Communication method and device

Abstract

This application discloses a communication method and apparatus in the field of communication technology. The method includes the steps of: receiving a random access request from a first terminal in a first cell; determining whether the random access request corresponds to a first random access or a second random access; transmitting a TA of the first cell to a first network device when the random access request corresponds to a first random access, or transmitting a TA of the first cell to a first terminal when the random access request corresponds to a second random access, wherein the first random access is a pre-switch random access and the second random access is a post-switch random access. According to the method described above, both pre-switch random access (i.e., first random access) and post-switch random access (i.e., second random access) are supported, and one type of random access can be flexibly performed based on the actual requirements.

Description

Technical Field

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[0001] Cross - reference to related applications This application claims priority to Chinese Patent Application No. 202311015571.8, titled "COMMUNICATION METHOD AND APPARATUS", filed with the China National Intellectual Property Administration on August 10, 2023, which is incorporated herein by reference in its entirety.

[0002] This application relates to the field of communication technologies, and particularly to communication methods and apparatuses.

Background Art

[0003] Cell switching is a very important feature in a communication system. Since it is mainly triggered by the movement of a terminal when the terminal is in the radio resource control (RRC) connected state, before the signal quality of the serving cell becomes unable to support communication, the terminal switches to an adjacent cell with good signal quality, thereby providing a continuous and uninterrupted communication service.

[0004] A scenario where a terminal switches from Cell 1 to Cell 2 is used as an example. The terminal needs to obtain the timing advance (TA) of Cell 2. For example, the terminal may obtain the TA of Cell 2 through random access and then transmit uplink information within Cell 2 based on the TA of Cell 2.

[0005] However, further research is required for the related implementation of obtaining TA through random access.

Summary of the Invention

Means for Solving the Problems

[0006] This application provides a communication method and apparatus for supporting both pre-switch and post-switch random access, thereby enabling flexible execution of one type of random access based on actual requirements.

[0007] According to a first aspect, one embodiment of the present application provides a communication method. The method may be applied to a network device (e.g., a second DU, the second DU being a candidate DU or a target DU) or a module within a network device (e.g., a chip or circuit). For example, the method is applied to a second DU. In the method, the second DU receives a random access request from a first terminal in a first cell, determines whether the random access request corresponds to a first random access or a second random access, and transmits a timing advance TA of the first cell to the first network device if the random access request corresponds to a first random access, or transmits a TA to the first terminal if the random access request corresponds to a second random access. The first random access is a pre-switch random access, and the second random access is a post-switch random access.

[0008] According to the method described above, after receiving a random access request from the first terminal in the first cell, the second DU may determine a specific random access type corresponding to the random access request and perform the corresponding action, thereby supporting both pre-switch random access (i.e., first random access) and post-switch random access (i.e., second random access), and allowing for flexible execution of one type of random access based on actual requirements.

[0009] In one possible design, the step of determining whether a random access request corresponds to a first random access or a second random access includes the step of determining whether the random access request corresponds to a first random access if the random access resource corresponding to the random access request is a first random access resource, or determining whether the random access request corresponds to a second random access if the random access resource corresponding to the random access request is a second random access resource.

[0010] Thus, since the first random access and the second random access may correspond to different random access resources, after receiving a random access request, the second DU can determine whether the random access request corresponds to the first or second random access based on the random access resource corresponding to the random access request, thereby facilitating implementation.

[0011] In one possible design, the method further includes the step of sending a first message to a first network device, the first message indicating that a first random access resource corresponds to a first random access and a second random access resource corresponds to a second random access.

[0012] In one possible design, the method further includes the step of receiving a first request message from a first network device, the first request message being for the allocation of random access resources corresponding to a first random access and random access resources corresponding to a second random access.

[0013] Thus, the second DU may allocate random access resources corresponding to the first random access and random access resources corresponding to the second random access based on the request of the first network device (e.g., CU), thereby facilitating flexible management and control of the CU.

[0014] In one possible design, the first random access is a contention-free random access, the first random access resource is used by multiple terminals to perform the first random access, and all of the source network devices of the multiple terminals are the second network device.

[0015] Thus, the first random access resource corresponding to the first random access may be shared by multiple terminals of the second network device (e.g., the first DU), allowing the first DU to flexibly allocate the first random access resource for use by the corresponding terminals. As a result, the utilization rate of the random access resource improves, a large number of terminals can initiate the first random access, and switch latency is reduced.

[0016] In one possible design, the second random access is a contention-free random access, and the second random access resource is used by multiple terminals to perform the second random access, with all source network devices of the multiple terminals being the second network device. In this way, the first DU can flexibly allocate the first random access resource for use by corresponding terminals to improve the utilization rate of the random access resource. Alternatively, the second random access resource is dedicated to the first terminal. This improves the success rate of the second random access.

[0017] In one possible design, the method further includes the steps of receiving first instruction information from a second network device, and determining, based on the first instruction information, that a random access request corresponds to either a first random access or a second random access.

[0018] Thus, the second DU may determine a specific random access type corresponding to a random access request based on the first instruction information of the second network device (e.g., the first DU), thereby facilitating flexible management and control of the first DU.

[0019] In one possible design, a random access request corresponds to a third random access resource, and the step of determining, based on first directive information, whether the random access request corresponds to a first or second random access includes the step of determining that the random access request corresponds to a first random access if the first directive information indicates that the third random access resource corresponds to a first random access, or determining that the random access request corresponds to a second random access if the first directive information indicates that the third random access resource corresponds to a second random access.

[0020] In one possible design, the method further includes the step of sending a second message to a first network device, the second message indicating that a third random access resource corresponds to the first random access and the second random access.

[0021] In one possible design, the method further includes the step of receiving a second request message from a first network device, the second request message being for requesting the allocation of random access resources corresponding to the first random access and the second random access.

[0022] In one possible design, both the first and second random accesses are uncontested random accesses, and a third random access resource is used by multiple terminals to perform the first and second random accesses, with all source network devices for the multiple terminals being the second network device.

[0023] In one possible design, the step of transmitting a TA to a first terminal includes the steps of: receiving second instruction information from a second network device, wherein the second instruction information indicates beam information of a first cell; and transmitting a random access response to the first terminal based on the beam information, wherein the random access response includes a TA.

[0024] Thus, the second DU may send a random access response to the first terminal based on the beam information of the first cell, and as a result the first terminal receives the random access response, thereby improving the success rate of random access.

[0025] According to a second aspect, an embodiment of the present application provides a communication method. This method may be applied to a network device (e.g., a source DU) or a module within a network device (e.g., a chip or a circuit). For example, this method is applied to a network device. In this method, the network device receives a third message from a first network device, where the third message indicates that a first random access resource corresponds to a first random access and a second random access resource corresponds to a second random access. When it is determined that a first terminal needs to initiate a first random access, the network device transmits third indication information to the first terminal. The third indication information instructs the first terminal to transmit a first random access request in a first cell on the first random access resource, or when it is determined that the first terminal needs to initiate a second random access, the network device transmits fourth indication information to the first terminal. The fourth indication information instructs the first terminal to transmit a second random access request in a first cell on the second random access resource. The first random access is a random access before switching, and the second random access is a random access after switching.

[0026] In a possible design, when it is determined that the first terminal needs to initiate a first random access, the method further includes receiving a TA of a first cell from a third network device and transmitting a switch command to the first terminal. The switch command indicates that the first cell is a target cell and the switch command includes the TA.

[0027] In a possible design, when it is determined that the first terminal needs to initiate a second random access, the method further includes transmitting second indication information to a third network device. The second indication information indicates beam information of the first cell, and the beam information is used by the third network device to transmit the TA of the first cell to the first terminal.

[0028] In one possible design, when it is determined that the first terminal needs to initiate a second random access, the method further includes a step of transmitting fifth indication information to the first terminal, where the fifth indication information indicates beam information of the first cell, and the beam information is used by the first terminal to receive the TA of the first cell.

[0029] In one possible design, the first random access is a non-competitive random access, and the first random access resource is used by a plurality of terminals to perform the first random access, and the source network devices of the plurality of terminals are all the second network device.

[0030] In one possible design, the second random access is a non-competitive random access, and the second random access resource is used by a plurality of terminals to perform the second random access, and the source network devices of the plurality of terminals are all the second network device, or the second random access resource is dedicated to the first terminal.

[0031] According to a third aspect, one embodiment of the present application provides a communication method. The method may be applied to a network device (e.g., a source DU) or a module within a network device (e.g., a chip or circuit). For example, the method is applied to a network device. In the method, the network device receives a fourth message from a second network device, the fourth message indicating that a third random access resource corresponds to a first random access and a second random access, and if it is determined that a first terminal needs to initiate a first random access, the network device sends a third instruction information to the first terminal, which instructs the first terminal to send a first random access request in a first cell on the third random access resource, or if it is determined that a second random access needs to be initiated, the network device sends a fourth instruction information to the first terminal, which instructs the first terminal to send a second random access request in a first cell on the third random access resource. The first random access is the random access before the switch, and the second random access is the random access after the switch.

[0032] In one possible design, if it is determined that a first terminal needs to initiate a first random access, the method further includes the steps of: receiving a TA of a first cell from a third network device; and sending a switch command to the first terminal, the switch command indicating that the first cell is a target cell, and the switch command includes a TA.

[0033] In one possible design, the method further includes the step of transmitting first instruction information to a third network device, wherein if the first terminal determines that it needs to initiate a first random access, the first instruction information indicates that the third random access resource corresponds to the first random access, or if the first terminal determines that it needs to initiate a second random access, the first instruction information indicates that the third random access resource corresponds to the second random access.

[0034] In one possible design, if a first terminal determines that it needs to initiate a second random access, the method further includes the step of transmitting a second instruction information to a third network device, the second instruction information indicating beam information of a first cell, the beam information being used by the third network device to transmit a TA of the first cell to the first terminal.

[0035] In one possible design, if it is determined that a first terminal needs to initiate a second random access, the method further includes the step of transmitting a fifth instruction information to the first terminal, the fifth instruction information indicating beam information of a first cell, the beam information being used by the first terminal to receive the TA of the first cell.

[0036] In one possible design, both the first and second random accesses are uncontested random accesses, and a third random access resource is used by multiple terminals to perform the first and second random accesses, with all source network devices for the multiple terminals being the second network device.

[0037] It will be understood that the methods claimed in the second or third aspect correspond to the first aspect. For the beneficial effects of the relevant technical features in the second or third aspect, please refer to the description of the first aspect. Further details will not be explained again.

[0038] According to a fourth aspect, the present application provides a communication device having functions to implement the first to third aspects. For example, the communication device includes corresponding modules, units, or means for performing the operations of the first to third aspects. The functions, units, or means may be implemented by software, by hardware, or by hardware running the corresponding software.

[0039] In one possible design, the communication device includes a processing unit and a communication unit. The communication unit may be configured to receive and transmit signals in order to facilitate communication between the communication device and another device. For example, the communication unit may be configured to transmit system information to a terminal. The processing unit may be configured to perform some internal operations of the communication device. The functions performed by the processing unit and the communication unit may correspond to the operations of the first to third embodiments.

[0040] In one possible design, the communication device includes a processor, which may be configured to be coupled to memory. The memory may store computer programs or instructions necessary to perform the functions of the first to third embodiments. The processor may execute the computer programs or instructions stored in memory. When the computer programs or instructions are executed, the communication device is made to perform a method according to any one of the possible designs or implementations of the first to third embodiments.

[0041] In one possible design, the communication device includes a processor and memory. The memory may store computer programs or instructions necessary to perform the functions of the first to third embodiments. The processor may execute the computer programs or instructions stored in the memory. When the computer programs or instructions are executed, the communication device is made to perform a method according to any one of the possible designs or implementations of the first to third embodiments.

[0042] In one possible design, the communication device includes a processor and an interface circuit. The processor is configured to communicate with another device via the interface circuit and to perform a method according to any one of the possible designs or implementations of the first to third embodiments.

[0043] In a fourth embodiment, it will be understood that the processor may be implemented in hardware or in software. If the processor is implemented in hardware, it may be a logic circuit or an integrated circuit, etc. If the processor is implemented in software, it may be a general-purpose processor and be implemented by reading software code stored in memory. In addition, there may be one or more processors and one or more memories. The memory may be integrated with the processor, or the memory and processor may be located separately. In a specific implementation process, the memory and processor may be integrated on the same chip, or they may be located separately on separate chips. The type of memory, and the manner in which the memory and processor are arranged, are not limited to the embodiments of this application.

[0044] According to a fifth aspect, the present application provides a communication system, which may include a first communication device and a second communication device. The first communication device is configured to perform the method according to the first aspect, and the second communication device is configured to perform the method according to the second aspect and / or the third aspect.

[0045] According to the sixth aspect, the present application provides a computer-readable storage medium that stores computer-readable instructions, and when a computer reads and executes a computer-readable instruction, causes the computer to perform a method according to any one of the possible designs of the first to third aspects.

[0046] According to the seventh aspect, the present application provides a computer program product. When a computer reads and executes the computer program product, it causes the computer to perform a method according to any one of the possible designs of the first to third aspects.

[0047] According to the eighth aspect, the present application provides a chip comprising a processor, the processor being coupled to memory and configured to read and execute a software program stored in memory in order to carry out a method according to any one of the possible designs of the first to third aspects. [Brief explanation of the drawing]

[0048] [Figure 1] This is a diagram of a communication system architecture applicable to one embodiment of this application. [Figure 2A] This is a schematic flowchart of one type of random access according to one embodiment of this application. [Figure 2B] This is a schematic flowchart of another type of random access according to one embodiment of this application. [Figure 3] This is a schematic flowchart relating to a first random access according to one embodiment of this application. [Figure 4] This is a schematic flowchart relating to a second random access according to one embodiment of this application. [Figure 5] This is a schematic flowchart corresponding to the communication method according to Embodiment 1 of this application. [Figure 6] This is a schematic flowchart corresponding to the communication method according to Embodiment 2 of this application. [Figure 7] This is a possible exemplary block diagram of a device according to one embodiment of this application. [Figure 8] This is a diagram showing the structure of a communication device according to one embodiment of this application. [Modes for carrying out the invention]

[0049] The following describes the technical solutions in the embodiments of this application with reference to the accompanying drawings of the embodiments of this application. The technical solutions in the embodiments of this application may be applied to various communication systems, such as fourth-generation (4G) mobile communication systems including universal mobile telecommunications systems (UMTS), wireless local area network (WLAN) systems, wireless fidelity (Wi-Fi) systems, and long-term evolution (LTE) systems; fifth-generation (5G) mobile communication systems including new radio (NR) systems; and future advanced communication systems such as sixth-generation (6G) mobile communication systems.

[0050] In this application, all aspects, embodiments, or features are presented by describing systems that may include multiple devices, components, modules, etc. It should be understood that each system may include other devices, components, modules, etc., and / or may not include all of the devices, components, modules, etc. described with reference to the accompanying drawings. In addition, combinations of these solutions may be used. Furthermore, in embodiments of this application, terms such as “example” and “for example” are used to give examples, illustrations, or explanations. No embodiment or design scheme described as “example” in this application should be described as preferable to another embodiment or design scheme, or as having more advantages than another embodiment or design scheme. More precisely, the term “example” is used to present a concept in a concrete way. In embodiments of this application, “of,” “relevant,” and “corresponding” may be used interchangeably. It should be noted that the meanings expressed by these terms are identical unless the difference is emphasized.

[0051] To facilitate understanding of the embodiments of this application, the communication system shown in Figure 1 is used first as an example to illustrate in detail a communication system applicable to the embodiments of this application. As shown in Figure 1, the communication system 10 includes one or more network devices 20 and one or more terminals 30. The interface between the network device and the terminal may be a Uu interface (also called an air interface), and data transmission may be performed between the network device 20 and the terminal 30 over an air interface resource. For example, the terminal may be located within the communication coverage of one or more cells of the network device. There may be one or more cells providing services to the terminal (i.e., serving cells for the terminal). If there are multiple serving cells for the terminal, the terminal may operate based on one or more transmission techniques such as carrier aggregation (CA), dual connectivity (DC), coordinated multipoint (CoMP) transmission, and multiple transmission and reception point (mTRP).

[0052] (1) Terminal The terminal may also be a device having wireless transceiver functionality that accesses the aforementioned communication system. The terminal may also be called user equipment (UE), terminal device, user equipment, access terminal, subscriber unit, subscriber station, mobile station (MS), remote station, remote terminal, mobile device, user terminal, terminal unit, terminal station, terminal equipment, wireless communication device, user agent, or user equipment.

[0053] For example, the terminal in the embodiments of this application may be a mobile phone, a personal digital assistant (PDA) computer, a laptop computer, a Pad, an unmanned aerial vehicle, a computer with wireless transceiver functionality, a machine type communication (MTC) terminal, a virtual reality (VR) terminal, an augmented reality (AR) terminal, an Internet of Things (IoT) terminal, a wireless terminal in industrial control, a wireless terminal in self-driving, a wireless terminal in remote medical care, a wireless terminal in a smart grid, a wireless terminal in transportation safety, a wireless terminal in a smart city, a wireless terminal in a smart home (e.g., a game console, smart TV, smart speaker, smart refrigerator, or health device), an in-vehicle terminal, or an RSU with terminal functionality.

[0054] (2) Network devices A network device is a device with wireless transceiver functionality located on the network side of the aforementioned communication system.

[0055] For example, the network device in the embodiments of this application may be an access point (AP), base station, evolved NodeB (eNB), radio network controller (RNC), base station controller (BSC), base transceiver station (BTS), home base station, baseband unit (BBU), radio relay node, radio backhaul node, transmission and reception point (TRP), or transmission point (TP) in a Wi-Fi system, such as a home gateway, router, server, switch, or bridge. Alternatively, the network device may be a next-generation NodeB (gNB) in a 5G system, or a network node forming a gNB, such as a central unit (CU), distributed unit (DU), or roadside unit (RSU) with base station functionality, or any future form of satellite or base station.

[0056] (3) Communication between terminal and network device Communication between a terminal and a network device follows a specific protocol layer structure. For example, the control plane protocol layer structure may include the RRC layer, the packet data convergence protocol (PDCP) layer, the radio link control (RLC) layer, the media access control (MAC) layer, and the physical layer (PHY). The user plane protocol layer structure may include the PDCP layer, the RLC layer, the MAC layer, and the physical layer. In one possible implementation, a service data adaptation protocol (SDAP) layer may be further included on top of the PDCP layer. The SDAP layer, PDCP layer, RLC layer, MAC layer, and physical layer may collectively be called the access layer. For a detailed description of the protocol layers mentioned above, please refer to the relevant technical specifications of the 3rd generation partnership project (3GPP®).

[0057] Downlink data transmission is used as an example. Downlink data may be encapsulated correspondingly at each layer of the network device. Data received by a particular layer from a higher layer is considered a service data unit (SDU) for that layer, becomes a protocol data unit (PDU) through layer encapsulation, and is transmitted to the next layer. For example, data received by a PDCP layer entity from an SDAP layer may be called a PDCP SDU. After encapsulating the PDCP SDU, the PDCP layer entity retrieves the PDCP PDU and sends it to the RLC layer. The PDCP PDU received by an RLC layer entity from the PDCP layer may be called an RLC SDU. After encapsulating the RLC SDU, the RLC layer entity retrieves the RLC PDU and sends it to the MAC layer.

[0058] From the terminal's perspective, after the terminal's physical layer receives a transport block from the network device, the transport block may be sequentially transmitted from the physical layer to the higher layers, and decapsulation may be performed at each corresponding layer. In other words, the processing performed at each layer of the terminal may be the reverse process performed at each layer of the network device.

[0059] (4) CU-DU partitioned architecture For example, in some possible network architectures, a network device may include one or more central units (CUs) and / or one or more distributed units (DUs). Multiple DUs may be centrally controlled by a single CU. Such an architecture may be called a CU-DU partitioned architecture. For example, the interface between a CU and a DU may be called an F1 interface. The control plane (CP) interface may be an F1-C interface, and the user plane (UP) interface may be an F1-U interface.

[0060] The processing functions of the CU and DU may be divided based on the protocol layers of the wireless network. For example, as shown in Figure 2A, the functions of the PDCP layer and protocol layers above the PDCP layer are configured on the CU, and the functions of protocol layers below the PDCP layer (e.g., the RLC layer and MAC layer) are configured on the DU. The division of CU and DU processing functions based on protocol layers is merely an example, and it will be understood that the division may be performed alternatively in other ways. For example, the functions of protocol layers above the RLC layer are configured on the CU, and the functions of the RLC layer and protocol layers below the RLC layer are configured on the DU. As another example, the division may be performed so that the CU or DU has functions for more protocol layers. As yet another example, the division may be performed so that the CU or DU has processing functions for some of the protocol layers. This is not limited to the embodiments of this application.

[0061] Furthermore, the functions of a CU may be performed by the same entity or by different entities. For example, the functions of a CU may be further divided. Specifically, the control plane and the user plane may be separated and performed by different entities, namely, control plane CU entities (i.e., CU-CP entities) and user plane CU entities (i.e., CU-UP entities). To jointly complete the functions of a RAN device, CU-CP entities and CU-UP entities may be coupled to DUs. The interface between a CU-CP entity and a CU-UP entity may be an E1 interface, the interface between a CU-CP entity and a DU may be an F1-C interface, and the interface between a CU-UP entity and a DU may be an F1-U interface. One CU-CP may be connected to one DU and one CU-UP. Under the control of the same CU-CP, one DU may be connected to multiple CU-UPs, and one CU-UP may be connected to multiple DUs. Under the coordination of multiple CU-CPs, one CU-UP may be alternatively connected to multiple coordinating CU-CPs. This increases the flexibility of the CU-CP. Figure 2B is a diagram of the distribution of the air interface protocol stack. As shown in Figure 2B, for both the user plane and the control plane, the air interface protocol stack may have the RLC layer, MAC layer, and PHY layer on the DU, and the PDCP layer and higher protocol layer on the CU.

[0062] In the architectures shown in Figures 2A and 2B, it will be understood that signaling generated by the CU may be transmitted to the terminal via the DU, or signaling generated by the terminal may be transmitted to the CU via the DU. The DU may transparently transmit the signaling to the terminal or CU by directly encapsulating the signaling at the protocol layer without parsing the signaling. In the following embodiments, when such transmission of signaling is performed between the DU and the terminal, the transmission or reception of signaling by the DU includes such scenarios. For example, signaling at the RRC layer or PDCP layer is ultimately processed as data at the physical layer, and this data is transmitted to the terminal or transformed from data received at the physical layer. In this architecture, signaling at the RRC layer or PDCP layer may be considered to be transmitted by the DU, or by the DU and radio frequency equipment.

[0063] The communication systems and service scenarios described in the embodiments of this application are intended to more clearly illustrate the technical solutions in the embodiments of this application and do not constitute a limitation on the technical solutions provided in the embodiments of this application. With the evolution of network architectures and the emergence of new service scenarios, those skilled in the art will know that the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0064] The following sections will first describe the relevant technical features of the embodiments of this application. It should be noted that these descriptions are intended to facilitate understanding of the embodiments of this application and should not be interpreted as limitations on the scope of protection claimed in this application.

[0065] 1. Cell switch Cell switches can be classified into two types. One is a cell switch that operates on Layer 1 / Layer 2, sometimes called a Layer 1 / Layer 2 switch or Layer 1 / Layer 2 triggered mobility (L1 / L2 triggered mobility, LTM). The other is a cell handover that operates on Layer 3, sometimes called a Layer 3 handover. Layer 1 may be the physical layer, Layer 2 may be any one or more of the MAC layer, RLC layer, PDCP layer, and SDAP layer, and Layer 3 may be the RRC layer. It will be understood that a Layer 1 / Layer 2 switch may be understood alternatively as a Layer 1 and / or Layer 2 switch. When the relationship is "and", operations related to switch processing are primarily completed jointly by Layer 1 and Layer 2. When the relationship is "or", operations related to switch processing are primarily completed by Layer 1 or Layer 2. Since Layer 1 and Layer 2 are located in a lower level of the protocol stack than the RRC layer (Layer 3), a Layer 1 / Layer 2 switch may also be called a lower-layer switch.

[0066] In a Layer 3 handover, a CU-DU split architecture involves the CU receiving measurement results from the terminal (the measurement results are forwarded to the CU by the DU), determining whether to initiate a handover based on the measurement results, and if so, sending a handover command to the DU, which then sends a handover command to the terminal. This process involves communication between the CU and DU (i.e., communication over the F1 interface), with a maximum transmission delay of approximately 3ms to 10ms on the F1 interface. As a result, a specific handover delay occurs.

[0067] However, the determination of whether it is a Layer 1 or Layer 2 switch is communicated from the CU to the DU. Specifically, the DU determines whether to start the switch (LTM cell switch) based on the measurement results of the terminal and sends the switch command directly to the terminal, so that F1 communication can be effectively reduced and switch delay can be reduced.

[0068] 2. Cell Switch Scenario As mentioned above, a network device may include one or more CUs and one or more DUs. For example, a network device may include one CU and multiple DUs. Multiple DUs may be centrally controlled by the CU, and each of the multiple DUs may include one or more cells. It should be understood that "a DU includes one or more cells" may also be described as "a DU manages or controls one or more cells," "one or more cells of a DU," or "one or more cells belong to a DU."

[0069] When a terminal switches between different cells, multiple specific switch scenarios may exist. For example, a switch scenario may be obtained through classification based on the spatial relationship between the source cell and the target cell. The spatial relationship between the source cell and the target cell may be whether the source cell and the target cell belong to the same DU. Two possible switch scenarios, namely Scenario 1 and Scenario 2, are described herein.

[0070] Scenario 1: A terminal switches from one cell in a DU to another in the same DU. In other words, the terminal's source and target cells belong to the same DU. The cell switch corresponding to Scenario 1 is an intra-DU switch.

[0071] Scenario 2: A terminal switches from a cell in DU1 controlled by a CU to a cell in DU2 controlled by the same CU. In this case, DU1 may be called the source DU, and DU2 may be called the target DU. In other words, the source cell and target cell of the terminal belong to different DUs controlled by the same CU. The cell switch corresponding to Scenario 2 is an inter-DU switch.

[0072] Both intra-DU and inter-DU switches may be implemented based on Layer 1 / Layer 2 switches. In the embodiments of this application, an inter-DU switch is used as an example for illustrative purposes.

[0073] 3. Random Access Random access is the process from the transmission of a random access request by a terminal attempting to access a network to the establishment of a basic signaling connection with a network device. For example, the random access request may be a random access preamble. In the embodiments of this application, random access may also be referred to as the random access process or the random access channel (RACH) process.

[0074] Depending on whether the preamble sent by the terminal is selected by the terminal, random access may be classified as contention-based random access (CBRA) or contention-free random access (CFRA). In contention-based random access, the terminal may select a preamble. In contention-free random access, the network device may assign a preamble to the terminal.

[0075] 4. First random access and second random access A scenario in which a terminal switches from cell 1 to cell 2 is used as an example. The terminal may obtain the TA of cell 2 by initiating a first random access, or by initiating a second random access. The first random access is a random access before the switch and may be called an early random access (abbreviated as early RACH). The second random access is a random access after the switch and may be called a normal random access (abbreviated as normal RACH).

[0076] Here, a switch occasion is when a terminal receives a switch command. "Pre-switch" can be understood as "before the terminal receives a switch command," meaning that the first random access is random access that begins before the terminal receives a switch command (for example, a switch command instructing the terminal to switch to cell 2). "Post-switch" can be understood as "after the terminal receives a switch command," meaning that the second random access is random access that begins after the terminal receives a switch command (for example, a switch command instructing the terminal to switch to cell 2).

[0077] The implementation procedure for the first random access is described below with reference to Figure 3. As shown in Figure 3, the procedure may include the following steps.

[0078] S301: The terminal sends a random access request to a candidate DU in one or more candidate cells (cell 2 is used as an example).

[0079] S302: After receiving a random access request, the candidate DU sends the TA for cell 2 to the source DU.

[0080] Here, the candidate DU may measure the TA of cell 2 based on the random access request and send the TA of cell 2 to the CU, which then forwards the TA of cell 2 to the source DU.

[0081] S303: When the source DU determines that an LTM switch has started, the source DU sends a switch command to the terminal, which instructs the terminal to switch to cell 2, and the switch command includes the TA of the target cell (i.e., cell 2), and the terminal receives the switch command accordingly.

[0082] S304: The terminal transmits uplink information within cell 2 based on the TA transmitted by the switch command.

[0083] Uplink information may be transmitted over a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH).

[0084] In the procedure described above, after receiving a random access request, the candidate DU does not need to send a random access response to the terminal. In other words, after sending a random access request, the terminal may determine that the first random access is complete.

[0085] The implementation steps for the second random access method are described below with reference to Figure 4. As shown in Figure 4, the procedure may include the following steps.

[0086] S401: The source DU determines when the LTM switch has started and sends a switch command to the terminal, which instructs the terminal to switch to cell 2, and the terminal receives the switch command accordingly.

[0087] S402: The terminal, in the target cell (i.e., cell 2), sends a random access request to the target DU according to the switch command.

[0088] S403: The target DU sends a random access response to the terminal based on the random access request, the random access response includes the TA of cell 2, and the terminal receives the random access response accordingly.

[0089] S404: The terminal transmits uplink information in cell 2 based on the TA carried in the random access response.

[0090] It should be understood that Figures 3 and 4 are merely two possible procedure examples. Specific implementations may include other possible steps, and this is not limited to them.

[0091] From the description of the relevant technical features mentioned above, it can be seen that the terminal may initiate a first or second random access in order to obtain the TA of the target cell.

[0092] However, existing communication systems typically only support one type of random access, resulting in insufficient implementation flexibility.

[0093] Based on this, one embodiment of the present application provides a communication method for supporting both pre-switch and post-switch random access, thereby enabling flexible implementation of one type of random access based on actual requirements.

[0094] The communication methods provided in the embodiments of this application will be described in detail below with reference to Embodiment 1 and Embodiment 2. The communication methods provided in the embodiments of this application relate to communication between a plurality of network devices (e.g., a first network device, a second network device, and a third network device) and a terminal. Unless otherwise specified, “terminal” may refer to the terminal or to components within the terminal, such as a chip or chip system. “Network device” may refer to the network device or to components within the network device, such as a chip or chip system. For illustrative purposes, the following example will be used in which “the first network device is a CU, the second network device is a first DU managed by the CU, and the third network device is a second DU managed by the CU.”

[0095] Embodiment 1 Figure 5 is a schematic flowchart corresponding to the communication method according to Embodiment 1 of this application. As shown in Figure 5, the method includes the following steps.

[0096] S501:CU sends a first request message to the second DU, which requests the allocation of random access resources corresponding to the first random access and random access resources corresponding to the second random access.

[0097] Here, after determining the start of the LTM configuration process for the first terminal, the CU may send a first request message to the DU to which one or more candidate cells belong. The source DU to be handed over is the first DU. For example, one or more candidate cells include the first cell, and the DU to which the first cell belongs is the second DU (i.e., the second DU is the candidate DU for the first terminal). In this embodiment of the application, the first cell among a plurality of candidate cells is used as an example. The first request message sent by the CU to the second DU may be to request the second DU to allocate random access resources corresponding to the first random access and / or random access resources corresponding to the second random access in the first cell. See here for processing of other candidate cells.

[0098] For example, the first request message may be a UE context setup request message. The first request message may include request information a and request information b. Request information a is for requesting the allocation of a random access resource corresponding to a first random access, and request information b is for requesting the allocation of a random access resource corresponding to a second random access. In other words, different random access resources corresponding to different random accesses may be requested based on different request information. Alternatively, the first request message may include request information c. Request information c is for requesting the allocation of a random access resource corresponding to a first random access and a random access resource corresponding to a second random access. In other words, random access resources corresponding to different random accesses may be requested based on the same request information.

[0099] For example, the first request message may include information for identifying the first DU. The information for identifying the first DU may include at least one identifier for the first DU, an identifier for the source cell of the first terminal, and an index value, the index value being associated with the first DU and / or source cell. For example, the index value may be generated by the CU for the first DU and / or source cell.

[0100] For example, the first random access may be a random access without competition, and the second random access may be a random access based on competition, or a random access without competition. In the embodiments of this application, "both the first random access and the second random access are random access without competition" is used as an example for illustrative purposes.

[0101] S502: The second DU sends the first message to the CU, indicating that the first random access resource corresponds to the first random access and the second random access resource corresponds to the second random access, and accordingly the CU receives the first message.

[0102] In this specification, the second DU allocates a first random access resource corresponding to the first random access and a second random access resource corresponding to the second random access in the first cell based on the first request message (i.e., the first random access resource and the second random access resource are random access resources belonging to the first cell), and sends the first message to the CU.

[0103] (1) Explain the first message.

[0104] For example, the first message may be a UE context setup response message. There are multiple ways of indicating that "the first message indicates that the first random access resource corresponds to the first random access, and the second random access resource corresponds to the second random access," such as method 1 and method 2.

[0105] Instruction Method 1: The first message may include a first field corresponding to a first random access and a second field corresponding to a second random access. The first field contains first resource information, which indicates the first random access resource. The second field contains second resource information, which indicates the second random access resource. In other words, the first and second resource information are carried separately in specific fields to indicate the correspondence between random access resources and random access.

[0106] Instruction Method 2: The first message includes first resource information and instruction information a, and second resource information and instruction information b. Instruction information a indicates that the random access resource indicated by the first resource information (i.e., the first random access resource) corresponds to the first random access, and instruction information b indicates that the random access resource indicated by the second resource information (i.e., the second random access resource) corresponds to the second random access. In other words, the correspondence between random access resources and random access is indicated by the additional instruction information a and instruction information b.

[0107] (2) The first random access resource will be described.

[0108] The first random access resource may include the indices of one or more preambles and / or time-frequency resource information for carrying one or more preambles. For example, the first random access resource may include the index of one preamble and time-frequency resource information for carrying the preamble, or the first random access resource may include the indices of multiple preambles (e.g., {preamble 1, preamble 2, preamble 3}) and time-frequency resource information for carrying the multiple preambles.

[0109] For example, the first random access resource may be shared by multiple terminals. Specifically, the first random access resource is used by multiple terminals to perform the first random access, and the multiple terminals include the first terminal, and all source DUs of the multiple terminals are the first DU. For example, the first request message includes information to identify the first DU, and as a result, the second DU may assign the same first random access resource to multiple terminals of the same source DU.

[0110] For example, a first random access resource allocated by a second DU based on a first request message includes {preamble 1, preamble 2, preamble 3}. If the second DU further receives a request message sent by a CU for a second terminal, and the source DU of the second terminal is also the first DU, then the first random access resource allocated by the second DU may also include {preamble 1, preamble 2, preamble 3}.

[0111] In embodiments of this application, “multiple terminals share a first random access resource” means that multiple terminals may use the first random access resource to initiate a first random access. The source DU may indicate, based on actual requirements, that any random access resource within the first random access resource (e.g., one of preamble 1, preamble 2, or preamble 3) may be specifically used to initiate the first random access. For example, in the above example, the first random access resource includes {preamble 1, preamble 2, preamble 3}. If the first terminal and the second terminal perform the first random access simultaneously, the source DU (i.e., the first DU) may assign different preambles to the first terminal and the second terminal, for example, assigning preamble 1 to the first terminal and preamble 2 to the second terminal. If the first and second terminals perform the first random access sequentially (but not simultaneously), the first DU may assign the same preamble to both the first and second terminals. See here for other content handling related to “sharing”.

[0112] (3) The second random access resource will be described.

[0113] The second random access resource may include the indices of one or more preambles and / or time-frequency resource information for carrying one or more preambles. For example, the second random access resource may include the index of one preamble and time-frequency resource information for carrying the preamble, or the second random access resource may include the indices of multiple preambles (e.g., {preamble 4, preamble 5, preamble 6}) and time-frequency resource information for carrying the multiple preambles. The second random access resource and the first random access resource may be different random access resources.

[0114] For example, a second DU may assign a second random access resource to a first terminal. In this case, the second random access resource may be exclusive to the first terminal, i.e., it is used by the first terminal to perform the second random access. Alternatively, a second DU may assign a second random access resource to multiple terminals. In this case, the second random access resource may be shared by multiple terminals, i.e., it is used by multiple terminals to perform the second random access. The multiple terminals include the first terminal, and all source DUs for the multiple terminals are the first DU. For further details, see the description of the first random access resource.

[0115] In addition, the first message may further include other possible information, such as an identifier for the first terminal in the first cell. The identifier may be a cell radio network temporary identifier (C-RNTI).

[0116] It will be understood that S501 is an optional step. In other words, the second DU may send the first message to the CU based on the first request message, or it may proactively send the first message to the CU. S502 may also be an optional step. S502 is not necessarily performed when the CU initiates the LTM configuration process for another terminal of the first DU, and the CU obtains the first and second random access resources (shared by multiple terminals of the first DU) that were allocated by the second DU.

[0117] S503:CU sends a third message to the first DU, the third message indicating that the first random access resource corresponds to the first random access and the second random access resource corresponds to the second random access.

[0118] In this specification, after receiving the first message, the CU may, based on the third message, send the relevant information in the first message (e.g., first resource information and second resource information) to the first DU. For example, the third message may be a UE context modification request message. For specific implementations of "the third message indicating that the first random access resource corresponds to the first random access and the second random access resource corresponds to the second random access," please refer to the first message mentioned above. Further details will not be explained again.

[0119] For example, the CU may store relevant information about the first terminal, such as the source DU of the first terminal and the identifier of the first terminal in each cell (including the source cell and candidate cells). After receiving the first message, the CU may determine that the source DU of the first terminal is the first DU, based on the identifier carried in the first message, and send a third message to the first DU. In other words, when sending the first message, the second DU may not detect the first DU, but the CU identifies the first message and forwards the relevant information in the first message to the first DU.

[0120] Optionally, the third message may further include an RRC reconfiguration message. The RRC reconfiguration message may include the root sequence of the first random access preamble (referred to as root sequence 1) and the root sequence of the second random access preamble (referred to as root sequence 2). Root sequence 1 and root sequence 2 may be the same or different; this is not particularly limited. Accordingly, after receiving the third message, the first DU may send the RRC reconfiguration message from the third message to the first terminal, and the information in the third message other than the RRC reconfiguration message (e.g., first resource information and second resource information) does not need to be sent to the first terminal.

[0121] Furthermore, this method further includes S504-a to S507-a (corresponding to the first random access) or S504-b to S506-b (corresponding to the second random access). In other words, the first terminal may perform the first random access but not the second random access, or may perform the second random access but not the first random access.

[0122] S504-a: If the first terminal determines that it needs to initiate a first random access, the first DU transmits third instruction information to the first terminal, which instructs the first terminal to initiate a first random access in the first cell, and the first terminal receives the third instruction information accordingly.

[0123] This specification describes multiple implementations in which a first DU determines whether a first terminal needs to initiate a first random access. In one possible implementation, the first random access resource is shared by multiple terminals, and the first DU may determine whether a first terminal needs to initiate a first random access based on the usage of the first random access resource. For example, if the first random access resource is sufficient, the first DU may determine that a first terminal needs to initiate a first random access.

[0124] For example, the third instruction information instructs the first terminal to initiate a first random access on a first random access resource. For example, the first random access resource may be a resource set containing multiple random access resources (e.g., {preamble 1, preamble 2, preamble 3}). In this case, the third instruction information further indicates the specific resource to be used by the first terminal to initiate the first random access. For example, the third instruction information includes the index of preamble 1, i.e., instructs the first terminal to initiate the first random access using preamble 1.

[0125] In addition, there are several ways in which the first DU transmits third instruction information to the first terminal. For example, the first DU may transmit a PDCCH order to the terminal, which includes third instruction information.

[0126] S505-a: The first terminal transmits a first random access request in the first cell based on the third instruction information, and the second DU receives the first random access request accordingly.

[0127] In this specification, the first terminal may transmit a first random access request in a first cell on a first random access resource based on third instruction information. For example, if the third instruction information includes an index of preamble 1, the first terminal may generate preamble 1 based on the route sequence of the preamble for the first random access and transmit preamble 1 to the second DU in the first cell.

[0128] S506-a: The second DU determines that the first random access request corresponds to either the first random access or the second random access. If the first random access request corresponds to the first random access, it sends the TA of the first cell to the first DU, and the first DU receives the TA of the first cell accordingly.

[0129] For example, a second DU may determine the TA of the first cell based on the first random access request. In addition, the second DU may determine whether the random access resource corresponding to the first random access request is the first random access resource or the second random access resource in order to determine that the first random access request corresponds to the first random access or the second random access. In this specification, since the random access resource corresponding to the first random access request is the first random access resource, the second DU may determine that the first random access request corresponds to the first random access.

[0130] It will be understood that the second DU does not need to send a random access response to the first terminal.

[0131] For example, in this embodiment of the present application, information transmitted between the first DU and the second DU may be transferred via the CU. For example, the second DU may transmit the TA of the first cell to the first DU via the CU. For processing of other content related to communication between the first DU and the second DU, see here.

[0132] S507-a: The first DU sends a switch command to the first terminal, which instructs the first terminal to switch to the first cell, which includes the TA of the first cell, and the first terminal receives the switch command accordingly.

[0133] For example, if the first DU determines that the first terminal should be handed over to the first cell, the first DU may determine whether the TA of the first cell can be obtained through the first random access. If the TA of the first cell can be obtained through the first random access (i.e., S504-a to S506-a are performed), the first DU may send a switch command to the first terminal, which may include the identifier of the first cell (indicating that the first cell is the target cell) and the TA of the first cell.

[0134] Subsequently, the first terminal may transmit uplink information in the first cell based on the TA carried by the switch command. For details, please refer to the prior art.

[0135] S504-b: If the first terminal determines that it needs to initiate a second random access, the first DU transmits a fourth instruction to the first terminal, which instructs the first terminal to initiate a second random access in the first cell, and the first terminal receives the fourth instruction accordingly.

[0136] For example, if the first DU determines that the first terminal should be handed over to the first cell, the first DU may determine whether the first cell has a valid TA. If the first cell does not have a valid TA (for example, if the TA for the first cell is not obtained by executing S504-a to S506-a, or if the TA for the first cell is obtained by executing S504-a to S506-a, but the TA becomes invalid due to the passage of time since acquisition), the first DU determines that the first terminal needs to initiate a second random access, and sends a switch command to the first terminal, which instructs the first terminal to switch to the first cell, and the switch command may include fourth instruction information. It will be understood that an example of the fourth instruction information being carried in the switch command is used herein. In other implementations, the fourth instruction information may instead be a separate message or separate signaling. This is not particularly limited.

[0137] For example, the fourth instruction instructs the first terminal to initiate a second random access on the second random access resource. As mentioned above, the second random access resource may be a resource set containing multiple random access resources (e.g., {preamble 4, preamble 5, preamble 6}). In this case, the fourth instruction further instructs the first terminal to use a specific resource to initiate the second random access. For example, the fourth instruction includes the index of preamble 4, that is, instructs the first terminal to initiate a second random access using preamble 4.

[0138] S505-b: Based on the fourth instruction information, the first terminal sends a second random access request to the first cell on the second random access resource, and in response, the second DU receives the second random access request.

[0139] For example, if the fourth instruction information includes the index of preamble 4, the first terminal may generate preamble 4 based on the route sequence of the second random access preamble and send preamble 4 to the second DU in the first cell.

[0140] S506-b: The second DU determines that the second random access request corresponds to either the first random access or the second random access. If the second random access request corresponds to the second random access, it sends the TA of the first cell to the first terminal, and the first terminal receives the TA of the first cell accordingly.

[0141] For example, a second DU may determine the TA of the first cell based on a second random access request. In addition, the second DU may determine whether the random access resource corresponding to the second random access request is the first random access resource or the second random access resource in order to determine that the second random access request corresponds to the first random access or the second random access. In this specification, since the random access resource corresponding to the second random access request is the second random access resource, the second DU may determine that the second random access request corresponds to the second random access.

[0142] For example, the first DU may further transmit second instruction information to the second DU, the second instruction information indicating beam information for the target cell (i.e., the first cell). Furthermore, the second DU may transmit a random access response to the first terminal based on the beam information for the first cell, the random access response including the TA for the first cell. For example, the beam information for the first cell may include a synchronization signal and physical broadcast channel (PBCH) block (SSB) and / or transmission configuration indication state (TCI state) corresponding to a second random access resource (e.g., preamble 4 indicated by the fourth instruction information). For example, if the beam information for the first cell includes an SSB corresponding to a second random access resource, the second DU may transmit a random access response to the first terminal based on the SSB beam.

[0143] The first DU may further transmit fifth instruction information to the first terminal, which indicates beam information for a target cell (i.e., the first cell). Furthermore, the first terminal may receive a random access response based on the beam information for the first cell. For example, if the beam information for the first cell includes an SSB corresponding to a second random access resource, the first terminal may receive a random access response based on the SSB beam. The beam information for the target cell indicated by the second instruction information is the same as the beam information for the target cell indicated by the fifth instruction information.

[0144] For example, the fifth instruction information may be conveyed by a switch command. The sequence in which the first DU transmits the second instruction information and the switch command is not limited to this embodiment of the present application. For example, the first DU may transmit the switch command first and then the second instruction information. Or it may transmit the second instruction information first and then the switch command. Or it may transmit the second instruction information and the switch command simultaneously.

[0145] Subsequently, the first terminal may transmit uplink information in the first cell based on the TA of the first cell. For details, please refer to the prior art.

[0146] Embodiment 1 describes an example in which the second random access is a non-contour random access. In another example, the second random access in Embodiment 1 may be a conflict-based random access instead. In this case, the fourth instruction information does not need to indicate a specific resource used by the first terminal to initiate the second random access, but the first terminal may select a specific resource to be used to initiate the second random access. For related implementations of the second random access, please refer to the prior art.

[0147] According to the method described above, both pre-switch random access (i.e., first random access) and post-switch random access (i.e., second random access) are supported, and one of these types of random access can be flexibly implemented based on the actual requirements.

[0148] From the perspective of the first DU, the first random access resource corresponding to the first random access may be shared by multiple terminals of the first DU. This allows the first DU to flexibly allocate the first random access resource for use by the corresponding terminals, eliminating the need to secure a dedicated random access resource for each terminal (for example, the procedure shown in Figure 3 requires securing a dedicated random access resource for each terminal). As a result, the utilization rate of random access resources improves, allowing a large number of terminals to initiate the first random access and reducing switch delay. In the case of terminals that do not initiate the first random access, the first DU instructs the terminal to initiate the second random access to ensure the terminal's normal switching. In addition, to improve the success rate of the second random access, the second random access resource may be dedicated to the terminal.

[0149] From the perspective of the second DU, since the second DU allocates different random access resources for the first random access and the second random access, after receiving a random access request, the second DU may determine, based on the random access resource corresponding to the random access request, whether the random access request corresponds to the first or second random access, and perform the corresponding action to ensure the terminal switches correctly.

[0150] Embodiment 2 Figure 6 is a schematic flowchart corresponding to the communication method according to Embodiment 2 of this application. As shown in Figure 6, the method includes the following steps.

[0151] S601:CU sends a second request message to the second DU, which requests the allocation of random access resources corresponding to the first and second random accesses.

[0152] In Embodiment 1 described above, the first random access and the second random access correspond to different random access resources, and the first request message is for requesting the random access resources corresponding to the first random access and the random access resources corresponding to the second random access. In Embodiment 2, the first random access and the second random access correspond to the same random access resource. For the contents of S601 other than this difference, please refer to S501.

[0153] In Embodiment 2, both the first random access and the second random access may be random access without conflict.

[0154] S602: The second DU sends a second message to the CU, the second message indicating that the third random access resource corresponds to the first and second random access, and the CU receives the second message accordingly.

[0155] For example, the third random access resource may include the indices of one or more preambles and / or time-frequency resource information for carrying one or more preambles. For example, the third random access resource may include the index of one preamble and time-frequency resource information for carrying the preamble, or the third random access resource may include the indices of multiple preambles (e.g., {preamble 1, preamble 2, preamble 3, preamble 4, preamble 5, preamble 6}) and time-frequency resource information for carrying the multiple preambles.

[0156] For example, the second DU may allocate a third random access resource to multiple terminals. In this case, the third random access resource may be shared by the multiple terminals, that is, the third random access resource is used by the multiple terminals to perform the first and second random accesses. The multiple terminals include the first terminal, and all source DUs of the multiple terminals are the first DU.

[0157] There are several ways in which the second message indicates that the third random access resource corresponds to the first and second random accesses. For example, the second message may include a first field corresponding to the first random access and a second field corresponding to the second random access, both of which contain information about the third resource, and the third resource information indicates the third random access resource. In another example, the second message may include a third field corresponding to the first and second random accesses, and the third field contains information about the third resource. In yet another example, the second message may include information about the third resource and instruction information c, where instruction information c indicates that the third random access resource corresponds to the first and second random accesses.

[0158] For example, for other contents of S602, please refer to the description of S502 in Embodiment 1. For example, like the first message, the second message may be a UE context setup response message.

[0159] S603:CU sends a fourth message to the first DU, the fourth message indicating that the third random access resource corresponds to the first and second random access resources.

[0160] Furthermore, this method further includes S604-a to S607-a (corresponding to the first random access) or S604-b to S606-b (corresponding to the second random access). In other words, the first terminal may perform the first random access but not the second random access, or may perform the second random access but not the first random access.

[0161] S604-a: If the first terminal determines that it needs to initiate a first random access, the first DU transmits third instruction information to the first terminal, which instructs the first terminal to initiate a first random access in the first cell, and the first terminal receives the third instruction information accordingly.

[0162] For example, the third instruction information instructs the first terminal to initiate the first random access on the third random access resource. As described above, the third random access resource may be a set of resources containing multiple random access resources (e.g., {preamble 1, preamble 2, preamble 3, preamble 4, preamble 5, preamble 6}). In this case, the third instruction information further indicates the specific resource to be used by the first terminal to initiate the first random access. For example, the third instruction information includes the index of preamble 1, that is, instructs the first terminal to initiate the first random access using preamble 1.

[0163] S605-a: Based on the third instruction information, the first terminal sends a first random access request in the first cell on the third random access resource, and in response, the second DU receives the first random access request.

[0164] S606-a: The first DU transmits the first instruction information to the second DU, and in response, the second DU determines, based on the first instruction information, that the first random access request corresponds to the first random access.

[0165] For example, the first instruction information indicates that the third random access resource corresponds to either the first or second random access. In this step, for example, if the third random access resource includes {preamble 1, preamble 2, preamble 3, preamble 4, preamble 5, preamble 6} and time-frequency resource information for carrying the preambles, the first instruction information indicates that preamble 1 corresponds to the first random access. Furthermore, after receiving the first random access request (i.e., preamble 1), the second DU may determine that the first random access request corresponds to the first random access. For example, the first instruction information may include an identifier for the third random access resource (e.g., the index of preamble 1 and / or time-frequency resource information for carrying preamble 1).

[0166] Optionally, after receiving the first instruction information, the second DU may send feedback information to the first DU.

[0167] It will be understood that if the first terminal determines that it needs to initiate a first random access, the first DU may transmit the third instruction information and the first instruction information. The sequence in which the first DU transmits the third instruction information and the first instruction information is not limited to this embodiment of the present application. For example, S604-a, S605-a, and S606-a may be executed sequentially, or S606-a, S604-a, and S605-a may be executed sequentially, or S604-a and S606-a may be executed simultaneously, followed by S605-a.

[0168] S607-a: The second DU transmits the TA of the first cell to the first DU, and in response, the first DU receives the TA of the first cell.

[0169] S608-a: The first DU sends a switch command to the first terminal, which instructs the first terminal to switch to the first cell, which includes the TA of the first cell, and the first terminal receives the switch command accordingly.

[0170] For example, if the first DU determines that the first terminal should be handed over to the first cell, the first DU may determine whether the first cell has a valid TA. If the first cell has a valid TA (for example, if the first DU obtains the TA of the first cell by executing S604-a through S607-a), the first DU may send a switch command to the first terminal, which may include the identifier of the first cell (indicating that the first cell is the target cell) and the TA of the first cell.

[0171] Subsequently, the first terminal may transmit uplink information in the first cell based on the TA carried by the switch command. For details, please refer to the prior art.

[0172] S604-b: If the first terminal determines that it is necessary to initiate a second random access, the first DU transmits a fourth instruction to the first terminal, which instructs the first terminal to initiate a second random access in the first cell.

[0173] For example, if the first DU determines that the first terminal should be handed over to the first cell, the first DU may determine whether there is a valid TA for the first cell. If there is no valid TA for the first cell (for example, if the TA for the first cell is not obtained by executing S604-a to S607-a, or if the TA for the first cell is obtained by executing S604-a to S607-a, but the TA becomes invalid due to the passage of time since acquisition), the first DU determines that the first terminal needs to initiate a second random access, and sends a switch command to the first terminal, which instructs the first terminal to switch to the first cell, and the switch command may include fourth instruction information.

[0174] For example, the fourth instruction information instructs the first terminal to initiate a second random access on the third random access resource. As described above, the third random access resource may be a set of resources containing multiple random access resources (e.g., {preamble 1, preamble 2, preamble 3, preamble 4, preamble 5, preamble 6}). In this case, the fourth instruction information further instructs the first terminal to use a specific resource to initiate the second random access. For example, the fourth instruction information includes the index of preamble 4, that is, instructs the first terminal to initiate a second random access using preamble 4.

[0175] S605-b: The first terminal transmits a second random access request in the first cell based on the fourth instruction information, and the second DU receives the second random access request accordingly.

[0176] S606-b: The first DU transmits the first instruction information to the second DU, and in response, the second DU determines, based on the first instruction information, that the first random access request corresponds to the first random access.

[0177] For example, the first instruction information indicates that the third random access resource corresponds to either the first or second random access. In this step, for example, if the third random access resource includes {preamble 1, preamble 2, preamble 3, preamble 4, preamble 5, preamble 6}, the first instruction information indicates that preamble 4 corresponds to the second random access. Furthermore, after receiving the second random access request (i.e., preamble 2), the second DU may determine that the second random access request corresponds to the second random access. For example, the first instruction information may include an identifier for the third random access resource (e.g., the index of preamble 4 and / or time-frequency resource information for carrying preamble 4).

[0178] S607-b: The second DU sends a random access response to the first terminal, the random access response includes the TA of the first cell.

[0179] For example, the first DU may further transmit second instruction information to the second DU, the second instruction information indicating beam information of the target cell (i.e., the first cell). Furthermore, the second DU may transmit a random access response to the first terminal based on the beam information of the first cell, the random access response including the TA of the first cell.

[0180] The first DU may further transmit fifth instruction information to the first terminal, which indicates beam information for the target cell (i.e., the first cell). Furthermore, the first terminal may receive a random access response based on the beam information for the first cell, thereby improving the success rate of random access. For example, the fifth instruction information may be carried by a switch command. The beam information for the target cell indicated by the second instruction information is the same as the beam information for the target cell indicated by the fifth instruction information.

[0181] For example, the beam information of the first cell may include an SSB and / or TCI state corresponding to a third random access resource (e.g., preamble 4 indicated by the first instruction information). For example, if the beam information of the first cell includes an SSB corresponding to a second random access resource, the second DU may send a random access response to the first terminal based on the SSB beam. In response, the first terminal may receive a random access response based on the SSB beam.

[0182] According to the method described above, both pre-switch random access (i.e., first random access) and post-switch random access (i.e., second random access) are supported, and one of these types of random access can be flexibly implemented based on the actual requirements.

[0183] From the perspective of the first DU, the third random access resource may be shared by multiple terminals of the first DU. Therefore, the first DU can flexibly allocate the third random access resource to the corresponding terminal to initiate the first random access, without needing to reserve a dedicated random access resource for each terminal (for example, the procedure shown in Figure 3 requires the reservation of a dedicated random access resource for each terminal). As a result, the utilization rate of the random access resource improves, allowing a large number of terminals to initiate the first random access and reducing switch delay. For terminals that do not initiate the first random access, the first DU instructs the terminal to initiate the second random access to ensure the terminal's normal switching.

[0184] From the perspective of the second DU, the second DU may allocate a third random access resource for both the first and second random accesses, meaning that the second DU may not distinguish between the first and second random accesses when allocating random access resources. Whether the third random access resource is used specifically for the first or second random access may be flexibly determined by the first DU (source DU) or instructed by the second DU, and as a result, the second DU may, based on the instructions of the first DU, determine the random access corresponding to the random access request in order to ensure the proper switching of the terminal.

[0185] The following should be understood regarding the aforementioned embodiment.

[0186] (1) The above focuses on the differences between Embodiment 1 and Embodiment 2, and other aspects may be mutually referenced.

[0187] (2) The step numbers in each flowchart described in the embodiments above are merely examples of execution procedures and do not limit the order in which the steps are executed. In the embodiments of this application, there is no strict execution order between steps that are not chronologically dependent on each other. Not all steps shown in the flowchart are mandatory. Some steps may be removed from the flowchart based on actual requirements, or other possible steps may be added to the flowchart based on actual requirements.

[0188] (3) The message names used in the embodiments described above are examples only, and message names are not limited to the embodiments of this application. In the above description, an inter-DU switch is used as an example. The solutions in the embodiments of this application may also be extended to other scenarios. For example, the solution may be extended to intra-DU (i.e., the first DU and the second DU are the same DU). In this case, communication between the first DU and the second DU may not be included. In another example, the solution may be extended to an inter-gNB scenario (i.e., the first DU and CU belong to one gNB, and the second DU belongs to another gNB). In this case, the UE context setup request message may be replaced with a switch request message, and the UE context setup response message may be replaced with a switch response message.

[0189] The above primarily describes the solutions provided in the embodiments of this application from the perspective of the interaction between a terminal and a network device. It will be understood that in order to implement the functions described above, the terminal or network device may include corresponding hardware structures and / or software modules for performing the functions. Those skilled in the art will readily recognize, in combination with the example units and algorithmic steps described in the embodiments disclosed herein, that the embodiments of this application may be implemented in hardware or in combination of hardware and computer software. Whether the functions are performed by hardware or by hardware driven by computer software depends on the specific application and design constraints of the technical solution. Those skilled in the art may implement the functions described using various methods for each specific application, but such implementations should not be considered to exceed the scope of this application.

[0190] In embodiments of this application, the network device may be divided into functional units based on the method examples described above. For example, each functional unit may be obtained by dividing it based on each corresponding function, or two or more functions may be integrated into one unit. The integrated unit may be implemented in hardware form or in the form of a software functional unit.

[0191] When an integrated unit is used, Figure 7 is a possible exemplary block diagram of an apparatus according to one embodiment of the present application. As shown in Figure 7, the apparatus 700 may include a processing unit 702 and a communication unit 703. The processing unit 702 is configured to control and manage the operation of the apparatus 700. The communication unit 703 is configured to support the apparatus 700 in communicating with another device. Optionally, the communication unit 703, also known as a transceiver unit, may include a receiving unit configured to perform receiving operations and / or a transmitting unit configured to perform transmitting operations. The apparatus 700 may further include a storage unit 701 configured to store program code and / or data of the apparatus 700.

[0192] (1) The device 700 may be a third network device (e.g., a second DU) in the embodiments described above. The processing unit 702 supports the device 700 when performing the operations of the second DU in the method example described above. Alternatively, the processing unit 702 primarily performs the internal operations of the second DU in the method example, and the communication unit 703 supports communication between the device 700 and another device.

[0193] For example, in one embodiment, a communication unit 703 is configured to receive a random access request from a first terminal in a first cell. A processing unit 702 is configured to determine whether the random access request corresponds to a first random access or a second random access. The communication unit 703 is further configured to send a timing advance TA of the first cell to a first network device when the random access request corresponds to a first random access, or to send a TA to the first terminal when the random access request corresponds to a second random access. The first random access is a random access before the switch, and the second random access is a random access after the switch.

[0194] In one possible design, the processing unit 702 is specifically configured to determine that a random access request corresponds to a first random access if the random access resource corresponding to the random access request is a first random access resource, or to determine that a random access request corresponds to a second random access if the random access resource corresponding to the random access request is a second random access resource.

[0195] In one possible design, the communication unit 703 is further configured to send a first message to a first network device, the first message indicating that a first random access resource corresponds to a first random access and a second random access resource corresponds to a second random access.

[0196] In one possible design, the communication unit 703 is further configured to receive a first request message from a first network device, the first request message being for the allocation of random access resources corresponding to a first random access and / or random access resources corresponding to a second random access.

[0197] In one possible design, the communication unit 703 is further configured to receive first instruction information from a second network device and, based on the first instruction information, determine whether a random access request corresponds to a first random access or a second random access.

[0198] In one possible design, a random access request corresponds to a third random access resource. The processing unit 702 is specifically configured to determine that a random access request corresponds to a first random access if the first instruction information indicates that the third random access resource corresponds to a first random access, or to determine that a random access request corresponds to a second random access if the first instruction information indicates that the third random access resource corresponds to a second random access.

[0199] In one possible design, the communication unit 703 is further configured to send a second message to a first network device, the second message indicating that a third random access resource corresponds to the first and second random accesses.

[0200] In one possible design, the communication unit 703 is further configured to receive a second request message from a first network device, the second request message being for the allocation of random access resources corresponding to the first and second random accesses.

[0201] In one possible design, the communication unit 703 is further configured to receive second instruction information from a second network device, the second instruction information indicating beam information of a first cell, and based on the beam information, send a random access response to a first terminal, the random access response including a TA.

[0202] (2) The device 700 may be the second network device (e.g., the first DU) in the embodiments described above. The processing unit 702 supports the device 700 when performing the operations of the first DU in the method example described above. Alternatively, the processing unit 702 mainly performs the internal operations of the first DU in the method example, and the communication unit 703 supports communication between the device 700 and another device.

[0203] For example, in one embodiment, the communication unit 703 is configured to receive a third message from a first network device, the third message indicating that a first random access resource corresponds to a first random access and a second random access resource corresponds to a second random access. The processing unit 702 is configured to determine that a first terminal needs to initiate a first random access or a second random access. The communication unit 703 is further configured to send a third instruction to the first terminal when the first terminal needs to initiate a first random access, the third instruction instructing the first terminal to send a first random access request in a first cell on the first random access resource, and to send a fourth instruction to the first terminal when the first terminal needs to initiate a second random access, the fourth instruction instructing the first terminal to send a second random access request in a first cell on the second random access resource. The first random access is the random access before the switch, and the second random access is the random access after the switch.

[0204] In one possible design, if it is determined that the first terminal needs to initiate a first random access, the communication unit 703 is further configured to receive the TA of the first cell from the third network device, send a switch command to the first terminal, the switch command indicating that the first cell is a target cell, and the switch command includes the TA.

[0205] In one possible design, if the first terminal determines that it needs to initiate a second random access, the communication unit 703 is further configured to transmit second instruction information to a third network device, the second instruction information indicating beam information for the first cell, the beam information being used by the third network device to transmit the TA of the first cell to the first terminal.

[0206] In one possible design, if the first terminal determines that it needs to initiate a second random access, the communication unit 703 is further configured to transmit a fifth instruction to the first terminal, the fifth instruction indicating beam information of the first cell, the beam information being used by the first terminal to receive the TA of the first cell.

[0207] (3) The device 700 may be the second network device (e.g., the first DU) in the embodiments described above. The processing unit 702 supports the device 700 when performing the operations of the first DU in the method example described above. Alternatively, the processing unit 702 mainly performs the internal operations of the first DU in the method example, and the communication unit 703 supports communication between the device 700 and another device.

[0208] For example, in one embodiment, the communication unit 703 is configured to receive a fourth message from a second network device, the fourth message indicating that a third random access resource corresponds to a first random access and a second random access. The processing unit 702 is configured to determine that a first terminal needs to initiate a first random access or a second random access. The communication unit 703 is further configured to send a third instruction to the first terminal when the first terminal needs to initiate a first random access, the third instruction instructing the first terminal to send a first random access request in a first cell on the third random access resource, and to send a fourth instruction to the first terminal when the first terminal needs to initiate a second random access, the fourth instruction instructing the first terminal to send a second random access request in a first cell on the third random access resource. The first random access is a pre-switch random access, and the second random access is a post-switch random access.

[0209] In one possible design, if it is determined that the first terminal needs to initiate a first random access, the communication unit 703 is further configured to receive the TA of the first cell from the third network device, send a switch command to the first terminal, the switch command indicating that the first cell is a target cell, and the switch command includes the TA.

[0210] In one possible design, if the first terminal determines that it needs to initiate a second random access, the communication unit 703 is further configured to transmit second instruction information to a third network device, the second instruction information indicating beam information for the first cell, the beam information being used by the third network device to transmit the TA of the first cell to the first terminal.

[0211] In one possible design, if the first terminal determines that it needs to initiate a second random access, the communication unit 703 is further configured to transmit a fifth instruction to the first terminal, the fifth instruction indicating beam information of the first cell, the beam information being used by the first terminal to receive the TA of the first cell.

[0212] It should be understood that the division of units in the aforementioned device is merely a logical functional division. In actual implementation, all or part of the units may be integrated into a single physical entity or physically separated. In addition, all units in the device may be implemented in the form of software invoked by processing elements, or in the form of hardware, or some units may be implemented in the form of software invoked by processing elements, and some units may be implemented in the form of hardware. For example, each unit may be an individually located processing element, or it may be incorporated into the device's chip for implementation. In addition, each unit may be alternatively stored in memory in the form of a program to be invoked by the device's processing elements to perform the unit's function. In addition, all or part of the units may be integrated, or they may be implemented independently. The processing elements in this specification may also be called processors, and may be integrated circuits having signal processing capabilities. In the implementation process, the aforementioned methods or the operation in the aforementioned units may be implemented by using hardware integrated logic circuits within the processor element, or in the form of processing elements invoking software.

[0213] In one example, a unit in any one of the aforementioned devices may be one or more integrated circuits configured to carry out the method described above, for example, one or more application-specific integrated circuits (ASICs), one or more digital signal processors (DSPs), one or more field programmable gate arrays (FPGAs), or a combination of at least two of these forms of integrated circuits. In another example, if a unit in the device may be implemented in a manner in which a processing element schedules a program, that processing element may be a processor, for example, a general-purpose central processing unit (CPU), or another processor capable of calling a program. In yet another example, the unit may be integrated and implemented in the form of a system-on-a-chip (SoC).

[0214] The aforementioned unit configured to receive is an interface circuit of the device and is configured to receive signals from another device. For example, if the device is implemented in a chip manner, the receiving unit is an interface circuit of the chip and is configured to receive signals from another chip or device. The aforementioned unit configured to transmit is an interface circuit of the device and is configured to transmit signals to another device. For example, if the device is implemented in a chip manner, the transmitting unit is an interface circuit of the chip and is configured to transmit signals to another chip or device.

[0215] Based on the embodiments described above, one embodiment of the present application further provides a communication device. As shown in Figure 8, the communication device 800 may include a transceiver 801 and a processor 802. Optionally, the communication device 800 may further include a memory 803. The memory 803 may be located inside or outside the communication device 800. The processor 802 may control the transceiver 801 to send and receive messages and the like.

[0216] Specifically, the processor 802 may be a central processing unit (CPU), a network processor (NP), or a combination of a CPU and an NP. The processor 802 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The PLD may be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL), or any combination thereof.

[0217] The transceiver 801, processor 802, and memory 803 are connected to each other. Optionally, the transceiver 801, processor 802, and memory 803 are connected to each other via bus 804. Bus 804 may be a peripheral component interconnect (PCI) bus, an extended industry standard architecture (EISA) bus, or the like. Buses may be classified as address buses, data buses, control buses, etc. For ease of representation, only one thick line is used to represent buses in Figure 8; however, this does not mean that there is only one bus or only one type of bus.

[0218] In one optional implementation, the memory 803 is configured to store programs and the like. Specifically, the programs may include program code, and the program code may include computer operation instructions. The memory 803 may include RAM, or it may further include non-volatile memory, such as one or more magnetic disk memories. The processor 802 executes the application program stored in the memory 803 to perform the functions described above, thereby enabling the communication device 800 to function.

[0219] For example, the communication device 800 may be the first DU in the above-described embodiment, or the second DU in the above-described embodiment.

[0220] In one embodiment, when the communication device 800 performs the function of the first DU in the embodiment of the method described above, the transceiver 801 may perform the receiving and transmitting operations performed by the first DU in the embodiment of the method described above, and the processor 802 may perform operations other than the receiving and transmitting operations performed by the first DU in the embodiment of the method described above. For specific details, please refer to the relevant descriptions of the embodiments described above. Details will not be repeated here.

[0221] In another embodiment, when the communication device 800 performs the function of the second DU in the embodiment of the method described above, the transceiver 801 may perform the receiving and transmitting operations performed by the second DU in the embodiment of the method described above, and the processor 802 may perform operations other than the receiving and transmitting operations performed by the second DU in the embodiment of the method described above. For specific details, please refer to the relevant descriptions of the embodiments described above. Details will not be repeated here.

[0222] In embodiments of this application, the terms “system” and “network” may be used interchangeably. “At least one” means one or more, and “multiple” means two or more. The term “and / or” describes the relationship between related objects and indicates that three relationships may exist. For example, A and / or B may indicate the following three cases: that only A exists, that both A and B exist, and that only B exists, where A and B may be singular or plural. The symbol “ / ” generally indicates an “or” relationship between related objects. “At least one of the following items (parts)” or similar expressions refer to any combination of these items, including any combination of singular or plural items (parts). For example, “at least one of A, B, and C” includes A, B, C, AB, AC, BC, or ABC. In addition, unless otherwise specified, ordinal numbers such as “first” and “second” in embodiments of this application are used to distinguish multiple objects and are not intended to limit the order, chronological order, priority, or importance of the multiple objects.

[0223] Those skilled in the art should understand that embodiments of this application may be provided as methods, systems, or computer program products. Accordingly, this application may be provided in the form of hardware-only embodiments, software-only embodiments, or embodiments having a combination of software and hardware. In addition, this application may be provided in the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk memory, CD-ROM, optical memory, etc.) containing computer-usable program code.

[0224] This application will be described with reference to flowcharts and / or block diagrams of the methods, devices (systems), and computer program products described herein. It should be understood that computer program instructions may be used to perform each step and / or block in the flowcharts and / or block diagrams, as well as combinations of steps and / or blocks in the flowcharts and / or block diagrams. These computer program instructions may be provided to a processor of a general-purpose computer, a dedicated computer, an embedded processor, or any other programmable data processing device, and may generate a machine, as a result of instructions executed by the computer or any other programmable data processing device processor, which generates a device for performing a particular function in one or more steps in the flowchart and / or one or more blocks in the block diagram.

[0225] These computer program instructions may be stored in computer-readable memory that can be used to instruct a computer or any other programmable data processing device to act in a specific manner, and as a result, the instructions stored in computer-readable memory generate an artifact that includes an instruction unit. The instruction unit performs a specific function in one or more steps of a flowchart and / or one or more blocks of a block diagram.

[0226] Alternatively, computer program instructions may be loaded onto a computer or another programmable data processing device, resulting in a series of operations and steps being executed on the computer or another programmable device to generate a computer implementation. Thus, instructions executed on the computer or another programmable device provide steps for performing a specific function in one or more steps in a flowchart and / or one or more blocks in a block diagram.

[0227] It is clear that a person skilled in the art can make various modifications and alterations to this application without departing from the spirit and scope of this application. This application is intended to encompass such modifications and alterations, provided that they fall within the scope of protection defined by the following claims and the equivalent art. [Explanation of Symbols]

[0228] 10 Communication Systems 20 Network Devices 30 devices 700 equipment 701 Memory Unit 702 Processing Unit 703 Communication Unit 800 Communication equipment 801 Transceiver 802 Processor 803 memory 804 Bus

Claims

1. A communication method, wherein the method is The first cell receives a random access request from the first terminal, The steps include determining whether the random access request corresponds to a first random access or a second random access, When the random access request corresponds to the first random access, the step of sending the timing advance TA of the first cell to the first network device, or When the random access request corresponds to the second random access, the step of transmitting the TA to the first terminal: Includes, The first random access is the random access before the switch, and the second random access is the random access after the switch. method.

2. The step of determining whether the random access request corresponds to the first random access or the second random access is: If the random access resource corresponding to the random access request is the first random access resource, the step of determining that the random access request corresponds to the first random access, or If the random access resource corresponding to the random access request is the second random access resource, the step of determining that the random access request corresponds to the second random access. The method according to claim 1, including the method described in claim 1.

3. The aforementioned method, A step of sending a first message to the first network device, wherein the first message indicates that the first random access resource corresponds to the first random access and the second random access resource corresponds to the second random access. The method according to claim 2, further comprising:

4. The aforementioned method, Steps include receiving a first request message from the first network device, wherein the first request message is for requesting the allocation of a random access resource corresponding to the first random access and a random access resource corresponding to the second random access. The method according to claim 3, further comprising:

5. The first random access described above is a random access without competition, The first random access resource is used by multiple terminals to perform the first random access, and all of the source network devices of the multiple terminals are second network devices. The method according to any one of claims 2 to 4.

6. The second random access described above is a random access without competition, The second random access resource is used by multiple terminals to perform the second random access, and all of the source network devices of the multiple terminals are the second network device, or the second random access resource is dedicated to the first terminal. The method according to any one of claims 2 to 5.

7. The aforementioned method, The steps include receiving first instruction information from a second network device, The steps include determining, based on the first instruction information, that the random access request corresponds to the first random access or the second random access, and The method according to claim 1, further comprising:

8. The aforementioned random access request corresponds to a third random access resource, The step of determining, based on the first instruction information, that the random access request corresponds to the first random access or the second random access is: If the first instruction information indicates that the third random access resource corresponds to the first random access, the step of determining that the random access request corresponds to the first random access, or If the first instruction information indicates that the third random access resource corresponds to the second random access, the step of determining that the random access request corresponds to the second random access. The method according to claim 7, including the method described in claim 7.

9. The aforementioned method, A step of sending a second message to the first network device, wherein the second message indicates that the third random access resource corresponds to the first random access and the second random access. The method according to claim 7 or 8, further comprising:

10. The aforementioned method, Steps include receiving a second request message from the first network device, wherein the second request message is for requesting the allocation of random access resources corresponding to the first random access and the second random access. The method according to claim 9, further comprising:

11. Both the first and second random accesses are random accesses without conflicts. The third random access resource is used by multiple terminals to perform the first and second random access, and all of the source network devices of the multiple terminals are the second network device. The method according to any one of claims 7 to 10.

12. The step of transmitting the TA to the first terminal is: A step of receiving second instruction information from the second network device, wherein the second instruction information indicates beam information of the first cell, A step of transmitting a random access response to the first terminal based on the beam information, wherein the random access response includes the TA, and The method according to any one of claims 1 to 11, including the method described in any one of claims 1 to 11.

13. A communication method, wherein the method is A step of receiving a third message from a first network device, wherein the third message indicates that a first random access resource corresponds to a first random access and a second random access resource corresponds to a second random access. If it is determined that the first terminal needs to initiate the first random access, the third instruction information is transmitted to the first terminal, wherein the third instruction information instructs the first terminal to transmit a first random access request in a first cell on the first random access resource, or If the first terminal determines that it is necessary to initiate the second random access, the first terminal is sent a fourth instruction information, the fourth instruction information instructs the first terminal to send a second random access request in the first cell on the second random access resource. Includes, The first random access is the random access before the switch, and the second random access is the random access after the switch. method.

14. The first random access described above is a random access without competition, The first random access resource is used by multiple terminals to perform the first random access, and all of the source network devices of the multiple terminals are second network devices. The method according to claim 13.

15. The second random access described above is a random access without competition, The second random access resource is used by multiple terminals to perform the second random access, and all of the source network devices of the multiple terminals are the second network device, or the second random access resource is dedicated to the first terminal. The method according to claim 13 or 14.

16. A communication method, wherein the method is A step of receiving a fourth message from a second network device, wherein the fourth message indicates that a third random access resource corresponds to a first random access and a second random access. If it is determined that the first terminal needs to initiate the first random access, the first terminal is sent a third instruction information, wherein the third instruction information instructs the first terminal to send a first random access request in the first cell on the third random access resource, or If the first terminal determines that it is necessary to initiate the second random access, the first terminal is sent a fourth instruction information, the fourth instruction information instructs the first terminal to send a second random access request in the first cell on the third random access resource. Includes, The first random access is the random access before the switch, and the second random access is the random access after the switch. method.

17. Both the first and second random accesses are random accesses without conflicts. The third random access resource is used by multiple terminals to perform the first and second random access, and all of the source network devices of the multiple terminals are the second network device. The method according to claim 16.

18. The aforementioned method, Step of sending first instruction information to a third network device It further includes, If the first terminal determines that it needs to initiate the first random access, the first instruction information indicates that the third random access resource corresponds to the first random access; or if the first terminal determines that it needs to initiate the second random access, the first instruction information indicates that the third random access resource corresponds to the second random access. The method according to claim 16 or 17.

19. If it is determined that the first terminal needs to initiate the first random access, the method shall The steps include receiving the TA of the first cell from the third network device, A step of sending a switch command to the first terminal, wherein the switch command indicates that the first cell is a target cell, and the switch command includes the TA, and The method according to any one of claims 13 to 18, further comprising:

20. If it is determined that the first terminal needs to initiate the second random access, the method shall Steps of transmitting second instruction information to the third network device, wherein the second instruction information indicates beam information of the first cell, and the beam information is used by the third network device to transmit the TA of the first cell to the first terminal. The method according to any one of claims 13 to 19, further comprising:

21. If it is determined that the first terminal needs to initiate the second random access, the method shall A step of transmitting a fifth instruction information to the first terminal, wherein the fifth instruction information indicates the beam information of the first cell, and the beam information is used by the first terminal to receive the TA of the first cell. The method according to any one of claims 13 to 20, further comprising:

22. A communication device comprising a module configured to perform the method described in any one of claims 1 to 21.

23. A communication device comprising a processor, wherein the processor is coupled to a memory, the memory stores a computer program, and the processor is configured to call the computer program in the memory in order to cause the communication device to perform the method according to any one of claims 1 to 21.

24. A communication system comprising a first communication device and a second communication device, wherein the first communication device is configured to perform the method described in any one of claims 1 to 12, and the second communication device is configured to perform the method described in any one of claims 13 to 21.

25. A computer-readable storage medium, wherein the storage medium stores a computer program or instruction, and when the computer program or instruction is executed by a computer, the method according to any one of claims 1 to 21 is performed.

26. A computer program product wherein, when a computer reads and executes the computer program product, the computer executes the method according to any one of claims 1 to 21.

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