Communication method and apparatus

Abstract

The present application provides a communication method and apparatus. The method comprises: a terminal apparatus acquires a first message, and sends the first message on a plurality of random access occasions, wherein the first message comprises preamble information, the plurality of random access occasions comprise a first random access occasion and a second random access occasion, the first random access occasion is selected, on the basis of the preamble information, from among random access occasions corresponding to a first synchronization block, the second random access occasion is selected, on the basis of the preamble information, from among random access occasions corresponding to a second synchronization block, and the signal reception quality of the first synchronization block and the signal reception quality of the second synchronization block are both greater than or equal to a first threshold. A terminal apparatus sends a first message on random access occasions corresponding to a plurality of synchronization blocks, so that there are many opportunities for a network apparatus to receive the first message, thereby further improving the success rate of the terminal apparatus accessing the network apparatus, and reducing the time for the terminal apparatus to access the network apparatus.

Description

A communication method and apparatus

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411850587.5, filed on December 13, 2024, entitled "A Communication Method and Apparatus", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of communication technology, and in particular to a communication method and apparatus. Background Technology

[0004] Compared to traditional terrestrial networks (such as 4G or 5G terrestrial communication systems), non-terrestrial networks (NTNs) offer wider coverage, faster speeds, and lower costs. Especially in areas where terrestrial networks cannot be directly deployed, such as oceans, deserts, and the air, they can serve as a supplement or extension to terrestrial networks. By utilizing high, medium, and low Earth orbit satellites, they can achieve wide-area seamless coverage or even global coverage, providing seamless communication services to users worldwide and effectively solving internet access problems in areas lacking communication infrastructure.

[0005] Satellite communication, as a typical scenario of NTN (Network Telecommunication), features long communication distance, large coverage area, and flexible networking. It can provide services for both fixed terminal devices and various mobile terminal devices. When satellite communication is introduced into traditional communication systems (such as 5G communication systems), base stations or parts of their functions are deployed on satellites. This not only provides seamless coverage for terminal devices but also avoids the impact of natural disasters and ensures the reliability of the communication system.

[0006] However, in satellite communication scenarios, the period for satellite synchronization signal transmission (such as the synchronization signal and PBCH block, SSB) is relatively long (e.g., 640ms). This means that if a ground terminal fails to send message 1 (Msg1) during random access at the SSB corresponding to a random access opportunity where the signal reception quality is above a threshold, it needs to wait for one SSB cycle to retransmit message 1 at the corresponding random access opportunity. This results in a significant time consumption for the ground terminal to access the satellite. Therefore, further research is needed to reduce the time required for ground terminal devices to access satellites in satellite communication scenarios. Summary of the Invention

[0007] This application provides a communication method and apparatus to reduce the time required for ground terminal devices to access satellites in satellite communication scenarios.

[0008] Firstly, this application provides a communication method that can be executed by a terminal device. The terminal device can be a terminal equipment, or a component within the terminal equipment, such as a communication module, circuits or chips responsible for communication functions (e.g., modem chips, also known as baseband chips, or system-on-chip (SoC) chips containing modem cores or system-in-package (SIP) chips), chip systems, or processors, etc.), or logic modules or software capable of implementing all or part of the terminal equipment's functions. The method may include the following steps: the terminal device acquires a first message, and then the terminal device may send the first message at multiple random access times. The first message may include preamble information, and the multiple random access times may include a first random access time and a second random access time. The first random access time is selected from the random access time corresponding to the first synchronization block based on the preamble information, and the second random access time is selected from the random access time corresponding to the second synchronization block based on the preamble information. The reception time of the first synchronization block is earlier than the reception time of the second synchronization block, and the signal reception quality of both the first synchronization block and the second synchronization block is greater than or equal to a first threshold.

[0009] In this method, the terminal device can send the first message at random access times corresponding to multiple synchronization blocks. This increases the chances for the network device (e.g., a satellite) to receive the first message, improving the probability of the network device receiving the first message and thus increasing the success rate of the terminal device accessing the network device. Furthermore, compared to the excessively long random access process caused by the extended SSB period in satellite communication scenarios, this method, by sending the first message multiple times, increases the chances for the network device to receive the first message, giving the terminal device more opportunities to access the network device and increasing the success rate of the terminal device accessing the network device. This reduces the time (or access time) for the terminal device to access the network device. For example, in satellite communication scenarios, it reduces the time for ground terminal devices to access the satellite and improves the success rate of ground terminal devices accessing the satellite. In addition, where existing random access protocols do not support (or allow) parallel random access, this method, by having the terminal device send the first message at random access times corresponding to multiple synchronization blocks, enables multiple random access processes (or random access procedures) to be performed in parallel, helping to speed up the terminal device's access to the network device and thus reducing the time for the terminal device to access the network device.

[0010] In one possible implementation, the terminal device sends a first message at multiple random access points, including:

[0011] The terminal device uses a first transmit power to transmit a first message at a first random access opportunity; wherein, the first transmit power is related to the maximum transmit power of the terminal device and the first target receive power; the first target receive power is related to one or more of the following: initial target receive power, power offset related to the preamble format, first power ramp-up number, or power ramp-up step size;

[0012] The terminal device uses a second transmit power to transmit a first message at a second random access opportunity; wherein the second transmit power is related to the maximum transmit power of the terminal device and the second target receive power; the second target receive power is related to one or more of the following: initial target receive power, power offset related to the preamble format, second power ramp number, or power ramp step size.

[0013] In the above implementation, the terminal device can send the first message at multiple random access times with corresponding transmission power, which helps to realize multiple random access processes in parallel, helps to speed up the terminal device's access to the network device, and thus reduces the time for the terminal device to access the network device.

[0014] In one possible implementation, when the first synchronization block and the second synchronization block are in the same cycle, the number of first power ramps is the same as the number of second power ramps.

[0015] Compared to existing protocols that determine power ramping (i.e., preamble_Power_Ramping_Counter++) for the current first message transmission based on whether the synchronization block (e.g., SSB) used in the current first message transmission is the same as the synchronization block used in the previous (or earlier) first message transmission, the above implementation does not perform power ramping (i.e., preamble_Power_Ramping_Counter remains unchanged) when the synchronization block (e.g., SSB) used in the current first message transmission is in the same cycle as the synchronization block used in the previous first message transmission. In other words, no power ramping is performed for the current first message transmission compared to the previous first message transmission. This implementation allows the first message to be transmitted within a single cycle using the same number of power ramps but different synchronization blocks, which helps improve the success rate of the first message being received by the network device.

[0016] In one possible implementation, when the first synchronization block and the second synchronization block are in different cycles, the second power ramp number is equal to the sum of the first power ramp number and M, where M is a preset positive integer.

[0017] Compared to existing protocols that determine that the current first message transmission does not perform power ramp-up (i.e., preamble_Power_Ramping_Counter remains unchanged) because the synchronization block (e.g., SSB) used in the current first message transmission is different from the synchronization block used in the previous (or earlier) first message transmission, the above implementation performs power ramp-up (i.e., preamble_Power_Ramping_Counter++) even when the synchronization block (e.g., SSB) used in the current first message transmission is in a different period than the synchronization block used in the previous first message transmission. In other words, the current first message transmission performs power ramp-up relative to the previous first message transmission. This implementation allows for the transmission of the first message in different periods by increasing the number of power ramp-ups, which helps improve the success rate of the first message being received by the network device.

[0018] In one possible implementation, the method further includes:

[0019] The terminal device detects the response message corresponding to the first message within N time windows; wherein, the N time windows are one or more of the time windows corresponding to multiple random access opportunities.

[0020] In the above implementation, the terminal device can detect N time windows in parallel, which gives the terminal device more opportunities to receive the response message corresponding to the first message. This helps to increase the success rate of the terminal device receiving the response message corresponding to the first message, thereby improving the success rate of the terminal device accessing the network device and speeding up the terminal device access to the network device, enabling the terminal device to access the network device faster.

[0021] In one possible implementation, the method further includes:

[0022] If the number of time windows corresponding to multiple random access opportunities is greater than the number of time windows supported by the terminal device, the terminal device can select N time windows that satisfy the first condition from the time windows corresponding to multiple random access opportunities.

[0023] In the above implementation, considering the limited detection time window capability of the terminal device, the terminal device can timely and effectively filter N time windows according to the first condition, thereby meeting the terminal device's detection time window capability requirements and improving the success rate of the terminal device accessing the network device.

[0024] In one possible implementation, the first condition may include:

[0025] The signal reception quality of the synchronization block corresponding to the time window is greater than the second threshold, where the second threshold is greater than the first threshold; or,

[0026] The synchronization block corresponding to the time window belongs to the first P of the signal reception quality sorting table. The signal reception quality sorting table can include multiple synchronization blocks sorted from high to low signal reception quality, where P is a positive integer greater than or equal to N.

[0027] The above implementation method enables the terminal device to use a synchronization block with high signal reception quality to perform multiple random accesses, which helps the terminal device to have more opportunities to access the network device, thereby improving the success rate of the terminal device accessing the network device and speeding up the access speed of the terminal device to the network device.

[0028] In one possible implementation, the method further includes:

[0029] If the first response message corresponding to the first message detected within the first time window of N time windows meets the second condition, the terminal device may stop sending the first message and / or stop detecting the response message corresponding to the first message.

[0030] The second condition may include one or more of the following:

[0031] The information in the preamble included in the first response message is the same as the information in the preamble included in the first message.

[0032] The first response message includes a random access radio network temporary identity (RA-RNTI) that is identical to the RA-RNTI stored on the terminal device.

[0033] The above implementation allows the terminal device to successfully parse (or receive) the response message of one of N concurrent random access procedures. In this case, the terminal device can terminate (or stop) other ongoing time window detections, and / or prohibit (or stop) the transmission of subsequent first messages, thus saving power consumption. Successful parsing or reception means that the preamble information in a detected response message is the same as the preamble information in the corresponding first message, and / or that the RA-RNTI in the response message is the same as the RA-RNTI stored locally by the terminal device or determined by the terminal device. In other words, if the preamble information in a detected response message is the same as the preamble information in the corresponding first message, and / or the RA-RNTI in the response message is the same as the RA-RNTI stored locally by the terminal device or determined by the terminal device, then it can be determined that the response message has been successfully parsed or received by the terminal device.

[0034] In one possible implementation, the terminal device sends a first message at multiple random access points, including:

[0035] The terminal device sends the first message at the first random access opportunity;

[0036] The terminal device may send the first message at the second random access time before detecting the response message corresponding to the first message within the time window corresponding to the first random access time; or,

[0037] The terminal device can send the first message at the second random access time before the time window corresponding to the first random access time ends.

[0038] Compared to existing random access schemes that can only resend (or retransmit) the first message after the failure to receive the response message corresponding to the previously sent first message, or after the end of the time window corresponding to the previously sent first message, the above implementation method can enable the terminal device to resend the first message before the failure to receive the response message corresponding to the previously sent first message, or before the end of the time window corresponding to the previously sent first message, thereby enabling multiple transmissions of the first message and parallel execution of multiple random access processes.

[0039] Secondly, this application provides a communication method that can be executed by a network device. The network device can be a network equipment or a component within a network equipment, such as a communication module, processor, chip, chip system, or circuit applicable to a first access network device (e.g., a satellite), or a logic module or software capable of implementing all or part of the functions of the first access network device. The method may include the following steps: the network device receives a first message at multiple random access times, wherein the first message may include preamble information, the multiple random access times may include a first random access time and a second random access time, the first random access time is selected from the random access time corresponding to a first synchronization block based on the preamble information, the second random access time is selected from the random access time corresponding to a second synchronization block based on the preamble information, the reception time of the first synchronization block is earlier than the reception time of the second synchronization block, and the signal reception quality of both the first and second synchronization blocks is greater than or equal to a first threshold.

[0040] In one possible implementation, the network device receives the first message at multiple random access times, including:

[0041] The network device receives a first message at a first random access opportunity, and the first message received at the first random access opportunity is transmitted using a first transmit power; wherein, the first transmit power is related to the maximum transmit power of the terminal device and the first target receive power; the first target receive power is related to one or more of the following: initial target receive power, power offset related to the preamble format, first power ramp-up number, or power ramp-up step size;

[0042] The network device receives the first message at a second random access opportunity, and the first message received at the second random access opportunity is transmitted using a second transmit power; wherein, the second transmit power is related to the maximum transmit power of the terminal device and the second target receive power; the second target receive power is related to one or more of the following: initial target receive power, power offset related to the preamble format, second power ramp number, or power ramp step size.

[0043] In one possible implementation, when the first synchronization block and the second synchronization block are in the same cycle, the number of first power ramps is the same as the number of second power ramps.

[0044] In one possible implementation, when the first synchronization block and the second synchronization block are in different cycles, the second power ramp number is equal to the sum of the first power ramp number and M, where M is a preset positive integer.

[0045] In one possible implementation, the network device receives the first message at multiple random access times, including:

[0046] The network device receives the first message at the first random access opportunity;

[0047] The network device may receive the first message at the second random access time before sending the response message corresponding to the first message within the time window corresponding to the first random access time; or,

[0048] The network device can receive the first message at the second random access time before the time window corresponding to the first random access time ends.

[0049] The technical effects achievable by the second aspect or any implementation thereof are described in reference to the technical effects achievable by the first aspect or its corresponding implementation method, and will not be repeated here.

[0050] Thirdly, this application provides a communication device including units or means for performing the various steps of any of the implementation methods in the first aspect described above.

[0051] For example, the communication device can be a terminal device, such as a terminal equipment or a module within a terminal equipment (e.g., a processor, processing unit, chip system, circuit, or chip). The communication device has the functionality to implement the method in any of the possible implementations of the first aspect described above. This functionality can be implemented in hardware or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the aforementioned functionality.

[0052] Fourthly, this application provides a communication apparatus, including units or means for performing the various steps of any of the implementation methods in the second aspect described above.

[0053] For example, the communication device can be a network device, such as a network equipment or a module within a network equipment (e.g., a processor, processing unit, chip system, circuit, or chip). The communication device has the functionality to implement the method in any of the possible implementations of the second aspect described above. This functionality can be implemented in hardware or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the aforementioned functionality.

[0054] Fifthly, this application provides a communication device that has the functions involved in the first to second aspects described above. For example, the communication device includes modules, units, or means that perform the operations involved in the first to second aspects described above. The functions, units, or means can be implemented by software, or by hardware, or by hardware executing corresponding software.

[0055] In one possible implementation, the communication device includes a transceiver unit (or communication module, transceiver module, or communication unit for sending and receiving data). Optionally, the communication device may further include a processing unit (or processing module), wherein the transceiver unit can be used to send and receive signals to enable communication between the communication device and other devices, for example, the transceiver unit can be used to send data to other communication devices; the processing unit can be used to perform some internal operations of the communication device. The functions performed by the transceiver unit and the processing unit may correspond to the operations involved in the first to second aspects described above.

[0056] In one possible implementation, the communication device includes a processor that can be coupled to a memory. The memory can store necessary computer programs or instructions for implementing the functions described in the first to second aspects above. The processor can execute the computer programs or instructions stored in the memory, causing the communication device to implement the methods in any possible implementation of any of the first to second aspects above when the computer programs or instructions are executed.

[0057] In one possible implementation, the communication device includes a processor and a memory, the memory of which may store necessary computer programs or instructions for implementing the functions involved in the first to second aspects described above. The processor may execute the computer programs or instructions stored in the memory, and when the computer programs or instructions are executed, cause the communication device to implement the methods in any possible implementation of any of the first to second aspects described above.

[0058] In one possible implementation, the communication device includes a processor and an interface circuit (or communication interface), wherein the processor is used to communicate with other devices through the interface circuit and to execute the methods in any possible implementation of any of the first to second aspects described above. The interface circuit is used to enable communication between the communication device and other devices, for example, to receive signals from other communication devices and transmit them to the processor, or to send signals from the processor of the communication device to other communication devices, such as the transmission or reception of data and / or signals. Exemplarily, the communication interface may be a transceiver, circuit, bus, module, or other type of communication interface.

[0059] It is understood that, in the fifth aspect mentioned above, 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. Furthermore, there can be one or more processors, and one or more memories. The memory can be integrated with the processor, or the memory and processor can be separately configured. In specific implementations, the memory can be integrated with the processor on the same chip, or it can be configured on different chips. This application does not limit the type of memory or the configuration of the memory and processor.

[0060] Sixthly, this application also provides a communication system, including a terminal device for implementing the first aspect or any implementation method of the first aspect, and a network device for implementing the second aspect or any implementation method of the second aspect. The relevant functional implementations of the terminal device or network device can be found in the descriptions mentioned in the first or second aspects above, and will not be repeated here.

[0061] For example, the number of terminal devices or network devices can be one or more.

[0062] In a seventh aspect, this application provides a computer program product comprising a computer program or instructions that, when executed on a communication device (or computer), cause the communication device (or computer) to perform the method in any possible implementation of any of the first to second aspects described above.

[0063] Eighthly, this application provides a computer-readable storage medium storing a computer program or instructions that, when executed by a communication device (or computer), cause the communication device (or computer) to perform the method in any possible implementation of any of the first to second aspects described above.

[0064] Ninthly, this application provides a chip that may include a processor and may also include a memory (or the chip may be coupled to the memory), the chip executing program instructions in the memory to cause the chip to perform the methods in any possible implementation of any of the first to second aspects described above. Here, "coupling" means that two components are directly or indirectly connected to each other, such as coupling can refer to an electrical connection between two components.

[0065] In a tenth aspect, this application also provides a chip system including a processor for supporting a computer device in implementing any possible implementation of the methods in any of the first to second aspects described above. In one possible implementation, the chip system further includes a memory for storing programs and data necessary for the computer device. The chip system may be composed of chips or may include chips and other discrete devices.

[0066] Based on the implementation methods provided in the above aspects, this application can be further combined to provide more implementation methods. Attached Figure Description

[0067] Figure 1 illustrates a schematic diagram of an embodiment of this application for transmitting an SSB;

[0068] Figure 2 illustrates an exemplary architectural diagram of a terrestrial communication system provided in an embodiment of this application;

[0069] Figure 3 illustrates a possible satellite communication system architecture provided in an embodiment of this application.

[0070] Figure 4 illustrates, by way of example, a conventional random access protocol provided in an embodiment of this application that does not allow parallel random access;

[0071] Figure 5 illustrates a flowchart of a communication method provided in an embodiment of this application;

[0072] Figure 6a illustrates a schematic diagram of a parallel detection RAR window provided in an embodiment of this application;

[0073] Figure 6b illustrates an exemplary schematic diagram of another parallel detection RAR window provided in an embodiment of this application;

[0074] Figure 7 illustrates a schematic diagram of the structure of a communication device provided in an embodiment of this application;

[0075] Figure 8 illustrates a schematic diagram of another communication device provided in an embodiment of this application. Detailed Implementation

[0076] Before introducing the technical solutions provided in this application, some of the terms used in this application will be explained in order to facilitate understanding by those skilled in the art.

[0077] (1) SSB (or Synchronization Signal Block): The SSB consists of three parts: primary synchronization signals (PSS), secondary synchronization signals (SSS), and PBCH. Both PSS and SSS are synchronization signals. PSS can be used to transmit the cell number, and SSS can be used to transmit the cell group number. The cell number and cell group number together determine multiple physical cell identities (PCIs) in the communication system. Once the terminal device successfully finds the PSS and SSS, it knows the PCI corresponding to the SSB. PBCH can be used by the terminal device to obtain information about the access cell. For example, PBCH can be used to indicate the physical downlink shared channel (PDSCH) carrying system information block 1 (SIB1). SIB1 can be used to configure random access resources. The terminal device can access the network according to the random access resources. Optionally, SIB1 can also be used to carry paging configurations, such as paging configurations used to configure parameters related to receiving paging messages.

[0078] (2) SSB Transmission: Network devices can transmit different SSBs at different times using different beams. Each beam can be indicated by an SSB, for example, by the index of the SSB transmitted on that beam. Since different beams cover different areas, the beam in "network devices can transmit different SSBs at different times using different beams" can be replaced with an area.

[0079] For example, a network device can send SSBs at certain intervals; within each interval (or SSB period), the network device can send SSBs for a portion of the interval's duration. For instance, as shown in Figure 1, the network device sends SSBs at 20 milliseconds (ms); within each interval, the network device can send 4 SSBs using 4 beams within 5 ms.

[0080] It should be understood that Figure 1 is merely an example, and the period for sending SSBs can also be other values, such as 10ms, 40ms, 80ms, 160ms, 320ms, or 640ms. The duration and number of SSBs sent by the network device within each period can also be other values, and this application does not limit them.

[0081] (3) Beam: This refers to the main lobe of the directional array pattern. Network devices (such as satellites, which can also be called high-altitude platforms, high-altitude aircraft, or satellite base stations) can adjust the antenna weights so that the network device's beam can point in different directions, resulting in different coverage areas (or coverage regions or geographical coverage ranges). In this application, the beam coverage range refers to the beam's coverage area on the ground. For example, the beam coverage range can include at least one location point. As the satellite moves and the weights are adjusted, the beam coverage range will also change.

[0082] It is understandable that a beam can be a wide beam, a narrow beam, or other types of beams. The technology used to form the beam can be beamforming technology or other technologies. Specifically, beamforming technology can be digital beamforming technology, analog beamforming technology, or hybrid digital / analog beamforming technology, etc. Beams can be associated with resources. For example, during beam measurement, network devices measure different beams using different resources. The terminal device reports the measured resource quality, and the network device knows the quality of the corresponding beam. In data transmission, beam information is also indicated through its corresponding resources. For example, network devices use the transmission configuration indicator (TCI) field in downlink control information (DCI) to indicate the PDSCH beam information of the terminal device.

[0083] For example, network devices can generate different beams pointing in different transmission directions. In downlink data transmission, when a network device sends data to a terminal device using a specific beam, it needs to inform the terminal device of the transmit beam information so that the terminal device can use the corresponding receive beam to receive the data sent by the network device.

[0084] Optionally, in some embodiments, multiple beams having the same or similar communication characteristics can be considered as a single beam. A beam may include one or more antenna ports for transmitting data channels, control channels, and probe signals, etc. One or more antenna ports forming a beam can also be considered as a set of antenna ports.

[0085] (4) Random Access: In 5G communication systems or other communication systems, this is an information exchange mechanism (or process) used by devices not connected to the network (such as terminal devices) to establish a connection with the network. Since the random access process is carried by the random access channel (RACH), RA and RACH are often used interchangeably in protocols and colloquial speech to refer to random access. Random access is divided into contention-based random access and non-contention-based random access. Contention-based random access typically consists of four steps, each corresponding to a message: message 1, message 2, message 3, and message 4, each carrying different signaling or information. Non-contention-based random access only has the first two steps. Furthermore, to reduce the access time of the four-step contention-based random access, there is a two-step random access. In two-step random access, there are two messages, A and B. Message A includes a preamble (or preamble code or random access preamble) and the first data information (e.g., similar to messages 1 and 3 in four-step random access). Message B includes contention resolution and uplink scheduling (e.g., similar to messages 2 and 4 in four-step random access).

[0086] (5) RACH occasion (RO): Also known as RACH resource or RACH chance, it refers to the time and frequency resources used to carry one or more random access preambles. Logically, a random access occasion is used to carry information / signals of the physical random access channel (PRACH). Sometimes it is also equivalently referred to as physical random access occasion (RO) or physical random access resource (PRACH resource).

[0087] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0088] The following describes the communication system architecture to which the communication method provided in this application is applicable. It should be noted that this description is for the convenience of those skilled in the art and does not constitute a limitation on the scope of protection claimed in this application.

[0089] The communication scheme provided in this application can be applied to various communication systems, such as: Long Term Evolution (LTE) systems, LTE Frequency Division Duplex (FDD) systems, LTE Time Division Duplex (TDD) systems, sidelink (SL) communication systems, Universal Mobile Telecommunication System (UMTS), Worldwide Interoperability for Microwave Access (WiMAX) communication systems, 5th Generation (5G) mobile communication systems or new radio access technology (NR), satellite communication systems, etc. Among them, 5G mobile communication systems can include non-standalone (NSA) and / or standalone (SA) networks. The technical solution provided in this application can also be applied to future evolving communication systems. Satellite communication systems can be satellite communication systems integrated with 4G, 5G mobile communication systems, or future communication systems, such as non-terrestrial networks (NTNs), etc. NTN communication systems can be, for example, satellite communication systems, or include unmanned aerial vehicles, high altitude platform stations (HAPS), and other aerial access network equipment; this application does not limit the scope of such systems.

[0090] In a communication system, one network element can send signals to or receive signals from another network element. These signals can include information, signaling, or data. The term "network element" can also be replaced with entities, network entities, devices, communication equipment, communication modules, nodes, communication nodes, etc.

[0091] For example, a terrestrial communication system may include at least one terminal device and at least one network device. The network device may send downlink signals to the terminal device, and / or the terminal device may send uplink signals to the network device. Furthermore, it is understood that if the communication system includes multiple terminal devices, these terminal devices may also exchange signals; that is, both the transmitting network element and the receiving network element can be terminal devices.

[0092] Figure 2 illustrates an exemplary architecture diagram of a terrestrial communication system applicable to an embodiment of this application. The communication system 200 may include network device 210 and terminal devices 201 to 206. It should be understood that the communication system 200 may include more or fewer network devices or terminal devices. Network devices or terminal devices may be hardware, functionally defined software, or a combination of both. Furthermore, terminal devices 204 to 206 may also form a communication system; for example, terminal device 205 may send downlink data to terminal device 104 or terminal device 206. Communication between network devices and terminal devices can occur through other devices or network elements. Network device 210 may send downlink data to terminal devices 201 to 206 and may also receive uplink data sent by terminal devices 201 to 206. Conversely, terminal devices 201 to 206 may also send uplink data to network device 210 and may also receive downlink data sent by network device 210.

[0093] Network device 210 is a node in the radio access network (RAN), also known as a base station, RAN node (or device), RAN entity, access network device, or access node, etc. Currently, some examples of access network devices include: evolved NodeB (eNodeB), access point (AP), access point (AP) in wireless fidelity (WIFI) systems, wireless relay node, wireless backhaul node, transmission point (TP), next generation node B (gNB) in 5G networks, transmitting point (TP), transmission reception point (TRP), home base station (e.g., home evolved NodeB, or home Node B, HNB), macro base station, micro base station (also called small station), relay station, satellite station, base band unit (BBU), and other network devices in communication systems evolving after 5G. Network device 210 can also be other devices with network device functions, such as gNB, TRP, or TP in a 5G system, or one or a group of antenna panels (including multiple antenna panels) of a base station in a 5G system. Furthermore, network device 210 can also be a device that performs base station functions in device-to-device (D2D), vehicle-to-everything (V2X), Internet of Things (IoT), machine-to-machine (M2M) communication, or other communication systems. It can also include CU and DU in cloud radio access network (C-RAN) systems, and network devices in non-terrestrial network (NTN) communication systems, and can be deployed on high-altitude platforms or satellites. This application embodiment does not specifically limit this. For example, in a satellite communication system, the network device can be a satellite or a base station device mounted on a satellite.

[0094] For example, in some possible network architectures, network devices can be CUs, DUs, CUs (control plane, CP), CUs (user plane, UP), or radio units (RUs), etc. CUs and DUs can be configured separately or included in the same network element, such as a baseband unit (BBU). RUs can be included in radio equipment or radio units, such as remote radio units (RRUs), active antenna units (AAUs), or remote radio heads (RRHs). In this network architecture, signaling generated by the CU can be sent to the terminal device via the DU, or signaling generated by the terminal device can be sent to the CU via the DU. The DU can directly pass the signaling through protocol layer encapsulation without parsing it to the terminal device or CU. In this network architecture, the CU is classified as a network device on the radio access network side; alternatively, the CU can also be classified as a network device on the core network side, and this application does not impose any limitations on this. For example, the functions of the PDCP layer and above are located in the CU, while the functions of the protocol layers below the PDCP layer (such as the RLC layer and MAC layer) are located in the DU. It's important to understand that the above division of the processing functions of the CU and DU according to protocol layers is just one example; other methods can also be used. For instance, the functions of the protocol layers above the RLC layer could be located in the CU, and the functions of the protocol layers below the RLC layer could be located in the DU. Alternatively, the CU or DU could be divided into those with functions from more protocol layers, or even those with partial processing functions from protocol layers.

[0095] It is understood that CU (or CU-CP and CU-UP), DU, or RU may have different names in different systems, but those skilled in the art will understand their meaning. For example, in an ORAN system, CU can also be called O-CU (open CU), DU can also be called O-DU, CU-CP can also be called O-CU-CP, CU-UP can also be called O-CU-UP, and RU can also be called O-RU. For ease of description, this application uses CU, CU-CP, CU-UP, DU, and RU as examples. Any of the units among CU (or CU-CP, CU-UP), DU, and RU in this application can be implemented through software modules, hardware modules, or a combination of software modules and hardware modules.

[0096] Optionally, if the network equipment adopts a CU-DU separation architecture, this CU-DU separation architecture can also be called a distributed deployment architecture, or it can adopt a CU-DU-RU separation architecture. For example, the network equipment can logically include one CU and one or more DUs. Each DU can be connected to the CU through an F1 interface, and information exchange between different DUs can be completed based on the forwarding of the CU. The CU and DU can be physically set together or physically separated, without limitation. The CU can support the functions of RRC layer protocols, PDCP protocol, and SDAP protocol; the DU can support RLC layer protocols, MAC layer protocols, and some or all PHY layer functions. For specific descriptions of the above protocol layers, please refer to the relevant 3GPP technical specifications. As another example, the access network equipment can logically include CU, DU, and RU. The CU and DU can be physically set together or physically separated, without limitation. The CU can support the functions of RRC layer protocols, PDCP protocol, and SDAP protocol; the DU can support the functions of RLC layer protocols and MAC layer protocols, and can also support some PHY layer protocols; the RU can support some or all PHY layer functions. For example, the DU is mainly responsible for higher-level protocol functions such as data encryption and integrity protection, while the RU is mainly responsible for transmitting and receiving radio frequency signals. In the CU-DU-RU separation architecture, the interface between the DU and RU can be called the fronthaul, the interface between the CU and DU can be called the midhaul, and the interface between the CU and the core network can be called the backhaul.

[0097] Terminal devices 201 to 206 are devices that provide voice or data connectivity to users. They can also be Internet of Things (IoT) devices, and are also referred to as terminals, user equipment (UE), access terminal equipment, vehicle-mounted terminals, industrial control terminals, UE units, UE stations, mobile stations, mobile stations (MS), mobile terminals (MT), remote stations, remote terminal equipment, mobile devices, UE terminal equipment, terminal equipment, wireless communication equipment, UE agents, or UE devices, etc. For example, terminal devices 201 to 206 include handheld devices and vehicle-mounted devices with wireless connectivity.Currently, terminal devices 201 to 206 can be: mobile phones, tablets, customer-premises equipment (CPE), subscriber units, satellite phones, cellular phones, smartphones, cordless phones, session initiation protocol (SIP) phones, wireless local loop (WLL) stations, wireless data cards, personal digital assistant (PDA) computers, wireless modems, handsets, laptop computers, computers with wireless transceiver capabilities, virtual reality (VR) terminal devices, augmented reality (AR) terminal devices, head-mounted displays (HMDs), wireless terminals in industrial control, mobile internet devices (MIDs), vehicle-mounted terminal devices (e.g., cars, bicycles, electric vehicles, airplanes, ships, trains, high-speed trains, etc.), and self-driving cars. Wireless terminals in various fields, including driving, remote medical care, smart grids, transportation safety, smart cities, smart homes, wearable devices (such as smartwatches, smart bracelets, pedometers, etc.), vehicles, drones, helicopters, airplanes, factory machinery / equipment, machine-type communication (MTC) terminals, ships, and robots. Terminal devices 201 to 206 can also be other devices with terminal functions; for example, terminal devices 201 to 206 can also function as terminals in D2D communication.

[0098] Based on the description of the terrestrial communication system architecture shown in Figure 2, this application embodiment can be illustrated by using a non-terrestrial network (NTN) communication system. NTN includes nodes such as satellite networks, high-altitude platforms, and unmanned aerial vehicles (UAVs), and has significant advantages such as global coverage, long-distance transmission, flexible networking, convenient deployment, and no geographical limitations. It has been widely used in various fields such as maritime communication, positioning and navigation, disaster relief, scientific experiments, video broadcasting, and Earth observation. Terrestrial communication systems and NTN communication systems such as satellite networks integrate with each other, complementing each other's strengths and weaknesses, to jointly form a globally seamless, integrated sea, land, air, space, and ground communication network, meeting the ubiquitous and diverse service needs of users. In this application embodiment, NTN communication is exemplified by satellite communication, or in other words, the NTN communication system is exemplified by a satellite communication system. Figure 3 is a schematic diagram of a possible satellite communication system architecture applicable to this application embodiment. As shown in Figure 3, this satellite communication system architecture may include at least one terminal device (e.g., terminal device 1, terminal device 2, etc.), at least one satellite (e.g., satellite 1, satellite 2, etc.) (or a base station deployed on the satellite, such as a 5G base station), a ground station, a core network (CN) (e.g., a 5G core network), and a data network (DN). The terminal device and the satellite (or the base station deployed on the satellite) can communicate via an air interface (which can be any type of air interface, such as 5G New Radio). For example, taking terminal device 1 as an example, terminal device 1 can access satellite 1 via a 5G New Radio interface. There are wireless links (e.g., the Xn interface) between satellites (or base stations deployed on the satellite), which can be used for signaling interaction and user data transmission between base stations. For example, satellites (or base stations deployed on the satellite) can communicate via the Xn interface. The satellite and the ground station can communicate via the NG interface. The ground station can connect to the core network via the NG interface, which can be wired or wireless. The core network and the data network can communicate via the N6 interface. Satellites can typically form multiple beams, each beam similar to a cell / sector in a terrestrial mobile communication system (such as LTE / NR).

[0099] The following is a brief introduction to the equipment and interfaces included in the satellite communication system architecture.

[0100] (1) Base station: It is mainly used to provide wireless access services, allocate wireless resources to access terminal equipment, and provide reliable wireless transmission protocols and data encryption protocols. For example, a base station can be regarded as a network device 210 included in the communication system 200, or a device (such as a chip or chip system) used to implement the functions of the network device 210.

[0101] (2) Core Network: Primarily used to provide functions such as user access control, mobility management, session management, user security authentication, and billing. The core network consists of multiple functional units, which can be divided into control plane network elements (or control plane functional units) and user plane network elements (or user plane processing units). User plane network elements are responsible for the transmission of service data; for example, user plane network elements may include, but are not limited to, user plane function (UPF) network elements. Control plane network elements are responsible for the management of the mobile network; for example, control plane network elements may include, but are not limited to, access and mobility management function (AMF) network elements and session management function (SMF) network elements. AMF network elements are responsible for user access management, security authentication, and mobility management. SMF network elements are responsible for terminal device session management (including session establishment, modification, and release), UPF network element selection and reselection, terminal device Internet Protocol (IP) address allocation, Quality of Service (QoS) control, and selection of UPF network elements providing packet forwarding functions. UPF is used to manage user plane data transmission, traffic statistics, and other functions.

[0102] (3) Data Network: A data network that provides business services (such as data and / or voice services) to users. Generally, the client is located on the terminal device, and the server is located on the data network. The data network can be a private network, such as a local area network, or an external network not controlled by the operator, such as the Internet, or a dedicated network jointly deployed by the operator, such as a network that provides IP multimedia core network subsystem (IMS) services.

[0103] (4) Ground station: mainly responsible for forwarding signaling and service data between satellite and core network.

[0104] (5) 5G New Radio: refers to the wireless link between the terminal device and the satellite.

[0105] (6) Xn interface: This refers to the interface between satellites (or base stations deployed on satellites), mainly used for signaling interaction such as handover.

[0106] (7) NG interface: This refers to the interface between the satellite and the core network. It mainly exchanges non-access stratum (NAS) signaling of the core network and user service data.

[0107] In this application embodiment, network devices in a terrestrial communication system and satellites in an NTN communication system can be uniformly considered as network devices. The apparatus for implementing the functions of a network device can be a network device itself; it can also be an apparatus capable of supporting the network device in implementing that function, such as a chip system, which can be installed within the network device. The following description of the technical solutions provided in this application embodiment uses a satellite as an example to illustrate the technical solutions provided in this application embodiment. It is understood that when the method provided in this application embodiment is applied to a terrestrial communication system, the actions performed by the satellite can be applied to the base station or network device for execution.

[0108] In this application embodiment, the device for implementing the functions of the terminal device can be the terminal device itself; it can also be a device capable of supporting the terminal device in implementing the functions, such as a chip system, hardware circuit, software module, or hardware circuit plus software module. This device can be installed in the terminal device or used in conjunction with the terminal device. In this application embodiment, the chip system can be composed of chips or can include chips and other discrete devices. The technical solutions provided in this application embodiment are described using the example of a terminal device as the device for implementing the functions of the terminal device.

[0109] It should be noted that the communication system and business scenarios described in the embodiments of this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. As those skilled in the art will know, with the evolution of network architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0110] In satellite communication scenarios, ground terminal equipment can use either a random access channel (RACH) procedure or a random access channel-less (RACH-less) procedure to access the satellite (or network equipment deployed on the satellite) to enable communication (such as data transmission or signaling interaction) between the ground terminal equipment and the satellite (or network equipment deployed on the satellite). Specifically, during the RACH or RACH-less procedure, the ground terminal equipment sends message 1 to the satellite (or network equipment deployed on the satellite).

[0111] However, according to the random access protocol in existing satellite communication scenarios, if the SSB index corresponding to the RO used by the ground terminal equipment in two consecutive transmissions of message 1 (or message A or the first message) is the same, then the transmission power of the later message 1 is greater than that of the earlier message 1. If the SSB index corresponding to the RO used by the ground terminal equipment in two consecutive transmissions of message 1 is different, then the transmission power of the two consecutive transmissions of message 1 is the same. The SSB index corresponding to the RO used in two consecutive transmissions of message 1 corresponds to different SSB periods. For example, please refer to Figure 4, which uses an SSB period of 640ms, with 256 SSBs transmitted within one SSB period, and the ground terminal equipment being able to receive 4 SSBs (e.g., SSB#1, SSB#2, SSB#9, and SSB#10) within one SSB period. Within one SSB period, the 256 SSBs are divided into 32 groups for transmission, with 8 SSBs in each group, and the time interval between two adjacent groups (which can be understood as the transmission time interval) is 20ms. The ground terminal equipment can first receive SSB#1 and SSB#2, and after measuring SSB#1 and SSB#2, obtain the signal reception quality of SSB#1 and SSB#2. Assuming the signal reception quality of SSB#1 is greater than that of SSB#2, the ground terminal equipment uses SSB#1 for random access. That is, the ground terminal equipment can determine from at least one RO corresponding to SSB#1 which it will use to send message 1—either the RO corresponding to the preamble or the preamble index. Afterwards, the ground terminal equipment can receive SSB#9 and SSB#10, and after measuring SSB#9 and SSB#10, obtain their signal reception quality. Because existing random access protocols do not support (or do not allow) parallel random access, even if the signal reception quality of one or more SSBs in SSB#9 and SSB#10 is greater than that of SSB#1, or if the signal reception quality of one or more SSBs in SSB#9 and SSB#10 exceeds a quality threshold, the ground terminal equipment cannot use one or more SSBs in SSB#9 and SSB#10 for random access, thus wasting access opportunities. Specifically, as shown in Figure 4, since the random access response (RAR) window corresponding to the previous message 1 has not yet timed out (or ended), the ground terminal equipment cannot use one or more SSBs in SSB#9 and SSB#10 to resend message 1 (or retransmit it).It is understandable that, since the time interval between the groups containing SSB#1 and SSB#2 and the groups containing SSB#9 and SSB#10 is 20ms, the ground terminal equipment does not know the measurement results of SSB#9 and SSB#10 when measuring SSB#1 and SSB#2. Therefore, even if the signal reception quality of one or more SSBs in SSB#9 and SSB#10 is greater than that of SSB#1, one or more SSBs in SSB#9 and SSB#10 can still be used for random access.

[0112] Furthermore, due to measurement errors, the ground terminal equipment has difficulty accurately selecting the SSB for transmitting message 1 based on the measurement results, thus preventing the transmission power of message 1 from increasing. Specifically, due to measurement errors, the ground terminal equipment might use SSB#1 in a previous transmission of message 1, and SSB#9 in a subsequent transmission, and so on, preventing the transmission power of message 1 from increasing and thus hindering effective satellite reception of message 1, resulting in a low success rate for message 1 reception. Specifically, the SSB#1 used in the previous transmission of message 1 belongs to the SSB#1 received in the previous SSB cycle, and the SSB#9 used in the subsequent transmission belongs to the SSB#9 received in the subsequent SSB cycle. Each SSB cycle includes both SSB#1 and SSB#9.

[0113] In view of this, this application provides a communication method to reduce the time for ground terminal equipment to access the satellite in satellite communication scenarios, and to improve the success rate of message 1 being received by the satellite.

[0114] The specific implementation of the communication method in the embodiments of this application will be described in detail below with reference to the accompanying drawings. It is understood that the following embodiments use a network device and a terminal device as examples to illustrate the execution of the interaction, but this application does not limit the execution of the interaction. For example, a network device can be a network equipment, or a component within a network equipment, such as a communication module, processor, chip, chip system, or circuit that can be applied to a first access network device. It can also be a logic module or software that can implement all or part of the functions of the first access network device. A terminal device can be a terminal equipment, or a component within a terminal equipment, such as a communication module, circuit or chip responsible for communication functions (e.g., a modem chip, also known as a baseband chip, or a system-on-a-chip (SoC) chip or system-in-package (SIP) chip containing a modem core), chip system, or processor that can be applied to a terminal equipment. It can also be a logic module or software that can implement all or part of the functions of the terminal equipment.

[0115] Figure 5 illustrates a flowchart of a communication method provided in an embodiment of this application. This method is applicable to the communication system architecture shown in Figure 2 or Figure 3. As shown in Figure 5, the method includes:

[0116] Step 501: The terminal device obtains the first message.

[0117] For example, the terminal device can determine (or generate) the first message. Then, the terminal device can retrieve the first message. Alternatively, the terminal device can retrieve the first message from another device.

[0118] Step 502: The terminal device sends a first message at multiple random access opportunities. Correspondingly, the network device receives the first message at multiple random access opportunities.

[0119] The first message may include preamble information. For example, the preamble information may include at least one of the following: the preamble itself, or the index of the preamble (or preamble index). Optionally, the first message may also be referred to as message 1 or message A, etc.

[0120] The first message can be carried through the physical random access channel (PRACH), and is typically used by the terminal device to initiate connection requests (or access requests), handover requests, synchronization requests, or scheduling requests to the network device.

[0121] For example, the preamble can be a sequence used to notify the network device of a random access request. After receiving the first message, the network device obtains the preamble or preamble index by detecting the first message and can estimate the transmission delay between the terminal device and the network device. Then, the network device can determine the timing advance (TA) based on the transmission delay between the terminal device and the network device. Optionally, the network device can assign a Random Access Radio Network Temporary Identifier (RA-RNTI) to the current random access, and can also assign a Temporary Cell Radio Network Temporary Identifier (TC-RNTI) to the randomly accessing terminal device, and can also determine the uplink grant (UL grant, uplink, UL) or permission for message 3 (Msg3).

[0122] For example, multiple random access opportunities may include a first random access opportunity (referred to as the first RO) and a second random access opportunity (referred to as the second RO). The first and second random access opportunities are described below.

[0123] (1) The first random access opportunity may be determined by the terminal device from at least one random access opportunity corresponding to the first synchronization block based on the preamble or preamble index.

[0124] The signal reception quality of the first synchronization block (or the first synchronization signal or the first synchronization signal block) is greater than or equal to the first threshold.

[0125] For example, parameters used to represent signal reception quality may include, but are not limited to, at least one of the following: reference signal receiving power (RSRP), reference signal receiving quality (RSRQ), or received signal strength indication (RSSI).

[0126] In this embodiment, the reception time of the first synchronization block is earlier than the reception time of the second synchronization block (or may be referred to as the second synchronization signal or the second synchronization signal block), or the transmission time of the first synchronization block is earlier than the transmission time of the second synchronization block, or the time-domain position of the first synchronization block is earlier than the time-domain position of the second synchronization block. It can be understood that the time-domain position of the first synchronization block being earlier than the time-domain position of the second synchronization block can mean that the time-domain position of the first synchronization block is earlier than the time-domain position of the second synchronization block. For example, the location of the time-domain resources used to carry the first synchronization block is earlier than the location of the time-domain resources used to carry the second synchronization block, or the transmission time of the first synchronization block is earlier than the transmission time of the second synchronization block, or the reception time of the first synchronization block is earlier than the reception time of the second synchronization block. For example, the synchronization block can be an SSB, or it can be other signal blocks.

[0127] Optionally, the time domain location of the first synchronization block being earlier than the time domain location of the second synchronization block can also be described as any of the following: the location of the time domain resource carrying the first synchronization block is earlier than the location of the time domain resource carrying the second synchronization block, the time when the terminal device receives the first synchronization block is earlier than the time when the terminal device receives the second synchronization block, or the time when the network device sends the first synchronization block is earlier than the time when the network device sends the second synchronization block.

[0128] It is understood that the network device periodically sends synchronization blocks, and within each period (or synchronization block period, or synchronization block transmission period), the network device can send multiple synchronization blocks. After receiving at least one synchronization block from these multiple synchronization blocks, the terminal device can measure the signal reception quality corresponding to the at least one synchronization block. Then, based on the signal reception quality corresponding to the at least one synchronization block, the terminal device can select the synchronization block with the highest corresponding signal reception quality from the at least one synchronization block, and can designate the synchronization block with the highest corresponding signal reception quality as the first synchronization block. The highest signal reception quality is greater than or equal to a first threshold. Optionally, the terminal device can also select one or more synchronization blocks with a signal reception quality greater than or equal to the first threshold from the at least one synchronization block. Then, the terminal device can select one synchronization block from these one or more synchronization blocks as the first synchronization block. Furthermore, the terminal device can randomly select a preamble from the preamble set as the preamble carried in the first message, or use the index of the preamble as the preamble index carried in the first message. For example, the preamble set may include one or more preambles. Alternatively, the preamble set may include one or more preamble indices.

[0129] It is understandable that there is a mapping relationship (or correspondence) between synchronization blocks and random access opportunities. For example, the mapping relationship between synchronization blocks and random access opportunities can be one-to-many, meaning that one synchronization block can correspond to multiple random access opportunities, such as the first synchronization block corresponding to multiple random access opportunities. Alternatively, the mapping relationship between synchronization blocks and random access opportunities can also be many-to-one, meaning that multiple synchronization blocks correspond to one random access opportunity, such as multiple synchronization blocks containing the first synchronization block corresponding to one random access opportunity. In addition, there is also a mapping relationship between preambles (or preamble indices) and random access opportunities. For example, a preamble in a preamble set can be mapped to a specific random access opportunity corresponding to a synchronization block (such as the first synchronization block), or multiple preambles in a preamble set can be mapped to that specific random access opportunity. For example, consider a preamble set comprising 16 preambles (e.g., preamble #0, preamble #1, preamble #2, ..., preamble 15), with one synchronization block corresponding to four random access opportunities (e.g., RO#a, RO#b, RO#c, and RO#d). Preambles #0 to #3 are mapped to RO#a, preambles #4 to #7 to RO#b, preambles #8 to #11 to RO#c, and preambles #12 to #15 to RO#d. As another example, consider a preamble set comprising four preambles (e.g., preamble #0, preamble #1, preamble #2, and preamble 3), with one synchronization block corresponding to four random access opportunities (e.g., RO#a, RO#b, RO#c, and RO#d). Among them, preamble #0 is mapped to RO#a, preamble #1 is mapped to RO#b, preamble #2 is mapped to RO#c, and preamble #3 is mapped to RO#d.

[0130] Optionally, after determining the first synchronization block, the terminal device can determine at least one random access opportunity corresponding to the first synchronization block based on the mapping relationship between the synchronization block and the random access opportunity. Then, the terminal device can determine which preamble(s) (or preamble(s)) in the preamble set corresponds to each of the at least one random access opportunity corresponding to the first synchronization block, based on the mapping relationship between the preamble(s) or preamble(s) index and the random access opportunity. Then, the terminal device can determine the first random access opportunity corresponding to the preamble(s) or preamble(s) index selected by the terminal device (or the preamble(s) index used by the terminal device) among the at least one random access opportunity corresponding to the first synchronization block. Further, the terminal device can send a first message on the first random access opportunity.

[0131] For example, taking a synchronization block as an SSB, one SSB corresponds to four random access opportunities, and four preamble indices correspond to one random access opportunity. Let's assume the terminal device selects preamble index 2. After determining the first SSB, the terminal device can determine the four ROs corresponding to the first SSB based on the mapping relationship of one SSB to four ROs. For example, the four ROs corresponding to the first SSB might be RO#a, RO#b, RO#c, and RO#d. Then, based on the mapping relationship of four preamble indices to one RO, the terminal device can determine which four preamble indices in the preamble set each of the four ROs corresponding to the first SSB corresponds to. Then, the terminal device can determine the RO corresponding to preamble index #2 among the four ROs corresponding to the first SSB; for example, preamble index #2 corresponds to RO#a. Further, the terminal device can send the first message on RO#a.

[0132] (2) The second random access opportunity may be determined by the terminal device from at least one random access opportunity corresponding to the second synchronization block based on the preamble or preamble index.

[0133] The signal reception quality of the second synchronization block is also greater than or equal to the first threshold.

[0134] In this embodiment, within one cycle, the terminal device can send one or more first messages. That is, within one cycle, the terminal device can select one or more synchronization blocks from the at least one synchronization block to send a first message based on the signal reception quality of the received synchronization blocks. In different cycles, the terminal device can send multiple first messages. That is, in different cycles, the terminal device can select one or more synchronization blocks from the multiple synchronization blocks to send a first message based on the signal reception quality of the received synchronization blocks. It can be understood that the terminal device can periodically receive synchronization blocks from the network device and can measure the received synchronization blocks to obtain the signal reception quality of the received synchronization blocks.

[0135] In one possible implementation, after the terminal device sends the first message at the first random access opportunity, the terminal device may resend (or retransmit) the first message, or the terminal device may send the first message multiple times. For example, after the terminal device sends the first message using the first random access opportunity in the previous (or earlier) instance, it may select the synchronization block with the highest signal reception quality among the multiple synchronization blocks as the second synchronization block based on the signal reception quality of the received synchronization blocks. After determining the second synchronization block, the terminal device may determine at least one random access opportunity corresponding to the second synchronization block based on the mapping relationship between the synchronization block and the random access opportunity. Then, the terminal device may determine which one or more preambles (or preamble indices) in the preamble set correspond to each random access opportunity corresponding to the at least one random access opportunity corresponding to the second synchronization block, based on the mapping relationship between the preamble or preamble index and the random access opportunity. Then, the terminal device may determine the second random access opportunity corresponding to the preamble or preamble index selected by the terminal device among the at least one random access opportunity corresponding to the second synchronization block. Further, the terminal device may send the first message at the second random access opportunity. It is understandable that if the first synchronization block and the second synchronization block belong to the same period, then the first synchronization block and the second synchronization block are different. If the first synchronization block and the second synchronization block belong to different periods, then the first synchronization block and the second synchronization block can be the same, or the first synchronization block and the second synchronization block can be different.

[0136] Optionally, the terminal device may also select one or more synchronization blocks from the plurality of synchronization blocks whose signal reception quality is greater than or equal to a first threshold, based on the signal reception quality of the plurality of synchronization blocks. Then, the terminal device may select one of the one or more synchronization blocks as a second synchronization block. After determining the second synchronization block, the terminal device may determine at least one random access opportunity corresponding to the second synchronization block based on the mapping relationship between synchronization blocks and random access opportunities. Then, the terminal device may determine which one or more preambles (or preamble indices) in the preamble set correspond to each of the at least one random access opportunity corresponding to the second synchronization block, based on the mapping relationship between preambles or preamble indices and random access opportunities. Next, the terminal device may determine the second random access opportunity corresponding to the preamble or preamble index selected by the terminal device from the at least one random access opportunity corresponding to the second synchronization block. Further, the terminal device may send a first message on the second random access opportunity. It is understood that if the first synchronization block and the second synchronization block belong to the same period, then the first synchronization block and the second synchronization block are not the same. If the first synchronization block and the second synchronization block belong to different cycles, then the first synchronization block and the second synchronization block can be the same, or the first synchronization block and the second synchronization block can be different.

[0137] In one possible implementation, after the terminal device has previously sent a first message using a first random access opportunity, it can retransmit the first message on a second random access opportunity before detecting (or monitoring) the response message (or second message, message 2, or message B) corresponding to the first message sent on the first random access opportunity within the time window (or response window, or RAR window) corresponding to the first random access opportunity. Correspondingly, the network device can receive the first message on the second random access opportunity before sending the response message corresponding to the first message within the time window corresponding to the first random access opportunity. For example, the time window corresponding to the first random access opportunity can refer to the RAR window corresponding to the first message sent on the first random access opportunity. Exemplarily, the response message corresponding to the first message may include information about the received preamble, timing advance (TA), uplink grant (UL grant), and temporary cell radio network temporary identifier (TC-RNTI). The TA is used by the terminal device to perform uplink timing adjustments to ensure uplink synchronization. A UL grant can indicate the resource location of the physical uplink shared channel (PUSCH) used to transmit a third message (or message 3).

[0138] In another possible implementation, after the terminal device sends the first message using the first random access opportunity (or the previous one), it can resend the first message using the second random access opportunity (or the second one) before the time window corresponding to the first random access opportunity ends. Correspondingly, the network device can receive the first message using the second random access opportunity (or the second one) before the time window corresponding to the first random access opportunity ends. Optionally, after the terminal device sends the first message using the first random access opportunity (or the previous one), it can also resend the first message using a corresponding random access opportunity (such as the third random access opportunity) before message 4 fails to be received. It is understood that existing random access protocols support retransmission of the first message after message 4 fails to be received. Therefore, compared to existing random access protocols, the embodiments of this application can increase the opportunities to send the first message, helping the terminal device to have more opportunities to access the network device, thereby accelerating the terminal device's access to the network device and improving the success rate of the terminal device's access to the network device.

[0139] Optionally, the multiple random access times may also include other random access times (such as a third random access time). Taking the inclusion of a third random access time as an example: After the terminal device sends a first message on a second random access time, it may send the first message again or continue sending it, or it may send the first message multiple times. For example, after the terminal device last sent a first message using the second random access time, it can select the synchronization block with the highest signal reception quality from among the multiple synchronization blocks as the third synchronization block, based on the signal reception quality received from these synchronization blocks. After determining the third synchronization block, the terminal device can determine at least one random access time corresponding to the third synchronization block based on the mapping relationship between synchronization blocks and random access times. Then, the terminal device can determine which preamble(s) (or preamble indices) in the preamble set corresponds to each random access time in the at least one random access time corresponding to the third synchronization block, based on the mapping relationship between preambles or preamble indices and random access times. Finally, the terminal device can determine the third random access time corresponding to the preamble or preamble index selected by the terminal device among the at least one random access time corresponding to the third synchronization block. Furthermore, the terminal device can send the first message on the third random access timing. It is understood that if the third synchronization block and the second synchronization block belong to the same period, then the third synchronization block and the second synchronization block are different. If the third synchronization block and the second synchronization block belong to different periods, then the third synchronization block and the second synchronization block can be the same, or the third synchronization block and the second synchronization block can be different. In addition, the terminal device can also select one or more synchronization blocks from among the multiple synchronization blocks whose signal reception quality is greater than or equal to a first threshold, based on the signal reception quality of the multiple synchronization blocks. Then, the terminal device can select one synchronization block from among the one or more synchronization blocks as the third synchronization block. After determining the third synchronization block, the terminal device can determine at least one random access timing corresponding to the third synchronization block based on the mapping relationship between synchronization blocks and random access timings. Then, the terminal device can determine which preamble(s) (or preamble indices) in the preamble set corresponds to each random access timing in the at least one random access timing corresponding to the third synchronization block, based on the mapping relationship between preambles or preamble indices and random access timings. Next, the terminal device can determine the third random access opportunity corresponding to the preamble or preamble index selected by the terminal device in at least one random access opportunity corresponding to the third synchronization block. Further, the terminal device can send the first message on the third random access opportunity. It is understood that if the third synchronization block and the second synchronization block belong to the same period, then the third synchronization block and the second synchronization block are different. If the third synchronization block and the second synchronization block belong to different periods, then the third synchronization block and the second synchronization block can be the same, or the third synchronization block and the second synchronization block can be different.

[0140] The following example, using multiple random access times including a first random access time and a second random access time, with the synchronization block being SSB, illustrates the implementation process of a terminal device sending a first message at multiple random access times through several possible examples.

[0141] Example e1: When the first SSB and the second SSB belong to the same SSB period, the terminal device can send multiple first messages within one SSB period. That is, the terminal device can send the first message at random access times corresponding to different SSBs within the same SSB period. For example, the terminal device can send the first message at the first random access time corresponding to the first SSB within an SSB period, or it can send the first message at the second random access time corresponding to the second SSB within the same SSB period.

[0142] For example, consider a terminal device receiving four SSBs (SSB#1, SSB#2, SSB#3, and SSB#4) within one SSB cycle. SSB#1's time domain position is earlier than SSB#2's, SSB#2's time domain position is earlier than SSB#3's, and SSB#3's time domain position is earlier than SSB#4's. After receiving the four SSBs, the terminal device can measure them to obtain the signal reception quality of each SSB.

[0143] If the signal reception quality of two of the four SSBs (e.g., SSB#1 and SSB#2) is greater than or equal to a first threshold, the terminal device can use these two SSBs for random access. For example, the terminal device can determine the random access opportunity corresponding to the preamble or preamble index selected by the terminal device in at least one random access opportunity corresponding to SSB#1, such as RO#01. Then, the terminal device can use RO#01 to send a first message. Furthermore, the terminal device can determine the random access opportunity corresponding to the preamble or preamble index selected by the terminal device in at least one random access opportunity corresponding to SSB#2, such as RO#01'. Then, the terminal device can use RO#01' to send a first message. It should be understood that the preamble included in the first message sent using RO#01' is the same as the preamble included in the first message sent using RO#01, or the preamble index included in the first message sent using RO#01' is the same as the preamble index included in the first message sent using RO#01. It can be understood that RO#01 can be a first random access opportunity, and RO#01' can be a second random access opportunity.

[0144] If the signal reception quality of three out of the four SSBs (e.g., SSB#1, SSB#2, and SSB#3) is greater than or equal to a first threshold, the terminal device can use these three SSBs for random access. For example, the terminal device can determine the random access opportunity corresponding to the preamble or preamble index selected by the terminal device in at least one random access opportunity corresponding to SSB#1, such as RO#01. Then, the terminal device can use RO#01 to send a first message. Furthermore, the terminal device can determine the random access opportunity corresponding to the preamble or preamble index selected by the terminal device in at least one random access opportunity corresponding to SSB#2, such as RO#01'. Then, the terminal device can use RO#01' to send a first message. Moreover, the terminal device can determine the random access opportunity corresponding to the preamble or preamble index selected by the terminal device in at least one random access opportunity corresponding to SSB#3, such as RO#01". Then, the terminal device can use RO#01" to send a first message. It should be understood that the preamble included in the first message sent using RO#01” and the preamble included in the first message sent using RO#01' are the same as the preamble included in the first message sent using RO#01, or the preamble index included in the first message sent using RO#01” and the preamble index included in the first message sent using RO#01' are the same as the preamble index included in the first message sent using RO#01. Optionally, RO#01 may refer to a first random access opportunity, RO#01' may refer to a second random access opportunity, and RO#01” may refer to a third random access opportunity.

[0145] Optionally, if the signal reception quality of only one of the four SSBs (e.g., SSB#2) is greater than or equal to the first threshold, the terminal device can use that SSB for random access. For example, the terminal device can determine the random access timing corresponding to the preamble or preamble index, such as RO#01, from at least one random access timing corresponding to SSB#2. Then, the terminal device can use RO#01 to send the first message.

[0146] Example e2: When the first SSB and the second SSB belong to different SSB periods, the terminal device can send multiple first messages within different SSB periods. That is, the terminal device can send the first message at the random access time corresponding to the SSB in different SSB periods. For example, the terminal device can send the first message at the first random access time corresponding to the first SSB in one SSB period, or it can send the first message at the second random access time corresponding to the second SSB in another SSB period.

[0147] For example, suppose a terminal device receives four SSBs (e.g., SSB#1, SSB#2, SSB#3, and SSB#4) in the previous SSB cycle and four SSBs (e.g., SSB#1, SSB#2, SSB#3, and SSB#4) in the subsequent SSB cycle. SSB#1's time domain position is earlier than SSB#2's, SSB#2's time domain position is earlier than SSB#3's, and SSB#3's time domain position is earlier than SSB#4's. For the four SSBs received in the previous SSB cycle, the terminal device measures the signal reception quality of each SSB. If the signal reception quality of any one of the four SSBs (e.g., SSB#2) is greater than or equal to a first threshold, the terminal device can use that SSB for random access. For example, the terminal device can determine the random access opportunity corresponding to the preamble or preamble index selected by the terminal device in at least one random access opportunity corresponding to SSB#2, such as RO#01. Then, the terminal device can send the first message using RO#01. For the four SSBs received in the next SSB cycle, the terminal device measures the signal reception quality of the four SSBs. If the signal reception quality of one of the four SSBs (such as SSB#1 or SSB#2) is greater than or equal to a first threshold, the terminal device can use that SSB for random access. For example, taking the signal reception quality of SSB#1 as greater than or equal to the first threshold, the terminal device can determine the random access opportunity corresponding to the preamble or preamble index selected by the terminal device in at least one random access opportunity corresponding to SSB#1, such as RO#11.

[0148] For the four SSBs received in the previous SSB cycle, if the signal reception quality of two of the four SSBs (e.g., SSB#1 and SSB#2) is greater than or equal to a first threshold, the terminal device can use these two SSBs for random access. For example, the terminal device can determine the random access opportunity corresponding to the preamble or preamble index selected by the terminal device in at least one random access opportunity corresponding to SSB#1, such as RO#01. Then, the terminal device can use RO#01 to send a first message. Furthermore, the terminal device can determine the random access opportunity corresponding to the preamble or preamble index selected by the terminal device in at least one random access opportunity corresponding to SSB#2, such as RO#01'. Then, the terminal device can use RO#01' to send a first message. Optionally, RO#01 and RO#01' can refer to the first random access opportunity.

[0149] For the four SSBs received in the next SSB cycle, if the signal reception quality of two of the four SSBs (e.g., SSB#1 and SSB#3) is greater than or equal to a first threshold, the terminal device can use these two SSBs for random access. For example, the terminal device can determine the random access opportunity corresponding to the preamble or preamble index selected by the terminal device in at least one random access opportunity corresponding to SSB#1, such as RO#11. Then, the terminal device can use RO#11 to send a first message. Furthermore, the terminal device can determine the random access opportunity corresponding to the preamble or preamble index selected by the terminal device in at least one random access opportunity corresponding to SSB#3, such as RO#13. Then, the terminal device can use RO#13 to send a first message. Optionally, RO#11 and RO#13 can refer to a second random access opportunity.

[0150] In this embodiment, after determining the second synchronization block, the terminal device needs to compare the second synchronization block with the first synchronization block, that is, to determine whether the second synchronization block and the first synchronization block belong to the same period. For example, the terminal device can determine whether the second synchronization block and the first synchronization block belong to the same period based on the radio frame occupied by the second synchronization block (or the index of the radio frame occupied by the second synchronization block), the radio frame occupied by the first synchronization block (or the index of the radio frame occupied by the first synchronization block), and the transmission period of the synchronization block. For example, taking radio frame a occupied by the first synchronization block as radio frame a and radio frame b occupied by the second synchronization block as an example. If radio frame a and radio frame b are located in the transmission period of the same synchronization block, then the second synchronization block and the first synchronization block belong to the same period. If radio frame a is located in period T1 and radio frame b is located in period T2, then the second synchronization block and the first synchronization block belong to different periods. Here, period T2 is a period located after period T1. Optionally, the radio frames occupied by the second synchronization block can be replaced by radio frames described as carrying the second synchronization block, and the radio frames occupied by the first synchronization block can be replaced by radio frames described as carrying the first synchronization block.

[0151] If the second synchronization block and the first synchronization block belong to the same cycle, then the first power ramp-up count is the same as the second power ramp-up count. The first power ramp-up count is used to determine the first transmit power (or first transmission power), which is used by the terminal device to transmit the first message during the first random access opportunity. The second power ramp-up count is used to determine the second transmit power (or second transmission power), which is used by the terminal device to transmit the first message during the second random access opportunity.

[0152] If the second synchronization block and the first synchronization block belong to different cycles, then the second power climb count is equal to the sum of the first power climb count and M, where M is a preset positive integer. The first power climb count is used to determine the first transmission power, which is used by the terminal device to transmit the first message during the first random access opportunity. The second power climb count is used to determine the second transmission power, which is used by the terminal device to transmit the first message during the second random access opportunity.

[0153] The following examples illustrate the specific implementation of the terminal device sending the first message at the first random access time and the second random access time.

[0154] Example f1: When the second synchronization block and the first synchronization block belong to the same cycle, the terminal device uses a first transmit power to transmit a first message at a first random access opportunity. The terminal device uses a second transmit power to transmit the first message at a second random access opportunity. The first transmit power is related to the terminal device's maximum transmit power and a first target receive power. The first target receive power is related to one or more of the following: an initial target receive power, a power offset related to the preamble format, a first power ramp-up count, or a power ramp-up step size. The second transmit power is related to the terminal device's maximum transmit power and the second target receive power. The second target receive power is related to one or more of the following: an initial target receive power, a power offset related to the preamble format, a second power ramp-up count, or a power ramp-up step size.

[0155] It is understandable that, in example f1, the number of power climbs for the first power climb is the same (or equal to) the number of power climbs for the second power climb.

[0156] Example f2: When the second synchronization block and the first synchronization block belong to different periods, the terminal device uses a first transmit power to transmit a first message at a first random access time. The terminal device uses a second transmit power to transmit the first message at a second random access time. The first transmit power is related to the terminal device's maximum transmit power and a first target receive power. The first target receive power is related to one or more of the following: an initial target receive power, a power offset related to the preamble format, a first power climb count, or a power climb step size. The second transmit power is related to the terminal device's maximum transmit power and a second target receive power. The second target receive power is related to one or more of the following: an initial target receive power, a power offset related to the preamble format, a second power climb count, or a power climb step size.

[0157] It's understandable that in example f2, the number of power climbs in the first power climb is different from the number of power climbs in the second power climb. For instance, the number of power climbs in the second power climb is equal to the sum of the number of power climbs in the first power climb and M. For example, if M is 1, then the number of power climbs in the second power climb is equal to the number of power climbs in the first power climb plus 1.

[0158] It is understood that, in the embodiments of this application, the first synchronization block and the second synchronization block refer to any two synchronization blocks among the multiple synchronization blocks received by the terminal device whose signal reception quality is greater than or equal to the first threshold.

[0159] For example, the first transmission power or the second transmission power can satisfy the following formula: P PRACH =min{P CMAX,c (i),P PRACH,target +P L}

[0160] Among them, P PRACH This represents the first or second transmission power, min{} represents the minimum value operation, P CMAX,c (i) represents the maximum transmit power of the terminal device in subframe i, P PRACH,target This represents the target received power calculated by the terminal device (or it can be called the preamble sequence target received power or preamble target received power, such as the first target received power or the second target received power, preamble_Received_Target_Power), P L This represents the downlink path loss calculated by the terminal device. For example, the downlink path loss can be determined by the terminal device based on the received and transmitted power of the downlink signal, or it can be determined by the received and transmitted signal quality of the downlink signal.

[0161] Among them, P PRACH,target =P 初始 +P 偏移 +(C-1)×S step .

[0162] Among them, P 初始 P represents the initial target received power (or preamble initial target received power, or preamble initial target received power). 偏移 The power offset (DELTA_PREAMBLE) is related to the preamble format, C represents the power ramp-up count (Power_Ramping_Counter), and S... step This indicates the power ramping step.

[0163] Optionally, after sending a first message at multiple random access points, the terminal device can detect the response message corresponding to the first message sent at each random access point within a time window corresponding to that random access point. That is, the terminal device can detect multiple time windows simultaneously (or in parallel). However, since the terminal device has limited time window detection capabilities, if the number of time windows corresponding to multiple random access points exceeds the number of time windows supported by the terminal device, the terminal device can select N time windows that satisfy the first condition from the time windows corresponding to multiple random access points. Then, the terminal device can detect the response message corresponding to the first message within the N time windows. The N time windows can be one or more of the time windows corresponding to multiple random access points. It should be understood that each random access point can correspond to one time window. For example, each random access point corresponding to one time window can refer to the RAR window corresponding to the first message sent at each random access point.

[0164] For example, the first condition may include one of the following conditions g1 or g2:

[0165] Condition g1: The signal reception quality of the synchronization block corresponding to the time window is greater than the second threshold. The second threshold can be greater than the first threshold.

[0166] For example, the terminal device can select at least one time window from multiple random access opportunities where the signal reception quality of the corresponding synchronization block is greater than a second threshold. Then, the terminal device can select N time windows from this at least one time window.

[0167] Optionally, the terminal device may also directly select N time windows in which the signal reception quality of the corresponding synchronization block is greater than the second threshold from the time windows corresponding to multiple random access opportunities.

[0168] Condition g2: The synchronization block corresponding to the time window belongs to the first P blocks in the signal reception quality ranking list. The signal reception quality ranking list can include multiple synchronization blocks sorted from highest to lowest signal reception quality. Here, P is a positive integer greater than or equal to N.

[0169] For example, the terminal device can select the first P synchronization blocks from the signal reception quality ranking table. Then, the terminal device can select N synchronization blocks from the first P synchronization blocks. Finally, the terminal device can use the time windows corresponding to the N random access opportunities of the N synchronization blocks as N time windows.

[0170] Alternatively, the terminal device can directly select the first N synchronization blocks from the signal reception quality ranking table. Then, the terminal device can use the time windows corresponding to the N random access opportunities of the first N synchronization blocks as N time windows.

[0171] Referring to Figure 6a, with the synchronization block as SSB, N = 4, and the four SSBs corresponding to the four time windows located in two groups of SSBs (e.g., SSB group 1 and SSB group 2), and the transmission time interval between adjacent groups of SSBs being 20ms, it can be understood that SSB group 1 and SSB group 2 can be located in the same SSB period, or they can be located in different SSB periods. Assume the four SSBs are SSB#a1, SSB#b1, SSB#c1, and SSB#d1. SSB#a1 and SSB#b1 are located in SSB group 1, and SSB#c1 and SSB#d1 are located in SSB group 2. It can be understood that the signal reception quality corresponding to these four SSBs is greater than or equal to the first threshold. For example, with the signal reception quality as RSRP and the first threshold being -105dBm, this can be considered as an example. Specifically, the RSRP corresponding to SSB#a1 and SSB#b1 is -100dBm, and the RSRP corresponding to SSB#c1 and SSB#d1 is -90dBm. Thus, the RSRP of all four SSBs is greater than the first threshold (-105dBm). Optionally, the signal reception quality corresponding to all four SSBs may also be greater than or equal to the second threshold. Then, the terminal device sends a first message at one random access opportunity corresponding to SSB#a1, one random access opportunity corresponding to SSB#b1, one random access opportunity corresponding to SSB#c1, and one random access opportunity corresponding to SSB#d1. Afterward, the terminal device can detect the four time windows corresponding to these four random access opportunities in parallel. That is, the terminal device can detect the response messages corresponding to the first messages sent at these four random access opportunities in parallel.

[0172] Referring to Figure 6b, assuming the terminal device supports a maximum of 2 RAR windows, uses SSB as the synchronization block, and RSRP as the signal reception quality, and four SSBs (e.g., SSB#a1, SSB#b1, SSB#c1, and SSB#d1) among the multiple SSBs the terminal device can receive have RSRPs greater than a first threshold (e.g., -105dBm). It can be understood that SSB group 1 containing SSB#a1 and SSB#b1 and SSB group 2 containing SSB#c1 and SSB#d1 can be in the same SSB period or in different SSB periods. Specifically, assuming the RSRPs corresponding to SSB#a1 and SSB#b1 are both -100dBm, and the RSRPs corresponding to SSB#c1 and SSB#d1 are both -90dBm, when the terminal device determines that the received RSRP corresponding to SSB#1 is greater than the first threshold, the terminal device can send the first message at a random access opportunity corresponding to SSB#1. Subsequently, the terminal device can activate the RAR window corresponding to SSB#a1 (or, as can be understood, the RAR window corresponding to a random access opportunity of SSB#a1) to detect the response message corresponding to the first message (i.e., detect the response message corresponding to the first message sent at a random access opportunity of SSB#a1). When the terminal device determines that the RSRP corresponding to the received SSB#3 is greater than the first threshold, the terminal device can send the first message at a random access opportunity of SSB#b1. Afterwards, if the current number of RAR windows is less than 2, the terminal device can activate the RAR window corresponding to SSB#b1 (or, as can be understood, the RAR window corresponding to a random access opportunity of SSB#b1) to detect the response message corresponding to the first message (i.e., detect the response message corresponding to the first message sent at a random access opportunity of SSB#b1).

[0173] When the terminal device determines that the RSRP corresponding to the received SSB#c1 is greater than the first threshold, the terminal device can send the first message at a random access opportunity corresponding to SSB#c1. Since the number of RAR windows currently being detected is equal to 2, if the terminal device starts a new RAR window for detection, it will exceed the detection capacity of the RAR windows supported by the terminal device. Therefore, the terminal device can stop detecting one RAR window (which can be understood as the terminal device stopping the detection of one RAR window). For example, the terminal device can select the RAR window corresponding to the SSB with high signal reception quality (such as RSRP) for detection based on the signal reception quality of the SSB, and stop detecting the RAR window corresponding to the SSB with low signal reception quality. In this case, since the RSRP of SSB#a1 corresponding to one of the two RAR windows being detected is the same as the RSRP of SSB#b1 corresponding to the other RAR window, the terminal device can choose one of the two RAR windows to stop detection, for example, the terminal device can choose to stop detecting the RAR window corresponding to SSB#a1. Then, the terminal device can activate the RAR window corresponding to SSB#c1 to detect the response message corresponding to the first message (i.e., detect the response message corresponding to the first message sent during a random access event corresponding to SSB#c1). Optionally, the terminal device can also select the RAR window corresponding to the higher-priority SSB for detection based on the SSB's priority, and stop detecting the RAR window corresponding to the lower-priority SSB. For example, the SSB priority can be determined according to the signal reception quality of the SSBs in descending order or in ascending order.

[0174] When the terminal device determines that the RSRP corresponding to SSB#d1 is greater than a first threshold, the terminal device can send the first message at a random access opportunity corresponding to SSB#d1. Since the number of RAR windows currently being detected is equal to 2, if the terminal device starts a new RAR window for detection, it will exceed the detection capacity of the RAR windows supported by the terminal device. Therefore, the terminal device can stop detecting one RAR window. For example, the terminal device can select the RAR window corresponding to the SSB with high signal reception quality (such as RSRP) for detection based on the signal reception quality of the SSB, and stop detecting the RAR window corresponding to the SSB with low signal reception quality. In this case, since the RSRP of SSB#b1 corresponding to one of the two RAR windows being detected is less than the same as the RSRP of SSB#c1 corresponding to the other RAR window, the terminal device can stop detecting the RAR window corresponding to SSB#b1. Then, the terminal device can start the RAR window corresponding to SSB#d1 to detect the response message corresponding to the first message (i.e., detect the response message corresponding to the first message sent at a random access opportunity corresponding to SSB#d1). Optionally, the terminal device can also select the RAR window corresponding to the SSB with higher priority for detection based on the priority of the SSB, and stop detecting the RAR window corresponding to the SSB with lower priority.

[0175] Optionally, if the terminal device successfully parses any received response message (or successfully receives any response message), the terminal device can send a third message (or message 3) based on the content carried by the successfully parsed response message. Simultaneously, the terminal device will terminate (or stop) other ongoing time window detections and may prohibit (or stop) subsequent first message transmissions until the random access procedure using the synchronization block corresponding to the successfully parsed response message succeeds or fails.

[0176] For example, taking the aforementioned N time windows as an example. If the terminal device detects a first response message corresponding to the first message within the first time window of the N time windows that meets the second condition, then the terminal device may stop sending the first message and / or stop detecting the response message corresponding to the first message.

[0177] For example, the second condition may include one or more of the following conditions h1 and h2:

[0178] Condition h1: The information in the preamble included in the first response message is the same as the information in the preamble included in the first message.

[0179] For example, if the information of the preamble included in the first response message is the same as the information of the preamble included in the first message, the terminal device can determine that the first response message detected within the first time window was successfully parsed (or successfully received).

[0180] Condition h2: The RA-RNTI included in the first response message is the same as the RA-RNTI stored on the terminal device.

[0181] For example, if the RA-RNTI included in the first response message is the same as the RA-RNTI stored on the terminal device, the terminal device can determine that the first response message detected within the first time window was successfully parsed (or successfully received).

[0182] Optionally, the RA-RNTI stored on the terminal device can be calculated by the terminal device itself. For example, the terminal device can calculate RA-RNTI according to the following formula: RA-RNTI = 1 + s id +14×t id +14×80×f id +14×80×8×ulcarrier_id

[0183] Among them, s id and t id It is related to the number of the time resource where the preamble is located. f id The value of ulcarrier_id is related to the frequency domain resource number where the preamble is located. This frequency domain resource can be at the physical resource block (PRB) level; for example, six PRBs can be considered as one frequency domain resource. The value of ulcarrier_id is related to the carrier number where the preamble is located. If there is only one uplink carrier in a cell, the value of ulcarrier_id can be 0.

[0184] In this embodiment, when calculating whether the number of retransmissions of the first message exceeds a preset threshold, the terminal device may count all retransmissions within the same period as a single retransmission. For example, the preset threshold may refer to the maximum number of preamble transmissions configured by the network device.

[0185] For example, consider a scenario where the terminal device retransmits the first message five times within a given period. When determining whether the number of retransmissions of the first message exceeds a preset threshold, the terminal device can count the five retransmissions within that period as a single retransmission. Thus, the terminal device judges whether the number of retransmissions of the first message exceeds the preset threshold by treating all retransmissions of the first message within a period as a single retransmission.

[0186] As can be seen from steps 501 to 502 above, the terminal device can send the first message at random access times corresponding to multiple synchronization blocks. This increases the chances for the network device (such as a satellite) to receive the first message, thus improving the probability of the network device receiving the first message and further increasing the success rate of the terminal device accessing the network device. Moreover, compared to the excessively long time consumed by existing random access procedures due to the extended SSB period in satellite communication scenarios, this method, by sending the first message multiple times, increases the chances for the network device to receive the first message, giving the terminal device more opportunities to access the network device and increasing the success rate of the terminal device accessing the network device. This reduces the time (or access time) for the terminal device to access the network device. For example, in satellite communication scenarios, it reduces the time for the ground terminal device to access the satellite and improves the success rate of the ground terminal device accessing the satellite. Furthermore, in situations where existing random access protocols do not support (or do not allow) parallel random access, this method, where the terminal device sends the first message at random access times corresponding to multiple synchronization blocks, allows multiple random access processes to be performed in parallel, helping to speed up the terminal device's access to the network device and thus reducing the time for the terminal device to access the network device.

[0187] It is understood that, in order to achieve the functions in the above embodiments, the terminal device and network device include hardware structures and / or software modules corresponding to perform each function. Those skilled in the art should readily recognize that, based on the units and method steps of the various examples described in conjunction with the embodiments disclosed in this application, this application can be implemented in software, hardware, or a combination of hardware and computer software. Whether a function is executed by hardware or by computer software driving hardware depends on the specific application scenario and design constraints of the technical solution.

[0188] Figures 7 and 8 are schematic diagrams of possible communication devices provided in embodiments of this application. These communication devices can be used to implement the functions of terminal devices or network devices in the above method embodiments, and thus can also achieve the beneficial effects of the above method embodiments. For example, the communication device can be a terminal device as shown in Figure 2 or Figure 3, a network device as shown in Figure 2 or Figure 3, or a module (such as a chip) applied to a terminal device or network device.

[0189] The communication device 700 shown in Figure 7 includes a transceiver unit 710 (or a communication module, transceiver module, or communication unit, used for sending and receiving data). Optionally, the communication device 700 shown in Figure 7 may further include a processing unit 720 (or a processing module). The communication device 700 can be used to implement the functions of the terminal device or network device in the method embodiment shown in Figure 5 above. For example, the transceiver unit 710 can perform the receiving and sending actions performed by the terminal device or network device in the method embodiment above. The processing unit 720 can perform other actions besides the sending and receiving actions performed by the terminal device or network device in the method embodiment above.

[0190] When the communication device 700 is used to implement the functions of the terminal device in the method embodiment shown in FIG5: the transceiver unit 710 is used to acquire a first message. The first message may include information about a preamble. The transceiver unit 710 is also used to send the first message at multiple random access times. The multiple random access times may include a first random access time and a second random access time. The first random access time may be selected from the random access time corresponding to the first synchronization block based on the preamble information. The second random access time may be selected from the random access time corresponding to the second synchronization block based on the preamble information. The reception time of the first synchronization block is earlier than the reception time of the second synchronization block. The signal reception quality of both the first and second synchronization blocks is greater than or equal to a first threshold. The processing unit 720 is used to perform corresponding processing operations, such as calling the transceiver unit 710 to execute the transmission and reception actions required by the terminal device in the method embodiment shown in FIG5, or selecting multiple random access times, etc.

[0191] When the communication device 700 is used to implement the functions of the network device in the method embodiment shown in FIG5 above: the transceiver unit 710 is used to receive the first message at multiple random access times. The multiple random access times may include a first random access time and a second random access time. The first random access time may be selected from the random access time corresponding to the first synchronization block based on the information of the preamble. The second random access time may be selected from the random access time corresponding to the second synchronization block based on the information of the preamble. The reception time of the first synchronization block is earlier than the reception time of the second synchronization block. The signal reception quality of both the first and second synchronization blocks is greater than or equal to a first threshold. The processing unit 720 is used to perform corresponding processing operations, such as calling the transceiver unit 710 to execute the transmission and reception actions required by the network device in the method embodiment shown in FIG5 above, or generating a response message corresponding to the first message, etc.

[0192] For a more detailed description of the processing unit 720 and the transceiver unit 710, please refer to the relevant description in the method embodiment shown in Figure 5 above, which will not be repeated here.

[0193] It should be understood that the transceiver unit 710 in the embodiments of this application can be implemented by an interface circuit or interface circuit-related circuit components, and the processing unit 720 can be implemented by a processor or processor-related circuit components.

[0194] It should be noted that the module division in the embodiments of this application is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods. Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, exist as separate physical entities, or have two or more units integrated into one unit. The integrated units described above can be implemented in hardware or as software functional units.

[0195] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it 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 all or part 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, or a server, etc.) or processor to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0196] The communication device 800 shown in Figure 8 includes a processor 820 and an interface circuit 810. The processor 820 and the interface circuit 810 are coupled to each other. It can be understood that the interface circuit 810 can be a transceiver or an input / output interface. Optionally, the communication device 800 may also include a memory 830 for storing instructions executed by the processor 820, or storing input data required by the processor 820 to execute instructions, or storing data generated after the processor 820 executes instructions.

[0197] When the communication device 800 is used to implement the method embodiment shown in FIG5 above, the processor 820 is used to implement the function of the processing unit 720 above, and the interface circuit 810 is used to implement the function of the transceiver unit 710 above.

[0198] For example, taking the terminal device as the UE and the network device as the base station as an example. When the aforementioned communication device is a chip applied to the UE, the UE chip implements the functions corresponding to the UE in the above method embodiments. For example, when the UE chip receives information from the base station, it can be understood that the information is first received by other modules in the UE (such as radio frequency modules or antennas), and then sent to the UE chip by these modules. When the UE chip sends information to the base station, it can be understood that the information is first sent to other modules in the UE (such as radio frequency modules or antennas), and then sent to the base station by these modules.

[0199] When the aforementioned communication device is a chip applied to a base station, the base station chip implements the functions corresponding to the base station in the above method embodiments. For example, when the base station chip receives information from the UE, it can be understood that the information is first received by other modules in the base station (such as an RF module or antenna), and then sent to the base station chip by these modules. When the base station chip sends information to the UE, it can be understood that the information is sent down to other modules in the base station (such as an RF module or antenna), and then sent to the UE by these modules.

[0200] In this application, entity A sends information to entity B, either directly or indirectly through other entities. Similarly, entity B receives information from entity A, either directly or indirectly through other entities. Entities A and B can be terminal devices or network devices, or modules within those devices. For example, consider terminal devices and network devices. Information transmission and reception can be between a terminal device and a network device, such as between a UE and a base station. Information transmission and reception can also be between two base stations, such as between a CU and a DU. Furthermore, information transmission and reception can be between different modules within a single device, such as between a UE chip and other UE modules, or between a base station chip and other modules within that base station.

[0201] Based on the same concept, this application also provides a possible communication system. This communication system may include one or more terminal devices or network devices. The terminal device can be used to implement the technical solutions related to the terminal device in the above embodiments, and the network device can be used to implement the technical solutions related to the network device in the above embodiments.

[0202] Based on the same concept, this application also provides a computer program product, which includes a computer program or instructions that, when run on a communication device (or computer), cause the communication device (or computer) to perform the methods provided in the above embodiments.

[0203] Based on the same concept, embodiments of this application also provide a computer-readable storage medium storing a computer program or instructions that, when executed by a communication device (or computer), cause the communication device (or computer) to perform the methods provided in the above embodiments.

[0204] Based on the same concept, embodiments of this application also provide a chip system including a processor for supporting a computer device in implementing the methods provided in the above embodiments. In one possible implementation, the chip system further includes a memory for storing necessary programs and data of the computer device. The chip system may be composed of chips or may include chips and other discrete devices.

[0205] The storage medium can be any available medium that a computer can access. For example, but not limited to, a computer-readable medium can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage media or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer.

[0206] Based on the same concept, embodiments of this application also provide a chip, which may include a processor and a memory (or the chip may be coupled to the memory). The processor executes program instructions in the memory to cause the chip to perform the methods provided in the above embodiments. Here, "coupling" means that two components are directly or indirectly connected to each other, such as coupling can refer to an electrical connection between two components.

[0207] Based on the same concept, embodiments of this application also provide a chip system, which includes a processor for supporting a computer device in implementing the functions involved in the terminal device or network device in the above embodiments. In one possible implementation, the chip system further includes a memory for storing necessary programs and data of the computer device. This chip system may be composed of chips or may include chips and other discrete components.

[0208] It is understood that the processor in the embodiments of this application can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. A general-purpose processor can be a microprocessor or any conventional processor.

[0209] The method steps in the embodiments of this application can be implemented in hardware or by a processor executing software instructions. The software instructions can consist of corresponding software modules, which can be stored in random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, registers, hard disks, portable hard disks, compact disc read-only memory (CD-ROM), or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and storage medium can reside in an ASIC. Additionally, the ASIC can reside in a terminal device or a network device. Alternatively, the processor and storage medium can exist as discrete components in the terminal device or network device.

[0210] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer programs or instructions. A computer program is a set of instructions that directs each step of an action of an electronic computer or other device with message processing capabilities. It is typically written in a programming language and runs on a target architecture. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of this application are performed, in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer program or instructions can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, the computer program or instructions can be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless 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 integrates one or more available media. The available medium can be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; it can also be an optical medium, such as a digital video optical disc; or it can be a semiconductor medium, such as a solid-state drive. The computer-readable storage medium can be volatile or non-volatile, or it can include both types of storage media.

[0211] In the various embodiments of this application, unless otherwise specified or in case of logical conflict, the terminology and / or descriptions of different embodiments are consistent and can be referenced by each other. The technical features of different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0212] In this application, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. In the textual description of this application, the character " / " generally indicates an "or" relationship between the preceding and following related objects; in the formulas of this application, the character " / " indicates a "division" relationship between the preceding and following related objects.

[0213] It is understood that the various numerical designations used in the embodiments of this application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application. The order of the process numbers described above does not imply the order of execution; the execution order of each process should be determined by its function and internal logic.

Claims

1. A communication method, characterized in that, Applied to a terminal device, the method includes: Obtain the first message, which includes information about the preamble; Send the first message at multiple random access points; The plurality of random access opportunities include a first random access opportunity and a second random access opportunity. The first random access opportunity is selected from the random access opportunity corresponding to the first synchronization block based on the information of the preamble. The second random access opportunity is selected from the random access opportunity corresponding to the second synchronization block based on the information of the preamble. The reception time of the first synchronization block is earlier than the reception time of the second synchronization block. The signal reception quality of both the first synchronization block and the second synchronization block is greater than or equal to a first threshold.

2. The method as described in claim 1, characterized in that, Sending the first message at multiple random access opportunities includes: The first message is transmitted using a first transmit power at the first random access opportunity; wherein the first transmit power is related to the maximum transmit power of the terminal device and the first target receive power; the first target receive power is related to one or more of the following: initial target receive power, power offset related to the preamble format, first power ramp-up number, or power ramp-up step size; The first message is transmitted using a second transmit power at the second random access time; wherein the second transmit power is related to the maximum transmit power of the terminal device and the second target receive power; the second target receive power is related to one or more of the following: initial target receive power, power offset related to the preamble format, second power ramp number, or power ramp step size.

3. The method as described in claim 2, characterized in that, When the first synchronization block and the second synchronization block are in the same cycle, the number of first power ramps is the same as the number of second power ramps.

4. The method as described in claim 2, characterized in that, When the first synchronization block and the second synchronization block are in different cycles, the second power ramp-up number is equal to the sum of the first power ramp-up number and M, where M is a preset positive integer.

5. The method according to any one of claims 1-4, characterized in that, The method further includes: The response message corresponding to the first message is detected within N time windows; wherein, the N time windows are one or more of the time windows corresponding to the plurality of random access opportunities.

6. The method as described in claim 5, characterized in that, The method further includes: If the number of time windows corresponding to the plurality of random access opportunities is greater than the number of time windows supported by the terminal device, then select the N time windows that satisfy the first condition from the time windows corresponding to the plurality of random access opportunities.

7. The method as described in claim 6, characterized in that, The first condition includes: The signal reception quality of the synchronization block corresponding to the time window is greater than the second threshold, and the second threshold is greater than the first threshold; or... The synchronization block corresponding to the time window belongs to the first P of the signal reception quality sorting table. The signal reception quality sorting table includes multiple synchronization blocks sorted from high to low signal reception quality, where P is a positive integer greater than or equal to N.

8. The method according to any one of claims 5-7, characterized in that, The method further includes: If the first response message corresponding to the first message detected within the first time window of the N time windows satisfies the second condition, then the sending of the first message and / or the detection of the response message corresponding to the first message is stopped; The second condition includes one or more of the following: The information of the preamble included in the first response message is the same as the information of the preamble included in the first message. The first response message includes a Random Access Radio Network Temporary Identifier (RA-RNTI) that is the same as the RA-RNTI stored on the terminal device.

9. The method according to any one of claims 5-8, characterized in that, Sending the first message at multiple random access opportunities includes: The first message is sent at the first random access opportunity; Before the response message corresponding to the first message is detected within the time window corresponding to the first random access opportunity, the first message is sent during the second random access opportunity; or... The first message is sent during the second random access opportunity before the time window corresponding to the first random access opportunity ends.

10. A communication method, characterized in that, Applied to a network device, the method includes: Receive the first message at multiple random access points; The plurality of random access opportunities include a first random access opportunity and a second random access opportunity. The first random access opportunity is selected from the random access opportunity corresponding to the first synchronization block based on the information of the preamble. The second random access opportunity is selected from the random access opportunity corresponding to the second synchronization block based on the information of the preamble. The reception time of the first synchronization block is earlier than the reception time of the second synchronization block. The signal reception quality of both the first synchronization block and the second synchronization block is greater than or equal to a first threshold.

11. The method as described in claim 10, characterized in that, Receiving the first message at multiple random access times includes: The first message is received during the first random access opportunity, and the first message received during the first random access opportunity is transmitted using a first transmission power; wherein, the first transmission power is related to the maximum transmission power of the terminal device and the first target reception power; the first target reception power is related to one or more of the following: initial target reception power, power offset related to the preamble format, first power ramp-up number, or power ramp-up step size; The first message is received during the second random access opportunity, and the first message received during the second random access opportunity is transmitted using a second transmit power; wherein the second transmit power is related to the maximum transmit power of the terminal device and the second target receive power; the second target receive power is related to one or more of the following: initial target receive power, power offset related to the preamble format, second power ramp number, or power ramp step size.

12. The method as described in claim 11, characterized in that, When the first synchronization block and the second synchronization block are in the same cycle, the number of first power ramps is the same as the number of second power ramps.

13. The method as described in claim 11, characterized in that, When the first synchronization block and the second synchronization block are in different cycles, the second power ramp-up number is equal to the sum of the first power ramp-up number and M, where M is a preset positive integer.

14. The method according to any one of claims 10-13, characterized in that, Receiving the first message at multiple random access times includes: The first message is received at the first random access opportunity; Before sending the response message corresponding to the first message within the time window corresponding to the first random access opportunity, the first message is received during the second random access opportunity; or... The first message is received during the second random access opportunity before the time window corresponding to the first random access opportunity ends.

15. A communication device, characterized in that, It includes modules or units for performing the method as described in any one of claims 1-9, or modules or units for performing the method as described in any one of claims 10-14.

16. A communication device, characterized in that, Includes processor and interface circuitry; The interface circuit is used to receive signals from other communication devices and transmit them to the processor, or to send signals from the processor to other communication devices. The processor is configured to implement the method as described in any one of claims 1-9 or the method as described in any one of claims 10-14 through logic circuits or execution code instructions.

17. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program or instructions that, when executed by a communication device, cause the method as described in any one of claims 1-9 or the method as described in any one of claims 10-14 to be implemented.

18. A computer program product, characterized in that, The computer program product includes a computer program or instructions that, when executed on a communication device, cause the method as described in any one of claims 1-9 or the method as described in any one of claims 10-14 to be implemented.

19. A chip, characterized in that, The chip includes a processor coupled to a memory, the processor being configured to execute a computer program or instructions stored in the memory to implement the method as claimed in any one of claims 1-9 or the method as claimed in any one of claims 10-14.

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