Communication methods, apparatuses, and systems

Abstract

The application provides a communication method, device and system, and relates to the technical field of communication. In the method, a terminal can determine a Doppler frequency offset according to a frequency offset estimation value determined in a synchronization process and a frequency point indicated by a base station. In this way, the terminal can obtain a more accurate Doppler frequency offset without using GNSS, and the terminal uses the more accurate Doppler frequency offset to compensate for a transmission frequency point of an uplink signal, which helps to improve the accuracy of frequency offset compensation and improve the reliability of communication.

Description

Technical Field

[0001] This application relates to the field of communications, and more particularly to a communication method, apparatus, and system. Background Technology

[0002] The Doppler effect refers to the phenomenon where the frequency of a wave perceived by an observer changes when there is relative motion between the wave source and the observer. When the wave source moves closer to the observer, the frequency of the wave received by the observer increases. When the wave source moves away from the observer, the frequency of the wave received by the observer decreases. The Doppler effect can also exist in mobile communication systems. Taking the downlink as an example, the base station can be understood as the wave source, and the terminal as the observer. When there is relative motion between the base station and the terminal, there is a shift between the frequency of the signal received by the terminal and the transmission frequency of the signal transmitted by the base station; this shift is called the Doppler frequency offset.

[0003] In some scenarios, Doppler frequency offset may affect the demodulated signal of network equipment, thus affecting the reliability of communication. Summary of the Invention

[0004] This application provides a communication method, apparatus, and system to improve the accuracy of frequency offset compensation and enhance the reliability of communication.

[0005] Firstly, a communication method is provided, which can be executed by a terminal or by a unit / module / component (such as a chip, chip system, logic circuit, or software) configurable in (or usable in) the terminal. The following explanation uses the execution of this method by a terminal as an example.

[0006] The method includes: a terminal detecting a synchronization signal at a first frequency point and obtaining a first frequency offset, the first frequency point being determined based on a synchronization grid, the first frequency offset being the frequency offset between the center frequency point of the detected synchronization signal and the first frequency point; the terminal receiving first information, the first information being used to indicate a second frequency point; the terminal determining a second frequency offset based on the second frequency point and the first frequency offset; and the terminal sending second information, the transmission frequency point of the second information being obtained after frequency offset compensation based on the second frequency offset.

[0007] According to the above scheme, the terminal can determine the Doppler frequency offset based on the frequency offset estimate determined during the synchronization process and the frequency point indicated by the network device. In this way, the terminal can obtain a more accurate Doppler frequency offset without using GNSS. The terminal uses this more accurate Doppler frequency offset to compensate for the uplink signal transmission frequency point, which helps to improve the accuracy of frequency offset compensation and improve the reliability of communication.

[0008] The specific second frequency point may include, but is not limited to, the following methods 1 and 2.

[0009] In Method 1, the second frequency point is the center frequency point of the synchronization signal sent by the network device (such as a base station), and the second frequency offset is the frequency offset between the detected center frequency point of the synchronization signal and the second frequency point.

[0010] The second frequency point can also be understood as the actual transmission frequency point of the network device sending the synchronization signal. In other words, the second frequency offset is the frequency offset between the center frequency point of the detected synchronization signal and the actual transmission frequency point of the network device sending the synchronization signal.

[0011] Optionally, the network device may indicate the second frequency point to the terminal via at least one of the following: the first information indicating the second frequency point, the global synchronization channel number (GSCN) corresponding to the second frequency point, or the absolute radio-frequency channel number (ARFCN). Specific indication methods can be found below. Figure 5 The relevant descriptions of the embodiments shown are not repeated here.

[0012] In conjunction with the first aspect, in some implementations of the first aspect, the terminal determines the second frequency offset based on the second frequency point and the first frequency offset, including: the terminal determines the second frequency offset based on the first frequency point, the second frequency point and the first frequency offset.

[0013] Optionally, the terminal can determine the center frequency of the detected synchronization signal by adding a first frequency point to a first frequency offset. The second frequency offset is then determined by the difference between the center frequency of the detected synchronization signal and a second frequency point. For example, the first frequency point f1, the second frequency point f2, the first frequency offset Δf1, and the second frequency offset Δf2 satisfy: Δf2 = f1 + Δf1 - f2.

[0014] According to the above scheme, the terminal can determine the actual Doppler frequency offset (or estimated Doppler frequency offset) between the terminal and the network device based on the frequency point of the synchronization signal indicated by the network device (second frequency point), the frequency offset estimate determined by the terminal during the synchronization process (first frequency offset), and the first frequency point determined based on the synchronization grid. This helps improve the accuracy of the Doppler frequency offset determined by the terminal. The terminal compensates the uplink signal transmission frequency point based on this more accurate Doppler frequency offset, which helps improve the reliability of communication.

[0015] Method 2: The second frequency point is the reference frequency point indicated by the network device (such as a base station).

[0016] Optionally, the reference frequency can be the frequency of point A.

[0017] Optionally, the terminal determines the second frequency offset based on the second frequency point and the first frequency offset, including: the terminal determines the second frequency offset based on the second frequency point, the first frequency offset, the third frequency offset, and the fourth frequency offset, wherein the third frequency offset is the frequency offset between the reference frequency point and the lowest subcarrier frequency of the common resource block where the lowest subcarrier frequency of the synchronization signal is located, and the fourth frequency offset is the frequency offset between the lowest subcarrier frequency of the synchronization signal and the lowest subcarrier frequency of the common resource block where the lowest subcarrier frequency of the synchronization signal is located.

[0018] Optionally, the terminal determines the second frequency offset based on the second frequency point, the first frequency offset, the third frequency offset, and the fourth frequency offset, which may include, but is not limited to, the following methods 2-1 and 2-2.

[0019] In method 2-1, the terminal determines the center frequency of the synchronization signal transmitted by the network device based on the second frequency point, the third frequency offset, the fourth frequency offset, and the bandwidth of the synchronization signal; the terminal determines the second frequency offset based on the first frequency point, the center frequency point of the synchronization signal transmitted by the network device, and the first frequency offset, wherein the second frequency offset is the frequency offset between the detected center frequency point of the synchronization signal and the center frequency point of the synchronization signal transmitted by the network device. For example, the first frequency point f1, the center frequency point f2 of the synchronization signal transmitted by the network device, the first frequency offset Δf1, and the second frequency offset Δf2 satisfy:

[0020] Δf2=f1+Δf1-f2.

[0021] According to the above scheme, the terminal can determine the center frequency of the synchronization signal based on the reference frequency indicated by the network device and the possible frequency offset between the reference frequency and the center frequency of the synchronization signal. Combining this with the first frequency offset and the first frequency, the terminal can determine (or estimate) the actual Doppler frequency offset (or Doppler frequency offset estimate) between the terminal and the network device, which helps improve the accuracy of the Doppler frequency offset determined by the terminal. The terminal compensates for the uplink signal transmission frequency based on this more accurate Doppler frequency offset, which helps improve the reliability of communication.

[0022] In method 2-2, the terminal determines the lowest subcarrier frequency of the detected synchronization signal based on the first frequency point, the first frequency offset, and the bandwidth of the synchronization signal; the terminal obtains the reference frequency point determined by the terminal based on the lowest subcarrier frequency of the detected synchronization signal, the third frequency offset, and the fourth frequency offset; the terminal determines the second frequency offset based on the second frequency point and the reference frequency point determined by the terminal, wherein the second frequency offset is the frequency offset between the reference frequency point determined by the terminal and the second frequency point.

[0023] For example, the first frequency point f1, the second frequency point f2, the first frequency offset Δf1, and the synchronization signal bandwidth B ssb The second frequency offset Δf2, the third frequency offset Δf3, and the fourth frequency offset Δf4 satisfy the following:

[0024] Δf2=f1+Δf1-0.5B ssb -Δf3-Δf4-f2.

[0025] According to the above scheme, the terminal can determine the center frequency of the synchronization signal detected by the terminal based on the first frequency point and the first frequency offset. Furthermore, it can obtain the reference frequency point determined by the terminal from possible frequency points between the center frequency point of the synchronization signal and the reference frequency point (such as the third frequency offset, the fourth frequency point, and half the bandwidth of the synchronization signal). Based on this terminal-determined reference frequency point and the reference frequency point indicated by the base station, the terminal can determine (or estimate) the actual Doppler frequency offset (or Doppler frequency offset estimate) between the terminal and the network equipment, which helps improve the accuracy of the Doppler frequency offset determined by the terminal. The terminal compensates for the transmission frequency point of the uplink signal based on this more accurate Doppler frequency offset, which helps improve the reliability of communication.

[0026] This application is not limited to this; network devices may also indicate other reference frequencies to base stations.

[0027] In one possible implementation, when the reference frequency is other than point A, the terminal can determine the center frequency of the synchronization signal sent by the network device based on the other reference frequency and the possible frequency offset between the other reference frequency and the center frequency of the synchronization signal, and determine the Doppler frequency offset based on the center frequency of the synchronization signal sent by the network device and the center frequency of the synchronization signal detected by the terminal.

[0028] In another possible implementation, when the reference frequency is other than point A, the terminal can determine the reference frequency based on the center frequency of the synchronization signal detected by the terminal and the possible frequency offset between the other reference frequency and the center frequency of the synchronization signal, and determine the Doppler frequency offset based on the reference frequency determined by the terminal and the reference frequency indicated by the network device.

[0029] In conjunction with the first aspect, in some implementations of the first aspect, the first information includes at least one of the following corresponding to the second frequency point: a global synchronization channel number; or an absolute radio frequency channel number.

[0030] According to the above scheme, the base station can indirectly indicate the second frequency point to the terminal by indicating the global synchronization channel number or the absolute radio frequency channel number, which helps to reduce the resource overhead of the first information.

[0031] Secondly, a communication method is provided, which can be executed by a network device (such as a base station) or by a unit / module / component (such as a chip, chip system, logic circuit, or software) configurable in (or usable in) a network device. The following explanation uses the execution of this method by a network device as an example.

[0032] The method includes: a network device sending a synchronization signal; the network device sending first information, the first information being used to indicate a second frequency point, wherein the synchronization signal and the second frequency point are used by the terminal to determine the frequency offset for frequency offset compensation of uplink information.

[0033] In conjunction with the second aspect, in some implementations of the second aspect, the second frequency point is the center frequency point of the synchronization signal; or, the second frequency point is the reference frequency point.

[0034] In conjunction with the second aspect, in some implementations of the second aspect, the first information includes at least one of the following corresponding to the second frequency point: a global synchronization channel number; or an absolute radio frequency channel number.

[0035] Thirdly, a communication device is provided. In one design, the device may include modules corresponding to the methods / operations / steps / actions described in the first aspect or any embodiment of the first aspect. These modules may be hardware circuits, software, or a combination of hardware circuits and software. In one design, the device includes: a processing unit configured to detect a synchronization signal at a first frequency point and obtain a first frequency offset, the first frequency point being determined based on a synchronization grid, and the first frequency offset being the frequency offset between the detected center frequency point of the synchronization signal and the first frequency point; and a transceiver unit configured to receive first information indicating a second frequency point. The processing unit is further configured to determine a second frequency offset based on the second frequency point and the first frequency offset. The transceiver unit is further configured to transmit second information, the transmission frequency of which is obtained after frequency offset compensation based on the second frequency offset.

[0036] Fourthly, a communication device is provided. In one design, the device may include modules corresponding to the methods / operations / steps / actions described in the second aspect or any of the embodiments of the second aspect. These modules may be hardware circuits, software, or a combination of hardware circuits and software. In one design, the device includes: a transceiver unit for transmitting a synchronization signal; the transceiver unit is further configured to transmit first information, the first information indicating a second frequency point, wherein the synchronization signal and the second frequency point are used by the terminal to determine the frequency offset for frequency offset compensation of the uplink information.

[0037] Fifthly, a communication device is provided, including a processor. The processor can implement the methods of the first to second aspects and any possible implementations thereof. Optionally, the communication device further includes a memory, and the processor is coupled to the memory and can be used to execute instructions in the memory to implement the methods of the first to second aspects and any possible implementations thereof. Optionally, the communication device further includes a communication interface, and the processor is coupled to the communication interface. In the embodiments of this application, the communication interface may be a transceiver, a pin, a circuit, a bus, a module, or other types of communication interface, and is not limited thereto.

[0038] In one implementation, the communication device is a communication equipment (such as a terminal or access network equipment). When the communication device is a communication equipment, the communication interface can be a transceiver, or an input / output interface.

[0039] In another implementation, the communication device is a chip configured within a communication device. When the communication device is a chip configured within a communication device, the communication interface can be an input / output interface.

[0040] Optionally, the transceiver can be a transceiver circuit. Optionally, the input / output interface can be an input / output circuit.

[0041] A sixth aspect provides a processor, comprising: an input circuit, an output circuit, and a processing circuit. The processing circuit is configured to receive signals through the input circuit and transmit signals through the output circuit, causing the processor to execute the methods described in the first to second aspects and any possible implementation thereof.

[0042] In specific implementation, the processor can be one or more chips, the input circuit can be input pins, the output circuit can be output pins, and the processing circuit can be transistors, gate circuits, flip-flops, and various logic circuits. The input signal received by the input circuit can be received and input by, for example, but not limited to, a receiver, and the signal output by the output circuit can be, for example, but not limited to, output to and transmitted by a transmitter. Furthermore, the input circuit and the output circuit can be the same circuit, which is used as both the input circuit and the output circuit at different times. This application does not limit the specific implementation of the processor and various circuits.

[0043] In a seventh aspect, a computer program product is provided, comprising: a computer program (also referred to as code or instructions) that, when run, causes a computer to perform the methods described in the first to second aspects and any possible implementation thereof.

[0044] Eighthly, a computer-readable storage medium is provided that stores a computer program (also referred to as code or instructions) that, when executed on a computer, causes the computer to perform the methods described in the first to second aspects and any possible implementation thereof.

[0045] A ninth aspect provides a chip system applied to an electronic device, the chip system including one or more processors, the one or more processors being configured to invoke computer instructions to cause the electronic device to perform the methods of the first to second aspects and any possible implementation thereof.

[0046] In a tenth aspect, a communication system is provided, comprising at least one network device and at least one terminal as described above.

[0047] It should be understood that the beneficial effects of the features corresponding to the first aspect in the second to tenth aspects can be referred to the relevant description of the first aspect above, and will not be repeated here. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the architecture of the communication system provided in the embodiments of this application;

[0049] Figure 2 This is a schematic diagram of the time-frequency structure of the SSB provided in the embodiments of this application;

[0050] Figure 3 This is a schematic diagram illustrating the Doppler frequency offset between the satellite base station and the terminal provided in this application embodiment;

[0051] Figure 4 This is a schematic diagram of the center frequency point of the SSB provided in the embodiments of this application;

[0052] Figure 5 This is a schematic flowchart of the communication method provided in the embodiments of this application;

[0053] Figure 6 This is a schematic diagram illustrating the relationship between the first frequency point, the second frequency point, the first frequency offset, and the second frequency offset, as provided in the embodiments of this application.

[0054] Figure 7 This is a schematic diagram illustrating the relationship between the first frequency point, the second frequency point, the first frequency offset, and the second frequency offset, as provided in the embodiments of this application.

[0055] Figure 8 This is a schematic diagram illustrating the relationship between the third type of first frequency point, second frequency point, first frequency offset, and second frequency offset provided in the embodiments of this application;

[0056] Figure 9This is a schematic diagram illustrating the relationship between the fourth type of first frequency point, second frequency point, first frequency offset, and second frequency offset provided in the embodiments of this application;

[0057] Figure 10 This is a schematic diagram illustrating the relationship between SSB and point A provided in an embodiment of this application;

[0058] Figure 11 This is a schematic block diagram of an example of a communication device provided in an embodiment of this application;

[0059] Figure 12 This is a schematic structural diagram of another example of the communication device provided in the embodiments of this application. Detailed Implementation

[0060] To facilitate understanding of the embodiments of this application, the following points are first explained:

[0061] In the embodiments of this application, "instruction" may include direct instruction, indirect instruction, explicit instruction, and implicit instruction. When describing a certain instruction information for indicating A, it can be understood that the instruction information carries A, directly indicates A, or indirectly indicates A.

[0062] In the embodiments of this application, " / " can indicate that the objects before and after are in an "or" relationship. For example, A / B can mean A or B. "And / or" can be used to describe three relationships between the associated objects. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. A and B can be singular or plural.

[0063] In the embodiments of this application, "at least one" refers to one or more, and "more than one" refers to two or more, such as three, four or more. Similar expressions (such as at least one, at least one, etc.) are used in the same way. "At least one of the following," "one or more of the following," or similar expressions refer to any combination of these items, which may include only a single item or a combination of multiple items. For example, at least one of a, b, or c can represent: a, or b, or c; a and b; or a and c; or b and c; or a, b, and c. Where a, b, and c can be single or multiple.

[0064] In the embodiments of this application, in order to facilitate the description of the technical solutions of the embodiments of this application, the terms "first" and "second" may be used for distinction. The terms "first" and "second" do not limit the quantity or execution order, and the terms "first" and "second" are not necessarily different.

[0065] In the embodiments of this application, the words "exemplary," "example," or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary," "example," or "for example" should not be construed as being more preferred or advantageous than other embodiments or designs. The use of the words "exemplary," "example," or "for example" is intended to present the relevant concepts in a specific manner to facilitate understanding.

[0066] In the embodiments of this application, "sending information / data" only indicates the direction of information / data transmission, including direct transmission through the device's communication interface (such as an air interface, or simply air interface). "Sending" can also be understood as the "output" of the module interface. "Sending" can include indirect transmission by the processing unit through the communication interface, that is, after the processing unit outputs information / data through the module interface, it is transmitted to the device's communication interface and then sent out. "Receiving information / data" only indicates the direction of information / data transmission, including direct reception through the communication interface. "Receiving" can also be understood as the "input" of the module interface. "Receiving information / data" can include indirect reception by the processing unit through the communication interface, that is, after the communication interface receives information / data, it is transmitted to the module interface of the processing unit and then input to the processing unit through the module interface. "Sending information / data to... (such as a terminal)" can be understood as the destination of the information being the terminal. It can include sending information / data directly or indirectly to the terminal. "Receiving information / data from... (such as a terminal)" can be understood as the source of the information being the terminal, and can include receiving information / data directly or indirectly from the terminal. Information / data may undergo necessary processing, such as format changes, between the source and destination, but the destination can understand the valid information / data from the source. Similar statements in the embodiments of this application can be understood in a similar way, and will not be repeated here.

[0067] The technical solutions of this application can be applied to various communication systems, such as Long Term Evolution (LTE) systems, 5th Generation (5G) communication systems, satellite communication systems, Wireless Fidelity (WiFi) systems, and the solutions provided in this application can also be applied to future communication systems or other communication systems. This application does not limit these applications.

[0068] Figure 1 This is a schematic diagram of the architecture of a communication system applicable to the communication method provided in the embodiments of this application. Figure 1 A schematic diagram of a possible, non-limiting system architecture is shown. (e.g.) Figure 1As shown, the communication system 100 includes a radio access network (RAN) 10 and a core network (CN) 20. Optionally, the communication system 100 also includes an Internet 30. The RAN 10 includes at least one RAN node (e.g., Figure 1 110a and 110b, collectively referred to as 110) and at least one terminal (such as Figure 1 RAN 10, denoted as RAN 120a-120j, is collectively referred to as RAN 120. RAN 10 may also include other RAN nodes, such as wireless relay equipment and / or wireless backhaul equipment. Figure 1 (Not shown in the image). Terminal 120 is connected to RAN node 110 wirelessly. RAN node 110 is connected to core network 20 wirelessly or via wired connection. The core network equipment in core network 20 and RAN node 110 in RAN 10 can be different physical devices, or they can be the same physical device integrating core network logical functions and radio access network logical functions.

[0069] RAN 10 can be a cellular system related to the 3rd Generation Partnership Project (3GPP), such as 4G, 5G mobile communication systems, or future-oriented evolution systems. RAN 10 can also be an open access network (O-RAN or ORAN), a cloud radio access network (CRAN), or a wireless fidelity (Wi-Fi) system. RAN 10 can also be a communication system that integrates two or more of the above systems.

[0070] RAN node 110, sometimes also referred to as access network equipment, RAN entity, or access node, is part of the communication system and is used to help terminals achieve wireless access. Multiple RAN nodes 110 in communication system 100 can be of the same type or different types. In some scenarios, the roles of RAN node 110 and terminal 120 are relative, for example... Figure 1 Network element 120i can be a helicopter or a drone, and it can be configured as a mobile base station. For terminals 120j that access RAN 10 through network element 120i, network element 120i is a base station; however, for base station 110a, network element 120i is a terminal. RAN node 110 and terminal 120 are sometimes referred to as communication devices, for example... Figure 1 Network elements 110a and 110b can be understood as communication devices with base station functions, while network elements 120a-120j can be understood as communication devices with terminal functions.

[0071] In one possible scenario, a RAN node can be a base station, an evolved NodeB (eNodeB), an access point (AP), a transmission reception point (TRP), a next-generation NodeB (gNB), a base station in a future mobile communication system, or an access node in a WiFi system, etc. Figure 1 110a), micro base stations or indoor stations (such as Figure 1 In CRAN scenarios, RAN nodes can be 110b, relay nodes, donor nodes, or wireless controllers. Optionally, RAN nodes can also be servers, wearable devices, vehicles, or in-vehicle equipment. For example, in vehicle-to-everything (V2X) technology, the access network equipment can be a roadside unit (RSU).

[0072] In another possible scenario, multiple RAN nodes collaborate to assist the terminal in achieving wireless access, with different RAN nodes each implementing a portion of the base station's functions. For example, RAN nodes can be central units (CUs), distributed units (DUs), CU-control plane (CPs), CU-user plane (UPs), or radio units (RUs), etc. CUs and DUs can be set up separately or included in the same network element, such as a baseband unit (BBU). RUs can be included in radio frequency equipment or radio frequency units, such as remote radio units (RRUs), active antenna units (AAUs), or remote radio heads (RRHs).

[0073] In different systems, CU (or CU-CP and CU-UP), DU, or RU may have different names, but those skilled in the art will understand their meaning. For example, in an ORAN system, CU can also be called O-CU (open CU), DU can also be called O-DU, CU-CP can also be called O-CU-CP, CU-UP can also be called O-CU-UP, and RU can also be called O-RU. For ease of description, this application uses CU, CU-CP, CU-UP, DU, and RU as examples in its embodiments. Any of the units among CU (or CU-CP, CU-UP), DU, and RU in the embodiments of this application can be implemented through software modules, hardware modules, or a combination of software modules and hardware modules.

[0074] A terminal can also be called a terminal device, user equipment (UE), mobile station, mobile terminal, etc. Terminals can be widely used in various scenarios, such as device-to-device (D2D), vehicle-to-everything (V2X) communication, machine-type communication (MTC), Internet of Things (IoT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grids, smart furniture, smart offices, smart wearables, smart transportation, smart cities, etc. Terminals can be mobile phones, tablets, computers with wireless transceiver capabilities, wearable devices, vehicles, drones, helicopters, airplanes, ships, robots, robotic arms, smart home devices, etc.

[0075] In this application embodiment, the terminal and network device can be hardware devices, or software functions running on dedicated hardware, or software functions running on general-purpose hardware, such as virtualization functions instantiated on a platform (e.g., cloud platform), or entities that include dedicated or general-purpose hardware devices and software functions. This application embodiment does not limit the specific form of the terminal and network device.

[0076] To better understand the methods provided in the embodiments of this application, the relevant technologies and terms involved in the embodiments of this application will be briefly explained below.

[0077] 1. Global Frequency Raster

[0078] A global frequency grid refers to the frequency domain spacing rules used to divide all frequency bands. Essentially, it is a set of predefined reference frequencies used to identify the frequency positions of channels, synchronization signals, and physical broadcast channel blocks (SSBs) or various reference points (such as point A).

[0079] For example, 5G New Radio (NR) supports a frequency range of 0-100 GHz. This 100 GHz band can be divided into 3,279,165 global frequency grids. Each global frequency grid is numbered as an absolute radio-frequency channel number (ARFCN), also known as a frequency point number, ranging from 0 to 3,279,165. Each ARFCN corresponds to a reference frequency (denoted as F). REF ), ARFCN and reference frequency F REF It satisfies the following formula (1):

[0080] F REF =N REF-Offs +ΔF Global ×(N REF -N REF-Offs ),

[0081] Where, N REF Represents ARFCN, N REF-Offs and F REF-Offs The offset constants for different frequency bands (which may be predefined by the protocol, but are not limited in this embodiment) ΔF Global This represents the global frequency grid, which can be, for example, 15kHz or 60kHz. The reference frequency F defined by the global frequency grid is... REF The relationship with ARFCN is shown in Table 1.

[0082] When ARFCN is between 0 and 599999, the corresponding frequency range is 0 to 3000 MHz, ΔF Global For 5kHz, F REF-Offs and N REF-Offs The value is 0. When ARFCN belongs to 600000-2016666, the corresponding frequency range is 3000~24250MHz, and ΔF is 0. Global For 15kHz, F REF-Offs For 300kHz, N REF-OffsThe frequency range is 600,000 kHz. When the ARFCN belongs to 2016667-3279165, the corresponding frequency range is 24,250 to 100,000 MHz, ΔF Global For 60kHz, F REF-Offs 24250.08kHz, N REF-Offs It is 2016667kHz.

[0083] Table 1

[0084] Frequency range (MHz) <![CDATA[ΔF Global (kHz)]]> <![CDATA[F REF-Offs (MHz)]]> <![CDATA[N REF-Offs ]]> <![CDATA[N REF Scope 0～3000 5 0 0 0-599999 3000～24250 15 300 600000 600000-2016666 24250～100000 60 24250.08 2016667 2016667-3279165

[0085] Taking ARFCN as 1500 as an example, the corresponding reference frequency is F. REF = 0 + 5kHz × (1500 - 0) = 7500kHz. The implementation method for determining the reference frequency when ARFCN is other values ​​is similar; for simplicity, examples will not be given here.

[0086] 2. Channel grid

[0087] The channel grid is a subset of the global frequency grid (or can be understood as the aforementioned set of reference frequencies) used to identify the frequency domain location of available channels (i.e., uplink or downlink channels) or the center frequency of a carrier. In other words, the channel grid, based on the global frequency grid, imposes range and compensation limitations on the reference frequencies according to the operating frequency band, indicating the selectable location of the carrier's center frequency within the corresponding operating frequency band.

[0088] 3. Synchronization signal and physical broadcast channel block (SSB)

[0089] The SSB (Secondary Signal Block) is a core signal block in the initial access process of a terminal in 5G NR, carrying very important functions such as carrying cell identifiers, time and frequency synchronization, and cell signal strength measurement. Network devices broadcast the SSB of each cell, enabling synchronization between the terminal and network devices. The terminal can then perform processes such as cell search, measurement, cell selection, or cell handover based on the SSB.

[0090] SSB includes primary synchronization signals (PSS), secondary synchronization signals (SSS), physical broadcast channel (PBCH), and demodulation reference signal (DMRS) of PBCH. Figure 2The time-frequency structure of the SSB is shown, as follows: Figure 2 The SSB shown occupies 4 consecutive orthogonal frequency division multiplexing (OFDM) symbols in the time domain and 20 consecutive resource blocks (RBs) in the frequency domain. Since each resource block contains 12 subcarrier resource elements (REs) in the frequency domain, the SSB occupies 240 subcarriers in the frequency domain, and the subcarriers are numbered k∈{0,1,2,…,239}.

[0091] The PBCH carries the master information block (MIB), which includes, but is not limited to, information used to determine the system frame number, system bandwidth, and subcarrier spacing. The terminal reads and attempts to decode the MIB carried on the PBCH in the SSB. Based on the MIB, the terminal determines the system frame number, system bandwidth, subcarrier spacing, etc. The terminal can also obtain the scheduling information of System Information Block (SIB) 1 based on the information provided by the MIB. Based on the scheduling information of SIB 1, the terminal can receive SIB 1. SIB 1 includes configuration information required for the terminal to access the cell, as well as system information (SI) scheduling information and other system information besides SIB 1.

[0092] 4. Synchronization raster

[0093] A synchronization grid is a specific frequency spacing rule followed by a terminal when searching for Service Serving Blocks (SSBs) in the frequency domain. Essentially, it's a predefined set of frequency points representing the possible frequency locations of SSBs. During power-on or handover, the terminal detects SSBs and synchronizes their establishment time and frequency with the cell, obtaining the cell identifier to provide a foundation for subsequent network access. During cell search, the terminal can scan potential frequency points based on the synchronization grid to locate SSBs (hereinafter referred to as the frequency scanning process).

[0094] The synchronization grid is numbered using the Global Synchronization Channel Number (GSCN), and each number corresponds to a frequency point of an SSB. The relationship between the synchronization grid and the GSCN is shown in Table 2:

[0095] Table 2

[0096]

[0097] As shown in Table 2, the range of GSCN is 2-7498 in the frequency range of 0-3000 MHz. Each GSCN corresponds to an N and an M, where N ranges from 1 to 2499 (i.e., N can be an integer from 1 to 2499), and M ∈ {1, 3, 5}. GSCN, N, and M satisfy the following formula (2):

[0098] GSCN = 3N + (M - 3) / 2.

[0099] GSCN corresponds to the synchronization signal frequency position SS REF This can also be called the center frequency of the synchronization signal, which can be determined based on GSCN corresponding to an N and an M, and the synchronization signal frequency position SS. REF N and M satisfy the following formula (3):

[0100] SS REF = N·1200kHz+M·50kHz.

[0101] For example, when N=1 and M=1, GSCN=3N+(1-3) / 2=2, and the synchronization signal frequency position is 1.1200kHz+1.50kHz=1250kHz. When N=1 and M=3, GSCN=3N+(3-3) / 2=3, and the synchronization signal frequency position is 1.1200kHz+3.50kHz=1350kHz. When N=1 and M=5, GSCN=3N+(5-3) / 2=4, and the synchronization signal frequency position is 1.1200kHz+5.50kHz=1450kHz.

[0102] When the frequency range is 3000-24250MHz or 24250-100000MHz, the relationship between the synchronization grid and GSCN can also be determined based on Table 2 above. For the sake of simplicity, examples are not given here.

[0103] Optionally, during the terminal's frequency scanning based on the synchronization grid, the terminal can also obtain at least one frequency with higher priority based on frequency-related information pre-set in the subscriber identity module (SIM) card (such as the frequency bands supported by the operator to which the SIM card belongs), or the terminal can obtain at least one frequency with higher priority based on information stored in the terminal's memory, such as the frequency point where the terminal last successfully camped and operator information (such as the public land mobile network (PLMN) identifier). The terminal prioritizes scanning these at least one frequency with higher priority to see if there is an SSB. This helps improve cell search efficiency.

[0104] 5. Non-terrestrial network (NTN)

[0105] Because traditional terrestrial networks cannot provide seamless coverage, especially in areas where base stations cannot be deployed, such as the ocean, deserts, and the air, non-terrestrial satellite communication networks (or NTNs) are considered an important aspect of future wireless communication technology development. Satellite communication refers to communication conducted by terrestrial radio communication equipment using satellite base stations as relays. A satellite communication system consists of a satellite component and a terrestrial component.

[0106] The orbital altitude of a satellite base station affects its coverage area and communication latency. The orbital altitude of a satellite base station can be categorized as follows:

[0107] Low Earth orbit (LEO) refers to an orbit with an altitude between approximately 300 and 1500 kilometers.

[0108] Medium Earth orbit (MEO): refers to an orbit with an altitude between 7,000 km and 25,000 km.

[0109] Geostationary orbit (GEO): refers to an orbit at an altitude of approximately 35,786 kilometers.

[0110] 6. Doppler effect

[0111] The Doppler effect refers to the phenomenon where the frequency of a wave perceived by an observer changes when there is relative motion between the wave source and the observer. When the wave source moves closer to the observer, the frequency of the wave received by the observer increases. When the wave source moves away from the observer, the frequency of the wave received by the observer decreases.

[0112] The Doppler effect may also exist in satellite communications. For example... Figure 3 As shown, for the downlink, the satellite base station can be understood as the wave source, and the terminal as the observer. When there is relative motion between the satellite base station and the terminal, there is a shift between the frequency received by the terminal from the satellite base station and the frequency transmitted by the satellite base station. This shift can be called the Doppler frequency offset, denoted as Δf. 多普勒估计 .

[0113] Specifically, when the satellite base station moves closer to the terminal (i.e., the distance between the satellite base station and the terminal decreases), due to the relative proximity between the wave source (satellite base station) and the observer (terminal), the frequency of the signal received by the terminal from the satellite base station is higher than the transmission frequency (Δf). 多普勒估计 >0). Similarly, when the satellite base station moves away from the terminal (i.e., the distance between the satellite base station and the terminal increases), due to the relative distance between the wave source (satellite base station) and the observer (terminal), the frequency of the signal received by the terminal from the satellite base station is lower than the transmission frequency (Δf).多普勒估计 <0).

[0114] The higher the relative speed of movement between the satellite base station and the terminal, the greater the Doppler frequency offset. In particular, LEO satellite base stations have an orbital altitude of approximately 300 to 1500 kilometers (relatively low orbital altitude), and the satellite base stations operate at high speeds, resulting in a greater speed of movement relative to the terminal (or the ground), thus leading to a larger Doppler frequency offset.

[0115] If the Doppler frequency offset exceeds the frequency deviation tolerance of the terminal (or its receiver), it may prevent the terminal (or its receiver) from properly demodulating the signal, affecting the reliability of communication. For example, for a LEO satellite base station at an orbital altitude of approximately 500 km, at a frequency of 2350 MHz and an elevation angle of 10 degrees from the ground, the maximum Doppler frequency offset can reach 54.5 kHz, affecting the terminal's demodulated signal.

[0116] Since motion is relative, there will also be Doppler frequency offset in the uplink, and the magnitude of the Doppler frequency offset in the uplink is the same or close to that in the downlink.

[0117] During the initial cell access process, the terminal sends access requests (such as random access preambles) to the base station to request access to the target cell. This information is carried on the uplink. If there is Doppler frequency offset in the uplink, the base station may be unable to correctly demodulate the access requests from the terminal, causing the terminal's initial cell access to fail and affecting the reliability of communication.

[0118] Therefore, during the initial access process of the terminal, Doppler pre-compensation is required for uplink communication. Specifically, the terminal can pre-calculate (or estimate) the Doppler frequency offset between the terminal and the satellite base station. Before the terminal sends a signal to the satellite base station, the terminal adjusts the transmission frequency point according to the determined Doppler frequency offset to cancel the possible Doppler frequency offset between the terminal and the satellite base station. This ensures that the satellite base station receives a signal with no or very small frequency offset, which helps the satellite base station to correctly demodulate the information from the terminal.

[0119] For example, as the satellite base station moves closer to the terminal (i.e., the distance between the satellite base station and the terminal decreases), assume that the terminal determines the actual Doppler frequency offset between the terminal and the satellite base station to be Δf. 多普勒估计 In other words, the frequency at which the satellite base station receives the uplink signal from the terminal is Δf higher than the terminal's transmitting frequency. 多普勒估计 Before transmitting a signal to the satellite base station, the terminal can lower the transmission frequency by Δf. 多普勒估计 This is to pre-compensate for potential Doppler frequency offset in the uplink.

[0120] The specific methods by which the terminal calculates (or estimates) the Doppler frequency offset between the terminal and the satellite base station may include, but are not limited to, the following methods 1, 2 and 3.

[0121] Method 1: The terminal obtains its geographical location information through the Global Navigation Satellite System (GNSS), and calculates (or estimates) the Doppler frequency offset based on the terminal's geographical location information and the satellite geographical information carried in the base station broadcast information. The specific process is as follows:

[0122] 1) The terminal's location coordinates (such as longitude, latitude, and altitude) and motion status (including speed and direction) are obtained via GNSS. The terminal also obtains the location and motion status (including speed and direction) of the satellite base station based on geographical information related to the satellite base station's location (such as satellite ephemeris information) carried in the base station's broadcast information.

[0123] 2) Based on the relative position and motion state between the terminal and the satellite base station, determine the relative velocity vector (denoted as v) between the terminal and the satellite base station. This relative velocity vector is the velocity component of the relative velocity in the direction of signal propagation.

[0124] 3) Calculate (estimate) the Doppler frequency offset based on the relative velocity vector, including the relative velocity vector v and the Doppler frequency offset Δf. 多普勒估计 satisfy:

[0125]

[0126] Where c is the speed of light (approximately 3 × 10⁻⁶). 8 f0 is the carrier frequency (m / s).

[0127] Based on the above process, the terminal can calculate (or estimate) the Doppler frequency offset Δf. 多普勒估计 And can be based on this Δf 多普勒估计 During the initial access process, the transmission frequency of the uplink signal is pre-compensated.

[0128] Method 2: The terminal obtains the terminal's geographical location information through the reference location carried in the broadcast information, and calculates (or estimates) the Doppler frequency offset based on the terminal's reference location and satellite geographical information.

[0129] In Method 2, the way the terminal calculates (or estimates) the Doppler frequency offset based on the terminal's reference location and the geographic information of the satellite base station is similar to that in Method 1, and will not be described again here.

[0130] Optionally, the satellite base station can determine the distance between the terminal and the satellite base station based on the signal transmission time (TOA) from the transmitter (i.e., the terminal) to the receiver (i.e., the satellite base station). The satellite base station can also measure the angle of arrival (AOA) to determine the signal propagation direction, and determine the terminal's geographical location based on this direction and the distance between the terminal and the satellite base station. However, these methods of locating terminals based on signal-based TOA or AOA are easily affected by factors such as the radio frequency or cell beam size, impacting the accuracy of base station-based terminal location. If the terminal calculates the Doppler frequency offset based on this inaccurate reference position, it may result in a significant error in the terminal's Doppler frequency offset.

[0131] Method 3: The terminal obtains the frequency offset estimate from the SSB frequency scanning, downlink synchronization, and system information decryption processes, and uses this frequency offset estimate as the Doppler frequency offset. The specific process is as follows:

[0132] 1) The terminal scans its supported frequency bands based on the synchronization grid to search for potential SSSs. Specifically, the terminal can perform correlation calculations on the received signals based on known PSSs. If the terminal detects a correlation peak at a certain frequency position that meets preset conditions (the preset conditions could be, for example, a preset threshold), it can be considered that a PSS has been detected at that frequency position, i.e., an SSS has been detected.

[0133] 2) During downlink synchronization, the terminal obtains a rough frequency offset estimate by comparing the phase difference between the received PSS and the known PSS sequence (e.g., the error range of the frequency offset estimate is ±500kHz).

[0134] Because the position of PSS in SSB is fixed (e.g.) Figure 2 As shown in the diagram, after determining the location of the PSS, the terminal can further determine the time-frequency location of other parts of the SSB (i.e., the SSS or PBCH) and demodulate the SSS to achieve more accurate time and frequency synchronization. Specifically, the terminal performs correlation operations between the received SSS sequence and the known SSS sequence to obtain a fine-grained frequency offset estimate.

[0135] Since the time-frequency structure of the SSB is fixed, after detecting the PSS and SSS, the terminal can determine the time-frequency position of the PBCH based on the SSB's time-frequency structure and begin demodulating the PBCH signal. Specifically, the terminal reads and attempts to decode the MIB carried on the PBCH in the SSB. Based on the MIB, the terminal determines the system frame number, system bandwidth, subcarrier spacing, etc. The terminal can also obtain the scheduling information of SIB1 based on the information provided by the MIB. Based on the scheduling information of SIB1, the terminal can receive SIB1 and also obtain SI scheduling information for other system information besides SIB1. During the decoding of system information, the terminal can obtain a more accurate frequency offset estimate, which is the Doppler frequency offset determined by the terminal.

[0136] It should be noted that the specific process of determining the Doppler frequency offset by the terminal shown in Method 3 above is only an exemplary description for the purpose of understanding the embodiments of this application, and is not a specific limitation on the embodiments of this application. In actual applications, the specific process of Method 3 may also include other steps. The specific method used by the terminal to determine the frequency offset estimate may be predefined by the protocol or pre-configured in the terminal. The embodiments of this application do not limit this.

[0137] In some scenarios, the frequency offset estimate obtained by the terminal from SSB frequency scanning, downlink synchronization, and system information decryption may have a significant error compared to the actual Doppler frequency offset. If the terminal directly approximates this frequency offset estimate as the transmission frequency point for Doppler frequency offset compensation in uplink communication, it may lead to pre-compensation failure. Furthermore, if the error is large, the frequency offset between the compensated uplink transmission frequency point and the receiving frequency may be even greater, causing the Doppler pre-compensation performed by the terminal to have a negative effect and impacting uplink demodulation performance. For ease of understanding, the following will combine... Figure 4 The reasons why there may be a large error between the frequency offset estimate obtained by the terminal and the actual Doppler frequency offset are explained.

[0138] As discussed earlier, the greater the moving speed of the satellite base station, the greater the actual Doppler frequency offset between the satellite base station and the terminal. This Doppler frequency offset causes a shift between the center frequency of the SSB actually detected by the terminal and the actual transmission frequency of the satellite SSB (which corresponds to the center frequency of the SSB actually transmitted by the satellite base station). If the Doppler frequency offset is large, the SSB may shift to a frequency adjacent to the actual transmission frequency. In this case, the terminal may detect correlation peaks at two or more adjacent GSCN frequency points during the frequency sweep process, meaning the terminal may detect the same SSB at two or more adjacent frequency points.

[0139] Figure 4The frequencies 2352.05MHz, 2352.15MHz, and 2352.25MHz shown are the center frequencies of the SSBs corresponding to GSCN numbers 5879, 5880, and 5881, respectively. Assuming the center frequency of the SSB transmitted by the satellite base station is 2352.15MHz (corresponding GSCN 5880), and the actual Doppler frequency offset between the terminal and the satellite base station is +60kHz, then the actual center frequency of the SSB after reaching the terminal is as follows: Figure 4 The frequency corresponding to the position of the dashed line in the figure (i.e., 2352.15MHz+60kHz) is also the center frequency of the SSB detected by the terminal.

[0140] It is understandable that the larger the Doppler frequency offset, the greater the offset of the signal to adjacent frequency points during transmission. The actual center frequency of this SSB after reaching the terminal is not only around 2352.15MHz, but also around 2352.25MHz. When the terminal performs correlation calculations on the signals received at these two frequency points based on the known PSS, it is highly likely that it can detect the correlation peak that meets the preset conditions. That is, the terminal can detect the SSB at both 2352.15MHz and 2352.25MHz.

[0141] If the terminal detects an SSB at frequency 2352.15MHz, and the center frequency of the detected SSB is 2352.15MHz + 60kHz, then the terminal determines the frequency offset estimate to be +60kHz. The terminal can use this +60kHz as the transmission frequency for Doppler frequency offset compensation uplink communication.

[0142] However, if the terminal detects an SSB at frequency 2352.25MHz, and the center frequency of the detected SSB is 2352.15MHz +60kHz, then the frequency offset estimated by the terminal is -40kHz, which differs from the actual Doppler frequency offset (+60kHz) between the terminal and the satellite base station by 100kHz. If the terminal still takes this -40kHz as the Doppler frequency offset, the frequency offset between the compensated uplink transmission frequency and the receiving frequency may be even greater.

[0143] Of the methods 1-3 for determining Doppler frequency offset shown above, method 1 is based on GNSS to obtain the terminal's position coordinates and motion status, and cannot be applied to terminals that do not support GNSS. In method 2, the Doppler frequency offset determined by the terminal based on a reference position may have a large error. In method 3, when the Doppler frequency offset is large, the terminal may detect SSBs at different frequency points (different sweep positions). For the same SSB, the frequency offset estimate determined by the terminal at different frequency points will be different. Among these different frequency offset estimates, there will be frequency offset estimates with large errors compared to the actual Doppler frequency offset. If the terminal uses the frequency offset estimate with large errors to compensate for the uplink communication transmission frequency point, it may cause a decrease in the demodulation performance of the uplink communication. In other words, method 3 is not suitable for situations with large Doppler frequency offsets (such as communication between LEO satellites and terminals in NTN communication systems).

[0144] Based on this, embodiments of this application propose that the terminal can determine the Doppler frequency offset based on the frequency offset estimate determined during the synchronization process and the frequency point indicated by the base station. In this way, the terminal can obtain a more accurate Doppler frequency offset without using GNSS. The terminal uses this more accurate Doppler frequency offset to compensate for the uplink signal transmission frequency point, which helps improve the accuracy of frequency offset compensation and enhances communication reliability.

[0145] The methods provided in the embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0146] It should be understood that the embodiments of this application can be applied to satellite communication scenarios, such as during the initial access of a terminal to an NTN cell or during handover to an NTN cell, and can also be applied to terrestrial communication scenarios. The embodiments of this application do not impose any limitations on these applications. The following describes the communication method provided by the embodiments of this application from the perspective of interaction between the terminal and the base station (the base station can be a satellite base station or a terrestrial base station), but the embodiments of this application do not limit the executing entity of the method. In each embodiment, the terminal's function can also be implemented by modules (such as chips, chip systems, processors, logic circuits, or software) configurable in (or used for) the terminal. In each embodiment, the base station's function can be implemented by the access network node described above. Alternatively, it can be implemented by modules (such as chips, chip systems, processors, logic circuits, or software) configurable in the base station. When the executing entity is a module in the terminal or base station, receiving / transmitting can be understood as input / output, that is, the module communicates with other modules or components of the terminal or base station. Furthermore, the operation performed by a single executing entity can also be divided into operations performed by multiple executing entities, which can be logically and / or physically separated. For example, the operation performed by the base station can be divided into operations performed by at least one of CU, DU, RU, etc.

[0147] Figure 5This is a schematic flowchart of a communication method provided in an embodiment of this application. The communication method may include, but is not limited to, the following steps S501-S504. Each step is described in detail below.

[0148] S501, the terminal detects the synchronization signal at the first frequency point and obtains the first frequency offset. The first frequency point is determined according to the synchronization grid. The first frequency offset is the frequency offset between the center frequency point of the detected synchronization signal and the first frequency point.

[0149] The specific synchronization grid can be referred to the previous description, and will not be repeated here. This application does not limit the method by which the terminal determines the sweep frequency point of the scanning synchronization signal based on the synchronization grid. For example, as shown in Table 2 above, the center frequency point of the synchronization signal defined by the synchronization grid is related to N and M. Therefore, the terminal can determine the potential SSB center frequency point for each possible combination of N and M within its supported frequency bands, and search for SSBs at or near the center frequency point of each potential SSB.

[0150] Taking a frequency range of 0-3000MHz as an example, the terminal can select an initial N value, and for the selected N, the terminal traverses all possible M values. Each combination of N and M can determine a potential SSB center frequency (N, M and the potential SSB center frequency satisfy the above formula (3)). The terminal can search for SSBs at or near the center frequency of the potential SSB.

[0151] After the terminal completes the scanning of all possible potential SSB center frequencies corresponding to M under the current N value, the terminal can continue scanning for all possible potential SSB center frequencies corresponding to M under the next N value, repeating the above process until the terminal's scanning range covers the frequency band supported by the terminal, or the terminal detects an SSB that meets preset conditions (such as signal strength meeting a signal strength threshold). When the frequency range is other than other frequency ranges, the terminal can determine the potential SSB center frequency based on the relationship between the synchronization grid and GSCN corresponding to other frequency ranges shown in Table 2. For simplicity, examples are not provided here.

[0152] Optionally, the terminal can select an initial N value or a next N value according to a preset rule. This preset rule may be predefined by the protocol, configured for the terminal by the network device through signaling, or pre-configured on the terminal. This application embodiment does not limit this.

[0153] If the terminal detects an SSB at a single frequency location, that frequency location is designated as the first frequency point. Alternatively, if the terminal detects an SSB at multiple frequency locations, it can select the frequency location carrying the stronger SSB signal as the first frequency point.

[0154] It should be noted that the above-described implementation of the terminal determining the first frequency point based on the synchronization grid is merely an exemplary description for the purpose of understanding the embodiments of this application, and is not intended to limit the embodiments of this application. In practical applications, the implementation of the terminal determining the first frequency point based on the synchronization grid can also be in other ways. For example, the terminal can also obtain at least one frequency point with higher priority based on frequency point related information preset in the SIM card or terminal memory information. This at least one frequency point belongs to the frequency point set predefined by the synchronization grid, and the terminal can scan this at least one frequency point preferentially.

[0155] The terminal detects a synchronization signal at a first frequency point and performs downlink synchronization based on the synchronization signal, obtaining the frequency offset (i.e., the first frequency offset) between the center frequency point of the detected synchronization signal and the first frequency point. This application embodiment does not limit the specific method by which the terminal obtains the first frequency offset. For example, the terminal can obtain the first frequency offset during the downlink synchronization process and the system information decoding process according to method 3 described above. It should also be understood that this application embodiment does not limit the first frequency offset obtained by the terminal to necessarily being the actual frequency offset between the center frequency point of the detected synchronization signal and the first frequency point. Due to limitations in terminal capabilities or other factors, the obtained first frequency offset can also be an approximation of the actual frequency offset, and this approximation of the actual frequency offset can also be applied to this application embodiment.

[0156] S502, the base station sends first information to the terminal, which is used to indicate the second frequency point.

[0157] Optionally, the base station can send first information to the terminal through system information. The first information can be system information or it can be carried on a system message block. For example, the first information can be carried on SIB1, or it can be carried on other system message blocks besides SIB1 (such as SIB19). The specific system message block on which the first information is carried can be predefined by the protocol or determined by the base station. This application embodiment does not limit this.

[0158] Specifically, after the terminal detects the PSS and / or SSS in the synchronization signal at the first frequency point, the terminal can determine the time-frequency position of the PBCH in the SSB. The terminal reads the MIB carried on the PBCH to determine the system frame number, system bandwidth, subcarrier spacing, etc., and the terminal can also obtain the scheduling information of SIB1 based on the information provided by the MIB. If the base station sends the first information to the terminal through SIB1, the terminal can obtain the first information according to the scheduling information of SIB1. Alternatively, if the base station sends the first information through other SIBs besides SIB1, the terminal can obtain the other SIBs according to the scheduling information of the other SIBs indicated by SIB1, and thus obtain the first information.

[0159] Accordingly, the terminal receives the first information from the base station and can determine the second frequency point based on the first information. The second frequency point is used by the terminal to determine the Doppler frequency offset (hereinafter referred to as the second frequency offset). After the terminal determines the second frequency point, the terminal can execute S503, that is, the terminal determines the second frequency offset based on the second frequency point and the first frequency offset.

[0160] It should be understood that the relative size of the numbers S501 and S502 above does not indicate the order of steps S501 and S502. When the first information is an SIB, this application does not limit the base station to sending the first information to the base station only after the terminal detects the synchronization signal. Since the SIB is sent periodically, the first information carried on the SIB is also periodically sent (or broadcast) to the terminal. After the terminal detects the synchronization signal, it can receive the next (or subsequent) first information broadcast by the base station based on the scheduling information of SIB1 or other SIBs.

[0161] The above-described implementation of the base station sending the first information to the terminal via system message blocks is merely an exemplary description for the purpose of understanding the embodiments of this application, and is not a specific limitation on the embodiments of this application. In practical applications, the base station can also send the first information to the terminal in other ways. For example, if the terminal needs to compensate for the uplink transmission frequency point during cell handover, the first information can be sent (or forwarded) to the terminal by a base station that has been synchronized with the terminal (such as the source base station during cell handover) through signaling (such as radio resource control (RRC) signaling). The embodiments of this application do not limit this.

[0162] Optionally, the second frequency point can be the center frequency point of the synchronization signal sent by the base station, or it can be a reference frequency point. Depending on the second frequency point, the implementation methods for the terminal to determine the Doppler frequency offset may also be different. The following describes various implementation methods for the terminal to determine the Doppler frequency offset, taking the second frequency point as the center frequency point of the synchronization signal sent by the base station or the second frequency point as the reference frequency point as examples. However, it should be understood that the embodiments of this application are not limited to this.

[0163] (a) The second frequency point is the center frequency point of the synchronization signal sent by the network device (such as the base station), and the second frequency deviation is the frequency deviation between the center frequency point of the synchronization signal detected by the terminal and the second frequency point.

[0164] Alternatively, this second frequency point can also be understood as the actual transmission frequency point at which the base station sends synchronization signals. As mentioned above... Figure 4 In the example shown, the center frequency of the synchronization signal transmitted by the base station is 2352.15MHz, and the second frequency is also 2352.15MHz.

[0165] The specific implementation of the first information indicating the second frequency point may include, but is not limited to, the following methods 1-3.

[0166] Method 1: The first information includes field A, which represents the second frequency point. In other words, the base station directly indicates the second frequency point to the terminal through the first information. For example, the base station can indicate the second frequency point to the terminal in Hertz (Hz), kilohertz (kHz), or megahertz (MHz). Assuming the base station indicates the second frequency point to the terminal in megahertz, and the center frequency of the synchronization signal transmitted by the base station is 2352.15MHz, then field A in the first information is 2352.15. Accordingly, after receiving the first information from the base station, the terminal can determine the second frequency point based on field A in the first information. For example, if the terminal determines the second frequency point to be 2352.15MHz based on field A being 2352.15.

[0167] The specific frequency unit used by the base station to indicate the second frequency point to the terminal can be predefined in the protocol, or it can be indicated by the base station to the terminal, such as the first information also including the frequency unit indication information of the second frequency point. Accordingly, after receiving the first information from the base station, the terminal can determine the second frequency point based on field A and the frequency unit indication information.

[0168] Method 2: The first information includes indication information for the second frequency point.

[0169] The indication information for the second frequency point can be, for example, the Global Synchronization Channel Number (GSCN) of the second frequency point, or it can be the Absolute Radio Frequency Channel Number (ARFCN) of the second frequency point. In other words, the base station indirectly indicates the second frequency point to the terminal through the GSCN or ARFCN.

[0170] In method 2-1, the first information includes field B, which represents the GSCN corresponding to the second frequency point (hereinafter referred to as the first GSCN for ease of description). The base station indirectly indicates the second frequency point to the terminal by indicating the first GSCN. Accordingly, after receiving the first information from the base station, the terminal can determine the first GSCN based on field B in the first information, and can determine the second frequency point based on the first GSCN. For example, if the center frequency of the synchronization signal transmitted by the base station is 2352.15MHz, and the GSCN corresponding to 2352.15MHz is 5880, then field B in the first information is 5880. Accordingly, after receiving the first information from the base station, the terminal determines the first GSCN as 5880 based on field B being 5880 in the first information, and can determine the second frequency point based on the first GSCN.

[0171] Optionally, the terminal can determine the second frequency point through the first GSCN based on the relationship between the synchronization grid and the GSCN shown in Table 2 above. Taking a frequency range of 0-3000MHz as an example, the terminal can first determine N and M according to the above formula (2) and the first GSCN, and then substitute the determined N and M into the above formula (3) to determine the second frequency point. For ease of understanding, the implementation method of determining N and M through GSCN is described below.

[0172] Optionally, based on the above formula (2) and the range of M being {1,3,5}, N is determined to satisfy:

[0173] When M = 1, N = (GSCN + 1) / 3.

[0174] When M=3, N=GSCN / 3.

[0175] When M = 5, N = (GSCN-1) / 3.

[0176] Specifically, after the terminal obtains the first GSCN, the terminal takes the modulo of the first GSCN with 3 and obtains the remainder of the first GSCN divided by 3.

[0177] When the remainder is 0, (M-3) / 2 equals 0, the terminal determines M=3, and can determine the N corresponding to the first GSCN according to N=GSCN / 3.

[0178] When the remainder is 1, (M-3) / 2 equals 1, the terminal determines M=5, and can determine the N corresponding to the first GSCN according to N=(GSCN-1) / 3.

[0179] When the remainder is 2, M = 1, and N corresponding to the first GSCN can be determined according to N = (GSCN + 1) / 3.

[0180] Furthermore, after the terminal determines N and M, the terminal can determine the second frequency point according to the above formula (3).

[0181] For example, if the first GSCN is 5880, the terminal can determine that N equals 1960 and M equals 0 according to the above method. Substituting N and M into the above formula (3), the second frequency point can be obtained as 2352.15MHz.

[0182] As shown in Table 2, when the frequency range is 3000-24250MHz or 24250-100000MHz, the GSCN is related to N, and the center frequency of the synchronization signal is also related to N. After receiving the first information from the base station, the terminal can determine the N corresponding to the first GSCN based on the first GSCN indicated by the first information and the correspondence between GSCN and N shown in Table 2, and then determine the center frequency of the synchronization signal based on the N corresponding to the first GSCN. For simplicity, this will not be elaborated further here.

[0183] It should be noted that the above-described implementation method of the terminal determining N and M based on GSCN and obtaining the second frequency point is only an exemplary description for the purpose of understanding the embodiments of this application, and is not a specific limitation on the embodiments of this application. In actual applications, after the terminal obtains the first GSCN, it can also determine the second frequency point corresponding to the first GSCN based on other methods.

[0184] For example, the protocol predefines or the terminal pre-configures a correspondence between GSCN and N, M (hereinafter referred to as the first correspondence). After obtaining the first GSCN, the terminal can filter a set of N and M corresponding to the first GSCN from the first correspondence. Furthermore, the terminal can determine the second frequency point based on the N and M.

[0185] For example, the protocol predefines or the terminal pre-configures a correspondence between the GSCN and the center frequency of the synchronization signal (hereinafter referred to as the second correspondence). After the terminal obtains the first GSCN, it can filter the second frequency point corresponding to the first GSCN in the second correspondence.

[0186] The specific method used by the terminal depends on the second frequency point determined by the first GSCN, which may be predefined by the protocol. This application does not limit this in the embodiments.

[0187] In method 2-2, the first information includes field C, which represents the ARFCN corresponding to the second frequency point (hereinafter referred to as the first ARFCN for ease of description). The base station indirectly indicates the second frequency point to the terminal by indicating the first ARFCN. Accordingly, after receiving the first information from the base station, the terminal can determine the first ARFCN based on field C in the first information, and can determine the second frequency point based on the first ARFCN.

[0188] Optionally, after determining the first ARFCN, the terminal can use the ARFCN and reference frequency F shown in Table 1 as a reference. REF The correspondence determines the reference frequency F corresponding to the first ARFCN. REF The reference frequency F REF This refers to the second frequency point. The embodiments of this application are not limited to this; how the terminal determines the second frequency point based on the ARFCN can be predefined by the protocol or pre-configured on the terminal. The embodiments of this application do not limit this. According to method 1, method 2-1, or method 2-2 described above, the terminal can determine the second frequency point. The specific method used by the base station to indicate the second frequency point to the terminal can be predefined by the protocol, or the protocol can predefine multiple implementation methods for the base station to indicate the second frequency point to the terminal. In practical applications, the base station can choose one of these methods and send the indication information of the second frequency point corresponding to that method to the terminal. The embodiments of this application do not limit this.

[0189] This application is not limited to this. The first information may also include the absoluteFrequencySSB field. The absoluteFrequencySSB field may also use ARFCN or GSCN to describe the center frequency of the synchronization signal. For details, please refer to the above description, which will not be repeated here.

[0190] Alternatively, the first information may also include at least one of the following: downlink frequency information (FrequencyInfoDL) structure field, downlink configuration (DownlinkConfigCommon) structure field, or serving cell configuration (ServingCellConfigCommon) structure field. These structure fields may also represent the center frequency of the synchronization signal, which will not be elaborated here.

[0191] Furthermore, after the terminal determines the second frequency point, the terminal can determine the second frequency offset (denoted as Δf2) based on the first frequency point (denoted as f1), the second frequency point (denoted as f2), and the first frequency offset (denoted as Δf1). This second frequency offset is the actual Doppler frequency offset (or an approximate value of the Doppler frequency offset) between the terminal and the base station.

[0192] It should be understood that the second frequency offset is specifically the frequency offset between the center frequency of the synchronization signal detected by the terminal and the second frequency. The terminal can then determine the center frequency of the synchronization signal detected by the terminal and determine the second frequency offset based on the center frequency and the second frequency of the detected synchronization signal. The center frequency of the synchronization signal detected by the terminal (i.e., the actual center frequency of the synchronization signal after it reaches the terminal) is f1 + Δf1. Therefore, the second frequency offset is specifically the offset between f1 + Δf1 and f2. Thus, the first frequency f1, the second frequency f2, the first frequency offset Δf1, and the second frequency offset Δf2 satisfy the following formula (4):

[0193] Δf2=f1+Δf1-f2.

[0194] To facilitate understanding, the following will be combined with... Figures 6 to 8 The implementation method for determining the second frequency offset of the terminal is further explained.

[0195] In one example, assuming the base station and the terminal are relatively far apart, the terminal receives a signal from the base station at a frequency lower than the transmission frequency. The center frequency of the synchronization signal shifts to a lower frequency. The terminal may detect the synchronization signal at a synchronization signal frequency that is adjacent to the second frequency f2 and has a lower frequency value than the second frequency, or it may detect the synchronization signal at the second frequency f2.

[0196] like Figure 6As shown, assuming the first frequency point f1 is a synchronization signal frequency point adjacent to the second frequency point f2 and with a frequency value smaller than the second frequency point, if the terminal detects a synchronization signal while scanning the first frequency point f1, and the terminal determines the first frequency offset to be Δf1 (Δf1 > 0), then the center frequency point of the synchronization signal detected by the terminal (i.e., the actual center frequency point of the synchronization signal after it reaches the terminal) is f1 + Δf1. The frequency offset between the center frequency point of the synchronization signal detected by the terminal and the second frequency point is f1 + Δf1 - f2.

[0197] like Figure 7 As shown, assuming the first frequency point f1 is the center frequency point of the synchronization signal transmitted by the base station, that is, the first frequency point f1 is the same as the second frequency point f2. If the terminal detects the synchronization signal when scanning the first frequency point f1, and the first frequency offset determined by the terminal is Δf1 (Δf1 < 0), then the center frequency point of the synchronization signal detected by the terminal (i.e., the actual center frequency point of the synchronization signal after it reaches the terminal) is f1 + Δf1. The frequency offset between the center frequency point of the synchronization signal detected by the terminal and the second frequency point is f1 + Δf1 - f2.

[0198] In another example, assuming the base station and the terminal are relatively close, the terminal receives a signal from the base station at a frequency higher than the transmitting frequency, and the center frequency of the synchronization signal shifts to a higher frequency. The terminal may detect the synchronization signal when scanning the synchronization signal frequency that is adjacent to the second frequency f2 and has a higher frequency value than the second frequency, or it may detect the synchronization signal when scanning the second frequency f2.

[0199] like Figure 8 As shown, assuming the first frequency point f1 is a synchronization signal frequency point adjacent to the second frequency point f2 and with a higher frequency value than the second frequency point, if the terminal detects a synchronization signal while scanning the first frequency point f1, and the terminal determines the first frequency offset to be Δf1 (Δf1 < 0), then the center frequency point of the synchronization signal detected by the terminal (i.e., the actual center frequency point of the synchronization signal after it reaches the terminal) is f1 + Δf1. The frequency offset between the center frequency point of the synchronization signal detected by the terminal and the second frequency point is f1 + Δf1 - f2.

[0200] like Figure 9 As shown, assuming the first frequency point f1 is the center frequency point of the synchronization signal transmitted by the base station, that is, the first frequency point f1 is the same as the second frequency point f2. If the terminal detects the synchronization signal when scanning the first frequency point f1, and the first frequency offset determined by the terminal is Δf1 (Δf1 > 0), then the center frequency point of the synchronization signal detected by the terminal (i.e., the actual center frequency point of the synchronization signal after it reaches the terminal) is f1 + Δf1. The frequency offset between the center frequency point of the synchronization signal detected by the terminal and the second frequency point is f1 + Δf1 - f2.

[0201] In other words, when f1 > f2, or f1 < f2, or f1 = f2, the first frequency point f1, the second frequency point f2, the first frequency deviation Δf1, and the second frequency deviation Δf2 all satisfy the above formula (4).

[0202] This application does not limit the method by which the terminal determines the second frequency offset Δf2 in practical applications. In one embodiment, the terminal can first obtain the center frequency of the synchronization signal detected by the terminal based on the first frequency point f1 and the first frequency offset Δf1, and then determine the second frequency offset Δf2 based on the center frequency of the detected synchronization signal and the second frequency point f2. In another embodiment, the terminal can directly determine the second frequency offset Δf2 based on the first frequency point f1, the second frequency point f2, the first frequency offset Δf1 and the above formula (4). The specific method used by the terminal to determine the second frequency offset Δf2 can be predefined by the protocol or pre-configured in the terminal, and this application does not limit this.

[0203] (ii) The second frequency point is the reference frequency point indicated by the base station.

[0204] Optionally, the reference frequency point is specifically the frequency point of point A. Point A is a reference point for frequency domain resource allocation. After the terminal obtains the frequency location of point A, it can further determine the time-frequency resources allocated to the terminal by the base station based on the frequency location of point A, so as to receive or transmit signals on the time-frequency resources.

[0205] The second frequency point is the frequency point of point A indicated by the base station. This frequency point of point A can also be called the absolute frequency point or absolute frequency position of point A.

[0206] When the second frequency point is the absolute frequency point of point A, the implementation of the first information indicating the second frequency point is similar to the implementation of the first information indicating the center frequency point of the synchronization signal transmitted by the base station, as shown above. For example, the base station can directly indicate the second frequency point to the terminal through field A in the first information. Accordingly, after receiving the first information from the base station, the terminal can determine the second frequency point based on field A in the first information. Alternatively, the base station can also indicate the ARFCN (hereinafter referred to as the second ARFCN) corresponding to the second frequency point to the terminal through field C in the first information. Accordingly, after receiving the first information from the base station, the terminal can determine the second ARFCN based on field C in the first information, and can determine the second frequency point based on the second ARFCN. For details, please refer to the relevant description above regarding the terminal determining the second frequency point based on the first ARFCN, which will not be repeated here.

[0207] This application is not limited to this. The first information may also include the absoluteFrequencyPointA field. The absoluteFrequencyPointA field may also use ARFCN to describe the absolute frequency of point A. For details, please refer to the description above, which will not be repeated here.

[0208] Alternatively, the first information may also include at least one of the following: downlink frequency information (FrequencyInfoDL) structure field, downlink common configuration (DownlinkConfigCommon) structure field, or serving cell common configuration (ServingCellConfigCommon) structure field. These structure fields may also represent the absolute frequency of point A, which will not be elaborated here.

[0209] To facilitate understanding, the following will be combined with... Figure 10 Explain the relationship between point A and SSB.

[0210] like Figure 10 As shown, point A points to the lowest subcarrier frequency of common resource block (CRB) 0 (i.e., the center position of subcarrier 0). The frequency of point A has a third frequency offset, a fourth frequency offset, and half the bandwidth of the synchronization signal (i.e., SSB) compared to the center frequency of the synchronization signal.

[0211] The third frequency offset is specifically the frequency offset between the reference frequency and the lowest subcarrier frequency of the common resource block containing the lowest subcarrier frequency of the synchronization signal. For example... Figure 10 As shown, the common resource block containing the lowest subcarrier frequency of the synchronization signal is the common resource block with the lowest frequency that coincides with (or intersects with) the synchronization signal in the frequency domain. The index of this common resource block is denoted as N_SSB_CRB. The third frequency offset is the frequency deviation between the lowest subcarrier frequency of this common resource block with index N_SSB_CRB and the reference frequency. Optionally, this third frequency offset can be represented by offsetToPointA in SIB1. For details on how the terminal receives SIB1, please refer to the relevant description above; it will not be repeated here.

[0212] The fourth frequency offset is the frequency offset between the lowest subcarrier frequency of the common resource block with index N_SSB_CRB and the lowest subcarrier frequency of the synchronization signal. This fourth frequency offset can be represented by ssb-SubcarrierOffset in the MIB. For details on how the terminal receives the MIB, please refer to the relevant description above, which will not be repeated here.

[0213] The bandwidth of the synchronization signal can be predefined by the protocol, or it can be indicated to the terminal by the base station through signaling, or it can be determined by the terminal based on the time-frequency structure of the synchronization signal, such as... Figure 2 As shown, if the protocol predefines that the synchronization signal occupies 20 consecutive RBs in the frequency domain, then the bandwidth of the synchronization signal is 20 RBs. Half of the synchronization signal bandwidth is 10 RBs.

[0214] Based on this, the terminal can determine the frequency of point A according to the center frequency, third frequency offset, fourth frequency offset, and bandwidth of the synchronization signal. Alternatively, the terminal can determine the center frequency of the synchronization signal according to the frequency of point A, third frequency offset, fourth frequency offset, and bandwidth of the synchronization signal.

[0215] After the terminal determines the second frequency point (i.e., the absolute frequency point of point A), it can determine the second frequency offset based on the second frequency point, the first frequency offset, the third frequency offset, and the fourth frequency offset. Specific implementation methods for the terminal to determine the second frequency offset may include, but are not limited to, the following implementation methods 1 and 2.

[0216] In implementation method 1, the terminal determines the center frequency of the synchronization signal sent by the base station based on the second frequency point, the third frequency offset, the fourth frequency offset, and the bandwidth of the synchronization signal.

[0217] according to Figure 10 As shown in the frequency domain relationship between point A (the second frequency point) and SSB, the lowest subcarrier frequency of the synchronization signal transmitted by the base station can be obtained through the second frequency point (denoted as f). A Adding the third frequency offset (denoted as Δf3) and the fourth frequency offset (denoted as Δf4), we obtain the center frequency (denoted as f2) of the synchronization signal transmitted by the base station. This center frequency can be obtained by adding the lowest subcarrier frequency of the synchronization signal transmitted by the base station to the bandwidth of the synchronization signal (denoted as B). ssb Half of ) is obtained, namely f2, f A , Δf3, Δf4, B ssb satisfy:

[0218] f2=f A +Δf3+Δf4+0.5B ssb .

[0219] Furthermore, after the terminal determines the center frequency point f2 of the synchronization signal sent by the base station, the terminal can determine the second frequency offset Δf2 based on the first frequency point f1, the center frequency point f2 of the synchronization signal sent by the network device, and the first frequency offset Δf1. This second frequency offset is the frequency offset between the detected center frequency point of the synchronization signal and the center frequency point of the synchronization signal sent by the network device. For example, f1, f2, Δf1, and Δf2 also satisfy the above formula (4), i.e.:

[0220] Δf2=f1+Δf1-f2.

[0221] Similar to the implementation method for determining the second frequency offset by the terminal shown above, the embodiments of this application do not limit the method by which the terminal determines the second frequency offset Δf2 in actual application.

[0222] In one embodiment, after the terminal determines the center frequency point f2 of the synchronization signal sent by the base station, the terminal can first obtain the center frequency point of the synchronization signal detected by the terminal by adding the first frequency point f1 to the first frequency point f1 and the first frequency offset Δf1, and then obtain the second frequency offset Δf2 by subtracting the center frequency point f2 of the synchronization signal sent by the base station from the center frequency point of the detected synchronization signal.

[0223] In another implementation, after the terminal determines the center frequency point f2 of the synchronization signal sent by the base station, the terminal can determine the second frequency offset Δf2 based on the first frequency point f1, the center frequency point f2 of the synchronization signal sent by the base station, the first frequency offset Δf1 and the above formula (4).

[0224] In another implementation, the second frequency point f A Third frequency offset Δf3, fourth frequency offset Δf4, bandwidth B of the synchronization signal ssb The first frequency point f1, the first frequency deviation Δf1, and the second frequency deviation Δf2 satisfy the following formula (5):

[0225] Δf2=f1+Δf1-(f A +Δf3+Δf4+0.5B ssb ).

[0226] Terminal obtains f A , Δf3, Δf4, B ssb After f1 and Δf1, the terminal can determine the value based on f. A , Δf3, Δf4, B ssb The second frequency offset Δf2 is determined by f1, Δf1, and the above formula 5.

[0227] The specific implementation method used by the terminal to determine the second frequency offset can be predefined by the protocol, and this application does not limit this aspect.

[0228] In implementation method 2, the terminal determines the lowest subcarrier frequency of the detected synchronization signal based on the first frequency point, the first frequency offset, and the bandwidth of the synchronization signal.

[0229] As mentioned earlier, the center frequency of the synchronization signal detected by the terminal is f1 + Δf1. The offset between the center frequency of the synchronization signal detected by the terminal (f1 + Δf1) and the lowest subcarrier frequency of the synchronization signal detected by the terminal is half of the synchronization signal bandwidth. Therefore, the lowest subcarrier frequency of the synchronization signal detected by the terminal is f1 + Δf1 - 0.5B. ssb .

[0230] Furthermore, the terminal determines the synchronization signal based on the lowest subcarrier frequency (f1 + Δf1 - 0.5B) of the detected synchronization signal. ssb The third frequency offset Δf3 and the fourth frequency offset Δf4 are used to obtain the reference frequency point determined by the terminal. Combined with... Figure 10 The reference frequency point determined by the terminal can be determined by the lowest subcarrier frequency of the synchronization signal (f1 + Δf1 - 0.5B). ssb Subtracting the third frequency offset Δf3 and then the fourth frequency offset Δf4, we get the reference frequency point determined by the terminal as f1 + Δf1 - 0.5B. ssb -Δf3-Δf4.

[0231] Furthermore, the terminal determines a second frequency offset based on the second frequency point and the reference frequency point determined by the terminal. This second frequency offset is the frequency difference between the reference frequency point determined by the terminal and the second frequency point (i.e., the reference frequency point indicated by the base station). The second frequency offset can be obtained by subtracting the second frequency offset from the reference frequency point determined by the terminal. That is, the reference frequency point determined by the terminal is f1 + Δf1 - 0.5B. ssb -Δf3-Δf4, the second frequency point f2, and the second frequency offset Δf2 satisfy the following formula (6):

[0232] Δf2=f1+Δf1-0.5B ssb -Δf3-Δf4-f2.

[0233] Alternatively, it can be understood as the first frequency point f1, the second frequency point f2, the first frequency offset Δf1, and the synchronization signal bandwidth B. ssb The second frequency offset Δf2, the third frequency offset Δf3 and the fourth frequency offset Δf4 satisfy the formula (6).

[0234] The above illustrates various implementation methods for determining the second frequency offset when the second frequency point is the center frequency point of the synchronization signal transmitted by the base station or a reference frequency point (such as point A). According to these implementation methods, the terminal can obtain the Doppler frequency offset (or an approximate value of the Doppler frequency offset) between the terminal and the base station. Specifically, whether the second frequency point is the center frequency point of the synchronization signal transmitted by the base station or a reference frequency point (such as point A) can be predefined by the protocol. Alternatively, the protocol can predefine multiple methods (i.e., the second frequency point can be either the center frequency point of the synchronization signal transmitted by the base station or a reference frequency point (such as point A)). In practical applications, the base station can select one of these methods and indicate to the terminal the indication information of the second frequency point under that method (this indication information is used to indicate whether the second frequency point is the center frequency point of the synchronization signal transmitted by the base station or a reference frequency point), as well as the frequency, GSCN, or ARFCN corresponding to the second frequency point. Correspondingly, after receiving the indication information of the second frequency point from the base station and the frequency, GSCN, or ARFCN corresponding to the second frequency point, the terminal can determine the second frequency point and use the implementation method corresponding to the second frequency point to determine the second frequency offset.

[0235] S504, the terminal sends second information to the base station. The transmission frequency of the second information is obtained after frequency offset compensation based on the second frequency offset.

[0236] Specifically, in the embodiment of determining the second frequency offset shown above, the second frequency offset is obtained by subtracting the frequency of the signal indicated by the base station (the transmission frequency of the synchronization signal or the reference frequency) from the frequency of the signal detected by the terminal (the center frequency of the synchronization signal detected by the terminal or the reference frequency determined by the terminal).

[0237] If the second frequency deviation is greater than 0, the signal will shift towards a higher frequency direction during transmission. In this case, the original transmission frequency of the terminal can be lowered to compensate for the signal shift towards a higher frequency direction during transmission. If the second frequency deviation is less than 0, the signal will shift towards a lower frequency direction during transmission. In this case, the original transmission frequency of the terminal can be raised to compensate for the signal shift towards a lower frequency direction during transmission.

[0238] Therefore, the transmission frequency of the second information (denoted as f) send ) can be obtained through the original transmission frequency point of the second information (denoted as f) send Subtracting the second frequency offset Δf2 from f') yields f, i.e. send f′ send And Δf2 satisfy:

[0239] f send =f′ send -Δf2.

[0240] However, the embodiments of this application are not limited to this. In the above-described embodiment for determining the second frequency offset, the second frequency offset is obtained by subtracting the frequency of the signal detected by the terminal (the center frequency of the synchronization signal detected by the terminal or the reference frequency determined by the terminal) from the frequency of the signal indicated by the base station (the transmission frequency or reference frequency of the synchronization signal). In this case, the above formula (4) can be replaced by: Δf2=f2-(f1+Δf1). The above formula (6) can be replaced by Δf2=f2+Δf3+Δf4+0.5B ssb -(f1+Δf1). In this case, if the second frequency deviation is greater than 0, the signal shifts towards a lower frequency during transmission, and the original transmission frequency of the terminal can be increased to compensate for this shift. If the second frequency deviation is less than 0, the signal shifts towards a higher frequency during transmission, and the original transmission frequency of the terminal can be decreased to compensate for this shift. That is, the transmission frequency of the second information (denoted as f1). send ) can be obtained through the original transmission frequency point of the second information (denoted as f) send Adding the second frequency offset Δf2 to f') yields f send f′ send And Δf2 satisfy:

[0241] f send =f′ send +Δf2.

[0242] When a specific terminal determines the second frequency offset, whether it obtains the second frequency offset by subtracting the frequency of the signal indicated by the base station from the frequency of the signal detected by the terminal, or by subtracting the frequency of the signal detected by the terminal from the frequency of the signal indicated by the base station, can be predefined in the protocol, and this application does not limit this.

[0243] According to the above scheme, the terminal can determine the actual Doppler frequency offset (or an approximate value of the Doppler frequency offset) between the terminal and the base station without using the terminal's geographical location information provided by GNSS. This can improve the accuracy of the terminal's frequency offset compensation and enhance the reliability of communication.

[0244] It should be noted that the formulas listed in the embodiments of this application contain multiple variable elements and composite operational structures, making it difficult to exhaustively list all possible formula variations through limited embodiments. However, those skilled in the art should understand that any formula expression obtained based on the same technical concept through equivalent variable substitution, adjustment of operational order, or algebraic identity transformation, as long as its core features do not depart from the design principles of the embodiments of this application, should be considered to fall within the protection scope of the embodiments of this application. Differences in the specific presentation of the formulas do not constitute a change to the substantial design principles of the embodiments of this application.

[0245] It is understood that, in order to achieve the functions in the above embodiments, the base station and terminal include hardware structures and / or software modules corresponding to perform each function. Those skilled in the art should readily recognize that, based on the units and method steps of the various examples described in conjunction with the embodiments disclosed in this application, the embodiments of this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed by hardware or by computer software driving hardware depends on the specific application scenario and design constraints of the technical solution.

[0246] Figure 11 and Figure 12 The diagram illustrates the possible structures of communication devices provided in embodiments of this application. These communication devices can be used to implement the functions of a base station or terminal in the above method embodiments, and thus also achieve the beneficial effects of the above method embodiments. In the embodiments of this application, the communication device may be as follows: Figure 1 The access network node shown can be as follows: Figure 1 One of the terminals 110a-110j shown can also be as follows: Figure 1 The access network node 110a or 110b shown can also be a unit / module / component (such as a chip, chip system, logic circuit or software) applied to the terminal or access network node.

[0247] The communication device 1100 includes a transceiver unit 1120, which can be used to receive or send information. The communication device 1100 may also include a processing unit 1110, which can be used to process instructions or data to achieve corresponding operations.

[0248] It should be understood that when the communication device 1100 is a chip configured in (or used in) a communication device, the transceiver unit 1120 in the communication device 1100 can be the input / output interface or circuit of the chip, and the processing unit 1110 in the communication device 1100 can be the processor in the chip.

[0249] Optionally, the communication device 1100 may further include a storage unit 1120, which can be used to store instructions or data. The processing unit 1110 can execute the instructions or data stored in the storage unit to enable the communication device to perform corresponding operations.

[0250] The communication device 1100 can be used to achieve the above. Figure 5 The terminal functionality is shown in the method embodiment illustrated.

[0251] When the communication device 1100 is used to implement Figure 5In the illustrated method embodiment, the terminal functions as follows: A processing unit 1110 is configured to detect a synchronization signal at a first frequency point and obtain a first frequency offset. The first frequency point is determined based on a synchronization grid, and the first frequency offset is the frequency offset between the detected center frequency point of the synchronization signal and the first frequency point. A transceiver unit 1120 is configured to receive first information, which indicates a second frequency point. The processing unit 1110 is further configured to determine a second frequency offset based on the second frequency point and the first frequency offset. The transceiver unit 1120 is further configured to transmit second information, the transmission frequency of which is obtained after frequency offset compensation based on the second frequency offset.

[0252] Optionally, the second frequency point is the center frequency point of the synchronization signal sent by the network device, and the second frequency offset is the frequency offset between the detected center frequency point and the second frequency point of the synchronization signal.

[0253] Optionally, the processing unit 1110 is further configured to determine the second frequency offset based on the first frequency point, the second frequency point, and the first frequency offset.

[0254] Optionally, the second frequency point is a reference frequency point indicated by the network device. The processing unit 1110 is further configured to determine the second frequency offset based on the second frequency point, the first frequency offset, the third frequency offset, and the fourth frequency offset, wherein the third frequency offset is the common frequency between the reference frequency point and the lowest subcarrier frequency of the synchronization signal.

[0255] The frequency offset between the lowest subcarrier frequencies of the shared resource blocks, and the fourth frequency offset is the frequency offset between the lowest subcarrier frequency of the synchronization signal and the lowest subcarrier frequency of the shared resource block where the lowest subcarrier frequency of the synchronization signal is located.

[0256] Optionally, the processing unit 1110 is further configured to determine the center frequency of the synchronization signal transmitted by the network device based on the second frequency point, the third frequency offset, the fourth frequency offset, and the bandwidth of the synchronization signal; and to determine the second frequency offset based on the first frequency point, the center frequency of the synchronization signal transmitted by the network device, and the first frequency offset, wherein the second frequency offset is the frequency offset between the detected center frequency of the synchronization signal and the center frequency of the synchronization signal transmitted by the network device.

[0257] Optionally, the first frequency point f1, the center frequency point f2 of the synchronization signal transmitted by the network device, the first frequency offset Δf1, and the second frequency offset Δf2 satisfy:

[0258] Δf2=f1+Δf1-f2.

[0259] Optionally, the processing unit 1110 is further configured to determine the lowest subcarrier frequency of the detected synchronization signal based on the first frequency point, the first frequency offset, and the bandwidth of the synchronization signal; obtain the reference frequency point determined by the terminal based on the lowest subcarrier frequency of the detected synchronization signal, the third frequency offset, and the fourth frequency offset; and determine the second frequency offset based on the second frequency point and the reference frequency point determined by the terminal, wherein the second frequency offset is the frequency offset between the reference frequency point determined by the terminal and the second frequency point.

[0260] Optionally, the first frequency point f1, the second frequency point f2, the first frequency offset Δf1, and the synchronization signal bandwidth B are... ssb The second frequency offset Δf2, the third frequency offset Δf3, and the fourth frequency offset Δf4 satisfy the following:

[0261] Δf2=f1+Δf1-0.5B ssb -Δf3-Δf4-f2.

[0262] Optionally, the first information includes at least one of the following corresponding to the second frequency point: a global synchronization channel number; or an absolute radio frequency channel number.

[0263] For a more detailed description of the aforementioned processing unit 1110 and transceiver unit 1120, please refer to [reference needed]. Figure 5 The relevant descriptions in the method embodiments shown.

[0264] When the communication device 1100 is used to implement Figure 5 In the method embodiment shown, the base station functions as follows: transceiver unit 1120 is used to send a synchronization signal; transceiver unit 1120 is also used to send first information, the first information being used to indicate a second frequency point, wherein the synchronization signal and the second frequency point are used by the terminal to determine the frequency offset for frequency offset compensation of uplink information.

[0265] Optionally, the second frequency point is the center frequency point of the synchronization signal; or, the second frequency point is the reference frequency point.

[0266] Optionally, the first information includes at least one of the following corresponding to the second frequency point: a global synchronization channel number; or an absolute radio frequency channel number.

[0267] For a more detailed description of the aforementioned processing unit 1110 and transceiver unit 1120, please refer to [reference needed]. Figure 5 The relevant descriptions in the method embodiments shown.

[0268] It is understood that the division of units in the above-described device is merely a logical functional division. Each function can correspond to a functional unit, or two or more functions can be integrated into one functional unit. In actual implementation, all or some units can be integrated into a single physical entity, or they can be distributed across different physical entities. Furthermore, the aforementioned functional units can be implemented in hardware, software, or a combination of both. Whether a function is executed in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0269] like Figure 12 As shown, the communication device 1200 includes a processor 1210 and an interface circuit 1220. The processor 1210 and the interface circuit 1220 are coupled to each other. It is understood that the interface circuit 1220 can be a transceiver or an input / output interface. Optionally, the communication device 1200 may also include a memory 1230 for storing instructions executed by the processor 1210, or storing input data required by the processor 1210 to execute instructions, or storing data generated after the processor 1210 executes instructions.

[0270] In one implementation, the memory 1230 may be integrated into the processor 1210 or independent of the processor 1210.

[0271] When the communication device 1200 is used to implement Figure 5 In the method shown, processor 1210 is used to implement the functions of the processing unit 1110, and interface circuit 1220 is used to implement the functions of the transceiver unit 1120.

[0272] When the aforementioned communication device is a chip applied to a terminal device, the terminal device chip can implement the functions of the terminal in the above method embodiments. The terminal device chip receives information from other modules (such as an RF module or antenna) in the terminal device, the information being sent to the terminal device by the network device; or, the terminal device chip sends information to other modules (such as an RF module or antenna) in the terminal device, the information being sent to the network device by the terminal device.

[0273] When the aforementioned communication device is a module applied to a network device, the network device module can implement the functions of the network device in the above method embodiments. The network device module receives information from other modules (such as radio frequency modules or antennas) in the network device, which is information sent from the terminal device to the network device; or, the network device module sends information to other modules (such as radio frequency modules or antennas) in the network device, which is information sent from the network device to the terminal device. Here, the network device module can be the baseband chip of the network device, or it can be a DU or other modules. The DU here can be a DU under an open radio access network (O-RAN) architecture.

[0274] It is understood that the processor in the embodiments of this application can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. A general-purpose processor can be a microprocessor or any conventional processor.

[0275] The method steps in the embodiments of this application can be implemented in hardware or in software instructions executable by a processor. The software instructions can consist of corresponding software modules, which can be stored in random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, registers, hard disks, portable hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. The storage medium can also be a component of the processor. The processor and storage medium can reside in an ASIC. Alternatively, the ASIC can reside in an access network device or a terminal device. The processor and storage medium can also exist as discrete components in the access network device or terminal device.

[0276] According to the method provided in the application embodiments, this application embodiment also provides a computer program product, the computer program product comprising: computer program code, which, when executed by one or more processors, causes a device including the processor to perform as described above. Figure 5 The method shown.

[0277] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. This 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 this application are performed, in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, network equipment, user equipment, or other programmable device.

[0278] According to the method provided in the embodiments of this application, the embodiments of this application also provide a computer-readable storage medium that stores the aforementioned computer program or instructions. When the computer program or instructions are executed by one or more processors, they cause a device including the processor to perform actions such as... Figure 5 The method shown.

[0279] As described above, computer programs or instructions can be stored in or transferred from one computer-readable storage medium to another. For example, the computer programs or instructions can be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; it can also be an optical medium, such as a digital video optical disc; or it can be a semiconductor medium, such as a solid-state drive. The computer-readable storage medium can be a volatile or non-volatile storage medium, or it can include both volatile and non-volatile types of storage media.

[0280] According to the method provided in the embodiments of this application, the embodiments of this application also provide a communication system, including one or more of the aforementioned network devices. The system may further include one or more of the aforementioned first terminals.

[0281] In the various embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatuses described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the couplings or direct couplings or communication connections shown or discussed may be through some interfaces; indirect couplings or communication connections between apparatuses or units may be electrical, mechanical, or other forms.

[0282] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this solution according to actual needs.

[0283] In the various embodiments of this application, unless otherwise specified or in case of logical conflict, the terminology and / or descriptions of different embodiments are consistent and can be referenced by each other. The technical features of different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0284] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A communication method, characterized in that, The method includes: The synchronization signal is detected at a first frequency point to obtain a first frequency offset. The first frequency point is determined based on the synchronization grid. The first frequency offset is the frequency offset between the center frequency point of the detected synchronization signal and the first frequency point. Receive first information, which is used to indicate the second frequency point; The second frequency offset is determined based on the second frequency point and the first frequency offset; The second information is sent, and the transmission frequency of the second information is obtained after frequency offset compensation based on the second frequency offset.

2. The method according to claim 1, characterized in that, The second frequency point is the center frequency point of the synchronization signal sent by the network device, and the second frequency offset is the detected frequency offset between the center frequency point of the synchronization signal and the second frequency point.

3. The method according to claim 2, characterized in that, The step of determining the second frequency offset based on the second frequency point and the first frequency offset includes: The second frequency offset is determined based on the first frequency point, the second frequency point, and the first frequency offset.

4. The method according to claim 3, characterized in that, The second frequency point is the reference frequency point indicated by the network device. The step of determining the second frequency offset based on the second frequency point and the first frequency offset includes: The second frequency offset is determined based on the second frequency point, the first frequency offset, the third frequency offset, and the fourth frequency offset. The third frequency offset is the frequency offset between the reference frequency point and the lowest subcarrier frequency of the common resource block where the lowest subcarrier frequency of the synchronization signal is located, and the fourth frequency offset is the frequency offset between the lowest subcarrier frequency of the common resource block and the lowest subcarrier frequency of the synchronization signal.

5. The method according to claim 4, characterized in that, Determining the second frequency offset based on the second frequency point, the first frequency offset, the third frequency offset, and the fourth frequency offset includes: The center frequency of the synchronization signal transmitted by the network device is determined based on the second frequency point, the third frequency offset, the fourth frequency offset, and the bandwidth of the synchronization signal. The second frequency offset is determined based on the first frequency point, the center frequency point of the synchronization signal sent by the network device, and the first frequency offset. The second frequency offset is the frequency offset between the detected center frequency of the synchronization signal and the center frequency of the synchronization signal sent by the network device.

6. The method according to claim 3 or 5, characterized in that, The first frequency point f1, the center frequency point f2 of the synchronization signal sent by the network device, the first frequency offset Δf1, and the second frequency offset Δf2 satisfy: Δf2=f1+Δf1-f2.

7. The method according to claim 4, characterized in that, Determining the second frequency offset based on the second frequency point, the first frequency offset, the third frequency offset, and the fourth frequency offset includes: Based on the first frequency point, the first frequency offset, and the bandwidth of the synchronization signal, determine the lowest subcarrier frequency of the detected synchronization signal; The reference frequency point determined by the terminal is obtained based on the lowest subcarrier frequency of the detected synchronization signal, the third frequency offset, and the fourth frequency offset. The second frequency offset is determined based on the second frequency point and the reference frequency point determined by the terminal. Wherein, the second frequency offset is the frequency offset between the reference frequency point determined by the terminal and the second frequency point.

8. The method according to claim 7, characterized in that, First frequency point f1, second frequency point f2, first frequency offset Δf1, synchronization signal bandwidth B ssb The second frequency offset Δf2, the third frequency offset Δf3, and the fourth frequency offset Δf4 satisfy the following: Δf2=f1+Δf1-0.5B ssb -Δf3-Δf4-f2。 9. The method according to any one of claims 1 to 8, characterized in that, The first information includes at least one of the following corresponding to the second frequency point: Global synchronization channel number; or, absolute radio frequency channel number.

10. A communication method, characterized in that, The method includes: Send synchronization signal; Send a first message, which is used to indicate a second frequency point, wherein the synchronization signal and the second frequency point are used by the terminal to determine the frequency offset for frequency offset compensation of uplink information.

11. The method according to claim 10, characterized in that, The second frequency point is the center frequency point of the synchronization signal; or, the second frequency point is the reference frequency point.

12. The method according to claim 10 or 11, characterized in that, The first information includes at least one of the following corresponding to the second frequency point: Global synchronization channel number; or, absolute radio frequency channel number.

13. A communication device, characterized in that, The device includes a processor coupled to a memory for storing a computer program, the processor executing the computer program stored in the memory to cause the communication device to perform the method as claimed in any one of claims 1 to 9; or to cause the communication device to perform the method as claimed in any one of claims 10 to 12.

14. A communication device, characterized in that, It includes a processor and a communication interface, the processor being configured to control the communication interface to implement the method as described in any one of claims 1 to 9; or to implement the method as described in any one of claims 10 to 12.

15. A computer-readable storage medium, characterized in that, The computer stores instructions that, when executed on a computer, cause the computer to perform the method as described in any one of claims 1 to 9, or cause the computer to perform the method as described in any one of claims 10 to 12.

16. A computer program product, characterized in that, The computer program product includes: a computer program that, when run, causes a computer to perform the method of any one of claims 1 to 9, or causes a computer to perform the method of any one of claims 10 to 12.

17. A communication system, characterized in that, It includes a first communication device and a second communication device, wherein the first communication device is used to perform the method as described in any one of claims 1 to 9, and the second communication device is used to perform the method as described in any one of claims 10 to 12.

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