Communication method and device

Abstract

A communication method and apparatus, particularly suitable for a non-terrestrial network, the method comprising: a terminal device determines that a first duration needs to be acquired, determines the first duration, and determines a timing advance according to the first duration, the timing advance being used for communication between the terminal device and a network device. According to the method, the terminal equipment can determine the first duration according to own needs, so that the energy consumption of the terminal equipment can be reduced; besides, the terminal equipment can also calculate the timing advance changing along with time according to the auxiliary parameters from the network equipment, so that the energy consumption for frequently reading the system messages is reduced.

Description

[0001] This application is a divisional application. The application number of the original application is 202080086688.3, and the original application date is January 14, 2020. The entire content of the original application is incorporated herein by reference. Technical Field

[0002] This application relates to the field of wireless communication technologies, and particularly relates to a communication method and apparatus. Background Art

[0003] In the fifth generation (5G) communication system, non-terrestrial Networks (NTN) are introduced. Non-terrestrial Networks refer to a communication network in which devices such as aircraft or satellites are introduced into the communication system as relay nodes or base stations.

[0004] In non-terrestrial networks, since devices such as aircraft or satellites participate in the communication process, the propagation distance between the terminal device and the base station is relatively long. Taking the example of the terminal device sending data to the base station, the data needs to be transmitted to the satellite relay node and then transmitted by the satellite relay node to the base station, or the data needs to be transmitted to the satellite serving as the base station. Compared with the traditional public land mobile network, the propagation distance is relatively long, resulting in the round-trip time of data transmission can reach tens of milliseconds to hundreds of milliseconds.

[0005] Since the timing advance of the terminal device is related to the round-trip time of data transmission, therefore, for non-terrestrial networks, how the terminal device obtains the timing advance still needs further research. Summary of the Invention

[0006] This application provides a communication method and apparatus to solve the problem of how the terminal device obtains the timing advance in the NTN scenario.

[0007] In a first aspect, an embodiment of this application provides a communication method. This method can be applied to a terminal device or a chip inside the terminal device. Taking the case where this method is applied to the terminal device as an example, in this method, if the terminal device determines that it needs to obtain a first duration, it can determine the first duration and determine the timing advance (TA) amount according to the first duration. The timing advance amount is used for communication between the terminal device and the network device.

[0008] By using the above method, the terminal device can determine the first duration according to its own needs, thereby reducing the energy consumption of the terminal device.

[0009] In a possible design, if the terminal device determines to trigger a random access process, it determines that it needs to obtain a first duration.

[0010] In a possible design, determining that the first duration needs to be obtained includes: determining that the terminal device has no valid first duration, or determining that the terminal device has no available first duration.

[0011] In a possible design, the triggering reasons for the random access procedure do not include system message requests and beam failure recovery.

[0012] In a possible design, determining the first duration includes: receiving a system message from a network device, where the system message is used to carry the first duration.

[0013] Using the above method, when the terminal device determines that the first duration needs to be obtained, it reads the system message, that is, the terminal device's reading of the system message is not restricted by the existing system message change mechanism, so that it can not only ensure that the terminal device obtains the first duration, but also effectively avoid the terminal device from frequently reading the system message and reduce the power consumption of the terminal device.

[0014] In a possible design, determining the first duration includes: determining the first duration according to the first auxiliary parameter; where the first auxiliary parameter includes the position information of the ground reference point, or the first auxiliary parameter includes the position information of the ground reference point and the position information of the network device; or determining the first duration according to the second auxiliary parameter, where the second auxiliary parameter includes the initial value of the first duration, the time information corresponding to the initial value, and the change rate of the first duration.

[0015] In a possible design, the method further includes: receiving the first auxiliary parameter and / or the second auxiliary parameter from the network device.

[0016] In a possible design, the first duration is determined according to the first auxiliary parameter and the satellite ephemeris, where the satellite ephemeris comes from the network device or the core network device, or the satellite ephemeris is pre-configured; where the network device is located on the satellite, or the satellite is a relay node for communication between the terminal device and the network device.

[0017] In a possible design, determining the timing advance according to the first duration includes: obtaining a second duration, and then determining the timing advance according to the first duration and the second duration.

[0018] In a possible design, obtaining the second duration includes: receiving a random access response from the network device, where the random access response includes the second duration.

[0019] In a possible design, obtaining the second duration includes: receiving a random access response from the network device, where the random access response includes a fourth duration; receiving an adjustment value of the fourth duration from the network device, and determining the second duration according to the fourth duration and the adjustment value.

[0020] By adopting the above method, on the one hand, the accuracy of the second duration can be effectively guaranteed. On the other hand, since the network device can send an adjustment value to the terminal device without having to resend the second duration, the transmission resources can be effectively saved.

[0021] In a second aspect, an embodiment of the present application provides a communication method. This method can be applied to a terminal device or a chip inside the terminal device. Taking the case where this method is applied to a terminal device as an example, in this method, the terminal device receives a first auxiliary parameter from a network device; the first auxiliary parameter includes the position of a ground reference point, or the first auxiliary parameter includes the position of a ground reference point and the position of the network device; and, the terminal device determines a first duration according to the first auxiliary parameter, and the first duration is used to determine a timing advance, and the timing advance is used for communication between the terminal device and the network device.

[0022] By adopting this solution, the terminal device can determine the first duration according to the first auxiliary parameter, thereby effectively avoiding the terminal device from frequently reading system messages and reducing the power consumption of the terminal device.

[0023] In a possible design, the first duration is determined according to the first auxiliary parameter and satellite ephemeris; the method further includes: obtaining satellite ephemeris; where the network device is located on a satellite, or the satellite is a relay node for communication between the terminal device and the network device.

[0024] In a possible design, obtaining satellite ephemeris includes: receiving satellite ephemeris from a network device or a core network device.

[0025] In a possible design, the first auxiliary parameter is carried in a system message from the network device.

[0026] In a possible design, before determining the first duration according to the first auxiliary parameter, it further includes: determining that a duration needs to be obtained.

[0027] In a possible design, determining that a first duration needs to be obtained includes: determining that a random access procedure is triggered.

[0028] In a possible design, determining that a first duration needs to be obtained includes: determining that the terminal device does not have a valid first duration.

[0029] In a third aspect, an embodiment of the present application provides a communication method. This method can be applied to a terminal device or a chip inside the terminal device. Taking the case where this method is applied to a terminal device as an example, in this method, the terminal device receives second auxiliary parameters from a network device; the second auxiliary parameters include an initial value of a first duration, time information corresponding to the initial value, and a change rate of the first duration; and the terminal device determines the first duration according to the second auxiliary parameters, and the first duration is used to determine a timing advance, and the timing advance is used for communication between the terminal device and the network device.

[0030] Adopting this solution, the terminal device can determine the first duration according to the second auxiliary parameters, thereby effectively avoiding the terminal device from frequently reading system messages and reducing the power consumption of the terminal device.

[0031] In a possible design, receiving the second auxiliary parameters from the network device includes: receiving a system message from the network device, and the system message includes the second auxiliary parameters.

[0032] In a possible design, before determining the first duration according to the second auxiliary parameters, it further includes: determining that a duration needs to be obtained.

[0033] In a possible design, determining that the first duration needs to be obtained includes: determining that a random access process is triggered.

[0034] In a possible design, determining that the first duration needs to be obtained includes: determining that the terminal device has no valid first duration.

[0035] In a fourth aspect, an embodiment of the present application provides a communication method. This method can be applied to a terminal device or a chip inside the terminal device. Taking the case where this method is applied to a terminal device as an example, in this method, the terminal device determines a first change period of a first system message, and the first system message is used to carry a first duration, and the first duration is used to determine a first timing advance, and the first timing advance is used for communication between the terminal device and a first network device; and the terminal device receives the first system message from the first network device according to the first change period; wherein, the first change period is different from a second change period of a second system message, and the second system message comes from the first network device.

[0036] Adopting the above method, by designing a new change period for the first system message, further, the terminal device can read the first system message according to the change period of the first system message without reading other system messages other than the first system message, thereby effectively avoiding the terminal device from reading unnecessary system messages and reducing the power consumption of the terminal device.

[0037] In a possible design, the first change period is less than the second change period.

[0038] Since the first change period is relatively small, it can effectively ensure that the terminal device can obtain the first system message in a timely manner.

[0039] In a possible design, according to the first change period, receive the first system message from the first network device, including: within each first change period, receive the first system message from the first network device.

[0040] In a possible design, according to the first change period, receive the first system message from the first network device, including: receive the first indication information from the first network device, where the first indication information is used to indicate that the first system message has changed; and, within the first change period where the first indication information is located, receive the updated first system message.

[0041] By using the above method, the terminal device can read the first system message when the first system message changes according to the first indication information, thereby avoiding the terminal device from frequently reading the first system message and further reducing the power consumption of the terminal device.

[0042] In a possible design, the first system message is further used to carry a third duration, and the third duration is used to determine a second timing advance, and the second timing advance is used for communication between the terminal device and the second network device.

[0043] In a possible design, according to the first change period, receive the first system message from the first network device, including: receive the second indication information from the first network device, where the second indication information is used to indicate that the first duration has changed or is used to indicate that the third duration has changed; within the first change period where the second indication information is located, receive the first system message.

[0044] By using the above method, the second indication information can clearly indicate whether it is the second duration and / or the third duration that has changed, so that the terminal device can know the changed duration, read the changed duration, and can no longer read the unchanged duration, effectively reducing the power consumption of the terminal device.

[0045] In a possible design, the first network device is the serving network device of the terminal device, and the second network device is the candidate serving network device of the terminal device.

[0046] In a fifth aspect, an embodiment of the present application provides a communication method, which can be applied to a terminal device or a chip inside the terminal device. Taking the case where the method is applied to the terminal device as an example, in this method, the terminal device receives a first duration from a source network device and determines a timing advance according to the first duration, and the timing advance is used for communication between the terminal device and a target network device.

[0047] By adopting the above method, the terminal device obtains the first duration corresponding to the target network device through the source network device, so that there is no need to read the system message of the target network device to obtain the first duration, effectively reducing the power consumption of the terminal device.

[0048] In a possible design, the first duration is carried in the RRC reconfiguration message from the source network device.

[0049] In a possible design, determining the timing advance according to the first duration includes: obtaining a second duration, and then determining the timing advance according to the first duration and the second duration.

[0050] In a possible design, obtaining the second duration includes: receiving a random access response from the target network device, where the random access response includes the second duration; or, receiving a random access response from the target network device, where the random access response includes a fourth duration; receiving an adjustment value of the fourth duration from the target network device, and determining the second duration according to the fourth duration and the adjustment value.

[0051] In a sixth aspect, an embodiment of the present application provides a communication method, which can be applied to a terminal device or a chip inside the terminal device. Taking the method applied to the terminal device as an example, in this method, the terminal device receives downlink control information from a network device, the downlink control information is used to instruct the terminal device to trigger a random access process, and the downlink control information includes a first duration; and, the terminal device determines a timing advance according to the first duration, and the timing advance is used for communication between the terminal device and the network device.

[0052] By adopting the above method, the terminal device can obtain the first duration through the PDCCH order, so that there is no need to read the system message of the network device to obtain the first duration, effectively reducing the power consumption of the terminal device.

[0053] In a possible design, determining the timing advance according to the first duration includes: obtaining a second duration, and then determining the timing advance according to the first duration and the second duration.

[0054] In a possible design, obtaining the second duration includes: receiving a random access response from the target network device, where the random access response includes the second duration; or, receiving a random access response from the target network device, where the random access response includes a fourth duration; receiving an adjustment value of the fourth duration from the target network device, and determining the second duration according to the fourth duration and the adjustment value.

[0055] Seventh aspect, an embodiment of the present application provides a communication method, which can be applied to a network device or a chip inside the network device. Taking the application of this method to a network device as an example, in this method, the network device determines auxiliary parameters, where the auxiliary parameters include the position of a ground reference point, or the auxiliary parameters include the position of the ground reference point and the position of the network device, or the auxiliary parameters include the initial value of a first duration, the time information corresponding to the initial value, and the change rate of the first duration; and sends the auxiliary parameters to the terminal device.

[0056] In a possible design, sending the auxiliary parameters to the terminal device includes: sending a system message to the terminal device, and the auxiliary parameters are carried in the system message.

[0057] In a possible design, this method further includes: sending satellite ephemeris to the terminal device; where the network device is located on the satellite, or the satellite is a relay node for communication between the terminal device and the network device.

[0058] Eighth aspect, an embodiment of the present application provides a communication method, which can be applied to a network device or a chip inside the network device. Taking the application of this method to a first network device as an example, in this method, the first network device determines a first change period of a first system message, where the first system message is used to carry a first duration, the first duration is used to determine a first timing advance, and the first timing advance is used for communication between the terminal device and the first network device; and sends third indication information to the terminal device, where the third indication information is used to indicate the first change period; where the first change period is different from the second change period of a second system message, and the second system message comes from the first network device.

[0059] In a possible design, this method further includes: sending first indication information to the terminal device, where the first indication information is used to indicate that the first system message has changed.

[0060] In a possible design, the first system message is further used to carry a third duration, the third duration is used to determine a second timing advance, and the second timing advance is used for communication between the terminal device and a second network device.

[0061] In a possible design, this method further includes: sending second indication information to the terminal device, where the second indication information is used to indicate that the first duration has changed or is used to indicate that the third duration has changed.

[0062] In a ninth aspect, an embodiment of the present application provides a communication method, which can be applied to a network device or a chip inside the network device. Taking the case where the method is applied to a source network device as an example, in this method, the source network device receives a first duration from a target network device, the first duration determines a timing advance, and the timing advance is used for communication between a terminal device and the target network device; and, the source network device sends the first duration to the terminal device.

[0063] In a possible design, receiving the first duration from the target network device includes: sending a handover request to the target network device and receiving a handover response from the target network device, where the handover response includes the first duration.

[0064] In a possible design, sending the first duration to the terminal device includes: sending an RRC reconfiguration message to the terminal device, where the RRC reconfiguration message includes the first duration.

[0065] In a tenth aspect, an embodiment of the present application provides a communication method, which can be applied to a network device or a chip inside the network device. Taking the case where the method is applied to a target network device as an example, in this method, the target network device determines a first duration, the first duration determines a timing advance, and the timing advance is used for communication between a terminal device and the target network device; and, the target network device sends the first duration to the source network device.

[0066] In a possible design, sending the first duration to the source network device includes: receiving a handover request from the source network device and sending a handover response to the source network device, where the handover response includes the first duration.

[0067] In an eleventh aspect, an embodiment of the present application provides a communication method, which can be applied to a network device or a chip inside the network device. Taking the case where the method is applied to a network device as an example, in this method, the network device determines a first duration, the first duration determines a timing advance, and the timing advance is used for communication between a terminal device and the target network device; and, the network device sends downlink control information to the terminal device, where the downlink control information is used to instruct the terminal device to trigger a random access process, and the downlink control information includes the first duration.

[0068] It should be noted that since the communication methods described in the above seventh aspect to eleventh aspect correspond to the communication methods described in the first aspect to sixth aspect, the related beneficial effects of the communication methods described in the seventh aspect to eleventh aspect can be referred to the first aspect to sixth aspect. Further, in the above first aspect to eleventh aspect, the beneficial effects of the same or corresponding features can be referred to each other.

[0069] In a twelfth aspect, the present application provides a communication device, which may be a terminal device or a chip disposed inside the terminal device. The communication device has the functions of implementing the above first aspect to the sixth aspect. For example, the communication device includes modules or units or means corresponding to the steps involved in the above first aspect to the sixth aspect. The functions or units or means may be implemented by software, or by hardware, or by hardware executing corresponding software.

[0070] In a possible design, the communication device includes a processing unit and a communication unit. Among them, the communication unit may be used to transmit and receive signals to implement communication between the communication device and other devices. For example, the communication unit is used to receive system messages from a network device; the processing unit may be used to perform some internal operations of the communication device. The functions performed by the processing unit and the communication unit may correspond to the steps involved in the above first aspect to the sixth aspect.

[0071] In a possible design, the communication device includes a processor and may further include a transceiver. The transceiver is used to transmit and receive signals. The processor executes program instructions to complete the methods in any possible design or implementation manner in the above first aspect to the sixth aspect. Among them, the communication device may further include one or more memories, and the memories are used to be coupled with the processor. The one or more memories may be integrated with the processor or may be separately provided from the processor, which is not limited in the present application. The memories may store necessary computer programs or instructions for implementing the functions involved in the above first aspect to the sixth aspect. The processor may execute the computer programs or instructions stored in the memories. When the computer programs or instructions are executed, the communication device implements the methods in any possible design or implementation manner in the above first aspect to the sixth aspect.

[0072] In a possible design, the communication device includes a processor and a memory. The memory may store necessary computer programs or instructions for implementing the functions involved in the above first aspect to the sixth aspect. The processor may execute the computer programs or instructions stored in the memory. When the computer programs or instructions are executed, the communication device implements the methods in any possible design or implementation manner in the above first aspect to the sixth aspect.

[0073] In a possible design, the communication device includes at least one processor and an interface circuit. Among them, the at least one processor is used to communicate with other devices through the interface circuit and execute the methods in any possible design or implementation manner in the above first aspect to the sixth aspect.

[0074] In a thirteenth aspect, the present application provides a communication device, which may be a network device or a chip disposed inside a network device. The communication device is capable of implementing the functions related to the seventh to eleventh aspects described above. For example, the communication device includes modules, units, or means corresponding to the steps involved in the seventh to eleventh aspects described above. The functions, units, or means may be implemented by software, or by hardware, or by hardware executing corresponding software.

[0075] In a possible design, the communication device includes a processing unit and a communication unit. The communication unit may be used to transmit and receive signals to implement communication between the communication device and other devices. For example, the communication unit is used to send system messages to a terminal device. The processing unit may be used to perform some internal operations of the communication device. The functions performed by the processing unit and the communication unit may correspond to the steps involved in the seventh to eleventh aspects described above.

[0076] In a possible design, the communication device includes a processor and may further include a transceiver. The transceiver is used to transmit and receive signals. The processor executes program instructions to complete the methods in any possible design or implementation manner in the seventh to eleventh aspects described above. The communication device may further include one or more memories, which are used to be coupled to the processor. The one or more memories may be integrated with the processor or may be separately provided from the processor, which is not limited in the present application. The memory may store necessary computer programs or instructions for implementing the functions related to the seventh to eleventh aspects described above. The processor may execute the computer programs or instructions stored in the memory. When the computer programs or instructions are executed, the communication device implements the methods in any possible design or implementation manner in the seventh to eleventh aspects described above.

[0077] In a possible design, the communication device includes a processor and a memory. The memory may store necessary computer programs or instructions for implementing the functions related to the seventh to eleventh aspects described above. The processor may execute the computer programs or instructions stored in the memory. When the computer programs or instructions are executed, the communication device implements the methods in any possible design or implementation manner in the seventh to eleventh aspects described above.

[0078] In a possible design, the communication device includes at least one processor and an interface circuit. The at least one processor is used to communicate with other devices through the interface circuit and execute the methods in any possible design or implementation manner in the seventh to eleventh aspects described above.

[0079] In a fourteenth aspect, the present application provides a computer-readable storage medium storing computer-readable instructions, which, when read and executed by a computer, cause the computer to execute the method in any of the possible designs of the first to eleventh aspects described above.

[0080] In a fifteenth aspect, the present application provides a computer program product, which, when read and executed by a computer, causes the computer to execute the method in any of the possible designs of the first to eleventh aspects described above.

[0081] In a sixteenth aspect, the present application provides a chip including a processor coupled to a memory for reading and executing a software program stored in the memory to implement the method in any of the possible designs of the first to eleventh aspects described above.

[0082] These aspects or other aspects of the present application will be more clearly understood in the following description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Figure 1a FIG. is a schematic diagram of a network architecture applicable to an embodiment of the present application;

[0084] Figure 1b FIG. is another schematic diagram of a network architecture applicable to an embodiment of the present application;

[0085] Figure 1c FIG. is another schematic diagram of a network architecture applicable to an embodiment of the present application;

[0086] Figure 2 FIG. is a schematic diagram of uplink synchronization provided by an embodiment of the present application;

[0087] Figure 3a FIG. is a calculation example diagram of common TA and UE specific TA provided by an embodiment of the present application;

[0088] Figure 3b FIG. is another calculation example diagram of common TA and UE specific TA provided by an embodiment of the present application;

[0089] Figure 4a FIG. is a schematic flowchart corresponding to the communication method provided by Embodiment 1 of the present application;

[0090] Figure 4b FIG. is a schematic diagram of system messages periodically sent by a network device provided by an embodiment of the present application;

[0091] Figure 5 FIG. is a schematic flowchart corresponding to the communication method provided by Embodiment 2 of the present application;

[0092] Figure 6a It is a schematic flowchart corresponding to the communication method provided in the third embodiment of this application;

[0093] Figure 6b It is an example of the change period of the first system message and the change period of the second system message provided in the embodiment of this application;

[0094] Figure 6c It is an example of receiving the first system message within the same change period provided in the embodiment of this application;

[0095] Figure 7 It is a schematic flowchart corresponding to the communication method provided in the fourth embodiment of this application;

[0096] Figure 8 It is a schematic flowchart corresponding to the communication method provided in the fifth embodiment of this application;

[0097] Figure 9 It is a possible exemplary block diagram of the device involved in the embodiment of this application;

[0098] Figure 10 It is a schematic structural diagram of a terminal device provided in the embodiment of this application;

[0099] Figure 11 It is a schematic structural diagram of a network device provided in the embodiment of this application. Detailed implementation manners

[0100] Next, the technical solutions in the embodiments of the present invention will be described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0101] First, some terms in the embodiments of this application are explained to facilitate the understanding of those skilled in the art.

[0102] (1) Terminal device: It can be a wireless terminal device capable of receiving scheduling and indication information from a network device. The wireless terminal device can be a device that provides voice and / or data connectivity to users, or a handheld device with wireless connection capabilities, or other processing devices connected to a wireless modem. The terminal device can communicate with one or more core networks or the Internet via a radio access network (RAN). The terminal device can be a mobile terminal device, such as a mobile phone (or called a "cellular" phone, mobile phone), computer, and data card. For example, it can be a portable, pocket-sized, handheld, computer-integrated, or vehicle-mounted mobile device that exchanges voice and / or data with the wireless access network. For example, personal communication service (PCS) phones, cordless phones, session initiation protocol (SIP) phones, wireless local loop (WLL) stations, personal digital assistants (PDAs), tablets (Pad), computers with wireless transceiver functions, etc. The wireless terminal device can also be called a system, subscriber unit, subscriber station, mobile station, mobile station (MS), remote station, access point (AP), remote terminal, access terminal, user terminal, user agent, subscriber station (SS), customer premises equipment (CPE), terminal, user equipment (UE), mobile terminal (MT), etc. The terminal device can also be a wearable device and the next-generation communication system. For example, the terminal device in a 5G communication system or the terminal device in a future evolved public land mobile network (PLMN), etc.

[0103] (2) Network device: It can be a device in a wireless network. For example, the network device can be a radio access network (RAN) node (or device) that connects a terminal device to the wireless network, and can also be referred to as a base station. Currently, some examples of RAN devices are: the new generation Node B (gNodeB) in a 5G communication system, transmission reception point (TRP), evolved Node B (eNB), radio network controller (RNC), Node B (NB), base station controller (BSC), base transceiver station (BTS), home base station (such as home evolved Node B, or home Node B, HNB), base band unit (BBU), or wireless fidelity (Wi-Fi) access point (AP), etc. Additionally, in a network structure, the network device can include a centralized unit (CU) node, or a distributed unit (DU) node, or a RAN device including a CU node and a DU node. Furthermore, in other possible cases, the network device can be other devices that provide wireless communication functions for terminal devices. The embodiments of the present application do not limit the specific technologies and specific device forms adopted by the network device. For ease of description, in the embodiments of the present application, the device that provides wireless communication functions for the terminal device is referred to as a network device.

[0104] (3) The terms "system" and "network" in the embodiments of the present application can be used interchangeably. "At least one" means one or more, and "a plurality" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, or B exists alone, where A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after. "At least one (item)" or its similar expression refers to any combination of these items, including any combination of single items (items) or multiple items (items). For example, "at least one of A, B, and C" includes A, B, C, AB, AC, BC, or ABC.

[0105] Moreover, unless otherwise specified, the ordinal numbers such as "first" and "second" mentioned in the embodiments of this application are used to distinguish multiple objects, and are not used to limit the order, time sequence, priority, or importance of multiple objects. For example, the first network device and the second network device are only used to distinguish different network devices, rather than indicating differences in the priority or importance of these two network devices, etc.

[0106] See Figure 1a , which is a schematic diagram of a network architecture applicable to the embodiments of this application. As Figure 1a shown, the terminal device 130 can be connected to a wireless network to obtain services from the external network (such as the Internet) through the wireless network, or communicate with other devices through the wireless network, such as communicating with other terminal devices. The wireless network includes a radio access network (RAN) device 110 and a core network (CN) device 120. The RAN device 110 is used to connect the terminal device 130 to the wireless network, and the CN device 120 is used to manage the terminal device and provide a gateway for communicating with the external network. It should be understood that Figure 1a the number of each device in the communication system shown is only for illustration, and the embodiments of this application are not limited thereto. In actual applications, the communication system may also include more terminal devices 130, more RAN devices 110, and may also include other devices.

[0107] Exemplarily, Figure 1a the network architecture shown can be applicable to a PLMN or can also be applicable to an NTN. The NTN can include a satellite communication system, a high altitude platform (HAPS) communication system, or other non-terrestrial communication systems.

[0108] Next, taking Figure 1a the network architecture shown is applicable to a satellite communication system as an example, two possible scenarios are described, which are respectively called Scenario 1 and Scenario 2.

[0109] See Figure 1b , which is a schematic diagram of the network architecture of Scenario 1 of the embodiments of this application. As Figure 1b shown, taking the RAN device 110 being deployed on a satellite (such as a low earth orbit satellite) as an example, this scenario can also be called a regenerative payload.

[0110] See Figure 1c , which is a schematic diagram of the network architecture of Scenario 2 of the embodiments of this application. As Figure 1cAs shown, the RAN device 110 is deployed on the ground. When the terminal device 130 communicates with the RAN device 110, the signal is relayed by a satellite. In this scenario, the satellite acts as a relay node or repeater, and this scenario can also be referred to as a transparent payload.

[0111] It should be noted that: (1) The satellite involved in the embodiments of this application may refer to a satellite capable of automatically adjusting its beam (NTN with steerable beams). Exemplarily, since the satellite is constantly moving around the Earth, the projection of the satellite signal on the ground is constantly changing. Therefore, the satellite can adjust its beam automatically so that the projection on the ground remains unchanged as the satellite moves.

[0112] (2) The satellite involved in the embodiments of this application may be a geostationary earth orbiting (GEO) satellite, or it may also be a low earth orbiting (LEO) satellite, and a low earth orbiting satellite can also be referred to as a near-earth orbit satellite.

[0113] (3) The Figure 1a 、 Figure 1b or Figure 1c The network architectures shown can be applied to communication systems of various radio access technologies (RATs). For example, it can be an LTE communication system, or a 5G (or new radio (NR)) communication system, or a transitional system between an LTE communication system and a 5G communication system, and this transitional system can also be referred to as a 4.5G communication system. Of course, it can also be a future communication system. The network architectures and service scenarios described in the embodiments of this application are to more clearly illustrate the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided by the embodiments of this application. Those of ordinary skill in the art know that with the evolution of communication network architectures and the emergence of new service scenarios, the technical solutions provided by the embodiments of this application are equally applicable to similar technical problems.

[0114] In Figure 1a 、 Figure 1b or Figure 1cIn the network architecture shown, the terminal device can communicate with the network device. The communication between the terminal device and the network device can include uplink transmission and downlink transmission. Taking the uplink transmission as an example, an important feature of the uplink transmission is that different terminal devices perform orthogonal multiple access in time-frequency, that is, the uplink transmissions of different terminal devices from the same cell do not interfere with each other. To ensure the orthogonality of the uplink transmission and avoid in-cell interference, the network device requires that the signals of different terminal devices from the same subframe but different frequency-domain resources arrive at the network device at basically aligned times. If the network device receives the uplink data sent by the terminal device within the cyclic prefix (CP) range, it can correctly decode the uplink data. Therefore, the uplink synchronization requires that the signals of different terminal devices from the same subframe arrive at the network within the CP.

[0115] To achieve uplink synchronization, the network device can indicate the timing advance (TA) amount to the terminal device. Correspondingly, the terminal device can adjust the uplink transmission time according to the timing advance amount, so that the uplink data sent by each terminal device arrives at the network device at an aligned time; among them, the timing advance amount is related to the round-trip time of data transmission. For example, the timing advance amount can be equal to twice the round-trip time of data transmission. From the perspective of the terminal device, the timing advance amount can be understood as a negative offset between the time of receiving the downlink signal and the time of transmitting the uplink signal; by controlling the offset of each terminal device, the network device can control the time when the uplink signals from different terminal devices arrive at the network device. For example, since the transmission delay of the terminal device farther from the network device is larger than that of the terminal device closer to the network device, the network device can control the terminal device farther from the network device to transmit the uplink signal earlier than the terminal device closer to the network device. Among them, the timing advance amount can also be abbreviated as timing advance, and the timing advance can also be called time advance.

[0116] For example, Figure 2 As an example diagram of uplink synchronization, as Figure 2 shown, the terminal device 2 is farther from the network device, and the terminal device 1 is closer to the network device. To enable the network device to receive the uplink data at time T0, the terminal device 1 needs to perform uplink transmission at time T2 according to TA1, and the terminal device 2 needs to perform uplink transmission at time T1 according to TA2 (TA2 is greater than TA1).

[0117] Next, the method for the network device in the PLMN to indicate the timing advance amount to the terminal device will be introduced.

[0118] In a PLMN, there can be multiple ways for a network device to indicate the timing advance to a terminal device. For example, the network device can send a timing advance command to the terminal device, and the timing advance command is used to indicate the timing advance amount.

[0119] In a possible implementation, the network device can send a timing advance command to the terminal device during the random access procedure. For example, the network device can estimate the timing advance amount of the terminal device based on the random access preamble sent by the terminal device, and then send the timing advance command to the terminal device through a random access response (RAR); correspondingly, the terminal device can obtain the timing advance amount according to the timing advance command. Among them, in an LTE communication system, the timing advance command can include 11 bits; in a 5G communication system, the timing advance command can include 12 bits. The timing advance command can indicate the index of the timing advance amount, and then the terminal device can calculate the timing advance amount according to the index of the timing advance amount.

[0120] In another possible implementation, the network device can send a timing advance command to a terminal device in the connected state. Exemplarily, after the terminal device achieves uplink synchronization with the network device during the random access procedure, the timing advance amount may become invalid due to various reasons. Therefore, the terminal device needs to continuously update the timing advance amount. Among them, the reasons for the invalidation of the timing advance amount can include: for example, (1) for a terminal device moving at high speed (such as a terminal device on a running high-speed train), the transmission delay between it and the network device will constantly change; (2) the current transmission path disappears and switches to a new transmission path. For example, in a city with dense buildings, when the terminal device moves to the corner of a building, the current transmission path may disappear and a new transmission path needs to be switched; (3) the crystal oscillator offset of the terminal device, and the long-term accumulated offset may cause the timing advance amount to become invalid; (4) the Doppler frequency shift caused by the movement of the terminal device may cause the timing advance amount to become invalid.

[0121] In this implementation, the network device can determine the timing advance amount of each terminal device based on measuring the uplink transmission of the terminal device. Therefore, when the terminal device performs uplink transmission, the network device can estimate the timing advance amount according to the uplink transmission. In theory, any signal sent by the terminal device can be used to estimate the timing advance amount. When the network device determines that a specific terminal device needs to be corrected, it can send a timing advance command to the terminal device, requiring the terminal device to adjust the timing advance amount. Among them, the network device can send the timing advance command to the terminal device through a media access control (MAC) control element (CE).

[0122] However, in NTN, due to the long distance between the terminal device and the satellite, the round-trip time of data transmission between the terminal device and the network device is relatively large. For example, for a geostationary satellite, the maximum round-trip time may reach 541.46 ms, and for a low-earth orbit satellite, the maximum round-trip time may reach 25.77 ms. Therefore, for the NTN scenario, the timing advance required by the terminal device is much larger than that in the PLMN scenario. Since the number of bits included in the timing advance command in RAR and MAC CE is limited, the value of the timing advance it indicates is also limited. Thus, it is impossible to directly adopt the method described above in PLMN to indicate the timing advance of the terminal device.

[0123] Based on this, the embodiments of the present application provide a communication method for enabling a terminal device to obtain a timing advance in the NTN scenario.

[0124] Exemplarily, in the embodiments of the present application, the timing advance can be divided into two parts, one part is the common timing advance (common TA), and the other part is the timing advance specific to the terminal device (UE specific TA).

[0125] Among them, in Figure 1b the scenario shown, referring to Figure 3a shown, common TA and UE specific TA respectively conform to the following formulas:

[0126] common TA = 2 * d0 / c

[0127] UE specific TA = 2 * (d1 - d0) / c

[0128] Wherein, d0 represents the distance between the satellite and the ground reference point, and the ground reference point can be preset; d1 represents the distance between the satellite and the terminal device; c represents the speed of light.

[0129] In Figure 1c the scenario shown, referring to Figure 3b shown, common TA and UE specific TA respectively conform to the following formulas:

[0130] common TA = 2 * (d0 + d0_F) / c

[0131] UE specific TA = 2 * (d1 - d0) / c

[0132] Wherein, d0_F represents the distance between the satellite and the network device.

[0133] As can be seen from the above, common TA is related to d0, and d0 changes continuously as the satellite moves. Therefore, common TA also changes continuously as the satellite moves. It can be understood that in the NTN scenario, there are other parameters related to d0 that also change continuously as the satellite moves. Therefore, it is necessary to frequently notify the terminal device to update.

[0134] As introduced above, all terminal devices within the coverage of the network device need to obtain common TA. Therefore, a possible way is that the network device can send common TA through system messages. Correspondingly, the terminal device can obtain common TA by reading system messages. Among them, the system message can include multiple system information blocks (SIBs), such as SIB a, SIB b, and SIB c. Common TA can be carried in at least one SIB. For example, common TA is carried in SIB a. However, since common TA is constantly changing (i.e., SIB a is constantly changing), it causes the system message to change frequently. Correspondingly, the terminal device needs to frequently read the system message, resulting in an increase in the energy consumption of the terminal device. Further, the multiple system information blocks included in the system message correspond to the same change period. When a certain system information block included in the system message changes, the terminal device needs to read the system message according to the change period. For example, when SIB a changes while SIB b and SIB c do not change, the terminal device needs to read the system message according to the change period, that is, read SIB a, SIB b, and SIB c, resulting in the terminal device frequently reading unnecessary system messages (such as SIB b and SIB c), with relatively high energy consumption.

[0135] Based on the above problems, in the embodiments of the present application, it will be studied how to obtain common TA and UE specific TA (i.e., obtain the timing advance) to reduce the energy consumption of the terminal device.

[0136] The technical solutions provided in the embodiments of the present application will be introduced in detail below with reference to Embodiments 1 to 5.

[0137] In the following introduction process, it is assumed that the method is applied to Figure 1bTaking the network architecture shown in Figure 1c as an example. Additionally, this method can be executed by two communication devices, such as a first communication device and a second communication device. Among them, the first communication device can be a network device or a communication device capable of supporting the functions required for the network device to implement this method. Of course, it can also be other communication devices, such as a chip or a chip system. The second communication device can be a terminal device or a communication device capable of supporting the functions required for the terminal device to implement this method. Of course, it can also be other communication devices, such as a chip or a chip system. For the convenience of introduction, hereinafter, an example is given where this method is executed by a network device and a terminal device, that is, an example where the first communication device is a network device and the second communication device is a terminal device. If this embodiment is applied to Figure 1b or Figure 1c the network architecture shown, the network device described hereinafter for executing Figure 4a , Figure 5 , Figure 6a , Figure 7 or Figure 8 the embodiments shown can be Figure 1b or Figure 1c the network device in the system architecture shown. The terminal device described hereinafter for executing Figure 4a , Figure 5 , Figure 6a , Figure 7 or Figure 8 the embodiments shown can be Figure 1b or Figure 1c the terminal device in the system architecture shown.

[0138] Exemplarily, the communication method provided in the embodiments of the present application may include five possible solutions, which are referred to as Solution 1 to Solution 5 for the convenience of description.

[0139] In Solution 1, the network device can broadcast a first duration through a system message. If the terminal device determines that it needs to obtain the first duration, it can receive the system message from the network device and obtain the first duration, and then determine the timing advance according to the first duration. By adopting this solution, when the terminal device determines that it needs to obtain the first duration, it reads the system message, that is, the terminal device's reading of the system message is not restricted by the existing system message change mechanism, so that it can not only ensure that the terminal device obtains the first duration, but also effectively avoid the terminal device from frequently reading the system message and reduce the power consumption of the terminal device.

[0140] In Solution 2, the network device sends auxiliary parameters to the terminal device. The terminal device can determine the first duration based on the auxiliary parameters, and then determine the timing advance according to the first duration. By adopting this solution, the terminal device can determine the first duration based on the auxiliary parameters, thus effectively avoiding the terminal device from frequently reading system messages and reducing the power consumption of the terminal device. Further, since the auxiliary parameters generally do not change frequently (for example, the auxiliary parameters may include the location information of the ground reference point, or the auxiliary parameters include the location information of the ground reference point and the location information of the network device, and the location information of the ground reference point and the location information of the network device are usually static and unchanged), therefore, the network device does not need to send the auxiliary parameters to the terminal device frequently and multiple times, thus effectively saving transmission resources; moreover, the terminal device determines the first duration based on the auxiliary parameters, without the network device determining the first duration, thus effectively saving the processing burden of the network device.

[0141] In Solution 3, the network device can send the first duration through the first system message. The change period of the first system message is different from that of the second system message from the network device, that is to say, the network device can design a new change period for the first system message. In this way, the terminal device can read the first system message according to the change period of the first system message, without reading other system messages other than the first system message, thus effectively avoiding the terminal device from reading unnecessary system messages and reducing the power consumption of the terminal device. In addition, the network device can also send indication information to the terminal device. The indication information is used to indicate that the first system message has changed. The terminal device can read the first system message according to the indication information, thus avoiding the terminal device from frequently reading the first system message and further reducing the power consumption of the terminal device.

[0142] In Solution 4, the source network device can obtain the first duration from the target network device, and then send the first duration to the terminal device through the RRC reconfiguration message, so that the terminal device does not need to read the system message of the target network device to obtain the first duration, effectively reducing the power consumption of the terminal device.

[0143] In Solution 5, the network device can send the first duration to the terminal device through the PDCCH order, so that the terminal device does not need to read the system message of the network device to obtain the first duration, effectively reducing the power consumption of the terminal device. Moreover, on the one hand, since the first duration that the terminal device needs to use is clearly indicated through the PDCCH order, the problem that the terminal device does not know which first duration to use when the network device has multiple first durations is avoided; on the other hand, when the first duration changes, the network device can quickly indicate the changed first duration to the terminal device through the PDCCH order, so that the terminal device can obtain the changed first duration in time.

[0144] It should be noted that in the embodiments of the present application, the first duration may be a common TA, and the second duration may be a UE-specific TA.

[0145] Embodiment 1

[0146] In Embodiment 1, a possible implementation of the communication method will be described based on the above Solution 1.

[0147] Figure 4a is the flowchart corresponding to the communication method provided in Embodiment 1 of the present application. As Figure 4a shown, it includes:

[0148] Step 401, the network device sends a system message, and the system message is used to indicate the first duration.

[0149] Exemplarily, there are various ways for the system message to indicate the first duration. For example, the system message includes the first duration or the system message includes information for indicating the first duration (such as the index of the first duration), and specific details are not limited.

[0150] Exemplarily, the system message may include a first system information block, and the first system information block may be used to indicate the first duration. Among them, the first system information block may be a newly defined system information block, such as SIB X. The following is an example of a configuration format of SIB X:

[0151]

[0152] In the embodiments of the present application, the network device may send the system message periodically. For example, the network device may send the system message according to the repetition period of the system message. Refer to Figure 4b shown, which is a schematic diagram of the system message periodically sent by the network device. It should be noted that within a system message change period, the content of the system message sent by the network device according to the repetition period may be the same.

[0153] Optionally, the change period and / or repetition period used by the network device to send SIB X may be different from the change period and / or repetition period used by other system messages except SIB X, where the repetition period may also be referred to as the transmission period.

[0154] Step 402, the terminal device determines that it needs to obtain the first duration.

[0155] In this embodiment, when the terminal device determines that it needs to obtain the first duration, it can be understood that: the terminal device determines that it needs to obtain the first duration from the network device.

[0156] Among them, there are various ways for the terminal device to determine that it needs to obtain the first duration, which will be described below in combination with Example a1 and Example a2.

[0157] Example a1: If the terminal device determines to trigger a random access procedure, it can determine that it needs to obtain a first duration. Among them, the terminal device determining to trigger a random access procedure may include: the terminal device sending a random access request to the network device or the terminal device determining that it will send a random access request to the network device. The random access request may be Message 1 (Msg1) in a four-step random access procedure or may also be Message A (MsgA) in a two-step random access procedure.

[0158] Example a2: If the terminal device determines to trigger a random access procedure and there is no available first duration and / or the terminal device has no positioning capability, it can determine that it needs to obtain a first duration. Among them, (1) no available first duration can also be referred to as no effective first duration. No available first duration may include that the first duration obtained by the terminal device last time has expired. For example, after the terminal device obtains the first duration, it can start a timer. If the timer times out, it means that the first duration has expired; the duration of the timer can be indicated by the network device. For example, the network device can indicate the duration of the timer through a system message. Or, no available first duration may also include that the terminal device has not obtained the first duration yet. (2) The terminal device having no positioning capability can be understood as that the terminal device is unable to obtain relevant information (such as the distance between a satellite and a ground reference point) based on its own positioning capability to determine the first duration.

[0159] It should be noted that there can be multiple events triggering the random access process. For example: (1) When the terminal device makes an initial access and establishes a radio connection when transitioning from the radio resource control (RRC) idle (RRC_IDLE) state to the RRC connected (RRC_CONNECTED) state; (2) The RRC connection re - establishment procedure; (3) Handover; (4) When downlink data arrives in the RRC_CONNECTED state (and an acknowledgement (ACK) / negative acknowledgement (NACK) needs to be sent back at this time), and the uplink is in an "out - of - sync" state; (5) When uplink data arrives in the RRC_CONNECTED state (such as when a measurement report needs to be reported or user data needs to be sent), and the uplink is in an "out - of - sync" state or there is no available physical uplink control channel (PUCCH) resource for scheduling request (SR) transmission (at this time, a terminal device allowed to perform uplink synchronization can use the random access channel (RACH) to replace the SR). Another example: (1) When uplink (UL) data arrives in the Inactive state, and the uplink is in an "out - of - sync" state at this time; (2) When downlink (DL) data arrives in the Inactive state, and the uplink is in an "out - of - sync" state at this time; (3) Requesting On - demand system information (SI) (in a 5G communication system, system information is divided into two categories: minimum SI and On - demand SI, where minimum SI is required to be received by all terminal devices, and On - demand SI can be requested according to the needs of the terminal device itself); (4) Beam failure recovery (BFR). The triggering events or reasons for the random access process described in Example a1 and Example a2 above do not include system message requests (such as On - demand system message requests) and beam failure recovery.

[0160] Step 403: The terminal device receives the system message and obtains (or determines) the first duration.

[0161] Exemplarily, the terminal device can read SIBX to obtain the first duration.

[0162] In a possible implementation, after the terminal device determines that it needs to obtain a first duration (for example, the terminal device determines to trigger a random access procedure), it can immediately receive the system message to obtain the first duration, or it can be ready to receive the system message at the nearest system message sending moment, or it can receive the system message from the network device within the same system message change period or the same frame or the same subframe or the same time slot or the same sub-slot as the triggered random access procedure. For example, refer to Figure 4b As shown, the terminal device determines to trigger a random access procedure at time t, and time t is located in change period 2. Furthermore, the terminal device can receive the system message within the same change period (i.e., change period 2).

[0163] It can be understood that since the terminal device's determination to trigger a random access procedure can include: the terminal device sends a random access request to the network device or the terminal device determines that it will send a random access request to the network device. Therefore, the terminal device can receive the system message to obtain the first duration after sending the random access request; or, it can also receive the system message to obtain the first duration before sending the random access request; or, sending the random access request and receiving the system message can be executed simultaneously, without specific limitation.

[0164] Step 404, the terminal device determines a timing advance according to the first duration, and this timing advance is used for communication between the terminal device and the network device. For example, the terminal device can send an uplink signal to the network device according to this timing advance.

[0165] Exemplarily, the terminal device can obtain a second duration, and then determine the timing advance according to the first duration and the second duration. There are various ways for the terminal device to obtain the second duration, which will be described below in combination with Example b1 and Example b2.

[0166] Example b1, the terminal device can receive a random access response from the network device, and the random access response is used to indicate the second duration.

[0167] Example b2, the terminal device can receive a random access response from the network device, and the random access response is used to indicate a fourth duration; further, the terminal device can also receive an adjustment value of the fourth duration from the network device, and determine the second duration according to the fourth duration and the adjustment value. The adjustment value can be carried in the MAC CE from the network device or other possible messages.

[0168] In this example, considering the mobility of the terminal device, the fourth duration indicated by the random access response may be different from the current UE specific TA due to reasons such as the movement of the terminal device. Therefore, after the network device sends a random access response to the terminal device, if it is determined that the fourth duration is different from the current UE specific TA, an adjustment value may be sent to the terminal device, so that the terminal device can obtain the current UE specific TA (i.e., the second duration) based on the fourth duration and the adjustment value. In this way, on the one hand, the accuracy of the UE specific TA can be effectively ensured, and on the other hand, since the network device can send an adjustment value to the terminal device without re-sending the UE specific TA, the transmission resources can be effectively saved.

[0169] It should be noted that there are various ways for the random access response to indicate the second duration (or the fourth duration). For example, the second duration is included in the random access response, or information for indicating the second duration (such as an index of the second duration) is included in the random access response, and no specific limitation is made. Exemplarily, the timing advance command in the random access response of the PLMN can be used to indicate the second duration (or the fourth duration).

[0170] By adopting the above method, when the terminal device determines that it needs to obtain the first duration, it reads the system message to obtain the first duration, which can effectively avoid the terminal device from frequently reading the system message and reduce the power consumption of the terminal device.

[0171] Embodiment 2

[0172] In Embodiment 2, a possible implementation of the communication method will be described based on the above Solution 2.

[0173] Figure 5 For the communication method provided in Embodiment 2 of this application, the corresponding flowchart is as Figure 5 shown, including:

[0174] Step 501, the network device sends auxiliary parameters to the terminal device.

[0175] Correspondingly, in Step 502, the terminal device receives the auxiliary parameters from the network device.

[0176] Here, the auxiliary parameters may include various possible information for determining the first duration, which will be described below in combination with Example c1 and Example c2.

[0177] Example c1, the auxiliary parameters include the position information of the ground reference point, or the auxiliary parameters include the position information of the ground reference point and the position information of the network device. For example, when the embodiments of this application are applied to Figure 1bWhen applied to the scenarios illustrated, the auxiliary parameters may include the location information of the ground reference point; when the embodiments of the present application are applied to Figure 1c the scenarios illustrated, the auxiliary parameters may include the location information of the ground reference point and the location information of the network device.

[0178] Example c2, the auxiliary parameters include at least one of the following: the initial value of the first duration (or the index of the initial value), the time information corresponding to the initial value, and the change rate of the first duration.

[0179] Exemplarily, (1) the initial value of the first duration may be an absolute time quantity. When the auxiliary parameters include the index of the initial value, the terminal device may determine the corresponding initial value according to the index, for example, obtain the corresponding initial value by looking up the table through the index. (2) The time corresponding to the initial value may be a moment in absolute time (such as coordinated universal time (UTC) or global positioning system (GPS) time). Taking UTC timekeeping as an example, the time corresponding to the initial value may be X1 year X2 month X3 day X4 hour X5 minute X6 second X7 millisecond. In the embodiments of the present application, the time accuracy is not limited, for example, it may be further accurate to microseconds or nanoseconds. Alternatively, the time corresponding to the initial value may also be a certain system frame boundary, a certain time slot boundary, a certain micro time slot boundary, a certain subframe boundary, etc. (3) The change rate of the first duration may be a rate value that changes with time, or may also be a step value that changes with time.

[0180] In the embodiments of the present application, there are various ways for the network device to send the auxiliary parameters to the terminal device. For example, the network device may send a system message to the terminal device, and the system message includes the auxiliary parameters.

[0181] Step 503, the terminal device determines the first duration according to the auxiliary parameters.

[0182] It can be understood that, for the different contents included in the auxiliary parameters sent by the network device, the ways for the terminal device to determine the first duration according to the auxiliary parameters are also different. The following respectively describes the possible implementations for the terminal device to determine the first duration according to the auxiliary parameters for the above Example c1 and Example c2.

[0183] (1) For Example c1

[0184] The terminal device can also obtain the position information of the satellite, and then determine the first duration according to the position information of the satellite and the auxiliary parameters. There are various ways for the terminal device to obtain the position information of the satellite. For example, the terminal device can obtain the satellite ephemeris, and then determine the position information of the satellite according to the satellite ephemeris. The satellite ephemeris includes the position information and orbital behavior information of celestial bodies such as satellites, and can be used to calculate, predict, depict, and track the running states of flying objects (such as satellites), such as time, position, and speed. The satellite ephemeris can express the precise parameters of flying objects such as celestial bodies, satellites, spacecraft, missiles, and space debris.

[0185] Among them, there are various ways for the terminal device to obtain the satellite ephemeris. In one possible way, the terminal device can obtain the satellite ephemeris from a network device or a core network device. For example, the terminal device receives a system message from the network device, and the system message includes the satellite ephemeris; or, the terminal device receives a non-access stratum (NAS) message from the core network device, and the NAS message includes the satellite ephemeris. In another possible way, the satellite ephemeris can be pre-configured. For example, the satellite ephemeris can be stored in the Subscriber Identity Module (SIM) card of the terminal device, and then the terminal device can obtain the satellite ephemeris from the SIM card.

[0186] Further, when the auxiliary parameter includes the position information of the ground reference point, the terminal device can determine the distance (i.e., d0) between the satellite and the ground reference point according to the position information of the satellite and the position information of the ground reference point, and then can determine the first duration; when the auxiliary parameter includes the position information of the ground reference point and the position information of the network device, the terminal device can determine the distance (i.e., d0) between the satellite and the ground reference point according to the position information of the satellite and the position information of the ground reference point, and determine the distance (i.e., d0_F) between the satellite and the network device according to the position information of the satellite and the position information of the network device, and then can determine the first duration.

[0187] (2) For example c2

[0188] In this example, the auxiliary parameter and the first duration satisfy a certain calculation relationship, such as a functional relationship, and this calculation relationship can be determined in advance. Further, the terminal device can determine the first duration according to the auxiliary parameter.

[0189] Taking the auxiliary parameters including the initial value of the first duration, the time information corresponding to the initial value, and the change rate of the first duration as an example. For instance, the initial value of the first duration is TA0, the corresponding time of the initial value is t0, the change rate of the first duration is k, and the current time is t1. Then the terminal device can calculate the first duration at the current time according to the function F(TA0, k, t0) of the initial value of the first duration, the time corresponding to the initial value, and the change rate of the first duration. For example, F(TA0, k, t0) = TA0 + k * (t1 - t0).

[0190] In an alternative solution, if the terminal device determines that it needs to obtain the first duration, it can determine the first duration according to the auxiliary parameters. Here, the terminal device determines that it needs to obtain the first duration, which can be understood as: the terminal device determines that it needs to determine the first duration according to the auxiliary parameters. There are various ways for the terminal device to determine that it needs to obtain the first duration. For example, when the terminal device determines to trigger the random access process, reference can be made to the description in Embodiment 1.

[0191] Step 504, the terminal device determines the timing advance according to the first duration.

[0192] Exemplarily, the implementation of step 504 can refer to step 404 in Embodiment 1 and will not be elaborated here.

[0193] Using the above method, the terminal device can determine the first duration according to the auxiliary parameters. Compared with the method of the terminal device frequently reading the system message to obtain the first duration, it can reduce the power consumption of the terminal device. Moreover, when the auxiliary parameters include the initial value of the first duration, the time information corresponding to the initial value, and the change rate of the first duration, since the terminal device does not need to obtain the satellite ephemeris and the bit overhead required for the initial value of the first duration, the time information corresponding to the initial value, and the change rate of the first duration is small, it can effectively save transmission resources.

[0194] Embodiment 3

[0195] In Embodiment 3, a possible implementation of the communication method will be described based on the above Solution 3.

[0196] Figure 6a For the communication method provided in Embodiment 3 of this application, the corresponding process schematic diagram is as Figure 6a shown, including:

[0197] Step 601, the first network device determines the change period of the first system message.

[0198] Here, the first system message can be used to indicate the first duration (referred to as common TA1 for ease of description), and common TA1 is used to determine the first timing advance, and the first timing advance is used for communication between the terminal device and the first network device.

[0199] Exemplarily, the first system message may also be used to indicate one or more other common TAs. For example, the first system message may also be used to indicate a third duration (referred to as common TA2), and common TA2 is used to determine a second timing advance, and the second timing advance is used for communication between the terminal device and the second network device. Among them, the first network device may be the serving network device of the terminal device, and the second network device is the candidate serving network device (or the next serving network device) of the terminal device. It can be understood that in the embodiments of the present application, taking the first system message being used to indicate common TA1 and common TA2 as an example, in other possible embodiments, when the terminal device also has other candidate serving network devices, the first system message may also carry other common TAs. Due to the mobility of the terminal device, the terminal device may move from the coverage area of one network device to the coverage area of another network device. In the embodiments of the present application, the common TA of the candidate serving network device is transmitted through the first system message, so as to effectively ensure the continuity of the service.

[0200] Exemplarily, the first system message may include a first system information block, and the first system information block may be a newly defined system information block, such as SIB X, and specific details may refer to the description in Embodiment 1 above.

[0201] Exemplarily, the change period of the first system message is different from the change period of the second system message. The second system message comes from the first network device, and the second system message may be used to carry information other than the information carried by the first system message. For example, the change period of the first system message may be less than the change period of the second system message. See Figure 6b shown for an example of the change period of the first system message and the change period of the second system message.

[0202] Step 602, the first network device sends indication information 1 to the terminal device, and the indication information 1 is used to indicate the change period of the first system message.

[0203] Correspondingly, in step 603, the terminal device receives the indication information 1 from the first network device and determines the change period of the first system message.

[0204] Step 604, the terminal device receives the first system message from the first network device according to the change period of the first system message.

[0205] Exemplarily, there may be multiple ways for the terminal device to receive the first system message according to the change period of the first system message. Two possible ways are described below in combination with Implementation Manner 1 and Implementation Manner 2.

[0206] (1) Implementation Manner 1

[0207] The terminal device may receive the first system message from the first network device within each change period of the first system message. For example, as shown in Figure 6b As shown, the terminal device may receive the first system message at the start boundary of each change period. For example, it may receive the first system message 1 at the start boundary of change period 0, receive the first system message 3 at the start boundary of change period 1, receive the first system message 5 at the start boundary of change period 2, and so on.

[0208] It can be understood that the first system message may be transmitted once or multiple times within each change period. When the terminal device successfully receives the first system message once within a certain change period, it may no longer receive other first system messages within that change period. For example, when the terminal device successfully receives the first system message 1 within change period 0, it may no longer receive the first system message 2.

[0209] (2) Implementation method 2

[0210] If the terminal device determines that it needs to obtain the first duration, it may receive the first system message from the first network device according to the change period of the first system message. Among them, there are various ways for the terminal device to determine that it needs to obtain the first duration. For example, if the terminal device determines that a random access process is triggered, it determines that it needs to obtain the first duration, which can be referred to the description in Embodiment 1; or, the terminal device receives indication information 2 from the first network device, and the indication information 2 is used to indicate that the first system message has changed, then it determines that it needs to obtain the first duration.

[0211] Furthermore, the terminal device may also receive the initial value of the first duration sent by the network device. For example, the network device may send the initial value of the first duration to the terminal device through the second system message.

[0212] Among them, there are various ways for the network device to send the indication information 2 to the terminal device. For example, the network device can send the indication information 2 to the terminal device through dedicated signaling, and the dedicated signaling can be downlink control information (DCI) (referred to as DCI-1), MAC CE, and specific limitations are not made. Taking the dedicated signaling as DCI-1 as an example, the network device can also send PDCCH configuration information to the terminal device. The PDCCH configuration information can be used to monitor DCI-1. For example, the PDCCH configuration information can include a search space and a control resource set associated with the search space, and can also include a radio network temporary identity (RNTI) used for scrambling DCI-1. Exemplarily, the network device can send the initial value of the first duration and the PDCCH configuration information through the same message. For example, the initial value of the first duration and the PDCCH configuration information are sent through the second system message; or, the initial value of the first duration and the PDCCH configuration information can also be sent through different messages.

[0213] In the embodiments of the present application, there are various ways for the indication information 2 to indicate that the first system message has changed. Some possible implementations are described below in combination with Example d1 and Example d2.

[0214] In Example d1, the indication information 2 can include 1 bit. When the value of this bit is 1, it means that the first system message has changed. When the value of this bit is 0, it means that the first system message has not changed.

[0215] In Example d2, when the first system message is used to indicate common TA1 and common TA2, the indication information 2 indicating that the first system message has changed can include: the indication information 2 indicating that common TA1 has changed, and / or the indication information 2 indicating that common TA2 has changed.

[0216] In this case, the indication information 2 can indicate that common TA1 has changed and / or common TA2 has changed in the form of a bitmap. For example, the indication information 2 includes two bits, and each bit corresponds to a common TA. For example, the network device and the terminal device can pre-agree on the common TA corresponding to each bit in the indication information 2. Taking the first bit corresponding to common TA1 and the second bit corresponding to common TA2 as an example, when the value of the first bit is 1, it means that common TA1 has changed. When the value of the first bit is 0, it means that common TA1 has not changed. The same applies to the second bit.

[0217] Further, when the indication information 2 indicates that the common TA1 has changed, the terminal device may receive the first system message to obtain the common TA1.

[0218] In Implementation 2, there may be multiple ways for the terminal device to receive the first system message from the first network device. Some possible implementations are described below in conjunction with Scenario 1 and Scenario 2.

[0219] (1) Scenario 1

[0220] After receiving the indication information 2, the terminal device may immediately receive the first system message to obtain the first duration, or it may be ready to receive the first system message at the nearest first system message transmission time, or it may receive the first system message from the network device within the same change period or the same frame or the same subframe or the same time slot or the same sub-slot as the indication information 2. For example, as shown in Figure 6c As shown, the indication information 2 is located in the change period 2. Then, after receiving the indication information 2, the terminal device may receive the first system message within the same change period (i.e., change period 2).

[0221] (2) Scenario 2

[0222] After receiving the indication information 2, the terminal device may receive the first system message at the first moment to obtain the first duration. Among them, there are multiple ways for the terminal device to determine the first moment. In one example, the first moment may be predefined by the protocol. For example, the first moment may be the end moment of the time domain resource carrying the indication information 2 closest to the frame boundary or the subframe boundary or the time slot boundary.

[0223] In another example, the network device may send the indication information 3 to the terminal device. The indication information 3 may be used to indicate the first moment. Then, the network device may determine the first moment according to the indication information 3. Among them, the indication information 3 may be included in the indication information 2, or the indication information 3 and the indication information 2 may be sent through the same message, which is not specifically limited. By adopting this method, the network device is used to indicate the first moment, which can effectively ensure that the terminal device obtains the first duration through the first system message and avoid the terminal device having to continuously detect the first system message for a long time.

[0224] In this example, there are multiple ways for the indication information 3 to indicate the first moment. For example, in one possible indication method, the indication information 3 may include the time information of the first moment. For instance, if the first moment is a moment in absolute timekeeping, taking UTC timekeeping as an example, if the first moment is X1 hours X2 minutes X3 seconds X4 milliseconds X5 microseconds, then the indication information 3 may include the values of X1, X2, X3, X4, and X5. In another possible indication method, the indication information 3 can be used to indicate the first duration, and the first duration can be understood as a time offset; based on the end moment of the time domain resource carrying the indication information 2, then adding the first duration to the end moment of the time domain resource carrying the indication information 2 can obtain the first moment; that is to say, the first duration can be the duration between the end moment of the time domain resource carrying the indication information 2 and the first moment, or the first duration is the time offset of the first moment relative to the end moment of the time domain resource carrying the indication information 2. The unit of the first duration can be a time unit in absolute timekeeping, such as seconds, milliseconds, microseconds, or nanoseconds, etc.; or it can also be time slots, micro time slots, sub - frames, etc.; or it can also be other possible time units, which are not specifically limited.

[0225] Step 605, the terminal device determines the timing advance according to the first duration.

[0226] Exemplarily, for the implementation of step 605, reference can be made to step 404 in Embodiment 1, which will not be elaborated here.

[0227] Using the above - mentioned method, since the network device designs a new change period for the first system message, the terminal device can read the first system message according to the change period of the first system message and read the second system message according to the change period of the second system message, and the two do not affect each other. For example, when the first duration carried by the first system message changes while the information carried by the second system message remains unchanged, the terminal device can read the first system message without reading the unnecessary second system message, thereby effectively reducing the energy consumption of the terminal device.

[0228] Furthermore, by setting different change periods for the system messages, such as setting different change periods for the first system message and the second system message, the network device can transmit parameters with different change frequencies through different system messages. For example, the change frequency of parameter a is relatively high, while the change frequency of parameter b is relatively low, then a smaller change period can be set for the system message transmitting parameter a, and a larger change period can be set for the system message transmitting parameter b, which is convenient for flexible configuration of parameters in NTN; at the same time, it also enables the terminal device to receive the changed parameters in a timely manner without reading unnecessary system messages.

[0229] Embodiment 4

[0230] In the fourth embodiment, a possible implementation of the communication method will be described based on the above solution four.

[0231] When the terminal device switches from the source network device to the target network device, since the common TA corresponding to the source network device and the target network device is different, the terminal device needs to know the common TA corresponding to the target network device.

[0232] Figure 7 The flowchart corresponding to the communication method provided in the fourth embodiment of this application is shown in Figure 7 as follows, including:

[0233] Step 701, the source network device determines that the terminal device needs to switch to the target network device.

[0234] Here, the source network device can receive the measurement report of the terminal device, and then determine that the terminal needs to switch to the target network device according to the measurement report. The specific implementation can refer to the existing solution.

[0235] Step 702, the source network device sends a handover request to the target network device.

[0236] Correspondingly, in step 703, the target network device receives the handover request and sends a handover response to the source network device. The handover response may include a first duration. The first duration is used to determine the timing advance, which is used for the communication between the terminal device and the target network device. That is, the first duration is the first duration corresponding to the target network device. Further, the handover response may also include the configuration information corresponding to the target network device. For example, the configuration information corresponding to the target network device may include random access resources (such as random access preambles).

[0237] Exemplarily, the source network device may configure one target network device for the terminal device, or may also configure multiple target network devices. When there are multiple target network devices, the source network device may send handover requests to the multiple target network devices respectively, and then obtain the first durations corresponding to the multiple target network devices respectively and the configuration information corresponding to the multiple target network devices.

[0238] Step 704, the source network device sends an RRC reconfiguration message to the terminal device, and the RRC reconfiguration message includes the first duration.

[0239] Correspondingly, in step 705, the terminal device receives the RRC reconfiguration message and then obtains the first duration.

[0240] Step 706, the terminal device determines the timing advance according to the first duration, and the timing advance is used for the communication between the terminal device and the target network device.

[0241] The following will separately describe some possible implementations of steps 704 to 706 in combination with Scenario 1 and Scenario 2.

[0242] Scenario 1

[0243] The source network device configures a target network device (such as target network device a) for the terminal device. The RRC reconfiguration message may include a first duration corresponding to target network device a. Accordingly, after receiving the RRC reconfiguration message, the terminal device can obtain the first duration corresponding to target network device a, and then determine timing advance 1, which is used for communication between the terminal device and target network device a.

[0244] Furthermore, the RRC reconfiguration message may also include configuration information and / or a handover command corresponding to target network device a. Among them, the configuration information corresponding to target network device a can be used for the terminal device to initiate random access to target network device a, and the handover command is used to instruct the terminal device to switch to target network device a.

[0245] Scenario 2

[0246] The source network device configures multiple target network devices (such as target network devices b1, b2, and b3) for the terminal device. The RRC reconfiguration message may include a first duration corresponding to target network device b1 (referred to as common TA1), a first duration corresponding to target network device b2 (referred to as common TA2), and a first duration corresponding to target network device b3 (referred to as common TA3). In this scenario, considering that the first durations corresponding to multiple target network devices may be the same (for example, in the case of transparent load, if the relay nodes corresponding to multiple target network devices are the same satellite, the first durations corresponding to multiple target network devices are the same), therefore, the RRC reconfiguration message may also include a unified first duration, which can be shared by multiple target network devices. Accordingly, after receiving the RRC reconfiguration message, the terminal device can select one of the multiple target network devices (such as the selected target network device is target network device b1), and obtain the first duration corresponding to target network device b1, and then determine timing advance 2, which is used for communication between the terminal device and target network device b1.

[0247] Exemplarily, there can be multiple ways for the terminal device to select one of the multiple target network devices. In one possible implementation, the terminal device can measure the multiple target network devices according to the measurement configuration information and select one of the target network devices based on the measurement results. For example, if the measurement result of a certain target network device meets the first condition, the terminal device can select this target network device; if the measurement results of two or more target network devices meet the first condition, the terminal device can select the target network device with the best measurement result, or the terminal device selects one of the target network devices whose measurement results meet the first condition according to a preset algorithm.

[0248] Among them, the measurement results can include reference signal receiving power (RSRP) and / or reference signal receiving quality (RSRQ). In one example, the best measurement result can mean that the RSRP is the maximum value, and / or the RSRQ is the maximum value; for example, the target network devices whose measurement results meet the first condition include target network device b1 and target network device b2. The measurement results obtained by the terminal device for target network device b1 include RSRP1 and RSRQ1, and the measurement results obtained by the terminal device for target network device b2 include RSRP2 and RSRQ2. Among them, RSRP1 is greater than RSRP2 and RSRQ1 is equal to RSRQ2. Furthermore, the target network device with the best measurement result can be target network device b1. In another example, the best measurement result can mean that the fluctuation of RSRP and / or RSRQ is the smallest within a preset time period. Among them, there can be multiple ways to measure the fluctuation of RSRP and / or RSRQ, and the embodiments of the present application do not limit this.

[0249] Exemplarily, the measurement configuration information can be predefined by the protocol, or can also be determined and sent to the terminal device by the source network device. For example, the source network device can send the measurement configuration information to the terminal device through an RRC reconfiguration message. The first condition can be predefined by the protocol, or can also be determined and sent to the terminal device by the source network device. For example, the source network device can send the first condition to the terminal device through an RRC reconfiguration message.

[0250] In one example, the source network device may send, to the terminal device, configuration information corresponding to multiple target network devices, a first duration corresponding to the multiple target network devices, measurement configuration information, a first condition, and a handover command (for instructing the terminal device to hand over to a selected target network device) through the same message. For example, the RRC reconfiguration message includes the configuration information corresponding to the multiple target network devices, the first duration corresponding to the multiple target network devices, the measurement configuration information, the first condition, and the handover command.

[0251] Exemplarily, for the implementation of step 706, reference may be made to step 404 in Embodiment 1. For example, the terminal device may receive a random access response from a target network device (such as target network device a or target network device b1), where the random access response includes a second duration, and then determine the timing advance according to the first duration and the second duration.

[0252] By using the above method, in a handover scenario, the source network device may send the first duration corresponding to the target network device to the terminal device. Further, since the source network device may send the first duration corresponding to the target network device and the random access resources allocated by the target network device for the terminal device through the same message (i.e., the RRC reconfiguration message) to the terminal device, transmission resources can be effectively saved.

[0253] It should be noted that for the handover scenario, the method described in Embodiment 4 above may be adopted, where the source network device sends the first duration corresponding to the target network device to the terminal device. Alternatively, the terminal device may also adaptively adopt the methods in Embodiment 1, Embodiment 2, or Embodiment 3 to obtain the first duration.

[0254] Embodiment 5

[0255] In Embodiment 5, a possible implementation of the communication method will be described based on the above Solution 5.

[0256] Figure 8 For the communication method provided in Embodiment 5 of this application, the corresponding flowchart is as Figure 8 shown, and it includes:

[0257] Step 801: The network device sends DCI-2 to the terminal device. DCI-2 is used to instruct the terminal device to trigger a random access process, and DCI-2 includes a first duration.

[0258] Exemplarily, when DCI-2 triggers a random access process for the terminal device, DCI-2 is referred to as a PDCCH order.

[0259] Exemplarily, DCI-2 may be DCI in multiple possible formats, such as DCI format 1A.

[0260] Step 802, the terminal device receives DCI-2 and obtains the first duration.

[0261] Step 803, the terminal device determines the timing advance according to the first duration.

[0262] Exemplarily, for the implementation of step 803, reference can be made to step 404 in Embodiment 1, which will not be elaborated here.

[0263] By adopting the above method, for the random access process triggered by PDCCH order, the network device can send the first duration to the terminal device through PDCCH order, so that the terminal device does not need to read the system message to obtain the first duration, effectively reducing the power consumption of the terminal device.

[0264] Regarding the above Embodiments 1 to 5, it should be noted that:

[0265] (1) Embodiments 1 to 5 can be separately implemented in different scenarios, or different embodiments among Embodiments 1 to 5 can be adaptively combined for implementation. Or, the solutions involved in different embodiments among Embodiments 1 to 5 can be adaptively combined for implementation.

[0266] (2) In the above description, the differences between different embodiments among Embodiments 1 to 5 are mainly described. For other content except the differences, Embodiments 1 to 5 can refer to each other.

[0267] (3) The step numbers in the flowcharts described in Embodiments 1 to 5 are only examples of the execution process and do not constitute a limitation on the execution order of the steps. There is no strict execution order for steps that have no timing dependence on each other in the embodiments of the present application.

[0268] (4) In the embodiments of the present application, message A includes information a (or message A is used to carry information a). It can be understood that message A includes information a itself, or it can also be understood that message A includes information b (such as the index of information a) for indicating information a.

[0269] (5) Considering that in the NTN scenario, in addition to the common TA described above, there may be other time parameters that change continuously with the movement of the satellite. The communication method provided in the embodiments of the present application can also be applicable to this time parameter, that is, the common TA in the embodiments of the present application can be adaptively replaced with this time parameter, or the terminal device can obtain this time parameter in the same way as obtaining the common TA. For example, this time parameter and the common TA can both be carried in SIB X.

[0270] Exemplarily, the time parameter may refer to a parameter related to the distance between the terminal device and the satellite. For example, it may be a time offset. For example, if the time parameter is the time offset of the round-trip delay (RTD), after the terminal device obtains the time parameter, it can update the previously obtained RTD. Or, if the time parameter is the time offset of the user plane (UP) offset / timer, after the terminal device obtains the time parameter, it can update the previously obtained UP offset / timer. Among them, there are various ways to update the previously obtained RTD or UP offset / timer according to the time parameter. For example, adding the time parameter to the previously obtained RTD or UP offset / timer to obtain the updated RTD or UP offset / timer. Among them, the value of the time parameter can be positive or negative.

[0271] Taking the time parameter as the time offset of the UP offset / timer as an example, the time unit of the time parameter may be the same as or different from the time unit of the UP offset / timer. When the time unit of the time parameter is different from the time unit of the UP offset / timer, the terminal device may first adjust the time unit of the time parameter to be consistent with the time unit of the UP offset / timer, and then update the UP offset / timer.

[0272] In the embodiments of this application, the UP timer may include at least one of the following: MAC layer timer, RLC layer timer, PDCP layer timer.

[0273] Among them, the MAC layer timer may include a discontinuous reception (DRX) related timer, a scheduling request (SR) related timer, a buffer status report (BSR) related timer, and a random access related timer.

[0274] Referring to Table 1 below, some possible examples of the DRX related timer are shown.

[0275] Table 1: Examples of DRX related timers

[0276]

[0277] Referring to Table 2 below, some possible examples of the SR related timer are shown.

[0278] Table 2: Examples of SR-related Timers

[0279] Name Description Unit of Measurement sr-ProhibitTimer SR Prohibition Timer Milliseconds / ms logicalChannelSR-DelayTimer Logical Channel SR Delay Timer Subframe

[0280] As shown in Table 3, some possible examples of BSR-related timers are provided.

[0281] Table 3: Examples of SR-related Timers

[0282] Name Description Unit of Measurement periodicBSR-Timer Periodic BSR Timer Subframe retxBSR-Timer Retransmission BSR Timer Subframe

[0283] As shown in Table 4, some possible examples of random access-related timers are provided.

[0284] Table 4: Examples of Random Access-related Timers

[0285] Name Description Unit of Measurement ra-ContentionResolutionTimer Contention Resolution Timer Subframe ra-ResponseWindow Random Access Response Window Size Slot

[0286] As shown in Table 5, some possible examples of RLC layer timers are provided.

[0287] Table 5: Examples of RLC layer Timers

[0288] Name Description Unit of Measurement T-PollRetransmit Polling Retransmission Timer Milliseconds / ms T-StatusProhibit Prohibited Status Report Timer Milliseconds / ms

[0289] As shown in Table 6, some possible examples of PDCP layer timers are provided.

[0290] Table 6: Examples of PDCP layer Timers

[0291] Name Description Unit of Measurement discardTimer Discard Timer Milliseconds / ms t-Reordering Reordering Timer Milliseconds / ms

[0292] It can be understood that some timer examples that the above-described UP timer may include. In other possible embodiments, the UP timer may further include other possible timers, such as the Data Inactivity Timer and the timeAlignmentTimer, which are not listed one by one here.

[0293] The above mainly introduces the solution provided by the embodiments of the present application from the perspective of the interaction between the network device and the terminal device. It can be understood that, in order to implement the above functions, the network device or the terminal device may include the corresponding hardware structure and / or software module for executing each function. Those skilled in the art should easily realize that, combining the units and algorithm steps of each example described in the embodiments disclosed herein, the embodiments of the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a certain function is executed in the way of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present application.

[0294] The embodiments of the present application can divide the terminal device and the network device into functional units according to the above method examples. For example, each functional unit can be divided corresponding to each function, or two or more functions can be integrated into one unit. The above integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0295] In the case of adopting an integrated unit, Figure 9 shows a possible exemplary block diagram of the device involved in the embodiments of the present application. As Figure 9 shown, the device 900 may include: a processing unit 902 and a communication unit 903. The processing unit 902 is used to control and manage the actions of the device 900. The communication unit 903 is used to support the communication between the device 900 and other devices. Optionally, the communication unit 903 is also called a transceiver unit, and may include a receiving unit and / or a transmitting unit, which are respectively used to perform receiving and transmitting operations. The device 900 may further include a storage unit 901, which is used to store the program code and / or data of the device 900.

[0296] The device 900 may be the terminal device in any of the above embodiments, or may also be a chip provided in the terminal device. The processing unit 902 may support the device 900 to execute the actions of the terminal device in the above method examples. Alternatively, the processing unit 902 mainly executes the internal actions of the terminal device in the method examples, and the communication unit 903 may support the communication between the device 900 and the network device.

[0297] In one embodiment, the processing unit 902 controls the communication unit 903 to execute: determining that a first duration needs to be obtained, determining the first duration, and determining a timing advance according to the first duration, where the timing advance is used for the communication between the terminal device and the network device.

[0298] In a possible design, the processing unit 902 is specifically used to: determine to trigger a random access process.

[0299] In a possible design, the processing unit 902 is specifically configured to: determine that there is no valid first duration for the terminal device.

[0300] In a possible design, the communication unit 903 is specifically configured to receive a system message from a network device, where the system message is used to carry the first duration; or, the processing unit 902 is specifically configured to determine the first duration according to a first auxiliary parameter; where the first auxiliary parameter includes the location information of a ground reference point, or, the first auxiliary parameter includes the location information of a ground reference point and the location information of a network device; or, the processing unit 902 is specifically configured to determine the first duration according to a second auxiliary parameter; where the second auxiliary parameter includes an initial value of the first duration, time information corresponding to the initial value, and a change rate of the first duration.

[0301] In a possible design, the processing unit 902 is further configured to obtain a second duration, and determine a timing advance according to the first duration and the second duration.

[0302] In a possible design, the communication unit 903 is further configured to: receive a random access response from a network device, where the random access response includes the second duration; or, receive a random access response from a network device, where the random access response includes a fourth duration; receive an adjustment value of the fourth duration from a network device, and determine the second duration according to the fourth duration and the adjustment value.

[0303] In another embodiment, the processing unit is configured to determine a first change period of a first system message, where the first system message is used to carry the first duration, the first duration is used to determine a first timing advance, and the first timing advance is used for communication between the terminal device and a first network device; the communication unit 903 is configured to receive the first system message from the first network device according to the first change period; where the first change period is different from a second change period of a second system message, and the second system message comes from the first network device.

[0304] In a possible design, the communication unit 903 is specifically configured to:

[0305] receive first indication information from a first network device, where the first indication information is used to indicate that the first system message has changed;

[0306] receive an updated first system message within the first change period where the first indication information is located.

[0307] In a possible design, the first system message is further used to carry a third duration, the third duration is used to determine a second timing advance, and the second timing advance is used for communication between the terminal device and a second network device.

[0308] In a possible design, the communication unit 903 is specifically configured to:

[0309] Receive second indication information from a first network device, where the second indication information is used to indicate that a first duration changes or is used to indicate that a third duration changes;

[0310] Receive a first system message within a first change period where the second indication information is located.

[0311] The apparatus 900 may be the network device in any of the above embodiments, or may also be a chip disposed in the network device. The processing unit 902 may support the apparatus 900 to perform the actions of the network device in the method examples above. Alternatively, the processing unit 902 mainly performs the internal actions of the network device in the method examples, and the communication unit 903 may support the communication between the apparatus 900 and the terminal device.

[0312] In one embodiment, the processing unit 902 is configured to determine an auxiliary parameter, where the auxiliary parameter includes the position of a ground reference point, or the auxiliary parameter includes the position of the ground reference point and the position of the network device, or the auxiliary parameter includes an initial value of a first duration, time information corresponding to the initial value, and a change rate of the first duration;

[0313] The communication unit 903 is configured to send the auxiliary parameter to the terminal device.

[0314] In a possible design, the communication unit 903 is further configured to send satellite ephemeris to the terminal device; where the network device is located on a satellite, or the satellite is a relay node for communication between the terminal device and the network device.

[0315] In yet another embodiment, the processing unit 902 is configured to determine a first change period of a first system message, where the first system message is used to carry a first duration, the first duration is used to determine a first timing advance, and the first timing advance is used for communication between the terminal device and the apparatus; the communication unit 903 is configured to send third indication information to the terminal device, where the third indication information is used to indicate the first change period; where the first change period is different from a second change period of a second system message, and the second system message comes from the apparatus.

[0316] In a possible design, the communication unit 903 is further configured to send first indication information to the terminal device, where the first indication information is used to indicate that the first system message changes.

[0317] In a possible design, the first system message is further used to carry a third duration, the third duration is used to determine a second timing advance, and the second timing advance is used for communication between the terminal device and a second network device.

[0318] In a possible design, the communication unit 903 is further configured to send second indication information to the terminal device, where the second indication information is used to indicate a change in the first duration or to indicate a change in the third duration.

[0319] It should be understood that the division of units in the above device is only a division of logical functions. In actual implementation, all or part of them can be integrated into a physical entity, or physically separated. And the units in the device can all be implemented in the form of software called by a processing element; they can also all be implemented in the form of hardware; or some units can be implemented in the form of software called by a processing element, and some units can be implemented in the form of hardware. For example, each unit can be a separately established processing element, or can be integrated in a certain chip of the device. In addition, it can also be stored in the memory in the form of a program, and the function of the unit is called and executed by a certain processing element of the device. In addition, all or part of these units can be integrated together or can be independently implemented. The processing element mentioned here can also be a processor, which can be an integrated circuit with signal processing capabilities. In the implementation process, each step of the above method or each of the above units can be implemented by the integrated logic circuit of the hardware in the processor element or in the form of software called by the processing element.

[0320] In an example, the units in any of the above devices can be one or more integrated circuits configured to implement the above method. For example: one or more Application Specific Integrated Circuits (ASICs), or one or more digital signal processors (DSPs), or one or more Field Programmable Gate Arrays (FPGAs), or a combination of at least two of these integrated circuit forms. Again, when the units in the device can be implemented in the form of a processing element scheduler, the processing element can be a processor, such as a general central processing unit (CPU), or other processors that can call programs. Again, these units can be integrated together and implemented in the form of a system-on-a-chip (SOC).

[0321] The above receiving unit is an interface circuit of the device for receiving signals from other devices. For example, when the device is implemented in the form of a chip, the receiving unit is the interface circuit of the chip for receiving signals from other chips or devices. The above sending unit is an interface circuit of the device for sending signals to other devices. For example, when the device is implemented in the form of a chip, the sending unit is the interface circuit of the chip for sending signals to other chips or devices.

[0322] Please refer to Figure 10 , which is a schematic structural diagram of a terminal device provided by an embodiment of the present application. It can be the terminal device in the above embodiments and is used to implement the operations of the terminal device in the above embodiments. As Figure 10 shown, the terminal device includes: an antenna 1010, a radio frequency part 1020, and a signal processing part 1030. The antenna 1010 is connected to the radio frequency part 1020. In the downlink direction, the radio frequency part 1020 receives the information sent by the network device through the antenna 1010 and sends the information sent by the network device to the signal processing part 1030 for processing. In the uplink direction, the signal processing part 1030 processes the information of the terminal device and sends it to the radio frequency part 1020. After processing the information of the terminal device, the radio frequency part 1020 sends it to the network device through the antenna 1010.

[0323] The signal processing part 1030 may include a modulation and demodulation subsystem for implementing the processing of each communication protocol layer of the data; it may also include a central processing subsystem for implementing the processing of the operating system and application layer of the terminal device; in addition, it may also include other subsystems, such as a multimedia subsystem, a peripheral subsystem, etc. The multimedia subsystem is used to implement the control of the camera, screen display, etc. of the terminal device, and the peripheral subsystem is used to implement the connection with other devices. The modulation and demodulation subsystem may be a separately provided chip.

[0324] The modulation and demodulation subsystem may include one or more processing elements 1031. For example, it includes a main control CPU and other integrated circuits. In addition, the modulation and demodulation subsystem may also include a storage element 1032 and an interface circuit 1033. The storage element 1032 is used to store data and programs, but the program for executing the method performed by the terminal device in the above method may not be stored in the storage element 1032, but in a memory outside the modulation and demodulation subsystem and is loaded and used by the modulation and demodulation subsystem when in use. The interface circuit 1033 is used to communicate with other subsystems.

[0325] The modulation and demodulation subsystem can be implemented by a chip, which includes at least one processing element and an interface circuit. The processing element is used to execute each step of any of the methods executed by the above terminal device, and the interface circuit is used to communicate with other devices. In one implementation, the units for implementing each step of the above method in the terminal device can be implemented in the form of a processing element scheduler. For example, a device for a terminal device includes a processing element and a storage element, and the processing element calls a program stored in the storage element to execute the method executed by the terminal device in the above method embodiments. The storage element can be a storage element on the same chip as the processing element, that is, an on-chip storage element.

[0326] In another implementation, the program for executing the method executed by the terminal device in the above method can be in a storage element on a different chip from the processing element, that is, an off-chip storage element. At this time, the processing element calls or loads the program from the off-chip storage element onto the on-chip storage element to call and execute the method executed by the terminal device in the above method embodiments.

[0327] In yet another implementation, the units for implementing each step of the above method in the terminal device can be one or more processing elements configured to be disposed on the modulation and demodulation subsystem. The processing elements here can be integrated circuits, such as: one or more ASICs, or one or more DSPs, or one or more FPGAs, or a combination of these types of integrated circuits. These integrated circuits can be integrated together to form a chip.

[0328] The units for implementing each step of the above method in the terminal device can be integrated together and implemented in the form of an SOC. The SOC chip is used to implement the above method. At least one processing element and a storage element can be integrated in the chip, and the method executed by the above terminal device is implemented in the form of the processing element calling the program stored in the storage element; or, at least one integrated circuit can be integrated in the chip to implement the method executed by the above terminal device; or, the above implementation methods can be combined, and the functions of some units are implemented in the form of the processing element calling a program, and the functions of some units are implemented in the form of an integrated circuit.

[0329] It can be seen that the device for the above terminal device can include at least one processing element and an interface circuit, where at least one processing element is used to execute any of the methods provided by the above method embodiments executed by the terminal device. The processing element can execute some or all of the steps executed by the terminal device in the first way: that is, by calling the program stored in the storage element; or in the second way: that is, by combining the integrated logic circuit in the processor element with instructions to execute some or all of the steps executed by the terminal device; of course, it can also combine the first way and the second way to execute some or all of the steps executed by the terminal device.

[0330] The processing element here is the same as described above and can be implemented by a processor. The functions of the processing element can be the same as those of the Figure 9 processing unit described therein. Exemplarily, the processing element can be a general-purpose processor, such as a CPU, or can also be one or more integrated circuits configured to implement the above methods, such as: one or more ASICs, or, one or more microprocessors DSPs, or, one or more FPGAs, etc., or a combination of at least two of these integrated circuit forms. The storage element can be implemented by a memory, and the functions of the storage element can be the same as those of the Figure 9 storage unit described therein. The storage element can be implemented by a memory, and the functions of the storage element can be the same as those of the Figure 9 storage unit described therein. The storage element can be a single memory or a collective term for multiple memories.

[0331] Figure 10 The terminal device shown can implement Figure 4a , Figure 5 , Figure 6a , Figure 7 or Figure 8 each process related to the terminal device in the method embodiments illustrated. Figure 10 The operations and / or functions of each module in the terminal device shown are respectively for implementing the corresponding processes in the above method embodiments. For details, reference can be made to the descriptions in the above method embodiments. To avoid repetition, the detailed descriptions are appropriately omitted here.

[0332] Please refer to Figure 11 , which is a schematic structural diagram of a network device provided in an embodiment of the present application. It is used to implement the operations of the network device in the above embodiments. As Figure 11 shown, the network device includes: an antenna 1101, a radio frequency device 1102, and a baseband device 1103. The antenna 1101 is connected to the radio frequency device 1102. In the uplink direction, the radio frequency device 1102 receives the information sent by the terminal device through the antenna 1101 and sends the information sent by the terminal device to the baseband device 1103 for processing. In the downlink direction, the baseband device 1103 processes the information of the terminal device and sends it to the radio frequency device 1102. After the radio frequency device 1102 processes the information of the terminal device, it is sent to the terminal device through the antenna 1101.

[0333] The baseband device 1103 may include one or more processing elements 11031. For example, it includes a main control CPU and other integrated circuits. In addition, the baseband device 1103 may also include a storage element 11032 and an interface 11033. The storage element 11032 is used to store programs and data. The interface 11033 is used to interact with the radio frequency device 1102. This interface is, for example, a common public radio interface (CPRI). The devices for the network device mentioned above may be located in the baseband device 1103. For example, the devices for the network device mentioned above may be chips on the baseband device 1103. This chip includes at least one processing element and an interface circuit. The processing element is used to execute each step of any of the methods executed by the above network device. The interface circuit is used to communicate with other devices. In one implementation, the units of the network device that implement each step of the above method may be implemented in the form of a processing element scheduler. For example, the devices for the network device include a processing element and a storage element. The processing element calls the program stored in the storage element to execute the method executed by the network device in the above method embodiment. The storage element may be a storage element on the same chip as the processing element, that is, an on-chip storage element, or a storage element on a different chip from the processing element, that is, an off-chip storage element.

[0334] In another implementation, the units of the network device that implement each step of the above method may be configured as one or more processing elements. These processing elements are provided on the baseband device. The processing elements here may be integrated circuits. For example: one or more ASICs, or one or more DSPs, or one or more FPGAs, or a combination of these types of integrated circuits. These integrated circuits may be integrated together to form a chip.

[0335] The units of the network device that implement each step of the above method may be integrated together and implemented in the form of a system-on-a-chip (SOC). For example, the baseband device includes this SOC chip for implementing the above method. At least one processing element and a storage element may be integrated in this chip. The method executed by the above network device is implemented in the form of the processing element calling the program stored in the storage element. Or, at least one integrated circuit may be integrated in this chip for implementing the method executed by the above network device. Or, the above implementation methods may be combined. The functions of some units are implemented in the form of the processing element calling a program, and the functions of some units are implemented in the form of an integrated circuit.

[0336] It can be seen that the above device for a network device may include at least one processing element and an interface circuit, where at least one processing element is used to execute any of the methods performed by the network device provided in the above method embodiments. The processing element may execute some or all of the steps performed by the network device in a first manner, that is, by calling a program stored in a storage element; or in a second manner, that is, by combining the integrated logic circuit in the processor element with instructions to execute some or all of the steps performed by the network device; of course, it is also possible to combine the first manner and the second manner to execute some or all of the steps performed by the above network device.

[0337] The processing element here is the same as the above description and can be implemented by a processor. The functions of the processing element can be the same as those of the Figure 9 processing unit described therein. Exemplarily, the processing element may be a general-purpose processor, such as a CPU, or may also be one or more integrated circuits configured to implement the above method, such as: one or more ASICs, or one or more microprocessors DSPs, or one or more FPGAs, etc., or a combination of at least two of these integrated circuit forms. The storage element can be implemented by a memory, and the functions of the storage element can be the same as those of the Figure 9 storage unit described therein. The storage element can be implemented by a memory, and the functions of the storage element can be the same as those of the Figure 9 storage unit described therein. The storage element can be a single memory or a collective term for multiple memories.

[0338] Figure 11 The network device shown can implement Figure 4a , Figure 5 , Figure 6a , Figure 7 or Figure 8 each process related to the network device in the method embodiments illustrated. Figure 11 The operations and / or functions of each module in the network device shown are respectively for implementing the corresponding processes in the above method embodiments. For details, reference can be made to the description in the above method embodiments. To avoid repetition, the detailed description is appropriately omitted here.

[0339] In each embodiment of the present application, if there is no special description and logical conflict, the terms and / or descriptions between different embodiments are consistent and can be mutually referred to. The technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationships.

[0340] In the implementation process, each step in the method provided in this embodiment can be completed by the integrated logic circuit of the hardware in the processor or the instructions in the form of software. The steps of the method disclosed in combination with the embodiments of the present application can be directly embodied as being executed and completed by the hardware processor, or executed and completed by the combination of the hardware and software modules in the processor.

[0341] It should be noted that the memory or storage unit in the embodiments of the present application can be a volatile memory or a non-volatile memory, or can include both volatile and non-volatile memories. Among them, the non-volatile memory can be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory can be a random access memory (RAM), which is used as an external cache. By way of example but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct rambus random access memory (DR RAM). It should be noted that the memory of the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0342] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are executed in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer program or instructions can be stored in a computer-readable storage medium or transmitted through the computer-readable storage medium. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server integrating one or more available media. The available medium can be a magnetic medium, such as a floppy disk, a hard disk, or a magnetic tape; it can also be an optical medium, such as a DVD; or it can be a semiconductor medium, such as a solid state disk (SSD).

[0343] In the embodiments of the present application, the various illustrative logical units and circuits described can be implemented or operate the described functions through the design of a general-purpose processor, a digital signal processor, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination of the above. The general-purpose processor can be a microprocessor. Optionally, the general-purpose processor can also be any conventional processor, controller, microcontroller, or state machine. The processor can also be implemented by a combination of computing devices, such as a digital signal processor and a microprocessor, multiple microprocessors, one or more microprocessors combined with a digital signal processor core, or any other similar configuration.

[0344] The steps of the methods or algorithms described in the embodiments of the present application can be directly embedded in hardware, software units executed by a processor, or a combination of the two. The software units can be stored in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium in the art. Exemplarily, the storage medium can be connected to the processor so that the processor can read information from the storage medium and write information to the storage medium. Optionally, the storage medium can also be integrated into the processor. The processor and the storage medium can be disposed in an ASIC, and the ASIC can be disposed in a terminal device. Optionally, the processor and the storage medium can also be disposed in different components of the terminal device.

[0345] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus, so that a series of operation steps are executed on the computer or other programmable apparatus to produce a computer-implemented process, thereby the instructions executed on the computer or other programmable apparatus provide steps for implementing the functions specified in one process or multiple processes in the flowchart and / or one block or multiple blocks in the block diagram.

[0346] Although the embodiments of the present application are described in conjunction with specific features, it is obvious that various modifications and combinations can be made thereto without departing from the spirit and scope of the embodiments of the present application. Accordingly, the present specification and the drawings are merely exemplary illustrations of the embodiments of the present application defined by the appended claims, and are considered to cover any and all modifications, variations, combinations or equivalents within the scope of the embodiments of the present application.

Claims

1. A communication method, characterized in that, The method is applicable to a terminal device or a chip of the terminal device, and the method includes: Receiving first durations corresponding to M candidate target network devices from a source network device, where M is an integer greater than or equal to 1; Determining a timing advance according to the first durations corresponding to the target network device, where the timing advance is used for communication between the terminal device and the target network device. If M is greater than 1, the target network device is determined according to measurement results of the M candidate target network devices. If M is equal to 1, the target network device is the candidate target network device; Wherein, the first duration corresponding to the target network device is used to characterize the distance between a satellite and a ground reference point, and the target network device is deployed on the satellite; or, the first duration is used to characterize the sum of the distance between the satellite and the ground reference point and the distance between the satellite and the target network device, and the satellite is used to forward signals transmitted between the terminal device and the target network device.

2. The method according to claim 1, wherein The first durations corresponding to the M candidate target network devices are carried in a Radio Resource Control (RRC) reconfiguration message from the source network device.

3. The method according to claim 2, characterized in that When M is equal to 1, the RRC reconfiguration message further includes configuration information and / or a handover command corresponding to the target network device; Wherein, the configuration information corresponding to the target network device is used for the terminal device to initiate random access to the target network device, and the handover command is used to instruct the terminal device to hand over to the target network device.

4. The method according to claim 1 or 2, characterized in that, When M is greater than 1, the method further includes: Obtaining measurement results of the M candidate target network devices; Determining the target network device from the M candidate target network devices according to the measurement results of the M candidate target network devices.

5. The method according to claim 4, wherein Obtaining the measurement results of the M candidate target network devices includes: Receiving measurement configuration information from the source network device; Measuring the M candidate target network devices according to the measurement configuration information to obtain the measurement results of the M candidate target network devices.

6. The method according to claim 5, characterized in that, The measurement configuration information is carried in an RRC reconfiguration message from the source network device.

7. The method according to any one of claims 4 to 6, characterized in that, The measurement results include Reference Signal Received Power (RSRP) and / or Reference Signal Received Quality (RSRQ).

8. The method according to claim 7, characterized in that, The RSRP of the target network device is greater than or equal to the RSRP of other candidate target network devices among the M candidate target network devices; and / or, The RSRQ of the target network device is greater than or equal to the RSRQ of other candidate target network devices among the M candidate target network devices.

9. The method according to any one of claims 1 to 8, characterized in that, Determining the timing advance according to the first duration includes: Obtaining a second duration; Determining the timing advance according to the first duration and the second duration.

10. The method according to claim 9, characterized in that, Obtaining the second duration includes: Receiving a random access response from the target network device, where the random access response includes an index of the second duration; or, Receiving a random access response from the target network device, where the random access response includes a fourth duration; and receiving an adjustment value of the fourth duration from the target network device, and determining the second duration according to the fourth duration and the adjustment value.

11. A communication method, characterized in that, The method is applicable to the source network device of the terminal device or the chip of the source network device, and the method includes: Obtaining a first duration corresponding to M candidate target network devices, where M is an integer greater than or equal to 1; Sending the first duration corresponding to the M candidate target network devices to the terminal device. If M is greater than 1, the target network device of the terminal device is determined according to the measurement results of the M candidate target network devices. If M is equal to 1, the target network device of the terminal device is the candidate target network device; The first duration corresponding to the target network device is used to determine a timing advance, and the timing advance is used for communication between the terminal device and the target network device; Wherein, the first duration corresponding to the target network device is used to represent the distance between the satellite and the ground reference point, and the target network device is deployed on the satellite; or, the first duration is used to represent the sum of the distance between the satellite and the ground reference point and the distance between the satellite and the target network device, and the satellite is used to forward the signal transmitted between the terminal device and the target network device.

12. The method according to claim 11, wherein The first duration corresponding to the M candidate target network devices is carried in a Radio Resource Control (RRC) reconfiguration message.

13. The method according to claim 12, wherein When M is equal to 1, the RRC reconfiguration message further includes the configuration information and / or handover command corresponding to the target network device; Wherein, the configuration information corresponding to the target network device is used for the terminal device to initiate random access to the target network device, and the handover command is used to instruct the terminal device to hand over to the target network device.

14. The method according to claim 11 or 12, characterized in that When M is greater than 1, the method further includes: Sending measurement configuration information to the terminal device, and the measurement configuration information is used to measure the M candidate target network devices.

15. The method according to claim 14, wherein The measurement configuration information is carried in an RRC reconfiguration message.

16. The method according to any one of claims 11 to 15, characterized in that, The method further includes: Determining that the terminal device needs to hand over to the target network device; Sending a handover request to the target network device; Receiving a handover response from the target network device, and the handover response includes the first duration corresponding to the target network device.

17. The method according to claim 16, wherein The handover response further includes the configuration information corresponding to the target network device, and the configuration information corresponding to the target network device is used for the terminal device to initiate random access to the target network device.

18. A communication method, characterized in that, The method is applicable to the terminal device or the chip of the terminal device, and the method includes: Obtaining a time parameter, where the time parameter is related to the distance between the terminal device and the satellite, and the network device is deployed on the satellite; or, the satellite is used to forward the signal transmitted between the terminal device and the network device; Updating a pre-obtained user plane timer according to the time parameter, and the user plane timer includes at least one of the following: drx-HARQ-RTT-TimerDL, drx-HARQ-RTT-TimerUL, or ra-ContentionResolutionTimer; Among them, drx-HARQ-RTT-TimerDL is used to indicate the shortest duration required to wait for a downlink Hybrid Automatic Repeat reQuest (HARQ) retransmission scheduling, drx-HARQ-RTT-TimerUL is used to indicate the shortest duration required to wait for an uplink HARQ retransmission scheduling, and ra-ContentionResolutionTimer is used to indicate a contention resolution timer.

19. The method according to claim 18, wherein The updating of the pre-acquired user plane timer according to the time parameter includes: Adding the time parameter to the basis of the pre-acquired user plane timer to obtain an updated user plane timer.

20. A communication device, characterized in that, It includes at least one processor and an interface circuit. Among them, the at least one processor is used to communicate with other devices through the interface circuit and execute the method according to any one of claims 1 to 19.

21. A computer-readable storage medium, characterized in that, It includes a program, and when the program runs on a processor, the method according to any one of claims 1 to 19 is executed.

22. A computer program product, characterized in that, When a computer reads and executes the computer program product, the method according to any one of claims 1 to 19 is executed.

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