Uplink time offset and / or frequency offset estimation method and device, electronic equipment and medium

Abstract

The embodiment of the invention provides an uplink time offset and / or frequency offset estimation method and device, electronic equipment and a medium, and relates to the technical field of wireless communication, and the technical scheme of the embodiment of the invention comprises the following steps: a terminal receives a Chirp signal sent by a non-ground network node, and carries out uplink time offset and / or frequency offset estimation on the basis of the Chirp signal; and determining a downlink time offset estimation value and a downlink frequency offset estimation value of a downlink between the non-ground network node and the terminal. And then the terminal determines an uplink time offset estimation value according to a corresponding relationship between the downlink time offset estimation value and an uplink time offset estimation value of an uplink between the non-ground network node and the terminal, and / or determines an uplink frequency offset estimation value according to a corresponding relationship between the downlink frequency offset estimation value and an uplink frequency offset estimation value of the uplink. Therefore, the time offset and / or the frequency offset of the uplink between the non-ground network node and the terminal is estimated.

Description

Technical Field

[0001] The present application relates to the field of wireless communication technologies, and particularly to a method, apparatus, electronic device, and medium for estimating uplink time offset and / or frequency offset. Background Art

[0002] Since non-terrestrial network communication systems have characteristics such as wide coverage, little influence from terrain factors, and little influence from natural disasters, the coverage of non-terrestrial network communication systems is wide. That is, they can not only cover the areas that can be covered by terrestrial communication systems, but also cover remote mountainous areas, the air, and the far sea areas that are difficult to cover by terrestrial communication networks. Therefore, non-terrestrial network communication systems and terrestrial communication systems can form a good complementary relationship. With the continuous development of non-terrestrial network communication systems, users' requirements for the communication quality of non-terrestrial network communication systems are also gradually increasing.

[0003] In a non-terrestrial network communication system, due to the high-speed movement of non-terrestrial network nodes relative to terminals, the signals received by non-terrestrial network nodes have obvious Doppler frequency shifts and large time delays, resulting in a large uplink frequency deviation in the uplink between non-terrestrial network nodes and terminals, abbreviated as uplink frequency offset, that is, there is a large frequency deviation between the signal carrier received by non-terrestrial network nodes and the signal carrier transmitted by terminals. For example, when a low-earth orbit satellite uses the satellite communication frequency band to transmit signals to a terminal, the Doppler frequency shift in the signals received by the low-earth orbit satellite is relatively high, resulting in the inability to correctly demodulate the received signals. In addition, due to the instability of the local clock of the terminal, there are time-frequency deviation changes between the terminal and non-terrestrial nodes, resulting in a large uplink frequency deviation and uplink time deviation in the uplink between non-terrestrial network nodes and terminals, that is, there are time deviation and frequency deviation between the signals transmitted by the terminal and the signals received by non-terrestrial network nodes. Among them, the uplink time deviation is the deviation between the time when the terminal transmits the signal and the time when the non-terrestrial network node receives the signal, abbreviated as uplink time offset. Therefore, the terminal needs to continuously estimate the time offset and / or frequency offset of the uplink in order to effectively establish a communication link between the terminal and non-terrestrial network nodes and achieve reliable data transmission.

[0004] Different from terrestrial communication systems, non-terrestrial network communication systems have characteristics such as long signal transmission distance, wide beam coverage, high relative movement speed, and limited payload. Therefore, the time-frequency offset estimation technologies in existing terrestrial communication systems cannot be applied to non-terrestrial network communication systems. Therefore, how to estimate the time offset and / or frequency offset of the uplink between non-terrestrial network nodes and terminals, so as to use the uplink time offset estimation value and / or uplink frequency offset estimation value to compensate the time and / or frequency of the uplink, enabling the terminal to communicate with non-terrestrial network nodes quickly and accurately, is an urgent problem to be solved. Summary of the Invention

[0005] The purpose of the embodiments of the present application is to provide a method, apparatus, electronic device, and medium for estimating uplink time offset and / or frequency offset, so as to estimate the time offset and / or frequency offset of the uplink between a non-terrestrial network node and a terminal. The specific technical solutions are as follows:

[0006] In the first aspect of the embodiments of the present application, a method for estimating uplink time offset and / or frequency offset is provided, which is applied to a terminal. The method includes:

[0007] Receiving a Chirp signal sent by a non-terrestrial network node;

[0008] Based on the Chirp signal, determining a downlink time offset estimation value and a downlink frequency offset estimation value of the downlink between the non-terrestrial network node and the terminal;

[0009] According to the corresponding relationship between the downlink time offset estimation value and the uplink time offset estimation value of the uplink between the non-terrestrial network node and the terminal, determining the uplink time offset estimation value, and / or according to the corresponding relationship between the downlink frequency offset estimation value and the uplink frequency offset estimation value of the uplink, determining the uplink frequency offset estimation value.

[0010] Optionally, the receiving the Chirp signal sent by the non-terrestrial network node includes:

[0011] Receiving the Chirp signal broadcast by the non-terrestrial network node through a frequency correction channel.

[0012] Optionally, the frequency modulation slope and pulse width of the Chirp signal are determined in the following manner:

[0013] Obtaining a preset frequency sweep range and processing gain;

[0014] Based on the frequency sweep range and the processing gain, determining the pulse width of the Chirp signal;

[0015] According to the processing gain and the pulse width, determining the frequency modulation slope of the Chirp signal.

[0016] Optionally, the based on the frequency sweep range and the processing gain, determining the pulse width of the Chirp signal includes:

[0017] Taking the ratio of the processing gain to the frequency sweep range as the pulse width of the Chirp signal;

[0018] The according to the processing gain and the pulse width, determining the frequency modulation slope of the Chirp signal includes:

[0019] Determine the square value of the pulse width, and use the ratio of the processing gain to the square value as the frequency modulation slope of the Chirp signal.

[0020] Optionally, determining the downlink time offset estimation value and the downlink frequency offset estimation value of the downlink between the non-terrestrial network node and the terminal based on the Chirp signal includes:

[0021] Obtain a local frequency sweep signal, and determine the correlation signal between the local frequency sweep signal and the Chirp signal, where the local frequency sweep signal is the same as the Chirp signal when it is transmitted;

[0022] Determine the peak frequency of the correlation signal, and based on the peak frequency, determine the first time offset estimation value and the first frequency offset estimation value between the Chirp signal when it is transmitted and when it is received;

[0023] Based on the first time offset estimation value, determine the downlink time offset estimation value, and based on the first frequency offset estimation value, determine the downlink frequency offset estimation value.

[0024] Optionally, the local frequency sweep signal includes a local up frequency sweep signal and a local down frequency sweep signal; determining the correlation signal between the local frequency sweep signal and the Chirp signal includes:

[0025] Multiply the local up frequency sweep signal by the Chirp signal to obtain a first correlation signal;

[0026] Multiply the local down frequency sweep signal by the Chirp signal to obtain a second correlation signal.

[0027] Optionally, determining the peak frequency of the correlation signal includes:

[0028] Perform a fast Fourier transform on the first correlation signal to obtain the frequency corresponding to the largest amplitude in the first correlation signal as the first peak frequency;

[0029] Perform a fast Fourier transform on the second correlation signal to obtain the frequency corresponding to the largest amplitude of the second correlation signal as the second peak frequency.

[0030] Optionally, the first frequency offset estimation value is:

[0031] f d =(f1 + f2) / 2

[0032] where f d is the first frequency offset estimation value, f1 is the first peak frequency, and f2 is the second peak frequency;

[0033] The first time offset estimation value is:

[0034] t d = (f2 - f1) / (2 * μ)

[0035] where t d is the first time offset estimation value, and μ is the frequency modulation slope of the Chirp signal.

[0036] Optionally, before determining the downlink time offset estimation value based on the first time offset estimation value and determining the downlink frequency offset estimation value based on the first frequency offset estimation value, it includes:

[0037] Receiving the downlink signal sent by the non-terrestrial network node to the terminal and obtaining the downlink pilot sequence included in the downlink signal;

[0038] Determining a second time offset estimation value and a second frequency offset estimation value between when the downlink signal is sent and when it is received according to the downlink pilot sequence;

[0039] The determining the downlink time offset estimation value based on the first time offset estimation value and determining the downlink frequency offset estimation value based on the first frequency offset estimation value includes:

[0040] Determining the downlink time offset estimation value based on the first time offset estimation value and the second time offset estimation value;

[0041] Determining the downlink frequency offset estimation value based on the first frequency offset estimation value and the second frequency offset estimation value.

[0042] Optionally, the determining the second time offset estimation value and the second frequency offset estimation value between when the downlink signal is sent and when it is received according to the downlink pilot sequence includes:

[0043] Obtaining a local pilot sequence, which is the same as the downlink pilot sequence when it is sent;

[0044] Multiplying the downlink pilot sequence and the local pilot sequence to obtain a pilot correlation signal and determining the autocorrelation peak frequency of the pilot correlation signal;

[0045] Determining the second time offset estimation value and the second frequency offset estimation value according to the autocorrelation peak frequency.

[0046] Optionally, the determining the downlink time offset estimation value based on the first time offset estimation value and the second time offset estimation value includes:

[0047] Taking the sum of the first time offset estimation value and the second time offset estimation value as the downlink time offset estimation value;

[0048] Determining the downlink frequency offset estimate based on the first frequency offset estimate and the second frequency offset estimate includes:

[0049] Taking the sum of the first frequency offset estimate and the second frequency offset estimate as the downlink frequency offset estimate.

[0050] Optionally, determining the uplink timing offset estimate according to the corresponding relationship between the downlink timing offset estimate and the uplink timing offset estimate of the uplink between the non-terrestrial network node and the terminal includes:

[0051] Taking twice the downlink timing offset estimate as the uplink timing offset estimate;

[0052] Determining the uplink frequency offset estimate according to the corresponding relationship between the downlink frequency offset estimate and the uplink frequency offset estimate of the uplink includes:

[0053] Taking the downlink frequency offset estimate as the uplink frequency offset estimate.

[0054] Optionally, after determining the uplink frequency offset estimate according to the corresponding relationship between the downlink frequency offset estimate and the uplink frequency offset estimate of the uplink, the method further includes:

[0055] Compensating the uplink signal based on the uplink timing offset estimate and / or the uplink frequency offset estimate;

[0056] Sending the compensated uplink signal to the non-terrestrial network node so that the non-terrestrial network node demodulates the compensated uplink signal.

[0057] In a second aspect of the embodiments of the present application, an estimation method for uplink timing offset and / or frequency offset, which is applied to a non-terrestrial network node, includes:

[0058] Sending a Chirp signal to the terminal;

[0059] So that the terminal determines a downlink timing offset estimate and a downlink frequency offset estimate of the downlink between the non-terrestrial network node and the terminal based on the Chirp signal, and determines the uplink timing offset estimate according to the corresponding relationship between the downlink timing offset estimate and the uplink timing offset estimate of the uplink between the non-terrestrial network node and the terminal, and / or determines the uplink frequency offset estimate according to the corresponding relationship between the downlink frequency offset estimate and the uplink frequency offset estimate of the uplink.

[0060] In a third aspect of the embodiments of the present application, an estimation device for uplink timing offset and / or frequency offset, which is applied to a terminal, includes:

[0061] A receiving module, configured to receive a Chirp signal sent by a non-terrestrial network node;

[0062] A determining module, configured to determine a downlink time offset estimation value and a downlink frequency offset estimation value of a downlink between the non-terrestrial network node and the terminal based on the Chirp signal received by the receiving module;

[0063] The determining module is further configured to determine the uplink time offset estimation value according to a corresponding relationship between the downlink time offset estimation value and an uplink time offset estimation value of an uplink between the non-terrestrial network node and the terminal, and / or determine the uplink frequency offset estimation value according to a corresponding relationship between the downlink frequency offset estimation value and an uplink frequency offset estimation value of the uplink.

[0064] Optionally, the receiving module is specifically configured to:

[0065] Receive the Chirp signal broadcast by the non-terrestrial network node through a frequency correction channel.

[0066] Optionally, the determining module is further configured to:

[0067] Obtain a preset frequency sweep range and processing gain;

[0068] Determine a pulse width of the Chirp signal based on the frequency sweep range and the processing gain;

[0069] Determine a frequency modulation slope of the Chirp signal according to the processing gain and the pulse width.

[0070] Optionally, the determining module is specifically configured to:

[0071] Use a ratio of the processing gain to the frequency sweep range as the pulse width of the Chirp signal;

[0072] The determining module is specifically configured to:

[0073] Determine a square value of the pulse width, and use a ratio of the processing gain to the square value as the frequency modulation slope of the Chirp signal.

[0074] Optionally, the determining module is specifically configured to:

[0075] Obtain a local frequency sweep signal, and determine a correlation signal between the local frequency sweep signal and the Chirp signal, where the local frequency sweep signal is the same as the Chirp signal when it is sent;

[0076] Determine the peak frequency of the relevant signal, and based on the peak frequency, determine the first time offset estimate value and the first frequency offset estimate value between when the Chirp signal is transmitted and when it is received;

[0077] Based on the first time offset estimate value, determine the downlink time offset estimate value, and based on the first frequency offset estimate value, determine the downlink frequency offset estimate value.

[0078] Optionally, the local frequency sweep signal includes a local up frequency sweep signal and a local down frequency sweep signal; the determining module is specifically configured to:

[0079] Multiply the local up frequency sweep signal by the Chirp signal to obtain a first correlation signal;

[0080] Multiply the local down frequency sweep signal by the Chirp signal to obtain a second correlation signal.

[0081] Optionally, the determining module is specifically configured to:

[0082] Perform a fast Fourier transform on the first correlation signal to obtain the frequency corresponding to the maximum amplitude in the first correlation signal as the first peak frequency;

[0083] Perform a fast Fourier transform on the second correlation signal to obtain the frequency corresponding to the maximum amplitude of the second correlation signal as the second peak frequency.

[0084] Optionally, the first frequency offset estimate value is:

[0085] f d =(f1 + f2) / 2

[0086] where f d is the first frequency offset estimate value, f1 is the first peak frequency, and f2 is the second peak frequency;

[0087] The first time offset estimate value is:

[0088] t d =(f2 - f1) / (2*μ)

[0089] where t d is the first time offset estimate value, and μ is the frequency modulation slope of the Chirp signal.

[0090] Optionally, the receiving module is further configured to, before determining the downlink time offset estimate value based on the first time offset estimate value and determining the downlink frequency offset estimate value based on the first frequency offset estimate value, receive a downlink signal sent by the non-terrestrial network node to the terminal and obtain a downlink pilot sequence included in the downlink signal;

[0091] The determining module is further configured to determine a second time offset estimation value and a second frequency offset estimation value between when the downlink signal is transmitted and when it is received according to the downlink pilot sequence;

[0092] Specifically, the determining module is configured to:

[0093] Determine the downlink time offset estimation value based on the first time offset estimation value and the second time offset estimation value;

[0094] Determine the downlink frequency offset estimation value based on the first frequency offset estimation value and the second frequency offset estimation value.

[0095] Optionally, specifically, the determining module is configured to:

[0096] Obtain a local pilot sequence, where the local pilot sequence is the same as the downlink pilot sequence when it is transmitted;

[0097] Multiply the downlink pilot sequence and the local pilot sequence to obtain a pilot correlation signal, and determine the autocorrelation peak frequency of the pilot correlation signal;

[0098] Determine the second time offset estimation value and the second frequency offset estimation value according to the autocorrelation peak frequency.

[0099] Optionally, specifically, the determining module is configured to:

[0100] Use the sum of the first time offset estimation value and the second time offset estimation value as the downlink time offset estimation value;

[0101] Specifically, the determining module is configured to:

[0102] Use the sum of the first frequency offset estimation value and the second frequency offset estimation value as the downlink frequency offset estimation value.

[0103] Optionally, specifically, the determining module is configured to:

[0104] Use the product of the downlink time offset estimation value and 2 as the uplink time offset estimation value;

[0105] Specifically, the determining module is configured to:

[0106] Use the downlink frequency offset estimation value as the uplink frequency offset estimation value.

[0107] Optionally, the device further includes:

[0108] A compensation module, configured to, after determining the uplink frequency offset estimation value according to the corresponding relationship between the downlink frequency offset estimation value and the uplink frequency offset estimation value of the uplink, compensate the uplink signal based on the uplink timing offset estimation value and / or the uplink frequency offset estimation value;

[0109] A sending module, configured to send the compensated uplink signal to the non-terrestrial network node, so that the non-terrestrial network node demodulates the compensated uplink signal.

[0110] In a fourth aspect of the embodiments of the present application, there is provided an apparatus for estimating uplink timing offset and / or frequency offset, which is applied to a non-terrestrial network node. The apparatus includes:

[0111] A sending module, configured to send a Chirp signal to a terminal, so that the terminal determines a downlink timing offset estimation value and a downlink frequency offset estimation value of a downlink between the non-terrestrial network node and the terminal based on the Chirp signal, and determine the uplink timing offset estimation value according to the corresponding relationship between the downlink timing offset estimation value and the uplink timing offset estimation value of the uplink between the non-terrestrial network node and the terminal, and / or determine the uplink frequency offset estimation value according to the corresponding relationship between the downlink frequency offset estimation value and the uplink frequency offset estimation value of the uplink.

[0112] In a fifth aspect of the embodiments of the present application, there is provided an electronic device, including a processor, a communication interface, a memory, and a communication bus. Among them, the processor, the communication interface, and the memory complete communication with each other through the communication bus;

[0113] The memory is used to store a computer program;

[0114] The processor is configured to, when executing the program stored in the memory, implement the steps of the method for estimating uplink timing offset and / or frequency offset according to any one of the first aspect or the second aspect.

[0115] In a sixth aspect of the embodiments of the present application, there is provided a computer-readable storage medium, in which a computer program is stored. When the computer program is executed by a processor, the steps of the method for estimating uplink timing offset and / or frequency offset according to any one of the first aspect or the second aspect are implemented.

[0116] In a seventh aspect of the embodiments of the present application, there is provided a computer program product containing instructions. When it runs on a computer, it causes the computer to execute the method for estimating uplink timing offset and / or frequency offset according to any one of the above first aspect or the second aspect.

[0117] Advantages of the embodiments of the present application:

[0118] The method, apparatus, electronic device, and medium for estimating uplink time offset and / or frequency offset provided by the embodiments of the present application. A terminal can receive a Chirp signal sent by a non-terrestrial network node, and then determine a downlink time offset estimation value and a downlink frequency offset estimation value of the downlink between the non-terrestrial network node and the terminal according to the Chirp signal, and thereby determine an uplink time offset estimation value and / or an uplink frequency offset estimation value of the uplink between the non-terrestrial network node and the terminal. Since the Chirp signal belongs to large time-bandwidth product signals, which have the characteristics of long propagation distance, strong correlation, and low demodulation threshold, it can be applied to non-terrestrial network communication systems. Therefore, the embodiments of the present application can estimate the uplink time offset estimation value and / or the uplink frequency offset estimation value in a non-terrestrial network communication system.

[0119] Of course, it is not necessary for any product or method implementing the present application to achieve all the above-mentioned advantages simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0120] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application, and those of ordinary skill in the art can also obtain other embodiments based on these drawings.

[0121] Figure 1 It is an exemplary schematic diagram of a non-terrestrial network communication system provided by the embodiments of the present application;

[0122] Figure 2 It is a flowchart of a method for estimating uplink time offset and / or frequency offset provided by the embodiments of the present application;

[0123] Figure 3 It is a flowchart of a method for estimating downlink time offset and frequency offset provided by the embodiments of the present application;

[0124] Figure 4 It is an exemplary schematic diagram of a process for estimating the first time-frequency offset based on a Chirp signal provided by the embodiments of the present application;

[0125] Figure 5 It is a flowchart of a method for determining a second time-frequency offset estimation value provided by the embodiments of the present application;

[0126] Figure 6 It is an exemplary schematic diagram of a process for estimating the second time-frequency offset based on a pilot signal provided by the embodiments of the present application;

[0127] Figure 7An exemplary schematic diagram of signal compensation provided by an embodiment of the present application;

[0128] Figure 8 A flowchart of another method for estimating uplink timing offset and / or frequency offset provided by an embodiment of the present application;

[0129] Figure 9 A schematic structural diagram of an apparatus for estimating uplink timing offset and / or frequency offset provided by an embodiment of the present application;

[0130] Figure 10 A schematic structural diagram of an electronic device provided by an embodiment of the present application. Detailed implementation manners

[0131] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art based on the present application belong to the scope of protection of the present application.

[0132] Refer to Figure 1 , the non-terrestrial network communication system involved in the embodiments of the present application includes: a terminal 101, a non-terrestrial network node 102, and a gateway station 103. Among them, the gateway station 103 and the non-terrestrial network node 102 are connected through a feeder link, and the non-terrestrial network node 102 and the terminal 101 are connected through a service link, and the service link is also called a user link. The terminal 101 can be called a user equipment (UE). For example, the terminal can be a device such as a mobile phone, a computer, or a wearable watch that has the ability to communicate with the non-terrestrial network node 102. The non-terrestrial network node 102 can be an aircraft such as a satellite or a drone. For example, the non-terrestrial network node 102 can be a low-earth orbit satellite.

[0133] Figure 1 The horizontal lines below the terminal 101 and the gateway station 103 in Figure 1 represent the ground. The area between the dotted lines below the non-terrestrial network node 102 represents the beam coverage area, and the cell reference point is the central reference point of the cell covered by the beam of the non-terrestrial network node 102. It can be seen that

[0134] The non-terrestrial network node 102 can be directly connected to the gateway station 103 through a feeder link. Alternatively, the non-terrestrial network node 102 can be connected to other non-terrestrial network nodes through an inter-non-terrestrial network node link, and then indirectly connected to the gateway station 103 through the feeder link between the other non-terrestrial network node and the gateway station 103. Among them, taking the non-terrestrial network node 102 as a satellite, the inter-non-terrestrial network node link is an Inter-Satellite Link (ISL).

[0135] Since frequency synchronization and timing synchronization between the non-terrestrial network node and the terminal are prerequisites for the terminal to access the network, in order to estimate the time offset and / or frequency offset of the uplink between the non-terrestrial network node and the terminal, the embodiments of the present application provide a method for estimating the uplink time offset and / or frequency offset, which is applied to Figure 1 the terminal in Figure 2 As shown in

[0136] S201: Receive the Chirp signal sent by the non-terrestrial network node.

[0137] In the embodiments of the present application, the non-terrestrial network can periodically broadcast the Chirp signal through a physical Frequency Correction Channel (FCCH), and the periodically broadcast Chirp signal can be pre-configured artificially. Therefore, when the terminal is within the beam coverage range of the non-terrestrial network node, it can receive the Chirp signal broadcast by the non-terrestrial network node through the frequency correction channel. Among them, the FCCH is modulated by the Chirp signal, so as to obtain processing gain while enabling the terminal to estimate the time-frequency deviation of the uplink between the non-terrestrial network node and the terminal based on the Chirp signal.

[0138] Among them, the Chirp signal is a coded pulse signal, which can also be called a chirp signal. The Chirp signal is generally applied to narrowband communication systems, and its frequency has a linear relationship with time, that is, the frequency increases or decreases with time.

[0139] On the other hand, the Chirp signal belongs to large time-bandwidth product signals, that is, signals whose product of time width and bandwidth is much greater than 1, and has characteristics such as long propagation distance, strong correlation, and low demodulation threshold.

[0140] S202: Based on the Chirp signal, determine the downlink time offset estimation value and downlink frequency offset estimation value of the downlink between the non-terrestrial network node and the terminal.

[0141] S203. Determine the uplink time offset estimation value according to the correspondence between the downlink time offset estimation value and the uplink time offset estimation value of the uplink between the non-terrestrial network node and the terminal, and / or determine the uplink frequency offset estimation value according to the correspondence between the downlink frequency offset estimation value and the uplink frequency offset estimation value of the uplink.

[0142] Among them, the correspondence between the downlink time offset estimation value and the uplink time offset estimation value, and the correspondence between the downlink frequency offset estimation value and the uplink frequency offset estimation value can be preset.

[0143] In the uplink time offset and / or frequency offset estimation method provided by the embodiments of the present application, the terminal can receive the Chirp signal sent by the non-terrestrial network node, and then determine the downlink time offset estimation value and the downlink frequency offset estimation value of the downlink between the non-terrestrial network node and the terminal according to the Chirp signal, and determine the uplink time offset estimation value and / or the uplink frequency offset estimation value of the uplink between the non-terrestrial network node and the terminal based on this. Since the Chirp signal belongs to a large time-bandwidth product signal and has the characteristics of long propagation distance, strong correlation and low demodulation threshold, it can be applied to the non-terrestrial network communication system. Therefore, the embodiments of the present application can estimate the uplink time offset estimation value and / or the uplink frequency offset estimation value of the uplink in the non-terrestrial network communication system.

[0144] In the embodiments of the present application, the form of the Chirp signal is generally expressed as:

[0145]

[0146] Among them, s(t) is the Chirp signal, t is the time variable, the unit of t is second (s), p(t) is the unit rectangular pulse, |·| represents the absolute value, cos represents the cosine function, μ is the frequency modulation slope, the unit is Hz / s, and T is the pulse width of the unit rectangular pulse.

[0147] In the Chirp signal shown in the above formula (1), μ and T are two parameters that need to be set. The frequency modulation slope μ and the pulse width T of the Chirp signal can be determined through the following steps:

[0148] Step 1. Obtain the preset frequency sweep range and processing gain.

[0149] Since represents the instantaneous frequency of the Chirp signal, the frequency sweep range of s(t) is (-μT / 2, μT / 2), the signal bandwidth is μT, and the duration of s(t) is T. Perform matched correlation processing on the Chirp signal to obtain a demodulation processing gain of μT*T.

[0150] The μ and T of the Chirp signal are affected by factors such as the frequency accuracy and Doppler frequency shift of the non-terrestrial network communication system. In the non-terrestrial network communication system, when the communication frequency between the non-terrestrial network node and the terminal is small, a large Doppler frequency shift is generated; when the terminal moves at a high speed, a large Doppler frequency shift is generated. In order to enable the non-terrestrial network communication system to have a large processing gain, the set processing gain is X decibels (dB), that is, 10lgX’, where lg is the logarithm with base 10. In order to enable the frequency change of the Chirp signal to cover the initial maximum frequency difference of the non-terrestrial network communication system, the preset frequency sweep range of the Chirp signal is Y. Thus, formula (2) is obtained:

[0151]

[0152] Step 2: Based on the frequency sweep range and the processing gain, determine the pulse width of the Chirp signal, and based on the processing gain and the pulse width, determine the frequency modulation slope of the Chirp signal.

[0153] The ratio of the processing gain to the frequency sweep range can be used as the pulse width of the Chirp signal, and the square value of the determined pulse width, and the ratio of the processing gain to the square value can be used as the frequency modulation slope of the Chirp signal.

[0154] That is, T = X’ / Y can be solved through formula (2). In practical applications, in order to improve the calculation efficiency, T can also be normalized. The set channel symbol rate = Z kilohertz (kHz) can be obtained, then the symbol period T s = 1 / 1000Z, according to the respective numerical sizes of T and T s , T = a*T s . Therefore, it is obtained that

[0155] The Chirp signal generated based on the obtained T and μ can not only cover the initial maximum frequency difference of the non-terrestrial network communication system in terms of frequency change range, but also has a large processing gain, and can also meet the requirements of the non-terrestrial network communication system for timing accuracy.

[0156] After obtaining T and μ, in the above S201, the non-terrestrial network node can generate and send a Chirp signal according to T and μ.

[0157] In the embodiment of the present application, referring to Figure 3 , the method for determining the downlink time offset estimation value and the downlink frequency offset estimation value of the downlink between the non-terrestrial network node and the terminal based on the Chirp signal in the above S202 includes the following steps:

[0158] S301. Obtain a local frequency-sweeping signal, and determine the correlation signal between the local frequency-sweeping signal and the Chirp signal.

[0159] Among them, the local frequency-sweeping signal can be pre-configured in the terminal artificially, and the local frequency-sweeping signal is the same as the Chirp signal when it is sent.

[0160] The local frequency-sweeping signal and the Chirp signal can be multiplied to obtain the correlation signal.

[0161] S302. Determine the peak frequency of the correlation signal, and based on the peak frequency, determine the first time offset estimation value and the first frequency offset estimation value between the Chirp signal when it is sent and when it is received.

[0162] Since the local frequency-sweeping signal is the same as the Chirp signal when it is sent, the peak frequency of the correlation signal between the Chirp signal and the local frequency-sweeping signal is the carrier frequency component in the Chirp signal, so it can be used to estimate the downlink frequency offset estimation value of the downlink between the non-terrestrial network node and the terminal.

[0163] Moreover, since the local frequency-sweeping signal is the same as the Chirp signal when it is sent, when the local frequency-sweeping signal is delayed by a certain time relative to the Chirp signal, the delayed signal component has the same phase as the carrier of the Chirp signal, thus generating a correlation peak. Therefore, the peak frequency of the correlation peak can reflect the time delay of the Chirp signal relative to the local frequency-sweeping signal, so it can be used to estimate the downlink time offset estimation value of the downlink.

[0164] S303. Based on the first time offset estimation value, determine the downlink time offset estimation value, and based on the first frequency offset estimation value, determine the downlink frequency offset estimation value.

[0165] Since the first time offset estimation value is obtained based on the Chirp signal broadcast by the non-terrestrial network node, it can reflect the time offset of the downlink between the non-terrestrial network node and the terminal, so the first time offset estimation value can be used as the downlink time offset estimation value. Similarly, the first frequency offset estimation value can be used as the downlink frequency offset estimation value.

[0166] Alternatively, the downlink time offset estimation value and the downlink frequency offset estimation value can also be determined by the method provided below.

[0167] Through the above method, the terminal can receive the Chirp signal broadcast by the non-terrestrial network node, determine the peak frequency of the correlation signal between the Chirp signal and the local frequency sweep signal. Since the local frequency sweep signal is the same as the Chirp signal when it is sent, the peak frequency of the correlation signal between the Chirp signal and the local frequency sweep signal is the carrier frequency component in the Chirp signal, and it can reflect the time delay of the Chirp signal relative to the local frequency sweep signal. Therefore, the embodiment of the present application can estimate the downlink time offset estimate value and the downlink frequency offset estimate value of the downlink based on the peak frequency of the correlation signal. Since the Chirp signal belongs to a large time-bandwidth product signal and has the characteristics of long propagation distance, strong correlation and low demodulation threshold, it can be applied to the non-terrestrial network communication system. Therefore, the embodiment of the present application can realize estimating the downlink time offset estimate value and the downlink frequency offset estimate value in the non-terrestrial network communication system.

[0168] According to Euler's formula, formula (1) can also be expressed as:

[0169]

[0170] where j is the imaginary unit and e is the natural constant.

[0171] It can be seen from formula (3) that the Chirp signal can be divided into two parts. The first part is the up frequency sweep, and the frequency of the up frequency sweep increases linearly with time. The second part is the down frequency sweep, and the frequency of the down frequency sweep decreases linearly with time. Assume that the Chirp signal received by the terminal is expressed as r(t) = ru(t) + rd(t), where ru(t) is the up frequency sweep and rd(t) is the down frequency sweep.

[0172] Without considering noise, ru(t) and rd(t) are:

[0173]

[0174]

[0175] where f d is the frequency difference between the Chirp signal when it is sent and when it is received, that is, the first time offset estimate value, and t d is the time deviation between the local frequency sweep signal and the received Chirp signal, that is, the first time offset estimate value.

[0176] In the embodiment of the present application, the local frequency sweep signal in S301 above includes the local up frequency sweep signal and the local down frequency sweep signal, and the local up frequency sweep signal is the same as the up frequency sweep signal included in the Chirp signal when it is sent, and the local down frequency sweep signal is the same as the down frequency sweep signal included in the Chirp signal when it is sent.

[0177] The method of determining the correlation signals of the local sweep signal and the Chirp signal in S301 above can be implemented as: multiplying the local up-sweep signal by the Chirp signal to obtain a first correlation signal, and multiplying the local down-sweep signal by the Chirp signal to obtain a second correlation signal.

[0178] After that, the method of determining the peak frequency in S302 above can be implemented as: performing a fast Fourier transform on the first correlation signal to obtain the frequency corresponding to the largest amplitude in the first correlation signal as the first peak frequency, and performing a fast Fourier transform on the second correlation signal to obtain the frequency corresponding to the largest amplitude of the second correlation signal as the second peak frequency.

[0179] Multiplying the local up-sweep and the received Chirp signal, the obtained first correlation signal is a binomial. Among them, in the binomial of the first correlation signal, the term with the same frequency change rate and the same direction as the received Chirp signal is a sweep signal with a doubled frequency change rate; for the term with the same frequency change rate as the received Chirp signal but the opposite direction, since the sweep parts cancel each other out, what remains is a single-frequency signal generated by f d and t d . Performing an FFT on the first correlation signal, thereby transforming the first correlation signal from the time domain to the frequency domain, and calculating the amplitude spectrum of the first correlation signal transformed to the frequency domain, taking the frequency component with the largest amplitude as the first peak frequency. That is, after performing an FFT on the first correlation signal, the power of the first correlation signal is concentrated on a single frequency point, and this frequency point is the first peak frequency.

[0180] The method of obtaining the second peak frequency is the same as the method of obtaining the first peak frequency, and reference can be made to the above description, which will not be elaborated here.

[0181] Combined with the above formula (4), the first peak frequency f1 = f d - μt d . Combined with the above formula (5), the second peak frequency f2 = f d + μt d .

[0182] Therefore, the first frequency offset estimation value determined in S302 above is:

[0183] f d = (f1 + f2) / 2 (6)

[0184] Wherein, f d is the first frequency offset estimation value, f1 is the first peak frequency, and f2 is the second peak frequency.

[0185] The first time offset estimation value determined in S302 above is:

[0186] td =(f2 - f1) / (2*μ) (7)

[0187] where t d is the first time offset estimation value, μ is a preset frequency modulation slope, and * represents multiplication.

[0188] Compared with the method of performing time-frequency offset estimation on the pilot signal included in the downlink signal transmitted by the non-terrestrial network node, due to the weak correlation effect of the pilot signal, it is easily damaged and easily affected by the channel transmission conditions, making this method have limitations.

[0189] In the embodiment of the present application, time-frequency offset estimation is performed based on the Chirp signal transmitted by the non-terrestrial network node. Due to the characteristics of the Chirp signal having strong correlation and low demodulation threshold, based on the Chirp signal, the accuracy of the estimated time offset and frequency offset can be improved. Therefore, even in a transmission environment with a low signal-to-noise ratio, the embodiment of the present application can ensure a high estimation accuracy, improving the demodulation performance and signal acquisition performance.

[0190] Through the above method, the embodiment of the present application can pre-estimate the frequency offset and time offset of the downlink, providing a basis for subsequent demodulation of the downlink signal.

[0191] Figure 4 This is the process of determining the first time offset estimation value and the first frequency offset estimation value based on the Chirp signal in the embodiment of the present application. Refer to Figure 4 . Multiply the local up-swept frequency signal by the Chirp signal to obtain the first correlation signal, perform a fast Fourier transform on the first correlation signal, and obtain the frequency corresponding to the maximum amplitude in the first correlation signal as the first peak frequency. Multiply the local down-swept frequency signal by the Chirp signal to obtain the second correlation signal, perform a fast Fourier transform on the second correlation signal, and obtain the frequency corresponding to the maximum amplitude of the second correlation signal as the second peak frequency. Then, based on the first peak frequency and the second peak frequency, determine the first frequency offset estimation value and the first time offset estimation value.

[0192] In the embodiment of the present application, on the basis of roughly estimating the first time offset estimation value and the first frequency offset estimation value based on the Chirp signal in the process shown above Figure 3 , the embodiment of the present application can also combine the pilot signal in the downlink signal transmitted by the non-terrestrial network node to perform more accurate time-frequency offset estimation. Therefore, refer to Figure 5 . Before the method of determining the downlink time offset estimation value and the downlink frequency offset estimation value of the downlink between the non-terrestrial network node and the terminal in S303 above, the terminal can also perform the following steps:

[0193] S501. Receive the downlink signal sent by the non-terrestrial network node to the terminal, and obtain the downlink pilot sequence included in the downlink signal.

[0194] The downlink pilot sequence sent by the non-terrestrial network node is a known signal and can be artificially configured in the non-terrestrial network node.

[0195] The embodiments of the present application can be applied to the process of the terminal accessing the non-terrestrial network node. The downlink signal in S501 can be the signal sent by the non-terrestrial network node to the terminal each time during the random access process.

[0196] For example, during the random access process between the terminal and the non-terrestrial network node, the terminal sends a random access request to the non-terrestrial network node. After that, the non-terrestrial network node sends a random access response to the terminal, and this random access response can be used as the downlink signal in S501. Then the terminal estimates the time offset and frequency offset of the downlink based on Figure 5 the method shown, and demodulates the downlink signal.

[0197] After that, the terminal sends a connection establishment request message to the non-terrestrial network node, and the non-terrestrial network node sends a connection establishment success message (set up) to the terminal. The connection establishment success message can be used as the downlink signal in S501. Then the terminal estimates the time offset and frequency offset of the downlink based on Figure 5 the method shown, and demodulates the downlink signal.

[0198] S502. Determine a second time offset estimation value and a second frequency offset estimation value between when the downlink signal is sent and when it is received according to the downlink pilot sequence.

[0199] A local pilot sequence can be obtained. The local pilot sequence is a known signal and can be artificially configured in the non-terrestrial network node, and the local pilot sequence is the same as the downlink pilot sequence when it is sent. Then multiply the downlink pilot sequence and the local pilot sequence to obtain a pilot correlation signal, and determine the autocorrelation peak frequency of the pilot correlation signal. Among them, a sliding window with a preset length can be set, and the downlink pilot sequence and the local pilot sequence are intercepted through the sliding window. Multiply the downlink pilot sequence and the local pilot sequence within the sliding window to obtain a pilot correlation signal, and perform FFT on the pilot correlation signal, so as to convert the pilot correlation signal within the window from the time domain to the frequency domain. Then move the position of the sliding window, and return to the step of intercepting the downlink pilot sequence and the local pilot sequence through the sliding window.

[0200] Among them, performing a fast Fourier transform on the pilot correlation signal can be expressed as:

[0201]

[0202] Among them, is the signal after the fast Fourier transform of the pilot-related signal within the window, which can represent the amplitude of the transformed signal, n represents the position of the window in the pilot-related signal. K is the length of the local pilot sequence, that is, the length of the local pilot sequence, Y k represents the local pilot sequence, M k represents the downlink pilot sequence, and FFT represents the fast Fourier transform.

[0203] Then, perform autocorrelation calculation on the pilot-related signal in the frequency domain to obtain the autocorrelation sequence within the window, obtain the maximum frequency value from each autocorrelation sequence, obtain the autocorrelation peak frequency of the pilot-related signal, and the sliding window position corresponding to the autocorrelation peak frequency.

[0204] Since the local pilot sequence is the same as the downlink pilot sequence when it is transmitted, the autocorrelation peak frequencies of the downlink pilot sequence and the local pilot sequence are the carrier frequency components in the downlink pilot sequence, so they can be used to estimate the downlink frequency offset estimation value of the downlink link.

[0205] Moreover, since the local pilot sequence is the same as the downlink pilot sequence when it is transmitted, when the local pilot sequence is delayed by a certain time relative to the downlink pilot sequence, the delayed signal component has the same phase as the carrier of the downlink pilot sequence, thus generating an autocorrelation peak. Therefore, the autocorrelation peak frequency of the autocorrelation peak can reflect the time delay of the downlink pilot sequence relative to the local pilot sequence, so it can be used to estimate the downlink time offset estimation value of the downlink link.

[0206] Then, according to the autocorrelation peak frequency, determine the second time offset estimation value and the second frequency offset estimation value. That is, based on formula (8), when the window position n = η, obtain the position n1 of the autocorrelation peak frequency, and the autocorrelation peak frequency is included within the window, and the second frequency offset estimation value is obtained as:

[0207]

[0208] where, is the second frequency offset estimation value.

[0209] Based on the position of the autocorrelation peak, the second time offset estimation value can be obtained:

[0210] t est =(n1 - n toa ) / f s (10)

[0211] where, t est is the second time offset estimation value, n toa is the theoretical position of the frame header in the downlink pilot sequence, n toa is set based on the frame structure of the downlink pilot sequence, n toa can be pre-configured in the terminal, fs is the preset signal sampling rate for the downlink pilot sequence.

[0212] Based on this, the method for the above S303 to determine the downlink time offset estimation value and downlink frequency offset estimation value of the downlink between the non-terrestrial network node and the terminal includes the following steps:

[0213] Step 1: Determine the downlink time offset estimation value based on the first time offset estimation value and the second time offset estimation value.

[0214] The sum of the first time offset estimation value and the second time offset estimation value can be used as the downlink time offset estimation value through formula (11):

[0215] t DL = t d + t est (11)

[0216] where t DL is the downlink time offset estimation value, t d is the first time offset estimation value, t est is the second time offset estimation value.

[0217] Step 2: Determine the downlink frequency offset estimation value based on the first frequency offset estimation value and the second frequency offset estimation value.

[0218] The sum of the first frequency offset estimation value and the second frequency offset estimation value can be used as the downlink frequency offset estimation value through formula (12):

[0219]

[0220] where f DL is the downlink frequency offset estimation value, f d is the first frequency offset estimation value, is the second frequency offset estimation value.

[0221] Based on estimating the time offset and frequency offset of the downlink based on the Chirp signal, the embodiment of the present application can also complete the second time-frequency offset estimation of the downlink based on the pilot signal included in the downlink signal sent by the non-terrestrial network node and using the correlation characteristics between the local pilot sequence and the downlink pilot sequence. Thus, a more accurate downlink frequency offset estimation value of the downlink can be determined based on the frequency offsets obtained by these two methods, and a more accurate downlink time offset estimation value of the downlink can be determined based on the time offsets obtained by these two methods.

[0222] Figure 6 is the process of time-frequency offset estimation based on the downlink pilot sequence. See Figure 6, the terminal performs sliding correlation on the downlink pilot sequence and the local pilot sequence, that is, multiplies the downlink pilot sequence and the local pilot sequence within the sliding window to obtain a pilot correlation signal. Then, perform FFT on the pilot correlation signal to obtain the autocorrelation peak frequency of the pilot correlation signal. Then, determine the second time offset estimate value and the second frequency offset estimate value according to the autocorrelation peak frequency.

[0223] In the embodiment of the present application, after the terminal estimates the time and frequency offsets of the downlink, it can also compensate the downlink signal received in S501 based on the estimated downlink frequency offset estimate value and downlink time offset estimate value, so as to demodulate the downlink signal more accurately and improve the demodulation success rate.

[0224] In a traditional non-terrestrial network communication system, non-terrestrial network nodes usually act as transparent forwarding carriers, that is, non-terrestrial network nodes do not perform modulation and demodulation processing on signals. Therefore, the uplink signal sent by the terminal needs to be sent to the gateway station through non-terrestrial network nodes. That is, the uplink includes the link from the terminal to the gateway station. Then, the gateway station demodulates and processes the uplink signal. In this case, in order to perform time and frequency offset compensation on the uplink signal, the terminal needs to use the ephemeris information of non-terrestrial network nodes to estimate the time offset and frequency offset of the uplink, and pre-compensate the uplink signal based on this. Then, send the uplink signal to non-terrestrial network nodes, and the non-terrestrial network nodes transparently forward the uplink signal to the gateway station. After receiving the uplink signal, the gateway station estimates the time offset and frequency offset of the uplink based on its own position and the ephemeris information of non-terrestrial network nodes, and then compensates and demodulates the uplink signal based on this.

[0225] In this method, since the uplink includes the link from the terminal to the gateway station, the uplink is relatively long, and the transmission time of the uplink signal is relatively long, increasing the delay of transmitting the uplink signal in the non-terrestrial network communication system.

[0226] In the embodiment of the present application, due to the development of the manufacturing technology of non-terrestrial network nodes, the resources of non-terrestrial network nodes have been effectively improved. Therefore, it becomes feasible to perform demodulation processing on the uplink signal on non-terrestrial network nodes. Therefore, in the embodiment of the present application, the uplink signal sent by the terminal can be demodulated on the non-terrestrial network node side. Only the associated measurement and control information can be transmitted between the non-terrestrial network node and the gateway station, reducing the processing complexity of the non-terrestrial network communication system, so that the uplink can only include the transmission link from the terminal to the non-terrestrial network node. Therefore, the transmission delay of the uplink signal is reduced, meeting the real-time demodulation requirements in the non-terrestrial network communication system.

[0227] In addition, it is generally difficult for a terminal to obtain real-time ephemeris information of non-terrestrial network nodes. If the terminal does not have real-time ephemeris information at present, it is impossible to perform time-frequency offset estimation and pre-compensation on the uplink signal. Therefore, when the terminal does not have real-time ephemeris information, time-frequency offset estimation for the uplink has broad practical significance.

[0228] In an embodiment of the present application, the method for determining the uplink time offset estimation value according to the correspondence between the downlink time offset estimation value and the uplink time offset estimation value of the uplink between the non-terrestrial network node and the terminal in S203 can be implemented as: multiplying the downlink time offset estimation value by 2 as the uplink time offset estimation value.

[0229] That is, the uplink time offset estimation value of the uplink is:

[0230] t UL = 2t DL (13)

[0231] Wherein, t UL is the uplink time offset estimation value, and t DL is the downlink time offset estimation value.

[0232] The method for determining the uplink frequency offset estimation value according to the correspondence between the downlink frequency offset estimation value and the uplink frequency offset estimation value of the uplink in S203 can be implemented as: using the downlink frequency offset estimation value as the uplink frequency offset estimation value of the uplink.

[0233] That is. The uplink frequency offset estimation value of the uplink is:

[0234] f UL = f DL (14)

[0235] Wherein, f UL is the uplink frequency offset estimation value, and f DL is the downlink frequency offset estimation value.

[0236] Through the above method, the embodiment of the present application can determine the time-frequency offset of the uplink between the terminal and the non-terrestrial network node based on the time-frequency offset estimated by the downlink. It can be seen that when estimating the time-frequency offset of the uplink in the embodiment of the present application, it is not necessary to rely on the real-time ephemeris information of the non-terrestrial network node. Therefore, it can accurately estimate the time-frequency offset of the uplink and compensate the uplink signal when the terminal does not have real-time ephemeris information, meet the demodulation requirements of multi-carrier communication under the large Doppler carrier frequency offset in the non-terrestrial network communication system, improve the probability of successful demodulation of the uplink signal received by the non-terrestrial network node, and also reduce the computational complexity. The time-frequency offset estimation method for the uplink provided by the embodiment of the present application can improve the estimation accuracy and reduce the computational complexity in a high-dynamic and low-signal-to-noise ratio environment, and thus is easy to implement in engineering.

[0237] After determining the uplink time-frequency offset estimation value in S203 above, the terminal may further: Based on the uplink time offset estimation value and / or the uplink frequency offset estimation value, compensate the uplink signal, and send the compensated uplink signal to the non-terrestrial network node, so that the non-terrestrial network node demodulates the compensated uplink signal.

[0238] When compensating the uplink signal, the uplink frequency offset estimation value may be superimposed on the basis of the frequency of the generated uplink signal, and the time offset estimation value may be superimposed on the generated uplink signal in the time domain to obtain the compensated uplink signal.

[0239] The embodiments of the present application may be applied to the process of the terminal accessing the non-terrestrial network node. Therefore, the uplink signal sent by the terminal may be the signal sent by the terminal to the non-terrestrial network node each time during the random access process. For example, during the random access process between the terminal and the non-terrestrial network node, the terminal sends a random access request to the non-terrestrial network node, and this request may be an uplink signal. After that, the terminal receives a random access response sent by the non-terrestrial network node. Then, the terminal sends a connection establishment request message to the non-terrestrial network node, and this message may be an uplink signal. After that, the non-terrestrial network node sends a connection establishment success message to the terminal.

[0240] See Figure 7 , the following gives an example of the process of the terminal compensating the downlink signal using the downlink time offset estimation value and compensating the uplink signal using the uplink time offset estimation value:

[0241] Figure 7 The first row of squares in represents the downlink signal sent by the non-terrestrial network node, and each square represents one frame of the downlink signal. The third row of squares represents the downlink signal received by the terminal. Using the second frame of the downlink signal as the reference frame, that is, Figure 7 the hatched square in, compared with the downlink signal sent by the non-terrestrial network node and the downlink signal received by the terminal, there is an offset of t DL in the time domain, that is, after the non-terrestrial network node sends the downlink signal, after a time of t DL , the terminal receives the downlink signal. Figure 7 The number of frames included in the downlink signal in is only an example and is not used to limit the actual number of frames included in the downlink signal.

[0242] Figure 7 The fourth row of squares in represents the uplink signal that the terminal originally needs to send. For simplicity of description, Figure 7 only one frame included in the uplink signal is shown in. In fact, the uplink signal may include one frame or multiple frames. Before sending the uplink signal, the terminal may compensate the uplink signal according to the uplink time offset estimation value, that is, 2t DL , and the compensated uplink signal is Figure 7The square in the fifth line of []. It can be seen that compared with the uplink signal before compensation, there is an offset of 2t in the time domain for the compensated uplink signal, that is, the terminal can send the uplink signal 2t earlier in the time domain. DL to the non-terrestrial network node. Due to the time offset of t between the link of the non-terrestrial network node and the terminal, the uplink signal received by the non-terrestrial network node is DL the square in the second line of []. It can be seen that compared with the uplink signal sent by the terminal, there is an offset of t in the time domain for the uplink signal received by the non-terrestrial network node. DL Figure 7 DL of offset.

[0243] Based on the same inventive concept, an embodiment of the present application further provides a method for estimating uplink time offset and / or frequency offset, which is applied to a non-terrestrial network node. As shown in Figure 8 , the method includes the following steps:

[0244] S801. Send a Chirp signal to the terminal.

[0245] S802. So that the terminal determines a downlink time offset estimation value and a downlink frequency offset estimation value of the downlink between the non-terrestrial network node and the terminal based on the Chirp signal, and determines an uplink time offset estimation value according to the corresponding relationship between the downlink time offset estimation value and the uplink time offset estimation value of the uplink between the non-terrestrial network node and the terminal, and / or determines an uplink frequency offset estimation value according to the corresponding relationship between the downlink frequency offset estimation value and the uplink frequency offset estimation value of the uplink.

[0246] In the embodiment of the present application, the manner of the non-terrestrial network node sending the Chirp signal, the form of the Chirp signal, and the manner of the terminal estimating the uplink time offset estimation value and / or the uplink frequency offset estimation value based on the Chirp signal can all refer to the above description and will not be elaborated here.

[0247] For the method for estimating uplink time offset and / or frequency offset provided by the embodiment of the present application, after the non-terrestrial network node sends a Chirp signal to the terminal, the terminal can determine a downlink time offset estimation value and a downlink frequency offset estimation value of the downlink between the non-terrestrial network node and the terminal according to the received Chirp signal, and determine an uplink time offset estimation value and / or an uplink frequency offset estimation value of the uplink between the non-terrestrial network node and the terminal based on this. Since the Chirp signal belongs to a large time-bandwidth product signal and has the characteristics of long propagation distance, strong correlation, and low demodulation threshold, it can be applied to the non-terrestrial network communication system. Therefore, the embodiment of the present application can realize estimating the uplink time offset estimation value and / or the uplink frequency offset estimation value of the uplink in the non-terrestrial network communication system.

[0248] ​​Based on the same inventive concept, an embodiment of the present application further provides an apparatus for estimating uplink time offset and / or frequency offset, which is applied to a terminal, such as Figure 9 shown. The apparatus includes: a receiving module 901 and a determining module 902;

[0249] The receiving module 901 is configured to receive a Chirp signal sent by a non-terrestrial network node;

[0250] The determining module 902 is configured to determine a downlink time offset estimation value and a downlink frequency offset estimation value of a downlink between the non-terrestrial network node and the terminal based on the Chirp signal received by the receiving module 901;

[0251] The determining module 902 is further configured to determine an uplink time offset estimation value according to the corresponding relationship between the downlink time offset estimation value and the uplink time offset estimation value of the uplink between the non-terrestrial network node and the terminal, and / or determine an uplink frequency offset estimation value according to the corresponding relationship between the downlink frequency offset estimation value and the uplink frequency offset estimation value of the uplink.

[0252] Optionally, the receiving module 901 is specifically configured to:

[0253] Receive the Chirp signal broadcast by the non-terrestrial network node through the frequency correction channel.

[0254] Optionally, the determining module 902 is further configured to:

[0255] Obtain a preset frequency sweep range and processing gain;

[0256] Determine the pulse width of the Chirp signal based on the frequency sweep range and the processing gain;

[0257] Determine the frequency modulation slope of the Chirp signal according to the processing gain and the pulse width.

[0258] Optionally, the determining module 902 is specifically configured to:

[0259] Take the ratio of the processing gain to the frequency sweep range as the pulse width of the Chirp signal;

[0260] The determining module 902 is specifically configured to:

[0261] Determine the square value of the pulse width, and take the ratio of the processing gain to the square value as the frequency modulation slope of the Chirp signal.

[0262] Optionally, the determining module 902 is specifically configured to:

[0263] Obtain a local frequency sweep signal, and determine a correlation signal between the local frequency sweep signal and the Chirp signal, where the local frequency sweep signal is the same as the Chirp signal when it is sent;

[0264] Determine the peak frequency of the relevant signal, and based on the peak frequency, determine the first time offset estimation value and the first frequency offset estimation value between when the Chirp signal is transmitted and when it is received;

[0265] Based on the first time offset estimation value, determine the downlink time offset estimation value, and based on the first frequency offset estimation value, determine the downlink frequency offset estimation value.

[0266] Optionally, the local frequency sweep signal includes a local up frequency sweep signal and a local down frequency sweep signal; the determination module 902 is specifically configured to:

[0267] Multiply the local up frequency sweep signal by the Chirp signal to obtain a first correlation signal;

[0268] Multiply the local down frequency sweep signal by the Chirp signal to obtain a second correlation signal.

[0269] Optionally, the determination module 902 is specifically configured to:

[0270] Perform a fast Fourier transform on the first correlation signal to obtain the frequency corresponding to the largest amplitude in the first correlation signal as the first peak frequency;

[0271] Perform a fast Fourier transform on the second correlation signal to obtain the frequency corresponding to the largest amplitude of the second correlation signal as the second peak frequency.

[0272] Optionally, the first frequency offset estimation value is:

[0273] f d =(f1 + f2) / 2

[0274] where f d is the first frequency offset estimation value, f1 is the first peak frequency, and f2 is the second peak frequency;

[0275] The first time offset estimation value is:

[0276] t d =(f2 - f1) / (2*μ)

[0277] where t d is the first time offset estimation value, and μ is the frequency modulation slope of the Chirp signal.

[0278] Optionally, the receiving module 901 is further configured to receive a downlink signal sent by a non-terrestrial network node to the terminal and obtain a downlink pilot sequence included in the downlink signal before determining the downlink time offset estimation value based on the first time offset estimation value and determining the downlink frequency offset estimation value based on the first frequency offset estimation value;

[0279] The determination module 902 is further configured to determine a second time offset estimation value and a second frequency offset estimation value between when the downlink signal is transmitted and when it is received according to the downlink pilot sequence;

[0280] The determination module 902 is specifically configured to:

[0281] Determine a downlink time offset estimation value based on the first time offset estimation value and the second time offset estimation value;

[0282] Determine a downlink frequency offset estimation value based on the first frequency offset estimation value and the second frequency offset estimation value.

[0283] Optionally, the determination module 902 is specifically configured to:

[0284] Obtain a local pilot sequence, where the local pilot sequence is the same as the downlink pilot sequence when it is transmitted;

[0285] Multiply the downlink pilot sequence by the local pilot sequence to obtain a pilot correlation signal, and determine the autocorrelation peak frequency of the pilot correlation signal;

[0286] Determine the second time offset estimation value and the second frequency offset estimation value according to the autocorrelation peak frequency.

[0287] Optionally, the determination module 902 is specifically configured to:

[0288] Use the sum of the first time offset estimation value and the second time offset estimation value as the downlink time offset estimation value;

[0289] The determination module 902 is specifically configured to:

[0290] Use the sum of the first frequency offset estimation value and the second frequency offset estimation value as the downlink frequency offset estimation value.

[0291] Optionally, the determination module 902 is specifically configured to:

[0292] Use twice the downlink time offset estimation value as the uplink time offset estimation value;

[0293] The determination module 902 is specifically configured to:

[0294] Use the downlink frequency offset estimation value as the uplink frequency offset estimation value.

[0295] Optionally, the apparatus may further include:

[0296] A compensation module, configured to, after determining the uplink frequency offset estimation value according to the corresponding relationship between the downlink frequency offset estimation value and the uplink frequency offset estimation value of the uplink link, compensate the uplink signal based on the uplink time offset estimation value and / or the uplink frequency offset estimation value;

[0297] A sending module, configured to send a compensated uplink signal to a non-terrestrial network node, so that the non-terrestrial network node demodulates the compensated uplink signal.

[0298] Based on the same inventive concept, an embodiment of the present application further provides an apparatus for estimating uplink time offset and / or frequency offset, which is applied to a non-terrestrial network node. The apparatus may include: a sending module;

[0299] The sending module is configured to send a Chirp signal to a terminal, so that the terminal determines a downlink time offset estimation value and a downlink frequency offset estimation value of a downlink between the non-terrestrial network node and the terminal based on the Chirp signal, and determines an uplink time offset estimation value according to a corresponding relationship between the downlink time offset estimation value and an uplink time offset estimation value of an uplink between the non-terrestrial network node and the terminal, and / or determines an uplink frequency offset estimation value according to a corresponding relationship between the downlink frequency offset estimation value and an uplink frequency offset estimation value of the uplink.

[0300] An embodiment of the present application further provides an electronic device, as Figure 10 shown, including a processor 1001, a communication interface 1002, a memory 1003, and a communication bus 1004. Among them, the processor 1001, the communication interface 1002, and the memory 1003 complete communication with each other through the communication bus 1004.

[0301] The memory 1003 is used to store a computer program;

[0302] When the processor 1001 executes the program stored on the memory 1003, it implements the method steps executed by the terminal or the non-terrestrial network node in the above method embodiment.

[0303] The communication bus mentioned in the above electronic device may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The communication bus can be divided into an address bus, a data bus, a control bus, etc. For the sake of simplicity, only a thick line is shown in the figure, but it does not mean that there is only one bus or one type of bus.

[0304] The communication interface is used for communication between the above electronic device and other devices.

[0305] The memory may include a Random Access Memory (RAM), or may also include a Non-Volatile Memory (NVM), such as at least one disk memory. Optionally, the memory may also be at least one storage device located away from the aforementioned processor.

[0306] The aforementioned processor may be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), etc.; it may also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0307] In another embodiment provided by the present application, there is also provided a computer-readable storage medium, in which a computer program is stored, and when the computer program is executed by a processor, the steps of any of the above-mentioned uplink timing offset and / or frequency offset estimation methods are implemented.

[0308] In another embodiment provided by the present application, there is also provided a computer program product containing instructions, which when running on a computer, causes the computer to execute any of the uplink timing offset and / or frequency offset estimation methods in the above embodiments.

[0309] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access, or a data storage device such as a server or data center that includes one or more integrated available media. The available media can be magnetic media (such as floppy disks, hard disks, magnetic tapes), optical media (such as DVDs), or semiconductor media (such as solid state disks (SSDs)).

[0310] It should be noted that, in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including", or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or device that includes a series of elements not only includes those elements but also includes other elements that are not explicitly listed, or further includes elements that are inherent to such process, method, article, or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article, or device that includes the element.

[0311] Each embodiment in this specification is described in a related manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the device embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and reference can be made to the relevant parts of the method embodiments for the relevant content.

[0312] The above are only the preferred embodiments of the present application and are not intended to limit the protection scope of the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application are all included in the protection scope of the present application.

Claims

1. A method for estimating uplink timing offset and / or frequency offset, characterized in that, Applied to a terminal, the method includes: Receiving a Chirp signal sent by a non-terrestrial network node; Based on the Chirp signal, determining a downlink time offset estimation value and a downlink frequency offset estimation value of a downlink between the non-terrestrial network node and the terminal; Determining the uplink time offset estimation value according to a corresponding relationship between the downlink time offset estimation value and an uplink time offset estimation value of an uplink between the non-terrestrial network node and the terminal, and / or determining the uplink frequency offset estimation value according to a corresponding relationship between the downlink frequency offset estimation value and an uplink frequency offset estimation value of the uplink.

2. The method according to claim 1, wherein The receiving the Chirp signal sent by the non-terrestrial network node includes: Receiving the Chirp signal broadcast by the non-terrestrial network node through a frequency correction channel.

3. The method according to claim 1 or 2, characterized in that, The frequency modulation slope and pulse width of the Chirp signal are determined by the following method: Obtaining a preset frequency sweep range and processing gain; Based on the frequency sweep range and the processing gain, determining the pulse width of the Chirp signal; According to the processing gain and the pulse width, determining the frequency modulation slope of the Chirp signal.

4. The method according to claim 3, wherein The based on the frequency sweep range and the processing gain, determining the pulse width of the Chirp signal includes: Taking the ratio of the processing gain to the frequency sweep range as the pulse width of the Chirp signal; The according to the processing gain and the pulse width, determining the frequency modulation slope of the Chirp signal includes: Determining the square value of the pulse width, and taking the ratio of the processing gain to the square value as the frequency modulation slope of the Chirp signal.

5. The method according to claim 1, characterized in that, The based on the Chirp signal, determining the downlink time offset estimation value and the downlink frequency offset estimation value of the downlink between the non-terrestrial network node and the terminal includes: Obtaining a local frequency sweep signal, and determining a correlation signal between the local frequency sweep signal and the Chirp signal, where the local frequency sweep signal is the same as the Chirp signal when it is sent; Determining a peak frequency of the correlation signal, and based on the peak frequency, determining a first time offset estimation value and a first frequency offset estimation value between when the Chirp signal is sent and when it is received; Based on the first time offset estimation value, determining the downlink time offset estimation value, and based on the first frequency offset estimation value, determining the downlink frequency offset estimation value.

6. The method according to claim 5, characterized in that The local frequency sweep signal includes a local up frequency sweep signal and a local down frequency sweep signal; the determining the correlation signal between the local frequency sweep signal and the Chirp signal includes: Multiplying the local up frequency sweep signal by the Chirp signal to obtain a first correlation signal; Multiplying the local down frequency sweep signal by the Chirp signal to obtain a second correlation signal.

7. The method according to claim 6, wherein The determining the peak frequency of the correlation signal includes: Performing a fast Fourier transform on the first correlation signal to obtain the frequency corresponding to the largest amplitude in the first correlation signal as a first peak frequency; Performing a fast Fourier transform on the second correlation signal to obtain the frequency corresponding to the largest amplitude of the second correlation signal as a second peak frequency.

8. The method according to any one of claims 5 to 7, characterized in that, Before determining the downlink time offset estimate based on the first time offset estimate value and determining the downlink frequency offset estimate based on the first frequency offset estimate value, it includes: Receiving a downlink signal sent by the non-terrestrial network node to the terminal and obtaining a downlink pilot sequence included in the downlink signal; Determining a second time offset estimate value and a second frequency offset estimate value between when the downlink signal is sent and when it is received according to the downlink pilot sequence; The determining the downlink time offset estimate based on the first time offset estimate value and determining the downlink frequency offset estimate based on the first frequency offset estimate value includes: Determining the downlink time offset estimate based on the first time offset estimate value and the second time offset estimate value; Determining the downlink frequency offset estimate based on the first frequency offset estimate value and the second frequency offset estimate value.

9. The method according to claim 8, characterized in that, The determining the second time offset estimate value and the second frequency offset estimate value between when the downlink signal is sent and when it is received according to the downlink pilot sequence includes: Obtaining a local pilot sequence, where the local pilot sequence is the same as the downlink pilot sequence when it is sent; Multiplying the downlink pilot sequence and the local pilot sequence to obtain a pilot correlation signal and determining the autocorrelation peak frequency of the pilot correlation signal; Determining the second time offset estimate value and the second frequency offset estimate value according to the autocorrelation peak frequency.

10. The method according to claim 8, wherein The determining the downlink time offset estimate based on the first time offset estimate value and the second time offset estimate value includes: Taking the sum of the first time offset estimate value and the second time offset estimate value as the downlink time offset estimate value; The determining the downlink frequency offset estimate based on the first frequency offset estimate value and the second frequency offset estimate value includes: Taking the sum of the first frequency offset estimate value and the second frequency offset estimate value as the downlink frequency offset estimate value.

11. The method according to claim 1, wherein After determining the uplink frequency offset estimate according to the correspondence between the downlink frequency offset estimate and the uplink frequency offset estimate of the uplink link, the method further includes: Compensating the uplink signal based on the uplink time offset estimate value and / or the uplink frequency offset estimate value; Sending the compensated uplink signal to the non-terrestrial network node so that the non-terrestrial network node performs demodulation processing on the compensated uplink signal.

12. A method for estimating uplink timing offset and / or frequency offset, characterized in that, Applied to a non-terrestrial network node, the method includes: Sending a Chirp signal to the terminal; So that the terminal determines a downlink time offset estimate value and a downlink frequency offset estimate value of the downlink link between the non-terrestrial network node and the terminal based on the Chirp signal, and determines the uplink time offset estimate value according to the correspondence between the downlink time offset estimate value and the uplink time offset estimate value of the uplink link between the non-terrestrial network node and the terminal, and / or determines the uplink frequency offset estimate value according to the correspondence between the downlink frequency offset estimate value and the uplink frequency offset estimate value of the uplink link.

13. An apparatus for estimating uplink timing offset and / or frequency offset, characterized in that, Applied to a terminal, the device includes: A receiving module, configured to receive a Chirp signal sent by a non-terrestrial network node; A determination module, configured to determine a downlink time offset estimation value and a downlink frequency offset estimation value of a downlink between the non-terrestrial network node and the terminal based on the Chirp signal received by the receiving module; The determination module is further configured to determine the uplink time offset estimation value according to the corresponding relationship between the downlink time offset estimation value and the uplink time offset estimation value of the uplink between the non-terrestrial network node and the terminal, and / or determine the uplink frequency offset estimation value according to the corresponding relationship between the downlink frequency offset estimation value and the uplink frequency offset estimation value of the uplink.

14. An apparatus for estimating uplink timing offset and / or frequency offset, characterized in that, Applied to a non-terrestrial network node, the apparatus includes: A sending module, configured to send a Chirp signal to a terminal, so that the terminal determines a downlink time offset estimation value and a downlink frequency offset estimation value of a downlink between the non-terrestrial network node and the terminal based on the Chirp signal, and determines the uplink time offset estimation value according to the corresponding relationship between the downlink time offset estimation value and the uplink time offset estimation value of the uplink between the non-terrestrial network node and the terminal, and / or determines the uplink frequency offset estimation value according to the corresponding relationship between the downlink frequency offset estimation value and the uplink frequency offset estimation value of the uplink.

15. An electronic device, characterized in that, Comprising a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory complete mutual communication through the communication bus; The memory is used for storing a computer program; The processor is configured to implement the method steps described in any one of claims 1-12 when executing the program stored on the memory.

16. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, and when the computer program is executed by the processor, the method steps described in any one of claims 1-12 are implemented.

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