahertz (THz). It can also operate on licensed, unlicensed, and shared spectrum. The terminal device may have two or more connections with the network device under a Multi-Radio Dual Connectivity (MR-DC) application scenario. The terminal device or network device can operate in full duplex, flexible duplex, and cross-division duplex modes.

[0036] Embodiments of the present disclosure may be implemented in test equipment, such as, for example, a signal generator, a signal analyzer, a spectrum analyzer, a network analyzer, a test terminal device, a test network device, a channel emulator, and the like.

[0037] In one embodiment, a terminal device may be connected to a first network device and a second network device. One of the first network device and the second network device may be a master node, and the other may be a secondary node. The first network device and the second network device may use different radio access technologies (RATs). In one embodiment, the first network device may be a first RAT device, and the second network device may be a second RAT device. In one embodiment, the first RAT device is an eNB, and the second RAT device is a gNB. Information regarding the different RATs may be transmitted to the terminal device from at least one of the first network device or the second network device. In one embodiment, the first information may be transmitted from the first network device to the terminal device, and the second information may be transmitted from the second network device directly or via the first network device to the terminal device. In one embodiment, information regarding the terminal device configuration configured by the second network device may be transmitted from the second network device via the first network device. The information regarding the reconfiguration of the terminal device configured by the second network device may be transmitted to the terminal device directly from the second network device or via the first network device.

[0038] As used herein, the singular forms "a," "an," and "said" include the plural forms unless the context clearly indicates otherwise. The term "comprises" and variations thereof should be understood as open-ended terms meaning "including, but not limited to." The term "based on" should be understood as "based at least in part on." The terms "one embodiment" and "embodiment" should be understood as "at least one embodiment." The term "another embodiment" should be understood as "at least one other embodiment." Terms such as "first," "second," etc. may refer to different or the same object. The following may include other explicit and implicit definitions.

[0039] In some instances, values, procedures, or devices are referred to as "best," "lowest," "highest," "minimum," "maximum," etc. It should be understood that such descriptions are intended to illustrate that selections may be made from among many functional alternatives used, and that such selections are not necessarily better, smaller, higher, or otherwise more preferred than other selections.

[0040] In the context of this disclosure, the term "cell switch" may be used interchangeably with "reconfiguration due to secondary cell group (SCG) or master cell group (MCG) synchronization" or "cell change." The term "PSCell" refers to an SpCell of an SCG, the term "PCell" refers to an SpCell of an MCG, and the term "SpCell" refers to a primary cell of an SCG or MCG. The term "SCell" refers to a secondary cell. The term "lower layer signaling" may be used interchangeably with "L1 / L2 signaling." The term "RRC reconfiguration" may be used interchangeably with "RRC reconfiguration message." The term "candidate cell" may be used interchangeably with "LTM candidate cell." The term "target cell" may be used interchangeably with "target candidate cell," "candidate target cell," or "LTM target candidate cell."

[0041] An embodiment of the present disclosure provides a communication solution to further enhance the LTM solution. In one aspect, a network device sends a MAC layer security configuration to a terminal device. When a MAC CE is received, the terminal device performs at least one of decryption or integrity verification on the MAC CE based on the configuration. When a further MAC CE is sent, the terminal device performs at least one of encryption or integrity protection on the further MAC CE based on the configuration. In this way, MAC layer security can be ensured.

[0042] In another aspect, the network device transmits a MAC CE indicating a cell switch to the terminal device. The terminal device starts a timer for detecting a failure in the cell switch in response to the MAC CE. If the terminal device determines that the random access procedure for the cell switch is skipped, the terminal device stops the timer upon receiving an indication of completion of the cell switch from the network device. In this way, the completion of the RACH-less LTM can be indicated to the terminal device.

[0043] In yet another aspect, the network device sends a MAC CE to the terminal device indicating a cell switch. If the terminal device determines that a partial MAC reset procedure is to be performed, the terminal device enables PHR. In this way, periodic PHR can be triggered in the event of a partial MAC reset during LTM.

[0044] In yet another aspect, when the terminal device receives a MAC CE indicating a cell switch from the network device, the terminal device causes the PDCP entity of the terminal device to perform SDU discard of the SRB. In this way, PDCP SDU discard of the SRB can be triggered during LTM without RRC configuration for PDCP SDU discard.

[0045] The principles and implementations of the present disclosure are described in detail below with reference to the drawings. Communication Network Example

[0046] 1A illustrates a schematic diagram of an exemplary communication network 100A in which some embodiments of the present disclosure may be implemented. As shown in FIG. 1A, communication network 100A may include terminal device 110 and network device 120. Network device 120 provides multiple cells (shown as cells 121 and 122) that serve the terminal device.

[0047] It should be understood that the number of devices or cells in Figure 1A is shown for illustrative purposes and is not intended to imply any limitations on the present disclosure. Communications network 100A may include any suitable number of network devices and / or terminal devices and / or cells suitable for carrying out implementations of the present disclosure.

[0048] 1A, terminal device 110 may communicate with network device 120 via a channel, such as a wireless communication channel. Communications in communication network 100A may conform to any suitable standard, including, but not limited to, Global System for Mobile Communications (GSM), Long Term Evolution (LTE), LTE Evolution (LTE-Evolution), LTE Advanced (LTE-A), New Radio (NR), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA), GSM EDGE Radio Access Network (GERAN), Machine Type Communications (MTC), etc. Embodiments of the present disclosure may be performed in accordance with any generation of communication protocols now known or developed in the future. Examples of communication protocols include, but are not limited to, first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G) communication protocols, 5.5G, 5G-Advanced networks, or sixth generation (6G) networks.

[0049] Communications in the direction from terminal device 110 to network device 120 are referred to as uplink (UL) communications, and communications in the reverse direction from network device 120 to terminal device 110 are referred to as downlink (DL) communications. Terminal device 110 may move between cells of network device 120 and possibly other network devices. In UL communications, terminal device 110 may transmit UL data and control information to network device 120 over UL channels. In DL communications, network device 120 may transmit DL data and control information to terminal device 110 over DL channels.

[0050] Communications within the communication network 100A may be performed according to a UP and CP protocol stack. Generally, for a communication device (such as a terminal device or a network device), there are multiple entities for multiple network protocol layers in the protocol stack, which may be configured to perform corresponding processing on data or signaling transmitted from and received by the communication device. FIG. 1B illustrates a schematic diagram 100B illustrating network protocol layer entities that may be established for a UP protocol stack in a device, according to some embodiments of the present disclosure. As shown in FIG. 1B, in a UP, the terminal device 110 and the network device 120 may each include an L1 layer entity, i.e., a physical (PHY) layer entity (also referred to as a PHY entity), and one or more entities of higher layers (such as the L2 layer and Layer 3 (L3) layer, i.e., higher layers). The one or more entities in the higher layers include a medium access control (MAC) layer entity (also referred to as a MAC entity), a radio link control (RLC) layer entity (also referred to as an RLC entity), a packet data convergence protocol (PDCP) layer entity (also referred to as a PDCP entity), and a service data application protocol (SDAP) layer entity (also referred to as an SDAP entity, which will be established in 5G and higher generation networks). In some cases, the PHY, MAC, RLC, PDCP, and SDAP entities are stacked.

[0051] FIG. 1C illustrates a schematic diagram 100C illustrating network protocol layer entities that may be established for a CP protocol stack in an apparatus according to some embodiments of the present disclosure. As illustrated in FIG. 1C, in a CP, each of the terminal device 110 and the network device 120 may include an L1 layer entity, i.e., a PHY layer entity (also referred to as a PHY entity), and one or more entities of higher layers (L2 and L3 layers). The one or more entities of the higher layers may include a MAC layer entity (also referred to as a MAC entity), an RLC layer entity (also referred to as an RLC entity), a PDCP layer entity (also referred to as a PDCP entity), and a radio resource control (RRC) layer entity (also referred to as an RRC entity). The RRC layer may also be referred to as an access stratum (AS) layer, and thus the RRC entity may also be referred to as an AS entity. As illustrated in FIG. 1C, the terminal device 110 may also include a non-access stratum (NAS) layer entity (also referred to as a NAS entity). The NAS layer on the network side is not located in a network device, but in a core network (CN, not shown). In some cases, these entities have a stack structure.

[0052] In the context of this disclosure, L1 refers to the PHY layer, L2 refers to the MAC layer or the RLC layer or the PDCP layer or the SDAP layer, and L3 refers to the RRC layer. In the context of this disclosure, L1 or L2 may also be collectively referred to as a lower layer, and L3 may also be referred to as an upper layer. Accordingly, signaling of L1 or L2 may also be referred to as lower layer signaling, and L3 signaling may also be referred to as upper layer signaling.

[0053] Generally, communication channels are classified into logical channels, transmission channels, and physical channels. Physical channels are channels through which the PHY layer actually transmits information. For example, physical channels may include a physical uplink control channel (PUCCH), a physical uplink shared channel (PUSCH), a physical random-access channel (PRACH), a PDCCH, a physical downlink shared channel (PDSCH), and a physical broadcast channel (PBCH).

[0054] The transmission channels are channels between the PHY layer and the MAC layer, and may include, for example, a broadcast channel (BCH), a downlink shared channel (DL-SCH), a paging channel (PCH), an uplink shared channel (UL-SCH), and a random access channel (RACH).

[0055] Logical channels are channels between the MAC layer and the RLC layer, and may include, for example, a dedicated control channel (DCCH), a common control channel (CCCH), a paging control channel (PCCH), a broadcast control channel (BCCH), and a dedicated traffic channel (DTCH).

[0056] Generally, a channel between the RRC layer and the PDCP layer is called a radio bearer. At least one data radio bearer (DRB) for carrying data plane data and at least one signaling radio bearer (SRB) for carrying control plane data may be configured in the terminal device 110. Four types of SRBs, SRB0, SRB1, SRB2, and SRB3, may be defined in the RRC layer. SRB0 uses the CCCH for establishing or re-establishing an RRC connection. SRB1 uses the DCCH and is established when an RRC connection is established. SRB2 uses the DCCH and is established during RRC re-configuration and after initial security activation. SRB3 uses the DCCH and is established between the terminal device 110 and the SN when a dual connection is established.

[0057] 1A , in some embodiments, terminal device 110 may be located within the coverage of cell 121 of network device 120, and terminal device 110 may communicate with network device 120 based on a network configuration. In this case, cell 121 may be referred to as a serving cell of terminal device 110. Cell 122 may be referred to as an LTM candidate cell for terminal device 110.

[0058] In some embodiments, terminal device 110 may establish a dual connection (i.e., a simultaneous connection) with network device 120 and another network device (not shown). In some embodiments, network device 120 may serve as a master node (MN). In these embodiments, terminal device 110 may communicate with network device 120 via a set of serving cells. The set of serving cells forms an MCG, and a primary cell within the MCG is referred to as a PCell. In some scenarios, the PCell may change from cell 121 to cell 122, which is referred to as a handover (HO). In some embodiments, network device 120 may serve as a secondary node (SN). In these embodiments, the set of serving cells provided by network device 120 forms an SCG, and a primary cell within the SCG is referred to as a PSCell. In some scenarios, the PSCell may change from cell 121 to cell 122, which is referred to as a PSCell change.

[0059] In some scenarios, the network device 120 may receive an L1 measurement report from the terminal device 110. Based on the L1 measurement report, the network device 120 may change the serving cell of the terminal device 110 via the MAC CE. This procedure is called LTM. The network device 120 may prepare one or more candidate cells and provide the candidate cell configurations to the terminal device 110 via an RRC message. Then, the network device 120 selects one of the candidate cell configurations as a target configuration for LTM, thereby triggering an LTM cell switch.

[0060] The cell switch trigger information may be conveyed in a MAC CE including at least a candidate configuration index. Cell-specific configuration, radio bearer configuration, and measurement configuration may be part of the LTM candidate cell configuration. The terminal device 110 may perform contention-based random access (CBRA) or contention-free random access (CFRA) in cell switch. If the terminal device 110 does not need to acquire the timing advance (TA) of the target cell during cell switch, the terminal device 110 may also skip the random access procedure. The RACH resource for CFRA may be provided in the RRC configuration.

[0061] FIG. 1D shows a schematic diagram illustrating a process 100D of LTM capable of implementing some embodiments of the present disclosure. For purposes of discussion, process 100D will be described with reference to FIG. 1A. Process 100D may involve terminal device 110 and network device 120 as shown in FIG. 1A. Network device 120 may be an MN or SN serving terminal device 110. In this example, network device 120 provides a serving cell to terminal device 110 and also provides one or more candidate cells to terminal device 110.

[0062] 1D , in the LTM preparation phase, terminal device 110 may send a measurement report message to network device 120 (140). Network device 120 may decide to use LTM (141) and begin preparing LTM candidates. Network device 120 may send an RRCReconfiguration message to terminal device 110 (142) including configurations of one or more LTM candidate target cells. Terminal device 110 may store the configurations of the LTM candidate target cells and send an RRC reconfiguration complete message to network device 120 (143).

[0063] In an early synchronization (ie, early sync) phase, the terminal device 110 may perform DL synchronization and TA acquisition with a candidate target cell before receiving the LTM cell switch command (144).

[0064] In the LTM execution phase, the terminal device 110 may perform L1 measurements on the configured LTM candidate target cell and transmit a lower layer measurement report to the network device 120 (145). The network device 120 may decide to perform an LTM cell switch to the target cell (146) and transmit a MAC CE that triggers the LTM cell switch by including the candidate configuration index of the target cell (147). The terminal device 110 may switch to the configuration of the LTM candidate target cell (148). If a TA is not available, the terminal device 110 may perform a random access (RA) procedure toward the target cell (149).

[0065] In the LTM completion stage, the terminal device 110 may indicate that the LTM cell switch to the target cell has been successfully completed (150).

[0066] Embodiments of the present disclosure provide communication solutions for LTM, which will be described with reference to FIGS. Example Implementation of MAC Layer Security

[0067] In traditional HO, RRC messages are used for HO commands and measurement-related messages, and ciphering and integrity checks are performed to ensure security. In LTM, the cell switch command is sent by the MAC CE. However, MAC layer security is not yet supported, which may introduce security risks into the LTM procedure.

[0068] In view of this, embodiments of the present disclosure provide a communication solution for MAC layer security, which will now be described in conjunction with FIG.

[0069] 2 shows a schematic diagram illustrating a communication process 200 for LTM security in accordance with an embodiment of the present disclosure. For purposes of discussion, process 200 will be described with reference to FIG. 1A. Process 200 may involve terminal device 110 and network device 120 as shown in FIG. 1A. In this example, network device 120 provides terminal device 110 with a serving cell (e.g., cell 121) and also provides terminal device 110 with one or more candidate cells. The serving cell may be the SPCell, PCell, or PSCell of terminal device 110.

[0070] As shown in FIG. 2, the network device 120 may send 210 a configuration for MAC layer security to the terminal device 110.

[0071] In some embodiments, the configuration may include a configuration for encryption (also referred to herein as a first configuration for convenience). In some embodiments, the first configuration may include an encryption algorithm. In some embodiments, the first configuration may include an indication of whether encryption is enabled. For example, if the encryption algorithm of the PDCP layer (i.e., the encryption algorithm configured by the securityConfig IE) is reused for the MAC layer, the first configuration may include an indication of whether encryption is enabled or disabled. It should be understood that the first configuration may include a combination of the above information.

[0072] In some embodiments, the configuration may include a configuration for integrity protection (also referred to herein as a second configuration for convenience). In some embodiments, the second configuration may include an integrity protection algorithm. In some embodiments, the second configuration may include an indication of whether integrity protection is enabled. For example, if the integrity protection algorithm of the PDCP layer (i.e., the integrity protection algorithm configured by the securityConfig IE) is reused for the MAC layer, the second configuration may include an indication of whether integrity protection is enabled or disabled. It should be understood that the second configuration may include a combination of the above information.

[0073] It should also be understood that the MAC layer security configuration may include both the first configuration and the second configuration. That is, the MAC layer security configuration may include the configuration of the integrity protection function and the encryption function. Upon receiving the MAC layer security configuration, the terminal device 120 may configure the encryption function and the integrity function of the MAC entity using at least one of an encryption algorithm, an integrity protection algorithm, an encryption key, or an integrity protection key.

[0074] Referring to FIG. 2, in some embodiments, network device 120 may send 220 a MAC CE to terminal device 110. In some embodiments, the MAC CE may indicate LTM. In other words, the MAC CE may be used to trigger an LTM cell switch. It should be understood that other suitable MAC CEs are possible. In some embodiments, at least one of an integrity protection function or an encryption function may be applied to at least the MAC CE.

[0075] In some embodiments, the MAC CE may include at least one of a MAC CE sequence number or a message authentication code for integrity (MAC-I). In some embodiments, the MAC CE sequence number may also be referred to as a MAC CE count value. It should be understood that the MAC CE may also include MAC CE content (i.e., control fields). For a MAC CE that triggers an LTM cell switch, the content may include at least one of a candidate configuration index, a TCI state to be activated for the target candidate cell, or TA information of the target candidate cell.

[0076] Upon receiving the MAC CE from the network device 120, the terminal device 110 may perform at least one of decryption or integrity verification on the MAC CE (230).

[0077] In some embodiments, terminal device 110 may perform decryption on the MAC CE. In some embodiments, terminal device 110 may determine a set of input parameters including at least one of a sequence number (i.e., count) of the MAC CE, a logical channel identity (LCID) of the MAC CE, a downlink (DL) direction, or a key for encryption. Terminal device 110 may perform decryption on the MAC CE based on the set of input parameters. For example, terminal device 110 may perform decryption on the MAC CE by inputting the set of input parameters into an encryption algorithm.

[0078] In some embodiments, the encryption key may be a key defined for MAC layer encryption. In some embodiments, the encryption key may be a key for user plane (UP) traffic, e.g., K UPenc In some embodiments, the key for encryption may be a key for RRC signaling, e.g., K RRCencIt should be understood that the encryption key may be defined in any other suitable manner.

[0079] In some embodiments, terminal device 110 may perform integrity verification on the MAC CE. In some embodiments, terminal device 110 may determine a set of input parameters including at least one of a sequence number (i.e., count) of the MAC CE, an LCID of the MAC CE, a DL direction, or a key for integrity protection. Terminal device 110 may perform integrity verification on the MAC CE based on the set of input parameters. For example, terminal device 110 may perform integrity verification on the MAC CE by inputting the set of input parameters into an integrity protection algorithm.

[0080] In some embodiments, the key for integrity protection may be a key defined for MAC layer integrity protection. In some embodiments, the key for integrity protection may be a key for user plane (UP) traffic, e.g., K UPint In some embodiments, the key for integrity protection may be a key for RRC signaling, e.g., K RRCint It should be understood that the key for integrity protection may be defined in any other suitable manner.

[0081] In some embodiments where both encryption and integrity protection are performed on the MAC CE, terminal device 110 may first perform decryption and then integrity verification. In some embodiments, the decrypted data unit may include the MAC-I and the contents of the MAC CE. In some embodiments, the integrity verified data unit may include the contents of the MAC CE before encryption and a sequence number.

[0082] In some embodiments, if the integrity verification fails, the MAC layer of terminal device 110 may indicate the integrity verification failure to a higher layer (e.g., the RRC layer) of terminal device 110. In some embodiments, the MAC layer of terminal device 110 may discard the MAC PDU containing the MAC CE and consider the MAC PDU as not received. In some embodiments, when the RRC layer of terminal device 110 receives an integrity verification failure indication from a lower layer (i.e., the MAC layer), the RRC layer of terminal device 110 may trigger an RRC connection re-establishment procedure.

[0083] In some embodiments, terminal device 110 may expect to transmit a further MAC CE to network device 120. In some embodiments, the MAC CE may indicate completion of the LTM cell switch. It should be understood that other suitable MAC CEs are possible. Continuing with reference to FIG. 2, terminal device 110 may perform at least one of ciphering or integrity protection to generate the further MAC CE to be transmitted (240).

[0084] In some embodiments, terminal device 110 may perform encryption to generate the further MAC CE. In some embodiments, terminal device 110 may determine a set of input parameters including at least one of a sequence number (i.e., count) of the further MAC CE, an LCID of the further MAC CE, a UL direction, or a key for encryption. Terminal device 110 may perform encryption based on the set of input parameters. For example, terminal device 110 may perform encryption by inputting the set of input parameters into an encryption algorithm.

[0085] In some embodiments, terminal device 110 may perform integrity protection for generation of the further MAC CE. In some embodiments, terminal device 110 may determine a set of input parameters including at least one of a sequence number (i.e., count) of the further MAC CE, an LCID of the MAC CE, a UL direction, or a key for integrity protection. Terminal device 110 may perform integrity protection based on the set of input parameters. For example, terminal device 110 may perform integrity protection by inputting the set of input parameters into an integrity protection algorithm.

[0086] In some embodiments where both encryption and integrity protection are performed to generate a further MAC CE, terminal device 110 may first perform integrity protection and then encryption. In some embodiments, the integrity protected data unit may include the sequence number and contents of the MAC CE. In some embodiments, the encrypted data unit may include the contents of the MAC CE before encryption and the MAC-I.

[0087] Once the further MAC CE is generated, terminal device 110 may transmit (250) the further MAC CE to network device 120. In some embodiments, the further MAC CE may include at least one of a sequence number or a MAC-I of the further MAC CE. It should be appreciated that the further MAC CE may also include the content of the further MAC CE (i.e., a control field).

[0088] The embodiments of the present disclosure provide a design of a MAC CE that enables at least one of integrity protection and encryption. The MAC CE may include a content (i.e., a control field) and at least one of a MAC CE sequence number or a MAC-I.

[0089] FIG. 3 illustrates a schematic diagram 300 illustrating an exemplary MAC CE according to an embodiment of the present disclosure. As shown in FIG. 3, in some embodiments, MAC CE 310 may include a sequence number and content after the sequence number. In some embodiments, MAC CE 320 may include content and a sequence number after the content. In some embodiments, MAC CE 330 may include a sequence number, content after the sequence number, and a MAC-I after the content. In some embodiments, MAC CE 340 may include content, a sequence number after the content, and a MAC-I after the sequence number. In some embodiments, MAC CE 350 may include content, a MAC-I after the content, and a sequence number after the MAC-I.

[0090] In some embodiments where the MAC CE triggers the LTM, the contents of the MAC CE may include at least one of a candidate configuration index, a transmission configuration indication (TCI) state to be activated for the target cell, or TA information of the target cell.

[0091] So far, the solutions for MAC layer security have been described, and thus MAC CEs transmitted between terminal devices and network devices can be transmitted securely. Example Implementation of RACH-less LTM

[0092] Conventionally, when completing LTM, the terminal device sends an indication to the target candidate cell, and the terminal device needs to receive a response from the network as an indication of completion. However, if the RA procedure is omitted for LTM, the response from the network becomes unclear.

[0093] In view of this, embodiments of the present disclosure provide a solution for RACH-less LTM, which will be described below in conjunction with FIG.

[0094] 4 shows a schematic diagram illustrating another communication process 400 for RACH-less LTM according to an embodiment of the present disclosure. For purposes of discussion, process 400 will be described with reference to FIG. 1A. Process 400 may involve terminal device 110 and network device 120 as shown in FIG. 1A. In this example, network device 120 provides a serving cell (e.g., cell 121) to terminal device 110 and also provides a target candidate cell (e.g., cell 122) to terminal device 110. The serving cell may be an SPCell, PCell, or PSCell of terminal device 110.

[0095] 4, network device 120 (e.g., a serving cell) may transmit 410 a MAC CE indicating a cell switch to the target candidate cell to terminal device 110. In other words, terminal device 110 may receive a MAC CE that triggers a cell switch to the target candidate cell.

[0096] The terminal device 110 may start a timer for detecting a failure in cell switching based on the reception of the MAC CE (420). For example, the RRC layer or the MAC layer of the terminal device 110 may start an LTM failure detection timer.

[0097] Continuing with reference to FIG. 4, the terminal device 110 may determine 430 that the RA procedure for cell switching is skipped. In some embodiments, if a TA value is provided in the MAC CE that triggers the cell switch, the terminal device 110 may determine to skip the RA procedure. In some embodiments, if a time alignment timer is running for a timing advance group (TAG) to which the target candidate cell belongs, the terminal device 110 may determine to skip the RA procedure. It should be understood that skipping the RA procedure may be determined based on a combination of the above information.

[0098] 4, upon determining that the RA procedure is skipped, terminal device 110 begins performing PDCCH monitoring for a cell-radio network temporary identity (C-RNTI) in the target candidate cell 440. Terminal device 110 may transmit an indication of completion of cell switching to the target candidate cell (also referred to herein as a second indication for convenience) to network device 120 (e.g., the target candidate cell 450). Transmission 450 may be referred to as an initial transmission to the target candidate cell.

[0099] In some embodiments, terminal device 110 may transmit the second indication via an UL grant configured for the first MAC CE. In some embodiments, terminal device 110 may transmit the second indication via an UL grant configured for a configuration associated with the target candidate cell. In some embodiments, terminal device 110 may transmit the second indication via an UL grant received from a PDCCH transmission of the target candidate cell addressed to the identity of terminal device 110 (e.g., an UL grant received from the PDCCH of the target candidate cell for the C-RNTI of the MAC entity). It should be understood that the second indication may be transmitted via any combination of the above uplink grants. In some embodiments, any of the uplink grants may be configured uplink grants. In some embodiments, any of the uplink grants may be dynamic uplink grants.

[0100] In some embodiments, the second indication may be carried by an RRC message. In some embodiments, the second indication may be carried by a MAC CE. In some embodiments where the second indication is carried by a MAC CE (also referred to herein as a third MAC CE for convenience), the MAC CE may have a higher priority than data from any logical channel and a lower priority than data from an uplink common control channel (UL-CCCH). In other words, when the second indication is carried by a MAC CE, the MAC CE may have a higher priority than "data from any logical channel except data from the UL-CCCH."

[0101] 4, the network device 120 (e.g., the target candidate cell) may transmit (460) an indication of completion of the cell switch (also referred to herein as a first indication for convenience) to the terminal device 110. In other words, the terminal device 110 may receive the first indication from the target candidate cell.

[0102] In some embodiments, the first indication may be a PDCCH transmission (also referred to herein as the first PDCCH transmission for convenience) that includes a DL allocation and is directed to the identity of terminal device 110. For example, the first indication may be a PDCCH transmission that includes a DL allocation and is directed to the C-RNTI of terminal device 110. In other words, the first indication may be a DL allocation in the PDCCH for the C-RNTI of the MAC entity.

[0103] In some embodiments, the first indication may be a PDCCH transmission (also referred to herein as a second PDCCH transmission for convenience) including an UL grant and addressed to the identity of terminal device 110. For example, the first indication may be a PDCCH transmission including an UL grant and addressed to the C-RNTI of terminal device 110. In other words, the first indication may be an UL grant in the PDCCH for the C-RNTI of the MAC entity.

[0104] In some embodiments, the first indication may be a PDCCH transmission (also referred to herein as a third PDCCH transmission for convenience) addressed to the identity of terminal device 110, including an UL grant for the transmission to be performed (i.e., the new transmission). For example, the first indication may be a PDCCH transmission addressed to the C-RNTI of terminal device 110, including an UL grant for the new transmission. In other words, the first indication may be an UL grant for the new transmission on the PDCCH for the C-RNTI of the MAC entity.

[0105] In some embodiments, the first instruction may be a PDCCH transmission (also referred to herein as the fourth PDCCH transmission for convenience) addressed to the identity of terminal device 110, including an UL grant for an performed transmission (also referred to herein as the first transmission for convenience), the first transmission having the same hybrid automatic repeat request (HARQ) process as the performed transmission (also referred to herein as the second transmission for convenience). For example, the first instruction may be a PDCCH transmission addressed to the C-RNTI of terminal device 110, including an UL grant for a new transmission for the same HARQ process as the initial transmission. In other words, the first instruction may be an UL grant for a new transmission for the same HARQ process as the initial transmission on the PDCCH for the C-RNTI of the MAC entity.

[0106] In some embodiments, the first indication may be a MAC CE (also referred to herein as a second MAC CE) in a physical downlink shared channel (PDSCH) indicated by a PDCCH transmission (also referred to herein as a fifth transmission for convenience) addressed to the identity of the terminal device 110. For example, the first indication may be a MAC CE in a PDSCH indicated by a PDCCH addressed to the C-RNTI of the terminal device 110. In some embodiments, the second MAC CE may be an existing MAC CE. In some embodiments, the second MAC CE may be one of multiple existing MAC CEs. In some embodiments, the second MAC CE may be different from the first MAC CE indicating the cell switch. In this case, it is not necessary to define a new MAC CE, and extra signaling overhead can be saved. In some embodiments, the second MAC CE may be a newly defined MAC CE with a fixed size of zero bits. In some embodiments, the second MAC CE may be a UE contention resolution identity MAC CE.

[0107] 4, terminal device 110 may stop the timer upon receiving the first indication (470). For example, the MAC layer of terminal device 110 may send an indication to the RRC layer of terminal device 110 that a first indication of completion of the cell switch has been received from network device 120, after which the RRC layer may stop the timer. Alternatively, the MAC layer may stop the timer.

[0108] So far, we have described a solution for RACH-less LTM. In this way, if the RA procedure is skipped, LTM can be considered to have been completed successfully. Example Implementation of PHR Instructions for LTM

[0109] For LTM, to further reduce service interruption time, the conventional MAC reset procedure may be avoided in some cases, such as intra-DU (intra-distributed unit) LTM. Instead, the terminal device may perform a partial MAC reset procedure (sometimes called an LTM-specific MAC reset) during LTM. However, it is still unclear how to enable periodic PHR in the case of partial MAC reset.

[0110] In view of this, embodiments of the present disclosure provide a solution for PHR, which will be described below in conjunction with FIG.

[0111] 5 shows a schematic diagram illustrating a communication process 500 for PHR according to an embodiment of the present disclosure. For purposes of discussion, process 500 will be described with reference to FIG. 1A. Process 500 may involve terminal device 110 and network device 120 as shown in FIG. 1A. In this example, network device 120 provides a serving cell (e.g., cell 121) to terminal device 1105. The serving cell may be an SPCell, PCell, or PSCell of terminal device 110.

[0112] 5, the network device 120 transmits a MAC CE indicating a cell switch to the terminal device 110 (510), that is, an LTM is triggered.

[0113] Upon receiving the MAC CE, terminal device 110 determines that a partial MAC reset procedure is to be performed (520). In some embodiments, in the case of a partial MAC reset or an LTM-specific MAC reset, terminal device 110 may skip "cancelling a triggered buffer status reporting (BSR) procedure (if any)." In other words, terminal device 110 may maintain the BSR for the partial reset. In some embodiments, terminal device 110 may skip "initializing Bj for each logical channel to zero." In other words, terminal device 110 may maintain logical channel Bj. In some embodiments, terminal device 110 may skip "flushing DL HARQ soft buffers." In other words, terminal device 110 may not flush DL HARQ soft buffers. In some embodiments, terminal device 110 may skip "setting new data indicators (NDIs) for all uplink HARQ processes to the value 0." In other words, terminal device 110 may not set the NDI for the UL HARQ process to 0. In some embodiments, terminal device 110 may skip the "cancellation of a triggered recommended bitrate query procedure (if any)." In other words, terminal device 110 may not cancel a triggered recommended bitrate query procedure.

[0114] Continuing with reference to FIG. 5, terminal device 110 may enable periodic PHR (530) upon determining that a partial MAC reset procedure is to be performed.

[0115] In some embodiments for enabling periodic PHR, terminal device 110 may start or restart a timer for periodic PHR (e.g., phr-PeriodicTimer). In some embodiments, terminal device 110 may start or restart phr-PeriodicTimer if the MAC entity of terminal device 110 has UL resources allocated for a new transmission and this is the first UL resource allocated for a new transmission since the last partial MAC reset.

[0116] In some alternative embodiments, terminal device 110 may maintain a timer during the partial MAC reset procedure. In other words, terminal device 110 may not stop the phr-PeriodicTimer during the partial MAC reset procedure.

[0117] In this way, periodic PHR reporting may be triggered in case of a partial MAC reset during LTM. Example implementation of SRB SDU discard

[0118] Conventionally, PDCP SDU discarding for one SRB is performed only if the IE discardOnPDCP is set in the radio bearer configuration. However, in the case of LTM, the radio bearer configuration is configured optionally, so the network may not be able to dynamically set the IE discardOnPDCP.

[0119] In view of this, embodiments of the present disclosure provide a solution to SRB SDU discard, which will be described below in conjunction with FIG.

[0120] 6 shows a schematic diagram illustrating yet another communication process 600 for SDU discard of an SRB. For purposes of discussion, process 600 will be described with reference to FIG. 1A. Process 600 may involve terminal device 110 and network device 120 as shown in FIG. 1A. In this example, network device 120 provides a serving cell (e.g., cell 121) to terminal device 110. The serving cell may be an SPCell, PCell, or PSCell of terminal device 110.

[0121] 6, the network device 120 transmits a MAC CE indicating a cell switch to the terminal device 110 (610), that is, an LTM is triggered.

[0122] Upon receiving the MAC CE, terminal device 110 causes a PDCP entity of terminal device 110 to perform SDU discard of the SRB (620). In other words, terminal device 110 implicitly, or without any configuration or instruction from the network, or without any configuration or instruction from the network, triggers the PDCP entity of the SRB to perform SDU discard. In some embodiments, the SRB may be at least SRB1.

[0123] In some embodiments, upon receiving a MAC CE indicating a cell switch, the MAC entity of the terminal device 110 may indicate the cell switch to the RRC layer of the terminal device 110, and the RRC layer may indicate to the lower layer (i.e., the PDCP layer) to perform SDU discard of the SRB.

[0124] In some alternative embodiments, upon receiving a MAC CE indicating a cell switch, the MAC layer of terminal device 110 may indicate to upper layers (ie, PDCP layer) to perform SDU discard of the SRB.

[0125] In this way, when an LTM is triggered or a MAC CE indicating a cell switch is received, the terminal device may implicitly or without any configuration or instruction from the network trigger the PDCP entity to perform SDU discard of the SRB.

[0126] It should be understood that the processes 200, 400, 500, 600 may be performed separately or in any suitable combination. Exemplary implementation of the method

[0127] In response to the above, embodiments of the present disclosure provide communication methods implemented in a terminal device, which are described below with reference to FIGS.

[0128] 7 illustrates an exemplary communication method 700 implemented in a terminal device according to some embodiments of the present disclosure. For example, method 700 may be performed in terminal device 110 as shown in FIG. 1A. For purposes of discussion, method 700 is described below with reference to FIG. 1A. It should be understood that method 700 may include additional blocks not shown and / or omit some blocks shown, and that the scope of the present disclosure is not limited in this respect.

[0129] At block 710, terminal device 110 receives configurations for MAC layer security from network device 120. In some embodiments, the configurations may include at least one of a first configuration for encryption or a second configuration for integrity protection.

[0130] In some embodiments, the first configuration may include at least one of an indication of whether encryption is enabled or an encryption algorithm, and in some embodiments, the second configuration may include at least one of an indication of whether integrity protection is enabled or an integrity protection algorithm.

[0131] In block 720, terminal device 110 determines that a MAC CE has been received. In some embodiments, the MAC CE may indicate an LTM. In some embodiments, the MAC CE includes at least one of a MAC CE sequence number or a MAC-I.

[0132] In block 730, terminal device 110 performs at least one of decryption or integrity verification on the MAC CE based on the configuration.

[0133] In some embodiments, the terminal device 110 may perform decryption on the MAC CE by determining a set of input parameters including at least one of a sequence number of the MAC CE, a logical channel identity of the MAC CE, a downlink direction, or a key for encryption, and performing decryption on the MAC CE based on the set of input parameters.

[0134] In some embodiments, the terminal device 110 may perform integrity verification on the MAC CE by determining a set of input parameters including at least one of a sequence number of the MAC CE, an LCID of the MAC CE, a downlink direction, or a key for integrity protection, and performing integrity verification on the MAC CE based on the set of input parameters.

[0135] In some embodiments, if an additional MAC CE is to be transmitted, terminal device 110 may perform at least one of ciphering or integrity protection to generate the additional MAC CE to be transmitted based on the configuration. In some embodiments, the additional MAC CE may indicate completion of the LTM cell switch. In some embodiments, the additional MAC CE includes at least one of a sequence number or a MAC-I of the additional MAC CE.

[0136] In some embodiments, the terminal device 110 may perform encryption by determining a set of input parameters including at least one of a sequence number of the further MAC CE, a logical channel identity of the further MAC CE, an uplink direction, or a key for encryption, and performing encryption based on the set of input parameters.

[0137] In some embodiments, the terminal device 110 may perform the integrity protection by determining a set of input parameters including at least one of a sequence number of the further MAC CE, a logical channel identity of the further MAC CE, an uplink direction, or a key for integrity protection, and performing the integrity protection based on the set of input parameters.

[0138] The method 700 allows for MAC layer security.

[0139] 8 illustrates another exemplary communication method 800 implemented in a terminal device according to some embodiments of the present disclosure. For example, method 800 may be performed in terminal device 110 as shown in FIG. 1A. For purposes of discussion, method 800 is described below with reference to FIG. 1A. It should be understood that method 800 may include additional blocks not shown and / or omit some blocks shown, and that the scope of the present disclosure is not limited in this respect.

[0140] At block 810, the terminal device 110 receives a first MAC CE from the network device 120 indicating a cell switch to a target candidate cell.

[0141] In block 820, the terminal device 110 starts a timer for detecting failure in cell switching.

[0142] In block 830, the terminal device 110 determines that the cell switch RA procedure is to be skipped.

[0143] In block 840, terminal device 110 receives a first indication from network device 120 that completion of the cell switch has been received.

[0144] In some embodiments, if the terminal device 110 receives a first PDCCH transmission addressed to the identity of the terminal device 110 and the first PDCCH transmission includes a DL allocation, the terminal device 110 may determine that a first indication has been received.

[0145] In some embodiments, if the terminal device 110 receives a second PDCCH transmission addressed to the identity of the terminal device 110 and the second PDCCH transmission includes an UL grant, the terminal device 110 may determine that the first indication has been received.

[0146] In some embodiments, if the terminal device 110 receives a third PDCCH transmission addressed to the identity of the terminal device 110 and the third PDCCH transmission includes an UL grant for the transmission to be performed, the terminal device 110 may determine that the first indication has been received.

[0147] In some embodiments, if the terminal device 110 receives a fourth PDCCH transmission addressed to the identity of the terminal device 110, the fourth PDCCH transmission includes an UL grant for the first transmission to be performed, and the first transmission has the same HARQ process as the second transmission to be performed, the terminal device 110 may determine that the first indication has been received.

[0148] In some embodiments, terminal device 110 may determine that the first indication is received if terminal device 110 receives a second MAC CE in the PDSCH indicated by the fifth PDCCH transmission addressed to the identity of terminal device 110. In some embodiments, the second MAC CE may be at least one of a MAC CE different from the first MAC CE, a MAC CE with a fixed size of zero bits, or a UE contention resolution identity MAC CE.

[0149] In block 850, the terminal device 110 stops the timer, i.e., upon receiving the first indication, the terminal device 110 stops the timer.

[0150] In some embodiments, the terminal device 110 may transmit a further second indication of the completion of the cell switch to the network device 120 by at least one of an UL grant configured for the first MAC CE, an UL grant configured for a configuration associated with the target candidate cell, and an UL grant received from a PDCCH transmission of the target candidate cell addressed to the identity of the terminal device 110.

[0151] In some embodiments, the terminal device 110 may transmit a further second indication by a third MAC CE of a priority higher than the priority of the data from the logical channel and lower than the priority of the data from the UL-CCCH.

[0152] In some embodiments, if a TA value is provided in the first MAC CE, the terminal device 110 may determine that the random access procedure for cell switching is skipped. In some embodiments, if a time alignment timer is running for the TAG to which the target candidate cell belongs, the terminal device 110 may determine that the RA procedure for cell switching is skipped.

[0153] The method 800 allows completion of a RACH-less LTM to be indicated to a terminal device.

[0154] 9 illustrates yet another exemplary communication method 900 implemented in a terminal device, according to some embodiments of the present disclosure. For example, method 900 may be performed in terminal device 110, such as that shown in FIG. 1A. For purposes of discussion, method 900 is described below with reference to FIG. 1A. It should be understood that method 900 may include additional blocks not shown and / or omit some blocks shown, and that the scope of the present disclosure is not limited in this respect.

[0155] In block 910, the terminal device 110 receives a MAC CE from the network device 120 indicating a cell switch.

[0156] In block 920, terminal device 110 determines that a partial MAC reset procedure is to be performed.

[0157] In block 920, terminal device 110 enables periodic PHR.

[0158] In some embodiments, terminal device 110 may enable periodic PHR by at least one of starting or restarting a timer for periodic PHR or maintaining the timer during a partial MAC reset procedure.

[0159] In this way, periodic PHRs can be triggered in case of a partial MAC reset during LTM.

[0160] 10 illustrates yet another exemplary communication method 1000 implemented in a terminal device, according to some embodiments of the present disclosure. For example, method 1000 may be performed in terminal device 110 as shown in FIG. 1A. For purposes of discussion, method 1000 is described below with reference to FIG. 1A. It should be understood that method 1000 may include additional blocks not shown and / or omit some blocks shown, and that the scope of the present disclosure is not limited in this respect.

[0161] In block 1010, the terminal device 110 receives a MAC CE from the network device 120 indicating a cell switch.

[0162] In block 1020, the terminal device 110 performs SDU discard of the SRB with the PDCP entity of the network device 120.

[0163] In some embodiments, when a MAC CE is received, terminal device 110 may indicate a cell switch from the terminal device's MAC entity to the terminal device's RRC entity, and may indicate an SRB SDU discard from the RRC entity to the PDCP entity.

[0164] In some embodiments, upon receiving the MAC CE, terminal device 110 may indicate SDU discard of the SRB from the MAC entity of terminal device 110 to the PDCP entity.

[0165] In this way, PDCP SDU discarding for SRBs can be triggered during LTM without RRC configuration for PDCP SDU discarding.

[0166] It should be understood that the operations of methods 700-1000 correspond to those described in connection with Figures 2-6, and therefore other details will not be repeated here for the sake of brevity. Exemplary implementations of devices and apparatuses

[0167] 11 is a schematic block diagram of an apparatus 1100 suitable for implementing embodiments of the present disclosure. Apparatus 1100 may be considered another exemplary implementation of terminal device 110 or network device 120 as shown in FIG. 1A. Thus, apparatus 1100 may be implemented in, or at least as part of, terminal device 110 or network device 120.

[0168] As shown, the apparatus 1100 comprises a processor 1110, a memory 1120 coupled to the processor 1110, a suitable transmitter (TX) and receiver (RX) 1140 coupled to the processor 1110, and a communication interface coupled to the TX / RX 1140. The memory 1110 stores at least a portion of a program 1130. The TX / RX 1140 is for bidirectional communication. The TX / RX 1140 has at least one antenna to facilitate communication, although in practice the access nodes described herein may have multiple antennas. The communication interface may represent any interface required for communication with other network elements, for example, an X2 / Xn interface for bidirectional communication between eNBs / gNBs, an S1 / NG interface for communication between a Mobility Management Entity (MME) / Access and Mobility Management Function (AMF) / SGW / UPF and an eNB / gNB, an Un interface for communication between an eNB / gNB and a relay node (RN), or a Uu interface for communication between an eNB / gNB and a terminal device.

[0169] The program 1130 is assumed to include program instructions that, when executed by an associated processor 1110, enable the device 1100 to operate in accordance with embodiments of the present disclosure, as discussed herein with reference to FIGS. 1A-10. The embodiments herein may be implemented by computer software, hardware, or a combination of software and hardware executable by the processor 1110 of the device 1100. The processor 1110 may be configured to implement various embodiments of the present disclosure. Additionally, the combination of the processor 1110 and the memory 1120 may constitute a processing means 1150 suitable for implementing various embodiments of the present disclosure.

[0170] The memory 1120 may be of any type suitable for the local technology network and may be implemented using any suitable data storage technology (e.g., but not limited to, computer-readable non-transitory storage media, semiconductor-based storage devices, magnetic storage devices and systems, optical storage devices and systems, fixed and removable memory, etc.). Although only one memory 1120 is shown in the device 1100, the device 1100 may include multiple physically distinct memory modules. The processor 1110 may be of any type suitable for the local technology network and may include, by way of example and not limitation, one or more of a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor configuration. The device 1100 may have multiple processors, e.g., application-specific integrated circuit chips time-slaved to a clock synchronized with a master processor.

[0171] In some embodiments, the terminal device includes circuitry configured to receive MAC layer security settings from the network device and, upon determining that a MAC CE is received, perform at least one of decryption or integrity verification on the MAC CE based on the settings.

[0172] In some embodiments, the terminal device includes circuitry configured to start a timer for detecting a failure in cell switching in accordance with a determination that a first MAC CE indicating a cell switching to a target candidate cell is received from the network device, determine that a random access procedure for cell switching is skipped, and stop the timer in accordance with a determination that a first indication of completion of the cell switching is received from the network device.

[0173] In some embodiments, the terminal device includes circuitry configured to receive a MAC CE from the network device indicating a cell switch and enable periodic PHR pursuant to a determination that a partial MAC reset procedure is to be performed.

[0174] In some embodiments, the terminal device includes circuitry configured to receive a MAC CE indicating a cell switch from the network device and to perform SDU discard of the SRB by a PDCP entity of the network device.

[0175] As used herein, the term "circuit" may refer to a hardware circuit and / or a combination of a hardware circuit and software. For example, a circuit may be a combination of analog and / or digital hardware circuitry with software / firmware. As a further example, a circuit may be any portion of a hardware processor with software, such as a digital signal processor, software, and memory that cooperate to perform various functions on a device, such as a terminal device or network device. In yet another example, a circuit may be a hardware circuit and / or processor, such as a microprocessor or portion of a microprocessor, that requires software / firmware for operation but the software may be absent when not required for operation. As used herein, the term circuit also encompasses a simple hardware circuit or processor, or portion of a hardware circuit or processor, and its (or their) accompanying software and / or firmware implementation.

[0176] In summary, the embodiments of the present disclosure can provide the following solutions:

[0177] In some embodiments, the terminal device includes a processor configured to cause the terminal device to receive medium access control (MAC) layer security configuration from the network device and, upon determining that a medium access control control element (MAC CE) is received, perform at least one of decryption or integrity verification on the MAC CE based on the configuration.

[0178] In some embodiments, the settings include at least one of a first setting for encryption or a second setting for integrity protection.

[0179] In some embodiments, the first configuration includes at least one of an indication of whether encryption is enabled or an encryption algorithm.

[0180] In some embodiments, the second configuration includes at least one of an indication of whether integrity protection is enabled or an integrity protection algorithm.

[0181] In some embodiments, the MAC CE indicates layer 1 or layer 2 triggered mobility.

[0182] In some embodiments, the terminal device performs decryption on the MAC CE by determining a set of input parameters including at least one of a sequence number of the MAC CE, a logical channel identity of the MAC CE, a downlink direction, or a key for encryption, and performing decryption on the MAC CE based on the set of input parameters.

[0183] In some embodiments, the terminal device performs integrity verification on the MAC CE by determining a set of input parameters including at least one of a sequence number of the MAC CE, a logical channel identity of the MAC CE, a downlink direction, or a key for integrity protection, and performing integrity verification on the MAC CE based on the set of input parameters.

[0184] In some embodiments, following a determination that a further medium access control (MAC CE) is to be transmitted, the terminal device further performs, based on the configuration, at least one of encryption or integrity protection to generate the further MAC CE to be transmitted.

[0185] In some embodiments, the terminal device performs the encryption by determining a set of input parameters including at least one of a sequence number of the further MAC CE, a logical channel identity of the further MAC CE, an uplink direction, or a key for encryption, and performing the encryption based on the set of input parameters.

[0186] In some embodiments, the terminal device performs the integrity protection by determining a set of input parameters including at least one of a sequence number of the further MAC CE, a logical channel identity of the further MAC CE, an uplink direction, or a key for integrity protection, and performing the integrity protection based on the set of input parameters.

[0187] In some embodiments, the further MAC CE indicates completion of a layer 1 or layer 2 triggered mobility cell switch.

[0188] In some embodiments, the further MAC CE includes at least one of a sequence number of the further MAC CE or a message authentication code for integrity (MAC-I).

[0189] In some embodiments, the MAC CE includes at least one of a sequence number of the MAC CE or a message authentication code for integrity (MAC-I).

[0190] In another solution, the terminal device includes a processor configured to cause the terminal device to start a timer for detecting a failure in cell switching in accordance with a determination that a first medium access control (MAC CE) indicating a cell switching to a target candidate cell is received from the network device, determine that a random access procedure for cell switching is skipped, and stop the timer in accordance with a determination that a first indication of completion of the cell switching is received from the network device.

[0191] In some embodiments, the terminal device receives the first indication by at least one of receiving a first physical downlink control channel (PDCCH) transmission addressed to the terminal device identity including a downlink assignment, receiving a second PDCCH transmission addressed to the terminal device identity including an uplink grant, receiving a third PDCCH transmission addressed to the terminal device identity including an uplink grant for the performed transmission, receiving a fourth PDCCH transmission addressed to the terminal device identity including an uplink grant for the performed first transmission having the same hybrid automatic repeat request (HARQ) process as the performed second transmission, or receiving a second MAC CE on a physical downlink shared channel (PDSCH) indicated by a fifth PDCCH transmission addressed to the terminal device identity.

[0192] In some embodiments, the second MAC CE is at least one of a MAC CE different from the first MAC CE, a MAC CE with a fixed size of zero bits, or a user equipment (UE) contention resolution identity MAC CE.

[0193] In some embodiments, the terminal device further transmits a second indication of completion of the cell switch to the network device via at least one of an uplink grant configured for the first MAC CE, an uplink grant configured for a configuration associated with the target candidate cell, or an uplink grant received from a physical downlink control channel (PDCCH) transmission of the target candidate cell addressed to an identity of the terminal device.

[0194] In some embodiments, the terminal device transmits the second indication by means of a third MAC CE having a priority higher than the priority of data from the logical channel and lower than the priority of data from the uplink common control channel.

[0195] In some embodiments, the terminal device determines that the random access procedure for cell switching is skipped based on at least one of determining that a TA value is provided in the first MAC CE or determining that a time alignment timer is running for the timing advance group to which the target candidate cell belongs.

[0196] In another solution, the terminal device includes a processor configured to cause the terminal device to receive a medium access control (MAC CE) from a network device indicating a cell switch, and enable periodic power headroom reports (PHR) in accordance with a determination that a partial medium access control (MAC) reset procedure is to be performed.

[0197] In some embodiments, the terminal device enables periodic PHR by at least one of starting or restarting a timer for periodic PHR or maintaining the timer during a partial MAC reset procedure.

[0198] In another solution, the terminal device includes a processor configured to cause the terminal device to receive a medium access control element (MAC CE) from the network device indicating a cell switch, and perform a service data unit (SDU) discard of a signal radio bearer (SRB) by a packet data convergence protocol (PDCP) entity of the network device.

[0199] In some embodiments, following a determination that a MAC CE has been received, the terminal device performs an SDU discard procedure by indicating a cell switch from the medium access control (MAC) entity of the terminal device to a radio resource control (RRC) entity of the terminal device, and indicating SDU discard of the SRB from the RRC entity to a PDCP entity.

[0200] In some embodiments, following a determination that a MAC CE has been received, the terminal device performs an SDU discard procedure by indicating SDU discard of the SRB from the medium access control (MAC) entity of the terminal device to the PDCP entity.

[0201] In another solution, a communication method includes, in a terminal device, receiving medium access control (MAC) layer security configuration from a network device, and, upon determining that a medium access control control element (MAC CE) is received, performing at least one of decryption or integrity verification on the MAC CE based on the configuration.

[0202] In another solution, a communication method includes starting a timer in a terminal device for detecting a failure in cell switching in accordance with a determination that a first medium access control element (MAC CE) indicating a cell switching to a target candidate cell is received from a network device, determining that a random access procedure for cell switching is skipped, and stopping the timer in accordance with a determination that a first indication of completion of the cell switching is received from the network device.

[0203] In another solution, a communication method includes receiving, in a terminal device, a medium access control control element (MAC CE) indicating a cell switch, and enabling periodic power headroom reporting (PHR) according to a determination that a partial medium access control (MAC) reset procedure is performed.

[0204] In another solution, a communication method includes, in a terminal device, receiving a medium access control element (MAC CE) from a network device indicating a cell switch, and performing a service data unit (SDU) discard of a signal radio bearer (SRB) by a packet data convergence protocol (PDCP) entity of the network device.

[0205] Overall, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic, or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software executable by a controller, microprocessor, or other computing device. While various aspects of embodiments of the present disclosure have been illustrated and described using block diagrams, flowcharts, or other pictorial representations, it should be understood that the blocks, devices, systems, techniques, or methods described herein may be implemented, by way of non-limiting example, in hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing device, or any combination thereof.

[0206] The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as instructions included in program modules, that execute within a device on a target real or virtual processor to perform the processes or methods described above with reference to Figures 2-7. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular abstract data types. In various embodiments, the functionality of the program modules may be combined or split between program modules as desired. The machine-executable instructions of the program modules may be executed within local or distributed devices. In a distributed device, program modules may be located in both local and remote storage media.

[0207] Program code for carrying out the methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device, and when executed by the processor or controller, cause the program code to implement the functions / acts specified in the flowcharts and / or block diagrams. The program code may run entirely on the machine, partially on the machine, as a separate software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0208] The above-described program code may be embodied on a machine-readable medium, which may be any tangible medium that can contain or store a program used by or associated with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the aforementioned media. More specific examples of a machine-readable storage medium may include an electrical connection having one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0209] It should be noted that, although operations have been described in a particular order, it should not be understood that performing such operations in the particular order shown, or in any sequential order, or performing all of the operations described, is required to achieve desirable results. In some cases, multitasking and parallel processing may be advantageous. Similarly, while several specific implementation details are included in the above discussion, these should not be construed as limitations on the scope of the disclosure, but rather as descriptions of features that may be specific to particular embodiments. Some features that are described in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable subcombination.

[0210] Although the present disclosure has been described in language specific to structural features and / or methodological acts, it should be understood that the present disclosure, as defined in the appended claims, is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A terminal device including a processor, The processor causes the terminal device to receiving a medium access control (MAC) layer security configuration from a network device; pursuant to determining that a medium access control control element (MAC CE) is received, performing at least one of decryption or integrity verification on the MAC CE based on the configuration; and It is configured to Terminal device.

2. The settings include: A first setting for encryption, or Secondary setting for integrity protection At least one of The terminal device according to claim 1 .

3. The first setting includes: an indication of whether the encryption is valid; or Encryption algorithm At least one of The terminal device according to claim 2 .

4. The second setting includes: an indication of whether said integrity protection is enabled; or Integrity Protection Algorithm At least one of The terminal device according to claim 2 .

5. The MAC CE indicates mobility triggered by Layer 1 or Layer 2. The terminal device according to claim 1 .

6. determining a set of input parameters including at least one of a sequence number of the MAC CE, a logical channel identity of the MAC CE, a downlink direction, or a key for ciphering; performing the decryption on the MAC CE based on the set of input parameters; performing the decryption on the MAC CE by The terminal device according to claim 1 .

7. determining a set of input parameters including at least one of a sequence number of the MAC CE, a logical channel identity of the MAC CE, a downlink direction, or a key for integrity protection; performing the integrity verification on the MAC CE based on the set of input parameters; performing the integrity verification on the MAC CE by The terminal device according to claim 1 .

8. and, upon determining that a further medium access control element (MAC CE) is to be transmitted, further performing at least one of encryption or integrity protection to generate the further MAC CE to be transmitted based on the configuration. The terminal device according to claim 1 .

9. determining a set of input parameters comprising at least one of a sequence number of the further MAC CE, a logical channel identity of the further MAC CE, an uplink direction, or a key for ciphering; performing the encryption based on the set of input parameters; performing the encryption by The terminal device according to claim 8.

10. determining a set of input parameters comprising at least one of a sequence number of the further MAC CE, a logical channel identity of the further MAC CE, an uplink direction, or a key for integrity protection; performing the integrity protection based on the set of input parameters; performing said integrity protection by The terminal device according to claim 8.

11. the further MAC CE indicating completion of a Layer 1 or Layer 2 triggered mobility cell switch; The terminal device according to claim 8.

12. the further MAC CE includes at least one of a sequence number of the further MAC CE or a message authentication code for integrity (MAC-I); The terminal device according to claim 8.

13. The MAC CE includes at least one of a sequence number of the MAC CE or a message authentication code for integrity (MAC-I); The terminal device according to claim 1 .

14. A terminal device including a processor, The processor causes the terminal device to In response to determining that a first medium access control (MAC CE) indicating a cell switch to a target candidate cell is received from a network device, starting a timer for detecting a failure in the cell switch; determining that the cell switching random access procedure is skipped; and stopping the timer in response to a determination that a first indication of completion of the cell switch is received from the network device; and It is configured to Terminal device.

15. receiving a first physical downlink control channel (PDCCH) transmission addressed to an identity of the terminal device, the PDCCH transmission including a downlink assignment; receiving a second PDCCH transmission addressed to the identity of the terminal device, the second PDCCH transmission including an uplink grant; receiving a third PDCCH transmission addressed to the identity of the terminal device, the third PDCCH transmission including an uplink grant for the transmission to be performed; receiving a fourth PDCCH transmission addressed to the identity of the terminal device, the fourth PDCCH transmission including an uplink grant for a first transmission performed, the first transmission having the same hybrid automatic repeat request (HARQ) process as a second transmission performed; or receiving a second MAC CE on a physical downlink shared channel (PDSCH) indicated by a fifth PDCCH transmission addressed to the identity of the terminal device; receiving the first indication by at least one of The terminal device according to claim 14.

16. The second MAC CE a MAC CE different from the first MAC CE; a MAC CE with a fixed size of zero bits, or User Equipment (UE) Contention Resolution Identity MAC CE At least one of The terminal device according to claim 15.

17. an uplink grant configured in the first MAC CE; an uplink grant configured in a configuration associated with the target candidate cell; or an uplink grant received from a physical downlink control channel (PDCCH) transmission of the target candidate cell addressed to the identity of the terminal device; and further transmitting a second indication of completion of the cell switch to the network device by at least one of The terminal device according to claim 14.

18. transmitting the second indication by a third MAC CE having a priority higher than that of data from a logical channel and lower than that of data from an uplink common control channel; The terminal device according to claim 17.

19. A terminal device including a processor, The processor causes the terminal device to receiving a medium access control element (MAC CE) from a network device indicating a cell switch; pursuant to a determination that a partial medium access control (MAC) reset procedure is performed, enabling periodic power headroom reports (PHR); and It is configured to Terminal device.

20. starting or restarting a timer for the periodic PHR; or Maintaining the timer during the partial MAC reset procedure. enabling the periodic PHR by at least one of 20. The terminal device according to claim 19.

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