Random access method and communication apparatus

Abstract

The application provides a random access method and a communication device, which can make a terminal device clear about what type of random access is performed. The method comprises the following steps: determining at least one random access preamble from at least one two-step random access preamble, or determining one random access preamble from at least one two-step random access preamble and at least one four-step random access preamble; and performing random access by using the determined random access preamble.

Description

[0001] This application is a divisional application of the original application filed with the China National Intellectual Property Administration on April 26, 2019, with application number "201910346571.3", wherein the original application is incorporated herein by reference. Technical Field

[0002] This application relates to the field of communications, and more specifically, to a method and apparatus for random access. Background Technology

[0003] In wireless communication technology, terminal devices obtain uplink synchronization with network devices through a random access procedure. Currently, random access types include four-step random access and two-step random access. Network devices can simultaneously configure random access channel (RACH) resources for four-step random access and RACH resources for two-step random access. In this scenario, the terminal device cannot determine which type of random access is required. Summary of the Invention

[0004] This application provides a random access method and communication device that enables terminal devices to specify the type of random access to be performed.

[0005] In one aspect, a random access method is provided, comprising: determining a random access preamble; and using the random access preamble to perform random access.

[0006] The random access preamble is at least one determined from at least one two-step random access preamble, or it is one determined from at least one two-step random access preamble and at least one four-step random access preamble. The at least one two-step random access preamble is a random access preamble configured by the network device for two-step random access. The at least one four-step random access preamble is a random access preamble configured by the network device for four-step random access.

[0007] According to the method provided in this application, in a scenario where the network device is configured with both a random access preamble for four-step random access and a random access preamble for two-step random access, the terminal device can choose to use the two-step random access preamble for two-step random access, or the terminal device can randomly select one of the configured two-step random access preambles and four-step random access preambles to perform the corresponding type of random access.

[0008] Optionally, the random access may be used for initial data transmission or for data retransmission.

[0009] In other words, the random access preamble is used for random access during the initial data transmission; or, the random access preamble is used for random access during data retransmission.

[0010] In conjunction with the first aspect, in some implementations of the first aspect, when the random access is for the initial data transmission, the method may further include: performing a two-step random access if the random access fails.

[0011] Since two-step random access takes less time than four-step random access, using two-step random access can reduce access latency.

[0012] In conjunction with the first aspect, in some implementations of the first aspect, when the random access is for data retransmission, the method may further include: performing two-step random access or four-step random access in the event of random access failure.

[0013] Based on this scheme, in the event that random access for data retransmission fails, the terminal device can flexibly select the random access type.

[0014] In conjunction with the first aspect, in some implementations of the first aspect, in the event of a failure of random access, the method may further include: receiving indication information sent by a network device, the indication information being used to instruct the terminal device to perform two-step random access, or the indication information being used to instruct the terminal device to perform four-step random access; and performing random access according to the indication information.

[0015] Based on this scheme, terminal devices can determine the type of random access according to the instructions of network devices.

[0016] In conjunction with the first aspect, in certain implementations of the first aspect, the random access preamble is a two-step random access preamble, the at least one two-step random access preamble corresponds to at least one first data volume threshold, the first data volume threshold corresponding to a two-step random access preamble is the maximum data volume supported by the two-step random access preamble, and each first data volume threshold corresponds to a second signal strength threshold. Furthermore, determining the random access preamble includes:

[0017] If there is a reference signal with a reference signal receiving power (RSRP) greater than a first signal strength threshold among at least one reference signal configured in the network device, a target reference signal is selected from the reference signals with a reference signal receiving power (RSRP) greater than the first signal strength threshold. The reference signal is either a synchronization signal block (SSB) or a channel state information reference signal resource (CSI-RS).

[0018] If the amount of data to be transmitted is less than or equal to one of the at least one first data amount thresholds, and the RSRP of the target reference signal is greater than the target second signal strength threshold, the random access preamble is determined from the two-step random access preamble corresponding to the target reference signal. The first data amount threshold corresponding to the random access preamble is the first data amount threshold corresponding to the target second signal strength threshold. Wherein, the target second signal strength threshold is the second signal strength threshold corresponding to the first data amount threshold corresponding to the amount of data to be transmitted. Alternatively, the random access preamble supports the amount of data to be transmitted.

[0019] Based on this scheme, a target reference signal can be selected first using existing technology, and then the random access preamble can be determined based on the relationship between the amount of data to be transmitted and the first data amount threshold, as well as the relationship between the RSRP corresponding to the target reference signal and the second signal strength threshold.

[0020] As an alternative to this scheme, instead of selecting a target reference signal, the random access preamble can be determined directly based on the random access preamble corresponding to the reference signal whose RSRP is greater than the target second signal strength threshold. For example, a random access preamble supporting the amount of data to be transmitted can be directly selected from the random access preambles corresponding to reference signals whose RSRP is greater than the target second signal strength threshold. Since the random access preambles corresponding to some reference signals may not include two-step random access preambles, this scheme increases the probability of selecting two-step random access preambles compared to the aforementioned scheme of first selecting the target reference signal and then determining the random access preamble.

[0021] It should be understood that there is a correspondence between random access preambles and physical uplink shared channel (PUSCH) resources. One PUSCH resource corresponds to the maximum transmit block size (TBS). We can consider the random access preamble to correspond to the TBS, and this means that when the amount of data to be transmitted is less than (or less than or equal to) the TBS, the random access preamble corresponding to that TBS can be used. Therefore, the amount of data supported by a random access preamble refers to the TBS of the PUSCH resource corresponding to that random access preamble.

[0022] In conjunction with the first aspect, in certain implementations of the first aspect, the random access preamble is a two-step random access preamble, and the at least one two-step random access preamble corresponds to at least one first data volume threshold. The first data volume threshold corresponding to a two-step random access preamble is the maximum data volume that the two-step random access preamble supports for transmission. Each first data volume threshold corresponds to a PL1, and PL1 is a first path loss threshold. Furthermore, determining the random access preamble includes:

[0023] If there is a reference signal with a corresponding reference signal received power RSRP greater than a first signal strength threshold among at least one reference signal configured in the network device, a target reference signal is selected from the reference signals greater than the first signal strength threshold. The reference signal is either a synchronization signal block SSB or a channel state information reference signal CSI-RS.

[0024] If the amount of data to be transmitted is less than or equal to one of the at least one first data amount thresholds, and the path loss corresponding to the target reference signal is less than the target PL1, the random access preamble is determined from the two-step random access preamble corresponding to the target reference signal.

[0025] Wherein, the target PL is the second signal strength threshold corresponding to the first data volume threshold corresponding to the amount of data to be transmitted, or, the first data volume threshold corresponding to the random access preamble is the first data volume threshold corresponding to the target second signal strength threshold; or, the amount of data to be transmitted supported by the random access preamble. PL1 = PCMAX - TP - Δ1, where PL1 is the first path loss threshold, PCMAX is the maximum transmit power of the terminal equipment in the cell performing random access, TP is the target receive power of the two-step random access preamble, Δ1 is the power deviation between the data to be transmitted and the two-step random access preamble, and the target PL1 is the PL1 corresponding to the first data volume threshold corresponding to the amount of data to be transmitted.

[0026] Based on this scheme, a target reference signal can be selected first using existing technology, and then the random access preamble can be determined based on the relationship between the amount of data to be transmitted and the first data amount threshold, as well as the relationship between the path loss and PL1 corresponding to the target reference signal.

[0027] As an alternative to this scheme, instead of selecting a target reference signal, the random access preamble can be determined directly based on the random access preamble corresponding to the reference signal whose path loss is less than the target PL1 among the at least one reference signal. For example, a random access preamble supporting the amount of data to be transmitted can be directly selected from the random access preambles corresponding to the reference signals whose path loss is less than the target PL1. Since the random access preambles corresponding to some reference signals may not include two-step random access preambles, this scheme can increase the probability of selecting a two-step random access preamble.

[0028] In conjunction with the first aspect, in some implementations of the first aspect, the random access preamble is a two-step random access preamble. Furthermore, determining the random access preamble includes:

[0029] If there is a reference signal with a corresponding reference signal received power RSRP greater than a first signal strength threshold among at least one reference signal configured in the network device, a target reference signal is selected from the reference signals with corresponding RSRP greater than the first signal strength threshold. The reference signal is either a synchronization signal block SSB or a channel state information reference signal CSI-RS.

[0030] Determine whether a first set of random access preambles has been configured, and whether the amount of data that can be sent supported by the first set of random access preambles is greater than the second data amount threshold;

[0031] If the first set of random access preambles is configured, and the amount of data to be transmitted is greater than the second data amount threshold, and the path loss corresponding to the target reference signal is less than PL2, then the random access preamble is determined from the random access preambles belonging to the first set of random access preambles corresponding to the target reference signal; or,

[0032] If the first set of random access preambles is configured, and the amount of data to be transmitted is less than or equal to the second data amount threshold, the random access preamble is determined from the random access preambles belonging to the second set of random access preambles corresponding to the target reference signal, and the maximum amount of data that the second set of random access preambles supports is the second data amount threshold; or,

[0033] If the first set of random access preambles is configured, and the path loss corresponding to the target reference signal is greater than or equal to PL2, the random access preamble is determined from the random access preambles belonging to the second set of random access preambles corresponding to the target reference signal.

[0034] Wherein, PL2 = PCMAX - TP - Δ1 - Δ2, PL2 is the second path loss threshold, PCMAX is the maximum transmit power of the terminal equipment in the cell where random access is performed, TP is the target receive power of the random access preamble for two-step random access, Δ1 is the power deviation between the data to be transmitted and the two-step random access preamble, and Δ2 is the power deviation between the first set of random access preambles and the second set of random access preambles.

[0035] Based on this scheme, a random access preamble can be selected from the first group of random access preambles for random access, or a random access preamble can be selected from the second group of random access preambles for random access.

[0036] It should be understood that the first set of random access preambles and the second set of random access preambles constitute a two-step random access preamble. The at least one random access preamble includes both the first set of random access preambles and the second set of random access preambles.

[0037] In conjunction with the first aspect, in some implementations of the first aspect, the random access preamble is a two-step random access preamble. Furthermore, determining the random access preamble includes:

[0038] If there is a reference signal with a corresponding reference signal received power RSRP greater than a first signal strength threshold among at least one reference signal configured in the network device, a target reference signal is selected from the reference signals with corresponding RSRP greater than the first signal strength threshold. The reference signal is either a synchronization signal block SSB or a channel state information reference signal CSI-RS.

[0039] Determine whether a first set of random access preambles has been configured, and whether the amount of data that can be sent supported by the first set of random access preambles is greater than the second data amount threshold;

[0040] If the first set of random access preambles is configured, and the amount of data to be transmitted is greater than the second data amount threshold, and the data to be transmitted is carried through the common control channel (CCCH), the random access preamble is determined from the random access preambles belonging to the first set of random access preambles corresponding to the target reference signal, and the maximum amount of data that the second set of random access preambles supports for transmission is the second data amount threshold; or,

[0041] If the first set of random access preambles is configured, and the amount of data to be transmitted is less than or equal to the second data amount threshold, the random access preamble is determined from the random access preambles belonging to the second set of random access preambles corresponding to the target reference signal; or,

[0042] If the first set of random access preambles is configured, and the data to be transmitted is not carried by the CCCH, the random access preamble is determined from the random access preambles belonging to the second set of random access preambles corresponding to the target reference signal.

[0043] Based on this scheme, a random access preamble can be selected from the first group of random access preambles for random access, or a random access preamble can be selected from the second group of random access preambles for random access.

[0044] In conjunction with the first aspect, in some implementations of the first aspect, the random access preamble is a two-step random access preamble; and, determining the random access preamble includes:

[0045] If the first set of random access preambles is not configured, the random access preamble is determined from the random access preambles belonging to the second set of random access preambles corresponding to the target reference signal.

[0046] In conjunction with the first aspect, in certain implementations of the first aspect, the random access preamble is a two-step random access preamble, the at least one two-step random access preamble corresponds to at least one first data volume threshold, the first data volume threshold corresponding to a two-step random access preamble is the maximum data volume supported by the two-step random access preamble, and each first data volume threshold corresponds to a second signal strength threshold. Furthermore, determining the random access preamble includes:

[0047] If the amount of data to be transmitted is less than or equal to one of the at least one first data amount thresholds, and there is a reference signal among the at least one reference signal configured by the network device whose corresponding reference signal received power RSRP is greater than the target second signal strength threshold, a target reference signal is selected from the reference signals whose corresponding RSRP is greater than the second signal strength threshold. The reference signal is a synchronization signal block SSB or a channel state information reference signal CSI-RS. The target second signal strength is the second signal strength threshold corresponding to the first data amount threshold corresponding to the amount of data to be transmitted.

[0048] The random access preamble is determined from the two-step random access preamble corresponding to the target reference signal.

[0049] Wherein, the target second signal strength threshold is the second signal strength threshold corresponding to the first data volume threshold corresponding to the data volume to be transmitted, or in other words, the first data volume threshold corresponding to the random access preamble is the first data volume threshold corresponding to the target second signal strength threshold; or, the random access preamble supports the data volume to be transmitted.

[0050] Based on this scheme, the random access preamble can be determined according to the relationship between the amount of data to be transmitted and a first data amount threshold, and the relationship between the RSRP of the target reference signal and a second signal strength threshold. Compared with the scheme that first selects a reference signal based on a first signal strength threshold and then determines the relationship between the reference signal and the second signal strength threshold to select a random access preamble, this scheme is simpler to implement.

[0051] In conjunction with the first aspect, in some implementations of the first aspect, the random access preamble is a two-step random access preamble, the at least one two-step random access preamble corresponds to at least one first data volume threshold, the first data volume threshold corresponding to a two-step random access preamble is the maximum amount of data that the two-step random access preamble supports, and each first data volume threshold corresponds to a second signal strength threshold.

[0052] And, the determination of the random access preamble includes:

[0053] If the amount of data to be transmitted is less than or equal to one of the at least one first data amount thresholds, and there is a reference signal with a corresponding Reference Signal Received Power (RSRP) greater than a target second signal strength threshold among the at least one reference signal configured in the network device, the random access preamble is selected from the random access preambles corresponding to the reference signals greater than the second signal strength threshold. The reference signal is a Synchronization Signal Block (SSB) or a Channel State Information Reference Signal (CSI-RS), and the target second signal strength is the second signal strength threshold corresponding to the first data amount threshold corresponding to the amount of data to be transmitted. The target second signal strength threshold is the second signal strength threshold corresponding to the first data amount threshold corresponding to the amount of data to be transmitted; or, the first data amount threshold corresponding to the random access preamble is the first data amount threshold corresponding to the target second signal strength threshold; or, the random access preamble supports the amount of data to be transmitted.

[0054] Since the random access preamble corresponding to some reference signals may not include two-step random access preamble, this scheme can increase the probability of selecting two-step random access preamble compared to the aforementioned scheme of first selecting the target reference signal and then determining the random access preamble.

[0055] In conjunction with the first aspect, in some implementations of the first aspect, the step of using the random access preamble for random access includes: determining the next available transmission opportunity from the transmission opportunities corresponding to the target reference signal, the transmission opportunity being used to transmit the random access preamble; and using the random access preamble for random access on the available transmission opportunity.

[0056] Secondly, a random access method is provided, the method comprising: generating configuration information; sending the configuration information to a terminal device, the configuration information including at least one first data volume threshold and at least one second signal strength threshold, the at least one first data volume threshold corresponding to at least one two-step random access preamble, the first data volume threshold corresponding to a two-step random access preamble being the maximum data volume supported by the two-step random access preamble, each first data volume threshold corresponding to a second signal strength threshold, the configuration information being used by the terminal device to determine a random access preamble for random access.

[0057] Thirdly, a communication apparatus is provided, including a processing unit and a transceiver unit. The processing unit and the transceiver unit can be used to perform corresponding steps of the methods in the first aspect and any possible implementation thereof.

[0058] Fourthly, a communication device is provided, including a processor. The processor is coupled to a memory and can be used to execute instructions in the memory to implement the methods described in the first aspect and any possible implementation thereof. Optionally, the communication device further includes a memory. Optionally, the communication device further includes a communication interface, to which the processor is coupled.

[0059] In one implementation, the communication device is a terminal device. When the communication device is a terminal device, the communication interface can be a transceiver, or an input / output interface.

[0060] In another implementation, the communication device is a chip configured in the terminal device. When the communication device is a chip configured in the terminal device, the communication interface can be an input / output interface.

[0061] Optionally, the transceiver can be a transceiver circuit. Optionally, the input / output interface can be an input / output circuit.

[0062] Fifthly, a communication apparatus is provided, including a processing unit and a transceiver unit. The processing unit and the transceiver unit can be used to perform corresponding steps in the methods of the second aspect and any possible implementation thereof.

[0063] A sixth aspect provides a communication device including a processor. The processor is coupled to a memory and can be used to execute instructions in the memory to implement the methods of the second aspect and any possible implementation thereof. Optionally, the communication device further includes a memory. Optionally, the communication device further includes a communication interface, to which the processor is coupled.

[0064] In one implementation, the communication device is a network device. When the communication device is a network device, the communication interface can be a transceiver, or an input / output interface.

[0065] In another implementation, the communication device is a chip configured in a network device. When the communication device is a chip configured in a network device, the communication interface can be an input / output interface.

[0066] Optionally, the transceiver can be a transceiver circuit. Optionally, the input / output interface can be an input / output circuit.

[0067] A seventh aspect provides a processor, including: an input circuit, an output circuit, and a processing circuit. The processing circuit is configured to receive signals through the input circuit and transmit signals through the output circuit, causing the processor to execute the methods of the first aspect to the second aspect and any possible implementation thereof.

[0068] In specific implementation, the processor can be a chip, the input circuit can be an input pin, the output circuit can be an output pin, and the processing circuit can be a transistor, gate circuit, flip-flop, and various logic circuits. The input signal received by the input circuit can be received and input by, for example, but not limited to, a receiver, and the signal output by the output circuit can be output to, for example, but not limited to, a transmitter and transmitted by the transmitter. Furthermore, the input circuit and the output circuit can be the same circuit, which is used as the input circuit and the output circuit at different times. This application does not limit the specific implementation of the processor and various circuits.

[0069] Eighthly, a processing apparatus is provided, including a processor and a memory. The processor is configured to read instructions stored in the memory and to receive signals via a receiver and transmit signals via a transmitter to execute the methods of the first aspect to the second aspect and any possible implementation thereof.

[0070] Optionally, the processor may be one or more, and the memory may be one or more.

[0071] Alternatively, the memory can be integrated with the processor, or the memory can be set separately from the processor.

[0072] In specific implementation, the memory can be a non-transitory memory, such as read-only memory (ROM), which can be integrated with the processor on the same chip or set on different chips. The embodiments of this application do not limit the type of memory or the way the memory and processor are set.

[0073] It should be understood that the relevant data interaction process, such as sending measurement configuration information, can be the process of outputting measurement configuration information from the processor, and receiving information can be the process of the processor receiving information. Specifically, the processed output data can be output to the transmitter, and the input data received by the processor can come from the receiver. Here, the transmitter and receiver can be collectively referred to as a transceiver.

[0074] The processing device in the eighth aspect above can be a chip. The processor can be implemented in hardware or software. When implemented in hardware, the processor can be a logic circuit, integrated circuit, etc. When implemented in software, the processor can be a general-purpose processor that reads software code stored in memory. The memory can be integrated into the processor or located outside the processor and exist independently.

[0075] Ninthly, a computer program product is provided, comprising: a computer program (also referred to as code or instructions) that, when run, causes a computer to perform the methods described in the first to second aspects and any possible implementation thereof.

[0076] In a tenth aspect, a computer-readable medium is provided that stores a computer program (also referred to as code or instructions) that, when run on a computer, causes the computer to perform the methods described in the first to second aspects and any possible implementation thereof.

[0077] Eleventhly, a communication system is provided, including the aforementioned network equipment and terminal equipment. Attached Figure Description

[0078] Figure 1 This is a schematic diagram of a communication system applicable to this application;

[0079] Figure 2 This is a schematic diagram of a four-step random access process;

[0080] Figure 3 This is a schematic diagram of a two-step random access process.

[0081] Figure 4This is a schematic flowchart of the random access method provided in this application;

[0082] Figure 5 This application provides a schematic structural diagram of a communication device;

[0083] Figure 6 This is a schematic diagram of the structure of a terminal device provided in this application;

[0084] Figure 7 This is a schematic diagram of the structure of a network device provided in this application. Detailed Implementation

[0085] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0086] The technical solutions of this application can be applied to various communication systems, such as: LTE time division duplex (TDD), universal mobile telecommunication system (UMTS), worldwide interoperability for microwave access (WiMAX) communication system, future 5th generation (5G) system or new radio (NR), etc.

[0087] The terminal device in this application embodiment can refer to user equipment, access terminal, user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent, or user device. The terminal device can also be a cellular phone, cordless phone, session initiation protocol (SIP) phone, wireless local loop (WLL) station, personal digital assistant (PDA), handheld device with wireless communication capabilities, computing device or other processing device connected to a wireless modem, vehicle-mounted device, wearable device, terminal device in future 5G networks, or terminal device in future evolved public land mobile networks (PLMNs), etc., and this application embodiment does not limit this to these categories.

[0088] The network device in this application embodiment can be any device with wireless transceiver capabilities. This device includes, but is not limited to: a baseband unit (BBU), an access point (AP), wireless relay node, wireless backhaul node, transmission point (TP), or transmission and reception point (TRP) in a wireless fidelity (WIFI) system, and can also be a fifth-generation (5G) system, such as a gNB or transmission point (TRP or TP) in a new radio (NR) interface, one or a group of antenna panels (including multiple antenna panels) of a base station in a 5G system, or a network node constituting a gNB or transmission point, such as a baseband unit (BBU) or a distributed unit (DU).

[0089] In some deployments, a gNB may include a centralized unit (CU) and a distribution unit (DU). A gNB may also include an active antenna unit (AAU). The CU implements some of the gNB's functions, and the DU implements others. For example, the CU handles non-real-time protocols and services, implementing radio resource control (RRC) and packet data convergence protocol (PDCP) layer functions. The DU handles physical layer protocols and real-time services, implementing radio link control (RLC), media access control (MAC), and physical (PHY) layer functions. The AAU implements some physical layer processing functions, radio frequency processing, and active antenna-related functions. Since RRC layer information ultimately becomes PHY layer information, or is derived from PHY layer information, in this architecture, higher-layer signaling, such as RRC layer signaling, can be considered to be sent by the DU, or by the DU+AAU. It is understood that network devices can be devices that include one or more of the following: CU nodes, DU nodes, and AAU nodes. In addition, the CU can be classified as a network device in the radio access network (RAN) or as a network device in the core network (CN), and this application does not limit this.

[0090] See Figure 1 , Figure 1 This is an architecture diagram of a communication system applicable to embodiments of this application. For example... Figure 1 As shown, the wireless communication system may include at least one network device 101, and the network device 101 and one or more terminal devices (e.g., Figure 1 The terminal devices 102 and 103 shown communicate with each other. When the network device sends a signal, the network device is the transmitter and the terminal device is the receiver. Conversely, when the terminal device sends a signal, the terminal device is the transmitter and the network device is the receiver.

[0091] To facilitate understanding of the technical solution of this application, a brief introduction to the relevant technologies involved in this application will be given first.

[0092] After the terminal device selects a suitable cell and completes its camping, it can then perform random access.

[0093] See Figure 2 , Figure 2 This is a schematic diagram of a four-step random access procedure. Figure 2 As shown, the terminal device sends message 1 (msg 1) to the network device. Message 1 is the random access preamble. After detecting the random access preamble, the network device returns a response message, message 2, to the terminal device. Message 2 contains the uplink resources allocated to the terminal device by the network side. After receiving message 2, the terminal device sends message 3 on the uplink resources indicated by message 2. If the network device can correctly decode message 3, it returns message 4 to the terminal device. Message 4 is used to notify the terminal device that the contention was successful. After the above four steps, the random access procedure is successful.

[0094] With the introduction of new wireless terminal types such as machine-type communication (MTC) and narrowband Internet of Things (NB-IoT), the number of terminal devices is increasing exponentially. If all terminal devices use the four-step random access method for random access, it will overload the network equipment. In addition, the latency of four-step random access is also relatively long.

[0095] To address these issues, a two-step random access type was introduced.

[0096] See Figure 3 , Figure 3This diagram illustrates a two-step random access process. In this process, the terminal device carries both a random access preamble and data (i.e., preamble + data) in message A. The data portion is typically a radio resource control (RRC) message. If there are no conflicts between terminal devices, the network device successfully decodes message A and returns message B to the terminal devices. Message B includes both a response to the random access preamble and a response to the data. The response to the random access preamble is also known as the random access response (RAR). The response to the data is typically an RRC message. These two responses can be sent simultaneously or sequentially. The terminal device can decode these two responses independently. Upon receiving message B, the terminal device recognizes successful random access. If there are conflicts between terminal devices, the network device may be unable to successfully decode the data in message A; in this case, the network device does not send message B to the terminal devices. After sending message A, the terminal device waits for a time window; if it does not receive message B, it considers the random access to have failed.

[0097] In some cases, the terminal device sends message A, which includes the random access preamble and data, at the occasion configured for two-step random access. If the network device can only successfully decode the random access preamble but not the data, it only replies with a RAR to the terminal device, without responding to the data. After receiving the RAR, the terminal device falls back to the four-step random access procedure, i.e., it retransmits message 1 or message 3. This process is called two-step random access fallback to four-step random access.

[0098] Currently, network devices can be configured with both a random access preamble for four-step random access and a random access preamble for two-step random access. In this scenario, the terminal device cannot determine which type of random access is required.

[0099] Therefore, this application provides a random access method aimed at enabling terminal devices to clearly define the type of random access to be performed. According to the method provided in this application, in scenarios where the network device is simultaneously configured with a random access preamble for four-step random access and a random access preamble for two-step random access, the terminal device can choose to use the two-step random access preamble for two-step random access, or the terminal device can randomly select one random access preamble from the configured two-step and four-step random access preambles to perform the corresponding type of random access.

[0100] The following, combined with Figure 4This application provides a detailed description of the random access method provided. It should be noted that the method described herein uses a terminal device or a network device as examples of the executing entity. However, operations performed by a terminal device can also be performed by a chip configured in the terminal device, and operations performed by a network device can also be performed by a chip configured in the network device.

[0101] Figure 4 This is a schematic flowchart of the random access method 200 provided in this application. Method 200 mainly includes steps S410 to S420. The steps are described below.

[0102] S410, the terminal device determines the random access preamble.

[0103] S420, the terminal device uses the determined random access preamble to perform random access.

[0104] For the sake of distinction, the random access preamble determined by the terminal device will be referred to as the target random access preamble.

[0105] The target random access preamble is at least one determined from the two-step random access preamble configured by the network device. Alternatively, the target random access preamble is one of the two-step random access preamble and the four-step random access preamble configured by the network device; that is, the target random access preamble is one of the two-step random access preamble and the four-step random access preamble. The number of two-step random access preambles configured by the network device is at least one, and the number of four-step random access preambles configured by the network device is at least one. The two-step random access preamble is used for two-step random access, and the four-step random access preamble is used for four-step random access.

[0106] If the target random access preamble determined by the terminal device is a two-step random access preamble, then the terminal device performs two-step random access. If the target random access preamble determined by the terminal device is a four-step random access preamble, then the terminal device performs four-step random access.

[0107] According to the method provided in this application, in a scenario where the network device is configured with both a random access preamble for four-step random access and a random access preamble for two-step random access, the terminal device can choose to use the two-step random access preamble for two-step random access, or the terminal device can randomly select one of the configured two-step random access preambles and four-step random access preambles to perform the corresponding type of random access.

[0108] Optionally, prior to S410, the method may further include:

[0109] S402, Network devices generate configuration information;

[0110] S404, the network device sends configuration information to the terminal device. Correspondingly, the terminal device receives the configuration information sent by the network device.

[0111] Specifically, network devices can configure a reference signal set using this configuration information or other configuration information. This reference signal set can include an SSB set and a CSI-RS set. Network devices can configure the RACH resources corresponding to each SSB in the SSB set and the RACH resources corresponding to each CSI-RS in the CSI-RS set using this configuration information. Generally, network devices can configure the RACH resources corresponding to any two SSBs or CSI-RSs to be the same or different. Network devices can also configure the random access codes corresponding to any SSB to be different or the same.

[0112] Furthermore, the RACH resources corresponding to each SSB may include two-step RACH resources and four-step RACH resources. Alternatively, some SSBs may have RACH resources that include two-step RACH resources, while others may have RACH resources that include four-step RACH resources. Two-step RACH resources include a two-step random access preamble and a two-step random access transmission timing, the latter used to transmit the two-step random access preamble. Four-step RACH resources include a four-step random access preamble and a four-step random access transmission timing, the latter used to transmit the four-step random access preamble. The transmission timing includes at least one of time-domain resources and frequency-domain resources.

[0113] Optionally, the transmission timing for two-step random access and four-step random access can be shared; that is, the configured transmission timing for two-step random access and four-step random access are the same, but this application does not limit this. In one implementation, if the transmission timing for two-step random access is not explicitly configured, but a two-step random access preamble is configured, then it is considered that the transmission timing for two-step random access is the same as the configured transmission timing for four-step random access.

[0114] In another implementation, if the two-step random access preamble is not explicitly indicated, it is considered to be the same as the four-step random access preamble. For example, if the two-step random access preamble is not explicitly configured, but the timing of the two-step random access transmission is configured, it is considered to be the same as the configured four-step random access preamble.

[0115] Generally, the timing of sending two-step random access and four-step random access protocols configured in a network device can be different or the same. When they are the same, the two-step random access preamble and the four-step random access preamble can be different. However, this application does not exclude the possibility that the timing of sending two-step random access and four-step random access protocols configured in the network device are the same, or that the two-step random access preamble and the four-step random access preamble are the same.

[0116] It should be noted that this article only uses the example of each SSB having a corresponding transmission timing and random access preamble. In reality, some SSBs may not have a corresponding transmission timing, and therefore no corresponding random access preamble.

[0117] The following example, using SSB, illustrates the possible correspondence between reference signals and RACH resources.

[0118] Correspondence 1

[0119] Each SSB corresponds to at least one transmission opportunity. Any two SSBs may correspond to the same transmission opportunity, or any two SSBs may correspond to different transmission opportunities. It should be understood that any two SSBs corresponding to different transmission opportunities mean that there is no overlap between the transmission opportunities corresponding to the two SSBs. Similar expressions below will have a similar meaning and will not be repeated in the following text. When any two SSBs correspond to different transmission opportunities, the number of transmission opportunities corresponding to any two SSBs may be equal or unequal. Each SSB corresponds to at least one two-step random access preamble and at least one four-step random access preamble. The at least one two-step random access preamble and the at least one four-step random access preamble are different, meaning there is no overlap between the at least one two-step random access preamble and the at least one four-step random access preamble. The number of two-step random access preambles and the number of four-step random access preambles corresponding to an SSB may be equal or unequal. Any two SSBs may correspond to the same two-step random access preamble or different two-step random access preambles. The number of two-step random access preambles corresponding to any two SSBs may be equal or unequal. The four-step random access preambles corresponding to any two SSBs can be the same or different. The number of four-step random access preambles corresponding to any two SSBs can be equal or unequal. The two-step random access preamble and the four-step random access preamble corresponding to an SSB can share the transmission timing corresponding to that SSB.

[0120] The following explanation will use the example of a set of SSBs containing a total of 4 SSBs.

[0121] For example, see Table 1, which shows the cases of different SSBs corresponding to different transmission times, different two-step random access preambles, and different four-step random access preambles.

[0122] Table 1

[0123]

[0124] For example, see Table 2, which shows the cases where different SSBs correspond to different transmission times, the same two-step random access preamble, and the same four-step random access preamble. It should be understood that different SSBs can also correspond to the same two-step random access preamble and different four-step random access preambles. Alternatively, different SSBs can correspond to different two-step random access preambles and the same four-step random access preamble.

[0125] Table 2

[0126]

[0127] For example, see Table 3, which shows the cases of different SSBs corresponding to the same transmission timing, different two-step random access preambles, and different four-step random access preambles.

[0128] Table 3

[0129]

[0130]

[0131] For example, see Table 4, which shows the cases of different SSBs corresponding to the same transmission timing, the same two-step random access preamble, and the same four-step random access preamble.

[0132] Table 4

[0133]

[0134] Correspondence 2

[0135] Each SSB corresponds to at least one random access preamble. This preamble can be used for both two-step and four-step random access, meaning that the at least one random access preamble corresponding to an SSB is shared by both two-step and four-step random access methods. Any two SSBs can have the same or different random access preambles. Furthermore, the number of random access preambles corresponding to any two SSBs can be the same or different under different circumstances.

[0136] Each SSB corresponds to at least one two-step random access transmission opportunity and at least one four-step random access transmission opportunity. The at least one two-step random access transmission opportunity and the at least one four-step random access transmission opportunity are different. The number of two-step random access transmission opportunities and four-step random access transmission opportunities corresponding to an SSB can be equal or unequal. The two-step random access transmission opportunities corresponding to any two SSBs can be the same or different. The number of two-step random access transmission opportunities corresponding to any two SSBs can be equal or unequal. The four-step random access transmission opportunities corresponding to any two SSBs can be the same or different. The number of four-step random access transmission opportunities corresponding to any two SSBs can be equal or unequal. The two-step random access transmission opportunities and four-step random access transmission opportunities corresponding to an SSB can share the random access preamble corresponding to that SSB.

[0137] For example, see Table 4, which shows the cases where the transmission timing of two-step random access and four-step random access correspond to the same random access preamble.

[0138] Table 4

[0139]

[0140]

[0141] For example, see Table 5, which shows another case where the transmission timing of two-step random access and four-step random access correspond to the same random access preamble.

[0142] Table 5

[0143]

[0144] For example, see Table 6, which shows the transmission timing of two-step random access and four-step random access for different random access preambles.

[0145] Table 6

[0146]

[0147] Correspondence 3

[0148] In this set of SSBs, some SSBs correspond to two-step random access preambles, while others correspond to four-step random access preambles. The number of SSBs corresponding to two-step random access preambles and the number of SSBs corresponding to four-step random access preambles can be equal or unequal.

[0149] Under correspondence three, optionally, each SSB corresponds to at least one transmission opportunity, and any two SSBs correspond to the same transmission opportunity. Furthermore, different SSBs correspond to different random access preambles. The number of random access preambles corresponding to any two SSBs can be equal or unequal.

[0150] For example, see Table 7, which shows the cases where different SSBs correspond to the same transmission timing and different random access preambles.

[0151] Table 7

[0152]

[0153] Under correspondence three, optionally, each SSB corresponds to at least one transmission opportunity, and any two SSBs correspond to different transmission opportunities. The number of transmission opportunities for any two SSBs can be equal or unequal. Furthermore, different SSBs correspond to different random access preambles. The number of random access preambles for any two SSBs can be equal or unequal.

[0154] For example, see Table 8, which shows the cases of different SSBs corresponding to different transmission times and different random access preambles.

[0155] Table 8

[0156]

[0157]

[0158] Under correspondence three, optionally, each SSB corresponds to at least one transmission opportunity, and any two SSBs correspond to different transmission opportunities. The number of transmission opportunities corresponding to any two SSBs can be equal or unequal. Furthermore, different SSBs correspond to the same random access preamble, meaning that the same random access preamble has different functions when corresponding to different SSBs.

[0159] For example, see Table 9, which shows the cases where different SSBs correspond to different transmission times and the same random access preamble.

[0160] Table 9

[0161]

[0162] Under correspondence three, optionally, each SSB corresponds to at least one transmission opportunity. Any two SSBs corresponding to a two-step random access preamble have the same two-step random access preamble, and the transmission opportunities corresponding to any two SSBs corresponding to a two-step random access preamble are different. The number of transmission opportunities corresponding to any two SSBs corresponding to a two-step random access preamble can be equal or unequal. The two-step random access preamble and the four-step random access preamble are different.

[0163] Furthermore, no restrictions are placed on the correspondence between the four-step random access preamble, the timing of transmission, and the SSB.

[0164] For example, any two SSBs corresponding to the four-step random access preamble have the same four-step random access preamble, but the transmission timings of any two SSBs corresponding to the four-step random access preamble are different. The number of transmission timings corresponding to any two SSBs corresponding to the four-step random access preamble can be equal or unequal.

[0165] It should be understood that the configuration method for two-step RACH resources can be interchanged with the configuration method for four-step RACH resources.

[0166] For example, see Table 10, which shows the cases where SSBs of the same type of random access preamble are sent at different times and have the same random access preamble.

[0167] Table 10

[0168]

[0169] Under correspondence three, optionally, each SSB corresponds to at least one transmission opportunity. The transmission opportunities for any two SSBs corresponding to a two-step random access preamble are the same, and the random access preambles corresponding to any two SSBs are different. The number of random access preambles corresponding to any two SSBs can be equal or unequal. The transmission opportunities for two-step random access are different from those for four-step random access.

[0170] Furthermore, no restrictions are placed on the correspondence between the four-step random access preamble, the timing of transmission, and the SSB.

[0171] For example, the four-step random access transmission timings corresponding to any two SSBs of the four-step random access preamble are the same, and the random access preambles corresponding to any two SSBs of the four-step random access preamble are different. The number of random access preambles corresponding to any two SSBs of the four-step random access preamble can be equal or unequal.

[0172] For example, see Table 11, which shows the cases where SSBs of the same type of random access preamble correspond to different random access preambles and the same transmission timing.

[0173] Table 11

[0174]

[0175]

[0176] It should be understood that Tables 1 to 11 are merely illustrative examples and do not constitute any limitation on this application.

[0177] It can be seen that for correspondences one and two, the random access preamble for each SSB includes both a two-step random access preamble and a four-step random access preamble. For correspondence three, each SSB corresponds to only one of the two-step or four-step random access preamble.

[0178] In this application, in one scenario, the target random access preamble determined in S210 is selected from the two-step random access preamble configured by the network device. The following will explain how the terminal device determines the target random access preamble from the two-step random access preamble configured by the network device, in conjunction with the correspondence between RACH resources and reference signals described above.

[0179] Method A

[0180] The two-step random access preamble configured in the network device corresponds to at least one first data volume threshold, and each first data volume threshold corresponds to a second signal strength threshold. The first data volume threshold corresponding to a two-step random access preamble is the maximum amount of data that the two-step random access preamble supports.

[0181] And, the terminal device determines the random access preamble, including:

[0182] If at least one reference signal has a corresponding RSRP greater than a first signal strength threshold, a target reference signal is selected from the reference signals greater than the first signal strength threshold. If the amount of data to be transmitted is less than or equal to one of the at least one first data amount thresholds, and the RSRP of the target reference signal is greater than a target second signal strength threshold, a target random access preamble is determined from the two-step random access preamble corresponding to the target reference signal. Here, the target second signal strength threshold is the second signal strength threshold corresponding to the first data amount threshold for the amount of data to be transmitted.

[0183] In this application, the target random access preamble supports the amount of data to be transmitted. Further, the first data volume threshold corresponding to the target random access preamble is the same as the first data volume threshold corresponding to the target second signal strength threshold.

[0184] It should be understood that the RSRP corresponding to the reference signal refers to the RSRP obtained by measuring the reference signal.

[0185] The configuration of a network device with a two-step random access preamble corresponding to at least one first data volume threshold can be understood as follows: one first data volume threshold corresponds to a set of two-step random access preambles, and the two sets of two-step random access preambles corresponding to any two first data volume thresholds are different. The maximum amount of data that can be sent by the two-step random access preamble in a set of two-step random access preambles is the first data volume threshold corresponding to that set of two-step random access preambles.

[0186] It should be understood that there is a correspondence between random access preambles and PUSCH resources. One PUSCH resource corresponds to the size of a maximum data block size, i.e., the maximum TBS. We can consider the random access preamble to correspond to the TBS, and this means that when the amount of data to be sent is less than (or less than or equal to) the TBS, the random access preamble corresponding to that TBS can be used. Therefore, the amount of data supported by a random access preamble refers to the TBS of the PUSCH resource corresponding to that random access preamble.

[0187] In this application, at least one reference signal is an SSB set or a CSI-RS set configured by the network device. The first data volume threshold corresponding to the SSB set and the first data volume threshold corresponding to the CSI-RS set can be configured by the network device through the configuration information. Alternatively, the first data volume threshold corresponding to the SSB set and the first data volume threshold corresponding to the CSI-RS set can be determined based on the modulation and coding scheme (MCS) of the PUSCH resources configured by the network device through the configuration information and the size of the PUSCH frequency domain resources. It should be understood that PUSCH resources are resources used to transmit data to be transmitted. The second signal strength threshold corresponding to the SSB set and the second signal strength threshold corresponding to the CSI-RS set can be configured by the network device through the configuration information, but this application does not limit this. The second signal strength threshold corresponding to the SSB set and the second signal strength threshold corresponding to the CSI-RS set can be equal or unequal. Similarly, the first signal strength threshold corresponding to the SSB set and the first signal strength threshold corresponding to the CSI-RS set can be equal or unequal. The first signal strength threshold is less than the second signal strength threshold. The first signal strength threshold can be a condition for selecting the four-step RACH random access preamble in the prior art or a condition for selecting the SSB in the prior art; see the prior art for details. It should be understood that the description of any concept, word, or term herein also applies to any of the following methods; therefore, when describing other methods for determining the target random access preamble below, the same concepts, words, or terms will not be described again.

[0188] In this application, PUSCH resources can be configured using PUSCH resource configuration information. This information may include at least one of the following: time-domain and frequency-domain PUSCH resources, demodulation reference signal (DMRS), number of retransmissions, MCS, initial PUSCH transmit power, target PUSCH receive power, PUSCH transmit power ramp-up step size, and power deviation relative to the random access preamble (i.e., Δ1 hereinafter). The initial PUSCH transmit power can be the transmit power of PUSCH during the initial transmission of message A. The target PUSCH receive power is the expected receive power of PUSCH by the network device; the terminal device determines the transmit power of PUSCH for message A based on this value and path loss, etc. The ramp-up step size of PUSCH transmit power refers to the ramp-up power step size used by the terminal device during message A retransmission, such as the ramp-up step size for the PUSCH portion during retransmission when no response is received from the network device after message A has been transmitted. The power deviation relative to the random access preamble is the difference (Δ1) between the transmission power of the PUSCH portion of message A and the transmission power of the random access preamble (i.e., TP in the following text). Optionally, during the initial transmission of message A, the transmission power of the PUSCH portion of message A is determined based on this deviation and the transmission power of the random access preamble portion of message A. The transmission power of the random access preamble portion of message A is determined based on path loss and the target received power of the random access preamble portion of message A configured by the network equipment. For ease of understanding, the first signal strength threshold corresponding to the SSB set is denoted as: First SSB-RSRP Threshold; the first signal strength threshold corresponding to the CSI-RS set is denoted as: First CSI-RS-RSRP Threshold; the second signal strength threshold corresponding to the SSB set is denoted as: Second SSB-RSRP Threshold; and the second signal strength threshold corresponding to the CSI-RS set is denoted as: Second CSI-RS-RSRP Threshold. It is understood that the second signal strength threshold can be a condition for selecting the two-step RACH random access preamble or a condition for selecting the SSB in this application.

[0189] The following explanation uses 1 and 2 as examples to illustrate method A.

[0190] (1) The number of the first data volume threshold is 1.

[0191] For ease of understanding, the first data volume threshold configured when the number of first data volume thresholds is 1 will be denoted as TBS#1. Specifically, the terminal device can first determine whether there is an SSB in the configured SSB set whose corresponding RSRP is greater than the first SSB-RSRP threshold. If so, it can randomly select an SSB from the corresponding SSBs whose RSRP is greater than the first SSB-RSRP threshold and use the selected SSB as the target SSB.

[0192] Then, the terminal device determines whether the amount of data to be transmitted is less than or equal to TBS#1. If the amount of data to be transmitted is greater than TBS#1, it means that two-step random access cannot be performed. If the amount of data to be transmitted is less than or equal to TBS#1, the terminal device determines whether the RSRP of the target SSB is greater than the second SSB-RSRP threshold. If the RSRP of the target SSB is greater than the second SSB-RSRP threshold, it determines whether the random access preamble corresponding to the target SSB includes a two-step random access preamble that meets the conditions. If it does, at least one of the two-step random access preambles that meets the conditions corresponding to the target SSB can be determined as the target random access preamble.

[0193] In methods A to D, a two-step random access preamble that meets the conditions refers to a two-step random access preamble that supports the amount of data to be transmitted, or a two-step random access preamble whose corresponding first data amount threshold is the first data amount threshold corresponding to the target second signal strength threshold.

[0194] It should be understood that when the number of the first data volume thresholds is 1, the first data volume threshold corresponding to the data volume to be transmitted is TBS#1, the target second signal strength threshold is the second SSB-RSRP threshold, the two-step random access preamble that meets the conditions is, and the maximum supported data volume is the two-step random access preamble of TBS#1.

[0195] It should also be understood that the amount of data to be transmitted supported by a two-step random access preamble can be understood as the first data volume threshold corresponding to the two-step random access preamble being greater than or equal to the amount of data to be transmitted.

[0196] (2) The number of the first data volume threshold is 2

[0197] For ease of understanding, the two first data volume thresholds when the number of first data volume thresholds is 2 will be denoted as TBS#1 and TBS#2, respectively. TBS#1 < TBS#2. TBS#1 corresponds to the second SSB-RSRP threshold #1, and TBS#2 corresponds to the second SSB-RSRP threshold #2.

[0198] Specifically, similar to when the number of the first data volume threshold is 1, the terminal device can first determine whether there is an SSB with a corresponding RSRP greater than the first SSB-RSRP threshold in the configured SSB set. If there is, it can randomly select an SSB from the corresponding SSB with an RSRP greater than the first SSB-RSRP threshold and use the selected SSB as the target SSB.

[0199] Then, the terminal device determines whether the amount of data to be transmitted is less than or equal to TBS#1, or whether it is less than or equal to TBS#2.

[0200] If the amount of data to be transmitted is greater than TBS#2, it means that two-step random access cannot be performed.

[0201] If the amount of data to be transmitted is less than or equal to TBS#1, the terminal device determines whether the RSRP of the target SSB is greater than the second SSB-RSRP threshold #1. If the RSRP of the target SSB is greater than the second SSB-RSRP threshold #1, it determines whether the random access preamble corresponding to the target SSB includes a two-step random access preamble that meets the conditions. If it does, at least one random access preamble that meets the conditions among the two-step random access preambles corresponding to the target SSB can be determined as the target random access preamble. For example, assuming that the two-step random access preambles corresponding to TBS#1 are preamble group #1 and the two-step random access preambles corresponding to TBS#2 are preamble group #2, then the target random access preamble can be a random access preamble in preamble group #1 or a random access preamble in preamble group #2. Preferably, the target random access preamble is a random access preamble selected from preamble group #1.

[0202] Alternatively, if the amount of data to be transmitted is less than or equal to TBS#2 and greater than TBS#1, the terminal device determines whether the RSRP of the target SSB is greater than the second SSB-RSRP threshold #2. If the RSRP of the target SSB is greater than the second SSB-RSRP threshold #2, it determines whether the random access preamble corresponding to the target SSB includes a two-step random access preamble that meets the conditions. If it does, then at least one random access preamble that meets the conditions among the two-step random access preambles corresponding to the target SSB can be determined as the target random access preamble. Here, the target random access preamble can only be the random access preamble in preamble group #2.

[0203] It should be understood that if the number of first data volume thresholds is greater than or equal to 2, assuming that the at least one first data volume threshold is in ascending order as TBS#1, TBS#2, TBS#3, ..., and the second signal strength threshold corresponding to the at least one first data volume threshold is the second SSB-RSRP threshold #1, the second SSB-RSRP threshold #2, the second SSB-RSRP threshold #3, ..., and the second signal strength threshold corresponding to any first data volume threshold TBS#i is the second SSB-RSRP threshold #i, then if the amount of data to be transmitted is less than or equal to TBS#1, the first data volume threshold corresponding to the amount of data to be transmitted is TBS#1, and the target second signal strength threshold is the second SSB-RSRP threshold #1. If the amount of data to be transmitted is greater than TBS#i and less than or equal to TBS#(i+1), the first data volume threshold corresponding to the amount of data to be transmitted is TBS#(i+1), and the target second signal strength threshold is the second SSB-RSRP threshold #(i+1). For example, when the number of first data volume thresholds is 2, if the amount of data to be transmitted is less than TBS#1, then the first data volume threshold corresponding to the amount of data to be transmitted is TBS#1, and the target second signal strength threshold is the second SSB-RSRP threshold #1. If the amount of data to be transmitted is greater than TBS#1 and less than or equal to TBS#2, then the first data volume threshold corresponding to the amount of data to be transmitted is TBS#2, and the target second signal strength threshold is the second SSB-RSRP threshold #2.

[0204] It should be understood that this article only uses SSB as the reference signal for illustration. When the reference signal is CSI-RS, a similar method can be used to determine the target random access preamble, which will not be elaborated here.

[0205] Method B

[0206] The two-step random access preamble configured in the network device corresponds to at least one first data volume threshold, and each first data volume threshold corresponds to a second signal strength threshold. The first data volume threshold corresponding to a two-step random access preamble is the maximum amount of data that the two-step random access preamble supports.

[0207] And, the terminal device determines the random access preamble, including:

[0208] If the amount of data to be transmitted is less than or equal to one of the at least one first data amount thresholds, and if there is a reference signal among the at least one reference signal whose corresponding RSRP is greater than the target second signal strength threshold, a target reference signal is selected from the reference signals whose corresponding RSRP is greater than the second signal strength threshold; the target random access preamble is determined from the two-step random access preamble corresponding to the target reference signal. The definition of the target second signal strength threshold can refer to method A.

[0209] Optionally, the target random access preamble supports the amount of data to be transmitted. Further, the first data volume threshold corresponding to the target random access preamble is the first data volume threshold corresponding to the target second signal strength threshold.

[0210] Here, we will take the number of the first data volume threshold as 1 and 2 as examples to explain method B.

[0211] (1) The number of the first data volume threshold is 1.

[0212] Specifically, the terminal device can first determine whether the amount of data to be transmitted is less than or equal to TBS#1. If the amount of data to be transmitted is less than or equal to TBS#1, the terminal device determines whether there exists an SSB in the SSB set whose RSRP is greater than the second SSB-RSRP threshold. If so, it can randomly select an SSB from the SSBs whose RSRP is greater than the second SSB-RSRP threshold as the target SSB. Next, the terminal device determines whether the random access preamble corresponding to the target SSB includes a two-step random access preamble that meets the conditions. If so, it can determine at least one random access preamble that meets the conditions from the two-step random access preamble corresponding to the target SSB as the target random access preamble.

[0213] (2) The number of the first data volume threshold is 2

[0214] Specifically, the terminal device can first determine whether the amount of data to be transmitted is less than or equal to TBS#1, or whether it is less than or equal to TBS#2. If the amount of data to be transmitted is less than or equal to TBS#1, the terminal device determines whether there exists an SSB in the SSB set whose RSRP is greater than the second SSB-RSRP threshold #1. If so, it can randomly select an SSB from the SSBs whose RSRP is greater than the second SSB-RSRP threshold #1 as the target SSB. Next, the terminal device determines whether the random access preamble corresponding to the target SSB includes a two-step random access preamble that meets the conditions. If so, it can determine at least one random access preamble that meets the conditions among the two-step random access preambles corresponding to the target SSB as the target random access preamble. Alternatively, if the amount of data to be transmitted is less than or equal to TBS#2 and greater than TBS#1, the terminal device determines whether there exists an SSB in the SSB set whose RSRP is greater than the second SSB-RSRP threshold #2. If so, it can randomly select an SSB as the target SSB from among the SSBs whose RSRP is greater than the second SSB-RSRP threshold #2. Next, the terminal device determines whether the random access preamble corresponding to the target SSB includes a two-step random access preamble that meets the conditions. If so, it can determine at least one random access preamble that meets the conditions from among the two-step random access preambles corresponding to the target SSB as the target random access preamble. The difference between method B and method A is that method B can directly select the target SSB from SSBs greater than the second SSB-RSRP threshold, while method A requires first selecting the target SSB from SSBs greater than the first SSB-RSRP threshold. Compared to method A, method B is more efficient.

[0215] For methods A and B, based on the correspondence between the reference signal and RACH resources described above, if a target SSB exists, and if the correspondence between the reference signal and RACH resources is correspondence one or correspondence two, it is highly likely that the target random access preamble can be determined. If a target SSB exists, and if the correspondence between the reference signal and RACH resources is correspondence three, it may not be possible to determine the target random access preamble. For example, if the correspondence between the reference signal and RACH resources is shown in Table 7, and the selected target SSB is SSB with ID 2, since SSB with ID 2 only corresponds to four-step random access preambles, the target random access preamble cannot be determined, or in other words, the target random access preamble does not exist.

[0216] Method C

[0217] The two-step random access preamble configured in the network device corresponds to at least one first data volume threshold, and each first data volume threshold corresponds to a second signal strength threshold. The first data volume threshold corresponding to a two-step random access preamble is the maximum amount of data that the two-step random access preamble supports.

[0218] And, the terminal device determines the random access preamble, including:

[0219] If at least one reference signal has a corresponding RSRP greater than a first signal strength threshold, and if the amount of data to be transmitted is less than or equal to one of the at least one first data amount thresholds, and if among the reference signals with corresponding RSRP greater than the first signal strength thresholds there exists a reference signal with a corresponding RSRP greater than a target second signal strength threshold, a target reference signal is determined from the reference signals with corresponding RSRP greater than the target second signal strength threshold, and at least one two-step random access preamble satisfying the conditions in the target reference signal is determined as the target random access preamble. The target reference signal can be any random access preamble among the reference signals with corresponding RSRP greater than the target second signal strength threshold, including reference signals with two-step random access preambles satisfying the conditions. The definition of the target second signal strength threshold can refer to method A.

[0220] Here, we will also take the number of the first data volume threshold as 1 and 2 as examples to explain method C.

[0221] (1) The number of the first data volume threshold is 1.

[0222] Specifically, the terminal device can first determine whether the configured SSB set includes a first set, and whether the amount of data to be transmitted is less than or equal to TBS#1, and whether any SSB in the first set has an RSRP greater than the first SSB-RSRP threshold. If the first set exists in the SSB set, and the amount of data to be transmitted is less than or equal to TBS#1, the terminal device determines whether there exists a corresponding SSB in the first set with an RSRP greater than the second SSB-RSRP threshold. If so, it then determines whether the random access preambles corresponding to these SSBs with RSRP greater than the second SSB-RSRP threshold include a two-step random access preamble that meets the conditions. If so, it can randomly select an SSB whose corresponding random access preamble includes a two-step random access preamble that meets the conditions as the target SSB, and determine at least one random access preamble that meets the conditions among the two-step random access preambles corresponding to the target SSB as the target random access preamble.

[0223] (2) The number of the first data volume threshold is 2

[0224] Specifically, the terminal device can first determine whether the configured SSB set includes the first set. If it does, it can then determine whether the amount of data to be transmitted is less than or equal to TBS#1, or whether it is less than or equal to TBS#2.

[0225] If the amount of data to be transmitted is less than or equal to TBS#1, the terminal device determines whether there exists an SSB with an RSRP greater than the second SSB-RSRP threshold #1 among the SSBs in the SSB set whose RSRP is greater than the first SSB-RSRP threshold #1. If so, it then determines whether the random access preambles corresponding to these SSBs with RSRP greater than the second SSB-RSRP threshold #1 include a two-step random access preamble that meets the conditions. If so, it can randomly select an SSB whose random access preamble includes a two-step random access preamble that meets the conditions as the target SSB, and determine at least one random access preamble that meets the conditions among the two-step random access preambles corresponding to the target SSB as the target random access preamble.

[0226] Alternatively, if the amount of data to be transmitted is less than or equal to TBS#2 and greater than TBS#1, the terminal device determines whether there exists an SSB with an RSRP greater than the second SSB-RSRP threshold #2 among the SSBs in the SSB set whose RSRP is greater than the first SSB-RSRP threshold #2. If so, it then determines whether the random access preambles corresponding to these SSBs with RSRP greater than the second SSB-RSRP threshold #2 include a two-step random access preamble that meets the conditions. If so, it can randomly select an SSB whose corresponding random access preamble includes a two-step random access preamble that meets the conditions as the target SSB, and determine at least one random access preamble that meets the conditions among the two-step random access preambles corresponding to the target SSB as the target random access preamble.

[0227] Method D

[0228] The two-step random access preamble configured in the network device corresponds to at least one first data volume threshold, and each first data volume threshold corresponds to a second signal strength threshold. The first data volume threshold corresponding to a two-step random access preamble is the maximum amount of data that the two-step random access preamble supports.

[0229] And, the terminal device determines the random access preamble, including:

[0230] If the amount of data to be transmitted is less than or equal to one of the at least one first data amount thresholds, and if there is a reference signal among the at least one reference signal whose corresponding RSRP is greater than the target second signal strength threshold, a target reference signal is determined from the reference signals whose corresponding RSRP is greater than the target second signal strength threshold, and at least one two-step random access preamble in the target reference signal that meets the conditions is determined as the target random access preamble. The target reference signal can be any reference signal among the reference signals whose corresponding RSRP is greater than the target second signal strength threshold, including reference signals whose corresponding random access preambles include two-step random access preambles that meet the conditions. The definition of the target second signal strength threshold can refer to method A.

[0231] Here, we will also take the number of the first data volume threshold as 1 and 2 as examples to explain method D.

[0232] (1) The number of the first data volume threshold is 1.

[0233] Specifically, the terminal device can first determine whether the amount of data to be transmitted is less than or equal to TBS#1. If the amount of data to be transmitted is less than or equal to TBS#1, the terminal device then determines whether there exists an SSB in the SSB set whose RSRP is greater than the second SSB-RSRP threshold. If so, it further determines whether the random access preambles corresponding to these SSBs with RSRP greater than the second SSB-RSRP threshold include two-step random access preambles. If so, it can randomly select an SSB whose corresponding random access preamble includes two-step random access preambles that meet the conditions as the target SSB, and determine at least one random access preamble that meets the conditions among the two-step random access preambles corresponding to the target SSB as the target random access preamble.

[0234] (2) The number of the first data volume threshold is 2

[0235] Specifically, the terminal device can first determine whether the amount of data to be transmitted is less than or equal to TBS#1, or whether it is less than or equal to TBS#2. If the amount of data to be transmitted is less than or equal to TBS#1, the terminal device determines whether there is an SSB in the SSB set whose RSRP is greater than the second SSB-RSRP threshold #1. If so, it then determines whether the random access preambles corresponding to these SSBs whose RSRP is greater than the second SSB-RSRP threshold #1 include a two-step random access preamble that meets the conditions. If so, it can randomly select an SSB whose corresponding random access preamble includes a two-step random access preamble that meets the conditions as the target SSB, and determine at least one random access preamble that meets the conditions among the two-step random access preambles corresponding to the target SSB as the target random access preamble. Alternatively, if the amount of data to be transmitted is less than or equal to TBS#2 and greater than TBS#1, the terminal device determines whether there is an SSB in the SSB set whose RSRP is greater than the second SSB-RSRP threshold #2. If so, it then determines whether the random access preambles corresponding to these SSBs whose RSRP is greater than the second SSB-RSRP threshold #2 include a two-step random access preamble that meets the conditions. If so, it can randomly select an SSB whose corresponding random access preamble includes a two-step random access preamble that meets the conditions as the target SSB, and determine at least one random access preamble that meets the conditions among the two-step random access preambles corresponding to the target SSB as the target random access preamble.

[0236] The difference between method D and method C is that method D can directly determine the SSBs in the SSB set that are greater than the second SSB-RSRP threshold, while method C requires first identifying all SSBs in the SSB set that are greater than the first SSB-RSRP threshold, and then identifying the SSBs greater than the second SSB-RSRP threshold from among all SSBs greater than the first SSB-RSRP threshold. Compared to method C, method D is more efficient.

[0237] For methods C and D, based on the correspondence between the reference signal and RACH resources described above, if the correspondence is either correspondence one or correspondence two, and if there is an SSB greater than the second SSB-RSRP threshold, the target random access preamble may be determined. If the correspondence is correspondence three, and if among the SSBs greater than the second SSB-RSRP threshold there is at least one corresponding random access preamble including a two-step random access preamble, the target random access preamble may be determined.

[0238] Method E

[0239] The two-step random access preamble configured in the network device corresponds to at least one first data volume threshold, and each first data volume threshold corresponds to a PL1, where PL1 is a first path loss threshold. The first data volume threshold corresponding to a two-step random access preamble is the maximum amount of data that the two-step random access preamble supports.

[0240] And, the terminal device determines the random access preamble, including:

[0241] If the RSRP of at least one reference signal is greater than a first signal strength threshold, a target reference signal is selected from the reference signals greater than the first signal strength threshold. If the amount of data to be transmitted is less than or equal to one of the at least one first data amount thresholds, and the path loss corresponding to the target reference signal is less than the target PL1, a target random access preamble is determined from the two-step random access preambles corresponding to the target reference signal. Optionally, the target random access preamble supports the amount of data to be transmitted. Further, the first data amount threshold corresponding to the target random access preamble is the first data amount threshold corresponding to the target second signal strength threshold.

[0242] In this application, PL1 = PCMAX - TP - Δ1, where PL1 is the first path loss threshold, PCMAX is the maximum transmit power of the terminal equipment in the cell performing random access, TP is the target receive power of the two-step random access preamble, and Δ1 is the power deviation between the data to be transmitted and the two-step random access preamble. One or more of PCMAX, TP, and Δ1 can be configured through the configuration information or agreed upon by the protocol, but this application does not limit this. The target PL1 is the PL1 corresponding to the first data volume threshold corresponding to the amount of data to be transmitted.

[0243] For example, path loss can be the difference between the RSRP of the reference signal transmitted by the network device and the RSRP measured by the terminal device. The RSRP of the reference signal transmitted by the network device can be configured by the network device for the terminal device. Alternatively, the network device can directly configure PL1, or PL1 can be specified by the protocol.

[0244] The following explanation uses 1 and 2 as examples to illustrate method E.

[0245] (1) The number of the first data volume threshold is 1.

[0246] Specifically, the terminal device can first determine whether there is an SSB in the configured SSB set whose RSRP is greater than the first SSB-RSRP threshold. If so, it can randomly select an SSB from the SSBs whose RSRP is greater than the first SSB-RSRP threshold and use the selected SSB as the target SSB.

[0247] Then, the terminal device determines whether the amount of data to be transmitted is less than or equal to TBS#1. If the amount of data to be transmitted is greater than TBS#1, it means that two-step random access cannot be performed. If the amount of data to be transmitted is less than or equal to TBS#1, the terminal device determines whether the path loss corresponding to the target SSB is less than the target PL1. If the path loss corresponding to the target SSB is less than the target PL1, it determines whether the random access preamble corresponding to the target SSB includes a two-step random access preamble that meets the conditions. If it does, at least one random access preamble that meets the conditions among the two-step random access preambles corresponding to the target SSB can be determined as the target random access preamble.

[0248] In modes E and F, a two-step random access preamble that meets the conditions refers to a two-step random access preamble that supports the amount of data to be transmitted, or a two-step random access preamble whose corresponding first data amount threshold is the first data amount threshold corresponding to the target PL1.

[0249] It should be understood that when the number of first data volume thresholds is 1, the first data volume threshold corresponding to the data volume to be transmitted is TBS#1, the target PL1 is a unique PL1, the two-step random access preamble that meets the conditions is, and the maximum supported data volume to be sent is the two-step random access preamble of TBS#1.

[0250] (2) The number of the first data volume threshold is 2

[0251] For ease of understanding, the PL1 corresponding to TBS#1 will be referred to as PL1#1 in the following text, and the PL1 corresponding to TBS#2 will be referred to as PL1#2.

[0252] Specifically, the terminal device can first determine whether there is an SSB in the configured SSB set whose RSRP is greater than the first SSB-RSRP threshold. If so, it can randomly select an SSB from the SSBs whose RSRP is greater than the first SSB-RSRP threshold and use the selected SSB as the target SSB.

[0253] Then, the terminal device determines whether the amount of data to be transmitted is less than or equal to TBS#1, or whether it is less than or equal to TBS#2.

[0254] If the amount of data to be transmitted is greater than TBS#2, it means that two-step random access cannot be performed.

[0255] If the amount of data to be transmitted is less than or equal to TBS#1, the terminal device determines whether the path loss corresponding to the target SSB is less than PL1#1. If the path loss corresponding to the target SSB is less than PL1#1, it determines whether the random access preamble corresponding to the target SSB includes a two-step random access preamble that meets the conditions. If it does, at least one random access preamble that meets the conditions among the two-step random access preambles corresponding to the target SSB can be determined as the target random access preamble.

[0256] Alternatively, if the amount of data to be transmitted is less than or equal to TBS#2 and greater than TBS#1, the terminal device determines whether the path loss corresponding to the target SSB is less than PL1#2. If the path loss corresponding to the target SSB is less than PL1#2, it determines whether the random access preamble corresponding to the target SSB includes a two-step random access preamble. If it does, at least one random access preamble that meets the conditions among the two-step random access preambles corresponding to the target SSB can be determined as the target random access preamble.

[0257] It should be understood that if the number of first data volume thresholds is greater than or equal to 2, assuming that the at least one first data volume threshold is in ascending order as TBS#1, TBS#2, TBS#3, ..., and the PL1 corresponding to the at least one first data volume threshold is PL1#1, PL1#2, PL1#3, ..., and the PL1 corresponding to any first data volume threshold TBS#i is PL1#i, then if the data volume to be transmitted is greater than 0 and less than or equal to TBS#1, the first data volume threshold corresponding to the data volume to be transmitted is TBS#1, and the target PL1 is PL1#1. If the data volume to be transmitted is greater than TBS#i and less than or equal to TBS#(i+1), the first data volume threshold corresponding to the data volume to be transmitted is TBS#(i+1), and the target PL1 is PL1#(i+1). For example, when the number of first data volume thresholds is 2, if the data volume to be transmitted is less than TBS#1, the first data volume threshold corresponding to the data volume to be transmitted is TBS#1, and the target PL1 is PL1#1. If the amount of data to be transmitted is greater than TBS#1 and less than or equal to TBS#2, then the first data volume threshold corresponding to the amount of data to be transmitted is TBS#2, and the target PL1 is PL1#2.

[0258] Method F

[0259] The two-step random access preamble configured in the network device corresponds to at least one first data volume threshold, and each first data volume threshold corresponds to a PL1, where PL1 is a first path loss threshold. The first data volume threshold corresponding to a two-step random access preamble is the maximum amount of data that the two-step random access preamble supports.

[0260] And, the terminal device determines the random access preamble, including:

[0261] If the RSRP of at least one reference signal is greater than a first signal strength threshold, and if the amount of data to be transmitted is less than or equal to one of the at least one first data amount thresholds, and if among the reference signals whose RSRP is greater than the first signal strength threshold there exists a reference signal with a path loss less than the target PL1, a target reference signal is determined from the reference signals whose RSRP is greater than the first signal strength threshold and whose path loss is less than the target PL1, and at least one two-step random access preamble that meets the conditions in the target reference signal is determined as the target random access preamble. The target reference signal can be any random access preamble among the reference signals whose RSRP is greater than the first signal strength threshold and whose path loss is less than the target PL1, including reference signals with two-step random access preambles that meet the conditions. The definition of the target PL1 is given in Method E.

[0262] As is understandable, method F is similar to method C, so I will not go into details here.

[0263] Method G

[0264] The terminal determines the random access preamble, including:

[0265] If at least one of the reference signals has a corresponding RSRP greater than the first signal strength threshold, select a target reference signal from the reference signals with corresponding RSRP greater than the first signal strength threshold, and determine whether the first set of random access preamble has been configured.

[0266] If a first set of random access preambles is configured, and the amount of data to be transmitted is greater than the second data amount threshold, and the path loss corresponding to the target reference signal is less than PL2, then the target random access preamble is determined from the random access preambles belonging to the first set of random access preambles corresponding to the target reference signal; or

[0267] If a first set of random access preambles is configured, and the amount of data to be transmitted is less than or equal to a second data amount threshold, the target random access preamble is determined from the random access preambles belonging to the second set of random access preambles corresponding to the target reference signal; or

[0268] If the first set of random access preambles is configured, and the path loss corresponding to the target reference signal is greater than or equal to PL2, the target random access preamble is determined from the random access preambles belonging to the second set of random access preambles corresponding to the target reference signal.

[0269] The first set of random access preambles supports a data transmission volume greater than a second data volume threshold, while the second set of random access preambles supports a maximum data transmission volume equal to the second data volume threshold. The first and second sets of random access preambles constitute a two-step random access preamble. Wherein, PL2 = PCMAX - TP - Δ1 - Δ2, PL2 is the second path loss threshold, PCMAX is the maximum transmit power of the terminal equipment in the cell performing random access, TP is the target receive power of the two-step random access preamble, Δ1 is the power deviation between the data to be transmitted and the two-step random access preamble, and Δ2 is the power deviation between the first and second sets of random access preambles. The first set of random access preambles, the second set of random access preambles, PCMAX, TP, Δ1, and Δ2 can be configured using the configuration information, but this application does not limit this. The first and second sets of random access preambles constitute a two-step random access preamble.

[0270] In this application, at least one reference signal is an SSB set or a CSI-RS set configured by the network device. The second data volume threshold corresponding to the SSB set and the second data volume threshold corresponding to the CSI-RS set can be configured by the network device through the configuration information. Alternatively, the second data volume threshold corresponding to the SSB set and the second data volume threshold corresponding to the CSI-RS set can be determined by the size of the MCS and PUSCH frequency domain resources of the PUSCH resources configured by the network device through the configuration information. It should be understood that the description of any concept, word, or term herein also applies to any of the following methods; therefore, when describing other methods for determining the target random access preamble below, the same concepts, words, or terms will not be described again.

[0271] Taking SSB as an example, in short, if there is an SSB in the set of SSBs configured by the network device with a corresponding RSRP greater than the first signal strength threshold, then an SSB can be randomly selected from the SSBs with RSRP greater than the first signal strength threshold as the target SSB. Next, the terminal device determines whether a first set of random access preambles is configured. If a first set of random access preambles is configured, and conditions (a) and (b) are met, then the target random access preamble is determined from the random access preambles belonging to the first set of random access preambles corresponding to the target reference signal. If either condition (a) or (b) is not met, then the target random access preamble is determined from the random access preambles belonging to the second set of random access preambles corresponding to the target reference signal. Wherein, condition (a): the amount of data to be transmitted is greater than the second data amount threshold; condition (b): the path loss corresponding to the target reference signal is less than PL2.

[0272] Method H

[0273] The terminal determines the random access preamble, including:

[0274] If at least one of the reference signals has a corresponding RSRP greater than the first signal strength threshold, determine whether a first set of random access preambles has been configured. If a first set of random access preambles has been configured, and conditions (c) and (d) are met, then the target random access preamble is determined from the random access preambles belonging to the first set of random access preambles corresponding to the target reference signal. If either condition (c) or (d) is not met, then the target random access preamble is determined from the random access preambles belonging to the second set of random access preambles corresponding to the target reference signal. Wherein, condition (c) is: the amount of data to be transmitted is greater than the second data amount threshold; and condition (d) is: among the reference signals whose RSRP is greater than the first signal strength threshold, there is a corresponding reference signal with a path loss less than PL2.

[0275] Method I

[0276] The terminal determines the random access preamble, including:

[0277] If at least one of the reference signals has a corresponding RSRP greater than the first signal strength threshold, select a target reference signal from the reference signals with corresponding RSRP greater than the first signal strength threshold, and determine whether the first set of random access preamble has been configured.

[0278] If a first set of random access preambles is configured, and the amount of data to be transmitted is greater than the second data amount threshold, and the data to be transmitted is carried through the common control channel (CCCH), the target random access preamble is determined from the random access preambles belonging to the first set of random access preambles corresponding to the target reference signal.

[0279] If a first set of random access preambles is configured, and the amount of data to be transmitted is less than or equal to a second data amount threshold, the target random access preamble is determined from the random access preambles belonging to the second set of random access preambles corresponding to the target reference signal; or,

[0280] If the first set of random access preambles is configured, and the data to be transmitted is not carried through CCCH, the target random access preamble is determined from the random access preambles belonging to the second set of random access preambles corresponding to the target reference signal.

[0281] In modes H and I, further, if the terminal device determines that the first group of random access preambles is not configured, the target random access preamble is determined from the random access preamble belonging to the second group of random access preambles corresponding to the target reference signal.

[0282] Optionally, as an embodiment of this application, if the random access preamble corresponding to the target reference signal does not include a two-step random access preamble, or does not include a two-step random access preamble that meets the conditions, the terminal device can determine the target random access preamble from the four-step random access preamble configured by the network device. For example, the terminal device can determine the four-step random access preamble that supports the amount of data to be transmitted from the random access preamble corresponding to the target reference signal as the target random access preamble. Furthermore, the method for selecting the four-step random access preamble can also refer to existing methods, such as selecting based on measured path loss and the amount of data to be transmitted, or based on the amount of data triggered by CCCH.

[0283] The preceding text described how to determine the target random access preamble when it is a two-step random access preamble. When the target random access preamble is a four-step random access preamble, the method for determining it can be found in existing technologies and will not be repeated here.

[0284] Optionally, before the terminal device determines the target random access preamble, the terminal device may determine that two-step random access is required for random access.

[0285] For example, a terminal device may determine whether two-step random access is required based on one or a combination of the following factors:

[0286] (1) Load information for two-step random access and four-step random access. For example, if the load on two-step random access is low, then it is determined that two-step random access should be used for random access;

[0287] (2) The reason for the uplink initiated by the terminal device. For example, if the uplink priority is high, then a two-step random access method is required. For example, in the case of an emergency call, a two-step random access method is required.

[0288] (3) Quality of service information for uplink services. For example, for inactive terminal devices, for uplink services with high quality of service levels, it is determined that two-step random access is required.

[0289] Optionally, as an embodiment of this application, the terminal device may determine the random access type after determining the target SSB according to some of the above methods. For example, if the target SSB includes both a two-step random access preamble and a four-step random access preamble, the terminal device may determine whether to use two-step random access or four-step random access according to one or more of the above-listed (1) to (3).

[0290] Optionally, as an embodiment of this application, the terminal device performs random access using the target random access preamble, including:

[0291] The terminal device determines the next available transmission opportunity from the transmission opportunities corresponding to the target reference signal; and performs random access using the random access preamble at the available transmission opportunity.

[0292] By using the methods described above for determining the random access preamble, a target reference signal can be determined. This target reference signal corresponds to at least one transmission opportunity (or available transmission opportunity). The terminal device can select the next transmission opportunity, that is, the transmission opportunity that is closest to the current time, and transmit the selected target random access preamble and the data to be transmitted at the transmission opportunity to perform two-step random access.

[0293] The following describes the possible application scenarios of method 400.

[0294] In one implementation, method 400 can be used for the initial data transmission. That is, the random access performed in S420 is used for the initial data transmission. It should be understood that the random access performed in S420 can be either a two-step random access or a four-step random access.

[0295] Optionally, in the scenario where method 400 is used for initial data transmission, the method may further include: performing a two-step random access if the random access fails.

[0296] In other words, if the random access used for the initial data transmission fails, the terminal device will perform a two-step random access process again.

[0297] When the terminal device performs two-step random access again, it can select a random access preamble again using the method described above for determining the target random access preamble. Alternatively, the terminal device can directly use the target random access preamble used during the initial transmission, or the random access preamble group to which the target random access preamble is located (e.g., the first group of random access preambles or the second group of random access preambles), or any random access preamble that meets the conditions in the two-step random access preambles included in the target SSB, to perform random access.

[0298] Optionally, in the scenario where method 400 is used for initial data transmission, if the random access fails and the terminal device does not receive the RACH resource for backtracking four-step random access as indicated by the network device, then two-step random access is performed again.

[0299] Optionally, in the scenario where method 400 is used for initial data transmission, the method may further include: performing a four-step random access or falling back to a four-step random access if the random access fails.

[0300] When performing a four-step random access procedure or falling back to a four-step random access procedure, the terminal device can first determine the random access preamble used for the four-step random access procedure.

[0301] Optionally, the terminal device may use the method of selecting a random access preamble when transmitting message 3 or PUSCH for the first time in the prior art to determine the random access preamble used for four-step random access, or it may use the method of selecting a random access preamble when transmitting message 3 or PUSCH for the first time in the prior art to determine the random access preamble used for four-step random access. For details, please refer to the prior art, which will not be elaborated here.

[0302] Optionally, in scenarios where the initial transmission is a four-step random access, the terminal device can also directly use the target random access preamble used during the initial transmission, or any random access preamble in the random access preamble group (such as group A or group B in the prior art) to perform random access.

[0303] In this application, the network device can instruct the terminal device to fall back to four-step random access for sending the random access preamble. Alternatively, the terminal device can fall back to four-step random access for sending the random access preamble if it does not receive a response message from the network device or based on the network device's load. For example, the network device sends load status information for two-step or four-step random access; if the load of two-step random access is high, it automatically falls back to four-step random access. Conversely, if the load of four-step random access is high, it automatically falls back to two-step random access.

[0304] In this application, optionally, the reason for random access failure may be one or more of the following combinations:

[0305] The terminal device did not receive message B or message 2;

[0306] After the network device indicates the retransmission resource for the data portion, the data portion still fails to be sent successfully after N retransmissions;

[0307] After the network device indicated that it should fall back to the four-step random access, message 3 was sent, but message 3 still failed to be sent after N retransmissions.

[0308] After the network device indicated a fallback to four-step random access, the data portion of message A still failed to be sent successfully after N retransmissions;

[0309] The response message received by the terminal device contains the Preamble ID sent by the terminal device and the uplink authorization allocated for this preamble ID, but does not contain contention resolution information corresponding to this preamble.

[0310] When the terminal device receives the response message, it contains the Preamble ID sent by the terminal device and contention resolution information, but the terminal device fails to resolve the contention.

[0311] When the network device instructs to retransmit message A, the retransmission includes preamble and PUSCH, but the message is still not successfully sent after retransmission.

[0312] In another implementation, method 400 can be used for data retransmission. That is, the random access performed in S420 is used for data retransmission.

[0313] Furthermore, in the scenario where method 400 is used for data retransmission, the method may also include: performing two-step random access in the event of failure of four-step random access.

[0314] In other words, if the four-step random access for initial data transmission fails, the terminal device will then choose to perform a two-step random access.

[0315] In another implementation, if the random access operation in S420 fails, the method may further include: the terminal device receiving an indication message sent by the network device, and performing random access according to the indication message. That is, if random access fails, the terminal device performs random access again according to the indication message sent by the network device.

[0316] Specifically, in the event that random access in S420 fails, the network device can send an indication message to the terminal device. This indication message can instruct the terminal device to perform a two-step random access or a four-step random access. After receiving the indication message from the network device, if the indication message instructs the terminal device to perform a two-step random access, then the terminal device performs a two-step random access; if the indication message instructs the terminal device to perform a four-step random access, then the terminal device performs a four-step random access.

[0317] Compared to the two methods mentioned above where the terminal device decides the random access type to re-access after a failed random access, this implementation requires the network device to indicate the random access type to re-access after a failed random access.

[0318] The method provided in this application has been described above; the apparatus provided in this application will be described below.

[0319] Figure 5 This is a schematic block diagram of a communication device provided in an embodiment of this application. Figure 5 As shown, the communication device 500 may include a processing unit 510 and a transceiver unit 520.

[0320] In one possible design, the communication device 500 may correspond to the terminal device in the above method embodiments. For example, it may be a terminal device or a chip configured within a terminal device. When the communication device is a terminal device, the processing unit may be a processor, and the transceiver unit may be a transceiver. The communication device may also include a storage unit, which may be a memory. The storage unit is used to store instructions, and the processing unit executes the instructions stored in the storage unit to cause the communication device to perform the above-described method. When the communication device is a chip within a terminal device, the processing unit may be a processor, and the transceiver unit may be an input / output interface, pin, or circuit, etc. The processing unit executes the instructions stored in the storage unit to cause the communication device to perform the operations performed by the terminal device in the above-described method 400. The storage unit may be a storage unit within the chip (e.g., a register, cache, etc.), or it may be a storage unit located outside the chip within the communication device (e.g., a read-only memory, random access memory, etc.).

[0321] In one implementation, the communication device 500 may correspond to a terminal device in the method according to the embodiments of this application, and the communication device 500 may include tools for performing... Figure 4 The terminal device in the method is a unit that executes the method. Furthermore, each unit in the communication device and the other operations and / or functions described above are for the purpose of implementing... Figure 4 The corresponding process of the method in the document. Specifically, the processing unit 510 can be used to execute... Figure 4 In the method shown, S410, the transceiver unit 520 can be used to execute... Figure 4 Methods 420 and S404 are shown.

[0322] In another possible design, the communication device 500 may correspond to the network device in the above method embodiments. For example, it may be a network device or a chip configured within a network device. When the communication device is a network device, the processing unit may be a processor, and the transceiver unit may be a transceiver. The communication device may also include a storage unit, which may be a memory. The storage unit is used to store instructions, and the processing unit executes the instructions stored in the storage unit to cause the communication device to perform the above-described method. When the communication device is a chip within a network device, the processing unit may be a processor, and the transceiver unit may be an input / output interface, pin, or circuit, etc. The processing unit executes the instructions stored in the storage unit to cause the communication device to perform the operations performed by the network device in the above-described method 400. The storage unit may be a storage unit within the chip (e.g., a register, cache, etc.) or a storage unit located outside the chip within the communication device (e.g., a read-only memory, random access memory, etc.).

[0323] In one implementation, the communication device 500 may correspond to a network device in the method according to the embodiments of this application, and the communication device 500 may include functions for performing... Figure 4 The network device in the communication device 500 is a unit that executes the method. Furthermore, each unit in the communication device 500 and the other operations and / or functions described above are for the purpose of implementing... Figure 4 The corresponding process of method 400. Specifically, when the communication device 500 is used to execute... Figure 4 When method 400 is used, processing unit 510 can be used to execute... Figure 4 In the method shown, S402, the transceiver unit 420 can be used to execute... Figure 4 Methods S420 and S404 in the document.

[0324] In the above-described device embodiments, the network devices and terminal devices in the method embodiments completely correspond to each other, with corresponding modules or units executing corresponding steps. For example, the transceiver unit (transceiver) executes the sending and / or receiving steps in the method embodiments, while other steps besides sending and receiving can be executed by the processing unit (processor). The functions of specific units can be found in the corresponding method embodiments. The transceiver unit may include a sending unit and / or a receiving unit, and the transceiver may include a transmitter and / or a receiver, respectively implementing sending and receiving functions; there may be one or more processors.

[0325] It should be understood that the above division of units is only a functional division, and there may be other division methods in actual implementation.

[0326] The aforementioned terminal device or network device can be a chip. The processing unit can be implemented in hardware or software. When implemented in hardware, the processing unit can be a logic circuit, integrated circuit, etc. When implemented in software, the processing unit can be a general-purpose processor that reads software code stored in a storage unit. The storage unit can be integrated into the processor or located outside the processor and exist independently.

[0327] Figure 6 This is a schematic diagram of the structure of a terminal device 10 provided in this application. For ease of explanation, Figure 6 Only the main components of the terminal device are shown. For example... Figure 6 As shown, the terminal device 10 includes a processor, a memory, a control circuit, an antenna, and input / output devices.

[0328] The processor is primarily used to process communication protocols and data, control the entire terminal device, execute software programs, and process the data within those programs, such as supporting the terminal device in performing the actions described in the above method embodiments. The memory is primarily used to store software programs and data. The control circuit is primarily used for converting baseband signals to radio frequency (RF) signals and processing RF signals. The control circuit, along with the antenna, can also be called a transceiver, primarily used for transmitting and receiving RF signals in the form of electromagnetic waves. Input / output devices, such as touchscreens, displays, and keyboards, are primarily used to receive user input data and output data to the user.

[0329] When the terminal device is powered on, the processor can read the software program from the storage unit, interpret and execute the software program's instructions, and process the software program's data. When data needs to be transmitted wirelessly, the processor performs baseband processing on the data to be transmitted and outputs the baseband signal to the radio frequency (RF) circuit. The RF circuit then processes the baseband signal and transmits the RF signal outward as electromagnetic waves through the antenna. When data is sent to the terminal device, the RF circuit receives the RF signal through the antenna, converts the RF signal into a baseband signal, and outputs the baseband signal to the processor. The processor converts the baseband signal back into data and processes the data.

[0330] Those skilled in the art will understand that, for ease of explanation, Figure 6 Only one memory and processor are shown. In actual terminal devices, multiple processors and memories may exist. Memory can also be called storage medium or storage device, etc., and this application embodiment does not limit this.

[0331] As an optional implementation, the processor may include a baseband processor and a central processing unit (CPU). The baseband processor is mainly used to process communication protocols and communication data, while the CPU is mainly used to control the entire terminal device, execute software programs, and process the data of the software programs. Figure 6 The processor in the device integrates the functions of a baseband processor and a central processing unit (CPU). Those skilled in the art will understand that the baseband processor and CPU can also be independent processors interconnected via technologies such as buses. It will also be understood that a terminal device can include multiple baseband processors to adapt to different network standards, and multiple CPUs to enhance its processing capabilities. The various components of the terminal device can be connected via various buses. The baseband processor can also be described as a baseband processing circuit or a baseband processing chip. Similarly, the CPU can be described as a central processing circuit or a central processing chip. The function of processing communication protocols and communication data can be built into the processor or stored as a software program in a storage unit, with the processor executing the software program to implement the baseband processing function.

[0332] For example, in the embodiments of this application, the antenna and control circuit with transceiver functions can be regarded as the transceiver unit 101 of the terminal device 10, and the processor with processing functions can be regarded as the processing unit 102 of the terminal device 10. Figure 6 As shown, the terminal device 10 includes a transceiver unit 101 and a processing unit 102. The transceiver unit can also be referred to as a transceiver, transceiver device, or transceiver apparatus. Optionally, the device in the transceiver unit 101 used to implement the receiving function can be considered as a receiving unit, and the device in the transceiver unit 101 used to implement the transmitting function can be considered as a transmitting unit; that is, the transceiver unit 101 includes a receiving unit and a transmitting unit. For example, the receiving unit can also be referred to as a receiver, receiver circuit, or receiving device, and the transmitting unit can be referred to as a transmitter, transmitter, or transmitting circuit.

[0333] Figure 6 The terminal device shown can perform the various actions performed by the terminal device in the above method. Here, to avoid redundancy, its detailed description is omitted.

[0334] Figure 7 This is a schematic diagram of the structure of a network device provided in this application, which can be, for example, a base station. Figure 7 As shown, this base station can be applied to, for example... Figure 1 In the communication system shown, the functions of the network device in the above method embodiment are performed. The base station 20 may include one or more radio frequency units, such as a remote radio unit (RRU) 201 and one or more baseband units (BBUs) (also referred to as digital units (DUs)) 202. The RRU 201 may be called a transceiver unit, transceiver, transceiver circuit, or transceiver, etc., and may include at least one antenna 2011 and a radio frequency unit 2012. The RRU 201 is mainly used for transmitting and receiving radio frequency signals and converting radio frequency signals to baseband signals, for example, for transmitting the BFR configuration of the above method embodiment. The BBU 202 is mainly used for baseband processing and controlling the base station. The RRU 201 and BBU 202 may be physically arranged together or physically separated, i.e., a distributed base station.

[0335] The BBU 202 is the control center of the base station, also known as the processing unit, and is mainly used to complete baseband processing functions, such as channel coding, multiplexing, modulation, spreading, etc. For example, the BBU (processing unit) 202 can be used to control the base station to execute the operation procedures of the network equipment in the above method embodiments.

[0336] In one embodiment, the BBU 202 may consist of one or more boards. These boards can collectively support a single access-indicating radio access network (such as an LTE network), or they can each support radio access networks with different access standards (such as LTE, 5G, or other networks). The BBU 202 also includes a memory 2021 and a processor 2022. The memory 2021 stores necessary instructions and data. The processor 2022 controls the base station to perform necessary actions, such as controlling the base station to execute the network device operation procedures described in the above method embodiments. The memory 2021 and processor 2022 can serve one or more boards. That is, each board can have its own memory and processor, or multiple boards can share the same memory and processor. Furthermore, each board can also have necessary circuitry.

[0337] In addition, the network equipment is not limited to the above-mentioned form, and may also be in other forms: for example, including BBU and adaptive radio unit (ARU), or BBU and active antenna unit (AAU); it may also be customer premises equipment (CPE), or other forms, which are not limited in this application.

[0338] It should be noted that the processor in the embodiments of this application can be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method embodiments can be completed by the integrated logic circuits in the processor's hardware or by instructions in software form. The processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this application can be directly embodied in the execution of a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software modules can be located in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory; the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above methods.

[0339] It should be understood that the processor in the embodiments of this application can be a central processing unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0340] It should also be understood that the memory in the embodiments of this application can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of random access memory (RAM) are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate synchronous DRAM (DDR SDRAM), enhanced synchronous DRAM (ESDRAM), synchronous linked DRAM (SLDRAM), and direct rambus RAM (DR RAM).

[0341] According to the method provided in the embodiments of this application, this application also provides a computer program product, which includes: computer program code, which, when run on a computer, causes the computer to execute... Figure 4 The method in the illustrated embodiment.

[0342] According to the method provided in the embodiments of this application, this application also provides a computer-readable medium storing program code, which, when run on a computer, causes the computer to perform... Figure 2 The method in the illustrated embodiment.

[0343] According to the method provided in the embodiments of this application, this application also provides a system, which includes one or more terminal devices and one or more network devices as described above.

[0344] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded or executed on a computer, all or part of the processes or functions described in the embodiments of the present invention are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more sets of available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., digital versatile disc (DVD)), or a semiconductor medium. The semiconductor medium can be a solid-state drive.

[0345] It should be understood that in the various embodiments of this application, the order of the above-mentioned processes does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0346] It should also be understood that in this application, “when…”, “if” and “if” all refer to the terminal device or network device making a corresponding processing under certain objective circumstances, and are not time limits, nor do they require the terminal device or network device to make a judgment action when it implements the process, nor do they imply any other limitations.

[0347] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0348] In this document, the terms “at least one of…” or “at least one of…” or “at least one of…” refer to all or any combination of the listed items. For example, “at least one of A, B and C” can mean: A alone, B alone, C alone, A and B together, B and C together, and A, B and C together.

[0349] It should be understood that in the embodiments of this application, "B corresponding to A" means that B is associated with A, and B can be determined based on A. However, it should also be understood that determining B based on A does not mean that B is determined solely based on A; B can also be determined based on A and / or other information.

[0350] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0351] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0352] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0353] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0354] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0355] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0356] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A random access method, characterized in that, include: Determine the random access preamble from at least one two-step random access preamble; Two-step random access is performed using the determined random access preamble; If the two-step random access fails, a four-step random access is performed, wherein the random access preamble used for the four-step random access is any one of the random access preamble groups in which the random access preamble used for the two-step random access is located. Determining the random access preamble from at least one two-step random access preamble includes: If there is a reference signal with a corresponding reference signal received power (RSRP) greater than a first signal strength threshold among at least one reference signal configured in the network device, a target reference signal is selected from the reference signals with corresponding RSRP greater than the first signal strength threshold. The reference signal is a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS). Determine whether the first set of random access preambles has been configured, and the amount of data that the first set of random access preambles supports is greater than the second data amount threshold; If the first set of random access preambles is configured, and the amount of data to be transmitted is greater than the second data amount threshold, and the data to be transmitted is carried through the Common Control Channel (CCCH), the random access preamble is determined from the random access preambles belonging to the first set of random access preambles corresponding to the target reference signal; or, If the first set of random access preambles is configured, and the amount of data to be transmitted is less than or equal to the second data amount threshold, the random access preamble is determined from the random access preambles belonging to the second set of random access preambles corresponding to the target reference signal.

2. The method as described in claim 1, characterized in that, The maximum amount of data that the second set of random access preambles can support is the second data amount threshold. The first set of random access preambles and the second set of random access preambles are two-step random access preambles.

3. The method as described in claim 1 or 2, characterized in that, The method further includes: If the first set of random access preambles is not configured, the random access preamble is determined from the random access preambles belonging to the second set of random access preambles corresponding to the target reference signal.

4. The method as described in claim 1 or 2, characterized in that, The two-step random access and the four-step random access are used for the initial data transmission.

5. The method as described in claim 1 or 2, characterized in that, The method further includes: The network device receives configuration information, which configures the random access resources corresponding to the synchronization signal block (SSB). The random access resources are used to perform the two-step random access or the four-step random access.

6. A communication device, characterized in that, The apparatus includes a module for performing the method as described in any one of claims 1 to 5.

7. A communication device, characterized in that, include: A processor coupled to a memory for storing programs or instructions that, when executed by the processor, cause the apparatus to perform the method as described in any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program or instructions stored thereon, characterized in that, The computer program or instructions are executed by a processor to implement the method as described in any one of claims 1 to 5.

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