COMMUNICATION METHOD, COMMUNICATION DEVICE, AND COMMUNICATION SYSTEM

Abstract

[0010] An embodiment of the present application provides a communication method, a communication device, and a communication system. The communication method includes: a second communication device determines first time information, where the first time information is obtained through calculation based on a first transmission delay and a second transmission delay, where the first transmission delay is a transmission delay from the first communication device to the second communication device, and the second transmission delay is a transmission delay from the first communication device to a third communication device, the second communication device is a communication device corresponding to the first cell, and the third communication device is a communication device corresponding to the second cell; the second communication device sends a first message, and in response, the first communication device receives the first message; and the first communication device determines a first timing advance (TA) value of the second cell based on the first time information. [0011] According to the embodiment of the present application, it is possible to avoid service interruptions caused by obtaining a TA value in a random access process.

Description

[Technical Field]

[0001] The present application relates to the field of communication technologies, and in particular to communication methods, communication devices, and communication systems. [Background technology]

[0002] In a mobile communication system, a terminal device may switch between different network devices. In the process of the terminal device switching from a source network device to a target network device, after disconnecting from the source network device, the terminal device may access the target network device in a random access manner and establish a connection to the target network device for data communication.

[0003] Generally, a terminal device may perform uplink timing synchronization with a target network device in a random access process. For example, the terminal device may send a random access preamble to the target network device. The target network device calibrates an uplink timing advance (TA) value based on the random access preamble and sends the TA value to the terminal device via a timing advance command. The terminal device performs uplink data transmission with the target network device based on the TA value to implement uplink timing synchronization between the terminal device and the target network device.

[0004] However, in the method in which the terminal device obtains the TA value through random access, the terminal device is disconnected from the source network device and then takes a long time to establish a connection to the target network device, resulting in a long-term service interruption for the terminal device. Summary of the Invention

[0005] The embodiments of the present application disclose a communication method, a communication device, and a communication system that avoid service interruptions caused by obtaining a TA value in a random access process.

[0006] According to a first aspect, an embodiment of the present application provides a communication method. The method may be performed by a first communication device, or may be performed by a component (e.g., a chip or a circuit) of the first communication device, which is not limited herein. The method includes:

[0007] The first communication device receives a first message from a second communication device, wherein the first message includes first time information, the first time information being determined based on a first transmission delay and a second transmission delay, the first transmission delay being a transmission delay from the first communication device to the second communication device, the second transmission delay being a transmission delay from the first communication device to a third communication device, the second communication device being a communication device corresponding to the first cell, and the third communication device being a communication device corresponding to the second cell; the first communication device determines a first timing advance (TA) value of the second cell based on the first time information; and the first communication device sends uplink data to the third communication device based on the first TA value.

[0008] In this embodiment of the present application, the first cell may be a source cell on which the first communication device camps, and the second cell may be a target cell to which the first communication device will switch. The first TA value indicates an opportunity for the first communication device to send uplink data to the third communication device. The second communication device may determine first time information based on the first transmission delay and the second transmission delay, and indicate the first TA value of the second cell by including the first time information in the first message. The first communication device may determine the first TA value based on the first time information, and does not need to determine the TA value of the second cell in the random access process, thereby avoiding service interruption caused by obtaining the TA value of the second cell in the random access process and reducing the interruption duration of the first communication device in the process of switching from the second communication device to the third communication device.

[0009] In a possible implementation, the first time information indicates a first TA value, the first TA value being determined based on a second TA value and a first time difference, the second TA value being the TA value of the first cell or the TA value of a first timing advance group (TAG) of the first communication device, and the first time difference being the difference between the first transmission delay and the second transmission delay.

[0010] In this embodiment of the present application, the second TA value is a TA value used when the first communication device performs uplink data transmission with the second communication device. The first time information indicating the first TA value may specifically mean that the first time information includes the first TA value or includes information used to determine the first TA value, for example, the first time difference. If the first time information includes the first TA value, the first TA value may be obtained by the second communication device through calculation based on the second TA value and the first time difference and then sent to the first communication device through the first message, and the first communication device may directly obtain the first TA value from the first time information. If the first time information includes information used to determine the first TA value, the first communication device may obtain the first TA value through calculation based on the second TA value and the first time difference. The first TA value is obtained through calculation based on the second TA value and the first time difference, so that the obtained first TA value can more accurately indicate the opportunity for the first communication device to send uplink data.

[0011] In a possible implementation, the step of the first communication device determining a first timing advance TA value of the first cell based on the first time information comprises:

[0012] The first communication device determines a first TA value based on the first time information and the second TA value, where the second TA value is the TA value of the first cell or the TA value of the first TAG of the first communication device.

[0013] In this embodiment of the present application, the second TA value is a TA value used when the first communication device performs uplink data transmission with the second communication device. The first communication device may obtain the first TA value through calculation based on the first time information and the second TA value, thereby making the obtained first TA value more accurate.

[0014] In a possible implementation, the first message further includes first indication information, and the first indication information indicates the first TAG.

[0015] In a possible implementation, the first time information includes a first time difference, the first time difference being a difference between the first transmission delay and the second transmission delay, and the step of the first communication device determining the first TA value based on the first time information and the second TA value includes:

[0016] The first communication device determines a first TA value based on the first time difference and the second TA value.

[0017] In this embodiment of the present application, the first time difference may alternatively be understood as the difference between the time when the first reference signal sent by the first communication device is transmitted to the second communication device and the time when the first reference signal is transmitted to the third communication device, and the first TA value may be understood as the round-trip transmission delay from the first communication device to the third communication device. The first TA value is determined based on the second TA value and the difference between the first transmission delay and the second transmission delay, so that the accuracy of the obtained first TA value may be higher.

[0018] In a possible implementation, the first time information further includes a first downlink timing offset, where the first downlink timing offset is a downlink timing offset between the first cell and the second cell, and the step of the first communication device determining the first TA value based on the first time difference and the second TA value includes:

[0019] The first communication device determines a first TA value based on the first time difference, the second TA value, and the first downlink timing offset.

[0020] In this embodiment of the present application, the first downlink timing offset can be understood as the difference between the subframe boundaries that are closest in the time domain and belong to the first cell and the second cell. When the downlink timing of the first cell is not synchronized with the downlink timing of the second cell, the first TA value is further related to the first downlink timing offset. The first communication device obtains the first TA value through calculation based on the first time difference, the first downlink timing offset, and the second TA value, so that the accuracy of the obtained first TA value can be higher.

[0021] In a possible implementation, the first TA value satisfies TA1=TA2-2*(UL_TDOA-Δ), where TA1 is the first TA value, TA2 is the second TA value, UL_TDOA is the first time difference, and Δ is the first downlink timing offset.

[0022] In a possible implementation, the method further comprises:

[0023] The first communication device determines the downlink frame timing of the second cell based on the first time difference and the first downlink frame timing, where the first downlink frame timing is the downlink frame timing of the first cell or the downlink frame timing of the first TAG.

[0024] In this embodiment of the present application, the downlink frame timing of the second cell indicates an opportunity for the first communication device to receive downlink data sent by the third communication device, and the first downlink frame timing indicates an opportunity for the first communication device to receive downlink data sent by the second communication device. The first communication device may determine the downlink frame timing of the second cell based on the first time difference and the first downlink frame timing, so that the first communication device can perform downlink data transmission with the third communication device based on the downlink frame timing of the second cell to implement downlink timing synchronization between the first communication device and the third communication device.

[0025] In a possible implementation, the downlink frame timing of the second cell is obtained by adjusting the first downlink frame timing forward or backward by the first time difference.

[0026] In a possible implementation, the first time information includes a second time difference, the second time difference being a difference between a round-trip transmission delay from the first communication device to the second communication device and a round-trip transmission delay from the first communication device to the third communication device, and the step of the first communication device determining the first TA value based on the first time information and the second TA value includes:

[0027] The first communication device determines a first TA value based on the second time difference and the second TA value.

[0028] In this embodiment of the present application, the first TA value can be understood as a round-trip transmission delay from the first communication device to the third communication device, and the second TA value can be understood as a round-trip transmission delay from the first communication device to the second communication device. The first communication device obtains the first TA value through calculation based on the second time difference and the second TA value, so that the obtained first TA value can be more accurate.

[0029] In a possible implementation, the second time difference is determined based on the first time difference and a first downlink timing offset, where the first time difference is the difference between the first transmission delay and the second transmission delay, and the first downlink timing offset is the downlink timing offset between the first cell and the second cell.

[0030] In this embodiment of the present application, when the downlink timing of the first cell is not synchronized with the downlink timing of the second cell, the second time difference is related to the first downlink timing offset, and the second communication device may obtain the second time difference through calculation based on the first time difference and the first downlink timing offset, so that the obtained second time difference is more accurate.

[0031] In a possible implementation, the first TA value satisfies TA1=TA2-TA_offset, where TA1 is the first TA value, TA2 is the second TA value, and TA_offset is the second time difference.

[0032] According to a second aspect, an embodiment of the present application provides a communication method. The method may be performed by a second communication device, or may be performed by a component (e.g., a chip or circuit) of the second communication device, which is not limited herein. The method includes:

[0033] The second communication device determines first time information, where the first time information is determined based on a first transmission delay and a second transmission delay, where the first transmission delay is a transmission delay from the first communication device to the second communication device, and the second transmission delay is a transmission delay from the first communication device to a third communication device, where the second communication device is a communication device corresponding to the first cell, and the third communication device is a communication device corresponding to the second cell; and the second communication device sends a first message to the first communication device, where the first message includes the first time information.

[0034] In this embodiment of the present application, the first time information indicates a TA value of the second cell. The second communication device may determine the first time information based on the first transmission delay and the second transmission delay, and send the first time information to the first communication device through a first message, so that the first communication device can determine the first TA value based on the first time information to avoid service interruption caused by the first communication device obtaining the first TA value in the random access process.

[0035] In a possible implementation, the first time information indicates a first TA value, the first TA value being determined based on a second TA value and a first time difference, the first TA value being the TA value of the second cell, the second TA value being the TA value of the first cell or the TA value of a first timing advance group TAG of the first communication device, and the first time difference being the difference between the first transmission delay and the second transmission delay.

[0036] In this embodiment of the present application, the second TA value is a TA value used when the first communication device performs uplink data transmission with the second communication device. The first time information indicating the first TA value may specifically mean that the first time information includes the first TA value or includes information used to determine the first TA value, for example, the first time difference. If the first time information includes the first TA value, the first TA value may be obtained by the second communication device through calculation based on the second TA value and the first time difference and then sent to the first communication device through the first message, and the first communication device may directly obtain the first TA value from the first time information. If the first time information includes information used to determine the first TA value, the first communication device may obtain the first TA value through calculation based on the second TA value and the first time difference. The first TA value is obtained through calculation based on the second TA value and the first time difference, so that the obtained first TA value can more accurately indicate the opportunity for the first communication device to send uplink data.

[0037] In a possible implementation, the first time information includes a first time difference, the first time difference being a difference between the first transmission delay and the second transmission delay.

[0038] In this embodiment of the present application, the second communication device may send the first time difference to the first communication device via the first time information, so that the first communication device can determine the first TA value based on the first time difference.

[0039] In a possible implementation, the first time information further includes a first downlink timing offset, where the first downlink timing offset is a downlink timing offset between the first cell and the second cell.

[0040] In this embodiment of the present application, the second communication device may send the first time difference and the first downlink timing offset to the first communication device via the first time information, so that the first communication device can obtain the first TA value through calculation based on the first time difference and the first downlink timing offset.

[0041] In a possible implementation, the first time information includes a second time difference, the second time difference being the difference between a round-trip transmission delay from the first communication device to the second communication device and a round-trip transmission delay from the first communication device to the third communication device, the second time difference being determined based on the first time difference, and the first time difference being the difference between the first transmission delay and the second transmission delay.

[0042] In this embodiment of the present application, the second communication device may send the second time difference to the first communication device via the first time information, so that the first communication device can determine the first TA value based on the second time difference.

[0043] In a possible implementation, the second time difference is determined based on the first time difference and a first downlink timing offset, where the first downlink timing offset is a downlink timing offset between the first cell and the second cell.

[0044] In this embodiment of the present application, when the downlink timing of the first cell is not synchronized with the downlink timing of the second cell, the second time difference is related to the first downlink timing offset, and the second communication device may determine the second time difference based on the first time difference and the first downlink timing offset, so that the accuracy of the obtained second time difference may be higher.

[0045] In a possible implementation, the method further comprises:

[0046] The second communication device receives a second message from the fourth communication device, where the second message indicates the first time information.

[0047] The step of the second communication device determining the first time information comprises:

[0048] The second communication device determines the first time information based on the second message.

[0049] In this embodiment of the present application, the second message may include one or more of a first time difference, a first downlink timing offset, a first downlink timing, and a first receiving time point. The second communication device may be a distributed unit, and the fourth communication device may be a central unit corresponding to the second communication device. The second communication device may determine the first time information based on the second message, so that the first communication device can determine a first TA value based on the first time information to avoid service interruption caused by obtaining the first TA value in the random access process.

[0050] In a possible implementation, the second message includes a first downlink timing offset, and the step of the second communication device determining the first time information based on the second message includes:

[0051] The second communication device determines first time information based on the first downlink timing offset.

[0052] In this embodiment of the present application, the second communication device may obtain a first downlink timing offset through interaction with the fourth communication device, and determine first time information based on the first downlink timing offset, so that the first time information can indicate a first TA value, and the first communication device can determine the first TA value based on the first time information to avoid service interruption caused by obtaining the first TA value in the random access process.

[0053] In a possible implementation, the method further comprises:

[0054] The second communication device sends a fourth message to the fourth communication device, where the fourth message includes a second downlink timing, and the second downlink timing is the downlink timing of the first cell.

[0055] In this embodiment of the present application, the second communication device may report the downlink timing of the first cell to the fourth communication device, so that the fourth communication device can determine the first downlink timing offset based on the downlink timing of the first cell.

[0056] In a possible implementation, the second message includes a first downlink timing, the first downlink timing being a downlink timing of the second cell, and the method further comprises:

[0057] The second communication device determines a first downlink timing offset based on the first downlink timing and the second downlink timing, where the second downlink timing is the downlink timing of the first cell.

[0058] The step of determining, by the second communication device, the first time information based on the second message includes:

[0059] The second communication device determines first time information based on the first downlink timing offset.

[0060] In this embodiment of the present application, the second communication device may obtain the downlink timing of the second cell through interaction with the fourth communication device, determine a first downlink timing offset based on the downlink timing of the first cell and the downlink timing of the second cell, and determine first time information based on the first downlink timing offset, so that the first time information can indicate a first TA value, and the first communication device can determine the first TA value based on the first time information to avoid service interruption caused by obtaining the first TA value in the random access process.

[0061] In a possible implementation, the first downlink timing includes a time corresponding to a radio frame, a time corresponding to a subframe, or a time corresponding to a slot.

[0062] In a possible implementation, the second message includes a first time difference, and the step of determining the first time information by the second communication device based on the second message includes:

[0063] The second communication device determines first time information based on the first time difference.

[0064] In this embodiment of the present application, the second communication device may obtain a first time difference through interaction with the fourth communication device, and determine first time information based on the first time difference, so that the first time information can indicate a first TA value, and the first communication device can determine the first TA value based on the first time information to avoid service interruptions caused by obtaining the first TA value in the random access process.

[0065] In a possible implementation, the method further comprises:

[0066] the second communication device receives a first reference signal from the first communication device; The second communication device sends a third message to the fourth communication device, where the third message includes a second reception time, and the second reception time is the time when the second communication device receives the first reference signal.

[0067] In this embodiment of the present application, the second receiving time point is the time point when the second communication device receives the first reference signal, i.e., the second receiving time point is the time point when the first reference signal is transmitted to the second communication device. After receiving the first reference signal transmitted by the first communication device, the second communication device may record the second receiving time point and transmit the second receiving time point to the fourth communication device through a third message, so that the fourth communication device can determine the first time difference based on the second receiving time point.

[0068] In a possible implementation, the second message includes a first receiving time point, the first receiving time point being a time point at which the first reference signal of the first communication device is transmitted to the third communication device, and the method further comprises:

[0069] The second communication device determines a first time difference based on the first reception time point and the second reception time point, where the second reception time point is the time point at which the second communication device receives the first reference signal.

[0070] The step of determining, by the second communication device, the first time information based on the second message includes:

[0071] The second communication device determines first time information based on the first time difference.

[0072] In this embodiment of the present application, the first receiving time point is the time point when the first reference signal is transmitted to the third communication device, i.e., the first receiving time point is the time point when the third communication device receives the first reference signal. The second communication device may obtain the first receiving time point through interaction with the fourth communication device, and determine a first time difference based on the first receiving time point and the second receiving time point, and can further determine first time information based on the first time difference, so that the first time information can indicate a first TA value. The first communication device can determine the first TA value based on the first time information to avoid service interruption caused by obtaining the first TA value in the random access process.

[0073] In a possible implementation, the method further comprises:

[0074] The second communication device sends a first request message to a fourth communication device, where the first request message is used to request to obtain the second message.

[0075] According to a third aspect, an embodiment of the present application provides a communication method. The method may be performed by a fourth communication device, or may be performed by a component (e.g., a chip or circuit) of the fourth communication device, which is not limited herein. The method includes:

[0076] The fourth communication device receives a fifth message from the third communication device, where the fifth message includes a first receiving time point or a first downlink timing, where the first receiving time point is the time point when the third communication device receives a first reference signal sent by the first communication device, where the first downlink timing is the downlink timing of a second cell, and the third communication device is a communication device corresponding to the second cell; the fourth communication device sends a second message to the second communication device based on the first receiving time point or the first downlink timing, where the second message indicates first time information, where the first time information is determined based on a first transmission delay and a second transmission delay, where the first transmission delay is a transmission delay from the first communication device to the second communication device, and the second transmission delay is a transmission delay from the first communication device to the third communication device, and the second communication device is a communication device corresponding to the first cell.

[0077] In this embodiment of the present application, the fourth communication device may obtain the first receiving time point or the first downlink timing through interaction with the third communication device, and send a second message based on the first downlink timing and the first receiving time point, so that the second communication device can determine the first time information based on the second message.

[0078] In a possible implementation, the fifth message includes a first receiving time point, the second message includes a first time difference, the first time difference being a difference between the first transmission delay and the second transmission delay, and the method further comprises:

[0079] The fourth communication device receives a third message from the second communication device, where the third message includes a second reception time point, the second reception time point being the time point at which the second communication device receives the first reference signal; and the fourth communication device determines a first time difference based on the first reception time point and the second reception time point.

[0080] In this embodiment of the present application, the first time difference may be a difference between the first receiving time point and the second receiving time point, and the fourth communication device determines the first time difference based on the first receiving time point and the second receiving time point, and sends the first time difference to the second communication device via a second message, so that the second communication device can determine the first time information based on the first time difference.

[0081] In a possible implementation, the fifth message includes a first downlink timing, the second message includes a first downlink timing offset, the first downlink timing offset being a downlink timing offset between the first cell and the second cell, and the method further comprises:

[0082] The fourth communication device receives a fourth message from the second communication device, where the fourth message includes a second downlink timing, and the second downlink timing is the downlink timing of the first cell; and the fourth communication device determines a first downlink timing offset based on the first downlink timing and the second downlink timing.

[0083] In this embodiment of the present application, the fourth communication device determines a first downlink timing offset based on the first downlink timing and the second downlink timing, and sends the first downlink timing offset to the second communication device via a second message, so that the second communication device can determine the first time information based on the first downlink timing offset.

[0084] In a possible implementation, the second message includes the first reception time or the first downlink timing.

[0085] In this embodiment of the present application, the fourth communication device may send the first reception time point or the first downlink timing to the second communication device via a second message, so that the second communication device can determine the first time information based on the first reception time point or the first downlink timing.

[0086] In a possible implementation, the method further comprises:

[0087] The fourth communication device receives a first request message from the second communication device, where the first request message is used to request to obtain a second message.

[0088] In this embodiment of the present application, the second message may include one or more of a first time difference, a first downlink timing offset, a first downlink timing, and a first reception time point, and the first request message is used to request one or more of the first time difference, the first downlink timing offset, the first downlink timing, and the first reception time point. Upon receiving the first request message, the fourth communication device may send corresponding information to the second communication device via the second message, so that the second communication device can determine the first time information based on the second message. Alternatively, the second communication device may indicate an opportunity for the fourth communication device to send the second message via the first request message, thereby improving interaction efficiency between the second communication device and the fourth communication device.

[0089] In a possible implementation, the method further comprises:

[0090] The fourth communication device sends a second request message to the third communication device, where the second request message is used to request to acquire the first receiving time point or the first downlink timing.

[0091] In this embodiment of the present application, the fourth communication device may send a second request message to the third communication device to obtain the first receiving time point or the first downlink timing, so that the fourth communication device can determine the second message based on the first receiving time point or the first downlink timing.

[0092] According to a fourth aspect, an embodiment of the present application provides a communication method. The method may be performed by a third communication device, or may be performed by a component (e.g., a chip or circuit) of the third communication device, which is not limited herein. The method includes:

[0093] The third communication device receives a second request message from the fourth communication device, where the second request message is used to request a first receiving time point or a first downlink timing, where the first receiving time point is the time point when the third communication device receives a first reference signal from the first communication device, where the first downlink timing is the downlink timing of a second cell, and the third communication device is a communication device corresponding to the second cell; the third communication device sends a fifth message to the fourth communication device, where the fifth message includes the first receiving time point or the first downlink timing.

[0094] In this embodiment of the present application, the third communication device may send the first receiving time point or the first downlink timing to the fourth communication device via a fifth message, so that the fourth communication device can send a second message based on the first receiving time point or the first downlink timing, where the second message indicates the first time information.

[0095] In a possible implementation, the method further comprises:

[0096] The third communication device receives the first reference signal.

[0097] In this embodiment of the present application, the third communication device may receive the first reference signal sent by the first communication device, record the first reception time point at which the first reference signal is received, and determine the first reception time point.

[0098] According to a fifth aspect, an embodiment of the present application provides a communication device configured to perform the method of the first aspect or any one of its possible implementations, the communication device comprising a unit configured to perform the method of the first aspect or any one of its possible implementations.

[0099] According to a sixth aspect, an embodiment of the present application provides a communication device configured to perform the method of the second aspect or any one of its possible implementations, the communication device comprising a unit configured to perform the method of the second aspect or any one of its possible implementations.

[0100] According to a seventh aspect, an embodiment of the present application provides a communication device configured to perform the method of the third aspect or any one of its possible implementations, the communication device comprising a unit configured to perform the method of the third aspect or any one of its possible implementations.

[0101] According to an eighth aspect, an embodiment of the present application provides a communication device configured to perform the method of the fourth aspect or any one of its possible implementations, the communication device comprising a unit configured to perform the method of the fourth aspect or any one of its possible implementations.

[0102] According to a ninth aspect, an embodiment of the present application provides a communication device. The communication device includes a processor configured to execute the method of the first aspect or any one of its possible implementations. Alternatively, the processor is configured to execute a program stored in a memory. When the program is executed, the method of the first aspect or any one of its possible implementations is performed.

[0103] In a possible implementation, the memory is located external to the communication device.

[0104] In a possible implementation, the memory is located in the communication device.

[0105] In this embodiment of the present application, the processor and the memory may alternatively be integrated into one component, in other words, the processor and the memory may alternatively be integrated together.

[0106] In a possible implementation, the communication device further comprises a transceiver, the transceiver being configured to receive or send signals.

[0107] According to a tenth aspect, an embodiment of the present application provides a communication device, the communication device comprising a processor configured to execute the method of the second aspect or any one of its possible implementations. Alternatively, the processor is configured to execute a program stored in a memory. When the program is executed, the method of the second aspect or any one of its possible implementations is performed.

[0108] In a possible implementation, the memory is located external to the communication device.

[0109] In a possible implementation, the memory is located in the communication device.

[0110] In this embodiment of the present application, the processor and the memory may alternatively be integrated into one component, in other words, the processor and the memory may alternatively be integrated together.

[0111] In a possible implementation, the communication device further comprises a transceiver, the transceiver being configured to receive or send signals.

[0112] According to an eleventh aspect, an embodiment of the present application provides a communication device. The communication device includes a processor configured to execute the method of the third aspect or any one of its possible implementations. Alternatively, the processor is configured to execute a program stored in a memory. When the program is executed, the method of the third aspect or any one of its possible implementations is performed.

[0113] In a possible implementation, the memory is located external to the communication device.

[0114] In a possible implementation, the memory is located in the communication device.

[0115] In this embodiment of the present application, the processor and the memory may alternatively be integrated into one component, in other words, the processor and the memory may alternatively be integrated together.

[0116] In a possible implementation, the communication device further comprises a transceiver, the transceiver being configured to receive or send signals.

[0117] According to a twelfth aspect, an embodiment of the present application provides a communication device. The communication device includes a processor configured to execute the method of the fourth aspect or any one of its possible implementations. Alternatively, the processor is configured to execute a program stored in a memory. When the program is executed, the method of the fourth aspect or any one of its possible implementations is performed.

[0118] In a possible implementation, the memory is located external to the communication device.

[0119] In a possible implementation, the memory is located in the communication device.

[0120] In this embodiment of the present application, the processor and the memory may alternatively be integrated into one component, in other words, the processor and the memory may alternatively be integrated together.

[0121] In a possible implementation, the communication device further comprises a transceiver, the transceiver being configured to receive or send signals.

[0122] According to a thirteenth aspect, an embodiment of the present application provides a communication device, comprising: a logic circuit and an interface, the logic circuit coupled to the interface, the interface configured to input a first message and output uplink data, and the logic circuit configured to determine a first TA value.

[0123] It can be understood that the description of the first message and the first TA value should refer to the method in the first aspect or any one of the possible implementations, and the details will not be described again in this specification.

[0124] According to a fourteenth aspect, an embodiment of the present application provides a communication device, the communication device comprising: a logic circuit and an interface, the logic circuit being coupled to the interface, the logic circuit being configured to determine first time information, and the interface being configured to output a first message.

[0125] It can be understood that the description of the first time information and the first message should refer to the method in the second aspect or any one of the possible implementations, and the details will not be described again in this specification.

[0126] According to a fifteenth aspect, an embodiment of the present application provides a communication device, the communication device comprising: a logic circuit and an interface, the logic circuit being coupled to the interface, the interface being configured to input a fifth message and output a second message.

[0127] It can be understood that the description of the fifth message and the second message should refer to the method in the third aspect or any one of the possible implementations, and the details will not be described again in this specification.

[0128] According to a sixteenth aspect, an embodiment of the present application provides a communication device, the communication device comprising: a logic circuit and an interface, the logic circuit being coupled to the interface, the interface being configured to input the second request message and output the fifth message.

[0129] It can be understood that the description of the second request message and the fifth message should refer to the method in the fourth aspect or any one of the possible implementations, and the details will not be described again in this specification.

[0130] According to a seventeenth aspect, an embodiment of the present application provides a computer-readable storage medium configured to store a computer program, which, when executed on a computer, is enabled to perform the method of the first aspect or any one of possible implementations of the first aspect, the method of the second aspect or any one of possible implementations of the second aspect, the method of the third aspect or any one of possible implementations of the third aspect, or the method of the fourth aspect or any one of possible implementations of the fourth aspect.

[0131] According to an eighteenth aspect, an embodiment of the present application provides a computer program product, the computer program product comprising a computer program or computer code, which, when run on a computer, is enabled to perform the method of the first aspect or any one of its possible implementations, the method of the second aspect or any one of its possible implementations, the method of the third aspect or any one of its possible implementations, or the method of the fourth aspect or any one of its possible implementations.

[0132] According to a nineteenth aspect, an embodiment of the present application provides a communication system, the communication system including at least one of the following, but not limited to, a first communication device, a second communication device, a third communication device, and a fourth communication device, wherein the first communication device is configured to perform the method of the first aspect or any one of its possible implementations, the second communication device is configured to perform the method of the second aspect or any one of its possible implementations, the fourth communication device is configured to perform the method of the third aspect or any one of its possible implementations, and the third communication device is configured to perform the method of the fourth aspect or any one of its possible implementations. [Brief explanation of the drawings]

[0133] The following describes the accompanying drawings used in the embodiments of the present application.

[0134] [Figure 1] 1 is a diagram of the structure of a communication system according to an embodiment of the present application; [Figure 2A] FIG. 1 is a diagram of the structure of a communication system in an intra-CU scenario according to an embodiment of the present application. [Figure 2B]FIG. 1 is a diagram of the structure of a communication system in an inter-CU scenario according to an embodiment of the present application. [Figure 3] FIG. 1 is a diagram of a handover procedure according to an embodiment of the present application. [Figure 4] FIG. 1 is a diagram of a random access procedure according to an embodiment of the present application. [Figure 5] FIG. 1 is an interaction diagram of a communication method according to an embodiment of the present application. [Figure 6] FIG. 2 is a diagram of a relationship between a first TA value and a second TA value according to an embodiment of the present application. [Figure 7] 4 is an interaction flowchart of another communication method according to an embodiment of the present application; [Figure 8] 10 is an interaction flowchart of yet another communication method according to an embodiment of the present application; [Figure 9] 10 is an interaction flowchart of yet another communication method according to an embodiment of the present application; [Figure 10] 10 is an interaction flowchart of yet another communication method according to an embodiment of the present application; [Figure 11] 10 is an interaction flowchart of yet another communication method according to an embodiment of the present application; [Figure 12] 10 is an interaction flowchart of yet another communication method according to an embodiment of the present application; [Figure 13] 10 is an interaction flowchart of yet another communication method according to an embodiment of the present application; [Figure 14] 10 is an interaction flowchart of yet another communication method according to an embodiment of the present application; [Figure 15] 10 is an interaction flowchart of yet another communication method according to an embodiment of the present application; [Figure 16] 1 is a diagram of the structure of a communication device according to an embodiment of the present application; [Figure 17] 1 is a diagram of the structure of a communication device according to an embodiment of the present application; [Figure 18] 1 is a diagram of the structure of a communication device according to an embodiment of the present application; DETAILED DESCRIPTION OF THE INVENTION

[0135] In the specification, claims, and accompanying drawings of this application, the terms "first," "second," and the like are intended only to distinguish between different objects and do not limit the sequence, chronology, priority, or importance of multiple objects. In the embodiments of this application, "multiple" refers to two or more. In addition, the terms "comprise" and "have," and any derivatives thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or device comprising a series of steps or units is not limited to the enumerated steps or units, but may optionally further include steps or units not enumerated, or may optionally further include other steps or units inherent to the process, method, product, or device. In addition, the character " / " generally indicates an "or" relationship between associated objects.

[0136] The term "embodiment" as used herein means that a specific feature, structure, or characteristic described with reference to the embodiment may be included in at least one embodiment of the present application. Phrases appearing in various places in the present specification do not necessarily refer to the same embodiment, and are not an independent or optional embodiment that is exclusive of another embodiment. Those skilled in the art may explicitly and implicitly understand that the embodiments described herein may be combined with other embodiments.

[0137] A terminal device in an embodiment of the present application may be a terminal that accesses a communication system and has wireless transceiver functionality, or a chip or chip system that may be disposed within the terminal. The terminal device may also be referred to as user equipment (UE), access terminal, subscriber unit, subscriber station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent, or user equipment. The terminal device may be a device that provides voice and / or data connectivity to a user, or may include a device capable of performing sidelink communication, such as an in-vehicle terminal or a handheld terminal capable of performing vehicle-to-everything (V2X) communication. For example, the terminal device may alternatively be a mobile phone, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a handheld device with wireless communication capabilities, a computing device, another processing device connected to a wireless modem, an in-vehicle device, a wearable device, a terminal device in a future 5G network, a terminal device in a future evolved public land mobile network (PLMN), or the like, but this is not limited to the embodiments of the present application.

[0138] The network device in the embodiment of the present application may be a network device that accesses a communication system and has a wireless transceiver function, or a chip or chip system that may be disposed in the network device. The network device may be a device that connects a terminal device to a wireless network, and specifically may be a base station. Various types of base stations may be included, such as a macro base station, a micro base station (also called a small cell), a relay station, and an access point. The base station may specifically be an access point (AP) in a wireless local area network (WLAN), a base transceiver station (BTS) in a global system for mobile communications (GSM) or code division multiple access (CDMA), a NodeB (NB) in wideband code division multiple access (WCDMA), an Evolved NodeB (eNB or eNodeB) in LTE, a relay station, an access point, an in-vehicle device, or a wearable device, a next generation NodeB (gNB) in a 5G system, a base station in a future evolved public land mobile network (PLMN), or the like. In one possible manner, the network device may be a base station (e.g., gNB) having an architecture in which a central unit (CU) and a distributed unit (DU) are separated.

[0139] Figure 1 is an example of a communication system according to an embodiment of the present application. As shown in Figure 1, the communication system may include at least one network device and at least one terminal device. In Figure 1, two network devices and one terminal device are used as an example. The two network devices are a first network device and a second network device, respectively. The terminal device may be connected to the first network device through a Uu interface.

[0140] In a possible implementation, the first network device and the second network device may be base stations in a CU-DU split architecture. For example, the first network device may include CU1 and DU1, and the second network device may include CU2 and DU2. For example, the first network device and the second network device may use the same CU but different DUs. In other words, CU1 and CU2 may be the same CU. As shown in FIG. 2A, DU1 and DU2 may be deployed under the same CU, and a terminal device is connected to DU1. For example, the terminal device camps on the first cell of DU1.

[0141] Optionally, the first network device and the second network device may use different CUs and different DUs. As shown in FIG. 2B, DU1 is deployed under CU1, and DU2 is deployed under C U2 lower and a terminal device is connected to DU1.

[0142] For example, in a communication system, a terminal device is mobile, and each network device has a limited coverage area. Therefore, the terminal device may switch between different network devices in a movement process. For example, the terminal device may switch between a first network device and a second network device. For example, the terminal device may switch from a first cell of DU1 to a second cell of DU2. For example, a procedure in which the terminal device switches from the first network device to the second network device is shown in Figure 3. The steps in Figure 3 are described below. 301: A terminal device reports a measurement report to a first network device. For example, the first network device performs a measurement configuration for the terminal device, and the terminal device performs measurement and reporting based on the measurement configuration of the first network device. 302: The first network device makes a handover decision based on the measurement report. For example, the first network device determines whether the terminal device needs to be handed over based on the measurement report, and determines a target network device (e.g., a second network device) for the handover. 303: The first network device sends a handover request message to the second network device. When the first network device determines that the terminal device needs to be handed over to the second network device, the first network device sends a handover request message to the second network device. 304: The second network device performs access control, for example, the second network device determines whether to allow the terminal device access based on the number of connections, load, or other status of the second network device. 305: The second network device returns a Handover Request Acknowledgement message to the first network device. 306: The first network device sends a radio resource control (RRC) reconfiguration message to the terminal device, and in response, the terminal device receives the RRC reconfiguration message. After receiving the RRC reconfiguration message, the terminal device disconnects from the first network device and accesses the second network device in a random access process. 307: The first network device performs data forwarding. 308: The terminal device sends an RRC reconfiguration complete message to the second network device to complete the handover process.

[0143] 3, when a terminal device is disconnected from a first network device and establishes a connection to a second network device for data communication, the terminal device needs to perform downlink timing synchronization and uplink timing synchronization with the second network device. The downlink timing synchronization (downlink radio frame, subframe, slot, symbol boundary, and corresponding index number) is implemented by the terminal device by searching for a downlink reference signal (e.g., synchronization signal block (SSB)) sent by the second network device, and the uplink timing synchronization is implemented by the terminal device in a random access process.

[0144] For example, the second network device may instruct the terminal device to perform contention-based random access (CBRA) or contention-free random access (CFRA). The CBRA procedure performed by the terminal device is shown in Figure 4. The terminal device performing CBRA may include the following steps: 401: A terminal device sends a random access preamble to a second network device, where the random access preamble is used to request random access to the second network device. The second network device may estimate a transmission delay between the second network device and the terminal device based on the random access preamble, so that the second network device can calibrate an uplink timing advance (TA) value and notify the terminal device of the calibration information through a timing advance command. 402: The terminal device receives a random access response (RAR) message sent by a second network device. For example, the terminal device may monitor a physical downlink control channel (PDCCH) by using a random access radio network temporary identifier (RA-RNTI) to receive the RAR message sent by the second network device. The RAR message includes a timing advance command, an uplink grant (UL grant) assigned in message 3 (Msg3), a temporary cell radio network temporary identifier (C-RNTI) assigned by the second network device, and the like. The terminal device may adjust the uplink timing by using the timing advance value in the timing advance command in the RAR message. 403: The terminal device sends a message (Msg3) based on the scheduling transmission to the second network device. 404: The terminal device receives a conflict resolution message (Msg4) sent by the second network device.

[0145] In the handover process shown in Figure 4, the terminal device acquires the TA value of the target cell to which the terminal device will switch through a random access channel (RACH) to implement uplink timing synchronization between the terminal device and the second network device. However, in the manner of acquiring the TA value through the RACH, the terminal device is disconnected from the first network device and then takes a long time to establish a connection to the second network device, resulting in a long-term service interruption for the terminal device and affecting the service experience.

[0146] In view of this, the embodiments of the present application provide a communication method, a communication device, and a communication system that avoid service interruptions caused by obtaining a TA value in a random access process.

[0147] 5 is an interaction diagram of a communication method according to an embodiment of the present application. The communication method shown in FIG. 5 may be applied to the communication system shown in FIG. 1, 2A, or 2B. Alternatively, the method may be applied to a first communication device and a second communication device. The first communication device may be the terminal device described above, and the second communication device may be the network device described above or a DU in a split architecture. As shown in FIG. 5, the communication method includes, but is not limited to, the following steps: 501: A second communication device determines first time information, where the first time information is determined based on a first transmission delay and a second transmission delay, the first transmission delay is a transmission delay from the first communication device to the second communication device, the second transmission delay is a transmission delay from the first communication device to a third communication device, the second communication device is a communication device corresponding to the first cell, and the third communication device is a communication device corresponding to the second cell.

[0148] For example, the first time information indicates a first TA value, where the first TA value is the TA value of the second cell, and the first TA value is determined based on the second TA value and a first time difference, where the second TA value is the TA value of the first cell or the TA value of a first timing advance group (TAG) of the first communication device, and the first time difference is the difference between the first transmission delay and the second transmission delay.

[0149] For example, the second communication device may assign at least one TAG to the first communication device, the first TAG being one of the at least one TAG.

[0150] For example, the first cell may be a source cell that the first communication device camps on before performing cell switching, and the second cell may be a target cell to which the first communication device will switch.

[0151] For example, the second communication device may determine the first time information based on an interaction with the third communication device or the fourth communication device. For example, if the second communication device is the network device described above, the second communication device may determine the first time information based on an interaction with the third communication device. As another example, if the second communication device is a DU in a split architecture, the second communication device may determine the first time information based on an interaction with the fourth communication device. The second communication device may be a DU corresponding to the first cell, and the fourth communication device may be a CU corresponding to the DU.

[0152] For example, the second communication device may determine the first time information after making a handover decision based on a measurement report reported by the first communication device. Alternatively, the second communication device may determine the first time information after receiving a handover request acknowledgement message. This is not a limitation in the present application. 502: A second communication device sends a first message, and in response, a first communication device receives a first message, where the first message includes first time information.

[0153] For example, the first message may be a handover command or may be included in a handover command, which instructs the first communication device to switch from the first cell to the second cell. In other words, the second communication device may include first time information in the handover command, so that the first communication device can determine the first TA value based on the first time information.

[0154] For example, after receiving the first message, the first communication device switches from the first cell to the second cell. 503: The first communication device determines, based on the first time information, a first TA value of the second cell.

[0155] For example, the first time information indicates a first TA value, and the first TA value indicates an opportunity for the first communication device to send uplink data to the third communication device. The first communication device may determine a TA value to be used when the first communication device switches to the second cell based on the first time information.

[0156] In a possible implementation, the first time information includes a first TA value, and the first communication device may directly obtain the first TA value from the first time information. In other words, the first communication device determines the TA value held in the first time information as the TA value of the second cell.

[0157] In another possible implementation, the first communication device determines a first TA value based on the first time information and a second TA value, where the second TA value is the TA value of the first cell or the TA value of the first TAG of the first communication device.

[0158] For example, the first TAG is a TAG of the first communication device. The first time information is related to a first time difference, and the first time difference is a difference between the first transmission delay and the second transmission delay.

[0159] For example, the first message may further include first instruction information, where the first instruction information indicates a first TAG, i.e., the second TA value is the TA value of the TAG indicated by the first instruction information. The second communication device may assign at least one TAG to the first communication device and indicate the first TAG in the at least one TAG through the first instruction information, so that the first communication device can determine the first TA value based on the TA value of the first TAG and the first time information. For example, the first instruction information may include an index of the first TAG. 504: The first communication device sends uplink data to the third communication device based on the first TA value.

[0160] For example, the first communication device may send uplink data to the third communication device in advance with a first TA value to implement uplink timing synchronization.

[0161] In this embodiment of the present application, the first cell may be a source cell on which the first communication device camps, and the second cell may be a target cell to which the first communication device will switch. The first TA value indicates an opportunity for the first communication device to send uplink data to the third communication device. The second communication device may obtain first time information based on the first transmission delay and the second transmission delay, and indicate the first TA value of the second cell by including the first time information in the first message. The first communication device may determine the first TA value based on the first time information, and does not need to determine the TA value of the second cell in the random access process, thereby avoiding service interruption caused by obtaining the TA value of the second cell in the random access process and reducing the interruption duration of the first communication device in the process of switching from the second communication device to the third communication device.

[0162] In this application, a method in which the first communication device does not acquire a TA value through a RACH in the handover process may be referred to as a random access-less handover (RACH-less handover, RACH-less HO). It may be understood that the second communication device and the third communication device may or may not be deployed in the same location. In other words, the deployment of the second communication device and the third communication device is not limited in this application. Therefore, this application has a universal application scenario.

[0163] To describe the first time information in more detail, this embodiment of the present application further provides the following several implementations.

[0164] Implementation 1: The first time information includes a first TA value, the first TA value is determined based on a second TA value and a first time difference, the first TA value is the TA value of the second cell, the second TA value is the TA value of the first cell or the TA value of the first TAG, and the first time difference is the difference between the first transmission delay and the second transmission delay.

[0165] In this implementation, the first communication device may directly obtain the TA value of the second cell from the first time information, i.e., the first communication device determines the first TA value included in the first time information as the TA value of the second cell.

[0166] The second communication device may determine a first TA value based on the second TA value and the first time difference.

[0167] For example, the first TA value satisfies the following formula: TA1=TA2-2*UL_TDOA (1) TA1 is the first TA value, TA2 is the second TA value, and UL_TDOA is the first time difference.

[0168] For example, the second communication device may obtain the first TA value through calculation based on Equation (1). It may be understood that in some implementations, the value of the first TA value may not be equal to TA2-2*UL_TDOA. For example, the value of the first TA value may be within a first value range, which includes TA2-2*UL_TDOA, i.e., the first TA value is approximately equal to TA2-2*UL_TDOA. For example, the first value range may be a range centered around TA2-2*UL_TDOA. For example, the first value range may range from x% of TA2-2*UL_TDOA to y% of TA2-2*UL_TDOA, where x is less than 100 and y is greater than 100. For example, the first value range may range from 95% of TA2-2*UL_TDOA to 105% of TA2-2*UL_TDOA. It may be understood that the specific values ​​of x and y may be determined in a specific implementation process.

[0169] In a possible implementation, the second communication device may determine a first TA value based on the second TA value, the first time difference, and the first downlink timing offset, where the first downlink timing offset is a downlink timing offset between the first cell and the second cell.

[0170] For example, if the downlink timing of the first cell is not synchronized with the downlink timing of the second cell, the second communication device may determine the first TA value based on the second TA value, the first time difference, and the first downlink timing offset. The downlink timing offset between the first cell and the second cell may be understood as the difference between the two nearest subframe boundaries of the first cell and the second cell in the time domain.

[0171] For example, as shown in FIG. 6, the difference between the two nearest subframe boundaries of the first cell and the second cell in the time domain is Δ, i.e., the first downlink timing Gusset is Δ, the distance from the first communication device to the second communication device and the distance from the first communication device to the third communication device are d1 and d2, respectively, the signal propagation speed is c, and the first time difference satisfies the following formula: UL_TDOA=(d1-d2) / c+Δ (2) UL_TDOA is the first time difference.

[0172] For example, the first TA value satisfies the following formula: TA1=TA2-2*(UL TDOA -Δ) (3) TA1 is the first TA value, TA2 is the second TA value, UL_TDOA is the first time difference, and Δ is the first downlink timing offset.

[0173] The second communication device may obtain the first TA value through calculation based on equation (3). In some implementations, the first TA value is TA2-2*(UL TDOA It can be appreciated that the value of the first TA value may not be equal to TA2-2*(UL −Δ). For example, the value of the first TA value may be within a second range of values, and the second range of values ​​may be TA2-2*(UL −Δ). TDOA -Δ), or the value of the first TA value is approximately TA2-2*(UL TDOA -Δ). For example, Second The value range is TA2-2*(UL TDOA -Δ) may be in the range centered around

[0174] For example, the derivation process of equation (3) may be as follows:

[0175] TA1=TA2-[(d1-d2) / c+Δ]-[(d1-d2) / c-Δ]=TA2-2*(d1-d2) / c=TA1-2*(UL_TDOA-Δ) In this implementation, the first time information includes a first TA value, and the first communication device can directly obtain the first TA value from the first time information, so that the first communication device can quickly determine the first TA value. The second communication device may obtain the first TA value through calculation based on the first time difference, the second TA value, and the first downlink timing offset, so that the obtained first TA value can more accurately indicate the opportunity for the first communication device to send uplink data, that is, the obtained first TA value has higher accuracy.

[0176] Implementation 2: The first time information includes a first time difference, and the first time difference is a difference between the first transmission delay and the second transmission delay.

[0177] In this implementation, the first communication device may determine a first TA value based on a first time difference and a second TA value, where the first time difference may be understood as the difference between the arrival time of the first reference signal sent by the first communication device and received by the second communication device and the arrival time of the first reference signal sent by the first communication device and received by the third communication device.

[0178] In a possible implementation, the second TA value is the TA value of the second cell. If the downlink timing of the first cell is synchronized with the downlink timing of the second cell, i.e., the subframe boundaries of the first cell and the second cell in the time domain are the same, the second communication device may include a first time difference in the first time information, and the first communication device determines the first TA value based on the first time difference and the second TA value.

[0179] For example, the first communication device may determine the first TA value based on equation (1).

[0180] In a possible implementation, the first communication device may determine the downlink frame timing of the second cell based on the first time difference and the first downlink frame timing, where the first downlink frame timing is the downlink frame timing of the first cell or the downlink frame timing of the first TAG.

[0181] For example, the downlink frame timing of the first cell indicates an opportunity for the first communication device to receive downlink data of the first cell, the downlink frame timing of the first TAG indicates an opportunity for the first communication device to receive downlink data of the carrier in the first TAG, and the downlink frame timing of the second cell indicates an opportunity for the first communication device to receive downlink data of the second cell. The first communication device may determine the downlink frame timing of the second cell based on the first time information and the first downlink frame timing, so that the first communication device can perform downlink data transmission with the third communication device based on the downlink frame timing of the second cell to implement downlink timing synchronization between the first communication device and the third communication device.

[0182] In some implementations, the downlink frame timing of the second cell is obtained by adjusting the first downlink frame timing by a first time difference. For example, the first communication device may adjust the first downlink frame timing forward or backward by the first time difference to obtain the downlink frame timing of the second cell. For example, if the first distance is smaller than the second distance, the downlink frame timing of the second cell is obtained by adjusting the first downlink frame timing backward by the first time difference. The first distance is the distance from the first communication device to the second communication device, and the second distance is the distance from the first communication device to the third communication device. As another example, if the first distance is larger than the second distance, the downlink frame timing of the second cell is obtained by adjusting the first downlink frame timing forward by the first time difference.

[0183] In a possible implementation, the first message further includes a first value, where the first value indicates a difference between radio frame numbers corresponding to two nearest subframe boundaries of the first cell and the second cell in the time domain and / or a difference between the subframe numbers corresponding to the two subframe boundaries. For example, when the radio frame numbers and / or the subframe numbers corresponding to the two subframe boundaries corresponding to the first downlink timing offset are different, the second communication device may indicate the difference between the radio frame numbers corresponding to the two subframe boundaries and / or the difference between the subframe numbers corresponding to the two subframe boundaries by using the first value, so that the first communication device can determine the downlink frame timing of the second cell and the downlink subframe numbers of the second cell based on the first message.

[0184] In this implementation, the first communication device may determine the first TA value based on the first time difference and the second TA value, which may result in a higher accuracy of the obtained first TA value.

[0185] Implementation 3: The first time information includes a first time difference and a first downlink timing offset.

[0186] In this implementation, the first communication device may determine the first TA value based on the first time difference, the second TA value, and the first downlink timing offset. For example, if the downlink timing of the first cell is not synchronized with the downlink timing of the second cell, the second communication device may include the first time difference and the first downlink timing offset in the first time information, and the first communication device determines the first TA value based on the first time difference, the second TA value, and the first downlink timing offset.

[0187] For example, the first communication device may determine the first TA value based on equation (3).

[0188] In a possible implementation, the first communication device may determine the downlink frame timing of the second cell based on the first time difference, the first downlink frame timing, and the first downlink timing offset, where the first downlink frame timing is the downlink frame timing of the first cell or the downlink frame timing of the first TAG.

[0189] For example, the first communication device adjusts the first downlink frame timing forward or backward by a third time difference to obtain the downlink frame timing of the second cell, where the third time difference is determined based on the first time difference and the first downlink timing offset. For example, if the first distance is smaller than the second distance, the downlink frame timing of the second cell is obtained by adjusting the first downlink frame timing backward by the third time difference. As another example, if the first distance is larger than the second distance, the downlink frame timing of the second cell is obtained by adjusting the first downlink frame timing forward by the third time difference.

[0190] For example, the third time difference satisfies the following formula: T=UL TDOA -2*Δ (4) T is the third time difference, UL_TDOA is the first time difference, and Δ is the first downlink timing offset.

[0191] In a possible implementation, the first message further includes a first value, where the first value indicates a difference between radio frame numbers corresponding to two nearest subframe boundaries of the first cell and the second cell in the time domain and / or a difference between the subframe numbers corresponding to the two subframe boundaries. For example, when the radio frame numbers and / or the subframe numbers corresponding to the two subframe boundaries corresponding to the first downlink timing offset are different, the second communication device may indicate the difference between the radio frame numbers corresponding to the two subframe boundaries and / or the difference between the subframe numbers corresponding to the two subframe boundaries by using the first value, so that the first communication device can determine the downlink frame timing of the second cell and the downlink subframe numbers of the second cell based on the first message.

[0192] In this implementation, when the downlink timing of the first cell is not synchronized with the downlink timing of the second cell, the first TA value is further related to a first downlink timing offset, and the first communication device obtains the first TA value through calculation based on the first time difference, the first downlink timing offset, and the second TA value, so that the obtained first TA value may be more accurate.

[0193] Implementation 4: The first time information includes a second time difference, and the second time difference is the difference between a round-trip transmission delay from the first communication device to the second communication device and a round-trip transmission delay from the first communication device to the third communication device.

[0194] In this implementation, the first communication device determines the first TA value based on the second time difference and the second TA value, where the second time difference may be obtained through calculation based on the first time difference.

[0195] For example, the second time difference may be twice the difference between the arrival time of the first reference signal sent by the first communication device and received by the second communication device and the arrival time of the first reference signal sent by the first communication device and received by the third communication device, i.e., the second time difference may satisfy the following formula: TA offset =2*UL_TDOA (5) TA_offset is the second time difference, and UL_TDOA is the first time difference.

[0196] The second communication device may obtain the second time difference through calculation based on equation (5).

[0197] In a possible implementation, the second time difference may be obtained based on the first time difference and the first downlink timing offset. For example, the second time difference may satisfy the following formula: TA_offset=2*(UL TDOA -Δ) (6) TA_offset is the second time difference, UL_TDOA is the first time difference, and Δ is the first downlink timing offset.

[0198] For example, if the downlink timing of the first cell is not synchronized with the downlink timing of the second cell, the second communication device may obtain the second time difference through calculation based on Equation (6). In this embodiment of the present application, if the downlink timing of the first cell is not synchronized with the downlink timing of the second cell, the second time difference is related to the first downlink timing offset. The second communication device may obtain the second time difference through calculation based on the first time difference and the first downlink timing offset, thereby making the obtained second time difference more accurate.

[0199] In some implementations, the first TA value may be the sum of the second TA value and the second time difference, i.e., the first TA value satisfies the following formula: TA1=TA2+TA_offset (7) TA1 is the first TA value, TA2 is the second TA value, and TA_offset is the second time difference.

[0200] For example, if the first distance is smaller than the second distance, the first communication device may obtain the first TA value through calculation based on equation (7).

[0201] In some other implementations, the first TA value is between the second TA value and the second time value. With an offset of That is, the first TA value satisfies the following formula: TA1=TA2-TA_offset (8) TA1 is the first TA value, TA2 is the second TA value, and TA_offset is the second time difference.

[0202] For example, if the first distance is greater than the second distance, the first communication device may obtain the first TA value through calculation based on equation (8).

[0203] In this implementation, the first communication device obtains the first TA value through calculation based on the second time difference and the second TA value, which may result in higher accuracy of the obtained first TA value.

[0204] 7 is an interaction diagram of another communication method according to an embodiment of the present application. The method shown in FIG. 7 may be applied to the communication system shown in FIG. 2A. Alternatively, the method may be applied to a first communication device, a second communication device, a third communication device, and a fourth communication device. The first communication device may be the terminal device described above, the second communication device may be a DU in a split architecture, the third communication device may be a network device described above (e.g., a base station in a CU-DU split architecture), and the fourth communication device may be a CU corresponding to the second communication device. As shown in FIG. 7, the method includes, but is not limited to, the following steps:

[0205] In some possible implementations, the method shown in FIG. 701: A second communication device sends a first request message, and in response, a fourth communication device receives the first request message, where the first request message is used to request to acquire a second message, and the second message indicates first time information.

[0206] For example, the first request message may be used to request one or more of a first time difference, a first downlink timing offset, a first downlink timing, and a first reception time point. The first reception time point is a time point at which the third communication device receives a first reference signal sent by the first communication device, the first downlink timing is a downlink timing of a second cell, and the third communication device is a communication device corresponding to the second cell. For example, the downlink timing of the second cell indicates a time point corresponding to a system frame boundary, a subframe boundary, or a slot boundary of the second cell.

[0207] For example, after making a handover decision based on the measurement report reported by the first communication device, the second communication device may obtain the second message and thereby send a first request message to the fourth communication device requesting that the first time information be determined based on the second message. Alternatively, the second communication device may determine when to send the first request message to the fourth communication device.

[0208] In some possible implementations, the first request message may indicate an opportunity for the fourth communication device to send the second message. For example, the first request message may indicate that the fourth communication device should immediately feedback the second message after receiving the first request message. As another example, the first request message may indicate that the fourth communication device should feedback the second message within a certain period of time after receiving the first request message. As another example, the first request message may indicate a specific moment for the fourth communication device to send the second message. In this implementation, the second communication device may indicate an opportunity for the fourth communication device to send the second message via the first request message, thereby improving interaction efficiency between the second communication device and the fourth communication device.

[0209] In some implementations, the method shown in FIG. 702: The fourth communication device sends a second request message, and in response, the third communication device receives the second request message, where the second request message is used to request a first receiving time point or a first downlink timing.

[0210] It may be understood that the fourth communication device may send the second request message to the third communication device after receiving the first request message. Alternatively, the fourth communication device may send the second request message to the third communication device before receiving the second request message. This is not a limitation in the present application.

[0211] In some implementations, the second request message may be a handover request message or may be included in a handover request message, which is used to request handover of the first communication device to a third communication device. 703: The third communication device sends a fifth message, and in response, the fourth communication device receives the fifth message, where the fifth message includes a first receiving time point or a first downlink timing. 704: The fourth communication device sends a second message, and in response, the second communication device receives a second message, where the second message indicates the first time information.

[0212] For example, the second message may include one or more of the first time difference, the first downlink timing offset, the first downlink timing, and the first reception time point.

[0213] It can be understood that for a specific description of the first time information, reference should be made to the above related description, and the details will not be described again in this specification. 705: The second communication device determines first time information based on the second message.

[0214] For example, the second communication device may determine the first time information based on one or more of the first time difference, the first downlink timing offset, the first downlink timing, and the first reception time point.

[0215] It can be understood that for a specific description of the first time information, reference should be made to the above related description, and the details will not be described again in this specification. 706: The second communication device sends a first message, and in response, the first communication device receives a first message, where the first message includes first time information.

[0216] In this embodiment of the present application, the first request message may include one or more of a first time difference, a first downlink timing offset, a first downlink timing, and a first receiving time point. The second communication device may determine the first time information based on the second message, so that the first communication device can determine a first TA value based on the first time information to avoid a service interruption caused by obtaining the first TA value in the random access process and reduce the interruption duration in the process of the terminal device switching from the first DU to the second DU.

[0217] 8 is an interaction flowchart of yet another communication method according to an embodiment of the present application. The method shown in FIG. 8 may be applied to the communication system shown in FIG. 2A. Alternatively, the method may be applied to a terminal device, a first DU, a CU, and a second DU. The first DU and the second DU are deployed under the CU. For example, the terminal device may be the first communication device shown above, the first DU may be the second communication device shown above, the CU may be the fourth communication device shown above, and the second DU may be the third communication device shown above. As shown in FIG. 8, the method includes, but is not limited to, the following steps: 801: A first DU sends a first request message, and in response, a CU receives the first request message, where the first request message is used to request a first downlink timing offset.

[0218] In some implementations, the method shown in FIG. 8 includes steps 802 and 803. 802: The CU sends a second request message, and in response, the second DU receives the second request message, where the second request message is used to request a first downlink timing, the first downlink timing is the downlink timing of the second cell, and the second DU is a DU corresponding to the second cell. 803: The CU sends a third request message, and in response, the first DU receives the third request message, where the third request message is used to request a second downlink timing, the second downlink timing is the downlink timing of the first cell, and the first DU is a DU corresponding to the first cell. 804: The second DU sends a fifth message, and in response, the CU receives the fifth message, where the fifth message includes the first downlink timing.

[0219] For example, the first downlink timing may include a first time value, where the first time value is a time corresponding to a first radio frame, a time corresponding to a first subframe, or a time corresponding to a first slot. The first time value may be a global positioning system (GPS) time or a universal time coordinated (UTC) time. For example, the first downlink timing may further include a radio frame number of the first radio frame, a subframe number of the first subframe in the radio frame, or a number of the first slot in the radio frame or subframe.

[0220] Optionally, the fifth message may further include information about the second cell, for example, a cell index of the second cell. 805: The first DU sends a fourth message, and in response, the CU receives the fourth message, where the fourth message includes a second downlink timing.

[0221] For example, the second downlink timing may include a second time value, where the second time value is a time corresponding to a second radio frame, a time corresponding to a second subframe, or a time corresponding to a second slot. The second time value may be GPS time or UTC time. For example, the second downlink timing may further include a radio frame number of the second radio frame, a subframe number of a second subframe in the radio frame, or a second slot number in the radio frame or subframe.

[0222] Optionally, the fourth message may further include information about the first cell, for example, a cell index of the first cell. 806: The CU determines a first downlink timing offset based on the first downlink timing and the second downlink timing.

[0223] For example, the CU may determine a difference between two nearest subframe boundaries of the first cell and the second cell in the time domain based on the first downlink timing and the second downlink timing to obtain a first downlink timing offset. For example, the first time value indicates a time corresponding to the first subframe, and the second time value indicates a time corresponding to the second subframe. If the subframes corresponding to the two nearest subframe boundaries of the first cell and the second cell in the time domain are the first subframe and the second subframe, the CU may calculate a difference between the first time value and the second time value to obtain the first downlink timing offset. 807: The CU sends a second message, and in response, the first DU receives the second message, where the second message includes a first downlink timing offset. 808: The first DU determines first time information based on the first downlink timing offset.

[0224] For example, the first time information indicates a first TA value, and the first time information may include a first TA value, a first time difference, a first downlink timing offset, or a second time difference.

[0225] In a possible implementation, the first time information includes a first downlink timing offset.

[0226] In another possible implementation, the first time information may include a first TA value, and the first DU may determine the first TA value based on the second TA value, the first time difference, and the first downlink timing offset. For example, the first DU may obtain the first TA value through calculation based on Equation (3).

[0227] In yet another possible implementation, the first time information includes a second time difference, and the first DU determines the second time difference based on the first downlink timing offset and the first time difference. For example, the first DU may obtain the second time difference through calculation based on Equation (6). 809: The first DU sends a first message, and in response, the terminal device receives the first message, where the first message includes first time information.

[0228] For example, the first message may be a handover command. In a handover procedure triggered via layer 1 (L1) signaling or layer 2 (L2) signaling, the first DU may send the first downlink timing offset to the terminal device via the handover command. It may be understood that in a handover procedure triggered based on layer 3 (L3) signaling, the CU may directly include the first downlink timing offset in the L3 handover command and send the first downlink timing offset to the terminal device via the L3 handover command. In other words, in a handover procedure triggered based on L3 signaling, steps 801 and 807 do not need to be performed.

[0229] Optionally, when the radio frame numbers and / or subframe numbers corresponding to two nearest subframe boundaries of the first cell and the second cell in the time domain are different, the CU may further determine a first value, where the first value indicates a difference between the radio frame numbers corresponding to the two nearest subframe boundaries and / or a difference between the subframe numbers corresponding to the two nearest subframe boundaries. For example, in a handover procedure triggered via layer L1 signaling or layer L2 signaling, the CU may send the first value to the first DU via the second message, and the first DU may send the first value to the terminal device via the first message. In a handover procedure triggered based on L3 signaling, the CU may include the first value in an L3 handover command and send the first value to the terminal device via the L3 handover command.

[0230] It may be understood that step 801 may be performed before steps 802 to 806 or may be performed after steps 802 to 806. This is not a limitation in the present application. In some possible implementations, the first request message and the fourth message may be the same message, i.e., the message includes the second downlink timing and is used to request the first downlink timing offset.

[0231] In this embodiment of the present application, in a scenario where a first network device and a second network device use the same CU and different DUs (or referred to as an intra-CU inter-DU scenario), a first downlink timing offset may be obtained through an interaction between the first DU and the CU and an interaction between the CU and the second DU, and first time information may be determined based on the first downlink timing offset, so that the terminal device can determine a first TA value based on the first time information to avoid a service interruption caused by obtaining the first TA value in a random access process. In other words, in the present application, the terminal device can perform RACH-less HO to reduce the interruption duration in the process of the terminal device switching from the first DU to the second DU.

[0232] 9 is an interaction flowchart of yet another communication method according to an embodiment of the present application. The method shown in FIG. 9 may be applied to the communication system shown in FIG. 2A. Alternatively, the method may be applied to a terminal device, a first DU, a CU, and a second DU. The first DU and the second DU are deployed under the CU. The terminal device may be the first communication device shown above, the first DU may be the second communication device shown above, the CU may be the fourth communication device shown above, and the second DU may be the third communication device shown above. As shown in FIG. 9, the method includes, but is not limited to, the following steps: 901: A first DU sends a first request message, and in response, a CU receives the first request message, where the first request message is used to request a first downlink timing offset.

[0233] In a possible implementation, the method shown in FIG. 902: The CU sends a second request message, and in response, the second DU receives the second request message, where the second request message is used to request a first downlink timing, the first downlink timing is the downlink timing of the second cell, and the second DU is a DU corresponding to the second cell. 903: The second DU sends a fifth message, and in response, the CU receives the fifth message, where the fifth message includes the first downlink timing. 904: The CU sends a second message, and in response, the first DU receives the second message, where the second message includes the first downlink timing.

[0234] It may be understood that the CU may send the second message after receiving the fifth message, or may send the second message after receiving the first request message. For example, the second DU may periodically report the first downlink timing to the CU. 905: The first DU determines a first downlink timing offset based on the first downlink timing and the second downlink timing.

[0235] It may be understood that for a specific description of the first downlink timing and the second downlink timing, reference should be made to the related descriptions in steps 804 and 805 shown in Fig. 8. Details will not be described again herein. For a specific implementation of determining the first downlink timing offset by the first DU, reference should be made to the related descriptions of determining the first downlink timing offset by the CU in step 806 shown in Fig. 8. Details will not be described again herein. 906: The first DU determines first time information based on the first downlink timing offset.

[0236] It can be understood that the specific implementation of step 906 should refer to the specific implementation of step 808 shown in Figure 8. The details will not be described again in this specification. 907: The first DU sends a first message, and in response, the terminal device receives the first message, where the first message includes first time information.

[0237] In this embodiment of the present application, in a scenario where the first network device and the second network device use the same CU, the first DU may obtain the downlink timing of the second cell through interaction between the CU and the second DU, determine a first downlink timing offset based on the downlink timing of the first cell and the downlink timing of the second cell, and determine first time information based on the first downlink timing offset, so that the terminal device can determine a first TA value based on the first time information to avoid service interruption caused by obtaining the first TA value in the random access process, i.e., reduce the interruption duration in the process of the terminal device switching from the first DU to the second DU.

[0238] 10 is an interaction flowchart of yet another communication method according to an embodiment of the present application. The method shown in FIG. 10 may be applied to the communication system shown in FIG. 2A. Alternatively, the method may be applied to a terminal device, a first DU, a CU, and a second DU. The first DU and the second DU are deployed under the CU. The terminal device may be the first communication device shown above, the first DU may be the second communication device shown above, the CU may be the fourth communication device shown above, and the second DU may be the third communication device shown above. As shown in FIG. 10, the method includes, but is not limited to, the following steps: 1001: A first DU sends a first request message, and in response, a CU receives the first request message, where the first request message is used to request a first time difference, where the first time difference is a difference between a transmission delay from a terminal device to the first DU and a transmission delay from the terminal device to a second DU.

[0239] In a possible implementation, the method shown in FIG. 1002: The CU sends a fourth request message, and in response, the first DU receives the fourth request message, where the fourth request message is used to request reference signal configuration information, and the reference signal configuration information is configuration information of the first reference signal sent by the terminal device.

[0240] For example, the first reference signal may be a sounding reference signal (SRS). Lighting signal structure The configuration information may include a time-frequency resource corresponding to the first reference signal. 1003: The first DU sends a sixth message, and in response, the CU receives the sixth message, where the sixth message includes reference signal configuration information. 1004: The CU sends a seventh message, and in response, the second DU receives the seventh message, where the seventh message includes reference signal configuration information.

[0241] For example, the second DU determines, based on the reference signal configuration information, a time-frequency resource corresponding to the first reference signal sent by the terminal device.

[0242] In a possible implementation, the method shown in FIG. 1005: The CU sends a fifth request message, and in response, the first DU receives the fifth request message, where the fifth request message is used to request a second reception time point. 1006: The CU sends a second request message, and in response, the second DU receives the second request message, where the second request message is used to request the first reception time point. 1007: The terminal device sends out a first reference signal, and in response, the first DU and the second DU receive the first reference signal.

[0243] For example, the first reference signal may be an SRS. The terminal device may send the first reference signal on a time-frequency resource corresponding to the first reference signal. The first DU and the second DU separately receive the first reference signal on the time-frequency resource and record the time points at which the first reference signal is received to obtain the first receiving time point and the second receiving time point. 1008: The first DU sends a third message, and in response, the CU receives the third message, where the third message includes the second receiving time point. 1009: The second DU sends a fifth message, and in response, the CU receives the fifth message, where the fifth message includes the first receiving time point. 1010: The CU determines a first time difference based on the first receiving time point and the second receiving time point.

[0244] For example, the CU calculates the difference between the first reception time point and the second reception time point to obtain the first time difference. 1011: The CU sends a second message, and in response, the first DU receives the second message, where the second message includes a first time difference. 1012: The first DU determines first time information based on the first time difference.

[0245] It can be understood that for a specific description of the first time information, reference should be made to the above related description, and the details will not be described again in this specification. 1013: The first DU sends a first message, and in response, the terminal device receives the first message, where the first message includes first time information.

[0246] In this embodiment of the present application, in the handover procedure triggered based on L3 signaling, the CU may directly include the first time difference in the L3 handover command and send the first time difference to the terminal device through the L3 handover command. In other words, step 1001 and steps 1011 to 1013 do not need to be performed.

[0247] In this embodiment of the present application, in a scenario where the first network device and the second network device use the same CU, the first DU and the second DU exchange reference signal configuration information and reception time point of the first reference signal through the CU, so that the first DU can obtain the first time difference and determine the first time information based on the first time difference, and the terminal device can determine the first TA value based on the first time information to avoid service interruption caused by obtaining the first TA value in the random access process and reduce the interruption duration in the process of the terminal device switching from the first DU to the second DU.

[0248] 11 is an interaction flowchart of yet another communication method according to an embodiment of the present application. The method shown in FIG. 11 may be applied to the communication system shown in FIG. 2B. Alternatively, the method may be applied to a terminal device, a first DU, a CU, and a second DU. The first DU and the second DU are deployed under the CU. The terminal device may be the first communication device shown above, the first DU may be the second communication device shown above, the CU may be the fourth communication device shown above, and the second DU may be the third communication device shown above. As shown in FIG. 11, the method includes, but is not limited to, the following steps: 1101: A first DU sends a first request message, and in response, a CU receives the first request message, where the first request message is used to request a first time difference.

[0249] In a possible implementation, the method shown in FIG. 1102: The CU sends a fourth request message, and in response, the first DU receives the fourth request message, where the fourth request message is used to request reference signal configuration information.

[0250] It can be understood that for a specific description of the reference signal configuration information, reference should be made to the relevant description of step 1002 shown in Figure 10. The details will not be described again in this specification. 1103: The first DU sends a sixth message, and in response, the CU receives the sixth message, where the sixth message includes reference signal configuration information. 1104: The CU sends a seventh message, and in response, the second DU receives the seventh message, where the seventh message includes reference signal configuration information.

[0251] In some possible implementations, the method shown in FIG. 1105: The CU sends a second request message, and in response, the second DU receives the second request message, where the second request message is used to request the first reception time point. 1106: The terminal device sends out a first reference signal, and in response, the first DU and the second DU receive the first reference signal. 1107: The second DU sends a fifth message, and in response, the CU receives the fifth message, where the fifth message includes the first receiving time point. 1108: The CU sends a second message, and in response, the first DU receives the second message, where the second message includes the first receiving time point. 1109: The first DU determines a first time difference based on the first receiving time point and the second receiving time point.

[0252] For example, the first DU calculates the difference between the first receiving time point and the second receiving time point to obtain a first time difference. 1110: The first DU determines first time information based on the first time difference. 1111: A first DU sends a first message, and in response, the terminal device receives the first message, where the first message includes first time information.

[0253] In this embodiment of the present application, in a scenario where the first network device and the second network device use the same CU, the first DU and the second DU exchange reference signal configuration information and reception time point of the first reference signal through the CU, so that the first DU can determine a first time difference and determine first time information based on the first time difference, and the terminal device can determine a first TA value based on the first time information to avoid service interruption caused by obtaining the first TA value in the random access process and reduce the interruption duration in the process of the terminal device switching from the first DU to the second DU.

[0254] 12 is an interaction flowchart of yet another communication method according to an embodiment of the present application. The method shown in FIG. 12 may be applied to the communication system shown in FIG. 2B. Alternatively, the method may be applied to a terminal device, a first network device, and a second network device. The first network device includes a first DU and a first CU, and the second network device includes a second CU and a second DU. The terminal device may be the first communication device shown above, the first DU may be the second communication device shown above, the first CU may be the fourth communication device shown above, and the second CU may be the third communication device shown above. As shown in FIG. 12, the method includes, but is not limited to, the following steps: 1201: A first DU sends a first request message, and in response, a first CU receives the first request message, where the first request message is used to request a first downlink timing offset. 1202: The first CU sends a second request message, and in response, the second CU receives the second request message, where the second request message is used to request a first downlink timing, and the first downlink timing is the downlink timing of the second cell.

[0255] In some implementations, the method shown in FIG. 1203: The second CU sends a sixth request message, and in response, the second DU receives the sixth request message, where the sixth request message is used to request the first downlink timing. 1204: The first CU sends a third request message, and in response, the first DU receives the third request message, where the third request message is used to request a second downlink timing. 1205: The first DU sends a fourth message, and in response, the first CU receives the fourth message, where the fourth message includes a second downlink timing. 1206: The second DU sends an eighth message, and in response, the second CU receives the eighth message, where the eighth message includes the first downlink timing. 1207: The second CU sends a fifth message, and in response, the first CU receives a fifth message, where the fifth message includes the first downlink timing. 1208: The first CU determines a first downlink timing offset based on the first downlink timing and the second downlink timing. 1209: The first CU sends a second message, and correspondingly, the first DU receives the second message, where the second message includes a first downlink timing offset.

[0256] For example, the second message may further include the first value. 1210: The first DU determines first time information based on the first downlink timing offset. 1211: A first DU sends a first message, and in response, the terminal device receives the first message, where the first message includes first time information.

[0257] For example, the first message may further include a first value.

[0258] It may be understood that step 1201 and step 1202 may be performed before step 1203 to step 1206, or may be performed after step 1203 to step 1206. This is not a limitation in the present application.

[0259] It may be understood that in a handover procedure triggered based on L3 signaling, the first CU may directly include the first downlink timing offset in the L3 handover command and may send the first downlink timing offset to the terminal device via the L3 handover command. In other words, step 1201 and steps 1209 to 1211 may not be performed. Optionally, if the first network device and the second network device are in a CU-DU integrated architecture, step 1203, step 1204, step 1205, and step 1206 may not be performed. In other words, in a handover procedure triggered based on L3 signaling, if the first network device and the second network device are in a CU-DU integrated architecture, the method in FIG. 12 may include step 1202, step 1207, and step 1208. The first network device may send the first downlink timing offset to the terminal device via the L3 handover command. For example, the L3 handover command may further include a first value.

[0260] In this embodiment of the present application, in a scenario in which the first network device and the second network device use different CUs (or may be referred to as an inter-CU scenario), a first downlink timing offset may be obtained through interaction between the first DU, the first CU, the second CU, and the second DU, and first time information is determined based on the first downlink timing offset, whereby the first time information can indicate a first TA value, and the terminal device can determine the first TA value based on the first time information to avoid service interruption caused by obtaining the first TA value in the random access process and reduce the interruption duration in the process of the terminal device switching from the first DU to the second DU.

[0261] 13 is an interaction flowchart of yet another communication method according to an embodiment of the present application. The method shown in FIG. 13 may be applied to the communication system shown in FIG. 2B. Alternatively, the method may be applied to a terminal device, a first network device, and a second network device. The first network device includes a first DU and a first CU, and the second network device includes a second CU and a second DU. The terminal device may be the first communication device shown above, the first DU may be the second communication device shown above, the first CU may be the fourth communication device shown above, and the second CU may be the third communication device shown above. As shown in FIG. 13, the method includes, but is not limited to, the following steps: 1301: A first DU sends a first request message, and in response, a first CU receives the first request message, where the first request message is used to request a first downlink timing offset. 1302: The first CU sends a second request message, and in response, the second CU receives the second request message, where the second request message is used to request a first downlink timing.

[0262] In some implementations, the method shown in FIG. 1303: The second CU sends a sixth request message, and in response, the second DU receives the sixth request message, where the sixth request message is used to request the first downlink timing. 1304: The second DU sends an eighth message, and in response, the second CU receives the eighth message, where the eighth message includes the first downlink timing. 1305: The second CU sends a fifth message, and in response, the first CU receives a fifth message, where the fifth message includes the first downlink timing. 1306: The first CU sends a second message, and in response, the first DU receives the second message, where the second message includes the first downlink timing. 1307: The first DU determines a first downlink timing offset based on the first downlink timing and the second downlink timing. 1308: The first DU determines first time information based on the first downlink timing offset. 1309: The first DU sends a first message, and in response, the terminal device receives the first message, where the first message includes first time information.

[0263] It may be understood that step 1301 and step 1302 may be performed before step 1303 and step 1304, or may be performed after step 1303 and step 1304. This is not a limitation in the present application.

[0264] In this embodiment of the present application, in a scenario where the first network device and the second network device use different CUs, the first DU may obtain the downlink timing of the second cell through interaction between the first CU, the second CU, and the second DU, determine a first downlink timing offset based on the downlink timing of the first cell and the downlink timing of the second cell, and determine first time information based on the first downlink timing offset, so that the first time information can indicate a first TA value, and the terminal device can determine the first TA value based on the first time information to avoid service interruption caused by obtaining the first TA value in the random access process and reduce the interruption duration in the process of the terminal device switching from the first DU to the second DU.

[0265] 14 is an interaction flowchart of yet another communication method according to an embodiment of the present application. The method shown in FIG. 14 may be applied to the communication system shown in FIG. 2B. Alternatively, the method may be applied to a terminal device, a first network device, and a second network device. The first network device includes a first DU and a first CU, and the second network device includes a second CU and a second DU. The terminal device may be the first communication device shown above, the first DU may be the second communication device shown above, the first CU may be the fourth communication device shown above, and the second CU may be the third communication device shown above. As shown in FIG. 14, the method includes, but is not limited to, the following steps: 1401: A first DU sends a first request message, and in response, a first CU receives the first request message, where the first request message is used to request a first time difference.

[0266] In a possible implementation, the method shown in FIG. 1402: The first CU sends a fourth request message, and in response, the first DU receives a fourth request message, where the fourth request message is used to request reference signal configuration information, and the reference signal configuration information is configuration information of the first reference signal sent by the terminal device. 1403: The first DU sends a sixth message, and in response, the first CU receives the sixth message, where the sixth message includes reference signal configuration information. 1404: The first CU sends a seventh message, and in response, the second CU receives a seventh message, where the seventh message includes reference signal configuration information. 1405: The second CU sends a ninth message, and in response, the second DU receives a ninth message, where the ninth message includes reference signal configuration information.

[0267] In some possible implementations, the method shown in FIG. 14 may include steps 1406, 1407, and 1408. 1406: The first CU sends a fifth request message, and in response, the first DU receives the fifth request message, where the fifth request message is used to request a second reception time point. 1407: The first CU sends a second request message, and in response, the second CU receives the second request message, where the second request message is used to request the first reception time point. 1408: The second CU sends a sixth request message, and in response, the second DU receives the sixth request message, where the sixth request message is used to request the first reception time point. 1409: The terminal device sends out a first reference signal, and in response, the first DU and the second DU receive the first reference signal. 1410: The first DU sends a third message, and in response, the first CU receives the third message, where the third message includes the second receiving time point. 1411: The second DU sends an eighth message, and in response, the second CU receives the eighth message, where the eighth message includes the first receiving time point. 1412: The second CU sends a fifth message, and in response, the first CU receives a fifth message, where the fifth message includes the first receiving time point. 1413: The first CU determines a first time difference based on the first receiving time point and the second receiving time point. 1414: The first CU sends a second message, and in response, the first DU receives the second message, where the second message includes the first time difference. 1415: The first DU determines first time information based on the first time difference. 1416: The first DU sends a first message, and in response, the terminal device receives the first message, where the first message includes first time information.

[0268] For example, in a handover procedure triggered based on L3 signaling, the first CU may send the first time difference to the terminal device via an L3 handover command. In other words, step 1401 and steps 1414 to 1416 may not be performed in the method shown in Figure 14. Optionally, when the first network device and the second network device are in a CU-DU integrated architecture, step 1402, step 1403, step 1405, step 1406, step 1408, step 1410, and step 1411 may not be performed in the method shown in Figure 14. In other words, when the first network device and the second network device are in a CU-DU integrated architecture, in a handover procedure triggered based on L3 signaling, the first network device and the second network device separately perform the actions performed by the first CU and the second CU in step 1404, step 1412, and step 1413. For example, the first network device may further send the first downlink timing offset to the terminal device via an L3 handover command.

[0269] In this embodiment of the present application, in a scenario where the first network device and the second network device use different CUs, the first DU and the second DU exchange reference signal configuration information and reception time points of the first reference signal through the first CU and the second CU, so that the first DU can obtain the first time difference and determine the first time information based on the first time difference, and the terminal device can determine the first TA value based on the first time information to avoid service interruption caused by obtaining the first TA value in the random access process and reduce the interruption duration in the process of the terminal device switching from the first DU to the second DU.

[0270] 15 is an interaction flowchart of yet another communication method according to an embodiment of the present application. The method shown in FIG. 15 may be applied to the communication system shown in FIG. 2B. Alternatively, the method may be applied to a terminal device, a first network device, and a second network device. The first network device includes a first DU and a first CU, and the second network device includes a second CU and a second DU. The terminal device may be the first communication device shown above, the first DU may be the second communication device shown above, the first CU may be the fourth communication device shown above, and the second CU may be the third communication device shown above. As shown in FIG. 15, the method includes, but is not limited to, the following steps: 1501: A first DU sends a first request message, and in response, a first CU receives the first request message, where the first request message is used to request a first time difference.

[0271] In a possible implementation, the method shown in FIG. 1502: The first CU sends a fourth request message, and in response, the first DU receives the fourth request message, where the fourth request message is used to request reference signal configuration information. 1503: The first DU sends a sixth message, and in response, the first CU receives the sixth message, where the sixth message includes reference signal configuration information. 1504: The first CU sends a seventh message, and in response, the second CU receives a seventh message, where the seventh message includes reference signal configuration information. 1505: The second CU sends a ninth message, and in response, the second DU receives a ninth message, where the ninth message includes reference signal configuration information.

[0272] In some possible implementations, the method shown in FIG. 1506: The first CU sends a second request message, and in response, the second CU receives the second request message, where the second request message is used to request the first reception time point. 1507: The second CU sends a sixth request message, and in response, the second DU receives the sixth request message, where the sixth request message is used to request the first reception time point. 1508: The terminal device sends out a first reference signal, and in response, the first DU and the second DU receive the first reference signal. 1509: The second DU sends an eighth message, and in response, the second CU receives the eighth message, where the eighth message includes the first receiving time point. 1510: The second CU sends a fifth message, and in response, the first CU receives a fifth message, where the fifth message includes the first receiving time point. 1511: The first CU sends a second message, and in response, the first DU receives the second message, where the second message includes the first receiving time point. 1512: The first DU determines a first time difference based on the first receiving time point and the second receiving time point. 1513: The first DU determines first time information based on the first time difference. 1514: The first DU sends a first message, and in response, the terminal device receives the first message, where the first message includes first time information.

[0273] In this embodiment of the present application, in a scenario where the first network device and the second network device use different CUs, the first DU and the second DU exchange reference signal configuration information and reception time points of the first reference signal through the first CU and the second CU, so that the first DU can determine a first time difference and determine first time information based on the first time difference, and the terminal device can determine a first TA value based on the first time information to avoid service interruption caused by obtaining the first TA value in the random access process and reduce the interruption duration in the process of the terminal device switching from the first DU to the second DU.

[0274] A communication device provided in an embodiment of the present application is described below.

[0275] In the present application, the communication device is divided into functional modules based on the embodiment of the aforementioned method. For example, each functional module may be divided into corresponding functions, or two or more functions may be integrated into one processing module. The integrated module may be implemented in the form of hardware or in the form of a software functional module. It should be noted that the module division in the present application is merely an example and represents a logical division of functions. In actual implementation, other division methods may be used. The communication device in the embodiment of the present application will be described in detail below with reference to FIGS. 16 to 18.

[0276] 16 is a structural diagram of a communication device according to an embodiment of the present application. As shown in FIG. 16, the communication device includes: a processing unit 1601, a sending unit 1602, and a receiving unit 1603.

[0277] In some embodiments of the present application, the communication device may be the first communication device (or terminal device) shown above. In other words, the communication device shown in FIG. 16 may be configured to perform the steps, functions, or the like performed by the first communication device (or terminal device) in the above-described method embodiments. For example, the communication device may be a beamforming transmitting device, chip, or the like. This is not limited in this embodiment of the present application.

[0278] The receiving unit 1603 is configured to receive the first message.

[0279] The processing unit 1601 is configured to determine a first TA value.

[0280] The sending unit 1602 is configured to send uplink data.

[0281] Optionally, the processing unit 1601 is further configured to determine a downlink frame timing of the second cell.

[0282] It can be understood that for specific descriptions of the first message, the first TA value, the first time information, and the like, reference should be made to the relevant descriptions of the aforementioned method embodiments, for example, the methods shown in Figures 5, 7, 8, 9, 10, 11, 12, 13, 14, and 15. The details will not be described again in this specification.

[0283] It can be understood that the specific descriptions of the processing unit, the sending unit, and the receiving unit shown in this embodiment of the present application are merely examples. For the specific functions of the processing unit, the sending unit, and the receiving unit, the steps performed by the processing unit, the sending unit, and the receiving unit, or the like, please refer to the above-mentioned method embodiments. The details will not be described again in this specification.

[0284] FIG. 16 is reused. In some other embodiments of the present application, the communication device may be the second communication device (or the first DU) shown above. In other words, the communication device shown in FIG. 16 is the second communication device (or 1st The communication device may be configured to perform steps, functions, or the like performed by a communication unit (DU). For example, the communication device may be a beamforming receiving device, chip, or the like, which is not limited in this embodiment of the present application.

[0285] The processing unit 1601 is configured to determine first time information.

[0286] The sending unit 1602 is configured to send a first message.

[0287] Optionally, the receiving unit 1603 is configured to receive a second message.

[0288] Optionally, the sending unit 1602 is further configured to send a fourth message.

[0289] Optionally, the receiving unit 1603 is further configured to receive a first reference signal.

[0290] Optionally, the sending unit 1602 is further configured to send a third message.

[0291] Optionally, the sending unit 1602 is further configured to send the first request message.

[0292] It may be understood that for specific descriptions of the first time information, the first message, the second message, the third message, the fourth message, the first request message, and the like, reference should be made to the relevant descriptions of the aforementioned method embodiments, for example, the methods shown in Figures 5, 7, 8, 9, 10, 11, 12, 13, 14, and 15. The details will not be described again in this specification.

[0293] It can be understood that the specific descriptions of the receiving unit, the sending unit, and the processing unit shown in this embodiment of the present application are merely examples. For the specific functions of the receiving unit, the sending unit, and the processing unit, the steps performed by the receiving unit, the sending unit, and the processing unit, or the like, please refer to the above-mentioned method embodiments. The details will not be described again in this specification.

[0294] Figure 16 In some other embodiments of the present application, the communication device may be the fourth communication device (or CU or first CU) shown above. Figure 16 The illustrated communication device may be configured to perform the steps, functions, or the like performed by the fourth communication device (or CU or first CU) in the above-described method embodiment. For example, the communication device may be a beamforming receiving device, chip, or the like. This is not limited in this embodiment of the present application.

[0295] The receiving unit 1603 is configured to receive the fifth message.

[0296] The sending unit 1602 is further configured to send a second message.

[0297] Optionally, the receiving unit 1603 is further configured to receive a third message; and the processing unit 1601 is configured to determine the first time difference.

[0298] Optionally, the receiving unit 1603 is further configured to receive a fourth message; and the processing unit 1601 is configured to determine a first downlink timing offset.

[0299] Optionally, the receiving unit 1603 is further configured to receive a first request message.

[0300] Optionally, the sending unit 1602 is further configured to send a second request message.

[0301] It can be understood that for specific descriptions of the second message, the third message, the fourth message, the fifth message, the first time difference, and the first downlink timing offset, reference should be made to the relevant descriptions of the aforementioned method embodiments, for example, the methods shown in Figures 5, 7, 8, 9, 10, 11, 12, 13, 14, and 15. The details will not be described again in this specification.

[0302] It can be understood that the specific descriptions of the receiving unit, the sending unit, and the processing unit shown in this embodiment of the present application are merely examples. For the specific functions of the receiving unit, the sending unit, and the processing unit, the steps performed by the receiving unit, the sending unit, and the processing unit, or the like, please refer to the above-mentioned method embodiments. The details will not be described again in this specification.

[0303] Figure 1616 may be reused. In some other embodiments of the present application, the communication device may be the third communication device (or the second DU or the second CU) shown above. In other words, the communication device shown in FIG. 16 may be configured to perform the steps, functions, or the like performed by the third communication device (or the second DU or the second CU) in the above-mentioned method embodiments. For example, the communication device may be a beamforming receiving device, chip, or the like. This is not limited in this embodiment of the present application.

[0304] The receiving unit 1603 is configured to receive the second request message.

[0305] The sending unit 1602 is configured to send the fifth message.

[0306] Optionally, the receiving unit 1603 is further configured to receive a first reference signal.

[0307] It can be understood that for specific descriptions of the second request message, the fifth message, and the first reference signal, reference should be made to the relevant descriptions of the aforementioned method embodiments, for example, the methods shown in Figures 5, 7, 8, 9, 10, 11, 12, 13, 14, and 15. The details will not be described again in this specification.

[0308] It can be understood that the specific descriptions of the receiving unit, the sending unit, and the processing unit shown in this embodiment of the present application are merely examples. For the specific functions of the receiving unit, the sending unit, and the processing unit, the steps performed by the receiving unit, the sending unit, and the processing unit, or the like, please refer to the above-mentioned method embodiments. The details will not be described again in this specification.

[0309] The above describes the first communication device, the second communication device, the third communication device, and the fourth communication device in the embodiments of the present application. The following describes possible product forms of the first communication device, the second communication device, the third communication device, and the fourth communication device. It should be understood that any form of product having the function of the first communication device in FIG. 16, any form of product having the function of the second communication device in FIG. 16, any form of product having the function of the third communication device in FIG. 16, or any form of product having the function of the fourth communication device in FIG. 16 falls within the scope of protection of the embodiments of the present application. It should be further understood that the following description is merely an example and does not limit the product forms of the first communication device, the second communication device, the third communication device, and the fourth communication device in the embodiments of the present application.

[0310] 16, the processing unit 1601 may be one or more processors, the sending unit 1602 may be a transmitter, the receiving unit 1603 may be a receiver, or the sending unit and the receiving unit may be integrated into one component, for example, a transceiver. Alternatively, the processing unit 1601 may be one or more processors (or the processing unit 1601 may be one or more logic circuits), the sending unit 1602 may be an output interface, the receiving unit 1603 may be an input interface, or the input interface and the output interface may be integrated into one unit, for example, an input / output interface. Details will be described below.

[0311] In a possible implementation, in the communication device shown in Fig. 16, the processing unit 1601 may be one or more processors, and the sending unit 1602 and the receiving unit 1603 are integrated into one component, for example, a transceiver. In this embodiment of the present application, the processor and the transceiver may be combined, or the like. The connection manner between the processor and the transceiver is not limited in this embodiment of the present application.

[0312] As shown in FIG. 17, the communications device 170 includes one or more processors 1720 and a transceiver 1710 .

[0313] For example, when the communication device is configured to perform the steps, methods, or functions performed by a first communication device, the transceiver 1710 is configured to receive a first message and send uplink data; and the processor 1720 is configured to determine a first TA value. Optionally, the processor 1720 is further configured to determine a downlink frame timing of the second cell.

[0314] For example, when the communications device is configured to perform a step, method, or function performed by a second communications device, the processor 1720 is configured to determine first time information; and the transceiver 1710 is configured to send a first message. Optionally, the transceiver 1710 is further configured to receive a second message. Optionally, the transceiver 1710 is further configured to send a fourth message. Optionally, the transceiver 1710 is further configured to receive a first reference signal. Optionally, the transceiver 1710 is further configured to send a third message. Optionally, the transceiver 1710 is further configured to send a first request message.

[0315] For example, when the communications device is configured to perform the steps, methods, or functions performed by a fourth communications device, the transceiver 1710 is configured to receive the fifth message and send the second message. Optionally, the transceiver 1710 is further configured to receive the third message; and the processor 1720 is configured to determine the first time difference. Optionally, the transceiver 1710 is further configured to receive the fourth message, and the processor 1720 is configured to determine a first downlink timing offset, and the like.

[0316] For example, if the communication device is configured to perform the steps, methods, or functions performed by a third communication device, the transceiver 1710 is configured to receive the second request message and send the fifth message. Optionally, the transceiver 1710 is further configured to receive a first reference signal.

[0317] It may be understood that for specific descriptions of the first time information, the first message, the second message, the third message, the fourth message, the fifth message, the first request message, the second request message, the first reference signal, and the like, reference should be made to the relevant descriptions of the aforementioned method embodiments, for example, the methods shown in Figures 5, 7, 8, 9, 10, 11, 12, 13, 14, and 15. The details will not be described again in this specification.

[0318] It can be understood that for a specific description of the processor and the transceiver, reference should be made to the description of the processing unit, the sending unit, and the receiving unit shown in Figure 16. The details will not be described again in this specification.

[0319] Figure 17 In various implementations of the illustrated communications apparatus, the transceiver may include a receiver and a transmitter, where the receiver is configured to perform receiving functions (or operations) and the transmitter is configured to perform transmitting functions (or operations), and the transceiver is configured to communicate with another device / apparatus over a transmission medium.

[0320] Optionally, the communication device 170 may further include one or more memories 1730 configured to store program instructions and / or data. The memory 1730 is coupled to the processor 1720. The coupling in this embodiment of the present application may be an indirect coupling or communication connection between devices, units, or modules in an electrical, mechanical, or other form, used for information exchange between the devices, units, or modules. The processor 1720 may cooperate with the memory 1730. The processor 1720 may execute program instructions stored in the memory 1730. Optionally, at least one of the one or more memories may be included in the processor.

[0321] The specific connection medium between the transceiver 1710, the processor 1720, and the memory 1730 is not limited in this embodiment of the present application. In this embodiment of the present application, the memory 1730, the processor 1720, and the transceiver 1710 are connected through a bus 1740 in FIG. 17. The bus is indicated by using bold lines in FIG. 17. The manner of connection between other components is only an example for illustration and may not be construed as limiting. The bus may be classified as an address bus, a data bus, a control bus, and the like. For ease of representation, only one bold line is used to represent a bus in FIG. 17, but this does not mean that there is only one bus or only one type of bus.

[0322] In this embodiment of the present application, the processor may be a general-purpose processor, a digital signal processor, an application-specific integrated circuit, a field programmable gate array or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, or the like. The processor can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of the present application. The general-purpose processor may be a microprocessor or any conventional processor or the like. The steps of the methods disclosed in connection with the embodiments of the present application may be implemented directly by a hardware processor, or may be implemented by using a combination of hardware and software modules in a processor or the like.

[0323] In this embodiment of the present application, the memory may include, but is not limited to, a non-volatile memory, such as a hard disk drive (HDD) or solid-state drive (SSD), a random access memory (RAM), an erasable programmable read-only memory (EPROM), a read-only memory (ROM), or a compact disc read-only memory (CD-ROM). The memory is any storage medium that can be used to carry or store program code in the form of instructions or data structures and that can be read and / or written by a computer (e.g., a communication device shown in this application). However, the present application is not limited thereto. The memory in this embodiment of the present application may alternatively be a circuit or any other device capable of implementing a memory function and configured to store program instructions and / or data.

[0324] The processor 1720 is primarily configured to process communication protocols and communication data, control the entire communication device, execute software programs, and process data of the software programs. The memory 1730 is primarily configured to store software programs and data. The transceiver 1710 may include control circuitry and an antenna. The control circuitry is primarily configured to convert between baseband signals and radio frequency signals and process the radio frequency signals. The antenna is primarily configured to receive or transmit radio frequency signals in the form of electromagnetic waves. An input / output device, such as a touchscreen, display, or keyboard, is primarily configured to receive data input by a user and output data to a user.

[0325] After the communication device is powered on, the processor 1720 may read the software program in the memory 1730, interpret and execute the instructions of the software program, and process the data of the software program. When data needs to be transmitted wirelessly, the processor 1720 performs baseband processing on the data to be transmitted and outputs the baseband signal to the radio frequency circuit. The radio frequency circuit performs radio frequency processing on the baseband signal and then transmits the radio frequency signal to the outside through an antenna in the form of electromagnetic waves. When data is transmitted to the communication device, the radio frequency circuit receives the radio frequency signal through the antenna, converts the radio frequency signal into a baseband signal, and outputs the baseband signal to the processor 1720. The processor 1720 converts the baseband signal into data and processes the data.

[0326] In another implementation, the radio frequency circuitry and antenna may be located independently from the processor that performs the baseband processing, e.g., in a distributed scenario, the radio frequency circuitry and antenna may be located independently and remotely from the communication device.

[0327] It can be understood that the communication device shown in this embodiment of the present application may alternatively include more components than those shown in FIG. 17 or similar. This is not limited to this embodiment of the present application. The methods performed by the processor and transceiver are merely examples. Please refer to the methods described above for specific steps performed by the processor and transceiver.

[0328] In another possible implementation, in the communication device shown in FIG. 16 , the processing unit 1601 may be one or more logic circuits, the sending unit 1602 may be an output interface, and the receiving unit 1603 may be an input interface, and the input interface and the output interface may be integrated into one unit, such as an input / output interface. The input / output interface may also be referred to as a communication interface, an interface circuit, an interface, or the like. As shown in FIG. 18 , the communication device shown in FIG. 18 includes a logic circuit 1801 and an interface 1802. In other words, the processing unit 1601 may be implemented using the logic circuit 1801, and the sending unit 1602 and the receiving unit 1603 may be implemented using the interface 1802. The logic circuit 1801 may be a chip, a processing circuit, an integrated circuit, a system on chip (SoC), or the like. The interface 1802 may be a communication interface, an input / output interface, a pin, or the like. For example, in FIG. 18, the aforementioned communication device is illustrated by using a chip as an example, where the chip includes a logic circuit 1801 and an interface 1802 .

[0329] In this embodiment of the present application, the logic circuit and the interface may be coupled to each other, and the specific manner of connection between the logic circuit and the interface is not limited in this embodiment of the present application.

[0330] For example, when the communication device is configured to perform a method, function, or step performed by a first communication device, the interface 1802 is configured to input a first message and output uplink data; and the logic circuit 1801 is configured to determine a first TA value. Optionally, the processor 1720 is further configured to determine a downlink frame timing of the second cell.

[0331] For example, when the communication device is configured to perform a method, function, or step performed by a second communication device, logic circuit 1801 is configured to determine first time information; and interface 1802 is configured to output a first message. Optionally, interface 1802 is further configured to input a second message. Optionally, interface 1802 is further configured to output a fourth message. Optionally, interface 1802 is further configured to input a first reference signal. Optionally, interface 1802 is further configured to output a third message. Optionally, interface 1802 is further configured to output a first request message.

[0332] For example, when the communications device is configured to perform the steps, methods, or functions performed by a fourth communications device, interface 1802 is configured to input a fifth message and output a second message. Optionally, interface 1802 is further configured to input a third message; and logic circuit 1801 is configured to determine a first time difference. Optionally, interface 1802 is further configured to input a fourth message and logic circuit 1801 is configured to determine a first downlink timing offset.

[0333] It can be understood that the communication device shown in the embodiments of the present application may implement the method provided in the embodiments of the present application in the form of hardware, or may implement the method provided in the embodiments of the present application in the form of software, which is not limited to the embodiments of the present application.

[0334] It may be understood that for specific descriptions of the first time information, the first message, the second message, the third message, the fourth message, the fifth message, the first request message, the second request message, the first reference signal, and the like, reference should be made to the relevant descriptions of the aforementioned method embodiments, for example, the methods shown in Figures 5, 7, 8, 9, 10, 11, 12, 13, 14, and 15. The details will not be described again in this specification.

[0335] For specific implementation of the embodiment shown in Figure 18, please refer to the above-mentioned embodiment, and the details will not be described in this specification.

[0336] An embodiment of the present application further provides a communication system, including at least one of the following: a first communication device, a second communication device, a third communication device, and a fourth communication device, wherein the first communication device, the second communication device, the third communication device, and the fourth communication device may be configured to perform the method in any one of the previous embodiments (as shown in Figures 5, 7, 8, 9, 10, 11, 12, 13, 14, and 15).

[0337] Additionally, the present application further provides a computer program, which is used to implement the actions and / or processes performed by the first communication device in the methods provided herein.

[0338] The present application further provides a computer program, which can be used to implement the actions and / or processes performed by the second communication device in the methods provided herein.

[0339] The present application further provides a computer program, the computer program being configured to implement the actions and / or processes performed by the third communication device in the methods provided herein.

[0340] The present application further provides a computer program, the computer program being configured to implement the actions and / or processes performed by the fourth communication device in the methods provided herein.

[0341] The present application further provides a computer-readable storage medium having computer code stored thereon that, when executed on a computer, enables the computer to perform the actions and / or processes performed by the first communication device in the methods provided herein.

[0342] The present application further provides a computer-readable storage medium having stored thereon computer code that, when executed on a computer, enables the computer to perform the actions and / or processes performed by the second communication device in the methods provided herein.

[0343] The present application further provides a computer-readable storage medium having computer code stored therein that, when executed on a computer, enables the computer to perform the actions and / or processes performed by a third communication device in the methods provided herein.

[0344] The present application further provides a computer-readable storage medium having computer code stored thereon that, when executed on a computer, enables the computer to perform the actions and / or processes performed by the fourth communication device in the methods provided herein.

[0345] The present application further provides a computer program product, the computer program product including computer code or a computer program that, when executed on a computer, performs the operations and / or processes performed by the first communications device in the methods provided herein.

[0346] The present application further provides a computer program product, the computer program product including computer code or a computer program that, when executed on a computer, performs the actions and / or processes performed by the second communication device in the methods provided herein.

[0347] The present application further provides a computer program product, the computer program product including computer code or a computer program that, when executed on a computer, performs the actions and / or processes performed by the third communications device in the methods provided herein.

[0348] The present application further provides a computer program product, the computer program product including computer code or a computer program that, when executed on a computer, performs the actions and / or processes performed by the fourth communication device in the methods provided herein.

[0349] An embodiment of the present application further provides a chip or chip system including a processor configured to perform the method in any one of the above-mentioned embodiments (as shown in Figures 5, 7, 8, 9, 10, 11, 12, 13, 14, and 15).

[0350] In some embodiments provided herein, it should be understood that the disclosed systems, devices, and methods may be implemented in other manners. For example, the described device embodiment is merely an example. For example, the division into multiple units is merely a logical division of functionality, and actual implementation may involve other divisions. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not implemented. In addition, the shown or discussed mutual couplings or direct couplings or communication connections may be implemented through some interfaces, indirect couplings or communication connections between devices or units, or electrical, mechanical, or other types of connections.

[0351] The units described as separate parts may or may not be physically separate, and the parts shown as units may or may not be physical units, located in one location or distributed over multiple network units. Some or all of the units may be selected based on actual requirements to implement the technical effects of the solutions provided in the embodiments of the present application.

[0352] In addition, the functional units in the embodiments of the present application may be integrated into one processing unit, or each of the units may exist physically alone, or two or more units may be integrated into one unit. The integrated unit may be implemented in the form of hardware or in the form of a software functional unit.

[0353] When an integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, the integrated unit may be stored in a computer-readable storage medium. Based on this understanding, the technical solutions of the present application may essentially be implemented in the form of a software product, or a portion contributing to the prior art, or all or some of the technical solutions may be implemented in the form of a software product. The computer software product is stored in a readable storage medium and includes a plurality of instructions for instructing a computer device (which may be a personal computer, a server, or a network device) to perform all or some of the steps of the methods described in the embodiments of the present application. The readable storage medium includes any medium that can store program code, such as a USB flash drive, a removable hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0354] The above description is merely a specific implementation of the present application and is not intended to limit the scope of protection of the present application. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application shall fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be subject to the scope of protection of the claims.

Claims

1. 1. A communication method, the method being applied to a first communication device, receiving a first message from a second communication device, wherein the first message includes first time information, the first time information being determined based on a first transmission delay and a second transmission delay, the first transmission delay being a transmission delay from the first communication device to the second communication device, the second transmission delay being a transmission delay from the first communication device to a third communication device, the second communication device being a communication device corresponding to a first cell, and the third communication device being a communication device corresponding to a second cell; determining a first timing advance (TA) value of the second cell based on the first time information; and sending uplink data to the third communication device based on the first TA value; A method comprising:

2. 2. The method of claim 1, wherein the first time information indicates the first TA value, the first TA value being determined based on a second TA value and a first time difference, the second TA value being the TA value of the first cell or the TA value of a first timing advance group (TAG) of the first communication device, and the first time difference being the difference between the first transmission delay and the second transmission delay.

3. determining a first timing advance (TA) value of the first cell based on the first time information, determining the first TA value based on the first time information and a second TA value, wherein the second TA value is a TA value of the first cell or a TA value of a first TAG of the first communication device; 2. The method of claim 1, comprising:

4. The method of claim 3 , wherein the first message further includes first indication information, the first indication information indicating the first TAG.

5. the first time information includes a first time difference, the first time difference being a difference between the first transmission delay and the second transmission delay, and the step of determining the first TA value based on the first time information and a second TA value includes: determining the first TA value based on the first time difference and the second TA value; 5. The method of claim 3 or 4, comprising:

6. The first time information further includes a first downlink timing offset, the first downlink timing offset being a downlink timing offset between the first cell and the second cell, and the step of determining the first TA value based on the first time difference and the second TA value includes: determining the first TA value based on the first time difference, the second TA value, and the first downlink timing offset; The method of claim 5 , comprising:

7. 7. The method of claim 6, wherein the first TA value satisfies TA1=TA2-2*(UL_TDOA-Δ), where TA1 is the first TA value, TA2 is the second TA value, UL_TDOA is the first time difference, and Δ is the first downlink timing offset.

8. The method comprises: determining a downlink frame timing of the second cell based on the first time difference and the first downlink frame timing, where the first downlink frame timing is the downlink frame timing of the first cell or the downlink frame timing of the first TAG; The method according to any one of claims 5 to 7, further comprising:

9. The method of claim 8 , wherein the downlink frame timing of the second cell is obtained by adjusting the first downlink frame timing forward or backward by the first time difference.

10. the first time information includes a second time difference, the second time difference being a difference between a round-trip transmission delay from the first communication device to the second communication device and a round-trip transmission delay from the first communication device to the third communication device, and the step of determining the first TA value based on the first time information and a second TA value comprises: determining the first TA value based on the second time difference and the second TA value; 5. The method of claim 3 or 4, comprising:

11. 11. The method of claim 10, wherein the second time difference is determined based on a first time difference and a first downlink timing offset, wherein the first time difference is a difference between the first transmission delay and the second transmission delay, and the first downlink timing offset is a downlink timing offset between the first cell and the second cell.

12. 12. The method according to claim 10 or 11, wherein the first TA value satisfies TA1=TA2-TA_offset, where TA1 is the first TA value, TA2 is the second TA value, and TA_offset is the second time difference.

13. 1. A communication method, the method being applied to a second communication device; determining first time information, where the first time information is determined based on a first transmission delay and a second transmission delay, the first transmission delay being a transmission delay from a first communication device to the second communication device, the second transmission delay being a transmission delay from the first communication device to a third communication device, the second communication device being a communication device corresponding to a first cell, and the third communication device being a communication device corresponding to a second cell; and sending a first message to the first communication device, wherein the first message includes the first time information; A method comprising:

14. 14. The method of claim 13, wherein the first time information indicates a first TA value, the first TA value being determined based on a second TA value and a first time difference, the first TA value being the TA value of the second cell, the second TA value being the TA value of the first cell or the TA value of a first timing advance group (TAG) of the first communication device, and the first time difference being a difference between the first transmission delay and the second transmission delay.

15. The method of claim 13 , wherein the first time information comprises a first time difference, the first time difference being a difference between the first transmission delay and the second transmission delay.

16. 16. The method of claim 15, wherein the first time information further includes a first downlink timing offset, the first downlink timing offset being a downlink timing offset between the first cell and the second cell.

17. 14. The method of claim 13, wherein the first time information includes a second time difference, the second time difference being a difference between a round-trip transmission delay from the first communication device to the second communication device and a round-trip transmission delay from the first communication device to the third communication device, the second time difference being determined based on a first time difference, and the first time difference being a difference between the first transmission delay and the second transmission delay.

18. 18. The method of claim 17, wherein the second time difference is determined based on the first time difference and a first downlink timing offset, the first downlink timing offset being a downlink timing offset between the first cell and the second cell.

19. The method comprises: receiving a second message from a fourth communication device, wherein the second message indicates the first time information; further comprising: The step of determining first time information comprises: determining the first time information based on the second message; The method according to any one of claims 13 to 18, comprising:

20. the second message includes the first downlink timing offset, and the step of determining the first time information based on the second message includes: determining the first time information based on the first downlink timing offset; 20. The method of claim 19, comprising:

21. The method comprises: sending a fourth message to the fourth communication device, wherein the fourth message includes a second downlink timing, the second downlink timing being the downlink timing of the first cell; 21. The method of claim 20, further comprising:

22. the second message includes a first downlink timing, the first downlink timing being a downlink timing of the second cell, and the method further comprises: determining the first downlink timing offset based on the first downlink timing and a second downlink timing, where the second downlink timing is the downlink timing of the first cell; further comprising: determining the first time information based on the second message; determining the first time information based on the first downlink timing offset; 20. The method of claim 19, comprising:

23. 23. The method of claim 22, wherein the first downlink timing comprises a time corresponding to a radio frame, a time corresponding to a subframe, or a time corresponding to a slot.

24. the second message includes the first time difference, and the step of determining the first time information based on the second message includes: determining the first time information based on the first time difference; 20. The method of claim 19, comprising:

25. The method comprises: receiving a first reference signal from the first communication device; and sending a third message to the fourth communication device, wherein the third message includes the second reception time, the second reception time being the time at which the second communication device receives the first reference signal; 25. The method of claim 24, further comprising:

26. The second message includes a first reception time point, and the first reception time point is a time point at which a first reference signal of the first communication device is transmitted to the third communication device, and the method further comprises: determining the first time difference based on the first reception time point and a second reception time point, wherein the second reception time point is a time point at which the second communication device receives the first reference signal; further comprising: determining the first time information based on the second message; determining the first time information based on the first time difference; 20. The method of claim 19, comprising:

27. The method comprises: sending a first request message to the fourth communication device, wherein the first request message is used to request retrieval of the second message; The method of any one of claims 19 to 26, further comprising:

28. A communication method, the method being applied to a fourth communication device; receiving a fifth message from a third communication device, wherein the fifth message includes a first reception time or a first downlink timing, the first reception time being a time when a first reference signal of the first communication device is transmitted to the third communication device, the first downlink timing being a downlink timing of a second cell, and the third communication device being a communication device corresponding to the second cell; and sending a second message to a second communication device based on the first reception time point or the first downlink timing, wherein the second message indicates first time information, the first time information being determined based on a first transmission delay and a second transmission delay, the first transmission delay being a transmission delay from the first communication device to the second communication device, and the second transmission delay being a transmission delay from the first communication device to the third communication device, and the second communication device being a communication device corresponding to a first cell; A method comprising:

29. the fifth message includes the first reception time point, the second message includes a first time difference, the first time difference being a difference between the first transmission delay and the second transmission delay, and the method further comprising: receiving a third message from the second communication device, wherein the third message includes a second reception time point, the second reception time point being a time point at which the first reference signal is transmitted to the second communication device; and determining the first time difference based on the first reception time and the second reception time; 30. The method of claim 28, further comprising:

30. the fifth message includes the first downlink timing, the second message includes a first downlink timing offset, the first downlink timing offset being a downlink timing offset between the first cell and the second cell, and the method further comprises: receiving a fourth message from the second communication device, wherein the fourth message includes a second downlink timing, the second downlink timing being the downlink timing of the first cell; and determining the first downlink timing offset based on the first downlink timing and the second downlink timing; 30. The method of claim 28, further comprising:

31. 29. The method of claim 28, wherein the second message includes the first reception time or the first downlink timing.

32. The method comprises: receiving a first request message from the second communication device, wherein the first request message is used to request retrieval of the second message; The method of any one of claims 28 to 31, further comprising:

33. The method comprises: sending a second request message to the third communication device, wherein the second request message is used to request acquiring the first reception time point or the first downlink timing; The method of any one of claims 28 to 32, further comprising:

34. A communication method, the method being applied to a third communication device; receiving a second request message from a fourth communication device, where the second request message is used to request a first reception time point or a first downlink timing, the first reception time point being a time point at which a first reference signal of the first communication device is transmitted to the third communication device, the first downlink timing being a downlink timing of a second cell, and the third communication device being a communication device corresponding to the second cell; and sending a fifth message to the fourth communication device, wherein the fifth message includes the first reception time or the first downlink timing; A method comprising:

35. The method comprises: receiving the first reference signal 35. The method of claim 34, further comprising:

36. A communications device comprising a unit configured to perform the method of any one of claims 1 to 12, or comprising a unit configured to perform the method of any one of claims 13 to 27, or comprising a unit configured to perform the method of any one of claims 28 to 33, or comprising a unit configured to perform the method of any one of claims 34 and 35.

37. A communication device, a processor and a memory, the memory configured to store computer-executable instructions; 20. A communications device, wherein the processor is configured to execute the computer-executable instructions, thereby performing the method of any one of claims 1 to 12; performing the method of any one of claims 13 to 27; performing the method of any one of claims 28 to 33; or performing the method of any one of claims 34 and 35.

38. 1. A computer-readable storage medium configured to store a computer program, the computer-readable storage medium being configured to, when executed, perform the method of any one of claims 1 to 12; the method of any one of claims 13 to 27; the method of any one of claims 28 to 33; or the method of any one of claims 34 and 35.

39. 1. A communication system comprising at least two of the following: a first communication device, a second communication device, a third communication device and a fourth communication device, wherein the first communication device is configured to perform the method of any one of claims 1 to 12, the second communication device is configured to perform the method of any one of claims 13 to 27, the third communication device is configured to perform the method of any one of claims 34 and 35 and the fourth communication device is configured to perform the method of any one of claims 28 to 33.

40. 1. A computer program product comprising a computer program which, when run on a computer, performs the method of any one of claims 1 to 12; the method of any one of claims 13 to 27; the method of any one of claims 28 to 33; or the method of any one of claims 34 and 35.

Images