Method for sending preamble in random access process, apparatus, and system

Abstract

The present invention relates to the technical field of communications, and disclosed are a method for sending a preamble in a random access process, an apparatus, and a system, for use in solving the problems that a downlink path loss measured by a terminal device in a UL only TRP scenario is higher than an actual uplink path loss, and if the terminal device increases a transmission power during retransmission of the preamble, a delay of the random access process is prolonged, reducing the efficiency of the random access process. The method comprises: in a random access process, a terminal device selecting a beam for sending a preamble, and sending the preamble, wherein the random access process at least comprises initial transmission of the preamble, and at least one retransmission of the preamble after the initial transmission of the preamble when no random access response (RAR) is received in an RAR window; and after the initial transmission of the preamble when no RAR is received in the RAR window, selecting a beam different from a beam for initial transmission of the preamble to perform at least one retransmission of the preamble. The solution of the present application can be widely applied to the technical field of communications, and fields such as artificial intelligence, the Internet of Vehicles, and the Internet of smart home.

Description

Method, device and system for sending preamble code in random access process

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on January 12, 2024, with application number 202410053194.5 and application name “A method, device and system for sending a preamble code in a random access process”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of communications, and in particular to a method, device, and system for sending a preamble code in a random access process. Background Art

[0003] Random access (RA) is used to achieve link time synchronization between terminal devices and network devices, and for network devices to perceive the presence of terminal devices. In the NR system, the terminal device sends a random access preamble on the physical random access channel (PRACH). If the network device correctly receives and demodulates the preamble sent by the terminal device, the network device will send a random access response (RAR) to the preamble to the terminal device. Conversely, if the network device does not correctly receive and demodulate the preamble sent by the terminal device, then if the terminal device does not receive the RAR within the random access response window (RA-response window), it can be considered that the preamble transmission has failed. After the preamble transmission fails, the terminal device can retransmit the preamble, and the terminal device can increase the transmission power of the preamble when retransmitting the preamble.

[0004] In a traditional communication system, a transmission point (TRP) can receive uplink signals sent by a terminal device and send downlink signals to the terminal device. In order to improve the uplink throughput of the communication system, a new type of network device for receiving uplink signals is proposed, which is called an uplink-only TRP or asymmetric TRP. The physical location where this new type of network device is deployed is different from that of a traditional TRP. Naturally, the path loss from the terminal device to the uplink-only TRP and the traditional TRP is different. The reference signal used by the terminal device to measure the downlink path loss comes from the traditional TRP, so the downlink path loss measured by the terminal device is greater than the actual uplink path loss. Similarly, the beam used by the uplink-only TRP to receive the beam sent by the terminal device and the traditional TRP are not reciprocal. The beam used by the terminal device to receive the downlink signal sent by the traditional TRP and the beam used to send the uplink signal to the uplink-only TRP are not reciprocal.

[0005] Because the downlink path loss measured by the terminal device is greater than the actual uplink path loss, the power of the terminal device when sending the preamble is relatively high. Therefore, if the terminal device prioritizes increasing the transmit power when retransmitting the preamble, it will increase the delay of the random access process and reduce the efficiency of the random access process. Summary of the Invention

[0006] The embodiments of the present application provide a method, device and system for sending a preamble code in a random access process to solve the problem that the downlink path loss measured by the terminal device in the UL only TRP scenario is higher than the actual uplink path loss. If the terminal device increases the transmission power when the preamble code is retransmitted, the delay of the random access process will be prolonged and the efficiency of the random access process will be reduced.

[0007] To achieve the above objectives, this application adopts the following technical solutions:

[0008] In the first aspect, an embodiment of the present application provides a method for sending a preamble code in a random access process, which can be executed by a terminal device and a functional module or chip in the terminal device. Taking the execution of the terminal device as an example, the method includes: selecting a beam for sending a preamble code in the random access process, and sending the preamble code; wherein the random access process includes at least an initial transmission of the preamble code, and at least one retransmission of the preamble code after the initial transmission of the preamble code when no RAR is received in the random access response window (ra-response window); after the initial transmission of the preamble code, when no RAR is received in the random access response window, selecting a beam different from the beam of the initially transmitted preamble code to retransmit the preamble code at least once.

[0009] Based on the method described in the first aspect, compared to the terminal device retransmitting the preamble by increasing the transmission power of the preamble after the initial transmission of the preamble, the terminal device preferentially selects a beam different from the beam of the initially transmitted preamble to retransmit the preamble at least once. In the uplink only TRP scenario, the downlink path loss measured by the terminal device is greater than the actual uplink path loss, which makes the terminal device transmit a higher power when initially transmitting the preamble. In this case, the reason why the preamble is not correctly demodulated by the uplink only TRP is more likely to be that the terminal device did not select the optimal beam direction during the initial transmission, rather than insufficient transmission power. By replacing the beam different from the beam of the initially transmitted preamble to retransmit the preamble, the possibility of successful random access of the terminal device is increased, thereby achieving the goal of reducing the delay of random access.

[0010] In one possible design, the beam used for sending the preamble code for the first N-1 times is not used as a candidate beam for sending the preamble code for the Nth time, where N is an integer greater than 1, N≤M, and M is the number of available beams.

[0011] Based on this possible design, when the number of times the terminal device sends the preamble code is less than or equal to the number of available beams, the terminal device can traverse different beams of the terminal device to send the preamble code, so that when the terminal device does not receive the RAR within the random access response window after the initial transmission of the preamble code, it will prioritize retransmitting the preamble code in a beam different from the beam of the initial transmission of the preamble code, thereby improving the probability of successful random access of the terminal device and reducing the delay of random access.

[0012] In one possible design, after the preamble code is sent for the Mth time during the random access process, if the RAR is still not received in the random access response window, the preamble code is sent for the M+1th time. The candidate beams for the M+1th transmission include M beams, and the beam used for the previous NM-1 transmissions of the preamble code is not used as a candidate beam for the Nth transmission of the preamble code, M<N≤2M, and M is the number of available beams.

[0013] Based on this possible design, when the terminal device has sent preamble codes on all beams and has not received RAR within the random access response window, the beam that sends the preamble code when sending the preamble code for the M+1th time can be any available beam of the terminal device; at the same time, when the number of times the terminal device sends the preamble code is greater than the number of available beams and less than or equal to 2 times the number of available beams, the terminal device can traverse the beams of the terminal device again to send the preamble code, so that the terminal device can select a beam different from the beam of the initially transmitted preamble code to retransmit the preamble code at least once if no RAR is received within the random access response window after the initial transmission of the preamble code, and further obtain the gain of reducing the random access delay by changing the beam different from the beam of the initially transmitted preamble code to retransmit the preamble code when the transmission power of the initially transmitted preamble code is sufficient.

[0014] In one possible design, the number of preamble power ramps is counted by a preamble power ramp counter. For example, after an integer multiple of M transmissions, that is, after traversing available beams to transmit the preamble, if no RAR is received in the random access response window, the preamble power ramp counter is incremented by one, where M is the number of available beams. For example, M can be 2, 3, 4, and so on.

[0015] Based on this possible design, whether the power of the preamble code sent this time is higher than the power of the preamble code sent last time can be determined by whether the count value of the preamble code power climb times counter changes. In addition, when no RAR is received in the random access response window after each traversal of the available beams, the count value of the preamble code power climb times counter is increased by one, so that the terminal device can traverse the available beams again to send the preamble code with a transmission power higher than the preamble code sent when the available beams are traversed this time, that is, traversing the available beams to send the preamble code is given priority. If no RAR is received after the traversal is completed, it means that the reason for the failure of random access may be insufficient transmission power and the transmission power needs to be increased.

[0016] In one possible design, the number of times the preamble is sent is counted by a preamble sending counter; for example, if no RAR is received in the random access response window after the preamble is sent, that is, if no RAR is received after each transmission, the count value of the preamble sending counter is increased by one.

[0017] In one possible design, if the count value of the preamble code transmission times counter reaches a preset value, the medium access control layer of the terminal device indicates a random access problem or a failure of the random access process to the upper layer of the terminal device.

[0018] Based on this possible design, the terminal device is given the action to perform when the number of preamble transmissions reaches a preset value. The cause of the random access problem may be that the preamble selected by the terminal device conflicts with that of other terminal devices. In this case, the terminal device can resolve the conflict by reselecting a different preamble.

[0019] In one possible design, first indication information is received for indicating a manner of sending a preamble during a random access process. Based on this possible design, the terminal device may receive the indication information and send a preamble during the random access process in the indicated manner, so that the terminal device initially transmits the preamble and retransmits the preamble during the random access process in accordance with the indication.

[0020] In one possible design, the method of sending the preamble code includes selecting a beam different from the beam of the initially transmitted preamble code to retransmit the preamble code at least once after the initial transmission of the preamble code if no RAR is received in the random access response window, that is, sending the preamble code through different beams.

[0021] Based on this possible design, a new method for sending a preamble is provided, further enabling the terminal device to send the preamble in the manner indicated by the instruction information, thereby optimizing the method for sending the preamble. For example, the instruction information may instruct the terminal to send the preamble in the method provided in this application, or the instruction information may instruct the terminal to send the preamble in the method specified by the current wireless protocol, thereby optimizing the method for sending the preamble.

[0022] In one possible design, receiving the first indication information includes receiving downlink signaling from the network device for triggering initiation of a random access procedure to the network device, including the first indication information. For example, downlink control information 1_0 (DCI 1_0) of a physical downlink control channel (PDCCH) of the network device may be received, where the DCI 1_0 carries the first indication information.

[0023] Based on this possible design, the first indication information can be carried in the reserved field of the downlink signaling sent by the network device and indicated to the terminal device, so that the first indication information can be received without increasing the length of the downlink signaling, saving the downlink signaling overhead.

[0024] In one possible design, the first indication information is a 1-bit indication field. Based on this possible design, when the 1-bit indication field is a binary bit 0, the downlink signaling including the first indication information is the same as the downlink signaling specified by the current wireless protocol, thereby achieving the effect of not affecting the terminal device's parsing of the downlink signaling.

[0025] In one possible design, the first indication information occupies one bit in the DCI 1_0 reserved field. When the first indication information is a binary bit 1, the terminal device sends the preamble according to the method provided in this application. When the first indication information is a binary bit 0, the terminal device sends the preamble according to the method specified in the current wireless protocol. Further, through the aforementioned actions, the terminal device can execute the random access procedure preamble sending method provided in this application when instructed by the first indication information.

[0026] In the second aspect, an embodiment of the present application provides a method for sending a preamble code in a random access process. The method can be executed by a network device and a functional module or chip within the network device. Taking execution by a network device as an example, the method includes: sending a first indication information, and the first indication information is used to indicate a method for sending a preamble code in a random access process.

[0027] Based on the method of the second aspect, the network device can implement a method of indicating the sending of a preamble code during random access, so that the terminal device can send the preamble code during random access in the indicated manner, thereby optimizing the method of sending the preamble code.

[0028] In one possible design, the method of sending the preamble code includes selecting a beam different from the beam of the initially transmitted preamble code to retransmit the preamble code at least once if no RAR is received in the random access response window after the initially transmitted preamble code.

[0029] Based on this possible design, a new method for sending a preamble is proposed, further enabling the terminal device to send the preamble in accordance with the preamble method indicated by the network device, thereby optimizing the method for sending the preamble. For example, the network device may instruct the terminal to send the preamble in the method provided in this application, or the instruction information may instruct the terminal to send the preamble in the method specified by the current wireless protocol, thereby optimizing the method for sending the preamble.

[0030] In one possible design, sending the first indication information includes sending downlink signaling including the first indication information for triggering initiation of a random access process to the network device. For example, DCI format 1_0 may be sent on the PDCCH, where the DCI format 1_0 carries the first indication information.

[0031] Based on this possible design, the first indication information can be carried in the downlink signaling sent by the network device to indicate the terminal device, so that the first indication information can be sent to the terminal device without increasing the length of the downlink signaling, saving the downlink signaling overhead.

[0032] In one possible design, the first indication information is a one-bit indication field. Based on this possible design, when the one-bit indication field is a binary bit 0, the downlink signaling including the first indication information is the same as the downlink signaling specified by the current wireless protocol, thereby achieving the effect of not affecting the terminal device's parsing of the downlink signaling.

[0033] In a third aspect, the present application provides a communication device, which may be a terminal device or a chip or system on chip in a terminal device, or a functional module in a terminal device for implementing the method in the first aspect or any possible design of the first aspect. The communication device can implement the functions performed by the terminal device in the above-mentioned first aspect or any possible design of the first aspect, and the functions can be implemented by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above-mentioned functions. For example, the communication device may include a transceiver unit and a processing unit. Among them,

[0034] a processing unit, configured to select a beam for transmitting a preamble during a random access procedure; the random access procedure comprising at least an initial transmission of the preamble, and at least one retransmission of the preamble after the initial transmission of the preamble if no RAR is received in a random access response window; and selecting a beam different from the beam used for the initial transmission of the preamble for at least one retransmission of the preamble if no RAR is received in the random access response window after the initial transmission of the preamble;

[0035] A transceiver unit, configured to send a preamble;

[0036] Specifically, the relevant description of the beam for sending the preamble code can refer to the first aspect or any possible design of the first aspect. At the same time, the execution actions of each unit of the communication device can refer to the first aspect or any possible design of the first aspect and will not be repeated here.

[0037] In a fourth aspect, the present application provides a communication device, which may be a terminal device or a chip or system on chip in a terminal device. The communication device may implement the function performed by the terminal device in the first aspect or the possible design of the first aspect, and the function may be implemented by hardware. In one possible design, the communication device includes a processor and a communication interface. The processor and the communication interface are used to support the communication device in executing the random access process preamble code sending method in the first aspect or any possible design of the first aspect. In another possible design, the communication device may further include a memory, the memory being used to store computer-executable instructions and data necessary for the communication device. When the communication device is running, the processor executes the computer-executable instructions stored in the memory, so that the communication device performs the random access process preamble code sending method as described in the first aspect or any possible design of the first aspect.

[0038] In a fifth aspect, the present application provides a communication device, which may be a network device or a chip or system on chip in a network device, or a functional module in a network device for implementing the second aspect or any possible design of the second aspect. The communication device can implement the functions performed by the network device in the above-mentioned second aspect or any possible design of the second aspect, and the functions can be implemented by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above-mentioned functions. For example, the communication device may include a transceiver unit. Among them,

[0039] The transceiver unit is used to send first indication information, where the first indication information is used to indicate a method for sending a preamble code during a random access process.

[0040] Specifically, the relevant description of the first indication information can refer to the second aspect or any possible design of the second aspect. At the same time, the execution actions of each unit of the communication device can refer to the second aspect or any possible design of the second aspect, and will not be repeated here.

[0041] In a sixth aspect, the present application provides a communication device, which may be a network device or a chip or system on chip in a network device. The communication device may implement the function performed by the network device in the second aspect or any possible design of the second aspect, and the function may be implemented by hardware. In one possible design, the communication device includes a processor and a communication interface. The processor and the communication interface are used to support the communication device in executing the random access process preamble code sending method in the second aspect or any possible design of the second aspect. In another possible design, the communication device may further include a memory, the memory being used to store computer-executable instructions and data necessary for the communication device. When the communication device is running, the processor executes the computer-executable instructions stored in the memory, so that the communication device performs the random access process preamble code sending method in the second aspect or any possible design of the second aspect.

[0042] In the seventh aspect, the present application provides a communication system, which includes the communication device provided by the third aspect and the communication device provided by the fifth aspect; or, the communication system includes the communication device provided by the third aspect and the communication device provided by the sixth aspect; or, the communication device includes the communication device provided by the fourth aspect and the communication device provided by the fifth aspect; or, the communication system includes the communication device provided by the fourth aspect and the communication device provided by the sixth aspect.

[0043] In an eighth aspect, the present application provides a computer-readable storage medium storing computer instructions. When the computer instructions are executed on a computer, the computer executes the method for sending a preamble code for a random access process in the first aspect or any possible design of the first aspect; or, the computer executes the method for sending a preamble code for a random access process in the second aspect or any possible design of the second aspect.

[0044] In a ninth aspect, the present application provides a computer program product comprising computer instructions. When the computer instructions are executed on a computer, the computer executes the random access process preamble code sending method in the first aspect or any possible design of the first aspect; or, the computer executes the random access process preamble code sending method in the second aspect or any possible design of the second aspect.

[0045] The technical effects brought about by any one of the design modes in the third, fourth, seventh, to ninth aspects may refer to the technical effects brought about by the first aspect or any possible design of the first aspect, and will not be repeated here. The technical effects brought about by any one of the design modes in the fifth, sixth, seventh, to ninth aspects may refer to the technical effects brought about by the second aspect or any possible design of the second aspect, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] FIG1 is a schematic diagram of a process of transmitting a preamble in a random access process;

[0047] FIG2 is a schematic diagram of a communication system provided in an embodiment of the present application;

[0048] FIG3 is a schematic diagram of a flow chart of a method for sending a preamble code in a random access process according to an embodiment of the present application;

[0049] FIG4 is a schematic diagram of a flow chart of a method for sending a preamble code in a random access process according to an embodiment of the present application;

[0050] FIG5 is a schematic diagram of a process of sending a preamble provided in an embodiment of the present application;

[0051] FIG6 is a schematic diagram of a process of sending a preamble provided in an embodiment of the present application;

[0052] FIG7 is a schematic structural diagram of a communication device provided in an embodiment of the present application;

[0053] FIG8 is a schematic structural diagram of a communication device provided in an embodiment of the present application;

[0054] FIG9 is a schematic structural diagram of a communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0055] Before introducing the embodiments of the present application, some technical terms involved in the embodiments of the present application are explained. It should be noted that the following explanations are intended to make the embodiments of the present application easier to understand and should not be regarded as limiting the scope of protection claimed by the embodiments of the present application.

[0056] Random access (RA) is used to achieve uplink time synchronization between terminal devices and network devices, and to establish an initial connection between the terminal device and the network device. The random access process includes: the terminal device sends a random access preamble on the physical random access channel (PRACH). If the network device correctly receives and demodulates the preamble sent by the terminal device, the network device will send a response to the preamble (random access response, RAR) to the terminal device. Conversely, if the network device does not correctly receive and demodulate the preamble sent by the terminal device, then if the terminal device does not receive the RAR within the random access response window (RA-response window), it can be considered that the preamble transmission has failed. After the preamble transmission fails, the terminal device can retransmit the preamble, and the terminal device can increase the transmission power of the preamble when retransmitting the preamble.

[0057] The preamble can be alternatively described as a random access preamble, preamble sequence, preamble, or random access request information. The preamble can be carried in the physical random access channel (PRACH) and sent to the network device. The preamble can be assigned to the terminal device by the network device configuration, or the terminal device can randomly select it from a set of preambles.

[0058] The random access response window, also known as the random access response time window or RAR time window, is a time period / time window used to limit the reception of RARs. Receiving an RAR within this random access response window indicates a successful random access. Failure to receive an RAR within this random access response window, or failing to receive an RAR within the random access response window, indicates a failed random access. The network device notifies the terminal device of the configuration information of the random access response window via a broadcast system message.

[0059] The preamble can be alternatively described as message 1 (message1, MSG1); the RAR can be alternatively described as message 2 (message2, MSG2).

[0060] The transmission power of the terminal device transmitting the preamble is determined by the maximum transmission power of the terminal device, the expected receiving power pre-configured by the MAC layer, and the path loss between the terminal device and the network device. For example, taking the case where the terminal device initially transmits the preamble to the network device in the uplink bandwidth part (BWP) b of the carrier f in cell c, the transmission power P of the terminal device for the initial transmission of the preamble is prach,b,f,c(i) Satisfy the following formula (1): P prach,b,f,c (i) = min{P cmax,f,c (i),P prach,target,f,c +PL b,f,c dBm (1)

[0061] In formula (1), P cmax,f,c (i) is the maximum transmit power of the terminal device, P prach,target,f,c The expected received power of PRACH is determined by the high-level parameter PREAMBLE_RECEIVED_TARGET_POWER. b,f,c P is the path loss between the terminal device and the network device. prach,b,f,c (i) is the minimum value of the maximum transmit power of the terminal device, the sum of the expected PRACH receive power and the path loss between the terminal device and the network device.

[0062] Currently, if a terminal device does not receive the RAR sent by the network device in the random access response window after initially transmitting the preamble, it is considered that the initial preamble transmission has failed. At this time, the terminal device can retransmit the preamble by increasing the preamble transmission power or retransmit the preamble by reselecting a new beam. If a new beam is reselected to retransmit the preamble, the preamble transmission power remains unchanged; if the preamble transmission power is increased and retransmitted, the transmission power PREAMBLE_RECEIVED_TARGET_POWER of the retransmitted preamble satisfies the following formula (2):

[0063] PREAMBLE_RECEIVED_TARGET_POWER=preambleReceivedTargetPower+DELTA_PREAMBLE+(PREAMBLE_POWER_RAMPING_COUNTER-1)×PREAMBLE_POWER_RAMPING_STEP+POW ER_OFFSET_2STEP_RA.

[0064] Among them, preambleReceivedTargetPower is the expected received power of the previous preamble code, DELTA_PREAMBLE is the power offset value related to the preamble code format, PREAMBLE_POWER_RAMPING_COUNTER is the count value of the preamble code power ramp times counter, PREAMBLE_POWER_RAMPING_STEP is the incremental step size of the transmit power each time the preamble code is retransmitted, and POWER_OFFSET_2STEP_RA is the offset value related to the random access (RA) type.

[0065] If a new beam is selected to retransmit the preamble, the preamble's transmit power remains unchanged. This means that when the terminal device switches beams to transmit the preamble, the preamble power ramp counter does not count during this preamble transmission. That is, the preamble power ramp counter remains unchanged, and the preamble's transmit power remains unchanged compared to the previous preamble transmission.

[0066] For example, as shown in Figure 1, it is assumed that the beams that the terminal device can use to send preamble codes include two beams, and the transmission directions of the two beams are different. The terminal device performs one initial transmission of the preamble code (or called initial transmission) and four retransmissions of the preamble code to implement the random access process. Among them, the beam of the first retransmitted preamble code is the same as that of the initial transmitted preamble code, but the transmit power of the first retransmitted preamble code is higher than that of the initial transmitted preamble code, so the count value of the preamble code power climb times counter increases from 1 to 2; the beam of the second retransmitted preamble code is the same as that of the first retransmitted preamble code, but the transmit power of the second retransmitted preamble code is higher than that of the first retransmitted preamble code, so the count value of the preamble code power climb times counter increases from 2 to 3; the beam of the third retransmitted preamble code is different from that of the second retransmitted preamble code, but the transmit power of the third retransmitted preamble code is not increased compared to the transmit power of the second retransmitted preamble code, so the preamble code power climb times counter does not count and its count value remains 3; the beam of the fourth retransmitted preamble code is the same as that of the third retransmitted preamble code, but the transmit power of the fourth retransmitted preamble code is higher than that of the third retransmitted preamble code, so the count value of the preamble code power climb times counter increases from 3 to 4.

[0067] The above-mentioned random access process can be applied to a variety of communication systems, for example, it can be applied to a communication system including a terminal device, a traditional base station, and an uplink-only TRP. In this communication system, since the uplink-only TRP is used to receive uplink signals sent by the terminal device but does not support downlink transmission, that is, it does not support sending downlink signals and / or data to the terminal device, it is necessary to use the traditional base station to send downlink signals and / or data to the terminal device. The physical locations of the traditional base station and the uplink-only TRP are different, so that the path loss from the terminal device to the uplink-only TRP and to the traditional base station is different. The reference signal for the terminal device to measure the downlink path loss comes from the traditional base station, so the downlink path loss measured by the terminal device is greater than the actual uplink path loss. Similarly, the traditional base station and the uplink-only TRP support different communication environments and supported communication modes, so that the uplink beam between the terminal device and the uplink-only TRP and the downlink beam between the traditional base station and the terminal device are not reciprocal. When the terminal device transmits a preamble code, it needs to select a beam from several configured beams to transmit the preamble code. In the aforementioned communication system, since the downlink path loss measured by the terminal device is greater than the actual uplink path loss, when the above formula (1) is used to determine the transmission power of the initial transmission preamble code, the transmission power of the initial transmission preamble code of the terminal device is too high. At this time, if the terminal device needs to retransmit the preamble code, the reason for the failure of the previous preamble code transmission is more likely to be that the optimal beam direction was not selected rather than insufficient transmission power. If the transmission power is increased during the retransmission of the preamble code, the delay of the random access process will be prolonged, thereby reducing the efficiency of the random access process.

[0068] In order to solve the problem that the downlink path loss measured by the terminal device in the UL only TRP scenario is higher than the actual uplink path loss, if the terminal device increases the transmission power when retransmitting the preamble code, it will lengthen the delay of the random access process and reduce the efficiency of the random access process. The present application provides a method for sending a preamble code in a random access process, the method comprising: the terminal device selects a beam to initially transmit the preamble code, and after initially transmitting the preamble code, if no RAR is received in the random access response window, the terminal device selects a beam again to retransmit the preamble code at least once; wherein, after initially transmitting the preamble code, if no RAR is received in the random access response window, the terminal device selects a beam different from the beam of the initially transmitted preamble code to retransmit the preamble code at least once. In the uplink only TRP scenario, the downlink path loss measured by the terminal device is greater than the actual uplink path loss, which makes the terminal device's transmission power of the initially transmitted preamble code too high. At this time, the reason why the preamble code is not correctly demodulated by the uplink only TRP is more likely to be that the terminal device did not select the optimal beam direction during the initial transmission, rather than insufficient transmission power. In this way, compared with the terminal device giving priority to retransmitting the preamble code by increasing the transmission power of the preamble code after the initial transmission of the preamble code, the terminal device gives priority to selecting a beam different from the beam of the initially transmitted preamble code to retransmit the preamble code at least once, so that the terminal device can retransmit the preamble code by changing to a beam different from the beam of the initially transmitted preamble code when the transmission power of the initially transmitted preamble code is sufficient, thereby improving the possibility of successful random access of the terminal device and achieving the goal of reducing the delay of random access.

[0069] The following describes the method for sending a preamble code during a random access process provided by an embodiment of the present application in conjunction with the accompanying drawings.

[0070] The technical solution of the embodiment of the present application can be used in various communication systems, which may be a third generation partnership project (3GPP) communication system, for example, a long term evolution (LTE) system, or a fifth generation (5G) mobile communication system, a new radio (NR) system, a beyond 5G (B5G) mobile communication system, a sixth generation (6G) mobile communication system, a new air interface vehicle to everything (NR V2X) system, and can also be applied to a system of LTE and 5G hybrid networking, or a device-to-device (D2D) communication system, a machine-to-machine (M2M) communication system, an Internet of Things (IoT), and other next generation communication systems, or a non-3GPP communication system, without limitation. Below, taking the communication system shown in FIG. 2 as an example, the random access process preamble sending method provided in the embodiment of the present application is described.

[0071] The technical solutions of the embodiments of the present application can be applied to various communication scenarios, for example, one or more of the following communication scenarios: enhanced mobile broadband (eMBB), ultra-reliable low latency communication (URLLC), machine type communication (MTC), massive machine type communications (mMTC), D2D, V2X, and IoT communication scenarios.

[0072] The communication system to which the technical solutions of the embodiments of the present application are applicable may include terminal devices and network devices. It is understood that terminal devices and network devices may communicate directly with each other or through forwarding by other devices, and this embodiment of the present application does not specifically limit this. Figure 2 is a schematic diagram of a communication system provided by an embodiment of the present application. As shown in Figure 2, the communication system 20 may include: network devices and terminal devices.

[0073] It is understood that Figure 2 is merely a schematic diagram and does not limit the applicable scenarios of the technical solutions provided in this application. Those skilled in the art will appreciate that, in a specific implementation, communication system 20 may include fewer devices than shown in Figure 2 , or may include other devices. The number of devices in communication system 20 may also be determined based on specific needs and is not limited. The following describes the devices in the system shown in Figure 2 .

[0074] The terminal equipment may be a user equipment (UE) or a mobile station (MS) or a mobile terminal (MT), etc., including a handheld device, a vehicle-mounted device, a wearable device or a computing device with a wireless communication function. Specifically, the terminal equipment may be a mobile phone, a tablet computer or a computer with a wireless transceiver function, or a virtual reality (VR) terminal, an augmented reality (AR) terminal, a wireless terminal in industrial control, a wireless terminal in unmanned driving, a wireless terminal in telemedicine, a wireless terminal in a smart grid, a wireless terminal in a smart city, a smart home, a vehicle-mounted terminal, etc. In the embodiment of the present application, the device for realizing the function of the terminal device may be a terminal device, or a device that can support the terminal device to realize the function, such as a chip system (such as a processing system composed of a chip or multiple chips) or a modem. The following takes the terminal device as an example to describe the random access process preamble sending method provided in the embodiment of the present application.

[0075] A network device is mainly used to implement functions such as resource scheduling, radio resource management, and radio access control of terminal devices. It is a device in a radio access network (RAN) that connects terminal devices to a wireless network. The RAN can be connected to a core network (for example, an LTE core network or a 5G core network). The network device can be an evolved base station (eNB or eNodeB) in LTE, or a base station in a 5G network or a future evolved public land mobile network (PLMN), or a base station that supports unilateral transmission (for example, an uplink-only TRP or asymmetric TRP that supports uplink transmission but not downlink transmission), or a broadband network gateway (BNG), or an aggregation switch or non-3GPP access device; or the network device in the embodiment of the present application can also be a wireless controller in a cloud radio access network (CRAN); or a transmission and reception point (TRP), or a device including a TRP, etc., which is not specifically limited in the embodiment of the present application. Optionally, the network device in the embodiment of the present application may include various forms of base stations, such as: macro base stations, micro base stations (also known as small stations), relay stations, access points, etc., and the embodiment of the present application does not specifically limit this. In the embodiment of the present application, the device for implementing the function of the network device can be a network device, or it can be a device that can support the network device to implement the function, such as a chip system (such as a chip, or a processing system composed of multiple chips) or a modem. The following takes the device for implementing the function of the network device as an example to describe the random access process preamble code sending method provided by the embodiment of the present application.

[0076] Optionally, each device in Figure 2 (such as a terminal device, a network device) can also be referred to as a communication device, which can be a general device or a dedicated device, and the embodiments of the present application do not specifically limit this.

[0077] Optionally, the related functions of each device in FIG2 of the present application can be implemented by a single device, or by multiple devices, or by one or more functional modules within a single device, and the embodiments of the present application do not specifically limit this. It is understood that the above functions can be network elements in hardware devices, software functions running on dedicated hardware, or a combination of hardware and software, or virtualized functions instantiated on a platform (e.g., a cloud platform).

[0078] The following describes the method for sending a preamble code during random access provided by an embodiment of the present application in conjunction with the communication system shown in FIG2. The actions, terms, etc. involved in the following embodiments can refer to each other. The message names or parameter names in the messages exchanged between devices in each embodiment are only examples, and other names can also be used in specific implementations. For example, "corresponding" in the following embodiments can be replaced with "associated", etc., and "sending" in the following embodiments can be replaced with "transmitting", etc. FIG3 is a flow chart of a method for sending a preamble code during random access provided by an embodiment of the present application. As shown in FIG3, it can include steps S301-S302:

[0079] S301: The terminal device selects a beam for sending a preamble code during a random access process.

[0080] The terminal device may be the terminal device shown in FIG2 , and the terminal device may be in a connected state, an idle state, or an inactive state, without limitation. The terminal device may include M available beams (or uplink beams), which may be alternatively described as candidate beams. The terminal device may select a beam from the M available beams to transmit a preamble, where M is a natural number greater than 1. The value of M depends on the capabilities of the terminal device.

[0081] The random access process includes at least the initial transmission of the preamble, and at least one retransmission of the preamble when the RAR is not received in the random access response window after the initial transmission of the preamble. In the present application, the initial transmission of the preamble may refer to the first transmission of the preamble or the first transmission of the preamble or the initial transmission, etc., and the retransmission may refer to the retransmission of the preamble after the initial transmission of the preamble. When the number of times the preamble is sent is numbered consecutively starting from 1, the initial transmission may refer to the first transmission, and the retransmission may refer to the Nth transmission, where N is an integer greater than 1 or is understood to be an integer greater than or equal to 2, and the Nth transmission may also be replaced by the N-1th retransmission.

[0082] It should be understood that the random access process includes at least an initial transmission of a preamble, and after the initial transmission of the preamble, at least one retransmission of the preamble if no RAR is received in the random access response window. This may refer to: the random access process being the initial transmission of the preamble, or the random access process being the initial transmission of the preamble and at least one retransmission of the preamble. The at least one retransmission may include one retransmission and multiple retransmissions, and the multiple retransmissions may include but are not limited to two retransmissions or three retransmissions, etc.

[0083] In the present application, after initially transmitting a preamble, if no RAR is received in the random access response window, a beam different from the beam used to initially transmit the preamble is selected to retransmit the preamble at least once, so as to traverse different beams to send the preamble and improve the probability of successful random access. Selecting a beam different from the beam used to initially transmit the preamble to retransmit the preamble at least once can be replaced by the description of selecting a beam from a candidate beam to retransmit the preamble, where the candidate beam can be a beam different from the beam used to initially transmit the preamble; or, it can be replaced by the description of traversing different beams to send the preamble or the terminal device traversing and selecting different beams for sending the preamble during the random access process. Alternatively, the description may be replaced by that after initially transmitting the preamble, if the terminal device does not receive an RAR in the random access response window, the terminal device preferentially traverses different beams to retransmit the preamble. Alternatively, the description may be replaced by that after sending the preamble for the first time, if the terminal device does not receive an RAR in the random access response window, the terminal device preferentially retransmits the preamble on other beams. Alternatively, the description may be replaced by that after sending the preamble for the first time, if the terminal device does not receive an RAR in the random access response window and the terminal device has multiple beams, the terminal device preferentially retransmits the preamble on beams other than the beam in which the preamble was sent for the first time. Alternatively, the description may be replaced by that after sending the preamble for the first time, if the terminal device does not receive an RAR in the random access response window and the terminal device has M available beams, the terminal device preferentially retransmits the preamble on beams other than the beam in which the preamble was sent for the first time among the M beams.

[0084] Taking the case where the terminal device includes M available beams as an example, when the number of times N the preamble is sent is an integer greater than 1, and the number of times N the preamble is sent is less than or equal to the number of beams available to the terminal device, M, the beam used for the first N-1 preamble transmissions is not used as a candidate beam for the Nth preamble transmission. If no RAR is received in the random access response window after the Mth preamble transmission in the random access process, the preamble is sent for the M+1th time, i.e., a second round of traversal of preamble transmission using different beams is started. The candidate beams for the M+1th transmission include M beams. In other words, the candidate beams in the second round of traversal are M beams. At this time, the number of times N the preamble is sent is greater than the number of beams available to the terminal device, M, and less than or equal to 2M. The beam used for the first NM-1 preamble transmissions in the second round of traversal is not used as a candidate beam for the Nth preamble transmission. Similarly, if RAR is not received in the random access response window after the K*Mth transmission, the preamble code is sent for the K*M+1th time, that is, the K+1th round of traversing different beams to send the preamble code is started, where K is an integer greater than or equal to 2.

[0085] In the present application, the beam may be described interchangeably as a spatial domain transmission filter, or an uplink beam, or an uplink spatial filter. The number of beams available to a terminal device may be described interchangeably as the number of beams of the terminal device, or the number of spatial transmission filters of the terminal device, or the number of available spatial transmission filters of the terminal device. Different beams correspond to different numbers or index numbers or beam index numbers. The traversal order of different rounds may be the same or different, for example, in the first round, different beams are traversed from small to large according to the numbers, and in the second round, different beams are traversed from large to small, etc., without limitation.

[0086] Specifically, taking the terminal device including M available beams as an example, S301 may include:

[0087] When the random access process is an initial transmission of a preamble, M available beams are used as candidate beams, and the terminal device selects one beam from the M available beams for sending the initial transmission of the preamble. The beam selected by the terminal device for sending the preamble can be any beam among the available beams of the terminal device.

[0088] When the random access process involves the initial transmission of a preamble and a retransmission of the preamble, the terminal device selects one of the M available beams as candidate beams for the initial transmission of the preamble. If no RAR is received in the random access response window after the initial preamble transmission, M-1 beams different from the beam used for the initial preamble transmission are selected as candidate beams, and a beam is selected from the M-1 candidate beams for a retransmission. The candidate beams for the first retransmission include all available beams except the beam used for the initial preamble transmission.

[0089] In the case where the random access process is the initial transmission of the preamble code and multiple retransmissions of the preamble code, the terminal device selects a beam from the available beams for the initial transmission of the preamble code. When no RAR is received in the random access response window after the initial transmission of the preamble code, a different beam is selected from the available beams other than the beam that sent the preamble code to retransmit the preamble code once. When no RAR is received in the random access response window after the first retransmission, M-2 beams different from the beam of the initial transmission of the preamble code and the beam of the first retransmission of the preamble code are used as candidate beams, and a beam is selected from the M-2 candidate beams for the second retransmission of the preamble code. The candidate beams for the second retransmission include the available beams other than the beam of the initial transmission of the preamble code and the beam of the first retransmission of the preamble code. And so on, traversing M different beams for multiple retransmissions.

[0090] S302: The terminal device sends a preamble code.

[0091] Specifically, the terminal device may send a preamble to the network device, and the network device receives the preamble accordingly.

[0092] In the present application, the terminal device may determine the transmission power of the preamble and transmit the preamble at the determined transmission power. The transmission power of the initial transmission preamble may be a preset transmission power or a transmission power determined according to the above formula (1). After the initial transmission of the preamble, if no RAR is received in the random access response window, the terminal device selects the same transmission power as the transmission power of the initial transmission preamble to retransmit the preamble at least once.

[0093] For example, taking the case where the terminal device includes M available beams, the first M preambles including the initial transmission preamble are transmitted at the same transmission power as the transmission power of the initial transmission preamble. After the M preambles are transmitted, if the RAR is not received in the random access response window, the transmission power is increased. For example, a new transmission power is determined using the above formula (2). The preamble is transmitted from the M+1th to the 2Mth time at the new transmission power, i.e., the second round of traversing different beams to transmit the preamble is started. The transmission power of the second round of traversing different beams to transmit the preamble is higher than the transmission power of the first round of traversing different beams to transmit the preamble (i.e., the transmission power of the initial preamble). Similarly, if the RAR is still not received in the random access response window after the K*Mth transmission, the preamble is transmitted from the K*M+1th to the (K+1)*Mth time at a transmission power higher than the previous K times, where K is an integer greater than or equal to 2.

[0094] Based on the method shown in Figure 3, after the terminal device initially transmits the preamble code, if it does not receive the RAR in the random access response window, it selects a beam different from the beam of the initially transmitted preamble code to retransmit the preamble code at least once. This allows the terminal device to retransmit the preamble code by changing to a beam different from the beam of the initially transmitted preamble code when the transmission power of the initially transmitted preamble code is relatively high, thereby increasing the possibility of successful random access of the terminal device and achieving the goal of reducing the delay of random access.

[0095] In the present application, whether the transmission power of the preamble code sent this time is higher than the transmission power of the preamble code sent last time can be determined by whether the count value of the preamble power ramping counter changes. After each M-time preamble code is sent, if RAR is not received in the random access response window, the count value of the preamble power ramping counter is increased by one, and M is the number of available beams. For example, when the preamble code is sent for the Mth time, the count value of the preamble power ramping counter is 1. After the preamble code is sent for the Mth time, RAR is still not received in the random access response window. The count value of the preamble power ramping counter is increased by one, and the count value of the preamble power ramping counter is 2. When the preamble code is sent for the 2Mth time, the count value of the preamble power ramping counter is 2. After the preamble code is sent for the 2Mth time, RAR is still not received in the random access response window. The count value of the preamble power ramping counter is increased by one, and the count value of the preamble power ramping counter is 3. Similarly, if the RAR is not received in the random access response window after the K*Mth transmission, the count value of the preamble power ramp times counter is increased by one, and the count value of the preamble power ramp times counter is K.

[0096] It should be understood that the initial value of the count value of the preamble power ramp times counter when the terminal device initially transmits the preamble is not limited in this application. For example, when the terminal device initially transmits the preamble, the initial value of the count value of the preamble power ramp times counter is 1; or, when the terminal device initially transmits the preamble, the initial value of the count value of the preamble power ramp times counter is 0, without limitation.

[0097] Optionally, a preamble power ramp times counter may be pre-configured in the terminal device.

[0098] In the present application, the number of preamble transmissions can be counted by a preamble transmission counter. The count value of the preamble transmission counter is equal to the number of preamble transmissions. Each time a preamble is transmitted, the count value of the preamble transmission counter is incremented by one. For example, when the preamble is transmitted for the N-1th time, the count value of the preamble transmission counter is N-1. When the preamble is transmitted for the Nth time, the count value of the preamble transmission counter is incremented by one, and the count value of the preamble transmission counter is N.

[0099] Optionally, a preamble code sending times counter may be pre-configured in the terminal device.

[0100] Optionally, in the initial case or in the initialization state, the count value of the preamble code sending times counter is 1. When the preamble code is initially transmitted, the count value of the preamble code sending times counter is 1. After the initial transmission of the preamble code, if the RAR is not received in the random access response window, the first preamble code is retransmitted, the count value of the preamble code sending times counter is increased by one, and the count value of the preamble code sending times counter is 2. After the first preamble code is retransmitted, if the RAR is received in the random access response window, the random access is successful, and the preamble code sending times counter stops counting. If the RAR is not received in the random access response window, the second preamble code is retransmitted, the count value of the preamble code sending times counter is increased by one, and the count value of the preamble code sending times counter is 3. And so on. If the RAR is still not received in the random access response window after the K*Mth transmission, the K*M+1th preamble code is sent, the count value of the preamble code sending times counter is increased by one, and the count value of the preamble code sending times counter is K*M+1.

[0101] It should be understood that the initial value of the count value of the preamble code transmission times counter in the initial situation or in the initialized state is not limited by this application. For example, in the initial situation or in the initialized state, the initial value of the count value of the preamble code transmission times counter is 1, then when the terminal device first transmits the preamble code, the count value of the preamble code transmission times counter is 1; or, in the initial situation or in the initialized state, the initial value of the count value of the preamble code transmission times counter is 0, then when the terminal device first transmits the preamble code, the count value of the preamble code transmission times counter is 0, without limitation.

[0102] Optionally, when the terminal device is in an idle state or an inactive state, the terminal device may actively initiate a random access process and execute the method shown in Figure 3. When the terminal device is in a connected state, the terminal device may receive downlink signaling from a network device and initiate a random access process in response to the received downlink signaling, which may be a physical downlink control channel order (PDCCH order).

[0103] The PDCCH order may include the DCI format identifier (Identifier for DCI formats), Frequency Domain Resource Assignment (Frequency Domain Resource Assignment), Random Access Preamble Index (Random Access Preamble Index), Uplink / Supplementary Uplink Indicator (UL / SUL indicator), SSB Index (SS / PBCH Index), Random Access Mask Index (PRACH Mask Index), and Reserved Bits fields. The number of bits occupied by each field length is shown in Table 1. For detailed explanations of each field in Table 1, please refer to the description of 3GPP TS 38.212 V18.0.0 (2023-09) 7.3.1.2.1 Format 1_0.

[0104] Table 1

[0105] Optionally, the method for sending the preamble code in the random access process shown in Figure 3 can be pre-configured or agreed upon by a protocol, or can be indicated to the terminal device by other devices, for example, it can be indicated to the terminal device by a network device.

[0106] The method for sending a preamble in the random access process shown in FIG3 may further include the following steps before S301:

[0107] S300: The network device sends first indication information, and correspondingly, the terminal device receives the first indication information.

[0108] The first indication information is one bit and is used to indicate a method for sending a preamble during a random access process. The method for sending a preamble includes selecting a beam different from the beam used to initially transmit the preamble for at least one retransmission of the preamble if no RAR is received in the random access response window after the initial transmission of the preamble.

[0109] The network device sending the first indication information includes: the network device sending downlink signaling for triggering initiation of a random access process to the network device, and the downlink signaling includes the first indication information.

[0110] Among them, the terminal device receiving the first indication information includes: the terminal device receiving downlink signaling from the network device, the downlink signaling is used to trigger initiation of a random access process to the network device, including the first indication information.

[0111] For example, the downlink signaling sent by the network device to trigger the random access process to the network device is a 1-bit indication field of the first indication information, and the 1-bit indication field can be a newly added field with a length of 1 bit. For example, the downlink signaling can be a PDCCH order, and the downlink signaling is shown in Table 2.

[0112] Table 2

[0113] The descriptions of the DCI format identifier (Identifier for DCI formats), frequency domain resource allocation (Frequency Domain Resource Assignment), random access preamble index (Random Access Preamble index), uplink / supplementary uplink indication (UL / SUL indicator), SSB index (SS / PBCH index), and random access mask index (PRACH Mask index) fields in Table 2 are the same as the descriptions of the corresponding fields in Table 1 and are not repeated here.

[0114] The newly added field in Table 2 is 1 bit long and is used to indicate the method for sending the preamble during random access. The method for sending the preamble includes selecting a beam different from the beam used to initially transmit the preamble for at least one retransmission of the preamble if no RAR is received in the random access response window after the initial transmission of the preamble.

[0115] The Reserved bits field in Table 2 is 11 bits or 9 bits long. If used for spectrum sharing, the field is 11 bits long, otherwise it is 9 bits long.

[0116] Optionally, when the count value of the preamble code transmission counter of the terminal device reaches a preset value, in order to facilitate the upper layer to perceive the underlying situation and then adopt a reasonable communication strategy / communication measure based on the underlying situation, the random access process preamble code transmission method shown in Figure 3 may also include the following step S303:

[0117] S303: The count value of the preamble transmission times counter of the terminal device reaches a preset value, and the medium access control layer of the terminal device indicates a random access problem to the upper layer of the terminal device, or the random access process fails.

[0118] Among them, the count value of the preamble code transmission times counter of the terminal device is the value of the parameter PREAMBLE_TRANSMISSION_COUNTER used in the terminal device to determine the number of preamble code transmissions.

[0119] The preset value is the value of the parameter PREAMBLE_TRANS_MAX for the maximum number of preamble transmissions configured by the network device. Before the terminal device performs the random access process, it will obtain the preset value set by the network device through SIB2 in advance.

[0120] The media access control (MAC) layer of the terminal device is used to initiate a random access process, or to indicate a random access problem or a random access process failure to an upper layer when random access fails.

[0121] Specifically, a random access failure includes the count value of the preamble transmission count counter reaching a preset value. Therefore, when the count value of the preamble transmission count counter of the terminal device reaches the preset value, the MAC layer of the terminal device will indicate a random access problem or a random access failure to the upper layer. Whether the terminal device subsequently re-initiates the random access process is determined by the upper layer of the terminal device.

[0122] The network device in Figure 3 may include multiple devices. The following takes the network device including a traditional base station and an uplink-only TRP as an example, and the terminal device including two available beams (beam 1 and beam 2) as an example, and introduces the random access process preamble code sending method shown in Figure 3 in conjunction with Figure 4. Figure 4 is a flowchart of a random access process preamble code sending method provided by an embodiment of the present application. As shown in Figure 4, the method may include:

[0123] S400: The traditional base station sends a PDCCH command to the terminal device, and correspondingly, the terminal device receives the PDCCH command.

[0124] Among them, the traditional base station sends downlink control information (DCI) format 1_0 through the beam to trigger the PDCCH command, so that the terminal device achieves uplink synchronization with the uplink only TRP. DCI format 1_0 is often used to schedule the physical downlink shared channel (PDSCH) to the terminal device in the cell. DCI format 1_0 can be scrambled with the cyclic redundancy checksum (CRC) by the radio network temporary identifier (RNTI). RNTI is used to indicate the definition of the terminal device at different stages in the wireless cell, paging, power control sent by the network device, and system message decoding. When the terminal device decodes the CRC scrambled by DCI format 1_0 and the cell radio network temporary identifier (C-RNTI) and the "Frequency Domain Resource Assignment" field is all 1, DCI format 1_0 is used for the random access process initiated by the PDCCH command.

[0125] The PDCCH command is used to trigger the initiation of a random access procedure to an uplink-only TRP. The PDCCH command includes first indication information. The first indication information is one bit and is used to indicate the method for sending a preamble during the random access procedure. The method for sending a preamble includes selecting a beam different from the beam used for the initial preamble transmission to retransmit the preamble at least once if no RAR is received in the random access response window after the initial preamble transmission. For example, the PDCCH command includes the fields shown in Table 2, and the first indication information is a newly added one-bit field.

[0126] In one possible scenario, the first indication information occupies 1 bit in the PDCCH command, and one bit is used to indicate the method of sending the preamble code during the random access process, and whether to select a beam different from the beam of the initially transmitted preamble code for at least one retransmission of the preamble code when no RAR is received in the random access response window after the initial transmission of the preamble code. For example, binary bit 1 may indicate that, after the preamble is initially transmitted during the random access process, if no RAR is received in the random access response window, a beam different from the beam of the initially transmitted preamble is selected to retransmit the preamble at least once; binary bit 0 may indicate that, after the preamble is initially transmitted during the random access process, if no RAR is received in the random access response window, the preamble is retransmitted by increasing the transmission power of the preamble; or, for example, binary bit 0 may indicate that, after the preamble is initially transmitted during the random access process, if no RAR is received in the random access response window, the preamble is selected to retransmit the preamble at least once; binary bit 1 may indicate that, after the preamble is initially transmitted during the random access process, if no RAR is received in the random access response window, the preamble is retransmitted by increasing the transmission power of the preamble, etc., without limitation.

[0127] It should be understood that S400 is an optional execution. When a terminal device in a connected state needs to trigger a random access process to a network device through a PDCCH command, S400 is executed; when a terminal device in an idle state (idle) or a deactivated state (inactive) actively initiates a random access process to a network device, S400 is not executed.

[0128] For example, the situation in which a terminal device in an idle state or an inactive state actively initiates a random access process to a network device may include at least one of the following scenarios: (1) establishing a wireless connection during initial access: the terminal device will change from the RRC_IDLE state to the RRC_CONNECTED state; (2) an RRC connection re-establishment procedure: so that the terminal device can re-establish the wireless connection after a radio link failure. (3) handover: the terminal device needs to establish uplink synchronization with a new cell. (4) the terminal device is in the RRC_CONNECTED state, and when uplink data arrives, the uplink is in an "out-of-sync" state.

[0129] For example, a terminal device in a connected state needs a PDCCH command to trigger a random access process to a network device, including at least one of the following scenarios: (1) The terminal device is in the RRC_CONNECTED state, and when downlink data arrives, the uplink is in an "out-of-sync" state. (2) The terminal device is in the RRC_CONNECTED state, and the configuration information of the legacy base station has changed.

[0130] S401: The terminal device initially transmits a preamble to the uplink-only TRP. Correspondingly, the uplink-only TRP receives and parses the preamble.

[0131] Among them, the uplink-only TRP is a base station that supports uplink transmission but not downlink transmission.

[0132] The terminal device initially transmits a preamble to the uplink-only TRP, including: the terminal device selects a preamble from a preamble sequence. Referring to FIG5 , the terminal device selects beam 1 from two available beams and initially transmits the selected preamble to the uplink-only TRP at a transmission power of P0 for the initially transmitted preamble. Alternatively, the terminal device selects beam 1 from two available beams and initially transmits a dedicated preamble allocated by the network device to the uplink-only TRP at a transmission power of P0 for the initially transmitted preamble. At this time, the count value of the preamble power ramp-up counter is initialized to 1, and the count value of the preamble transmission count counter is initialized to 1.

[0133] Specifically, when the value of the Random Access Preamble index field in the PDCCH command is 0 or the terminal device actively initiates a random access process to the network device, the terminal device randomly selects a preamble code from the preamble code sequence, and selects beam 1 from the two available beams to initially transmit the selected preamble code to the uplink only TRP; when the value of the Random Access Preamble index field in the PDCCH command is not 0, the network device has allocated a dedicated preamble code for the terminal device, and the dedicated preamble code can be indicated by the Random Access Preamble index field in the PDCCH command. At this time, the terminal device selects beam 1 from the two available beams to initially transmit the dedicated preamble code indicated by the value of the Random Access Preamble index field in the PDCCH command to the uplink only TRP.

[0134] For example, when the terminal device actively initiates a random access process to the uplink only TRP, the terminal device randomly selects a preamble with a preamble index of 15 from the preamble sequence, and selects beam 1 to initially transmit the preamble with a preamble index of 15 to the uplink only TRP. Accordingly, the uplink only TRP receives and parses the preamble with a preamble index of 15 initially transmitted by the terminal device.

[0135] S402: After initially transmitting the preamble, the terminal device monitors the PDCCH in the random access response window to receive the RAR sent by the traditional base station.

[0136] Among them, the traditional base station refers to a base station that supports both uplink transmission and downlink transmission.

[0137] It should be understood that in the embodiment of the present application, the interaction between the uplink-only TRP and the traditional base station is ideal, that is, there is no transmission delay between the uplink-only TRP and the traditional base station.

[0138] The PDCCH carries scheduling and other control information, including transmission format, resource allocation, uplink scheduling permission power control, and uplink retransmission information.

[0139] Among them, after the terminal device initially transmits the preamble code, it monitors the PDCCH in the random access response window to receive the RAR sent by the traditional base station, including: the terminal device initially transmits the preamble code to the uplink-only TRP in beam 1 with the transmission power P0 of the initial transmission preamble code. If the uplink-only TRP receives and successfully parses the preamble code initially transmitted by the terminal device, the traditional base station will send the RAR to the terminal device, and the corresponding terminal device will receive the RAR in the random access response window after initially transmitting the preamble code; if the uplink-only TRP receives but fails to successfully parse the preamble code initially transmitted by the terminal device, the traditional base station will not send the RAR to the terminal device, and the corresponding terminal device will not receive the RAR in the random access response window after initially transmitting the preamble code, and will perform the first retransmission of the preamble code. The RAR is used to indicate the uplink resource information available to the terminal device. The RAR includes at least: the index number of the preamble code sent by the terminal device, the time adjustment information used for uplink synchronization, the dedicated uplink resource location indication information allocated to the terminal device, and the temporary C-PNTI equivalent to completing the conflict resolution.

[0140] When the terminal device actively initiates a random access process to the uplink-only TRP, the terminal device randomly selects a preamble with a preamble index of 15 from the preamble sequence, and selects beam 1 to initially transmit the preamble with a preamble index of 15 to the uplink-only TRP at the transmission power P0 of the initial transmission preamble. Furthermore, after initially transmitting the preamble with a preamble index of 15, the terminal device monitors the PDCCH in the random access response window. Accordingly, the uplink-only TRP receives but fails to successfully parse the preamble with a preamble index of 15 initially transmitted by the terminal device. The traditional base station does not send a RAR to the terminal device. Therefore, after the terminal device initially transmits the preamble with a preamble index of 15, it does not receive the RAR sent by the traditional base station in the random access response window.

[0141] S403: After initially transmitting the preamble, the terminal device does not receive the RAR in the random access response window, and selects beam 2, which is different from the beam of the initially transmitted preamble, to retransmit the preamble for the first time.

[0142] Among them, selecting beam 2 which is different from the beam of the initially transmitted preamble code for the first retransmission of the preamble code includes: the terminal device selects beam 2 from the two available beams to retransmit the preamble code to the uplink only TRP for the first time with a transmission power of P0; the transmission power of the first retransmission of the preamble code is still P0, so the count value of the preamble code power climb times counter is not counted, and the count value of the preamble code power climb times counter is still 1; the count value of the preamble code sending times counter is increased by one, and the count value of the preamble code sending times counter increases from 1 to 2.

[0143] S404: After the terminal device retransmits the preamble code for the first time, it does not receive the RAR in the random access response window, and selects beam 1 to retransmit the preamble code for the second time.

[0144] Among them, selecting beam 1 for the second retransmission of the preamble code includes: as shown in Figure 5, the terminal device selects beam 1 for the second retransmission of the preamble code; at this time, the terminal device has completed the first round of traversal of the two beams of the terminal device, and the count value of the preamble code power climb times counter is increased by one, and the count value of the preamble code power climb times counter is increased from 1 to 2, so that the transmission power of the terminal device sending the preamble code is increased to P1, and P1 is greater than P0; the count value of the preamble code sending times counter is increased by one, and the count value of the preamble code sending times counter is increased from 2 to 3.

[0145] Optionally, if the terminal device does not receive an RAR in the random access response window after retransmitting the preamble for the first time, the terminal device may refer to Figure 6 and select beam 2 for the second retransmission of the preamble. For example, if the order in which the terminal device traverses the terminal device beams in a new round is different from the order in which the terminal device traversed the terminal device beams in the first round, the terminal device selects beam 2 for the second retransmission of the preamble with reference to Figure 6. Alternatively, if the order in which the terminal device traverses the terminal device beams in a new round is the same as the order in which the terminal device traversed the terminal device beams in the first round, the terminal device will not select beam 2 for the second retransmission of the preamble with reference to Figure 6.

[0146] S405: After the terminal device retransmits the preamble code for the second time, it does not receive the RAR in the random access response window and selects beam 2 to retransmit the preamble code for the third time.

[0147] Among them, beam 2 is selected for the second retransmission of the preamble code, including: as shown in Figure 5, the terminal device selects beam 2 to retransmit the preamble code for the third time with a transmission power of P1; the count value of the preamble code power climb times counter remains unchanged, and the count value of the preamble code power climb times counter is still 2; the count value of the preamble code sending times counter is increased by one, and the count value of the preamble code sending times counter increases from 3 to 4.

[0148] Optionally, if the terminal device does not receive an RAR in the random access response window after retransmitting the preamble for the second time, the terminal device may refer to Figure 6 and select beam 1 to perform a third retransmission of the preamble with a transmit power of P1. For example, when the order in which the terminal device traverses the terminal device beams in a new round is different from the order in which the terminal device traverses the terminal device beams in the first round, the terminal device selects beam 1 to perform a third retransmission of the preamble with a transmit power of P1. Alternatively, when the order in which the terminal device traverses the terminal device beams in a new round is the same as the order in which the terminal device traverses the terminal device beams in the first round, the terminal device will not select beam 1 to perform a third retransmission of the preamble with a transmit power of P1.

[0149] S406: The count value of the preamble transmission times counter reaches the maximum number of preamble transmission times, and the MAC layer of the terminal device indicates to the upper layer that the random access process has failed, or there is a random access problem.

[0150] Among them, the maximum number of times the preamble code is sent is an alternative description of the aforementioned preset value. The maximum number of times the preamble code is sent refers to the maximum threshold value of the number of times the terminal device can send the preamble code, which is a preset value configured by the network device. The preset value is the value of PREAMBLE_TRANS_MAX configured by the network device. Before performing the random access process, the terminal device will obtain the maximum number of times the preamble code is sent set by the network device through SIB2 in advance.

[0151] The count value of the preamble transmission times counter reaches the maximum preamble transmission times, which can be alternatively described as the count value of the preamble transmission times counter is greater than or equal to the maximum preamble transmission times.

[0152] S406 is an optional execution. When the maximum number of preamble transmissions configured by the network device is 4, and the terminal device does not receive RAR in the random access response window after retransmitting the preamble for the third time, S406 is executed; when the maximum number of preamble transmissions configured by the network device is a natural number greater than 4, or when the terminal device receives RAR in the random access response window after retransmitting the preamble for the third time, S406 is not executed.

[0153] Based on the method shown in Figure 4, in a communication system including a terminal device, a traditional base station, and an uplink-only TRP, and in the case of ideal interaction between the traditional base station and the uplink-only TRP, the terminal device selects a beam different from the beam of the initially transmitted preamble code to retransmit the preamble code at least once if the RAR is not received in the random access response window after the initial transmission of the preamble code. This fully utilizes the characteristic that the uplink path loss between the terminal device and the uplink-only TRP is smaller than the downlink path loss between the traditional base station and the terminal device, maximizes the utilization of the transmission power of the initially transmitted preamble code of the terminal device, and preferentially retransmits the preamble code in a beam different from the beam of the initially transmitted preamble code after the initial transmission of the preamble code, thereby increasing the possibility of successful random access of the terminal device and achieving the goal of reducing the random access delay.

[0154] The above mainly introduces the solution provided by the embodiment of the present application from the perspective of interaction between various devices. It is understandable that each device, such as network equipment (such as traditional base stations), terminal equipment, etc., in order to realize the above functions, includes a hardware structure and / or software module corresponding to the execution of each function. Those skilled in the art should easily appreciate that, in conjunction with the algorithm steps of each example described in the embodiments disclosed herein, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in a hardware or computer software driven hardware manner depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0155] In the embodiments of the present application, network devices, terminal devices, etc. can be grouped into functional modules according to the above-mentioned method examples. For example, each functional module can be grouped according to each function, or two or more functions can be integrated into one processing module. The above-mentioned integrated modules can be implemented in the form of hardware or in the form of software functional modules. It should be noted that the grouping of modules in the embodiments of the present application is schematic and is only a logical functional grouping. In actual implementation, other grouping methods may be used.

[0156] Figure 7 shows a structural diagram of a communication device 700, which can be used to perform the functions of the terminal device involved in the above embodiments. As an implementation method, the communication device 700 shown in Figure 7 includes: a processing unit 7001, a transceiver unit 7002;

[0157] The processing unit 7001 is configured to select a beam for sending a preamble during a random access process; the random access process includes at least an initial transmission of a preamble, and at least one retransmission of the preamble after the initial transmission of the preamble if no RAR is received in the random access response window; and selecting a beam different from the beam of the initially transmitted preamble to retransmit the preamble at least once if no RAR is received in the random access response window after the initial transmission of the preamble; for example, the processing unit 7001 may support the communication device 700 in executing S401 to S403.

[0158] The transceiver unit 7002 is configured to send a preamble; for example, the transceiver unit 7002 may be configured to support the communication device 700 in executing S401 and S403.

[0159] For the description of the random access process, random access response window, initial transmission of the preamble, and at least one retransmission of the preamble, reference may be made to that in the above method embodiment.

[0160] Specifically, all relevant contents of each step involved in the method embodiment shown in FIG4 can be referred to the functional description of the corresponding functional module and will not be repeated here. The communication device 700 is used to perform the functions of the terminal device in the random access process preamble code transmission method shown in FIG4, and thus can achieve the same effect as the random access process preamble code transmission method described above.

[0161] As another possible implementation, the communication device 700 shown in FIG7 includes: a processing module and a communication module. The processing module is used to control and manage the operations of the communication device 700. For example, the processing module may integrate the functions of the processing unit 7001 and may be used to support the communication device 700 in executing S401 to S403 and other processes of the technology described herein. The communication module may integrate the functions of the transceiver unit 7002 and may be used to support the communication device 700 in executing S401 and S403 and communicating with other network entities, such as communication with the functional modules or network entities shown in FIG4. The communication device 700 may also include a storage module for storing program code and data of the communication device 700.

[0162] FIG8 shows a structural diagram of a communication device 800, which can be used to perform the functions of the network device involved in the above embodiments. As an implementation method, the communication device 800 shown in FIG8 includes: a transceiver unit 8001;

[0163] The transceiver unit 8001 is configured to send first indication information, where the first indication information is used to indicate a method for sending a preamble during a random access process. For example, the transceiver unit 8001 may be configured to support the communication apparatus 800 in executing S400.

[0164] Among them, the relevant descriptions of the first indication information, the random access process, and the method of sending the preamble code can refer to those in the above method embodiment.

[0165] Specifically, all relevant content of each step involved in the method embodiment shown in Figure 4 can be referenced to the functional description of the corresponding functional module and will not be repeated here. The communication device 800 is used to perform the functions of the network device in the random access process preamble code transmission method shown in Figure 4, and thus can achieve the same effect as the random access process preamble code transmission method described above.

[0166] As another possible implementation, the communication device 800 shown in FIG8 includes a communication module and a processing module. The communication module may integrate the functions of the transceiver unit 8001 and may be used to support the communication device 800 in executing S400 and communicating with other network entities, such as communication with the functional modules or network entities shown in FIG4 . The processing module is used to control and manage the operations of the communication device 800. The communication device 800 may also include a storage module for storing program code and data of the communication device 800.

[0167] As mentioned above, the processing module may be a processor or a controller. It may implement or execute the various exemplary logic blocks, modules and circuits described in conjunction with the disclosure of this application. The processor may also be a combination that implements computing functions, such as a combination of one or more microprocessors, a combination of a DSP and a microprocessor, and so on. The communication module may be a transceiver circuit or a communication interface, and so on. The storage module may be a memory. When the processing module is a processor, the communication module is a communication interface, and the storage module is a memory, the communication device 700 and the communication device 800 involved in the embodiment of the present application may be the communication device 900 shown in Figure 9. For example, the terminal equipment and network equipment mentioned above may adopt the composition structure shown in Figure 9 or include the components shown in Figure 9. Figure 9 is a schematic diagram of the composition of a communication device 900 provided in an embodiment of the present application. As shown in Figure 9, the communication device 900 may include a processor 9001, a communication line 9002 and a communication interface 9003.

[0168] Furthermore, the communication device 900 may further include a memory 9004 . The processor 9001 , the memory 9004 and the communication interface 9003 may be connected via a communication line 9002 .

[0169] The processor 9001 may be a central processing unit (CPU), a general-purpose processor, a network processor (NP), a digital signal processor (DSP), a microprocessor, a microcontroller, a programmable logic device (PLD), or any combination thereof. The processor 9001 may also be other communication devices with processing capabilities, such as circuits, devices, or software modules.

[0170] The communication line 9002 is used to transmit information between the components included in the communication device 900.

[0171] The communication interface 9003 is used to communicate with other devices or other communication networks. The other communication network can be Ethernet, a radio access network (RAN), a wireless local area network (WLAN), etc. The communication interface 9003 can be a radio frequency module, a transceiver, or any communication device capable of achieving communication. The embodiment of the present application is described using the communication interface 9003 as an example of a radio frequency module, wherein the radio frequency module may include an antenna, a radio frequency circuit, etc., and the radio frequency circuit may include a radio frequency integrated chip, a power amplifier, etc.

[0172] The memory 9004 is used to store instructions, where the instructions may be computer programs.

[0173] Among them, the memory 9004 can be a read-only memory (ROM) or other types of static storage devices that can store static information and / or instructions, or a random access memory (RAM) or other types of dynamic storage devices that can store information and / or instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage, magnetic disk storage media or other magnetic storage devices, and optical disc storage includes compact discs, laser discs, optical discs, digital versatile discs, Blu-ray discs, etc.

[0174] It should be noted that the memory 9004 can exist independently of the processor 9001 or can be integrated with the processor 9001. The memory 9004 can be used to store instructions, program code, or some data. The memory 9004 can be located within the communication device 900 or outside the communication device 900, without limitation. The processor 9001 is configured to execute the instructions stored in the memory 9004 to implement the random access procedure preamble transmission method provided in the following embodiments of the present application.

[0175] In an example, the processor 9001 may include one or more CPUs, such as CPU0 and CPU1 in FIG. 9 .

[0176] As an optional implementation, the communication device 900 includes multiple processors. For example, in addition to the processor 9001 in FIG. 9 , it may also include a processor 9007 .

[0177] As an optional implementation, the communication device 900 further includes an output device 9005 and an input device 9006. The input device 9006 is a keyboard, a mouse, a microphone, or a joystick, and the output device 9005 is a display screen, a speaker, or other devices.

[0178] It should be noted that the communication device 900 may be a desktop computer, a portable computer, a network server, a mobile phone, a tablet computer, a wireless terminal, an embedded device, a chip system, or a device having a structure similar to that shown in FIG9 . Furthermore, the component structure shown in FIG9 does not limit the communication device. In addition to the components shown in FIG9 , the communication device may include more or fewer components than shown, or combine certain components, or arrange the components differently.

[0179] In the embodiment of the present application, the chip system can be composed of chips, or can include chips and other discrete devices.

[0180] The embodiments of the present application also provide a computer-readable storage medium. All or part of the processes in the above-mentioned method embodiments can be completed by a computer program to instruct the relevant hardware. The program can be stored in the above-mentioned computer-readable storage medium. When the program is executed, it can include the processes of the above-mentioned method embodiments. The computer-readable storage medium can be a terminal device of any of the above-mentioned embodiments, such as: an internal storage unit including a data transmission end and / or a data receiving end, such as a hard disk or memory of the terminal device. The above-mentioned computer-readable storage medium can also be an external storage device of the above-mentioned terminal device, such as a plug-in hard disk, a smart memory card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the above-mentioned terminal device. Furthermore, the above-mentioned computer-readable storage medium can also include both the internal storage unit of the above-mentioned terminal device and an external storage device. The above-mentioned computer-readable storage medium is used to store the above-mentioned computer program and other programs and data required by the above-mentioned terminal device. The above-mentioned computer-readable storage medium can also be used to temporarily store data that has been output or is to be output.

[0181] It should be understood that the collection, storage, use, processing, transmission, provision, and disclosure of user personal information involved in the technical solution of this application complies with relevant laws and regulations and does not violate public order and good morals. For example, in the technical solution of this application, the processing of user personal information is carried out with the user's authorization, and the same description is not repeated here.

[0182] It should be noted that the terms "first" and "second" in the specification, claims, and drawings of this application are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units that are not listed, or may optionally include other steps or units that are inherent to these processes, methods, products, or devices.

[0183] It should be understood that in the present application, "at least one (item)" refers to one or more, "more than one" refers to two or more, "at least two (items)" refers to two or three and more than three, and "and / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0184] It should be understood that in the embodiments of the present application, "B corresponding to A" means that B is associated with A. For example, B can be determined based on A. It should also be understood that determining B based on A does not mean determining B based solely on A; B can also be determined based on A and / or other information. In addition, the "connection" in the embodiments of the present application refers to various connection methods, such as direct connection and indirect connection, to achieve communication between devices, and the embodiments of the present application do not impose any limitations on this.

[0185] Unless otherwise specified, the "transmission" (transmit / transmission) appearing in the embodiments of the present application refers to bidirectional transmission, including the actions of sending and / or receiving. Specifically, the "transmission" in the embodiments of the present application includes the sending of data, the receiving of data, or the sending of data and the receiving of data. In other words, the data transmission here includes uplink and / or downlink data transmission. Data may include channels and / or signals, uplink data transmission is uplink channel and / or uplink signal transmission, and downlink data transmission is downlink channel and / or downlink signal transmission. The "network" and "system" appearing in the embodiments of the present application express the same concept, and the communication system is the communication network.

[0186] Through the description of the above implementation methods, technical personnel in the relevant field can clearly understand that for the convenience and simplicity of description, only the grouping of the above-mentioned functional modules is used as an example. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be grouped into different functional modules to complete all or part of the functions described above.

[0187] In the several embodiments provided in this application, it should be understood that the disclosed communication devices and methods can be implemented in other ways. For example, the communication device embodiments described above are merely illustrative. For example, the grouping of the modules or units is merely a logical functional grouping. In actual implementation, there may be other grouping methods, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be through some interface, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0188] The units described as separate components may or may not be physically separate, and the components shown as units may be one physical unit or multiple physical units, that is, they may be located in one place or distributed in multiple different places. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0189] In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0190] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on this understanding, the technical solution of the embodiment of the present application is essentially 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, which is stored in a storage medium and includes several instructions for enabling a device, such as a single-chip microcomputer, a chip, etc., or a processor to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media for storing program codes, such as a USB flash drive, a mobile hard disk, a ROM, a RAM, a magnetic disk, or an optical disk.

[0191] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for sending a preamble in a random access procedure, characterized in that, Comprising: Selecting a beam for transmitting a preamble during a random access procedure; Transmitting the preamble; The random access procedure at least includes an initial transmission of the preamble, and at least one retransmission of the preamble if a random access response RAR is not received within a random access response window after the initial transmission of the preamble; If a RAR is not received within a random access response window after the initial transmission of the preamble, selecting a beam different from the beam used for the initial transmission of the preamble for at least one retransmission of the preamble.

2. The method according to claim 1, wherein: The beams used for the first N-1 transmissions of the preamble are not used as candidate beams for the Nth transmission of the preamble, where N is an integer greater than 1, N≤M, and M is the number of available beams.

3. The method according to any one of claims 1-2, wherein: If, after the Mth transmission of the preamble during a random access procedure, a RAR is still not received within a random access response window, then the (M+1)th transmission of the preamble is performed, and the candidate beams for the (M+1)th transmission include M beams, and the beams used for the first N-M-1 transmissions of the preamble are not used as candidate beams for the Nth transmission of the preamble, where M<N≤2M and M is the number of available beams.

4. The method according to any one of claims 1-3, wherein: The number of preamble power ramps is counted by a preamble power ramp counter; The number of preamble power ramps being counted by a preamble power ramp counter includes: after the Mth integer multiple of transmissions of the preamble, if a RAR is still not received within a random access response window, then the count value of the preamble power ramp counter is incremented by one, where M is the number of available beams.

5. The method according to any one of claims 1-4, wherein: The number of preamble transmissions is counted by a preamble transmission counter; The number of preamble transmissions being counted by a preamble transmission counter includes: if a RAR is not received within a random access response window after the preamble is transmitted, then the count value of the preamble transmission counter is incremented by one.

6. The method according to any one of claims 1-5, characterized in that, The method is executed by a terminal device, and further includes: If the count value of the preamble transmission counter reaches a preset value, the medium access control layer of the terminal device indicates a random access problem to the upper layer of the terminal device, or indicates that the random access procedure has failed.

7. The method according to claim 1, wherein The method further includes: Receiving first indication information for indicating a manner of transmitting the preamble during a random access procedure.

8. The method according to claim 7, wherein: The manner of transmitting the preamble includes selecting a beam different from the beam used for the initial transmission of the preamble for at least one retransmission of the preamble if a RAR is not received within a random access response window after the initial transmission of the preamble.

9. The method according to claim 7, wherein The receiving of the first indication information includes: Receiving a downlink signaling from a network device, the downlink signaling being used to trigger initiating a random access procedure to the network device, and the downlink signaling including the first indication information.

10. The method according to claim 7 or 8, characterized in that the first indication information is a one-bit indication field.

11. A method for sending a preamble in a random access process, characterized in that, comprising: sending first indication information, the first indication information being used to indicate a manner of sending the preamble in a random access procedure.

12. The method according to claim 11, characterized in that the manner of sending the preamble includes, in a case where a random access response (RAR) is not received in a random access response window after an initial transmission of the preamble, selecting at least one beam different from the beam used for the initial transmission of the preamble for retransmission of the preamble.

13. The method according to claim 11, characterized in that The sending of the first indication information includes: sending a downlink signaling, the downlink signaling being used to trigger the initiation of a random access procedure to the network device, and the downlink signaling including the first indication information.

14. The method according to claim 11 or 13, characterized in that the first indication information is a one-bit indication field.

15. A communication device, characterized in that, The communication device is applied to a terminal device, and the communication device includes: a processing unit, configured to select a beam for sending a preamble in a random access procedure; a transceiver unit, configured to send the preamble; wherein the random access procedure at least includes an initial transmission of the preamble, and retransmission of the preamble in a case where a random access response (RAR) is not received in a random access response window after the initial transmission of the preamble; in a case where a random access response (RAR) is not received in a random access response window after the initial transmission of the preamble, selecting at least one beam different from the beam used for the initial transmission of the preamble for retransmission of the preamble.

16. A communication device, characterized in that, The communication device includes a processor and a communication interface, and the processor and the communication interface are used to support the communication device to execute the method for sending a preamble in a random access procedure according to any one of claims 1-10.

17. A communication device, characterized in that, The communication device is applied to a network device, and the communication device includes: a transceiver unit, configured to send first indication information, the first indication information indicating a manner of sending a preamble in a random access procedure.

18. A communication device, characterized in that, The communication device includes a processor and a communication interface, and the processor and the communication interface are used to support the communication device to execute the method for sending a preamble in a random access procedure according to any one of claims 11-14.

19. A communication system, characterized in that, The communication system includes the communication device according to claim 15 or 16, or the communication system includes the communication device according to claim 17 or 18.

20. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions, and when the computer instructions run on a computer, the computer is caused to execute the method according to any one of claims 1-10, or the computer is caused to execute the method according to any one of claims 11-14.

21. A computer program product, characterized in that, The computer program product includes computer instructions, and when the computer instructions run on a computer, the computer is caused to execute the method according to any one of claims 1-10, or the computer is caused to execute the method according to any one of claims 11-14.

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