Random access method, apparatus, and communication system

Abstract

The application provides a random access method, device and communication system. The device comprises a first processing unit configured to: determine a random access type according to configuration information of a bandwidth part (BWP) selected by the terminal device for random access and downlink reference signal received power measured by the terminal device; select a random access resource; and send an initial message of random access on the random access resource.

Description

Technical Field

[0001] The embodiments of this application relate to the field of wireless communication technology. Background Technology

[0002] The random access process is a crucial step in mobile communication technology.

[0003] Figure 1 (a) is a flowchart of an existing four-step Contention Based Random Access (CBRA) process. Figure 1 As shown in (a), in operation 101, the terminal device selects a CBRA preamble and sends the preamble via Msg1 in a pre-configured contention-based random access opportunity (RO). In operation 102, after receiving the preamble, the network device sends Msg2, thereby granting the terminal device that sent the preamble a dedicated uplink PUSCH resource and allocating a temporary cell radio network temporary identifier (CRNTI) and an uplink advance indicating the physical uplink shared channel (PUSCH) in the random access response (RAR). In operation 103, the terminal device sends Msg3 carrying signaling or data on the PUSCH resource. In operation 104, the network device sends a contention resolution signaling Msg4 to the terminal device for Msg3.

[0004] Figure 1 (b) is a flowchart of an existing two-step Contention Based Random Access (CBRA) process. Figure 1 As shown in (b), in operation 105, the terminal device sends MsgA, which includes a two-step random access preamble and a data portion (payload). The terminal device sends the preamble of MsgA in a contentionable RO and sends the signaling or service data of MsgA in a contentionable Physical Uplink Shared Channel (PUSCH) resource. In operation 106, after receiving MsgA, the network device sends MsgB, thereby sending a random access response and contention resolution message to the terminal device.

[0005] It should be noted that the above introduction to the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of this application and facilitating understanding by those skilled in the art. It should not be assumed that these technical solutions are known to those skilled in the art simply because they have been described in the background section of this application. Summary of the Invention

[0006] The inventors of this application have discovered that with the advancement of technology, the types of random access are constantly increasing. Given the existence of multiple types of random access in communication standards, how to select the appropriate random access type and thus determine the appropriate random access resources has become an urgent problem to be solved.

[0007] This application provides a random access method, apparatus, and communication system. Based on the configuration information of the bandwidth portion (BWP) selected by the terminal device for random access and the downlink reference signal received power measured by the terminal device, the random access type is determined. This method can select an appropriate random access type and thus determine appropriate random access resources.

[0008] According to a first aspect of the embodiments of this application, a random access method is provided, applied to a terminal device, comprising: determining a random access type based on configuration information of a bandwidth portion (BWP) selected by the terminal device for random access and downlink reference signal received power measured by the terminal device; selecting random access resources; and sending an initial message for random access on the random access resources.

[0009] According to a second aspect of the embodiments of this application, a random access method is provided, applied to a network device, comprising: sending configuration information for random access of one or more bandwidth portions to a terminal device; wherein the configuration information includes two-step random access resources; the two-step random access resources include: a synchronization signal block (SSB) for two-step random access, a two-step random access preamble, a preamble access opportunity for two-step random access, and physical uplink shared channel (PUSCH) resources for two-step random access.

[0010] According to a third aspect of the embodiments of this application, a random access method is provided, applied to a terminal device, comprising: receiving a two-step non-contention random access resource configuration sent by a network device; and sending a first message (MsgA) of the two-step non-contention random access procedure to the network device, wherein the first message includes a two-step non-contention random access preamble and a physical uplink shared channel.

[0011] According to a fourth aspect of the embodiments of this application, a random access method is provided, applied to a network device, comprising: sending a two-step non-contention random access resource configuration to a terminal device; and receiving a first message (MsgA) of the two-step non-contention random access process from the terminal device, wherein the first message includes a two-step non-contention random access preamble and a physical uplink shared channel.

[0012] According to a fifth aspect of the embodiments of this application, a random access device is provided, which is applied to a terminal device and executes the random access methods of the first and third aspects of the embodiments of this application.

[0013] According to a sixth aspect of the embodiments of this application, a random access device is provided, which is applied to a network device and executes the random access methods of the second and fourth aspects of the embodiments of this application.

[0014] According to a seventh aspect of the present application, a terminal device is provided, which has the random access device described in the fifth aspect of the present application.

[0015] According to an eighth aspect of the embodiments of this application, a network device is provided, which has the random access device described in the sixth aspect of the embodiments of this application.

[0016] According to a ninth aspect of the embodiments of this application, a communication system is provided, which includes the terminal device described in the seventh aspect of the embodiments of this application and the network device described in the eighth aspect.

[0017] According to a tenth aspect of the present application, a computer-readable program is provided, wherein when the program is executed in a random access device or terminal device, the program causes the random access device or terminal device to perform the random access methods of the first and third aspects of the present application.

[0018] According to an eleventh aspect of the embodiments of this application, a storage medium storing a computer-readable program is provided, wherein the computer-readable program causes a random access device or terminal device to perform the random access method described in the first and third aspects of the embodiments of this application.

[0019] According to a twelfth aspect of the present application, a computer-readable program is provided, wherein when the program is executed in a random access device or network device, the program causes the random access device or network device to perform the random access method described in the second and fourth aspects of the present application.

[0020] According to a thirteenth aspect of the present application, a storage medium storing a computer-readable program is provided, wherein the computer-readable program causes a random access device or network device to perform the random access method described in the second and fourth aspects of the present application.

[0021] The beneficial effect of the embodiments of this application is that: based on the configuration information of the bandwidth portion (BWP) for random access selected by the terminal device and the downlink reference signal received power measured by the terminal device, the random access type is determined, thereby enabling the selection of an appropriate random access type and thus determining an appropriate random access resource.

[0022] Specific embodiments of this application are disclosed in detail with reference to the following description and accompanying drawings, indicating how the principles of this application can be adopted. It should be understood that the embodiments of this application are not limited in scope. Within the scope of the appended claims, embodiments of this application include many changes, modifications, and equivalents.

[0023] Features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0024] It should be emphasized that the term "including / comprises" as used herein refers to the presence of a feature, whole, step, or component, but does not exclude the presence or addition of one or more other features, wholes, steps, or components. Attached Figure Description

[0025] The elements and features described in one drawing or embodiment of this application may be combined with elements and features shown in one or more other drawings or embodiments. Furthermore, in the drawings, similar reference numerals denote corresponding parts in several drawings and can be used to indicate corresponding parts used in more than one embodiment.

[0026] The accompanying drawings, which form part of the specification, are used to provide a further understanding of the embodiments of this application and illustrate the implementation methods of this application, together with the textual description, to explain the principles of this application. Obviously, the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any creative effort. In the drawings:

[0027] Figure 1 (a) is a flowchart of an existing four-step contention-based random access procedure;

[0028] Figure 1 (b) is a flowchart of an existing two-step contention-based random access procedure;

[0029] Figure 2 (a) is a flowchart of a non-contention-based random access procedure;

[0030] Figure 2 (b) is a flowchart of a two-step non-contention-based random access process;

[0031] Figure 3 This is a schematic diagram of a communication system according to an embodiment of this application;

[0032] Figure 4 This is a schematic diagram of a random access method according to the first aspect of an embodiment of this application;

[0033] Figure 5 This is a schematic diagram of one implementation method for two-step random access resource selection;

[0034] Figure 6 This is a schematic diagram of another implementation method for two-step random access resource selection;

[0035] Figure 7 This is a schematic diagram of one implementation method for performing a four-step random access resource selection;

[0036] Figure 8 This is a schematic diagram of another implementation method for four-step random access resource selection;

[0037] Figure 9 This is a schematic diagram of one implementation method for selecting two-step non-contention-based random access resources;

[0038] Figure 10 This is a schematic diagram of a random access method according to the second aspect of an embodiment of this application;

[0039] Figure 11 This is a schematic diagram of a random access method according to a third aspect of an embodiment of this application;

[0040] Figure 12 This is a schematic diagram of a method for implementing operation 1102;

[0041] Figure 13 This is a schematic diagram of a random access method according to the fourth aspect of an embodiment of this application;

[0042] Figure 14 This is a schematic diagram of a random access device according to the fifth aspect of an embodiment of this application;

[0043] Figure 15 This is another schematic diagram of a random access device according to the fifth aspect of the embodiments of this application;

[0044] Figure 16 This is a schematic diagram of a random access device according to a sixth aspect of an embodiment of this application;

[0045] Figure 17 This is another schematic diagram of a random access device according to the sixth aspect of the embodiments of this application;

[0046] Figure 18 This is a schematic block diagram of the system configuration of the terminal device 1800 according to the seventh aspect of the present application;

[0047] Figure 19 This is a schematic diagram of the configuration of a network device according to an embodiment of this application. Detailed Implementation

[0048] Referring to the accompanying drawings, the foregoing and other features of this application will become apparent from the following description. Specific embodiments of this application are specifically disclosed in the description and drawings, illustrating partial implementations in which the principles of this application can be adopted. It should be understood that this application is not limited to the described embodiments; rather, it includes all modifications, variations, and equivalents falling within the scope of the appended claims. Various embodiments of this application are described below with reference to the accompanying drawings. These embodiments are merely exemplary and not intended to limit the scope of this application.

[0049] In the embodiments of this application, the terms "first," "second," etc., are used to distinguish different elements by name, but do not indicate the spatial arrangement or chronological order of these elements, and these elements should not be limited by these terms. The term "and / or" includes any one or more of the terms listed in association and all combinations thereof. The terms "comprising," "including," "having," etc., refer to the presence of the stated features, elements, components, or assemblies, but do not exclude the presence or addition of one or more other features, elements, components, or assemblies.

[0050] In the embodiments of this application, the singular forms "a," "the," etc., including the plural forms, should be broadly interpreted as "a kind" or "a class" rather than limited to the meaning of "an." Furthermore, the term "the" should be understood to include both the singular and plural forms, unless the context explicitly indicates otherwise. Additionally, the term "according to" should be understood as "at least partially based on...", and the term "based on" should be understood as "at least partially based on...", unless the context explicitly indicates otherwise.

[0051] In the embodiments of this application, the term "communication network" or "wireless communication network" may refer to a network that conforms to any of the following communication standards, such as Long Term Evolution (LTE), LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High-Speed ​​Packet Access (HSPA), etc.

[0052] Furthermore, communication between devices in a communication system can be carried out according to communication protocols at any stage, including but not limited to the following communication protocols: 1G (generation), 2G, 2.5G, 2.75G, 3G, 4G, 4.5G and future 5G, New Radio (NR), and / or other currently known or future communication protocols.

[0053] In the embodiments of this application, the term "network device" refers, for example, to a device in a communication system that connects a terminal device to a communication network and provides services to that terminal device. Network devices may include, but are not limited to, the following devices: base station (BS), access point (AP), transmission reception point (TRP), broadcast transmitter, mobile management entity (MME), gateway, server, radio network controller (RNC), base station controller (BSC), etc.

[0054] The term "base station" can include, but is not limited to, NodeBs (or NBs), evolved NodeBs (or eNodeBs or eNBs), and 5G base stations (gNBs), etc. It can also include Remote Radio Heads (RRHs), Remote Radio Units (RRUs), relays, or low-power nodes (e.g., femto, pico, etc.). The term "base station" can encompass some or all of its functions, and each base station can provide communication coverage to a specific geographic area. The term "cell" can refer to a base station and / or its coverage area, depending on the context in which the term is used.

[0055] In the embodiments of this application, the terms "User Equipment" (UE) or "Terminal Equipment" (TE) refer, for example, to a device that accesses a communication network and receives network services through a network device. User equipment can be fixed or mobile, and may also be referred to as a mobile station (MS), terminal, subscriber station (SS), access terminal (AT), station, etc.

[0056] User equipment may include, but is not limited to, the following devices: cellular phone, personal digital assistant (PDA), wireless modem, wireless communication device, handheld device, machine-type communication device, laptop computer, cordless phone, smartphone, smartwatch, digital camera, etc.

[0057] For example, in scenarios such as the Internet of Things (IoT), user devices can also be machines or devices used for monitoring or measurement, such as including but not limited to: machine-type communication (MTC) terminals, vehicle-mounted communication terminals, device-to-device (D2D) terminals, machine-to-machine (M2M) terminals, and so on.

[0058] In the embodiments of this application, the present invention relates to a contention-free random access (CFRA) procedure and a two-step CFRA procedure. Figure 2 (a) is a flowchart of a non-contention-based random access procedure. Figure 2 (b) is a flowchart of a two-step non-contention-based random access process.

[0059] like Figure 2 As shown in (a), the non-contention-based random access procedure may include the following operations: Operation 201, the network device configures a dedicated preamble for the terminal device via a Radio Resource Control (RRC) message or a Physical Downlink Control Channel (PDCCH) command, wherein dedicated preambles may be configured on multiple Synchronization Signal Blocks / Channel State Information (SSB / CSI); Operation 202, the terminal device selects an SSB / CSI and sends the dedicated preamble via Mag1 when initiating random access; Operation 203, after receiving the dedicated preamble, the network device sends a random access response to the terminal device via Msg2; Operation 204, the terminal device sends uplink data or signaling in the uplink grant included in the random access response.

[0060] like Figure 2 As shown in (b), the two-step non-contention-based random access procedure may include the following operations: Operation 205, the network device configures a dedicated two-step random access preamble for the terminal device via a Radio Resource Control (RRC) message or a Physical Downlink Control Channel (PDCCH) command; Operation 206, the terminal device selects SSB / CSI when initiating random access and sends the dedicated preamble and Physical Uplink Shared Channel (PUSCH) via MagA; Operation 207, the network device sends a random access response to the terminal device via MsgB. In the two-step non-contention-based random access procedure, the PUSCH and dedicated preamble are sent in operation 206, thus reducing the transmission delay of the PUSCH.

[0061] In various embodiments of this application, the dedicated two-step random access preamble can also be referred to as the two-step non-contention-based random access preamble, and the two have the same meaning.

[0062] The following examples illustrate the scenarios of embodiments of this application, but this application is not limited thereto.

[0063] Figure 3 This is a schematic diagram of a communication system according to an embodiment of this application, illustrating the case of a terminal device and a network device as examples. Figure 3 As shown, the communication system 300 may include network device 301 and terminal device 302 (for simplicity, Figure 3 (This explanation will use only one terminal device as an example.)

[0064] In this embodiment of the application, network device 301 and terminal device 302 can perform existing services or services that can be implemented in the future. For example, these services include, but are not limited to: enhanced mobile broadband (eMBB), massive machine-type communication (mMTC), and ultra-reliable and low-latency communication (URLLC), etc.

[0065] Terminal device 302 can send data to network device 301, for example, using unlicensed transmission. Network device 301 can receive data sent by one or more terminal devices 302 and send feedback information (e.g., ACK / NACK) to terminal device 302. Based on the feedback information, terminal device 302 can confirm the termination of the transmission process, or can initiate new data transmission, or can retransmit the data.

[0066] The following description uses a network device in a communication system as the receiver and a terminal device as the transmitter as an example. However, this application is not limited to this, and the transmitter and / or receiver can also be other devices. For example, this application is not only applicable to uplink unlicensed transmission between a network device and a terminal device, but also to sidelink unlicensed transmission between two terminal devices.

[0067] First aspect of the embodiment

[0068] The first aspect of this application relates to a random access method applied to a terminal device, such as terminal device 302.

[0069] Figure 4 This is a schematic diagram of a random access method according to the first aspect of an embodiment of this application, as shown below. Figure 4 As shown, the random access method may include:

[0070] Operation 401: Determine the random access type based on the configuration information of the bandwidth portion (BWP) selected by the terminal device for random access and the downlink reference signal received power measured by the terminal device;

[0071] Operation 402: Selecting random access resources; and

[0072] Operation 403: Send the initial message for random access on the random access resource.

[0073] In a first aspect of the embodiments of this application, a random access type is determined based on the configuration information of the Band Width Part (BWP) selected by the terminal device for random access and the downlink reference signal received power measured by the terminal device. Thus, an appropriate random access type can be selected and appropriate random access resources can be determined.

[0074] In operation 401, if the bandwidth portion (BWP) selected by the terminal device is configured with two-step random access resources and the downlink reference signal received power measured by the terminal device is higher than a first threshold, the random access type is determined to be two-step random access; or, if the bandwidth portion (BWP) selected by the terminal device is configured with only two-step random access resources, the random access type is determined to be two-step random access; otherwise, the random access type is determined to be four-step random access.

[0075] In at least one embodiment, in operation 401, the two-step random access resources configured in the bandwidth portion (BWP) selected by the terminal device include: a synchronization signal block (SSB) for two-step random access, a two-step random access preamble, a two-step random access preamble access opportunity, and physical uplink shared channel (PUSCH) resources for two-step random access.

[0076] In at least one embodiment, the first threshold is a measurement threshold parameter based on a synchronization signal block (SSB) configured by Radio Resource Control (RRC) signaling.

[0077] In at least one embodiment, if the serving cell is configured with different uplink carriers, the terminal uses the measurement threshold corresponding to the uplink carrier. That is, when the terminal device selects the supplementary uplink (SUL) carrier of the serving cell for random access, the first threshold is the first threshold for the supplementary uplink; when the terminal device selects the normal uplink (NUL) carrier of the serving cell for random access, the first threshold is the first threshold for the normal uplink. The first thresholds corresponding to the SUL carrier and the NUL carrier are configured by Radio Resource Control (RRC) signaling, respectively.

[0078] In at least one embodiment, after determining that the random access type is two-step random access in operation 401, two-step random access resource selection is performed in operation 402, i.e., operation 4021 is performed; after determining that the random access type is four-step random access in operation 401, four-step random access resource selection is performed in operation 402, i.e., operation 4022 is performed.

[0079] In operation 403, the initial random access message sent by the terminal device on the random access resource is either the first message MsgA or Msg1. For example, in operation 402, if the terminal device selects a two-step random access resource, it sends the first message MsgA; if it selects a four-step random access resource, it sends Msg1, which is the four-step random access preamble.

[0080] Figure 5 This is a schematic diagram of one implementation method for two-step random access resource selection, such as... Figure 5 As shown, performing a two-step random access resource selection (i.e., operation 4021) may include the following operations:

[0081] Operation 501: Determine whether the selection conditions for two-step non-contention random access resources are met. If the determination is "yes", proceed to operation 502; if the determination is "no", proceed to operation 503.

[0082] Operation 502: Select two-step non-contention-based random access to resources;

[0083] Operation 503: Select two-step competition for random access resources.

[0084] Figure 6 This is a schematic diagram of another implementation method for two-step random access resource selection, such as... Figure 6 As shown, performing a two-step random access resource selection (i.e., operation 4021) may include the following operations:

[0085] Operation 601: Determine whether the selection conditions for two-step non-contention random access resources are met. If the determination is "yes", proceed to operation 602; if the determination is "no", proceed to operation 603.

[0086] Operation 602: Select a two-step non-contention-based random access resource;

[0087] Operation 603: Determine whether the selection criteria for non-contention-based random access resources are met. If the determination is "yes", proceed to operation 604; if the determination is "no", proceed to operation 605.

[0088] Operation 604: Select non-contentionable random access resources;

[0089] Operation 605: Select two-step competition for random access resources.

[0090] It should be noted that when performing a two-step random access resource selection in operation 402, it is not guaranteed that a two-step random access resource will be selected. For example, in operation 604, a non-contention-based random access resource was selected.

[0091] Figure 7 This is a schematic diagram of one implementation method for four-step random access resource selection, such as... Figure 7 As shown, performing a four-step random access resource selection (i.e., operation 4022) may include the following operations:

[0092] Operation 701: Determine whether the selection criteria for non-contention random access resources are met. If the determination is "yes", proceed to operation 702; if the determination is "no", proceed to operation 703.

[0093] Operation 702: Select non-contention-based random access resources;

[0094] Operation 703: Select four steps to compete for random access resources.

[0095] Figure 8 This is a schematic diagram of another implementation method for four-step random access resource selection, such as... Figure 8 As shown, performing a four-step random access resource selection (i.e., operation 4022) may include the following operations:

[0096] Operation 801: Determine whether the selection conditions for two-step non-contention random access resources are met. If the determination is "yes", proceed to operation 802; if the determination is "no", proceed to operation 803.

[0097] Operation 802: Select a two-step non-contention-based random access resource;

[0098] Operation 803: Determine whether the selection criteria for non-contention-based random access resources are met. If the determination is "yes", proceed to operation 804; if the determination is "no", proceed to operation 805.

[0099] Operation 804: Select non-contentionable random access resources;

[0100] Operation 805: Select four steps to compete for random access resources.

[0101] It should be noted that when performing the four-step random access resource selection in operation 402, it is not guaranteed that a four-step random access resource will be selected. For example, in operation 804, a non-contention-based random access resource is selected, while in operations 702 and 802, two non-contention-based random access resources are selected.

[0102] In operations 501, 601, and 801 described above, the selection conditions for two-step non-contention-based random access resources are satisfied, including: the terminal device is configured with dedicated two-step random access resources by the network device, and the reference signal received power (RSRP) of at least one synchronization block (SSB) or channel state information reference signal (CSI-RS) in the dedicated two-step random access resources is higher than a second threshold. The dedicated two-step random access resources include: at least one synchronization block (SSB) or channel state information reference signal (CSI-RS) and a dedicated two-step random access preamble corresponding to the synchronization block (SSB) or channel state information reference signal (CSI-RS).

[0103] In operations 502, 602 and 802 above, select two steps for non-contention-based random access to resources. Figure 9 This is a schematic diagram illustrating one implementation of selecting a two-step non-contention-based random access resource, such as... Figure 9 As shown, the operation of selecting a two-step non-contention-based random access resource includes:

[0104] Operation 901: Select a synchronization signal block (SSB) or channel state information reference signal (CSI-RS) for transmitting a dedicated two-step random access preamble and physical uplink shared channel (PUSCH);

[0105] Operation 902: Set the two-step random access preamble to be sent to the dedicated two-step random access preamble corresponding to the Synchronization Signal Block (SSB) or Channel State Information Reference Signal (CSI-RS).

[0106] Operation 903: Determine the preamble access opportunity for the next available synchronization signal block (SSB) or channel state information reference signal (CSI-RS) corresponding to a two-step random access; and

[0107] Operation 904: Determine the uplink grant based on the preamble corresponding to the two-step random access and the physical uplink shared channel (PUSCH) corresponding to the preamble access opportunity.

[0108] In Operation 901, the terminal device selects a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) whose reference signal received power (RSRP) is higher than a second threshold.

[0109] In operation 902, if the Synchronization Signal Block (SSB) or Channel State Information Reference Signal (CSI-RS) is configured with dedicated two-step random access preambles corresponding to Group A and Group B, the terminal device selects either the dedicated two-step random access preamble for Group A or Group B based on path loss and / or the transport block size (TB size) of the first message (MsgA) of the two-step non-contention random access procedure. The Physical Uplink Shared Channel (PUSCH) modulation and coding strategies (MCS) corresponding to the dedicated two-step random access preambles for Group A and Group B are different. Therefore, the terminal device selects the PUSCH with a suitable MCS for transmission.

[0110] For example, if the path loss measured by terminal device 302 is less than the path loss threshold, and the transport block size (TB Size) of the first message (MsgA) is greater than the transport block size threshold, terminal device 302 will set the two-step random access preamble to be sent to a dedicated two-step random access preamble for group B; otherwise, it will set the two-step random access preamble to be sent to a dedicated two-step random access preamble for group A.

[0111] For example, if the path loss measured by terminal device 302 is less than the path loss threshold, terminal device 302 will set the two-step random access preamble to be sent to a dedicated two-step random access preamble for group B; otherwise, it will set the two-step random access preamble to be sent to a dedicated two-step random access preamble for group A.

[0112] The transport block size threshold can be, for example, the size of group A of random access MsgA (ra - MsgASizeGroupA). The path loss threshold can be calculated, for example, using the following formula:

[0113] Path loss threshold = PCMAX - preambleReceivedTargetPower -msgA - DeltaPreamble - messagePowerOffsetGroupB

[0114] Wherein, preambleReceivedTargetPower is the target received power of the preamble in the two-step contention random access, msgA-DeltaPreamble is the offset between the target received power of MsgA and the target received power of the preamble, messagePowerOffsetGroupB is the power offset of the selected preamble group, and PCMAX is the maximum transmit power (Pcmax) of the terminal device 302 for random access.

[0115] In Operation 904, the determined uplink grant (ULgrant) may include: modulation and coding scheme (MCS), uplink (UL) resources, or transport block size (TB size), etc.

[0116] like Figure 4 As shown, in at least one embodiment, after operation 403, the method further includes:

[0117] Operation 404: If the random access procedure is not completed, re-select random access resources (i.e., return to operation 402).

[0118] like Figure 4 As shown, operation 404 can include the following operations:

[0119] Operation 4041: Determine whether the random access procedure is complete. If the random access procedure is not complete (determined as "no"), the process returns to operation 402 to re-select random access resources.

[0120] In operation 4041, it can be determined whether random access is complete for the random access resource selected in operation 402. For example, if a two-step non-contention random access resource is selected in operation 402, then in operation 4041, incomplete random access may include: not receiving the second message (MsgB) after sending the first message (MsgA) of the two-step non-contention random access before the end of the two-step non-contention random access response window (ra-ResponseWindow2-step).

[0121] In this application, when operation 4041 returns to operation 402, it can enter operation 4021 of operation 402 or enter operation 4022 of operation 402.

[0122] like Figure 4 As shown, operation 404 may also include the following operations:

[0123] Operation 4042: If the terminal device selects a two-step random access resource, or if the random access type is two-step random access, then perform the two-step random access resource selection again (i.e., return to operation 4021 in operation 402).

[0124] In this process, the terminal device selects a two-step random access resource. For example, in operation 402, terminal device 302 selects either a two-step contention-based random access resource or a two-step non-contention-based random access resource. The random access type is two-step random access. For example, in operation 401, terminal device 302 determines the random access type to be two-step random access. Therefore, the random access resource selected by terminal device 302 in operation 4021 can be a two-step contention-based random access resource, a two-step non-contention-based random access resource, or a non-contention-based random access resource.

[0125] like Figure 4 As shown, after operation 4042, operation 404 may also include the following operations:

[0126] Operation 4043: If the random access procedure is not completed, determine whether the count value of the sent random access preamble is greater than the threshold N. If the count value of the preamble is greater than the threshold N (i.e., the determination result is "yes"), proceed to operation 4044; if the count value of the preamble is less than or equal to the threshold N (i.e., the determination result is "no"), proceed to operation 4021 to perform a two-step random access resource selection; and

[0127] Operation 4044: Set the random access type to four-step random access, and proceed to operation 4022 to select resources for four-step random access.

[0128] In operation 4043, the count value is used to record the number of times a two-step random access preamble is sent. For example, if the terminal device selects a two-step random access resource or a two-step non-contention random access resource, the count value is incremented; or, the count value is used to record the number of times the terminal device sends a preamble when it determines that the random access type is two-step random access.

[0129] By using operations 4043 and 4044, the random access type can be adjusted in a timely manner, thereby improving the efficiency of random access.

[0130] like Figure 4 As shown, operation 404 may also include the following operations:

[0131] Operation 4045: If the terminal device has selected four-step random access resources, or if the random access type is four-step random access, re-select four-step random access resources.

[0132] In this process, the terminal device selects a four-step random access resource. For example, in operation 402, terminal device 302 selects a four-step contention-based random access resource. The random access type is four-step random access. For example, in operation 401, terminal device 302 determines the random access type as four-step random access. In operation 4022, the random access resource selected by terminal device 302 can be a two-step non-contention-based random access resource, a non-contention-based random access resource, or a four-step contention-based random access resource.

[0133] like Figure 4 As shown, operation 404 may also include operation 4046 and operation 4047, which are located before operation 4042 and operation 4045.

[0134] Operations 4046 and 4047 are as follows:

[0135] Operation 4046: Determine whether there are two non-contention-based random access resources or non-contention-based random access resources that meet the selection criteria within the rollback time. If the determination is "yes" (i.e., there are non-contention-based random access resources that meet the selection criteria within the rollback time), then the random access resource selection is performed again before the rollback time ends (i.e., proceed to operation 4042 or operation 4045). If the determination is "no" (i.e., there are no non-contention-based random access resources that meet the selection criteria within the rollback time), then the random access resource selection is performed again after the rollback time ends (i.e., proceed to operation 4042 or operation 4045).

[0136] Operation 4047: Determine whether the rollback time has ended. If the determination is "yes" (i.e., the rollback time has ended), re-select random access resources (i.e., proceed to operation 4042 or operation 4045). If the determination is "no" (i.e., the rollback time has not ended), return to operation 4046.

[0137] In operation 4046, the two-step non-contention random access resource satisfies the selection criteria, for example, by providing the terminal equipment with dedicated two-step random access resources, and by providing at least one SSB or CSI-RS reference signal received power (RSRP) in the dedicated two-step random access resources to a level higher than a second threshold.

[0138] In operation 4047, the backoff time is a value randomly selected between 0 and a backoff parameter, such as the two-step random access preamble backoff parameter (PREAMBLE_BACKOFF_2-step), which is indicated, for example, by the backoff indication (BI) field in MsgB.

[0139] By using operations 4046 and 4047, if random access fails to complete, the terminal device can re-attempt random access after a random rollback period based on the network's rollback instruction. This effectively controls the network's access load and allows the terminal device to prioritize two-step non-contention random access resources or non-contention random access resources for access, thereby improving random access efficiency.

[0140] In a first aspect of the embodiments of this application, the terminal device is able to select an appropriate random access type and thus determine an appropriate random access resource, thereby improving the efficiency of random access.

[0141] Second aspect of the embodiments

[0142] The second aspect of this application relates to a random access method applied to a network device, such as network device 301.

[0143] Figure 10 This is a schematic diagram of a random access method according to the second aspect of an embodiment of this application, as shown below. Figure 10 As shown, the random access method may include:

[0144] Operation 1001: Send configuration information for random access of one or more bandwidth portions to the terminal device, wherein the configuration information includes two-step random access resources.

[0145] In Operation 1001, the two-step random access resources include: a synchronization signal block (SSB) for two-step random access, a two-step random access preamble, a two-step random access preamble access opportunity, and physical uplink shared channel (PUSCH) resources for two-step random access. These two-step random access resources can be transmitted, for example, via a system broadcast message from the RRC.

[0146] like Figure 10 As shown, the method also includes:

[0147] Operation 1002: Send a first threshold to the terminal device, which is used by the terminal device to determine the random access type.

[0148] In operation 1002, the first threshold includes the first threshold for Supplemental Uplink (SUL) or the first threshold for Normal Uplink (NUL).

[0149] like Figure 10 As shown, the method also includes:

[0150] Operation 1003: Configure dedicated two-step random access resources for the terminal device.

[0151] The dedicated two-step random access resource includes at least one synchronization signal block (SSB) or channel state information reference signal (CSI-RS) and a dedicated two-step random access preamble corresponding to the SSB or CSI-RS. The network device can configure the dedicated two-step random access preamble corresponding to the SSB or CSI-RS as either group A or group B preambles, with different MCS for the PUSCH corresponding to group A and group B preambles. For example, during handover, the network device configures at least one SSB or CSI-RS for the terminal device to access the target base station based on the terminal device's measurement signal power or quality of the target base station based on the SSB or CSI-RS; and configures the terminal device with a dedicated two-step random access preamble of group A or group B based on the terminal device's measurement signal power or quality of that SSB or CSI-RS. Because the MCS of the PUSCH corresponding to group A and group B preambles are different, it is beneficial for the terminal to use an appropriate MCS to send the PUSCH under different channel quality conditions.

[0152] like Figure 10 As shown, the method also includes:

[0153] Operation 1004: Send a second threshold to the terminal device, which is used by the terminal device to select either a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS).

[0154] In operation 1004, the Synchronization Signal Block (SSB) or Channel State Information Reference Signal (CSI-RS) is configured with dedicated two-step random access preambles corresponding to Group A and Group B. The modulation and coding strategies (MCS) of the Physical Uplink Shared Channel (PUSCH) corresponding to the dedicated two-step random access preambles of Group A and Group B are different. For example, during handover, the network device configures at least one SSB or CSI-RS for the terminal device to access the target base station based on the measured signal power or quality of the target base station by the terminal device based on SSB or CSI-RS; and configures the terminal with dedicated two-step random access preambles of Group A or Group B simultaneously. In this way, the terminal device can autonomously choose to use the random access preamble of Group A or Group B according to the situation (e.g., based on the signal quality with the target base station). Because the MCS of the PUSCH corresponding to the preambles of Group A and Group B are different, it is beneficial for the terminal to use the appropriate MCS to send the PUSCH under different conditions (e.g., under different channel quality conditions).

[0155] In a first aspect of the embodiments of this application, the terminal device can select an appropriate random access type and determine an appropriate random access resource based on information sent by the network device, thereby improving the efficiency of random access.

[0156] Third aspect of the embodiments

[0157] The third aspect of this application relates to a random access method applied to a terminal device, such as terminal device 302, wherein terminal device 302 initiates a random access request to network device 301 and receives a random access response sent by network device 301.

[0158] The random access method of the third aspect of this application relates to the operations performed by the terminal device during a two-step non-contention-based random access process.

[0159] Figure 11 This is a schematic diagram of a random access method according to a third aspect of an embodiment of this application, as shown below. Figure 11 As shown, the random access method may include:

[0160] Operation 1101: Receive two-step non-contention-based random access resource configuration sent by the network device; and

[0161] Operation 1102: Send the first message (MsgA) of the two-step non-contention random access procedure to the network device. The first message includes the two-step non-contention random access preamble and the physical uplink shared channel.

[0162] According to a third aspect of the application embodiments, the first message (MsgA) sent by the terminal device to the network device includes a two-step non-contention random access preamble and a physical uplink shared channel (PUSCH), thereby reducing the transmission latency of the physical uplink shared channel (PUSCH).

[0163] In at least one embodiment, during operation 1101, the terminal device may receive the two-step non-contention random access resource configuration via physical downlink control channel (PDCCH) or radio resource control (RRC) signaling, wherein the two-step non-contention random access resource configuration may be information for configuring two-step non-contention random access resources for the terminal device.

[0164] In at least one embodiment, the two-step non-contention random access resource includes a dedicated two-step random access resource, wherein the dedicated two-step random access resource may include: at least one synchronization block (SSB) or channel state information reference signal (CSI-RS), and a dedicated two-step random access preamble corresponding to the synchronization block (SSB) or channel state information reference signal (CSI-RS). This dedicated two-step random access preamble is the two-step non-contention random access preamble included in the first message (MsgA) in operation 1102.

[0165] Figure 12 This is a schematic diagram of a method for implementing operation 1102, as shown below. Figure 12 As shown, operation 1102 may include the following operations:

[0166] Operation 1201: Select a synchronization signal block (SSB) or channel state information reference signal (CSI-RS) for transmitting a dedicated two-step random access preamble and physical uplink shared channel (PUSCH);

[0167] Operation 1202: Set the two-step random access preamble to be sent to the dedicated two-step random access preamble corresponding to the Synchronization Signal Block (SSB) or Channel State Information Reference Signal (CSI-RS);

[0168] Operation 1203: Determine the preamble access opportunity for the next available synchronization signal block (SSB) or channel state information reference signal (CSI-RS) corresponding to a two-step random access; and

[0169] Operation 1204: Determine the uplink grant based on the preamble corresponding to the two-step random access and the physical uplink shared channel (PUSCH) corresponding to the access opportunity of that preamble; and

[0170] Operation 1205: Send the first message (MsgA) according to the uplink authorization.

[0171] Operations 1201 to 1204 are the same as operations 901 to 904, respectively.

[0172] In at least one embodiment, such as Figure 11 As shown, the random access method may further include:

[0173] Operation 1103: Received the second message (MsgB) sent by the network device, confirming successful reception of the random access response.

[0174] In at least one embodiment, the second message (MsgB) may be a timing advance command media access layer control unit (TAC MACCE) scheduled by the physical downlink control channel (PDCCH) addressed to the cell radio network temporary identifier (C-RNTI) and / or the second message (MsgB) may be a media access control layer protocol data unit (MAC PDU) scheduled by the physical downlink control channel (PDCCH) addressed to the second message radio network temporary identifier (MsgB-RNTI).

[0175] In at least one embodiment, the network device can send the second message (MsgB) after successfully demodulating the two-step non-contention-based random access preamble, or after successfully demodulating both the two-step non-contention-based random access preamble and the physical uplink shared channel. For the terminal device, if it receives the second message (MsgB) sent by the network device, it can determine that it has successfully received the random access response from the network device, that is, it can determine that the random access response has been successfully received.

[0176] like Figure 11 As shown, operation 1103 may include:

[0177] Operation 11031: If the terminal device confirms that the Media Access Control Protocol Data Unit (MAC PDU) scheduled by the Physical Downlink Control Channel (PDCCH) addressed to the Cell Radio Network Temporary Identifier (C-RNTI) has been successfully demodulated, and that the MAC PDU contains a Time Advance Command Media Access Layer Control Unit (TAC MAC CE), the terminal device confirms that the random access response has been successfully received.

[0178] In operation 11031, the timing advance command media access layer control unit (TAC MAC CE) contained in the media access control layer protocol data unit is, for example, 12 bits.

[0179] In at least one embodiment, after the terminal device sends the first message (MsgA), it can listen to the PDCCH addressed to the C-RNTI in the second message (MsgB) receive window (msgB-ResponseWindow). If it is determined that the Media Access Control Layer Protocol Data Unit (MAC PDU) scheduled by the Physical Downlink Control Channel (PDCCH) addressed to the Cell Radio Network Temporary Identifier (C-RNTI) has been successfully demodulated, and the MAC PDU contains a Time Advance Command Media Access Layer Control Unit (TAC MAC CE), then it means that the second message (MsgB) sent by the network device has been received.

[0180] like Figure 11 As shown, operation 1103 may include:

[0181] Operation 11032: It is determined that the Media Access Control Protocol Data Unit (MAC PDU) scheduled by the Physical Downlink Control Channel addressed to the Second Message Radio Network Temporary Identifier (MsgB-RNTI) has been successfully demodulated, and the Random Access Preamble Identifier (RAPID) in a sub-PDU of the MAC PDU matches the two-step non-contention random access preamble sent by the terminal device. The terminal device then determines that the random access response has been successfully received.

[0182] In operation 11032, the subprotocol data unit (subPDU) contains at least a timing advance command (TAC), which is, for example, 12 bits.

[0183] In at least one embodiment, after the terminal device sends the first message (MsgA), it can listen to the PDCCH addressed to MsgB-RNTI in the second message (MsgB-ResponseWindow). If it is determined that the Media Access Control Layer Protocol Data Unit (MAC PDU) scheduled by the Physical Downlink Control Channel addressed to the second message Radio Network Temporary Identifier (MsgB-RNTI) has been successfully demodulated, and the Random Access Preamble Identifier (RAPID) in a sub-PDU of the MAC PDU matches the two-step non-contention random access preamble sent by the terminal device, then it means that the second message (MsgB) sent by the network device has been received.

[0184] In at least one embodiment, operation 1103 may include at least one of operations 11031 and 11032. Specifically, when operation 1103 includes both operations 11031 and 11032, after the terminal device sends the first message (MsgA), it can listen to both the PDCCH addressed to C-RNTI and the PDCCH addressed to MsgB-RNTI in the second message (MsgB) receiving window (msgB-ResponseWindow). Furthermore, operations 11031 and 11032 respectively determine that the random access response was successfully received. For example, if the network device successfully demodulates the MsgA PUSCH, it sends a TAC MAC CE scheduled for the PDCCH addressed to C-RNTI to the terminal device; if it fails to demodulate the MsgA PUSCH, it sends a MAC PDU scheduled for the PDCCH addressed to MsgB-RNTI to the terminal device.

[0185] In at least one embodiment, if the network device successfully demodulates the two-step non-contention random access preamble but fails to demodulate the Physical Uplink Shared Channel (PUSCH), the network device can schedule the terminal device to retransmit the PUSCH. For example, it can schedule the PUSCH retransmission using the Physical Downlink Control Channel (PDCCH) addressed to the Cell Radio Network Temporary Identifier (C-RNTI), or it can schedule the PUSCH retransmission using the Physical Downlink Control Channel (PDCCH) addressed to the Second Message Radio Network Temporary Identifier (MsgB-RNTI). In this application, the two methods of scheduling the terminal device to retransmit the PUSCH described above can be arbitrarily combined with the two methods used in operations 11031 and 11032 to determine that the random access response has been successfully received.

[0186] like Figure 11 As shown, the random access method may further include:

[0187] Operation 1104: Receive uplink grant information in the physical downlink control channel (PDCCH) addressed to the cell radio network temporary identifier (C-RNTI), the uplink grant information being used to schedule the Hybrid Automatic Repeat Request (HARQ) process retransmission of the uplink shared channel;

[0188] Operation 1105: Send HARQ process retransmission of the Physical Uplink Shared Channel (PUSCH) according to the uplink grant.

[0189] In at least one embodiment, operation 1104 follows operation 11031. In operation 1104, after sending the first message (MsgA), the terminal device can listen to the PDCCH addressed to C-RNTI in the second message (MsgB) receive window (msgB-ResponseWindow). If it receives uplink grant information in the PDCCH and the PDCCH schedules the HARQ process of MsgA for retransmission, it indicates that the network has failed to demodulate the PUSCH of MsgA. The uplink grant information includes the uplink resources and modulation and coding scheme (MCS) used for retransmission of the Physical Uplink Shared Channel (PUSCH).

[0190] In operation 1105, the terminal device performs HARQ process retransmission of the Physical Uplink Shared Channel (PUSCH) based on the uplink grant information in operation 1104.

[0191] like Figure 11 As shown, the random access method may further include:

[0192] Operation 1106: Determine that the Media Access Control Layer Protocol Data Unit (MAC PDU) addressed to the Physical Downlink Control Channel scheduled by the Second Message Radio Network Temporary Identifier (MsgB-RNTI) has been successfully demodulated, and that the RAPID in a sub-PDU of the MAC PDU matches the two-step non-contention random access preamble sent by the terminal device, and determine that the random access response has been successfully received, wherein the sub-PDU contains at least uplink grant information;

[0193] Operation 1107: Retransmit the Physical Uplink Shared Channel (PUSCH) according to the uplink grant information in the sub-protocol data unit (subPDU).

[0194] In at least one embodiment, operation 1106 follows operation 11031. In operation 1106, after sending the first message (MsgA), the terminal device can listen for the PDCCH addressed to MsgB-RNTI in the second message (MsgB) receive window (msgB-ResponseWindow). If it is determined that the Media Access Control Protocol Data Unit (MAC PDU) scheduled by the PDCCH addressed to MsgB-RNTI has been successfully demodulated, and the random access preamble identifier (RAPID) in a sub-PDU of the MAC PDU matches the two-step non-contention random access preamble sent by the terminal device, and if the sub-PDU contains uplink grant information, it means that the network device has not successfully demodulated MsgA PUSCH and scheduled the retransmission of MsgA PUSCH through the MAC PDU. The uplink grant information includes the uplink resources and modulation and coding scheme (MCS) used for retransmission of the Physical Uplink Shared Channel (PUSCH).

[0195] In operation 1107, the terminal device retransmits the Physical Uplink Shared Channel (PUSCH) based on the uplink grant information in operation 1106.

[0196] like Figure 11As shown, in operation 1104, PUSCH retransmission is scheduled using the Physical Downlink Control Channel (PDCCH) addressed to the Cell Radio Network Temporary Identifier (C-RNTI); in operation 1106, PUSCH retransmission is scheduled using the MAC PDU scheduled using the Physical Downlink Control Channel (PDCCH) addressed to the Second Message Radio Network Temporary Identifier (MsgB-RNTI). Operations 1104 and 1106 follow operation 11031, meaning that if the terminal device determines that it has successfully received MsgB according to operation 11031, it can further perform PUSCH retransmission according to operation 1104 or operation 1106.

[0197] In this application, if the terminal device determines that it has successfully received MsgB according to operation 11032, it can further perform PUSCH retransmission.

[0198] like Figure 11 As shown, the random access method may further include:

[0199] The subprotocol data unit (subPDU) containing the timing advance command (TAC) in operations 1108 and 11032 also contains uplink grant information, and the physical uplink shared channel (PUSCH) is retransmitted based on the uplink grant information.

[0200] Operation 1108 follows operation 11032. If the sub-PDU in operation 11032 also contains uplink grant information, it means that the MAC PDU successfully demodulated in operation 11032 schedules the retransmission of PUSCH, and the terminal device performs PUSCH retransmission. This uplink grant information includes: the uplink resources and modulation and coding scheme (MCS) used for Physical Uplink Shared Channel (PUSCH) retransmission.

[0201] like Figure 11 As shown, the random access method may further include:

[0202] Operation 1109: Receive uplink grant information in the physical downlink control channel (PDCCH) addressed to the cell radio network temporary identifier (C-RNTI), the uplink grant information being used to schedule the Hybrid Automatic Repeat Request (HARQ) process retransmission of the uplink shared channel;

[0203] Operation 1110: Send HARQ process retransmission of the Physical Uplink Shared Channel (PUSCH) according to the uplink grant.

[0204] In at least one embodiment, operation 1109 follows operation 11032. In operation 1109, after sending the first message (MsgA), the terminal device can listen for the PDCCH addressed to C-RNTI in the second message (MsgB) receive window (msgB-ResponseWindow). If it receives uplink grant information in the PDCCH and the PDCCH schedules the HARQ process retransmission of the PUSCH, it means that the network device has failed to demodulate the PUSCH. The uplink grant information includes the uplink resources and modulation and coding scheme (MCS) used for retransmission of the Physical Uplink Shared Channel (PUSCH).

[0205] In operation 1110, the terminal device performs HARQ process retransmission of the Physical Uplink Shared Channel (PUSCH) based on the uplink grant information in operation 1109.

[0206] It is worth noting that in some embodiments, operations 1104 and 1106 may precede operation 11031, and operation 1109 may precede operation 11032. That is, when the terminal device receives the retransmission scheduling instruction for MsgA PUSCH from the network device, it has not yet received MsgB. The terminal device has not received the second message (MsgB), and therefore has not received the timing advance command (TAC) sent by the network device. In this case, the terminal does not send a PUSCH retransmission. For example, if the second message (msgB) is not received before operation 1104 or operation 1109, the HARQ process of the Physical Uplink Shared Channel (PUSCH) is not retransmitted according to the uplink grant information in the PDCCH; as another example, if the second message (msgB) is not received before operation 1106, the PUSCH is not retransmitted according to the uplink grant information in the MAC PDU.

[0207] In at least one embodiment, in operation 1103, if the terminal device receives not only the second message (MsgB) sent by the network device, but also a response to the Hybrid Automatic Repeat Request (HARQ) sent by the network device for the uplink shared channel, then random access is determined to be complete.

[0208] In at least one embodiment, the response to the Hybrid Automatic Repeat Request (HARQ) is a correct response to the HARQ carried by the Physical Downlink Control Channel (PDCCH); or, the response to the HARQ is new data for a HARQ process scheduled by the Physical Downlink Control Channel (PDCCH).

[0209] The random access method of the third aspect of this application will be illustrated below through four examples.

[0210] Example 1

[0211] In Example 1, MsgB is a TAC MAC CE scheduled by a PDCCH addressed to C-RNTI, and the network device schedules the PUSCH retransmission of MsgA using a PDCCH scrambled by C-RNTI.

[0212] The terminal device is operated as follows:

[0213] After the terminal device sends MsgA, it listens for the PDCCH addressed to C-RNTI in the MsgB ResponseWindow.

[0214] If a terminal device receives a PDCCH addressed to C-RNTI, successfully demodulates the MAC PDU scheduled by that PDCCH, and the MAC PDU contains a 12-bit TAC MAC CE, then the terminal device determines that the random access response was successfully received. The TAC MAC CE contains the uplink time advance command (TAC) sent by the network device to the terminal device.

[0215] If the terminal device receives a retransmission of the HARQ process of MsgA scheduled by the PDCCH (i.e., the PDCCH addressed to C-RNTI contains uplink grant information), then the terminal device will retransmit the MsgA PUSCH.

[0216] Furthermore, if the terminal device receives a PDCCH scrambled with C-RNTI to schedule a MsgA PUSCH retransmission before receiving MsgB, the terminal device discards this retransmission instruction (i.e., does not perform MsgA PUSCH retransmission) because the terminal device has not yet received the TAC sent by the network device.

[0217] The terminal device is operated as follows:

[0218] Once the network device successfully demodulates the MsgA preamble, it will send MsgB.

[0219] If the network device can only successfully demodulate the MsgA preamble but not the MsgA PUSCH, then the network device still needs to schedule the retransmission of the MsgA PUSCH using a C-RNTI scrambled PDCCH. For example, the network device can first send MsgB and then send a C-RNTI scrambled PDCCH to schedule the retransmission of the MsgA PUSCH.

[0220] If the network device is able to demodulate the uplink shared channel (i.e., MsgA PUSCH), it sends a Hybrid Automatic Repeat Request (HARQ) response to the terminal device for that uplink shared channel. The HARQ response indicates that the network device has successfully demodulated the uplink shared channel.

[0221] Example 2

[0222] In Example 2, MsgB is a TAC MAC CE scheduled by a PDCCH addressed to C-RNTI, and a Random Access Response (RAR) scheduled by a PDCCH scrambled with MsgB-RNTI. The network device schedules MsgA PUSCH retransmissions using the Random Access Response scheduled by the PDCCH scrambled with MsgB-RNTI.

[0223] The terminal device is operated as follows:

[0224] After the terminal device sends MsgA, it simultaneously listens to the PDCCH addressed to C-RNTI and the PDCCH addressed to MsgB-RNTI in the MsgB receiving window (msgB-ResponseWindow).

[0225] If the terminal device receives a PDCCH addressed to C-RNTI, successfully demodulates the MAC PDU scheduled by that PDCCH, and the MAC PDU contains a 12-bit TAC MAC CE, then the terminal device determines that the random access response was successfully received and the random access was successfully completed. The TAC MAC CE contains the uplink time advance command sent by the network device to the terminal device.

[0226] When the terminal device receives a PDCCH addressed to MsgB-RNTI, successfully demodulates the MAC PDU scheduled by that PDCCH, and finds that the RAPID in a subPDU within that MAC PDU matches the two-step non-contention random access preamble (i.e., Msg A preamble) sent by the terminal device, where the RAR in that subPDU contains at least 12 bits of TAC and UL Grant information, the terminal device determines that the random access response was successfully received. Furthermore, the terminal device retransmits the MsgA PUSCH based on the UL Grant information contained in the RAR of that subPDU, where the UL Grant information indicates the uplink resources and MCS used for the MsgA PUSCH retransmission.

[0227] The operation of network devices is as follows:

[0228] If the network device successfully demodulates the MsgA preamble and MsgA PUSCH, it sends a MAC PDU (i.e., MsgB) scheduled by a PDCCH scrambled with a TACMAC CE and scrambled by C-RNTI. It also sends a response to the Hybrid Automatic Repeat Request (HARQ) sent for the uplink shared channel, which indicates that the network device has successfully demodulated the uplink shared channel.

[0229] If the network device can only successfully demodulate the MsgA preamble but cannot successfully demodulate the PUSCH, the network device sends a random access response. This random access response is scheduled by the PDCCH scrambled by MsgB-RNTI. The ULGrant information contained in the random access response is used by the terminal device to send the MsgA PUSCH retransmission.

[0230] Example 3

[0231] In Example 3, MsgB is a random access response scheduled using a PDCCH scrambled with MsgB-RNTI. The network device schedules MsgA PUSCH retransmissions using a PDCCH scrambled with C-RNTI.

[0232] The terminal device is operated as follows:

[0233] After the terminal device sends MsgA, it listens for the PDCCH addressed to MsgB-RNTI in the MsgB receive window (msgB-ResponseWindow).

[0234] If the terminal device receives a PDCCH addressed to MsgB-RNTI, successfully demodulates the MACPDU scheduled by the PDCCH, and the RAPID in a subPDU of the MAC PDU matches the non-contention two-step random access preamble (i.e., MsgA preamble) sent by the terminal device, then the terminal device considers the random access response to be successfully received. The RAR in the subPDU contains at least 12 bits of TAC.

[0235] If the terminal device receives a retransmission of the HARQ process of MsgA scheduled by the PDCCH scrambled by C-RNTI, the terminal device will retransmit the MsgA PUSCH.

[0236] If the terminal device receives a PDCCH scrambled with C-RNTI and then receives a MsgA PUSCH retransmission instruction before receiving MsgB, the terminal device discards the retransmission instruction because the terminal device has not yet received the TAC sent by the network device.

[0237] The operation of network devices is as follows:

[0238] Once the network device successfully demodulates the MsgA preamble, it will send msgB.

[0239] If the network device can only successfully demodulate the preamble but not the MsgA PUSCH, then the network device needs to schedule a retransmission of the msgA PUSCH using a C-RNTI-scrambled PDCCH. Specifically, the network device can send msgB first and then schedule a retransmission of the msgA PUSCH.

[0240] If the network device also successfully demodulates MsgA PUSCH, it sends a response to the Hybrid Automatic Repeat Request (HARQ) sent for that uplink shared channel, the HARQ response indicating that the network device has successfully demodulated the uplink shared channel.

[0241] Example 4

[0242] In Example 4, MsgB is a random access response scheduled using a PDCCH scrambled with MsgB-RNTI. The network device schedules MsgA PUSCH retransmissions using a random access response (RAR) scheduled using a PDCCH scrambled with MsgB-RNTI.

[0243] The terminal device is operated as follows:

[0244] After the terminal device sends MsgA, it listens for the PDCCH addressed to MsgB-RNTI in the MsgB receive window (msgB-ResponseWindow).

[0245] When the terminal device receives a PDCCH addressed to MsgB-RNTI, successfully demodulates the MACPDU scheduled by that PDCCH, and the RAPID in a subPDU within that MAC PDU matches the non-contention-based two-step random access preamble (i.e., MsgA preamble) sent by the terminal device, wherein the RAR in that subPDU contains at least 12 bits of TAC, then the terminal device considers the random access response to have been successfully received. If the RAR in that subPDU contains UL Grant information (e.g., the UL Grant field is a valid value), the terminal device retransmits the MsgA PUSCH according to the UL Grant information, where the UL Grant information is used to indicate the uplink resources and MCS used for the retransmission of the MsgA PUSCH.

[0246] The operation of network devices is as follows:

[0247] If the network device successfully demodulates the MsgA preamble and MsgA PUSCH, it sends a MAC PDU (i.e., MsgB) scheduled by a PDCCH scrambled with a TACMAC CE and scrambled by C-RNTI. It also sends a response to the Hybrid Automatic Repeat Request (HARQ) sent for the uplink shared channel, which indicates that the network device has successfully demodulated the uplink shared channel.

[0248] If the network device can only successfully demodulate the preamble but not the PUSCH, it sends a random access response. This random access response is scheduled by the PDCCH scrambled by MsgB-RNTI. The random access response contains TAC and UL Grant information. The UL Grant information is used by the terminal device to retransmit the MsgA PUSCH.

[0249] According to a third aspect of the embodiments of this application, in a two-step non-contention random access process, the terminal device is able to receive an appropriate random access response and correctly perform operations such as PUSCH retransmission.

[0250] Fourth aspect of the embodiments

[0251] The fourth aspect of this application relates to a random access method applied to a network device, such as network device 301, wherein network device 301 receives a random access request sent by terminal device 301 and sends a random access response to terminal device 302.

[0252] The random access method of the fourth aspect of this application involves operations performed by a network device during a two-step non-contention-based random access process, which corresponds to the operations performed by a terminal device during a two-step non-contention-based random access process involved in the random access method of the third aspect of this application.

[0253] Figure 13 This is a schematic diagram of a random access method according to the fourth aspect of an embodiment of this application, as shown below. Figure 13 As shown, the random access method includes:

[0254] Operation 1301: Send a two-step non-contention-based random access resource configuration to the terminal device; and

[0255] Operation 1302: Receive the first message (MsgA) of the two-step non-contention random access procedure from the terminal device. The first message includes the two-step non-contention random access preamble (MsgA preamble) and the physical uplink shared channel (MsgAPUSCH).

[0256] In operation 1301, network device 301 can send a two-step non-contention-based random access resource configuration to terminal device 302 via Physical Downlink Control Channel (PDCCH) or Radio Resource Control (RRC) signaling. The two-step non-contention-based random access resource includes a dedicated two-step random access resource; the dedicated two-step random access resource includes at least one Synchronization Signal Block (SSB) or Channel State Information Reference Signal (CSI-RS), and a dedicated two-step random access preamble corresponding to the SSB or CSI-RS.

[0257] like Figure 13 As shown, the random access method also includes:

[0258] Operation 1303: Successfully demodulated the two-step non-contention-based random access preamble; and

[0259] Operation 1304: Send the second message (MsgB) to the terminal device.

[0260] like Figure 13 As shown, operation 1304 includes:

[0261] Operation 13041: Send a Physical Downlink Control Channel (PDCCH) addressed to a Cell Radio Network Temporary Trace (C-RNTI) to the terminal device and send a Media Access Control Layer Protocol Data Unit (MAC PDU) scheduled by the PDCCH, wherein the MAC PDU includes a Timed Advance Command Media Access Layer Control Unit (TAC MAC CE).

[0262] like Figure 13 As shown, operation 1304 also includes:

[0263] Operation 13042: Send a Physical Downlink Control Channel (PDCCH) addressed to the terminal device and send a MAC PDU scheduled by the PDCCH, wherein the RAPID in a sub-protocol data unit (subPDU) contained in the MAC PDU matches the two-step non-contention random access preamble, and the subPDU contains at least a timing advance command (TAC).

[0264] In at least one embodiment, the network device may send a second message (MsgB) to the terminal device using at least either operation 13041 or operation 13042. The network device may send MsgB using both operation 13041 and operation 13042; for example, if the network device demodulates the PUSCH, it may use operation 13041 to send MsgB, and if the network device does not demodulate the PUSCH, it may use operation 13042 to send MsgB.

[0265] In at least one embodiment, the network device demodulates a two-step non-contention-based random access preamble and transmits MsgB using operation 13041. If the network device demodulates the two-step non-contention-based random access preamble but fails to demodulate the Physical Uplink Shared Channel (PUSCH), it can schedule PUSCH retransmissions.

[0266] In at least one embodiment, the network device can schedule retransmission of PUSCH after operation 13041.

[0267] like Figure 13 As shown, the random access method also includes:

[0268] Operation 1305: If two steps of non-contention random access preamble are demodulated, but the uplink shared channel is not demodulated, a Physical Downlink Control Channel (PDCCH) addressed to the Cell Radio Network Temporary Identifier (C-RNTI) is sent to the terminal device. The PDCCH contains uplink grant information, which is used to schedule HARQ process retransmissions of the uplink shared channel.

[0269] Operation 1306: The terminal device receives the uplink authorization information and performs HARQ process retransmission of the uplink shared channel.

[0270] Operation 1305 can schedule PUSCH retransmissions using the Physical Downlink Control Channel (PDCCH) addressed to the Cell Radio Network Temporary Identifier (C-RNTI). For example, Figure 13 As shown, operation 1305 follows operation 13041, that is, MsgB is sent first, and then the retransmission of Msg A is scheduled.

[0271] like Figure 13 As shown, the random access method also includes:

[0272] Operation 1307: If the two-step non-contention random access preamble is successfully demodulated, but the uplink shared channel is not successfully demodulated, a Physical Downlink Control Channel (PDCCH) addressed to the second Message Radio Network Temporary Identifier (msgB-RNTI) is sent to the terminal device, and a MAC PDU scheduled by the PDCCH is sent. The RAPID in a sub-protocol data unit (subPDU) contained in the MAC PDU matches the two-step non-contention random access preamble, and the subPDU contains at least uplink grant information; and

[0273] Operation 1308: Receive the physical uplink shared channel retransmitted by the terminal device according to the uplink grant information in the subPDU.

[0274] Operation 1307 enables the scheduling of PUSCH retransmissions using MAC PDUs scheduled via the Physical Downlink Control Channel (PDCCH) addressed to the Second Message Radio Network Temporary Identifier (MsgB-RNTI).

[0275] Network devices can schedule PUSCH retransmissions using either Operation 1305 or Operation 1307.

[0276] In at least another embodiment, the network device demodulates a two-step non-contention-based random access preamble and sends MsgB using operation 13041. If the network device demodulates the two-step non-contention-based random access preamble but fails to demodulate the Physical Uplink Shared Channel (PUSCH), the network device can also schedule retransmissions of the PUSCH.

[0277] like Figure 13 As shown, the random access method also includes:

[0278] Operation 1309: Receive the physical uplink shared channel retransmitted by the terminal device according to the uplink grant information in the subPDU.

[0279] For example, if the network device demodulates the two-step non-contention random access preamble but fails to demodulate the uplink shared channel, the subPDU containing the timing advance command (TAC) in operation 13042 may also contain uplink grant information for the terminal device to retransmit the uplink shared channel (PUSCH). That is, the PUSCH retransmission is scheduled using the MAC PDU scheduled by the physical downlink control channel (PDCCH) addressed to the second message radio network temporary identifier (MsgB-RNTI). In this way, the network device can receive the physical uplink shared channel (PUSCH) retransmitted by the terminal device in operation 1309 according to the uplink grant information in the subPDU.

[0280] like Figure 13 As shown, the random access method also includes:

[0281] Operation 1310: If the network device demodulates two steps of non-contention-based random access preamble but fails to demodulate the uplink shared channel, it sends a Physical Downlink Control Channel (PDCCH) addressed to the Cell Radio Network Temporary Identifier (C-RNTI) to the terminal device. The PDCCH contains uplink grant information used to schedule HARQ process retransmissions of the uplink shared channel.

[0282] Operation 1311: Receive the HARQ process retransmission of the uplink shared channel sent by the terminal device according to the uplink authorization information.

[0283] Operation 1310 can schedule PUSCH retransmissions using the Physical Downlink Control Channel (PDCCH) addressed to the Cell Radio Network Temporary Identifier (C-RNTI). For example, Figure 13 As shown, operation 1310 follows operation 13042, that is, MsgB is sent first, and then the retransmission of Msg A is scheduled.

[0284] In at least one embodiment, in operation 1304, the network device sends a second message (MsgB) to the terminal device after successfully demodulating the two-step non-contention random access preamble and the uplink shared channel.

[0285] That is, there are two implementations of operation 1304. One is to send the second message (MsgB) to the terminal device as long as the Msg Apreamble is successfully demodulated in operation 1303. The other is to send the second message (MsgB) to the terminal device only if not only the Msg Apreamble is successfully demodulated, but also the network device is successfully demodulated to MsgA PUSCH.

[0286] In some embodiments, when an uplink shared channel is demodulated, the network device may also send a Hybrid Automatic Repeat Request (HARQ) response for that uplink shared channel to the terminal device. For example, if operation 1304 sends a second message (MsgB) to the terminal device as soon as the Msg A preamble is successfully demodulated in operation 1303, then a HARQ response for that uplink shared channel is sent to the terminal device when the uplink shared channel is demodulated.

[0287] like Figure 13 As shown, the random access method also includes:

[0288] Operation 1312: In the case of demodulating the uplink shared channel, send a response to the Hybrid Automatic Repeat Request (HARQ) sent for the uplink shared channel to the terminal device, wherein the response to the Hybrid Automatic Repeat Request (HARQ) is used to indicate that the network device has successfully demodulated the uplink shared channel.

[0289] In operation 1312, the response to the Hybrid Automatic Repeat Request (HARQ) is a correct response to the HARQ carried by the physical downlink control channel; or, the response to the HARQ is new data for a HARQ process scheduled by the physical downlink control channel.

[0290] According to a third aspect of the embodiments of this application, in a two-step non-contention-based random access process, the network device is able to send an appropriate random access response.

[0291] Fifth aspect of the embodiments

[0292] A fifth aspect of this application provides a random access device applied to a terminal device, such as terminal device 302.

[0293] Figure 14 This is a schematic diagram of a random access device according to the fifth aspect of an embodiment of this application, as shown below. Figure 14 As shown, the random access device 1400 includes a first processing unit 1401.

[0294] The first processing unit 1401 can implement the random access method described in the first aspect of the embodiments of this application. For a description of how the first processing unit 1401 implements the random access method, please refer to the description of the random access method in the first aspect of the embodiments of this application.

[0295] Figure 15 This is another schematic diagram of a random access device according to the fifth aspect of the embodiments of this application, as shown below. Figure 15 As shown, the random access device 1500 includes a third processing unit 1501.

[0296] The third processing unit 1501 can implement the random access method described in the third aspect of the embodiments of this application. For a description of how the third processing unit 1501 implements the random access method, please refer to the description of the random access method in the third aspect of the embodiments of this application.

[0297] Sixth aspect of the embodiments

[0298] A sixth aspect of this application provides a random access device applied to a network device, such as network device 301.

[0299] Figure 16 This is a schematic diagram of a random access device according to a sixth aspect of an embodiment of this application, as shown below. Figure 16 As shown, the random access device 1600 includes a second processing unit 1601.

[0300] The second processing unit 1601 can implement the random access method described in the second aspect of the embodiments of this application. For a description of how the second processing unit 1601 implements the random access method, please refer to the description of the random access method in the second aspect of the embodiments of this application.

[0301] Figure 17 This is another schematic diagram of a random access device according to the sixth aspect of the embodiments of this application, as shown below. Figure 17 As shown, the random access device 1700 includes a fourth processing unit 1701.

[0302] The fourth processing unit 1701 can implement the random access method described in the fourth aspect of the embodiments of this application. For a description of how the fourth processing unit 1701 implements the random access method, please refer to the description of the random access method in the fourth aspect of the embodiments of this application.

[0303] Seventh aspect of the embodiments

[0304] A seventh aspect of this application provides a terminal device, which includes a random access device 1400 or 1500 as described in the third aspect of the embodiments.

[0305] Figure 18 This is a schematic block diagram of the system configuration of the terminal device 1800 according to the seventh aspect of this application. Figure 18 As shown, the terminal device 1800 may include a processor 1810 and a memory 1818; the memory 1818 is coupled to the processor 1810. It is worth noting that this figure is exemplary; other types of structures may be used to supplement or replace this structure to implement telecommunications functions or other functions.

[0306] In one embodiment, the functionality of the random access device 1400 or 1500 can be integrated into the processor 1810. The processor 1810 can be configured to implement the random access method of the first aspect of the embodiments.

[0307] In another embodiment, the random access device 1400 or 1500 can be configured separately from the processor 1810. For example, the random access device 1400 or 1500 can be configured as a chip connected to the processor 1810, and the functions of the random access device 1400 or 1500 can be implemented through the control of the processor 1810.

[0308] like Figure 18 As shown, the terminal device 1800 may also include: a communication module 1830, an input unit 1840, a display 1850, and a power supply 1860. It is worth noting that the terminal device 1800 is not necessarily required to include these components. Figure 18 All components shown; in addition, the terminal device 1800 may also include Figure 18 For components not shown, please refer to existing technology.

[0309] like Figure 18 As shown, the processor 1810, sometimes also referred to as a controller or operation control, may include a microprocessor or other processor device and / or logic device, which receives input and controls the operation of various components of the terminal device 1800.

[0310] The memory 1820 may be, for example, one or more of a cache, flash memory, hard drive, removable media, volatile memory, non-volatile memory, or other suitable devices. It can store various types of data, and also stores programs for executing related information. The processor 1810 can execute the program stored in the memory 1818 to perform information storage or processing, etc. The functions of other components are similar to those in existing systems and will not be described further here. The various components of the terminal device 1800 can be implemented using dedicated hardware, firmware, software, or a combination thereof, without departing from the scope of this application.

[0311] Eighth aspect of the embodiments

[0312] An eighth aspect of this application provides a network device including a random access device 1600 or 1700 as described in the fourth aspect of the embodiments.

[0313] Figure 19 This is a schematic diagram illustrating the configuration of a network device according to an embodiment of this application. Figure 19 As shown, network device 1900 may include a processor 1910 and a memory 1920; the memory 1920 is coupled to the processor 1910. The memory 1920 can store various types of data; it also stores an information processing program 1930, which is executed under the control of the processor 1910 to receive various information sent by user equipment and to send request information to user equipment.

[0314] In one embodiment, the functionality of the random access device 1600 or 1700 can be integrated into the processor 1910. The processor 1910 can be configured to implement the random access method described in the second aspect of the embodiments of this application.

[0315] In another embodiment, the random access device 1600 or 1700 can be configured separately from the processor 1910. For example, the random access device 1600 or 1700 can be configured as a chip connected to the processor 1910, and the functions of the random access device 1600 or 1700 can be implemented through the control of the processor 1910.

[0316] In addition, such as Figure 19 As shown, network device 1900 may also include: transceiver 1940 and antenna 1950, etc.; the functions of the above components are similar to those in the prior art, and will not be described in detail here. It is worth noting that network device 1900 is not necessarily required to include... Figure 19 All components shown; in addition, network device 1900 may also include Figure 19 For components not shown, please refer to existing technology.

[0317] Ninth aspect of the embodiments

[0318] A ninth aspect of the present application also provides a communication system, including a network device as described in the eighth aspect of the embodiments and a terminal device as described in the seventh aspect of the embodiments.

[0319] The apparatus and methods described above in this application can be implemented in hardware or in combination with software. This application relates to a computer-readable program that, when executed by a logic component, enables the logic component to implement the apparatus or components described above, or to implement the various methods or steps described above. This application also relates to storage media for storing the above programs, such as hard disks, magnetic disks, optical disks, DVDs, flash memory, etc.

[0320] The methods / apparatus described in conjunction with the embodiments of this application can be directly embodied in hardware, software modules executed by a processor, or a combination of both. For example, one or more and / or combinations of one or more functional block diagrams shown in the figures can correspond to various software modules in a computer program flow, or to various hardware modules. These software modules can correspond to the various steps shown in the figures, respectively. These hardware modules can be implemented, for example, using a field-programmable gate array (FPGA) to embed these software modules.

[0321] The software module can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art. A storage medium can be coupled to the processor, enabling the processor to read information from and write information to the storage medium; or the storage medium can be an integral part of the processor. The processor and storage medium can reside in an ASIC. The software module can be stored in the memory of a mobile terminal or in a memory card that can be inserted into the mobile terminal. For example, if the device (such as a mobile terminal) uses a high-capacity MEGA-SIM card or a high-capacity flash memory device, the software module can be stored in the MEGA-SIM card or the high-capacity flash memory device.

[0322] One or more and / or one or more combinations of functional blocks described in the accompanying drawings can be implemented as a general-purpose processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, or any suitable combination thereof for performing the functions described herein. One or more and / or one or more combinations of functional blocks described in the accompanying drawings can also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in communication with a DSP, or any other such configuration.

[0323] The present application has been described above with reference to specific embodiments. However, those skilled in the art should understand that these descriptions are exemplary and not intended to limit the scope of protection of the present application. Those skilled in the art can make various modifications and variations to the present application based on its spirit and principles, and these modifications and variations are also within the scope of the present application.

[0324] Regarding the implementation methods including the above embodiments, the following notes are also disclosed:

[0325] 1. A random access method, applied to a terminal device, comprising:

[0326] The random access type is determined based on the configuration information of the bandwidth portion (BWP) selected by the terminal device for random access and the downlink reference signal received power measured by the terminal device.

[0327] Selecting random access resources; and

[0328] Send the initial message for random access on the random access resource.

[0329] 2. The method as described in Appendix 1, wherein determining the random access type based on the configuration information of the bandwidth portion selected by the terminal device and the downlink reference signal received power measured by the terminal device includes:

[0330] If the bandwidth portion (BWP) selected by the terminal device is configured with two-step random access resources and the downlink reference signal received power measured by the terminal device is higher than a first threshold, the random access type is determined to be two-step random access; or, if the bandwidth portion (BWP) selected by the terminal device is configured with only two-step random access resources, the random access type is determined to be two-step random access; otherwise, the random access type is determined to be four-step random access.

[0331] 3. The method as described in Appendix 2, wherein,

[0332] When the terminal device selects an additional uplink (SUL) carrier for random access, the first threshold is the first threshold for the additional uplink.

[0333] When the terminal device selects a normal uplink (NUL) carrier for random access, the first threshold is the first threshold of the normal uplink.

[0334] 4. The method as described in Appendix 2, wherein,

[0335] The first threshold is a measurement threshold parameter based on the synchronization signal block (SSB) configured by Radio Resource Control (RRC) signaling.

[0336] 5. The method as described in Appendix 2, wherein,

[0337] The two-step random access resources include: a synchronization signal block (SSB) for two-step random access, a two-step random access preamble, a two-step random access preamble access opportunity, and physical uplink shared channel (PUSCH) resources for two-step random access.

[0338] 6. The method as described in Appendix 2, wherein the step of performing random access resource selection includes:

[0339] After determining that the random access type is two-step random access, perform two-step random access resource selection;

[0340] After determining that the random access type is four-step random access, four-step random access resource selection is performed.

[0341] 7. The method as described in Appendix 6, wherein the step of performing the two-step random access resource selection includes:

[0342] If the selection criteria for a two-step non-contention-based random access resource are met, then the two-step non-contention-based random access resource is selected.

[0343] If the selection criteria for two-step non-contention-based random access resources are not met, then two-step contention-based random access resources will be selected.

[0344] 8. The method as described in Appendix 6, wherein the step of performing two-step random access resource selection includes:

[0345] If the selection criteria for a two-step non-contention-based random access resource are met, then the two-step non-contention-based random access resource is selected.

[0346] If the selection criteria for a two-step non-contention-based random access resource are not met, but the selection criteria for a non-contention-based random access resource are met, then the non-contention-based random access resource is selected.

[0347] If the selection criteria for two-step non-contention-based random access resources are not met, then two-step contention-based random access resources will be selected.

[0348] 9. The method as described in Appendix 6, wherein the step of performing the four-step random access resource selection includes:

[0349] If the selection criteria for non-contention-based random access resources are met, then non-contention-based random access resources are selected.

[0350] If the selection criteria for non-contention-based random access resources are not met, then a four-step contention-based random access resource selection process is selected.

[0351] 10. The method as described in Appendix 6, wherein the step of performing the four-step random access resource selection includes:

[0352] If the selection criteria for a two-step non-contention-based random access resource are met, then the two-step non-contention-based random access resource is selected.

[0353] If the selection criteria for a two-step non-contention-based random access resource are not met, but the selection criteria for a non-contention-based random access resource are met, then the non-contention-based random access resource is selected.

[0354] If the selection criteria for two-step non-contention-based random access resources are not met, then a four-step contention-based random access process is selected.

[0355] 11. The method as described in Appendix 7, 8, or 10, wherein the selection criteria for two-step non-contention-based random access resources include:

[0356] The terminal device is configured with dedicated two-step random access resources by the network device, and the reference signal received power (RSRP) of at least one synchronization block (SSB) or channel state information reference signal (CSI-RS) in the dedicated two-step random access resources is higher than the second threshold.

[0357] The dedicated two-step random access resource includes at least one synchronization signal block (SSB) or channel state information reference signal (CSI-RS) and a dedicated two-step random access preamble corresponding to the synchronization signal block (SSB) or channel state information reference signal (CSI-RS).

[0358] 12. The method as described in Appendix 7, 8, or 10, wherein the step of selecting a two-step non-contention-based random access resource includes:

[0359] Select either a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) for transmitting a dedicated two-step random access preamble and physical uplink shared channel (PUSCH);

[0360] The two-step random access preamble to be sent is set to the dedicated two-step random access preamble corresponding to the Synchronization Signal Block (SSB) or Channel State Information Reference Signal (CSI-RS).

[0361] Determine the preamble access opportunity for the next available synchronization block (SSB) or channel state information reference signal (CSI-RS) for two-step random access; and

[0362] Uplink grant is determined based on the preamble of the two-step random access and the physical uplink shared channel (PUSCH) corresponding to the preamble access opportunity.

[0363] 13. The method as described in Appendix 12, wherein the step of setting the two-step random access preamble to be transmitted as a dedicated two-step random access preamble corresponding to the Synchronization Signal Block (SSB) or Channel State Information Reference Signal (CSI-RS) includes:

[0364] If the Synchronization Signal Block (SSB) or Channel State Information Reference Signal (CSI-RS) is configured with a dedicated two-step random access preamble corresponding to Group A and Group B, then the dedicated two-step random access preamble for Group A or Group B is selected based on the path loss and / or the transport block size (TB size) of the first message (MsgA) of the two-step non-contention random access procedure.

[0365] The modulation and coding strategies (MCS) of the Physical Uplink Shared Channel (PUSCH) corresponding to the dedicated two-step random access preamble in Group A and Group B are different.

[0366] 14. The method as described in Appendix 13, wherein the step of selecting the dedicated two-step random access preamble for group A or group B based on path loss and / or the transport block size (TBsize) of MsgA includes:

[0367] If the path loss is less than the loss threshold, and / or the transport block size (TB Size) of the first message (MsgA) is greater than the transport block size threshold, the two-step random access preamble to be sent is set to the dedicated two-step random access preamble of the group B.

[0368] Otherwise, the two-step random access preamble to be sent is set to the dedicated two-step random access preamble of group A.

[0369] 15. The method as described in any one of Appendices 1-14, wherein after the step of sending the initial message for random access on the random access resource, the method further comprises:

[0370] If the random access process is not completed, a new random access resource selection process will be performed.

[0371] 16. The method as described in Appendix 15, wherein,

[0372] If the terminal device selects a two-step random access resource, or if the random access type is two-step random access:

[0373] If the random access process fails to complete successfully, the two-step random access resource selection will be repeated.

[0374] 17. The method as described in Appendix 16, wherein,

[0375] If the random access procedure fails to complete successfully, and the count value of the sent random access preamble is greater than the threshold N:

[0376] The random access type is set to four-step random access, and four-step random access resource selection is performed.

[0377] 18. The method as described in Appendix 15, wherein,

[0378] If the terminal selects a four-step random access resource, or if the random access type is four-step random access:

[0379] If random access fails to complete, repeat the four-step random access resource selection process.

[0380] 19. The method as described in Appendix 16 or 18, wherein,

[0381] The step of re-selecting random access resources includes:

[0382] If it is determined that two steps of non-contention-based random access resources meet the selection criteria within the rollback time, or if any non-contention-based random access resources meet the selection criteria, then random access resource selection will be performed again before the end of the rollback time; otherwise, random access resource selection will be performed again after the end of the rollback time.

[0383] 20. The method as described in Appendix 15, wherein if a two-step non-contention-based random access resource is selected, the incomplete random access includes:

[0384] After sending the first message (MsgA) of the two-step non-contention-based random access, the second message (MsgB) was not received before the end of the two-step random access response window (ra-ResponseWindow2-step).

[0385] 21. A random access method, applied to a network device, comprising:

[0386] Send configuration information for random access of one or more bandwidth portions to the terminal device; wherein, the configuration information includes two-step random access resources;

[0387] The two-step random access resources include: a synchronization signal block (SSB) for two-step random access, a two-step random access preamble, a two-step random access preamble access opportunity, and physical uplink shared channel (PUSCH) resources for two-step random access.

[0388] 22. The method of claim 21, wherein the method further comprises:

[0389] A first threshold is sent to the terminal device, and the first threshold is used by the terminal device to determine the random access type.

[0390] 23. The method of claim 22, wherein the first threshold includes a first threshold for an additional uplink (SUL) or a first threshold for a normal uplink.

[0391] 24. The method of claim 21, wherein the method further comprises:

[0392] Configure dedicated two-step random access resources for the terminal device;

[0393] The dedicated two-step random access resource includes at least one synchronization signal block (SSB) or channel state information reference signal (CSI-RS) and a dedicated two-step random access preamble corresponding to the synchronization signal block (SSB) or channel state information reference signal (CSI-RS).

[0394] 25. The method as described in Appendix 24, wherein the method further comprises:

[0395] A second threshold is sent to the terminal device, the second threshold being used by the terminal device to select either a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS).

[0396] 26. The method of claim 24, wherein,

[0397] The synchronization signal block (SSB) or channel state information reference signal (CSI-RS) is configured with dedicated two-step random access preambles corresponding to group A and group B.

[0398] The modulation and coding strategies (MCS) of the Physical Uplink Shared Channel (PUSCH) corresponding to the dedicated two-step random access preamble in Group A and Group B are different.

[0399] 27. A random access method, applied to a terminal device, comprising:

[0400] Receive two-step non-contention-based random access resource configuration sent by the network device; and

[0401] Send a first message (MsgA) of the two-step non-contention random access procedure to the network device. The first message includes a two-step non-contention random access preamble and a physical uplink shared channel.

[0402] 28. The method as described in Appendix 27, wherein,

[0403] The terminal device receives the two-step non-contention random access resource configuration via Physical Downlink Control Channel (PDCCH) or Radio Resource Control (RRC) signaling.

[0404] 29. The method as described in Appendix 27, wherein,

[0405] The two-step non-contention-based random access resource includes dedicated two-step random access resources.

[0406] The dedicated two-step random access resource includes at least one synchronization signal block (SSB) or channel state information reference signal (CSI-RS), and a dedicated two-step random access preamble corresponding to the synchronization signal block (SSB) or channel state information reference signal (CSI-RS).

[0407] 30. The method as described in Appendix 27, wherein sending the first message (MsgA) of the two-step non-contention-based random access procedure to the network device includes:

[0408] Select either a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) for transmitting a dedicated two-step random access preamble and physical uplink shared channel (PUSCH);

[0409] The two-step random access preamble to be sent is set to the dedicated two-step random access preamble corresponding to the Synchronization Signal Block (SSB) or Channel State Information Reference Signal (CSI-RS).

[0410] Determine the preamble access opportunity for the next available synchronization signal block (SSB) or channel state information reference signal (CSI-RS) for two-step random access;

[0411] Uplink grant is determined based on the preamble corresponding to the two-step random access and the physical uplink shared channel (PUSCH) corresponding to the preamble access opportunity; and

[0412] The first message (MsgA) is sent according to the uplink authorization.

[0413] 31. The method as described in Appendix 27, wherein the method further comprises:

[0414] Upon receiving the second message (MsgB) from the network device, it is confirmed that the random access response was successfully received.

[0415] 32. The method as described in Appendix 31, wherein receiving the second message (MsgB) sent by the network device to determine that the random access response was successfully received includes:

[0416] The terminal device determines that the Media Access Control Layer Protocol Data Unit (MAC PDU) scheduled by the Physical Downlink Control Channel (PDCCH) addressed to the Cell Radio Network Temporary Identifier (C-RNTI) has been successfully demodulated, and that the MAC PDU contains a Timed Advance Command Media Access Layer Control Unit (TAC MAC CE). The terminal device then determines that the random access response has been successfully received.

[0417] 33. The method as described in Appendix 32, wherein the method further comprises:

[0418] Receive uplink grant information in the Physical Downlink Control Channel (PDCCH) addressed to the Cell Radio Network Temporary Identifier (C-RNTI), the uplink grant information being used to schedule the Hybrid Automatic Repeat Request (HARQ) process retransmission of the uplink shared channel; and

[0419] HARQ retransmission of the uplink shared channel is performed based on the uplink authorization information.

[0420] 34. The method as described in Appendix 32, wherein the method further comprises:

[0421] The Media Access Control Layer Protocol Data Unit (MAC PDU) successfully demodulated to address the Physical Downlink Control Channel scheduled by the Second Message Radio Network Temporary Identifier (MsgB-RNTI), and the RAPID in a sub-PDU of the MAC PDU matches the two-step non-contention random access preamble sent by the terminal device, wherein the sub-PDU contains at least uplink grant information.

[0422] 35. The method as described in Appendix 34, wherein the method further comprises:

[0423] The physical uplink shared channel is retransmitted according to the uplink grant information in the sub-protocol data unit (subPDU).

[0424] 36. The method as described in Appendix 31, wherein receiving the second message (MsgB) sent by the network device to determine that the random access response was successfully received includes:

[0425] If it is confirmed that a Media Access Control Protocol Data Unit (MAC PDU) addressed to the Physical Downlink Control Channel (PLC) of the Second Message Radio Network Temporary Identifier (MsgB-RNTI) has been successfully demodulated, and the Random Access Preamble Identifier (RAPID) in a sub-PDU of the MAC PDU matches the two-step non-contention-based random access preamble sent by the terminal device, then the random access response has been successfully received.

[0426] The subprotocol data unit (subPDU) contains at least a timing advance command (TAC).

[0427] 37. The method as described in Appendix 36, wherein,

[0428] The subPDU also contains uplink authorization information.

[0429] The method further includes: retransmitting the uplink shared channel according to the uplink authorization information.

[0430] 38. The method as described in Appendix 36, wherein the method further comprises:

[0431] Receive uplink grant information in the Physical Downlink Control Channel (PDCCH) addressed to the Cell Radio Network Temporary Identifier (C-RNTI), the uplink grant information being used to schedule the Hybrid Automatic Repeat Request (HARQ) process retransmission of the uplink shared channel; and

[0432] The Physical Uplink Shared Channel (PUSCH) is retransmitted based on the uplink grant information.

[0433] 39. The method as described in Appendices 33, 35, and 38, wherein the method further comprises:

[0434] If a second message (msgB) is not received when an uplink grant information for scheduling retransmission of the Physical Uplink Shared Channel (PUSCH) is received, the Physical Uplink Shared Channel (PUSCH) will not be retransmitted according to the uplink grant information.

[0435] 40. The method as described in Appendix 31, wherein receiving the second message (MsgB) sent by the network device and the response to the Hybrid Automatic Repeat Request (HARQ) sent for the Physical Uplink Shared Channel determines that random access is complete.

[0436] The response to the Hybrid Automatic Repeat Request (HARQ) is used to indicate that the network device has successfully demodulated the physical uplink shared channel.

[0437] 41. The method as described in Appendix 40, wherein,

[0438] The response to the Hybrid Automatic Repeat Request (HARQ) is a correct response to the HARQ carried by the physical downlink control channel; or

[0439] The response to the Hybrid Automatic Repeat Request (HARQ) is new data from the HARQ process scheduled by the physical downlink control channel.

[0440] 42. A random access method, applied to a network device, comprising:

[0441] Send two-step non-contention-based random access resource configuration to the terminal device; and

[0442] The terminal device receives the first message (MsgA) of the two-step non-contention random access procedure, which includes the two-step non-contention random access preamble and the physical uplink shared channel.

[0443] 43. The method as described in Appendix 42, wherein,

[0444] Two-step non-contention random access resource configuration is sent to the terminal device via Physical Downlink Control Channel (PDCCH) or Radio Resource Control (RRC) signaling.

[0445] 44. The method as described in Appendix 42, wherein,

[0446] The two-step non-contention random access resource includes a dedicated two-step random access resource; the dedicated two-step random access resource includes at least one synchronization signal block (SSB) or channel state information reference signal (CSI-RS), and a dedicated two-step random access preamble corresponding to the synchronization signal block (SSB) or channel state information reference signal (CSI-RS).

[0447] 45. The method as described in Appendix 42, wherein the method further comprises:

[0448] Successfully demodulated the two-step non-contention-based random access preamble; and

[0449] Send a second message (MsgB) to the terminal device.

[0450] 46. ​​The method as described in Appendix 45, wherein the step of sending the second message (MsgB) to the terminal device comprises:

[0451] The terminal device is sent a Physical Downlink Control Channel (PDCCH) addressed to a Cell Radio Network Temporary Identifier (C-RNTI) and a Media Access Control Protocol Data Unit (MAC PDU) scheduled by the PDCCH.

[0452] The MACPDU includes a timing advance command media access layer control unit (TAC MAC CE).

[0453] 47. The method as described in Appendix 46, wherein the method further comprises:

[0454] If the two-step non-contention-based random access preamble is demodulated, but the uplink shared channel is not demodulated,

[0455] Sending a Physical Downlink Control Channel (PDCCH) addressed to the Cell Radio Network Temporary Identifier (C-RNTI) to the terminal device, the PDCCH containing uplink grant information used to schedule HARQ process retransmission of the uplink shared channel; and

[0456] The terminal device receives the HARQ process retransmission of the uplink shared channel based on the uplink authorization information.

[0457] 48. The method as described in Appendix 47, wherein,

[0458] Before sending the Physical Downlink Control Channel (PDCCH) addressed to the Cell Radio Network Temporary Identifier (C-RNTI) to the terminal device, the second message (MsgB) is sent.

[0459] The PDCCH contains uplink scheduling information for scheduling HARQ process retransmissions of the uplink shared channel.

[0460] 49. The method as described in Appendix 46, wherein the step of sending the second message (MsgB) to the terminal device further comprises:

[0461] If the two-step non-contention-based random access preamble is successfully demodulated, but the uplink shared channel is not successfully demodulated,

[0462] Send a Physical Downlink Control Channel (PDCCH) addressed to the terminal device, and send a MAC PDU scheduled by the PDCCH.

[0463] The RAPID in a sub-protocol data unit (subPDU) included in the MAC PDU matches the two-step non-contention random access preamble, and the subPDU contains at least uplink grant information.

[0464] 50. The method as described in Appendix 49, wherein,

[0465] The uplink authorization information contained in the subPDU is used by the terminal device to retransmit the uplink shared channel;

[0466] The method further includes:

[0467] The uplink shared channel retransmitted by the terminal device is received based on the uplink grant information in the subPDU.

[0468] 51. The method as described in Appendix 45, wherein the step of sending the second message (MsgB) to the terminal device comprises:

[0469] Send a Physical Downlink Control Channel (PDCCH) addressed to the terminal device, and send a MAC PDU scheduled by the PDCCH.

[0470] The RAPID in a sub-protocol data unit (subPDU) included in the MAC PDU matches the two-step non-contention random access preamble, and the subPDU contains at least a timing advance command (TAC).

[0471] 52. The method as described in Appendix 51, wherein,

[0472] The subPDU also includes uplink authorization information, which is used by the terminal device to retransmit the uplink shared channel.

[0473] The method further includes:

[0474] The uplink shared channel retransmitted by the terminal device is received according to the uplink authorization information.

[0475] 53. The method as described in Appendix 51, wherein the method further comprises:

[0476] Sending a Physical Downlink Control Channel (PDCCH) addressed to the Cell Radio Network Temporary Identifier (C-RNTI) to the terminal device, the PDCCH containing uplink grant information used to schedule HARQ process retransmission of the uplink shared channel; and

[0477] The terminal device receives the HARQ process retransmission of the uplink shared channel based on the uplink authorization information.

[0478] 54. The method as described in Appendix 53, wherein,

[0479] Before sending the Physical Downlink Control Channel (PDCCH) addressed to the Cell Radio Network Temporary Identifier (C-RNTI) to the terminal device, the second message (MsgB) is sent;

[0480] The PDCCH contains uplink scheduling information for scheduling HARQ process retransmissions of the uplink shared channel.

[0481] 55. The method as described in Appendix 45, wherein the method further comprises:

[0482] In the case of demodulating the aforementioned uplink shared channel

[0483] Send a response to the Hybrid Automatic Repeat Request (HARQ) sent to the terminal device for the uplink shared channel.

[0484] The response to the Hybrid Automatic Repeat Request (HARQ) is used to indicate that the network device has successfully demodulated the uplink shared channel.

[0485] 56. The method as described in Appendix 55, wherein,

[0486] The response to the Hybrid Automatic Repeat Request (HARQ) is a correct response to the HARQ carried by the physical downlink control channel; or

[0487] The response to the Hybrid Automatic Repeat Request (HARQ) is new data from the HARQ process scheduled by the physical downlink control channel.

[0488] 57. The method as described in Appendix 42, wherein the method further comprises:

[0489] Upon successful demodulation of the two-step non-contention random access preamble and successful demodulation of the uplink shared channel, a second message (MsgB) is sent to the terminal device.

Claims

1. A random access apparatus applied to a terminal device, the apparatus comprising a first processing unit, the first processing unit being configured to: determine a random access type according to configuration information of a bandwidth part (BWP) selected by the terminal device for random access and a downlink reference signal received power measured by the terminal device; select a random access resource; and transmit an initial message of random access on the random access resource, wherein the step of selecting the random access resource comprises: selecting a two-step random access resource after determining that the random access type is two-step random access; and selecting a four-step random access resource after determining that the random access type is four-step random access, wherein the step of selecting the two-step random access resource comprises: selecting a two-step contention-free random access resource if a selection condition of the two-step contention-free random access resource is met; and selecting a two-step contention-based random access resource if the selection condition of the two-step contention-free random access resource is not met, wherein the step of selecting the two-step contention-free random access resource comprises: selecting a synchronization signal block (SSB) whose reference signal received power (RSRP) is higher than a second threshold value for selecting an SSB received from a network device; setting a two-step random access preamble to be transmitted as a dedicated two-step random access preamble corresponding to the SSB; determining a preamble access opportunity of two-step random access corresponding to a next available SSB; and determining an uplink grant according to a physical uplink shared channel (PUSCH) corresponding to the two-step random access preamble and the preamble access opportunity, wherein setting the two-step random access preamble to be transmitted as the dedicated two-step random access preamble comprises setting the two-step random access preamble to be transmitted as a dedicated two-step random access preamble of a group A or a group B corresponding to the SSB according to a transport block size (TB size) of a first message (MsgA) of a two-step contention-free random access procedure, wherein the dedicated two-step random access preambles of the group A and the group B correspond to the PUSCH. determining the random access type according to the configuration information of the bandwidth part selected by the terminal device and the downlink reference signal received power measured by the terminal device comprises: determining the random access type as two-step random access if the bandwidth part (BWP) selected by the terminal device is configured with two-step random access resources and the downlink reference signal received power measured by the terminal device is higher than a first threshold value, or determining the random access type as two-step random access if the bandwidth part (BWP) selected by the terminal device is configured only with two-step random access resources; otherwise, determining the random access type as four-step random access. the selection condition of the two-step contention-free random access resource is met comprises: the bandwidth part (BWP) selected by the terminal device is configured with two-step random access resources; and the downlink reference signal received power measured by the terminal device is higher than the first threshold value. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2. The apparatus of claim 1, wherein, ​ ​ 3. The apparatus of claim 1, wherein, ​ The terminal device is configured by a network device with a dedicated two-step random access resource, and a reference signal receiving power (RSRP) of at least one synchronization signal block (SSB) in the dedicated two-step random access resource is higher than a second threshold value; The dedicated two-step random access resource includes at least one synchronization signal block (SSB) and a dedicated two-step random access preamble corresponding to the synchronization signal block (SSB).

4. The apparatus of claim 1, wherein, The modulation and coding strategy (MCS) of the physical uplink shared channel (PUSCH) corresponding to the dedicated two-step random access preambles of the group A and the group B are different.

5. The apparatus of claim 1, wherein, If the two-step random access resource is selected, or if the random access type is two-step random access: If the random access procedure is not successfully completed, the two-step random access resource selection is re-performed.

6. The apparatus of claim 5, wherein, If the random access procedure is not successfully completed, and the count value of the random access preamble sent is greater than a threshold value N: The random access type is set to four-step random access, and four-step random access resource selection is performed.

7. The apparatus of claim 5, wherein, The step of re-performing random access resource selection includes: If it is determined that there is a two-step contention-free random access resource that meets the selection condition within a backoff time, or there is a contention-free random access resource that meets the selection condition, the random access resource selection is re-performed before the end of the backoff time; otherwise, the random access resource selection is re-performed after the end of the backoff time.

8. A random access apparatus applied to a terminal device, the apparatus comprising a third processing unit, the third processing unit: Receives a two-step contention-free random access resource configuration for a first message (MsgA) sent by a network device; Sends the first message (MsgA) of a two-step contention-free random access procedure to the network device, the first message including a two-step contention-free random access preamble and a physical uplink shared channel; When receiving a second message (MsgB) sent by the network device, it is determined that the random access response reception is successful and the random access is considered to be successfully completed; and Sends the physical uplink shared channel transmission included in the first message (MsgA) to the network device, wherein The reception of the second message (MsgB) sent by the network device includes: Successfully demodulates a physical downlink control channel scheduling media access control layer protocol data unit (MAC PDU) addressed to a second message radio network temporary identifier (MsgB-RNTI), and a random access preamble identifier (RAPID) in a sub-protocol data unit (subPDU) in the media access control layer protocol data unit (MAC PDU) matches the two-step contention-free random access preamble sent by the terminal device, The subPDU includes at least a timing advance command (TAC) and uplink grant (UL Grant) information for the physical uplink shared channel transmission included in the first message (MsgA). 9.The apparatus of claim 8, wherein, The third processing unit receives the two-step contention-based random access resource configuration through physical downlink control channel (PDCCH) or radio resource control (RRC) signaling. 10.The apparatus of claim 8, wherein, The two-step contention-based random access resource includes a dedicated two-step random access resource, The dedicated two-step random access resource includes at least one synchronization signal block (SSB) or channel state information reference signal (CSI-RS) and a dedicated two-step random access preamble corresponding to the synchronization signal block (SSB) or channel state information reference signal (CSI-RS).

11. The apparatus of claim 8, wherein, The third processing unit further: opens a reception window for a second message (MsgB) and listens to a physical downlink control channel (PDCCH) addressed to a cell radio network temporary identifier (C-RNTI) and a physical downlink control channel (PDCCH) addressed to a second message radio network temporary identifier (MsgB-RNTI) when the reception window for the second message (MsgB) is running. 12.The apparatus of claim 8, wherein, The third processing unit further retransmits the uplink shared channel according to the uplink grant information of the first message (MsgA). 13.A random access apparatus applied to a terminal device, the apparatus comprising a third processing unit, the third processing unit: receives a two-step contention-based random access resource configuration for a first message (MsgA) sent by a network device; sends the first message (MsgA) of a two-step contention-based random access process to the network device, the first message including a two-step contention-based random access preamble and a physical uplink shared channel; receiving uplink grant information in a physical downlink control channel (PDCCH) addressed to a cell radio network temporary identifier (C-RNTI), the uplink grant information being used for scheduling a hybrid automatic repeat request (HARQ) process retransmission of the uplink shared channel and performing the hybrid automatic repeat request (HARQ) process retransmission of the uplink shared channel according to the uplink grant information; and determines that a random access response reception is successful and considers that a random access is successfully completed when a second message (MsgB) sent by the network device is received, wherein, the second message (MsgB) sent by the network device is received, including: successfully demodulating a medium access control layer protocol data unit (MAC PDU) scheduled by a physical downlink control channel (PDCCH) addressed to a cell radio network temporary identifier (C-RNTI), and the medium access control layer protocol data unit including a timing advance command medium access layer control unit (TAC MAC CE), wherein the step of sending the first message (MsgA) of a two-step contention-based random access process to the network device includes: selecting a synchronization signal block (SSB) whose reference signal received power (RSRP) for sending a dedicated two-step random access preamble and a physical uplink shared channel (PUSCH) is higher than a second threshold value for selecting a synchronization signal block (SSB) received from the network device; setting a two-step random access preamble to be sent as a dedicated two-step random access preamble corresponding to the synchronization signal block (SSB); determining a preamble access opportunity of two-step random access corresponding to a next available synchronization signal block (SSB); determining an uplink grant according to a physical uplink shared channel (PUSCH) corresponding to the two-step random access preamble and the preamble access opportunity; and sending the first message (MsgA) according to the uplink grant.

14. The apparatus of claim 13, wherein, The third processing unit further: if no second message (msgB) is received when receiving uplink grant information for scheduling retransmission of a physical uplink shared channel (PUSCH), not retransmitting the physical uplink shared channel (PUSCH) according to the uplink grant information.

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