Method and apparatus for random access during LTM cell switch

Abstract

Provided in the embodiments of the present application are a method and apparatus for random access during LTM cell switch. The method for random access during LTM cell switch comprises: when a terminal device is configured with 2-step random access resources, using a 2-step random access type for the random access process of the terminal device; alternatively, when the terminal device is configured with the 2-step random access resources, using a 4-step random access type for the random access process of the terminal device.

Description

Random access method and device in LTM cell change Technical Field

[0001] The embodiments of the present application relate to the field of communications. Background Art

[0002] The random access procedure can be triggered by the following events:

[0003] Initial access from RRC_IDLE;

[0004] RRC connection reestablishment process;

[0005] During RRC_CONNECTED or RRC_INACTIVE, while the SDT (Small Data Transmission) process is in progress, downlink (DL) or uplink (UL) data arrives, and the UL synchronization state is "asynchronous";

[0006] During RRC_CONNECTED or RRC_INACTIVE, while the SDT process is in progress and UL data arrives, when there are no available PUCCH resources for the SR (Scheduling Request);

[0007] Handover

[0008] SR failed;

[0009] Explicit request from RRC during synchronous reconfiguration;

[0010] RRC connection recovery procedure from RRC_INACTIVE;

[0011] To establish time synchronization of primary or secondary TAG;

[0012] Other SI (system information) requests;

[0013] Beam failure recovery;

[0014] Continuous UL LBT failure on special cells;

[0015] SDT in RRC_INACTIVE;

[0016] Positioning during random access procedure is required during RRC_CONNECTED, such as when timing advance is required for UE positioning;

[0017] Early UL synchronization with LTM candidate cells;

[0018] RACH-based LTM cell change (cell switch).

[0019] There are two types of random access procedures: 4-step random access (RA) using MSG1 and 2-step random access (RA) using MSGA. Both procedures support contention-based random access (CBRA) and contention-free random access (CFRA).

[0020] FIG1 is a schematic diagram of information exchange between 4-step random access and 2-step random access.

[0021] In the 4-step RA type random access procedure, MSG1 includes a preamble on the PRACH (Physical Random Access Channel). After MSG1 is transmitted, the UE listens for a response from the network within a configured window.

[0022] For CFRA, the network allocates a dedicated preamble for MSG1 transmission, and once the random access response is received from the network, the UE ends the random access procedure (as shown in (c) in Figure 1);

[0023] For CBRA, upon receiving a random access response, the UE sends MSG3 using the UL grant scheduled in the response and monitors contention resolution (as shown in (a) in Figure 1 ). If contention resolution is unsuccessful after MSG3 transmission / retransmission, the UE returns to MSG1 transmission.

[0024] In the 2-step RA type random access procedure, the MSGA consists of a preamble on the PRACH and a data (payload) on the PUSCH. After the MSGA is transmitted, the UE listens for a response from the network within a configured window;

[0025] For CFRA, dedicated preamble and PUSCH resources for MSGA transmission are configured, and once the network response is received, the UE ends the random access procedure (as shown in (d) in Figure 1);

[0026] For CBFA, if the contention resolution is successful when receiving the network response, the UE ends the random access procedure (as shown in (b) in Figure 1);

[0027] In addition, as shown in (e) of FIG1 , the 4-step RA type random access procedure also supports CFRA without network response.

[0028] Figure 2 is a diagram illustrating the steps / functions implemented by the UE's MAC layer to support a 4-step RA type random access procedure, wherein the preamble transmission process includes the transmission of MSG1, and the RAR reception process includes the reception of MSG2.

[0029] As shown in Figure 2, when the random access procedure is initialized, the UE selects the random access type based on the network configuration:

[0030] When CFRA resources are not configured, the UE uses the RSRP threshold to select between the 2-step RA type and the 4-step RA type;

[0031] When CFRA resources are configured for 4-step RA type, the UE performs 4-step RA type random access;

[0032] When CFRA resources are configured for the 2-step RA type, the UE performs random access of the 2-step RA type.

[0033] In addition, the network will not configure both 2-step RA and 4-step RA CFRA resources for a BWP. 2-step RA CFRA resources only support handover.

[0034] It should be noted that the above introduction to the technical background is merely intended to provide a clear and complete description of the technical solutions of this application and facilitate understanding by those skilled in the art. Simply because these solutions are described in the background technology section of this application, it should not be assumed that the above technical solutions are well known to those skilled in the art.

[0035] Summary of the Invention

[0036] During Layer 1 / Layer 2 triggered Mobility (LTM), the network sends a Cell Switch Command (CSC) to the terminal equipment (UE) via an LTM CSC MAC CE. Figure 3 illustrates the format of an LTM CSC MAC CE. As shown in Figure 3, the LTM CSC MAC CE indicates the TCI state and the Timing Advance Command.

[0037] In the LTM CSC MAC CE shown in Figure 3, the specific meanings of the various fields are as follows:

[0038] C: This field indicates the presence of the contention-free Random Access Resources field. If the value of this field is set to 1, the following fields are present: including the Random Access Preamble index field, S / U field, SS / PBCH index field, PRACH Mask index field, and Repetition number field. If the value of this field is set to 0, the Random Access Preamble index field, SS / PBCH index field, PRACH Mask index field, and Repetition number field are absent, and the S / U field is considered as a Reserved field.

[0039] S / U: This field indicates which UL carrier sends the PRACH of contention-free Random Access Resources. If the value of this field is set to 1, SUL is used; otherwise, NUL is used. The length of this field is 1 bit;

[0040] Random Access Preamble Index: This field indicates the Random Access Preamble index of the contention-free Random Access Resources. This field should not be set to 0b000000. The length of this field is 6 bits;

[0041] SS / PBCH index: For PRACH transmission of contention-free Random Access Resources, this field indicates the SS / PBCH that will be used to determine the RACH occasion. The field length is 6 bits;

[0042] PRACH Mask index: For PRACH transmission of this contention-free Random Access Resources, this field indicates the RACH occasion(s) associated with the SS / PBCH indicated by "SS / PBCH index". It indicates a subset of RACH occasion(s) from the rach-ConfigDedicated for the UL carrier (indicated by S / U field), if provided; otherwise, it indicates a subset of RACH occasion(s) from the rach-ConfigCommon for the UL carrier (indicated by S / U field) in the UL BWP configuration of firstActiveUplinkBWP-Id as specified in TS 38.331[5]. This field is 4 bits long.

[0043] Currently, the network uses IE RACH-ConfigDedicated and IE RACH-ConfigCommon to configure random access resources for UE for CFRA and 4-step CBRA respectively, as follows.

[0044] IE RACH ConfigDedicated is used to specify dedicated random access parameters:

[0045] [Corrected 01.07.2024 according to Rule 26] RACH-ConfigDedicated information element

[0046] Figure 4 illustrates the LTM cell change process on the UE side. As shown in Figure 4, according to current standards, upon receiving the LTM CSC MAC CE, the LTM cell change process on the UE side proceeds as follows: Upon receiving the LTM CSC MAC CE, the MAC layer indicates the target configuration ID to the upper layer (e.g., the RRC layer); based on this configuration ID, the RRC layer performs LTM execution and applies the configuration corresponding to this configuration ID. The RRC layer instructs the lower layer (e.g., the MAC layer) to perform a MAC reset; after completing the MAC reset as requested by the upper layer (e.g., the RRC layer), the terminal device processes the remaining fields in the LTM CSC MAC CE, including fields related to the TCI status, TA, and RA.

[0047] The terminal processes other fields in the LTM CSC MAC CE, including:

[0048] If the TAC value is not set to FFF, the MAC layer will:

[0049] Processing of received TAC;

[0050] The RACH-less LTM cell change is considered to be ongoing.

[0051] If the MAC entity is associated with an SCG:

[0052] Indicates to upper layers that the random access procedure is skipped for this LTM cell change.

[0053] Otherwise, if TA measurement is configured and the UE has successfully measured the TA of the indicated LTM target, the MAC layer shall:

[0054] TA that processes the measurements;

[0055] The RACH-less LTM cell change is considered to be ongoing.

[0056] If the MAC entity is associated with an SCG:

[0057] Indicates to upper layers that the random access procedure is skipped for this LTM cell change.

[0058] If TCI status information is included, the MAC layer shall:

[0059] The SSB corresponding to the indicated TCI state is considered as the SSB selected for the configured uplink grant for the initial uplink transmission on the candidate cell in the RACH-less LTM cell change;

[0060] Indicates to lower layers the information related to the TCI status information in the LTM cell change command MAC CE.

[0061] The inventors found that there are the following problems:

[0062] As described above, if the TAC value is not set to FFF or if TA measurement is configured and the UE has successfully measured the TA of the indicated LTM target, a RACH-less LTM cell change is performed; otherwise, an LTM cell change triggers a random access procedure.

[0063] Currently, both CFRA and CBRA support 2-step and 4-step RA types. The UE determines the RA type based on the network configuration. According to the current mechanism, if the random access procedure is triggered by an LTM cell change and CFRA resources are not provided in the LTM CSC MAC CE, the UE will perform a 4-step RA type random access procedure. This means that the UE may use 2-step CFRA resources for 4-step RA, which is not the expected UE behavior and violates the basic principle: when CFRA resources are configured for 2-step RA, the UE performs 2-step RA type random access.

[0064] In addition, according to the field description for the LTM CSC MAC CE recorded above, for the PRACH transmission of the contention-free Random Access Resources, the PRACH Mask index field indicates the SS / PBCH associated RACH occasion(s) indicated by the "SS / PBCH index" field, which indicates a subset of RACH occasion(s) from the RACH-ConfigDedicated for the UL carrier (indicated by S / U field), if provided; otherwise, it indicates a subset of RACH occasion(s) from the rach-ConfigCommon for the UL carrier (indicated by S / U field) in the UL BWP configuration of firstActiveUplinkBWP-Id.

[0065] According to the above description, IErach-ConfigCommon is used to configure resources for 4-step RA. Therefore, when referencing RACH occasions in rach-ConfigCommon, the CFRA resources indicated by the MAC CE are a subset of the cell-shared random access resources configured for 4-step RA. However, IErach-Config Dedicated can be used to configure resources for either 4-step RA or 2-step RA. Therefore, when referencing RACH occasions in RACH-ConfigDedicated, it is unclear whether the CFRA resources indicated by the MAC CE are a subset of UE-specific random access resources configured for 4-step RA or 2-step RA. This can cause inconsistencies between networks and terminals, as well as uncertainty in implementation between different terminal manufacturers, thereby increasing testing costs.

[0066] Furthermore, as stated above, "If this field and cfra are absent, the UE performs contention-based random access," meaning that when both cfra and cfra-TwoStep are absent, the UE performs CBRA. This restriction applies to LTM, and even if the MAC CE provides CFRA resources, if neither cfra nor cfra-TwoStep is present, the UE must perform CBRA. This can introduce additional access latency during the LTM cell change process.

[0067] To address one or more of the above problems, embodiments of the present application provide a random access method and apparatus during LTM cell change.

[0068] According to a first aspect of an embodiment of the present application, a random access method in an LTM cell change is provided, the method comprising: when a terminal device is configured with a 2-step random access resource, the random access procedure of the terminal device uses a 2-step random access type; or, when a terminal device is configured with a 2-step random access resource, the random access procedure of the terminal device uses a 4-step random access type.

[0069] According to a second aspect of an embodiment of the present application, a random access method in an LTM cell change is provided, the method comprising: a network device configuring a 2-step random access resource to a terminal device, the 2-step random access resource cannot be used for LTM, or the network device does not configure a 2-step random access resource for an LTM cell change to the terminal device.

[0070] According to a third aspect of an embodiment of the present application, a random access method in an LTM cell change is provided, the method comprising: a terminal device receiving an LTM CSC MAC CE from a network device, wherein the CFRA resource indicated by the LTM CSC MAC CE is a 2-step random access resource, or the CFRA resource indicated by the LTM CSC MAC CE does not include a 2-step random access resource.

[0071] According to a fourth aspect of an embodiment of the present application, a random access method in an LTM cell change is provided, the method comprising: a network device sending an LTM CSC MAC CE to a terminal device, wherein the CFRA resource indicated by the LTM CSC MAC CE is a 2-step random access resource, or the CFRA resource indicated by the LTM CSC MAC CE does not include a 2-step random access resource.

[0072] According to a fifth aspect of an embodiment of the present application, a random access method in an LTM cell change is provided, the method comprising: a terminal device receiving a RACH-ConfigDedicated from a network device; when cfra and cfra-TwoStep do not exist in the RACH-ConfigDedicated and the random access procedure is not initiated for an LTM cell change, the terminal device performing CBRA; and / or, when cfra or cfra-TwoStep exists in the RACH-ConfigDedicated, the terminal device performing CFRA.

[0073] According to the sixth aspect of an embodiment of the present application, a random access device in an LTM cell change is provided, and the device is arranged in a terminal device, and the device includes: a first determination unit, which determines that the random access process of the terminal device uses a 2-step random access type when a 2-step random access resource is configured; or, a second determination unit, which determines that the random access process of the terminal device uses a 4-step random access type when a 2-step random access resource is configured.

[0074] According to the seventh aspect of the embodiment of the present application, a random access device in LTM cell change is provided, which is arranged in a network device, and the device includes: a configuration unit, which configures 2-step random access resources to the terminal device, and the 2-step random access resources cannot be used for LTM; or, it does not configure 2-step random access resources for LTM cell change to the terminal device.

[0075] According to an eighth aspect of an embodiment of the present application, a terminal device is provided, wherein the network device includes the apparatus according to the sixth aspect of an embodiment of the present application.

[0076] According to a ninth aspect of the embodiments of the present application, a network device is provided, comprising the apparatus according to the seventh aspect of the embodiments of the present application.

[0077] According to the tenth aspect of the embodiment of the present application, a communication system is provided, which includes the terminal device according to the eighth aspect of the embodiment of the present application and / or the network device according to the ninth aspect of the embodiment of the present application.

[0078] According to the eleventh aspect of the embodiment of the present application, a computer-readable program is provided, wherein when the program is executed in a random access device or terminal device in an LTM cell change, the program causes the random access device or terminal device in the LTM cell change to perform the random access method in the LTM cell change described in the first aspect of the embodiment of the present application.

[0079] According to the twelfth aspect of the embodiment of the present application, a storage medium storing a computer-readable program is provided, wherein the computer-readable program enables the random access device or terminal equipment in the LTM cell change to execute the random access method in the LTM cell change described in the first aspect of the embodiment of the present application.

[0080] According to the thirteenth aspect of the embodiment of the present application, a computer-readable program is provided, wherein when the program is executed in a random access device or network device in an LTM cell change, the program causes the random access device or network device in the LTM cell change to perform the random access method in the LTM cell change described in the second aspect of the embodiment of the present application.

[0081] According to the fourteenth aspect of the embodiment of the present application, a storage medium storing a computer-readable program is provided, wherein the computer-readable program enables the random access device or network equipment in the LTM cell change to execute the random access method in the LTM cell change described in the second aspect of the embodiment of the present application.

[0082] One of the beneficial effects of the embodiments of the present application is:

[0083] For LTM, if a terminal device is configured with 2-step random access resources, the terminal device's random access process uses the 2-step random access type, or the terminal device's random access process uses the 4-step random access type. This ensures that the terminal device performs the expected behavior, that is, the expected type of random access process, avoids different implementation methods among different vendors, and thus reduces deployment costs caused by testing.

[0084] In addition, the CFRA resources indicated by the LTM CSC MAC CE received by the terminal device from the network device are 2-step random access resources, or the CFRA resources indicated by the LTM CSC MAC CE do not include 2-step random access resources. This ensures that the network and the terminal have a consistent understanding of random access resources, eliminates implementation uncertainty among different terminal manufacturers, and reduces testing costs.

[0085] In addition, when the terminal device does not contain cfra or cfra-TwoStep in the RACH-ConfigDedicated received from the network device, and the random access procedure is not initiated for an LTM cell change, the terminal device performs CBRA; and / or when cfra or cfra-TwoStep is present in the RACH-ConfigDedicated, the terminal device performs CFRA. In this way, the correct type of random access procedure can be performed in a timely manner, avoiding unnecessary random access procedures and introducing additional access delays.

[0086] With reference to the following description and accompanying drawings, specific embodiments of the present application are disclosed in detail, indicating the manner in which the principles of the present application can be employed. It should be understood that the embodiments of the present application are not limited in scope. Within the spirit and scope of the appended claims, the embodiments of the present application include many variations, modifications and equivalents.

[0087] Features described and / or illustrated with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0088] It should be emphasized that the term "include / comprising" when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps or components. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] The elements and features described in one figure or one embodiment of the present application can be combined with the elements and features shown in one or more other figures or embodiments. In addition, in the accompanying drawings, similar reference numerals represent corresponding parts in several figures and can be used to indicate corresponding parts used in more than one embodiment.

[0090] FIG1 is a schematic diagram of information interaction between 4-step random access and 2-step random access;

[0091] FIG2 is a schematic diagram of steps / functions implemented by the MAC layer of a UE to support a 4-step RA type random access procedure;

[0092] FIG3 is a schematic diagram of the format of the LTM CSC MAC CE;

[0093] FIG4 is a schematic diagram of the behavior of LTM on the UE side;

[0094] FIG5 is a schematic diagram of a communication system according to an embodiment of the present application;

[0095] FIG6 is a schematic diagram of the overall process of LTM;

[0096] FIG7 is a schematic diagram of a random access method in an LTM cell change according to an embodiment of the present application;

[0097] FIG8 is another schematic diagram of a random access method in an LTM cell change according to an embodiment of the present application;

[0098] FIG9 is a schematic diagram of a random access method in an LTM cell change according to an embodiment of the present application;

[0099] FIG10 is another schematic diagram of a random access method in an LTM cell change according to an embodiment of the present application;

[0100] FIG11 is a schematic diagram of a random access method in an LTM cell change according to an embodiment of the present application;

[0101] FIG12 is a schematic diagram of a random access apparatus in an LTM cell change according to an embodiment of the present application;

[0102] FIG13 is a schematic diagram of a random access apparatus in an LTM cell change according to an embodiment of the present application;

[0103] 14 is a schematic block diagram of a system structure of a terminal device according to an embodiment of the present invention;

[0104] FIG15 is a schematic block diagram of the system structure of the network device according to an embodiment of the present application. DETAILED DESCRIPTION

[0105] The above and other features of the present application will become apparent through the following description with reference to the accompanying drawings. In the description and the accompanying drawings, specific embodiments of the present application are disclosed in detail, which illustrate some embodiments in which the principles of the present application can be adopted. It should be understood that the present application is not limited to the described embodiments. On the contrary, the present application includes all modifications, variations and equivalents that fall within the scope of the appended claims.

[0106] In the embodiments of the present application, the terms "first", "second", etc. are used to distinguish different elements from the name, but do not indicate the spatial arrangement or temporal order of these elements, and these elements should not be limited by these terms. The term "and / or" includes any one and all combinations of one or more of the associated listed terms. The terms "comprising", "including", "having", etc. refer to the presence of the stated features, elements, components or components, but do not exclude the presence or addition of one or more other features, elements, components or components.

[0107] In the embodiments of this application, the singular forms "a," "the," etc. include plural forms and should be broadly understood to mean "a" or "a type" rather than being limited to "one." Furthermore, the term "said" should be understood to include both singular and plural forms, unless the context clearly indicates otherwise. Furthermore, the term "according to" should be understood to mean "at least in part based on...", and the term "based on" should be understood to mean "at least in part based on...", unless the context clearly indicates otherwise.

[0108] In the embodiments of the present application, the term "communication network" or "wireless communication network" may refer to a network that complies with any of the following communication standards, such as Long Term Evolution (LTE), enhanced Long Term Evolution (LTE-A, LTE-Advanced), Wideband Code Division Multiple Access (WCDMA), High-Speed ​​Packet Access (HSPA), etc.

[0109] Furthermore, communication between devices in the communication system may be carried out according to communication protocols of any stage, for example, including but not limited to the following communication protocols: 1G (generation), 2G, 2.5G, 2.75G, 3G, 4G, 4.5G and 5G, New Radio (NR), future 6G, etc., and / or other communication protocols currently known or to be developed in the future.

[0110] In the embodiments of the present application, the term "network device" refers to, for example, a device in a communication system that connects a terminal device to the communication network and provides services to the terminal device. Network devices may include, but are not limited to, the following devices: base station (BS), access point (AP), transmission reception point (TRP), broadcast transmitter, mobile management entity (MME), gateway, server, radio network controller (RNC), base station controller (BSC), etc.

[0111] Among them, base stations may include but are not limited to: NodeB (NodeB or NB), evolved NodeB (eNodeB or eNB) and 5G base station (gNB), IAB host, etc., and may also include remote radio head (RRH, Remote Radio Head), remote radio unit (RRU, Remote Radio Unit), relay (relay) or low-power node (such as femeto, pico, etc.). The term "base station" can include some or all of their functions. Each base station can provide communication coverage for a specific geographical area. The term "cell" can refer to a base station and / or its coverage area, depending on the context in which the term is used.

[0112] In the embodiments of the present application, the term "user equipment" (UE) or "terminal equipment" (TE) refers to, for example, a device that accesses a communication network through a network device and receives network services. A terminal device can be fixed or mobile and may also be referred to as a mobile station (MS), a terminal, a subscriber station (SS), an access terminal (AT), a station, and so on.

[0113] Among them, terminal devices may include but are not limited to the following devices: cellular phones, personal digital assistants (PDAs), wireless modems, wireless communication devices, handheld devices, machine-type communication devices, laptop computers, cordless phones, smart phones, smart watches, digital cameras, etc.

[0114] For another example, in scenarios such as the Internet of Things (IoT), the terminal device can also be a machine or device for monitoring or measurement, including but not limited to: machine type communication (MTC) terminal, vehicle-mounted communication terminal, device-to-device (D2D) terminal, machine-to-machine (M2M) terminal, and so on.

[0115] In addition, the term "network side" or "network device side" refers to one side of the network, which can be a base station or one or more network devices as described above. The term "user side" or "terminal side" or "terminal device side" refers to the user or terminal side, which can be a UE or one or more terminal devices as described above. Unless otherwise specified herein, "device" can refer to either network equipment or terminal equipment.

[0116] The following describes the scenarios of the embodiments of the present application through examples, but the present application is not limited thereto.

[0117] FIG5 is a schematic diagram of a communication system according to an embodiment of the present application, schematically illustrating a situation using a terminal device and a network device as an example. As shown in FIG5 , a communication system 100 may include a network device 101 and a terminal device 102. For simplicity, FIG5 illustrates only one terminal device and one network device as an example, but the embodiments of the present application are not limited thereto.

[0118] In the embodiment of the present application, existing services or future services can be transmitted between the network device 101 and the terminal device 102. For example, these services may include, but are not limited to, enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra-reliable and low-latency communication (URLLC), etc.

[0119] The terminal device can perform an LTM cell change process, in which a network device (e.g., a gNB or gNB-DU) receives an L1 measurement report from the terminal device, and based on the L1 measurement report, the network device can change the serving cell of the terminal device through a cell change command (cell switch command) issued by a MAC CE.

[0120] For example, after an LTM cell handover, the terminal device does not update its security keys; subsequent LTM is supported. LTM supports intra-gNB-DU mobility and inter-gNB-DU mobility within a gNB-CU. LTM supports both intra-frequency and inter-frequency mobility, including mobility to an inter-frequency cell other than the current serving cell. LTM can support the following scenarios: PCell changes in non-CA and non-DC scenarios; PCell changes in CA scenarios; dual connectivity scenarios, MCG PCell changes, and SCGPSCell changes not involving a mobile node (i.e., PSCell changes within a SN).

[0121] Figure 6 is a schematic diagram of the overall process of LTM. As shown in Figure 6, the LTM process may include:

[0122] Step 1: The UE sends a MeasurementReport message to the gNB. The gNB decides to configure LTM and initiates candidate cell configuration.

[0123] Step 2: The gNB sends an RRCReconfiguration message to the UE, including the LTM candidate cell configuration of one or more candidate cells.

[0124] Step 3: The UE stores the LTM candidate cell configuration and sends an RRCReconfigurationComplete message to the gNB.

[0125] Step 4: Before receiving the cell change command, the UE performs DL synchronization of the candidate cell;

[0126] When UE-based TA measurement is configured, the UE obtains the TA value of the candidate cell through measurement. Otherwise, before receiving a cell change command, if the network requests that the UE perform early TA acquisition of the candidate cell, this can be accomplished by triggering a CFRA from the PDCCH order of the source cell and then sending a preamble to the indicated candidate cell. To minimize data interruption in the source cell caused by the CFRA to the candidate cell, the UE does not receive a random access response from the network to obtain the TA value. The TA value of the candidate cell is indicated in the cell handover command. The UE does not maintain a TA timer for the candidate cell and relies on the network to ensure TA validity.

[0127] Step 5: The UE performs L1 measurements on the configured candidate cells and sends an L1 measurement report to the gNB. L1 measurements should be performed whenever RRC reconfiguration (step 2) applies.

[0128] Step 6: The gNB decides to perform a cell change to the target cell and sends a MAC CE indicating a cell change with the candidate configuration index of the target cell. The UE switches to the target cell and applies the configuration indicated by the candidate configuration index.

[0129] Step 7: If the UE does not have a valid TA for the target cell, the UE performs a random access procedure to the target cell. If the LTM cell change command MAC CE includes CFRA information, the UE performs CFRA;

[0130] Step 8: The UE completes the LTM cell change procedure by sending an RRCReconfigurationComplete message to the target cell. If the UE has performed a random access procedure in step 7, the UE considers that the LTM cell change has been successfully completed when the random access procedure is successfully completed; for RACH-less LTM, the UE considers that the LTM cell change has been successfully completed when the UE determines that the network has successfully received its first UL data. The UE determines the successful reception of its first UL data by receiving a newly transmitted PDCCH addressed by the UE's C-RNTI in the target cell and after scheduling the first UL data. The PDCCH carries a DL assignment or a UL grant of the same HARQ process as the first UL data.

[0131] Subsequent LTM is performed by repeating the early synchronization, LTM cell change execution, and LTM cell change completion steps. After each LTM cell change is completed, the other LTM candidate cell configurations are not released. That is, using the LTM candidate cell configuration provided in step 2, steps 4-8 can be performed multiple times.

[0132] The above schematically illustrates the relevant contents of the embodiments of the present application, and the present application is further explained below.

[0133] Embodiments of the first aspect

[0134] An embodiment of the present application provides a random access method in LTM cell change, which is applied to a terminal device.

[0135] FIG7 is a schematic diagram of a random access method in an LTM cell change according to an embodiment of the present application. As shown in FIG7 , for LTM, the method includes:

[0136] 701: When the terminal device is configured with 2-step random access resources, the random access process of the terminal device uses the 2-step random access type; or,

[0137] 702: When the terminal device is configured with 2-step random access resources, the random access process of the terminal device uses a 4-step random access type.

[0138] It is worth noting that FIG. 7 above is merely a schematic illustration of an embodiment of the present application, and the present application is not limited thereto. For example, the execution order of the various operations may be appropriately adjusted, and other operations may be added or some operations may be reduced. Those skilled in the art may make appropriate modifications based on the above content, and are not limited to the description of FIG. 7 above.

[0139] In addition, operation 701 and operation 702 are alternative relationships, that is, the method includes operation 701, or the method includes operation 702.

[0140] In the embodiment of the present application, the random access process is a random access process in LTM;

[0141] For example, the random access procedure is initiated for LTM cell change, or the random access procedure is a random access procedure when LTM is in progress.

[0142] In some embodiments, the random access procedure is CFRA or CBRA.

[0143] In the embodiment of the present application, “2-step random access resources” may also be replaced by “resources configured for 2-step RA type random access”.

[0144] In operation 701, when a terminal device is configured with 2-step random access resources, the random access procedure of the terminal device uses a 2-step random access type.

[0145] In some embodiments, the configured 2-step random access resource includes at least one of the following:

[0146] A 2-step CFRA resource is configured. For example, RACH-ConfigDedicated includes cfra-TwoStep.

[0147] A 2-step CBRA resource is configured, for example, rach-ConfigCommonTwoStepRA is configured.

[0148] In some embodiments, the 2-step random access type is used, including:

[0149] During random access initialization, the MAC entity of the terminal device sets RA_TYPE to 2-stepRA.

[0150] In some embodiments, as shown in FIG7 , the method further includes:

[0151] 703: The terminal device receives the LTM CSC MAC CE from the network device.

[0152] The LTM CSC MAC CE does not explicitly indicate CFRA resources or explicitly indicates a subset of RACH occasion(s) from the RACH-ConfigDedicated for the UL carrier (indicated by S / U field).

[0153] Operation 703 is an optional operation and is indicated by a dotted box in FIG7 .

[0154] In some embodiments, for RACH-based LTM cell change, 2-step RA type CFRA is supported.

[0155] In some embodiments, the method further comprises:

[0156] 704: When the terminal device is configured with 4-step random access resources, the random access process of the terminal device uses the 4-step random access type.

[0157] Operation 704 is an optional operation and is indicated by a dotted box in FIG. 7 .

[0158] In some embodiments, the configured 4-step random access resource includes at least one of the following:

[0159] 4-step CFRA resources are configured. For example, RACH-ConfigDedicated includes cfra.

[0160] 4-step CBRA resources are configured, for example, rach-ConfigCommon is configured.

[0161] In some embodiments, for operation 702 and / or operation 704, using the 4-step random access type includes: during random access initialization, MAC sets RA_TYPE to 4-stepRA.

[0162] In some embodiments, the method further comprises:

[0163] 705: In the case where no 2-step random access resources and 4-step random access resources are configured for the terminal device, the random access process of the terminal device determines the random access type according to the reference signal received power (RSRP).

[0164] Operation 705 is an optional operation and is indicated by a dotted box in FIG7 .

[0165] In some embodiments, the random access resource is a CFRA resource, that is, the 2-step random access resource is a 2-step CFRA resource, and the 4-step random access resource is a 4-step CFRA resource.

[0166] The above operations 703-705 are optional operations, which are indicated by dashed boxes in Figure 7. In addition, there is no restriction on whether operations 703-705 are associated or in what order.

[0167] The following is a specific example of implementing the above embodiment:

[0168] In operation 702, when the terminal device is configured with 2-step random access resources, the random access procedure of the terminal device uses a 4-step random access type.

[0169] In some embodiments, the 2-step random access resource is not configured for LTM or cannot be used for LTM.

[0170] In some embodiments, the CFRA resource of the 2-step RA type in the 2-step random access resource is not configured for the LTM.

[0171] For example, if the random access is initiated for handover or synchronous reconfiguration, the network device may configure a 2-step RA type CFRA resource for the terminal device.

[0172] The following is a specific example of implementing the above embodiment:

[0173] For another example, if random access is initiated for LTM (cell change), the network device does not configure CFRA resources of the 2-step RA type for the terminal device, that is, it does not configure cfra-TwoStep or does not include cfra-TwoStep in the configuration. For example, if the IE RACH-ConfigDedicated is part of the RRCReconfiguration message in the IE LTM-Config, the network does not include the cfra-TwoStep field.

[0174] The following is a specific example of implementing the above embodiment:

[0175] In some embodiments, the 2-step RA type CFRA resource in the 2-step random access resource is not configured for the LTM, including: the network device only configures the 4-step RA type CFRA resource for the LTM.

[0176] In some embodiments, the CFRA resource of the 2-step RA type in the 2-step random access resource is not used for LTM cell change.

[0177] In some embodiments, as shown in FIG7 , the method further includes:

[0178] Operation 706: When CFRA resources of the 2-step RA type are configured for cell handover, the random access procedure of the terminal device uses the 2-step random access type, and the cell handover does not include an LTM cell change.

[0179] Operation 706 is an optional operation and is indicated by a dotted box in FIG. 7 .

[0180] The above embodiments are merely exemplary of the present invention, but the present invention is not limited thereto. Appropriate modifications may be made based on the above embodiments. For example, the above embodiments may be used alone, or one or more of the above embodiments may be combined.

[0181] Through the embodiments of the present application, for LTM, when a terminal device is configured with 2-step random access resources, the terminal device's random access process uses the 2-step random access type, or the terminal device's random access process uses the 4-step random access type. This ensures that the terminal device performs the expected behavior, i.e., performs the expected type of random access process, avoids different implementations by different manufacturers, and thus reduces deployment costs caused by testing.

[0182] Embodiments of the second aspect

[0183] The embodiment of the present application provides a random access method in LTM cell change, which is applied to a network device. The method corresponds to the method applied to a terminal device in the embodiment of the first aspect, and the relevant content can refer to the description of the embodiment of the first aspect.

[0184] FIG8 is another schematic diagram of a random access method in an LTM cell change according to an embodiment of the present application. As shown in FIG8 , the method includes:

[0185] 801: The network device configures 2-step random access resources for the terminal device. The 2-step random access resources cannot be used for LTM; or

[0186] 802: The network device does not configure 2-step random access resources for LTM cell change to the terminal device.

[0187] Operation 801 and operation 802 are performed alternatively.

[0188] In operation 801, the network device configures a 2-step random access resource for the terminal device. The 2-step random access resource cannot be used for LTM. For example, when the terminal device is configured with the 2-step random access resource, its random access process uses a 4-step random access type.

[0189] In operation 802 , the network device does not configure 2-step random access resources for LTM cell change to the terminal device, for example, the network device only configures 4-step RA type CFRA resources for LTM cell change.

[0190] It is worth noting that FIG8 above is merely a schematic illustration of an embodiment of the present application, and the present application is not limited thereto. For example, the execution order of the various operations may be appropriately adjusted, and other operations may be added or some operations may be reduced. Those skilled in the art may make appropriate modifications based on the above content, and are not limited to the description of FIG8 above.

[0191] In the embodiment of the present application, the random access process is a random access process in LTM;

[0192] For example, the random access procedure is initiated for LTM cell change, or the random access procedure is a random access procedure when LTM is in progress.

[0193] In some embodiments, the random access procedure is CFRA or CBRA.

[0194] In the embodiment of the present application, “2-step random access resources” may also be replaced by “resources configured for 2-step RA type random access”.

[0195] In some embodiments, configuring the 2-step random access resource includes at least one of the following:

[0196] Configure 2-step CFRA resources. For example, include cfra-TwoStep in RACH-ConfigDedicated.

[0197] Configure 2-step CBRA resources. For example, run rach-ConfigCommonTwoStepRA.

[0198] The above embodiments are merely exemplary of the present invention, but the present invention is not limited thereto. Appropriate modifications may be made based on the above embodiments. For example, the above embodiments may be used alone, or one or more of the above embodiments may be combined.

[0199] Through the embodiments of the present application, for LTM, when a network device configures 2-step random access resources for a terminal device, the LTM CSC MAC CE sent by the network device to the terminal device does not explicitly indicate CFRA resources or explicitly indicates a subset of RACH opportunities for uplink carriers from RACH ConfigDedicated. This ensures that the terminal device performs the expected behavior, i.e., the expected type of random access procedure, avoids different implementations by different manufacturers, and thus reduces deployment costs caused by testing.

[0200] Embodiments of the third aspect

[0201] An embodiment of the present application provides a random access method in LTM cell change, which is applied to a terminal device.

[0202] FIG9 is a schematic diagram of a random access method in an LTM cell change according to an embodiment of the present application. As shown in FIG9 , the method includes:

[0203] 901: The terminal device receives the LTM CSC MAC CE from the network device.

[0204] The CFRA resources indicated by the LTM CSC MAC CE are 2-step random access resources, or the CFRA resources indicated by the LTM CSC MAC CE do not include 2-step random access resources.

[0205] It is worth noting that FIG9 above is merely a schematic illustration of an embodiment of the present application, and the present application is not limited thereto. For example, the execution order of the various operations may be appropriately adjusted, and other operations may be added or some operations may be reduced. Those skilled in the art may make appropriate modifications based on the above content, and are not limited to the description of FIG9 above.

[0206] In the embodiment of the present application, the random access procedure is a random access procedure in LTM; for example, the random access procedure is initiated for LTM cell change, or the random access procedure is a random access procedure when LTM is in progress.

[0207] In some embodiments, the CFRA resource indicated by the LTM CSC MAC CE is a 2-step random access resource.

[0208] In the embodiment of the present application, "2-step random access resources" can also be replaced by "resources configured for 2-step RA type random access", that is, the CFRA resources indicated by the LTM CSC MAC CE are resources configured for 2-step RA type random access.

[0209] In some embodiments, the CFRA resource is indicated by the PRACH Mask index field in the LTM CSC MAC CE.

[0210] In some embodiments, the CFRA resource indicated by the LTM CSC MAC CE is a 2-step random access resource, including:

[0211] The PRACH Mask index field indicates a subset of RACH occasion(s) for 2-step RA from the RACH-ConfigDedicated; or,

[0212] The PRACH Mask index field indicates a subset of RACH occasion(s) from cfra-TwoStep in the RACH-ConfigDedicated; or,

[0213] The PRACH Mask index field indicates a subset of RACH occasion(s) from the rach-ConfigCommon for the UL carrier (indicated by S / U field) in the UL BWP configuration of firstActiveUplinkBWP-Id; or,

[0214] The PRACH Mask index field indicates a subset of RACH occasion(s) from rach-ConfigCommonTwoStepRA for the UL carrier (indicated by S / U field) in the UL BWP configuration of firstActiveUplinkBWP-Id.

[0215] In some embodiments, the CFRA resource indicated by the LTM CSC MAC CE is a 2-step random access resource, including: the LTM CSC MAC CE includes a field indicating the RA type, for example, the field indicating 4-step RA and / or 2-step RA. For example, when the field is set to 1, it indicates that the MAC CE provides 4-step CFRA resources / information; when the field is set to 0, it indicates that the MAC CE provides 2-step CFRA resources / information. Alternatively, when the field is set to 1, it indicates that the MAC CE provides 2-step CFRA resources / information; when the field is set to 0, it indicates that the MAC CE provides 4-step CFRA resources / information.

[0216] In some embodiments, the CFRA resources indicated by the LTM CSC MAC CE do not include 2-step random access resources. For example, the CFRA resources indicated by the LTM CSC MAC CE only include 4-step random access resources.

[0217] In some embodiments, the CFRA resource is indicated by the PRACH Mask index field in the LTM CSC MAC CE.

[0218] For example, the CFRA resources indicated by the LTM CSC MAC CE do not include 2-step random access resources, including: the PRACH Mask index field indicates a subset of RACH occasions configured for 4-step RA from the RACH-ConfigDedicated for the uplink carrier, that is, a subset of RACH occasion(s) configured for 4-step RA from the RACH-ConfigDedicated for the UL carrier (indicated by S / U field).

[0219] For example, the CFRA resources indicated by the LTM CSC MAC CE do not include 2-step random access resources, including: when the RACH-ConfigDedicated includes cfra, the PRACH Mask index field indicates the RACH opportunity configured for 4-step RA in the RACH-ConfigDedicated for the uplink carrier or a subset of the RACH opportunities indicated by the cfra.

[0220] For example, the CFRA resources indicated by the LTM CSC MAC CE do not include 2-step random access resources, including: when the RACH-ConfigDedicated does not include cfra, the PRACH Mask index field indicates a subset of RACH occasion(s) from the rach-ConfigCommon.

[0221] For example, the CFRA resources indicated by the LTM CSC MAC CE do not include 2-step random access resources, including: when the RACH-ConfigDedicated includes cfra-TwoStep, the PRACH Mask index field indicates a subset of RACH occasion(s) from the rach-ConfigCommon.

[0222] Through the embodiments of the present application, the CFRA resources indicated by the LTM CSC MAC CE received by the terminal device from the network device are 2-step random access resources, or the CFRA resources indicated by the LTM CSC MAC CE do not include 2-step random access resources. This ensures that the network and the terminal have a consistent understanding of random access resources, eliminates implementation uncertainty among different terminal manufacturers, and reduces testing costs.

[0223] Embodiments of the fourth aspect

[0224] The embodiment of the present application provides a random access method in LTM cell change, which is applied to a network device. The method corresponds to the method applied to a terminal device in the embodiment of the third aspect, and the relevant content can refer to the description of the embodiment of the third aspect.

[0225] FIG10 is another schematic diagram of a random access method in an LTM cell change according to an embodiment of the present application. As shown in FIG10 , the method includes:

[0226] 1001: The network device sends an LTM CSC MAC CE to the terminal device. The CFRA resource indicated by the LTM CSC MAC CE is a 2-step random access resource, or the CFRA resource indicated by the LTM CSC MAC CE does not include a 2-step random access resource.

[0227] It is worth noting that FIG10 above is merely a schematic illustration of an embodiment of the present application, and the present application is not limited thereto. For example, the execution order of the various operations may be appropriately adjusted, and other operations may be added or some operations may be reduced. Those skilled in the art may make appropriate modifications based on the above content, and are not limited to the description of FIG10 above.

[0228] In some embodiments, the CFRA resource indicated by the LTM CSC MAC CE is a 2-step random access resource.

[0229] In the embodiment of the present application, "2-step random access resources" can also be replaced by "resources configured for 2-step RA type random access", that is, the CFRA resources indicated by the LTM CSC MAC CE are resources configured for 2-step RA type random access.

[0230] In some embodiments, the CFRA resource is indicated by the PRACH Mask index field in the LTM CSC MAC CE.

[0231] In some embodiments, the CFRA resource indicated by the LTM CSC MAC CE is a 2-step random access resource, including:

[0232] The PRACH Mask index field indicates a subset of RACH occasion(s) for 2-step RA from the RACH-ConfigDedicated; or,

[0233] The PRACH Mask index field indicates a subset of RACH occasion(s) from cfra-TwoStep in the RACH-ConfigDedicated; or,

[0234] The PRACH Mask index field indicates a subset of RACH occasion(s) from the rach-ConfigCommon for the UL carrier (indicated by S / U field) in the UL BWP configuration of firstActiveUplinkBWP-Id; or,

[0235] The PRACH Mask index field indicates a subset of RACH occasion(s) from rach-ConfigCommonTwoStepRA for the UL carrier (indicated by S / U field) in the UL BWP configuration of firstActiveUplinkBWP-Id.

[0236] In some embodiments, the CFRA resource indicated by the LTM CSC MAC CE is a 2-step random access resource. For example, the LTM CSC MAC CE includes a field indicating the RA type, for example, the field indicates 4-step RA or 2-step RA.

[0237] In some embodiments, the CFRA resources indicated by the LTM CSC MAC CE do not include 2-step random access resources, including: the CFRA resources indicated by the LTM CSC MAC CE only include 4-step random access resources.

[0238] In some embodiments, the CFRA resource is indicated by the PRACH Mask index field in the LTM CSC MAC CE.

[0239] For example, the CFRA resources indicated by the LTM CSC MAC CE do not include 2-step random access resources, including: the PRACH Mask index field indicates a subset of RACH occasions configured for 4-step RA from the RACH-ConfigDedicated for the uplink carrier, that is, a subset of RACH occasion(s) configured for 4-step RA from the RACH-ConfigDedicated for the UL carrier (indicated by S / U field).

[0240] For example, the CFRA resources indicated by the LTM CSC MAC CE do not include 2-step random access resources, including: when the RACH-ConfigDedicated includes cfra, the PRACH Mask index field indicates the RACH opportunity configured for 4-step RA in the RACH-ConfigDedicated for the uplink carrier or a subset of the RACH opportunities indicated by the cfra.

[0241] For example, the CFRA resources indicated by the LTM CSC MAC CE do not include 2-step random access resources, including: when the RACH-ConfigDedicated does not include cfra, the PRACH Mask index field indicates a subset of RACH occasion(s) from the rach-ConfigCommon.

[0242] For example, the CFRA resources indicated by the LTM CSC MAC CE do not include 2-step random access resources, including: when the RACH-ConfigDedicated includes cfra-TwoStep, the PRACH Mask index field indicates a subset of RACH occasion(s) from the rach-ConfigCommon.

[0243] Through the embodiments of the present application, the CFRA resources indicated by the LTM CSC MAC CE sent by the network device to the terminal device are 2-step random access resources, or the CFRA resources indicated by the LTM CSC MAC CE do not include 2-step random access resources. This ensures that the network and the terminal have a consistent understanding of random access resources, eliminates implementation uncertainty among different terminal manufacturers, and reduces testing costs.

[0244] Embodiments of the fifth aspect

[0245] An embodiment of the present application provides a random access method in LTM cell change, which is applied to a terminal device.

[0246] FIG11 is a schematic diagram of a random access method in an LTM cell change according to an embodiment of the present application. As shown in FIG11 , the method includes:

[0247] 1101: The terminal device receives RACH-ConfigDedicated from the network device;

[0248] 1102: When cfra and cfra-TwoStep do not exist in the RACH-ConfigDedicated, and the random access procedure is not initiated for an LTM cell change, the terminal device performs CBRA; and / or

[0249] 1103: When cfra or cfra-TwoStep exists in the RACH-ConfigDedicated, the terminal device performs CFRA.

[0250] It is worth noting that FIG11 above is merely a schematic illustration of an embodiment of the present application, and the present application is not limited thereto. For example, the execution order of the various operations may be appropriately adjusted, and other operations may be added or some operations may be reduced. Those skilled in the art may make appropriate modifications based on the above content, and are not limited to the description of FIG11 above.

[0251] In some embodiments, as shown in FIG11 , the method further includes:

[0252] 1104: The terminal device receives the LTM CSC MAC CE from the network device;

[0253] 1105: When the LTM CSC MAC CE explicitly indicates CFRA resources, the terminal device performs CFRA.

[0254] Steps 1104 and 1105 are optional steps and are indicated by dashed boxes in FIG11 .

[0255] In some embodiments, for operation 1105, the LTM CSC MAC CE explicitly indicates CFRA resources, including at least one of the following:

[0256] The C field in the LTM CSC MAC CE indicates the existence of the CFRA resource field (contention-free Random Access Resources field);

[0257] The value of the C field in the LTM CSC MAC CE is set to 1;

[0258] The LTM CSC MAC CE includes one of a random access preamble index field, an S / U field (SS / PBCH index field), an SS / PBCH index field, a PRACH Mask index field, and a repetition number field.

[0259] In some embodiments, the CFRA random access procedure is initiated for an LTM cell change.

[0260] According to the embodiments of the present application, when the terminal device receives a RACH-ConfigDedicated message from a network device and does not contain cfra or cfra-TwoStep, and the random access procedure is not initiated for an LTM cell change, the terminal device performs CBRA; and / or when the RACH-ConfigDedicated message contains cfra or cfra-TwoStep, the terminal device performs CFRA. In this way, the correct type of random access procedure can be performed in a timely manner, unnecessary random access procedures can be avoided, and additional access delays can be avoided.

[0261] Embodiments of the sixth aspect

[0262] The embodiment of the present application provides a random access device for LTM cell change. The device corresponds to the method described in the embodiment of the first aspect. The device can be, for example, a terminal device, or one or more components or assemblies configured in the terminal device. The same contents as those in the embodiment of the first aspect are not repeated here.

[0263] FIG12 is a schematic diagram of a random access apparatus in an LTM cell change according to an embodiment of the present application. As shown in FIG12 , a random access apparatus 1200 in an LTM cell change includes:

[0264] A first determining unit 1201 determines, when a 2-step random access resource is configured, that the random access process of the terminal device uses a 2-step random access type; or

[0265] The second determining unit 1202 determines that the random access process of the terminal device uses the 4-step random access type when the 2-step random access resource is configured.

[0266] In some embodiments, when the random access procedure of the terminal device uses a 2-step random access type, the configured 2-step random access resource includes at least one of the following:

[0267] 2-step CFRA resources are configured;

[0268] 2-step CBRA resources are configured.

[0269] In some embodiments, the configuration of the 2-step CFRA resource includes: RACH-ConfigDedicated includes cfra-TwoStep; and / or,

[0270] The configuration of the 2-step CBRA resource includes: configuring rach-ConfigCommonTwoStepRA.

[0271] In some embodiments, the 2-step random access type is used, including:

[0272] During random access initialization, the MAC entity of the terminal device sets RA_TYPE to 2-stepRA.

[0273] In some embodiments, the apparatus 1200 further includes:

[0274] The first receiving unit 1203 receives an LTM CSC MAC CE from a network device.

[0275] The LTM CSC MAC CE does not explicitly indicate CFRA resources or explicitly indicates a subset of RACH opportunities for uplink carriers from RACH ConfigDedicated.

[0276] In some embodiments, for RACH-based LTM cell change, 2-step RA type CFRA is supported.

[0277] In some embodiments, the apparatus 1200 further includes:

[0278] The third determining unit 1204 is configured to determine, when the terminal device is configured with a 4-step random access resource, that the random access process of the terminal device uses a 4-step random access type.

[0279] In some embodiments, the configured 4-step random access resource includes at least one of the following:

[0280] 4-step CFRA resources are configured;

[0281] 4-step CBRA resources are configured.

[0282] In some embodiments, the 4-step CFRA resource is configured, including: RACH-ConfigDedicated includes cfra; and / or,

[0283] This configures the 4-step CBRA resources, including: configuring rach-ConfigCommon.

[0284] In some embodiments, the 4-step random access type is used, including:

[0285] During random access initialization, MAC sets RA_TYPE to 4-stepRA.

[0286] In some embodiments, the apparatus further comprises:

[0287] The fourth determining unit 1205 determines the random access type used in the random access process of the terminal device according to the reference signal received power (RSRP) when no 2-step random access resources and 4-step random access resources are configured for the terminal device.

[0288] In some embodiments, the 2-step random access resource is a 2-step CFRA resource.

[0289] The 4-step random access resource is a 4-step CFRA resource.

[0290] In some embodiments, in the case where the random access procedure of the terminal device uses a 4-step random access type, the CFRA resources of the 2-step RA type in the 2-step random access resources are not used for LTM cell change.

[0291] In some embodiments, the apparatus 1200 further includes:

[0292] The fifth determining unit 1206 determines that the random access process of the terminal device uses the 2-step random access type when a CFRA resource of the 2-step RA type is configured for the cell handover,

[0293] This cell handover does not include LTM cell change.

[0294] In some embodiments, in the case where the random access procedure of the terminal device uses a 4-step random access type, a CFRA resource of a 2-step RA type in the 2-step random access resource is not configured for the LTM.

[0295] In some embodiments, the random access procedure is CFRA or CBRA.

[0296] In some embodiments, the random access procedure is initiated for LTM cell change, or the random access procedure is a random access procedure when LTM is in progress.

[0297] It is worth noting that the above only describes the components or modules related to the present application, but the present application is not limited thereto. The random access apparatus 1200 in LTM cell change may also include other components or modules. For the specific contents of these components or modules, reference may be made to the relevant art.

[0298] In addition, for the sake of simplicity, FIG12 only illustrates the connection relationship or signal direction between various components or modules. However, it should be clear to those skilled in the art that various related technologies such as bus connection can be used. The above-mentioned components or modules can be implemented by hardware facilities such as processors, memories, transmitters, and receivers; the implementation of this application is not limited to this.

[0299] Through the embodiments of the present application, for LTM, when a terminal device is configured with 2-step random access resources, the terminal device's random access process uses the 2-step random access type, or the terminal device's random access process uses the 4-step random access type. This ensures that the terminal device performs the expected behavior, i.e., performs the expected type of random access process, avoids different implementations by different manufacturers, and thus reduces deployment costs caused by testing.

[0300] Embodiments of the seventh aspect

[0301] The embodiment of the present application provides a random access device for LTM cell change. The device corresponds to the method described in the embodiment of the second aspect. The device can be, for example, a network device, or one or more components or assemblies configured on the network device. The contents that are the same as those in the embodiment of the second aspect are not repeated here.

[0302] FIG13 is a schematic diagram of a random access apparatus in an LTM cell change according to an embodiment of the present application. As shown in FIG13 , a random access apparatus 1300 in an LTM cell change includes:

[0303] The configuration unit 1301 configures 2-step random access resources to the terminal device, and the 2-step random access resources cannot be used for LTM; or, the configuration unit 1301 does not configure 2-step random access resources used in LTM cell change to the terminal device.

[0304] In some embodiments, the configuration unit 1301 configures a 2-step random access resource to the terminal device, and the 2-step random access resource cannot be used for LTM. For example, when the terminal device is configured with the 2-step random access resource, its random access process uses a 4-step random access type.

[0305] In some embodiments, the configuration unit 1301 does not configure 2-step random access resources for LTM cell change to the terminal device. For example, it only configures 4-step random access CFRA resources for LTM cell change to the terminal device.

[0306] In the embodiment of the present application, the random access process is a random access process in LTM;

[0307] For example, the random access procedure is initiated for LTM cell change, or the random access procedure is a random access procedure when LTM is in progress.

[0308] In some embodiments, the random access procedure is CFRA or CBRA.

[0309] In the embodiment of the present application, “2-step random access resources” may also be replaced by “resources configured for 2-step RA type random access”.

[0310] In some embodiments, configuring the 2-step random access resource includes at least one of the following:

[0311] Configure 2-step CFRA resources. For example, include cfra-TwoStep in RACH-ConfigDedicated.

[0312] Configure 2-step CBRA resources. For example, run rach-ConfigCommonTwoStepRA.

[0313] The above embodiments are merely exemplary of the present invention, but the present invention is not limited thereto. Appropriate modifications may be made based on the above embodiments. For example, the above embodiments may be used alone, or one or more of the above embodiments may be combined.

[0314] It is worth noting that the above only describes the components or modules related to the present application, but the present application is not limited thereto. The random access apparatus 1300 in LTM cell change may also include other components or modules. For the specific contents of these components or modules, reference may be made to the relevant art.

[0315] In addition, for the sake of simplicity, FIG13 only illustrates the connection relationship or signal direction between various components or modules. However, it should be clear to those skilled in the art that various related technologies such as bus connection can be used. The above-mentioned components or modules can be implemented by hardware facilities such as processors, memories, transmitters, and receivers; the implementation of this application is not limited to this.

[0316] Through the embodiments of the present application, for LTM, when a network device configures 2-step random access resources for a terminal device, the LTM CSC MAC CE sent by the network device to the terminal device does not explicitly indicate CFRA resources or explicitly indicates a subset of RACH opportunities for uplink carriers from RACH ConfigDedicated. This ensures that the terminal device performs the expected behavior, i.e., the expected type of random access procedure, avoids different implementations by different manufacturers, and thus reduces deployment costs caused by testing.

[0317] Embodiments of the eighth aspect

[0318] An embodiment of the present application provides a terminal device, which can execute the random access method in the LTM cell change described in the embodiment of the first aspect, or the random access method in the LTM cell change described in the third aspect and / or the random access method in the LTM cell change described in the fifth aspect.

[0319] Figure 14 is a schematic block diagram of the system architecture of a terminal device according to an embodiment of the present invention. As shown in Figure 14 , terminal device 1400 may include a processor 1410 and a memory 1420; memory 1420 is coupled to processor 1410. It should be noted that this diagram is exemplary; other types of structures may be used to supplement or replace this structure to implement telecommunication or other functions.

[0320] In one embodiment, the terminal device executes the random access method in the LTM cell change described in the embodiment of the first aspect, and the processor 1410 is configured to: when the terminal device is configured with 2-step random access resources, the random access process of the terminal device uses a 2-step random access type; or, when the terminal device is configured with 2-step random access resources, the random access process of the terminal device uses a 4-step random access type.

[0321] In another embodiment, the terminal device executes the random access method in the LTM cell change described in the embodiment of the third aspect, and the processor 1410 is configured as: the terminal device receives an LTM CSC MAC CE from the network device, and the CFRA resources indicated by the LTM CSC MAC CE are 2-step random access resources, or the CFRA resources indicated by the LTM CSC MAC CE do not include 2-step random access resources.

[0322] In another embodiment, the terminal device executes the random access method in the LTM cell change described in the fifth aspect, and the processor 1410 is configured to: the terminal device receives RACH-ConfigDedicated from the network device; when cfra and cfra-TwoStep do not exist in the RACH-ConfigDedicated and the random access process is not initiated for the LTM cell change, the terminal device performs CBRA; and / or when cfra or cfra-TwoStep exists in the RACH-ConfigDedicated, the terminal device performs CFRA.

[0323] As shown in FIG14 , terminal device 1400 may further include: a communication module 1430, an input unit 1440, a display 1450, and a power supply 1460. It is worth noting that terminal device 1400 does not necessarily include all the components shown in FIG14 ; in addition, terminal device 1400 may also include components not shown in FIG14 , and reference may be made to related art for details.

[0324] As shown in FIG. 14 , the processor 1410 is sometimes also referred to as a controller or an operation control, and may include a microprocessor or other processor device and / or logic device. The processor 1410 receives inputs and controls the operations of various components of the terminal device 1400 .

[0325] Memory 1420 may be, for example, one or more of a cache, flash memory, a hard drive, removable media, volatile memory, non-volatile memory, or other suitable devices. It may store various data and may also store programs for executing related information. Processor 1410 may execute the programs stored in memory 1420 to implement information storage or processing. The functions of other components are similar to those of existing devices and are not further described here. Each component of terminal device 1400 may be implemented using dedicated hardware, firmware, software, or a combination thereof without departing from the scope of the present invention.

[0326] Through the embodiments of the present application, for LTM, when a terminal device is configured with 2-step random access resources, the terminal device's random access process uses the 2-step random access type, or the terminal device's random access process uses the 4-step random access type. This ensures that the terminal device performs the expected behavior, i.e., performs the expected type of random access process, avoids different implementations by different manufacturers, and thus reduces deployment costs caused by testing.

[0327] In addition, the CFRA resources indicated by the LTM CSC MAC CE received by the terminal device from the network device are 2-step random access resources, or the CFRA resources indicated by the LTM CSC MAC CE do not include 2-step random access resources. This ensures that the network and the terminal have a consistent understanding of random access resources, eliminates implementation uncertainty among different terminal manufacturers, and reduces testing costs.

[0328] In addition, when the terminal device does not contain cfra or cfra-TwoStep in the RACH-ConfigDedicated received from the network device, and the random access procedure is not initiated for an LTM cell change, the terminal device performs CBRA; and / or when cfra or cfra-TwoStep is present in the RACH-ConfigDedicated, the terminal device performs CFRA. In this way, the correct type of random access procedure can be performed in a timely manner, avoiding unnecessary random access procedures and introducing additional access delays.

[0329] Embodiments of the ninth aspect

[0330] An embodiment of the present application provides a network device, which can execute the random access method in the LTM cell change described in the embodiment of the second aspect and / or the random access method in the LTM cell change described in the fourth aspect.

[0331] Figure 15 is a schematic block diagram of the system configuration of a network device according to an embodiment of the present application. As shown in Figure 15 , network device 1500 may include a processor 1510 and a memory 1520; memory 1520 is coupled to processor 1510. Memory 1520 can store various data and also stores an information processing program 1530. This program 1530 is executed under the control of processor 1510 to receive various information sent by terminal devices and to send various information to terminal devices.

[0332] In one embodiment, the network device executes the random access method in the LTM cell change described in the embodiment of the second aspect, and the processor 1510 can be configured as: the network device configures 2-step random access resources to the terminal device, and the 2-step random access resources cannot be used for LTM; or, the network device does not configure 2-step random access resources for the LTM cell change to the terminal device.

[0333] In another embodiment, the network device executes the random access method in the LTM cell change described in the fourth aspect, and the processor 1510 can be configured as: the network device sends an LTM CSC MAC CE to the terminal device, and the CFRA resources indicated by the LTM CSC MAC CE are 2-step random access resources, or the CFRA resources indicated by the LTM CSC MAC CE do not include 2-step random access resources.

[0334] In addition, as shown in FIG15 , network device 1500 may further include: a transceiver 1540 and an antenna 1550, etc.; wherein, the functions of the above components are similar to those in the prior art and are not described in detail here. It is worth noting that network device 1500 does not necessarily include all the components shown in FIG15 ; in addition, network device 1500 may also include components not shown in FIG15 , and reference may be made to the prior art for details.

[0335] As can be seen from the above embodiment, for LTM, when the network device configures 2-step random access resources for the terminal device, the LTM CSC MAC CE sent by the network device to the terminal device does not explicitly indicate CFRA resources or explicitly indicates a subset of RACH opportunities for uplink carriers from the RACH ConfigDedicated. This ensures that the terminal device performs the expected behavior, that is, the expected type of random access procedure, avoids different implementation methods among different manufacturers, and thus reduces deployment costs caused by testing.

[0336] In addition, the CFRA resource indicated by the LTM CSC MAC CE sent by the network device to the terminal device is a 2-step random access resource, or the CFRA resource indicated by the LTM CSC MAC CE does not include a 2-step random access resource. This ensures that the network and the terminal have a consistent understanding of random access resources, eliminates implementation uncertainty among different terminal manufacturers, and reduces testing costs.

[0337] Embodiments of the tenth aspect

[0338] The embodiment of the present application provides a communication system, including the terminal device according to the embodiment of the eighth aspect and / or the network device according to the embodiment of the ninth aspect. For specific content, please refer to the description of the embodiment of the eighth aspect and the embodiment of the ninth aspect.

[0339] For example, the structure of the communication system can refer to Figure 5. As shown in Figure 5, the communication system 100 includes a network device 101 and a terminal device 102. The terminal device 102 can be the same as the terminal device recorded in the embodiment of the eighth aspect, and / or, the network device 101 can be the same as the network device recorded in the embodiment of the ninth aspect. The repeated content will not be repeated.

[0340] The above devices and methods of the present application can be implemented by hardware or by a combination of hardware and software. The present application relates to such a computer-readable program that, when executed by a logic component, enables the logic component to implement the devices or components described above, or enables the logic component to implement the various methods or steps described above. The present application also relates to a storage medium for storing the above program, such as a hard disk, a magnetic disk, an optical disk, a DVD, a flash memory, etc.

[0341] The method / device described in conjunction with the embodiments of the present application can be directly embodied as hardware, a software module executed by a processor, or a combination of the two. For example, one or more of the functional block diagrams shown in Figure 12 and / or one or more combinations of functional block diagrams can correspond to various software modules of a computer program flow or to various hardware modules. These software modules can correspond to the various steps shown in Figure 7, respectively. These hardware modules can be implemented by solidifying these software modules, for example, using a field programmable gate array (FPGA).

[0342] The software module may be located in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. A storage medium may be coupled to a processor so that the processor can read information from the storage medium and write information to the storage medium; or the storage medium may be an integral part of the processor. The processor and the storage medium may be located in an ASIC. The software module may be stored in the memory of the mobile terminal or in a memory card that can be inserted into the mobile terminal. For example, if the device (such as a mobile terminal) uses a large-capacity MEGA-SIM card or a large-capacity flash memory device, the software module may be stored in the MEGA-SIM card or the large-capacity flash memory device.

[0343] One or more of the functional blocks and / or one or more combinations of functional blocks described in FIG12 may be implemented as a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, or any suitable combination thereof for performing the functions described in this application. One or more of the functional blocks and / or one or more combinations of functional blocks described in FIG12 may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in communication with a DSP, or any other such configuration.

[0344] The present application has been described above in conjunction with specific embodiments. However, those skilled in the art should understand that these descriptions are merely illustrative and are not intended to limit the scope of protection of the present application. Those skilled in the art may make various modifications and variations to the present application based on the spirit and principles of the present application, and such modifications and variations are also within the scope of the present application.

[0345] According to various implementations disclosed in the examples of this application, the following notes are also disclosed:

[0346] Notes

[0347] 1. A random access device in LTM cell change, the device being provided in a terminal device, the device comprising:

[0348] A second receiving unit receives an LTM CSC MAC CE from a network device,

[0349] The CFRA resources indicated by the LTM CSC MAC CE are 2-step random access resources, or the CFRA resources indicated by the LTM CSC MAC CE do not include 2-step random access resources.

[0350] 2. The device according to Supplement 1, wherein:

[0351] The CFRA resources indicated by the LTM CSC MAC CE do not include 2-step random access resources, but include:

[0352] The CFRA resources indicated by the LTM CSC MAC CE include only 4-step random access resources.

[0353] 3. The device according to Supplement 1, wherein:

[0354] The CFRA resource is indicated by the PRACH Mask index field in the LTM CSC MAC CE.

[0355] 4. The apparatus according to Note 3, wherein the CFRA resource indicated by the LTM CSC MAC CE is a 2-step random access resource, including at least one of the following:

[0356] The PRACH Mask index field indicates a subset of RACH opportunities for 2-step RA in RACH-ConfigDedicated;

[0357] The PRACH Mask index field indicates a subset of RACH opportunities from cfra-TwoStep in RACH-ConfigDedicated;

[0358] The PRACH Mask index field indicates a subset of the RACH opportunities of rach-ConfigCommon for the uplink carrier in the uplink BWP configuration of firstActiveUplinkBWP-Id;

[0359] The PRACH Mask index field indicates the subset of RACH opportunities of rach-ConfigCommonTwoStepRA for the uplink carrier in the uplink BWP configuration of firstActiveUplinkBWP-Id;

[0360] The LTM CSC MAC CE includes a field indicating the RA type.

[0361] 5. The apparatus according to Note 3, wherein the CFRA resource indicated by the LTM CSC MAC CE does not include a 2-step random access resource, and includes at least one of the following:

[0362] The PRACH Mask Index field indicates a subset of RACH opportunities configured for 4-step RA from the RACH-ConfigDedicated field for the uplink carrier;

[0363] When the RACH-ConfigDedicated includes cfra, the PRACH Mask Index field indicates the RACH opportunity configured for 4-step RA in the RACH-ConfigDedicated for the uplink carrier or a subset of the RACH opportunities indicated by the cfra;

[0364] When the RACH-ConfigDedicated does not include cfra or includes cfra-TwoStep, the PRACH Mask index field indicates a subset of RACH opportunities from rach-ConfigCommon.

[0365] 6. A random access device in LTM cell change, the device being provided in a network device, the device comprising:

[0366] A sending unit, which sends an LTM CSC MAC CE to a terminal device,

[0367] The CFRA resources indicated by the LTM CSC MAC CE are 2-step random access resources, or the CFRA resources indicated by the LTM CSC MAC CE do not include 2-step random access resources.

[0368] 7. A random access device in LTM cell change, the device being provided in a terminal device, the device comprising:

[0369] a third receiving unit, configured to receive a RACH-ConfigDedicated from the network device;

[0370] When cfra and cfra-TwoStep do not exist in the RACH-ConfigDedicated and the random access procedure is not initiated for an LTM cell change, the terminal device performs CBRA; and / or

[0371] When cfra or cfra-TwoStep exists in the RACH-ConfigDedicated, the terminal device performs CFRA.

[0372] 8. The device according to Supplementary Note 7, wherein:

[0373] The third receiving unit further receives an LTM CSC MAC CE from the network device;

[0374] When the LTM CSC MAC CE explicitly indicates CFRA resources, the terminal device performs CFRA.

[0375] 9. The apparatus according to note 8, wherein the LTM CSC MAC CE explicitly indicates CFRA resources, including at least one of the following:

[0376] The C field in the LTM CSC MAC CE indicates the presence of the CFRA resource field;

[0377] The value of the C field in the LTM CSC MAC CE is set to 1;

[0378] The LTM CSC MAC CE includes one of a random access preamble index field, an S / U field, an SS / PBCH index field, a PRACH Mask index field, and a repetition number field.

[0379] 10. The device according to Supplementary Note 8, wherein:

[0380] The random access procedure of CFRA is initiated for LTM cell change.

Claims

1. A device for determining a random access type in an LTM cell change, the device being configured in a terminal device and comprising: A first determining unit, which determines that the random access process of the terminal device uses a 2-step random access type when a 2-step random access resource is configured; or The second determining unit determines that the random access process of the terminal device uses a 4-step random access type when a 2-step random access resource is configured.

2. The device according to claim 1, wherein In the case where the random access process of the terminal device uses a 2-step random access type, the configured 2-step random access resource includes at least one of the following: 2-step CFRA resources are configured; 2-step CBRA resources are configured.

3. The device according to claim 2, wherein The configuration of 2-step CFRA resources includes: RACH-ConfigDedicated includes cfra-TwoStep; and / or, The configuring of the 2-step CBRA resource includes configuring rach-ConfigCommonTwoStepRA.

4. The device according to claim 1, wherein The 2-step random access type includes: During random access initialization, the MAC entity of the terminal device sets RA_TYPE to 2-stepRA.

5. The device according to claim 1, wherein The device further comprises: A first receiving unit receives an LTM CSC MAC CE from a network device, The LTM CSC MAC CE does not explicitly indicate CFRA resources or explicitly indicates a subset of RACH opportunities for uplink carriers from RACH ConfigDedicated.

6. The device according to claim 1, wherein For RACH-based LTM cell change, CFRA of 2-step RA type is supported.

7. The device according to claim 1, wherein The device further comprises: The third determining unit determines, when the terminal device is configured with a 4-step random access resource, that the random access process of the terminal device uses a 4-step random access type.

8. The device according to claim 7, wherein The 4-step random access resource is configured to include at least one of the following: 4-step CFRA resources are configured; 4-step CBRA resources are configured.

9. The device according to claim 8, wherein The 4-step CFRA resource is configured, including: RACH-ConfigDedicated includes cfra; and / or, The 4-step CBRA resources are configured, including: configuring rach-ConfigCommon.

10. The device according to claim 1 or 7, wherein: The 4-step random access type is used, including: During random access initialization, MAC sets RA_TYPE to 4-stepRA.

11. The device according to claim 1 or 7, wherein: The device further comprises: A fourth determination unit determines the random access type used in the random access process of the terminal device according to the reference signal received power (RSRP) when no 2-step random access resources and 4-step random access resources are configured for the terminal device.

12. The device according to claim 11, wherein The 2-step random access resource is a 2-step CFRA resource. The 4-step random access resource is a 4-step CFRA resource.

13. The device according to claim 1, wherein In the case where the random access procedure of the terminal device uses a 4-step random access type, the CFRA resources of the 2-step RA type in the 2-step random access resources are not used for LTM cell change.

14. The device according to claim 13, wherein The device further comprises: a fifth determining unit, which, when a CFRA resource of a 2-step RA type is configured for cell handover, determines that the random access process of the terminal device uses a 2-step random access type, The cell handover does not include LTM cell change.

15. The device according to claim 1, wherein In the case where the random access process of the terminal device uses the 4-step random access type, the CFRA resources of the 2-step RA type in the 2-step random access resources are not configured for the LTM.

16. The device according to claim 1, wherein The random access procedure is CFRA or CBRA.

17. The device according to claim 16, wherein The random access procedure is initiated for LTM cell change, or, The random access procedure is a random access procedure when LTM is in progress.

18. A random access device in LTM cell change, the device being provided in a network device, the device comprising: a configuration unit configured to configure a 2-step random access resource to the terminal device, wherein the 2-step random access resource cannot be used for LTM; Alternatively, it does not configure the terminal device with 2-step random access resources for LTM cell change.

19. The device according to claim 18, wherein The 2-step random access resource includes at least one of the following: 2-step CFRA resources; 2-step CBRA resources.

20. A communication system, comprising a terminal device and / or a network device, The terminal device includes the apparatus according to claim 1, The network device comprises the apparatus according to claim 18.

Images