Uplink frequency synchronization method, device and system and storage medium

Abstract

The invention provides an uplink frequency synchronization method, device and system and a storage medium, and the method comprises the steps: receiving at least two downlink signals, and enabling the transmission frequencies of the at least two downlink signals to be different; determining a Doppler frequency offset estimation value and a local oscillator frequency error estimation value according to the at least two downlink signals; determining an uplink sending frequency according to the Doppler frequency offset estimation value and the local oscillator frequency error estimation value; and transmitting the uplink signal on the uplink transmission frequency. The problem of how to realize uplink frequency synchronization under the condition of no GNSS information is solved, and the uplink frequency synchronization performance and the initial random access performance in a satellite communication scene are improved.

Description

Technical Field

[0001] This application relates to the field of communication technologies, and in particular, to an uplink frequency synchronization method, apparatus, system, and storage medium. Background Art

[0002] Satellite communication achieves global seamless coverage. In a satellite communication system, frequency offset pre-compensation is usually required before transmitting an uplink signal to complete uplink frequency synchronization. Among the existing technologies, 3GPP NR-NTN has a basic working assumption: the user equipment (UE) has the function of the Global Navigation Satellite System (GNSS). The UE can obtain its own location information based on GNSS measurements, and then estimate and pre-compensate the frequency offset, so as to perform accurate uplink transmission.

[0003] However, the working assumption that the UE has the GNSS function may not hold. For example, in order to save terminal costs, the UE may not have GNSS capabilities. Or, in some scenarios such as indoors, the UE may not receive GNSS signals. Or, in order to save terminal power consumption, even if the UE has GNSS capabilities, it may stop using the GNSS function. As a result, problems occur in actual communication applications, such as a reduction in the uplink data transmission rate, or even an uplink link interruption, or the UE cannot access the network.

[0004] Therefore, a new uplink frequency synchronization scheme is needed. Summary of the Invention

[0005] In view of this, embodiments of this specification provide an uplink frequency synchronization method, apparatus, system, and storage medium for achieving uplink frequency synchronization.

[0006] Embodiments of this specification provide the following technical solutions:

[0007] In a first aspect, embodiments of this specification provide an uplink frequency synchronization method applied to a terminal device. The method includes: receiving at least two downlink signals with different transmission frequencies; determining an estimated value of the Doppler frequency offset and an estimated value of the local oscillator frequency error according to the at least two downlink signals; determining an uplink transmission frequency according to the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error; and transmitting an uplink signal at the uplink transmission frequency.

[0008] By adopting the uplink frequency synchronization method provided in this application, the terminal device receives downlink signals with at least two different transmission frequencies, determines the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error, and then determines the uplink transmission frequency. On the one hand, when the terminal device does not have GNSS capabilities, or in some scenarios such as indoor scenarios where the terminal device may not receive GNSS signals, or in order to save terminal power consumption, even if the terminal device has GNSS capabilities but may stop using the GNSS function, etc., the terminal device measures or estimates the frequency offset by receiving downlink signals. On the other hand, by receiving downlink signals with multiple different transmission frequencies, the terminal device can respectively measure or estimate the Doppler frequency offset and the local oscillator frequency error, determine the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error, improve the accuracy of frequency offset estimation, and then compensate for the Doppler frequency offset and the local oscillator frequency error of the uplink signal respectively, determine the uplink transmission frequency, transmit the uplink signal at the uplink transmission frequency, complete the uplink frequency synchronization, improve the performance of uplink transmission or improve the performance of random access, avoid the reduction of the uplink data transmission rate, and avoid the interruption of the uplink communication link.

[0009] Combined with the first aspect, in a possible implementation manner, the at least two downlink signals include downlink synchronization signals and / or downlink reference signals. That is to say, the at least two downlink signals may include at least two downlink synchronization signals, or the at least two downlink signals include at least two downlink reference signals, or the at least two downlink signals include at least one downlink synchronization signal and at least one downlink reference signal.

[0010] In this implementation manner, the terminal device receives downlink synchronization signals with at least two different transmission frequencies, determines the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error, and then determines the uplink transmission frequency according to the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error, which can achieve initial uplink frequency synchronization and at least improve the performance of random access. Or, the terminal device receives at least two different transmission frequencies of downlink reference signals, or at least one downlink synchronization signal and at least one downlink reference signal, and can, after the terminal device enters the connected state, track and estimate the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error, improve the estimation accuracy, and then determine the uplink transmission frequency according to the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error, achieve the frequency synchronization of uplink transmission, and improve the performance of uplink transmission.

[0011] In combination with the first aspect, in a possible implementation manner, determining the Doppler frequency offset estimation value and the local oscillator frequency error estimation value according to the at least two downlink signals includes: determining the transmission frequencies of the at least two downlink signals; determining the Doppler frequency offset estimation value and the local oscillator frequency error estimation value according to the at least two downlink signals and the transmission frequencies of the at least two downlink signals.

[0012] In combination with the first aspect, in a possible implementation manner, the frequency interval between the transmission frequencies of the at least two downlink signals is predefined.

[0013] In this implementation manner, the terminal device receives downlink signals with at least two different transmission frequencies, and the frequency interval between the transmission frequencies of the two downlink signals is predefined, so as to further improve the accuracy of Doppler frequency offset and local oscillator frequency error estimation without additional signaling overhead.

[0014] In combination with the first aspect, in a possible implementation manner, the method further includes: receiving the transmission frequency indication information of the at least two downlink signals, where the transmission frequency indication information of the at least two downlink signals includes the frequency interval indication information of the transmission frequencies of the at least two downlink signals, or the transmission frequency indication information of the at least two downlink signals includes the frequency domain resource configuration information of at least one of the at least two downlink signals; determining the transmission frequencies of the at least two downlink signals according to the transmission frequency indication information of the at least two downlink signals.

[0015] In this implementation manner, the terminal device receives the transmission frequency indication information of the at least two downlink signals. On the one hand, it can further improve the accuracy of Doppler frequency offset and local oscillator frequency error estimation. On the other hand, it can realize flexible transmission of downlink signals and improve resource utilization.

[0016] In combination with the first aspect, in a possible implementation manner, the at least two downlink signals include at least one CD-SSB and at least one NCD-SSB, the transmission frequency indication information of the at least two downlink signals includes the frequency interval indication information of the transmission frequencies of the NCD-SSB and the CD-SSB, or the transmission frequency indication information of the at least two downlink signals includes the frequency domain resource configuration information of the NCD-SSB, and the transmission frequency indication information of the at least two downlink signals is included in the SIB1 / MIB corresponding to the CD-SSB.

[0017] In combination with the first aspect, in a possible implementation manner, the at least two downlink signals include at least two CD-SSBs.

[0018] In combination with the first aspect, in a possible implementation manner, the determining of the uplink transmission frequency according to the estimated Doppler frequency offset value and the estimated local oscillator frequency error includes: determining a Doppler frequency offset compensation value according to the estimated Doppler frequency offset value, where the Doppler frequency offset compensation value is the negative of the estimated Doppler frequency offset value; determining a local oscillator frequency error compensation value according to the estimated local oscillator frequency error value, where the local oscillator frequency error compensation value is the positive of the estimated local oscillator frequency error value; and determining the uplink transmission frequency according to the Doppler frequency offset compensation value and the local oscillator frequency error compensation value.

[0019] The method of the first aspect described above is applied to a terminal device, also known as a user equipment UE, a mobile station (MS), a mobile terminal (MT), a mobile device, a user unit, an access terminal device, or a terminal, etc., which represents any terminal device capable of wireless communication with a network or between user devices, and can be deployed on land, including indoor or outdoor, handheld, wearable or vehicle-mounted; it can also be deployed on water (such as a ship, etc.); it can also be deployed in the air (such as an airplane, a balloon, etc.). The terminal device can be a smart phone, a tablet computer, a computer with wireless transceiver function; it can also be a satellite communication module, which can be integrated into other devices, such as Internet of Things (IoT) devices, vehicle communication systems, etc.; it can also be a satellite phone, a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, a wireless terminal in a smart city, a wireless terminal in a smart home, a wireless terminal in self-driving, a wireless terminal in remote medical, a wireless terminal in a smart grid, a wireless terminal in transportation safety, a smart watch or a wearable device.

[0020] The embodiments of this specification can be applied to satellite communication, remote monitoring of Internet of Things (IoT) devices, indoor or GNSS signal restricted scenarios (such as indoor communication, urban canyon environment), low-power devices or low-cost terminals, initial cell search, random access process, and future 6G and satellite-ground integration scenarios.

[0021] In a second aspect, an embodiment of this specification provides an uplink frequency synchronization method, which is applied to a network device. The method includes: sending at least two downlink signals with different transmission frequencies, where the at least two downlink signals are used for a terminal device to determine an estimated value of the Doppler frequency offset and an estimated value of the local oscillator frequency error; receiving an uplink signal from the terminal device, where the uplink transmission frequency of the uplink signal is determined by the terminal device according to the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error.

[0022] By using the uplink frequency synchronization method provided in this application, the network device sends at least two downlink signals with different transmission frequencies, which are used for the terminal device to determine an estimated value of the Doppler frequency offset and an estimated value of the local oscillator frequency error, and then determine the uplink transmission frequency according to the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error. On the one hand, when the terminal device does not have GNSS capabilities, or in some scenarios such as indoor scenarios where the terminal device may not receive GNSS signals, or in order to save terminal power consumption, the terminal device may stop using the GNSS function even if it has GNSS capabilities, etc., the network device sends downlink signals for the terminal device to measure or estimate the frequency offset. On the other hand, the network device sends multiple downlink signals with different transmission frequencies for the terminal device to measure or estimate the Doppler frequency offset and the local oscillator frequency error respectively, determine the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error, improve the accuracy of the frequency offset estimation, and then compensate for the Doppler frequency offset and the local oscillator frequency error of the uplink signal respectively, determine the uplink transmission frequency, send the uplink signal at the uplink transmission frequency, complete the uplink frequency synchronization, improve the performance of the uplink transmission or improve the performance of random access, avoid the reduction of the uplink data transmission rate, and avoid the interruption of the uplink communication link.

[0023] In combination with the second aspect, in a possible implementation, the at least two downlink signals include downlink synchronization signals and / or downlink reference signals. That is to say, the at least two downlink signals may include at least two downlink synchronization signals, or the at least two downlink signals include at least two downlink reference signals, or the at least two downlink signals include at least one downlink synchronization signal and at least one downlink reference signal.

[0024] In this implementation manner, the network device transmits downlink synchronization signals with at least two different transmission frequencies, which are used for the terminal device to determine the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error, and then determine the uplink transmission frequency according to the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error, so as to achieve initial uplink frequency synchronization and at least improve the performance of random access. Alternatively, the network device transmits downlink reference signals with at least two different transmission frequencies, or at least one downlink synchronization signal and at least one downlink reference signal, which are used for the terminal device to track and estimate the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error after entering the connected state, improve the estimation accuracy, and then determine the uplink transmission frequency according to the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error, so as to achieve frequency synchronization of uplink transmission and improve the performance of uplink transmission.

[0025] Combined with the second aspect, in a possible implementation manner, the at least two downlink signals are used for the terminal device to determine the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error, including: the terminal device determines the transmission frequencies of the at least two downlink signals; the terminal device determines the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error according to the at least two downlink signals and the transmission frequencies of the at least two downlink signals.

[0026] Combined with the second aspect, in a possible implementation manner, the frequency interval between the transmission frequencies of the at least two downlink signals is predefined.

[0027] In this implementation manner, the frequency interval between the transmission frequencies of the two downlink signals is predefined, and the network device side can improve the estimation accuracy of the Doppler frequency offset of the terminal device and the local oscillator frequency error without additional signaling overhead.

[0028] Combined with the second aspect, in a possible implementation manner, the method further includes: transmitting the transmission frequency indication information of the at least two downlink signals, where the transmission frequency indication information of the at least two downlink signals includes the frequency interval indication information of the transmission frequencies of the at least two downlink signals, or the transmission frequency indication information of the at least two downlink signals includes the frequency domain resource configuration information of at least one of the at least two downlink signals; the transmission frequency indication information of the at least two downlink signals is used for the terminal device to determine the transmission frequencies of the at least two downlink signals.

[0029] In this implementation manner, the network device transmits the transmission frequency indication information of at least two downlink signals to the terminal device. On the one hand, it can further improve the estimation accuracy of the Doppler frequency offset and the local oscillator frequency error of the terminal device. On the other hand, the network device can flexibly transmit downlink signals and improve resource utilization.

[0030] In combination with the second aspect, in a possible implementation, the at least two downlink signals include at least one CD-SSB and at least one NCD-SSB, and the transmission frequency indication information of the at least two downlink signals includes frequency interval indication information of the transmission frequencies of the NCD-SSB and the CD-SSB, or the transmission frequency indication information of the at least two downlink signals includes frequency domain resource configuration information of the NCD-SSB, and the transmission frequency indication information of the at least two downlink signals is included in the SIB1 / MIB corresponding to the CD-SSB.

[0031] In combination with the second aspect, in a possible implementation, the at least two downlink signals include at least two CD-SSB.

[0032] In combination with the second aspect, in a possible implementation, the uplink transmission frequency of the uplink signal is determined by the terminal device according to the estimated Doppler frequency offset value and the estimated local oscillator frequency error value, including: the terminal device determines a Doppler frequency offset compensation value according to the estimated Doppler frequency offset value, and the Doppler frequency offset compensation value is a negative estimated Doppler frequency offset value; the terminal device determines a local oscillator frequency error compensation value according to the estimated local oscillator frequency error value, and the local oscillator frequency error compensation value is a positive estimated local oscillator frequency error value; the terminal device determines the uplink transmission frequency according to the Doppler frequency offset compensation value and the local oscillator frequency error compensation value.

[0033] The method of the second aspect described above is applied to a network device, which represents an entity or node that communicates with a user equipment and provides services for the user equipment, and is used for signal transmission, processing, management, etc. The network device may be any satellite base station with wireless transceiver functions in a satellite network. The satellite base station may be a macro base station, a micro base station, a pico base station, a small station, a relay station, a balloon station, a drone station, etc., including but not limited to a new radio (NR) base station (gNodeB or gNB) or a transmission receiving point (TRP) carried on a satellite, a base station evolved by 3GPP in the future, a wireless relay node, a wireless backhaul node, etc. The network device may communicate with the user equipment, or may communicate with the user equipment through a relay station.

[0034] The embodiments of this specification can be applied to satellite communication, remote monitoring of Internet of Things (IoT) devices, indoor or GNSS signal restricted scenarios (such as indoor communication, urban canyon environment), low-power devices or low-cost terminals, initial cell search, random access process, and future 6G and space-ground integration scenarios.

[0035] In a third aspect, the embodiments of this specification further provide a communication device, which includes at least one processor and a memory. The processor and the memory are coupled. The memory stores program instructions. When the program instructions stored in the memory are executed by the processor, the methods in the above first aspect or any possible implementation manner in the first aspect, or the methods in the above second aspect or any possible implementation manner in the second aspect are executed.

[0036] In a fourth aspect, the embodiments of this specification further provide a communication device, which includes at least one processor and an interface circuit. The at least one processor is configured to execute the methods in the above first aspect or any possible implementation manner in the first aspect, or the methods in the above second aspect or any possible implementation manner in the second aspect.

[0037] In a fifth aspect, the embodiments of this specification provide a communication device, which includes any one of the above-provided communication devices.

[0038] In a sixth aspect, the embodiments of this specification provide a communication system, including: a terminal device and a network device; wherein, the terminal device is configured to execute the methods in the above first aspect or any possible implementation manner in the first aspect; the network device is configured to execute the methods in the above second aspect or any possible implementation manner in the second aspect.

[0039] In a seventh aspect, the embodiments of this specification further provide a computer program product, which includes a computer program. When the computer program is executed by a processor, it is configured to execute the methods in the above first aspect or any possible implementation manner in the first aspect, or the methods in the above second aspect or any possible implementation manner in the second aspect.

[0040] In an eighth aspect, the embodiments of this specification further provide a computer-readable storage medium, in which a computer program is stored. When the computer program is executed, it is configured to execute the methods in the above first aspect or any possible implementation manner in the first aspect, or the methods in the above second aspect or any possible implementation manner in the second aspect.

[0041] In a ninth aspect, an embodiment of this specification further provides a chip, which includes: a memory for storing a computer program; a processor for reading and executing the computer program stored in the memory. After the processor calls and runs the computer program from the memory, an electronic device equipped with this chip system is caused to execute the method in the above first aspect or any possible implementation manner in the first aspect, or the method in the above second aspect or any possible implementation manner in the second aspect.

[0042] Compared with the prior art, the beneficial effects that can be achieved by at least one of the above technical solutions adopted in the embodiments of this specification at least include:

[0043] In this application, at least two downlink signals are designed on the satellite or network side, and the transmission frequencies of the at least two downlink signals are different. The UE receives the at least two downlink signals and determines an estimated value of the Doppler frequency offset and an estimated value of the local oscillator frequency error. When the UE performs uplink transmission, pre-compensation is performed respectively for the local oscillator frequency error and the Doppler frequency offset, which can solve the problem in the prior art that only an overall frequency offset can be estimated by receiving downlink signals, and an overall frequency offset pre-compensation is performed on the uplink signal, and there is a two-fold local oscillator frequency error in the uplink received signal. This application can achieve uplink frequency synchronization when the UE does not have GNSS capabilities, or in some scenarios such as indoor scenarios where the UE may not receive GNSS signals, or in order to save terminal power consumption, even if the UE has GNSS capabilities but may stop using the GNSS function, etc., improve the accuracy of frequency offset estimation, improve the performance of uplink frequency synchronization in satellite communication scenarios and improve the performance of initial random access, avoid a decrease in the uplink data transmission rate, and avoid an interruption of the uplink communication link. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of this application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0045] Figure 1 is a schematic diagram of Doppler frequency offset compensation in the prior art;

[0046] Figure 2 is a schematic diagram of a UE measuring frequency offset and pre-compensating an uplink signal in the prior art;

[0047] Figure 3 is a schematic diagram of a UE measuring frequency offset and pre-compensating an uplink signal provided by this application;

[0048] Figure 4 It is a flowchart of the uplink frequency synchronization method applied to a terminal device in this application;

[0049] Figure 5 It is a flowchart of the uplink frequency synchronization method applied to a network device in this application. Specific embodiments

[0050] The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0051] The following uses specific specific examples to illustrate the implementation manners of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. This application can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without making creative efforts belong to the scope of protection of this application.

[0052] It should be noted that the following describes various aspects of the embodiments within the scope of the appended claims. It should be obvious that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is illustrative only. Based on this application, those skilled in the art should understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects described herein can be used to implement the device and / or practice the method. In addition, this device and / or this method can be implemented using other structures and / or functions in addition to one or more of the aspects described herein.

[0053] It also needs to be noted that the drawings provided in the following embodiments only illustrate the basic concept of this application in a schematic manner. The drawings only show the components related to this application rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and ratio of each component in its actual implementation can be an arbitrary change, and the component layout type may also be more complex.

[0054] In addition, in the following description, specific details are provided for the purpose of facilitating a thorough understanding of the examples. However, those skilled in the art will understand that the examples can be practiced without these specific details.

[0055] The explanations of professional terms in the embodiments of this specification are as follows:

[0056] 1. Uplink: It refers to the direction in which data is transmitted from terminal devices (such as mobile phones, computers, etc.) to the network center (such as base stations, servers, etc.). For example, when users upload files, send emails, or upload audio and video data during video calls, etc., they all belong to uplink transmission.

[0057] 2. Downlink: It refers to the direction in which data is transmitted from the network center (such as base stations, servers, etc.) to terminal devices (such as mobile phones, computers, etc.). For example, in scenarios where users browse the web, watch online videos, download files, etc., the process of data transmission from the network to the user device is downlink transmission.

[0058] 3. Doppler frequency shift: Also known as Doppler frequency shift and Doppler frequency offset, the frequency difference between transmission and reception caused by the Doppler effect is called the Doppler frequency shift amount.

[0059] 4. Synchronization Signal and PBCH Block (SSB) is a synchronization signal block in the 5G NR (New Radio) system, which is jointly composed of Primary Synchronization Signals (PSS), Secondary Synchronization Signals (SSS), and Physical Broadcast Channel (PBCH). Its main function is to help the terminal device (UE) achieve downlink synchronization.

[0060] 5. Cell Defining SSB (CD-SSB) refers to the SSB associated with the Remaining Minimum System Information (RMSI), that is, when the SSB is associated with the RMSI, it is called CD-SSB. Non-Cell Defining SSB (NCD-SSB) is the opposite of Cell Defining SSB (CD-SSB). When the SSB is not associated with the RMSI, it is called NCD-SSB.

[0061] 6. Master Information Block (MIB) is the master information block in the 5G NR network. It contains the basic information and configuration parameters of the network and is the key information that the UE must obtain when initially accessing the network.

[0062] 7. SIB1 is System Information Block 1 in the 5G NR network. It carries the key information required for a UE (User Equipment) to access a cell and defines the scheduling of other system information. SIB1 is also known as the Remaining Minimum System Information (RMSI) and is the basis for a UE to access the network.

[0063] 8. MIB is the Master Information Block in the 5G NR network. It contains the basic information and configuration parameters of the network and is the key information that a UE must obtain when initially accessing the network.

[0064] 9. Frequency offset refers to the difference between the actual frequency and the expected frequency of a signal.

[0065] 10. Downlink synchronization signals are binary synchronization signal sequences periodically sent by a base station at specific positions. Terminal devices use these signals to synchronize with the base station in terms of frequency, phase, and frame synchronization, etc. Downlink synchronization is the starting point for a terminal device to establish communication with a base station. Only after synchronization is completed can the terminal demodulate the Master Information Block (MIB) and System Information Block (SIB) broadcast by the cell.

[0066] 11. Positive: In communication, positive usually refers to a positive frequency offset of a signal, that is, the actual frequency is higher than the expected frequency.

[0067] 12. Negative: Opposite to positive, negative refers to a negative frequency offset of a signal, that is, the actual frequency is lower than the expected frequency.

[0068] 13. Positive compensation: Usually, in a communication system, it refers to compensating for signal attenuation or distortion caused by factors such as loss and interference during signal transmission to enhance the transmission quality of the signal.

[0069] 14. Negative compensation: Opposite to positive compensation, negative compensation usually refers to adjusting the effects of certain enhancements or over-compensations during signal transmission to avoid other problems caused by over-compensation of the signal.

[0070] 15. MSG: In communication, MSG usually refers to a message or information, and its specific meaning depends on the context. For example, in the random access process of 5G, MSG1, MSG2, MSG3, and MSG4 refer to the random access preamble, random access response, scheduling request, and contention resolution message respectively.

[0071] 16. Frequency point: A frequency point refers to the specific frequency position of a signal in the frequency domain and is usually used to represent the center frequency or carrier frequency of the signal. For example, a wireless signal may be transmitted at a specific frequency, and this frequency is the frequency point of the signal.

[0072] 17. DL usually represents Downlink, which refers to the communication direction from the base station (or network-side device) to the terminal device (such as mobile phones, Internet of Things devices, etc.). For example, in a 5G network, when the base station sends data to a mobile phone, this process occurs in the downlink (DL).

[0073] 18. UL: UL usually represents Uplink, which refers to the direction of sending signals from the terminal device (such as mobile phones, Internet of Things devices, etc.) to the base station (or network-side device). For example, in a 5G network, when a user sends data from a mobile phone to the base station, this process occurs on the uplink (UL).

[0074] 19. NR-NTN is the abbreviation of "New Radio Non-Terrestrial Network", that is, "New Air Interface Non-Ground Network". It is a non-terrestrial network communication technology based on 5G NR (New Air Interface) technology, mainly used to provide communication services through wireless resources on platforms such as satellite platforms, unmanned aerial vehicle (UAV) platforms, or high altitude platform stations (HAPS) to achieve wide-area coverage and expand the transmission range of mobile signals. Among them, satellite platforms can include low earth orbit (LEO), medium earth orbit (MEO), and geosynchronous orbit (GEO).

[0075] 20. The preamble is the actual content sent by the terminal device in the physical random access channel (PRACH), which is used to synchronize and identify itself with the base station during initial access.

[0076] 21. Initial cell: It refers to the cell where the terminal device (such as a mobile phone) first accesses and camps when it is powered on or enters a new network coverage area.

[0077] Compared with traditional terrestrial mobile communications, satellite communications have the advantages of wide coverage and the ability to break geographical environment limitations, and can well extend and supplement terrestrial mobile communications. It is the key to achieving global seamless coverage. The 3rd Generation Partnership Project (3GPP) has included non-terrestrial networks (NTN) in the formulation of technical specification versions since Release 17, adapting to satellite communication scenarios by enhancing the 5G new radio (NR) protocol, and also laying a technical foundation for the research on satellite-terrestrial integration in 6G and subsequent networks.

[0078] In the standard evolution process of 3GPP NR-NTN up to now, there has been a basic working assumption: the User Equipment (UE) has the Global Navigation Satellite System (GNSS) function, and the UE can obtain its own location information based on GNSS measurements. Based on this assumption, the UE can estimate and pre-compensate for timing and frequency offsets to perform uplink transmission with sufficient accuracy.

[0079] In the satellite communication scenario, due to the high-speed movement of the satellite relative to the ground UE, a Doppler frequency offset far exceeding that of the ground communication system occurs. In order to extend the air interface technology of the existing ground network to the satellite communication scenario, in the prior art, both the UE and the network have the ability to pre-compensate for frequency offset (i.e., frequency offset pre-compensation). After the UE or the network side determines the Doppler frequency offset amount, frequency offset pre-compensation is performed on the uplink signal or the downlink signal to cancel the frequency deviation caused by the Doppler effect.

[0080] As Figure 1 shown, taking the current NR-NTN uplink frequency offset pre-compensation as an example, the Doppler frequency offset amount depends on the relative radial velocity between the UE and the satellite. The UE obtains the satellite ephemeris information by receiving the System Information Block (SIB) broadcast by the satellite. Currently, the ephemeris information provided in SIB19 includes the position and velocity information of the satellite. Assuming the moving speed of the satellite is v, in addition, the UE has a GNSS module that can obtain its own location information based on GNSS measurements. Therefore, the UE can determine the angle of the line-of-sight (LOS) propagation path between the UE and the satellite according to its own position and the position of the satellite, that is, the elevation angle θ of the UE. Then the relative radial velocity between the satellite and the UE is vcosθ, and the UE can calculate the Doppler frequency offset amount as where f c is the carrier frequency and c is the speed of light. Before sending the uplink signal, the calibrated uplink carrier frequency of the UE side is f c , and Doppler frequency offset pre-compensation is performed on the uplink transmission signal, that is, the frequency of the uplink signal actually sent by the UE is f UL,TX = f c - f d (1.2), that is, the pre-compensated frequency f UL,TX is obtained by subtracting the Doppler frequency offset amount from the calibrated frequency. Due to the relative movement between the UE and the satellite, the uplink signal is affected by the Doppler frequency offset, and the frequency of the received signal finally reaching the satellite is f UL,RX = f UL,TX + f d = fc (1.3). Therefore, the UE can determine the Doppler frequency offset based on the GNSS information and the ephemeris information of the satellite, and then pre-compensate the uplink signal to eliminate the influence of the Doppler frequency offset, achieve frequency synchronization, and ensure the uplink reception performance.

[0081] However, the working assumption that the UE has GNSS capabilities may not necessarily hold. For example, in order to save terminal costs, the UE may not have GNSS capabilities, or in some scenarios such as indoors, the UE may not be able to receive GNSS signals. Or, in order to save terminal power consumption, even if the UE has GNSS capabilities, it may stop using the GNSS function.

[0082] That is, based on the above basic working assumption, in the application scenario, there may be a situation where the UE does not have GNSS information, resulting in the inability to determine the Doppler frequency offset and pre-compensate the Doppler frequency offset, and causing problems in subsequent communication applications, such as a decrease in the uplink data transmission rate or even an uplink link interruption.

[0083] In summary, in the absence of GNSS information, it is impossible to determine the Doppler frequency offset and pre-compensate the Doppler frequency offset in the prior art. This problem needs to be considered in the evolving versions of future satellite communication standards.

[0084] Specifically, in one prior art, when the UE does not have GNSS information, the UE estimates the frequency offset by measuring the downlink reference signal. It can be found that in the measurement results, the estimated value of the frequency offset includes both the frequency offset caused by the Doppler shift and the carrier frequency offset caused by the local oscillator error.

[0085] As Figure 2 shown, usually the local oscillator accuracy on the satellite or network side is relatively high, but the local oscillator accuracy on the UE side is relatively low, resulting in a relatively large frequency offset impact. Figure 2 For simplicity of description, the frequency error of the local oscillator on the satellite or network side is ignored.

[0086] Assume that the carrier frequency offset caused by the UE local oscillator error is f UE,O , and the Doppler frequency offset caused by the relative movement between the satellite or network side and the UE is f D . Then, the UE side estimates the frequency offset by measuring the downlink reference signal as f shift = f UE,O + f D (2.1). Assume that the calibrated uplink carrier frequency is f UL . Due to the local oscillator error, the f UL that the UE thinks is actually the frequency of f UL - f UE,O(2.2) After frequency offset pre - compensation for the uplink signal, the actual uplink transmission frequency is f UL,Tx = f UL - f UE,O - f shift (2.3) where the pre - compensation amount is the frequency offset estimated value f shift of the UE. Finally, the uplink reception frequency at the satellite or network side is f UL,Rx = f UL,Tx + f D = f UL - f UE,O - f shift + f D = f UL - f UE,O - f UE,O - f D + f D = f UL - 2f UE,O (2.4) The frequency error between it and the calibrated uplink carrier frequency f UL is f err = 2f UE,O (2.5) (i.e., by passing and iterating each formula), this error will affect the uplink signal detection performance at the satellite or network side. Thus, it leads to the problem of twice the local oscillator frequency error, resulting in incorrect uplink frequency synchronization.

[0087] Generally speaking, in the case where the UE has no GNSS information, how to perform uplink frequency synchronization, including frequency offset pre - compensation of the uplink signal during the initial random access process, to improve the uplink transmission performance or the random access performance is a problem to be solved.

[0088] Based on this, the embodiments of this specification propose a new uplink frequency synchronization scheme. The inventors, by studying the problem of twice the local oscillator frequency error in the prior art, design at least two downlink signals at the satellite or network side with different transmission frequencies, so that the UE receives at least two downlink signals with different frequencies, and determines the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error. Before the UE performs uplink transmission, pre - compensation is performed respectively for the local oscillator frequency error and the Doppler frequency offset to determine the actual uplink transmission frequency, solve the problem of twice the local oscillator frequency error in the uplink received signal in the prior art, improve the accuracy of the frequency offset estimation, improve the uplink frequency synchronization performance in the satellite communication scenario, and improve the initial random access performance.

[0089] The following describes the technical solutions provided by the embodiments of the present application in conjunction with the accompanying drawings.

[0090] As Figure 3 and Figure 4As shown in the figure, an embodiment of this specification provides an uplink frequency synchronization method, which is applied to a terminal device and includes S401 - S404. Step S401: Receive at least two downlink signals, where the transmission frequencies of the at least two downlink signals are different. Step S402: Determine an estimated value of the Doppler frequency offset and an estimated value of the local oscillator frequency error based on the at least two downlink signals. Step S403: Determine the uplink transmission frequency according to the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error. Step S404: Transmit an uplink signal at the uplink transmission frequency.

[0091] Specifically, during the initial cell search process of the UE, or before initial access, or before transmitting an uplink signal, based on at least two downlink signals sent by a network device, the UE determines the frequency offset and the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error in the frequency offset to achieve uplink frequency synchronization and ensure uplink reception performance.

[0092] In step S401, at least two downlink signals are received, and the transmission frequencies of the at least two downlink signals are different. So that the UE can estimate the Doppler frequency offset and the local oscillator frequency error respectively based on the downlink signals.

[0093] Specifically, the inventors studied that the Doppler frequency offset is caused by the relative motion between the UE and the network device or satellite, and the local oscillator error is caused by insufficient accuracy of the UE's own oscillator or mismatch between the oscillators of the UE and the network device or satellite. By receiving at least two downlink signals sent by the network device, the UE estimates the frequency offset. Since the transmission frequencies of different downlink signals are different, the UE can separate the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error in the frequency offset.

[0094] In step S402, based on at least two downlink signals, the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error are determined, thereby improving the accuracy of the frequency offset estimation.

[0095] For example, if at least two downlink signals are received, the frequency points of the two downlink reference signals are f c,1 and f c,2 , and the estimated frequency offsets for the two downlink reference signals are f shift,1 and f shift,2 , where and v is the relative radial velocity between the network device or satellite and the UE, c is the speed of light, f UE,O is the frequency offset caused by the local oscillator error, f c,1 and f c,2 are known or the UE can measure and determine, then the UE can calculate v and f UE,O, so as to determine the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error, where, for the frequency point f c,1 The estimated value of the Doppler frequency offset is For the frequency point f c,2 The estimated value of the Doppler frequency offset is Furthermore, assuming that the carrier frequency of the uplink signal is represented as f UL , then for the frequency point f UL The estimated value of the Doppler frequency offset is

[0096] Among them, formulas 3.21 and 3.22 are obtained in the following way. The downlink signal sent by the satellite or network side is represented as x(n). Due to the relative motion between the satellite or base station and the UE, and the influence of the local oscillator frequency mismatch, the frequency of the downlink signal received by the UE side is frequency-shifted, and the received signal is represented as Among them, h(n) is the channel response without considering the Doppler effect, v is the relative radial velocity between the satellite or base station and the UE, is the influence of the Doppler frequency offset, f UE,O is the frequency offset caused by the local oscillator error, T s is the sampling time interval, and w(n) is the noise. The UE performs autocorrelation processing on the received signal r(n), or performs correlation processing on the received signal r(n) and the downlink signal x(n), and the overall frequency offset can be estimated, that is, formulas 3.21 and 3.22 are obtained through 3.2.

[0097] In step S403, the uplink transmission frequency is determined according to the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error.

[0098] Combined with the above embodiments, after appropriate compensation according to the separated estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error, the finally determined uplink actually received signal frequency is the uplink transmission frequency.

[0099] For example, the uplink transmission frequency adopts formula 3.3:

[0100] f UL,Tx = f UL + the corresponding compensation value of the estimated value of the Doppler frequency offset

[0101] + the corresponding compensation value of the estimated value of the local oscillator frequency error, where, f UL is the calibrated uplink carrier frequency, that is, the theoretical reference frequency. f UL,Tx is the uplink signal frequency actually sent by the UE, which is the frequency after frequency offset pre-compensation and is used to ensure the frequency synchronization of the uplink signal.

[0102] In step S404, an uplink signal is transmitted on the uplink transmission frequency.

[0103] Combined with the above embodiments, the uplink signal may include MSG1 during the random access process of the UE, etc. For example, the UE selects a preamble sequence according to the uplink transmission frequency during the random access process.

[0104] In some embodiments, the at least two downlink signals include a downlink synchronization signal and / or a downlink reference signal.

[0105] Specifically, the downlink synchronization signal may be an SSB, and the downlink reference signal may be a channel state information reference signal (CSI-RS), a phase tracking reference signal (PTRS), a demodulation reference signal (DMRS), etc.

[0106] In some embodiments, determining the Doppler frequency offset estimate and the local oscillator frequency error estimate according to the at least two downlink signals includes: determining the transmission frequencies of the at least two downlink signals; determining the Doppler frequency offset estimate and the local oscillator frequency error estimate according to the at least two downlink signals and the transmission frequencies of the at least two downlink signals.

[0107] Specifically, the transmission frequencies of the downlink signals are predefined, and the UE determines the transmission frequencies of the at least two downlink signals in a predefined manner.

[0108] Alternatively, the transmission frequencies of downlink signals such as CSI-RS or PTRS or DMRS are configured through configuration information, and the UE obtains the transmission frequencies of the downlink signals by receiving the configuration information.

[0109] Alternatively, the transmission frequency of a downlink signal such as an SSB is sent to the UE through SIB1 or MIB, that is, the UE obtains the transmission frequency of a downlink signal such as an SSB through SIB1 or MIB.

[0110] Alternatively, the UE estimates the frequency point position. For example, in the existing standard, the UE can determine the transmission frequency in the SSB during the initial cell search of the SSB, so as to determine the transmission frequencies of the at least two downlink signals.

[0111] Furthermore, according to the at least two downlink signals and the transmission frequencies of the at least two downlink signals, the Doppler frequency offset estimate and the local oscillator frequency error estimate are determined.

[0112] For example, the UE receives two downlink reference signals, and determines that the frequency points (i.e., transmission frequencies) of the two downlink reference signals are f c,1 and f c,2 , and the frequency offsets estimated for the two downlink reference signals are respectively and fc,1 and f c,2 are known, the UE will use the known c and f shift,1 , f shift,2 , f c,1 and f c,2 Substitute into Formulas 3.21 and 3.22, and determine v and f by solving Formulas 3.21 and 3.22 UE,O , thereby determining the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error. Among them, for the frequency point f c,1 The estimated value of the Doppler frequency offset is For the frequency point f c,2 The estimated value of the Doppler frequency offset is Furthermore, assume that the carrier frequency of the uplink signal is represented as f UL , then for the frequency point f UL The estimated value of the Doppler frequency offset is

[0113] In some embodiments, the transmission frequencies and frequency intervals of the at least two downlink signals are predefined.

[0114] Combined with the above embodiments, in the embodiments of the present specification, the satellite or network device transmits at least two downlink signals, and the predefined frequency interval provides a clear reference for the UE, enabling it to quickly locate and decode the downlink signals without GNSS information. By means of standard protocol regulations, system broadcast information notification, or configuration information indication, the UE can accurately determine the transmission frequencies of the at least two downlink signals and their intervals, thereby realizing the estimation of the frequency offset and uplink frequency synchronization. In order to finally realize the estimation of the Doppler frequency offset and the estimation of the local oscillator frequency error according to the transmission frequencies of the at least two downlink signals.

[0115] In some embodiments, receive the transmission frequency indication information of the at least two downlink signals, where the transmission frequency indication information of the at least two downlink signals includes the frequency interval indication information of the transmission frequencies of the at least two downlink signals, or the transmission frequency indication information of the at least two downlink signals includes the frequency domain resource configuration information of at least one of the at least two downlink signals; determine the transmission frequencies of the at least two downlink signals according to the transmission frequency indication information of the at least two downlink signals.

[0116] Combined with the above embodiments, the UE receives the transmission frequency indication information of at least two downlink signals, or receives the frequency-domain resource configuration information of at least one of the at least two downlink signals. The frequency-domain interval indication information enables the UE to calculate the transmission frequencies of other downlink signals through a known frequency interval and the frequency of one of the downlink signals. The frequency-domain resource configuration information enables the UE to directly obtain the absolute frequency position of a certain downlink signal, or deduce the frequencies of other signals in combination with the frequency interval. Regarding the definition of the position and related parameters of the SSB in the frequency domain, it directly indicates the center frequency point or frequency band range of the downlink signal, so that the UE can accurately find the position of the SSB in the frequency domain.

[0117] In some embodiments, the at least two downlink signals include at least one CD-SSB and at least one NCD-SSB, and the transmission frequency indication information of the at least two downlink signals includes the frequency interval indication information of the transmission frequencies of the NCD-SSB and the CD-SSB, or the transmission frequency indication information of the at least two downlink signals includes the frequency-domain resource configuration information of the NCD-SSB, and the transmission frequency indication information of the at least two downlink signals is included in the SIB1 / MIB corresponding to the CD-SSB.

[0118] Combined with the above embodiments, at least one of the at least two SSBs located at different frequency-domain positions among the at least two downlink signals is a Cell Defining SSB (CD-SSB) defined for the cell, and at least one is a Non-Cell Defining SSB (NCD-SSB).

[0119] The transmission frequency indication information of the at least two downlink signals includes the frequency interval indication information of the transmission frequencies of the NCD-SSB and the CD-SSB.

[0120] Alternatively, the transmission frequency indication information of the at least two downlink signals includes the frequency-domain resource configuration information of the NCD-SSB, indicating the frequency-domain interval between the NCD-SSB and the CD-SSB; wherein the transmission frequency indication information can be indicated by the SIB1 corresponding to the CD-SSB, or indicated by the Master Information Block (MIB) of the CD-SSB.

[0121] In some embodiments, at least the two downlink signals include at least two CD-SSBs.

[0122] Combined with the above embodiments, in the embodiments of this specification, the UE performs initial cell search, receives multiple SSBs, at least two of the multiple SSBs are located at different frequency points, and at least two downlink signals include at least two CD-SSBs. The transmission frequency indication information of at least two downlink signals is included in SIB1 or MIB.

[0123] In some embodiments, the determining the uplink transmission frequency according to the estimated Doppler frequency offset and the estimated local oscillator frequency error includes: determining a Doppler frequency offset compensation value according to the estimated Doppler frequency offset, where the Doppler frequency offset compensation value is the negative of the estimated Doppler frequency offset; determining a local oscillator error compensation value according to the estimated local oscillator frequency error, and the local oscillator frequency error compensation value is the positive of the estimated local oscillator frequency error; determining the uplink transmission frequency according to the Doppler frequency offset compensation value and the local oscillator frequency error compensation value.

[0124] Combined with the above embodiments, the estimated Doppler frequency offset and the estimated local oscillator frequency error are obtained by calculating according to Formulas 3.21 and 3.22.

[0125] The Doppler frequency offset is caused by the relative movement between the satellite and the UE. Through the estimation of the downlink signal, the received frequency of the downlink signal is the downlink transmission frequency superimposed with the Doppler frequency shift. Since the uplink signal also experiences the Doppler frequency shift, in order to make the received frequency of the uplink signal at the receiving end, i.e., the network device or the satellite side, consistent with the calibrated frequency, the UE needs to adjust the frequency of the uplink signal in the opposite direction of the Doppler estimation value. Therefore, the Doppler frequency offset compensation value is determined, and the Doppler frequency offset compensation value is the negative of the estimated Doppler frequency offset.

[0126] Assume that due to the local oscillator error f UE,O the frequency offset considered by the UE is larger than the actual frequency offset. Then, due to the local oscillator error, the f UL considered by the UE is actually the frequency f UL -f UE,O . To offset this offset, the UE needs to adjust the frequency of the uplink signal in the positive direction of the local oscillator error, that is, to determine the local oscillator frequency error compensation value, and the local oscillator frequency error compensation value is the positive of the estimated local oscillator frequency error.

[0127] Furthermore, according to the Doppler frequency offset compensation and the local oscillator frequency error compensation value, the uplink transmission frequency is determined. As shown in Formula 3.4: f UL , TX =f UL - estimated Doppler frequency offset + estimated local oscillator frequency error, f ULis the calibrated uplink transmission frequency considered by the UE under the influence of local oscillator error, f UL,TX is the actual uplink transmission frequency.

[0128] Combined with the above embodiments, an uplink frequency synchronization method according to an embodiment of this specification is applied to a network device, such as Figure 5 as shown, including step S501-step S502. Among them, step S501: Transmit at least two downlink signals, and the transmission frequencies of the at least two downlink signals are different, for the terminal device to determine the Doppler frequency offset estimation value and the local oscillator frequency error estimation value according to the at least two downlink signals. Step S502: Receive the uplink signal, and the transmission frequency of the uplink signal is determined by the terminal device according to the Doppler frequency offset estimation value and the local oscillator frequency error estimation value.

[0129] In step S501, the network device can broadcast the downlink signal to all UEs within the coverage area, or directly send the downlink signal to the UEs that need to be synchronized. In step S502, when receiving the uplink signal, the uplink signal is the signal after the UE performs frequency offset pre-compensation. The uplink signal may include MSG1 during the random access process of the UE, such as the UE selects a Preamble sequence according to the uplink transmission frequency during the random access process; the uplink signal may also include uplink physical signals or uplink physical channels.

[0130] Among them, the specific execution principle and implementation manner applied to the terminal device are similar to Figure 4 the example, and will not be elaborated here.

[0131] In some embodiments, the at least two downlink signals include a downlink synchronization signal and / or a downlink reference signal.

[0132] Specifically, a network device such as a satellite or a base station generates a downlink synchronization signal such as an SSB, and can send the SSB in a broadcast manner.

[0133] Or generate a downlink reference signal, and the downlink reference signal may be a channel state information reference signal (CSI-RS), a phase tracking reference signal (PTRS), a demodulation reference signal (DMRS), etc.

[0134] In some embodiments, the at least two downlink signals are used for the terminal device to determine the Doppler frequency offset estimation value and the local oscillator frequency error estimation value, including: the terminal device determines the transmission frequencies of the at least two downlink signals; the terminal device determines the Doppler frequency offset estimation value and the local oscillator frequency error estimation value according to the at least two downlink signals and the transmission frequencies of the at least two downlink signals.

[0135] Specifically, the network device pre - defines the transmission frequencies of downlink signals, and the UE determines the transmission frequencies of at least two downlink signals through a predefined method. Alternatively, the network device configures the transmission frequencies of downlink signals such as CSI - RS or PTRS or DMRS through configuration information, and the UE obtains the transmission frequencies of downlink signals by receiving the configuration information. Alternatively, the network device sends the transmission frequencies of downlink signals such as SSB to the UE through SIB1 or MIB, that is, the UE obtains the transmission frequencies of downlink signals such as SSB through SIB1 or MIB. Alternatively, the UE estimates the frequency point position. For example, in the existing standard, the UE can determine the transmission frequency in the SSB during the initial cell search, so as to determine the transmission frequencies of at least two downlink signals. Combining the above - mentioned embodiments, the terminal device, such as by solving formulas 3.21 and 3.22, determines the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error, that is, based on at least two downlink signals and the transmission frequencies of at least two downlink signals, determines the estimated value of the Doppler frequency offset and the estimated value of the local oscillator frequency error.

[0136] In some embodiments, the frequency interval of the transmission frequencies of the at least two downlink signals is pre - defined.

[0137] Combining the above - mentioned embodiments, in the embodiments of this specification, the satellite or the network side pre - defines the information related to at least two downlink signals. The pre - defined frequency interval provides a clear reference for the UE, enabling it to quickly locate and decode downlink signals without GNSS information. The satellite or the network side pre - defines the frequency interval of the transmission frequencies of the at least two downlink signals in the manner specified by the standard protocol. So that the UE can accurately determine the transmission frequencies of at least two downlink signals and their intervals, thereby realizing the estimation of the frequency offset and the uplink frequency synchronization.

[0138] In some embodiments, the transmission frequency indication information of the at least two downlink signals is sent, where the transmission frequency indication information of the at least two downlink signals includes the frequency interval indication information of the transmission frequencies of the at least two downlink signals, or the transmission frequency indication information of the at least two downlink signals includes the frequency domain resource configuration information of at least one downlink signal among the at least two downlink signals; so that the terminal device determines the transmission frequencies of the at least two downlink signals according to the transmission frequency indication information of the at least two downlink signals.

[0139] Combined with the above embodiments, the network device can define and set the center frequency point interval of at least two downlink signals (such as two SSBs) as a fixed value, which can be standardized, that is, a way to form the transmission frequency indication information of at least two downlink signals. Another network device allocates frequency domain resource configuration information for each downlink signal (such as a reference signal) and sends this frequency domain resource configuration information to the UE. The network device broadcasts or configures the transmission frequency indication information of at least two downlink signals to the UE through, such as SIB1 or MIB or configuration information, or directly defines it in the protocol, so that the UE can obtain the transmission frequency indication information of at least two downlink signals.

[0140] In some embodiments, at least two downlink signals include at least one CD-SSB and at least one NCD-SSB. The transmission frequency indication information of the at least two downlink signals includes the frequency interval indication information of the transmission frequencies of the NCD-SSB and the CD-SSB. Alternatively, the transmission frequency indication information of the at least two downlink signals includes the frequency domain resource configuration information of the NCD-SSB, and the transmission frequency indication information of the at least two downlink signals is included in the SIB1 / MIB corresponding to the CD-SSB.

[0141] Specifically, the satellite or the network side sends at least two SSBs with different frequency points. At least one of the at least two SSBs is a CD-SSB and at least one is an NCD-SSB. The transmission frequency indication information of the at least two downlink signals includes the frequency interval indication information of the transmission frequencies of the NCD-SSB and the CD-SSB. Alternatively, the transmission frequency indication information of the at least two downlink signals includes the frequency domain resource configuration information of the NCD-SSB, and the transmission frequency indication information of the at least two downlink signals is included in the SIB1 / MIB corresponding to the CD-SSB.

[0142] In some embodiments, the at least two downlink signals include at least two CD-SSBs.

[0143] Specifically, the satellite or the network side sends at least two SSBs with different frequency points. For example, if at least two SSBs are both CD-SSBs, the satellite or the network side defines the center frequency point position of each CD-SSB or defines the frequency interval between CD-SSBs, and can also broadcast it to the UE through SIB1 or MIB, so that the UE can perform initial cell search and estimate the frequency offset, improving the estimation accuracy.

[0144] In some embodiments, the uplink transmission frequency of the uplink signal is determined by the terminal device according to the estimated Doppler frequency offset and the estimated local oscillator frequency error, including: the terminal device determines a Doppler frequency offset compensation value according to the estimated Doppler frequency offset, and the Doppler frequency offset compensation value is the negative of the estimated Doppler frequency offset; the terminal device determines a local oscillator frequency error compensation value according to the estimated local oscillator frequency error, and the local oscillator frequency error compensation value is the positive of the estimated local oscillator frequency error; the terminal device determines the uplink transmission frequency according to the Doppler frequency offset compensation value and the local oscillator frequency error compensation value. Wherein, the uplink signal is the signal after the UE performs frequency offset pre-compensation, and the uplink signal may also include uplink physical signals or uplink physical channels. Combining the above embodiments, the terminal device determines the uplink transmission frequency through Equation 3.4.

[0145] Combining the above embodiments, an embodiment of the present specification provides an uplink frequency synchronization device, which is applied to a terminal device and includes:

[0146] A first receiving module, configured to receive at least two downlink signals with different transmission frequencies;

[0147] A first determining module, configured to determine an estimated Doppler frequency offset and an estimated local oscillator frequency error according to the at least two downlink signals;

[0148] A second determining module, configured to determine an uplink transmission frequency according to the estimated Doppler frequency offset and the estimated local oscillator frequency error;

[0149] A first transmitting module, configured to transmit an uplink signal at the uplink transmission frequency.

[0150] Combining the above embodiments, an embodiment of the present specification provides an uplink frequency synchronization device, which is applied to a network device and includes:

[0151] A second transmitting module, configured to transmit at least two downlink signals with different transmission frequencies, and the at least two downlink signals are used for the terminal device to determine an estimated Doppler frequency offset and an estimated local oscillator frequency error;

[0152] A second receiving module, configured to receive an uplink signal from the terminal device, where the uplink transmission frequency of the uplink signal is determined by the terminal device according to the estimated Doppler frequency offset and the estimated local oscillator frequency error.

[0153] In combination with the above embodiments, the embodiments of the present specification further provide a communication device, including any of the methods described in the technical solutions applied to the terminal device above, or for executing any of the methods described in the technical solutions applied to the network device above.

[0154] The embodiments of the present specification further provide a communication device, the device includes at least one processor, and the at least one processor is coupled to at least one memory: the at least one processor is configured to execute computer programs or instructions in the at least one memory, so that the communication device executes any of the methods described in the technical solutions applied to the terminal device, or executes any of the methods described in the technical solutions applied to the network device.

[0155] The embodiments of the present specification further provide a communication system, the communication system includes a terminal device and a network device; the terminal device is configured to execute any of the methods described in the technical solutions applied to the terminal device; the network device is configured to execute any of the methods described in the technical solutions applied to the network device.

[0156] The embodiments of the present specification further provide a computer-readable storage medium, in which computer programs or instructions are stored, and when a computer reads and executes the computer programs or instructions, the computer is caused to execute any of the methods described in the technical solutions applied to the terminal device, or execute any of the methods described in the technical solutions applied to the network device.

[0157] The embodiments of the present specification further provide a chip, including: a memory for storing computer programs; a processor for reading and executing the computer programs stored in the memory, and after the processor calls and runs the computer programs from the memory, causing the electronic device installed with the chip system to execute any of the methods described in the technical solutions of the terminal device, or execute any of the methods described in the technical solutions of the network device.

[0158] The embodiments of the present specification further provide a computer program product, the computer program product includes a computer program, and when the computer program runs on a computer, causing the computer to execute any of the methods described in the technical solutions applied to the terminal device, or execute any of the methods described in the technical solutions of the network device.

[0159] For the same or similar parts among the embodiments in the present specification, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the product embodiments described later, since they correspond to the methods, the description is relatively simple, and the relevant parts can refer to the partial description of the system embodiments.

[0160] As described above, it is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. An uplink frequency synchronization method, characterized in that: Applied to terminal equipment, including: receiving at least two downlink signals, wherein the at least two downlink signals have different transmission frequencies; Determine a Doppler frequency offset estimate and a local oscillator frequency error estimate based on the at least two downlink signals; Determining an uplink transmission frequency according to the Doppler frequency offset estimate and the local oscillator frequency error estimate; An uplink signal is sent on the uplink sending frequency.

2. The method according to claim 1, characterized in that The at least two downlink signals include a downlink synchronization signal and / or a downlink reference signal.

3. The method according to claim 1 or 2, characterized in that: The step of determining a Doppler frequency offset estimate and a local oscillator frequency error estimate according to the at least two downlink signals comprises: Determining a sending frequency of the at least two downlink signals; A Doppler frequency offset estimate and a local oscillator frequency error estimate are determined according to the at least two downlink signals and the transmission frequencies of the at least two downlink signals.

4. The method according to claim 3, characterized in that: The frequency interval between the transmission frequencies of the at least two downlink signals is predefined.

5. The method according to claim 3, characterized in that: Also includes: receiving transmission frequency indication information of the at least two downlink signals, where the transmission frequency indication information of the at least two downlink signals includes frequency interval indication information of the transmission frequencies of the at least two downlink signals, or the transmission frequency indication information of the at least two downlink signals includes frequency domain resource configuration information of at least one downlink signal of the at least two downlink signals; The sending frequencies of the at least two downlink signals are determined according to the sending frequency indication information of the at least two downlink signals.

6. The method according to claim 5, characterized in that: The at least two downlink signals include at least one CD-SSB and at least one NCD-SSB, and the sending frequency indication information of the at least two downlink signals includes frequency interval indication information of the sending frequencies of the NCD-SSB and the CD-SSB, or, the sending frequency indication information of the at least two downlink signals includes frequency domain resource configuration information of the NCD-SSB, and the sending frequency indication information of the at least two downlink signals is included in the SIB1 / MIB corresponding to the CD-SSB.

7. The method according to any one of claims 1 to 5, characterized in that: The at least two downlink signals include at least two CD-SSBs.

8. The method according to any one of claims 1 to 7, characterized in that: The determining the uplink transmission frequency according to the Doppler frequency offset estimate and the local oscillator frequency error estimate includes: Determining a Doppler frequency offset compensation value according to the Doppler frequency offset estimate, wherein the Doppler frequency offset compensation value is a negative Doppler frequency offset estimate; Determining a local oscillator frequency error compensation value according to a local oscillator frequency error estimate, wherein the local oscillator frequency error compensation value is a positive local oscillator frequency error estimate; An uplink transmission frequency is determined according to the Doppler frequency offset compensation value and the local oscillator frequency error compensation value.

9. An uplink frequency synchronization method, characterized in that: Applied to network equipment, including: Sending at least two downlink signals, wherein the at least two downlink signals have different sending frequencies, and the at least two downlink signals are used by the terminal device to determine a Doppler frequency offset estimate and a local oscillator frequency error estimate; An uplink signal is received from the terminal device, wherein the uplink transmission frequency of the uplink signal is determined by the terminal device according to the Doppler frequency offset estimate and the local oscillator frequency error estimate.

10. The method according to claim 9, characterized in that: The at least two downlink signals include a downlink synchronization signal and / or a downlink reference signal.

11. The method according to claim 9 or 10, characterized in that: The at least two downlink signals are used by the terminal device to determine a Doppler frequency offset estimate and a local oscillator frequency error estimate, including: The terminal device determines the sending frequency of the at least two downlink signals; The terminal device determines a Doppler frequency offset estimate and a local oscillator frequency error estimate based on the at least two downlink signals and the transmission frequencies of the at least two downlink signals.

12. The method according to claim 11, characterized in that Also includes: The frequency interval between the transmission frequencies of the at least two downlink signals is predefined.

13. The method according to claim 11, characterized in that Also includes: Sending frequency indication information of the at least two downlink signals, wherein the sending frequency indication information of the at least two downlink signals includes frequency interval indication information of the sending frequencies of the at least two downlink signals, or the sending frequency indication information of the at least two downlink signals includes frequency domain resource configuration information of at least one downlink signal of the at least two downlink signals; the sending frequency indication information of the at least two downlink signals is used by the terminal device to determine the sending frequencies of the at least two downlink signals.

14. The method according to claim 13, characterized in that The at least two downlink signals include at least one CD-SSB and at least one NCD-SSB, and the sending frequency indication information of the at least two downlink signals includes frequency interval indication information of the sending frequencies of the NCD-SSB and the CD-SSB, or, the sending frequency indication information of the at least two downlink signals includes frequency domain resource configuration information of the NCD-SSB, and the sending frequency indication information of the at least two downlink signals is included in the SIB1 / MIB corresponding to the CD-SSB.

15. The method according to any one of claims 9 to 13, characterized in that: The at least two downlink signals include at least two CD-SSBs.

16. The method according to any one of claims 9 to 15, characterized in that: The uplink transmission frequency of the uplink signal is determined by the terminal device according to the Doppler frequency offset estimate and the local oscillator frequency error estimate, including: The terminal device determines a Doppler frequency offset compensation value according to the Doppler frequency offset estimation value, wherein the Doppler frequency offset compensation value is a negative Doppler frequency offset estimation value; The terminal device determines a local oscillator frequency error compensation value according to the local oscillator frequency error estimate value, wherein the local oscillator frequency error compensation value is a positive local oscillator frequency error estimate value; The terminal device determines the uplink transmission frequency according to the Doppler frequency offset compensation value and the local oscillator frequency error compensation value.

17. An uplink frequency synchronization device, characterized in that: Applied to terminal equipment, including: A first receiving module, configured to receive at least two downlink signals, wherein the at least two downlink signals have different transmission frequencies; A first determination module, configured to determine a Doppler frequency offset estimate and a local oscillator frequency error estimate according to the at least two downlink signals; A second determination module, configured to determine an uplink transmission frequency according to the Doppler frequency offset estimate and the local oscillator frequency error estimate; The first sending module is used to send an uplink signal on the uplink sending frequency.

18. An uplink frequency synchronization device, characterized in that: Applied to network equipment, including: A second sending module, used for sending at least two downlink signals, the at least two downlink signals have different sending frequencies, and the at least two downlink signals are used by the terminal device to determine a Doppler frequency offset estimate and a local oscillator frequency error estimate; The second receiving module is used to receive an uplink signal from the terminal device, and the uplink sending frequency of the uplink signal is determined by the terminal device according to the Doppler frequency offset estimate and the local oscillator frequency error estimate.

19. A communication device, characterized in that: The method comprises a method for executing any one of claims 1 to 8, or a method for executing any one of claims 9 to 16.

20. A communication device, characterized in that: The device includes at least one processor, which is coupled to at least one memory: the at least one processor is used to execute a computer program or instruction in the at least one memory so that the communication device performs the method as described in any one of claims 1 to 8, or performs the method as described in any one of claims 9 to 16.

21. A communication system, characterized in that: It comprises a terminal device and a network device; the terminal device is used to execute the method as claimed in any one of claims 1 to 8; the network device is used to execute the method as claimed in any one of claims 9 to 16.

22. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program or instructions. When a computer reads and executes the computer program or instructions, the computer executes the method as claimed in any one of claims 1 to 8, or executes the method as claimed in any one of claims 9 to 16.

23. A chip, characterized in that: include: Memory for storing computer programs; A processor, used to read and execute the computer program stored in the memory. When the processor calls and runs the computer program from the memory, the electronic device equipped with the chip system executes the method as described in any one of claims 1 to 8, or executes the method as described in any one of claims 9 to 16.

24. A computer program product, characterized in that The computer program product comprises a computer program, and when the computer program is run on a computer, the computer is caused to execute the method according to any one of claims 1 to 8 or the method according to any one of claims 9 to 16.

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