Frequency offset estimation method and device

Abstract

An embodiment of the present application provides a frequency offset estimation method and apparatus, which relate to the technical fields such as wireless communication. The method includes: obtaining the time-domain channel impulse response (CIR) corresponding to each of two pilot symbols; obtaining the noise power according to the CIR corresponding to each of the two pilot symbols; when the power delay profile (PDP) is detected in the CIR corresponding to each of the two pilot symbols, determining the CIR noise reduction components corresponding to the effective paths of the two pilot symbols according to the noise power, the power corresponding to the effective paths in the PDP, and the CIR components corresponding to the effective paths of the two pilot symbols; determining the frequency offset estimation value between the two pilot symbols according to the CIR noise reduction components corresponding to the effective paths of the two pilot symbols. By reducing the noise of the CIR components corresponding to the effective paths, accurate elimination of the noise in the CIR components is achieved, thereby improving the accuracy of the frequency offset estimation value.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical fields such as wireless communication, and in particular, to a frequency offset estimation method and apparatus. Background Art

[0002] In the process of wireless communication, the signal is affected by factors such as the Doppler effect caused by the movement of the receiving end or the transmitting end, and the mismatch between the crystal oscillator frequencies of the receiving end and the transmitting end, resulting in a frequency offset (Frequency Offset, FO) between the carrier frequency of the signal received by the receiving end and the local crystal oscillator frequency of the receiver. In order to improve the signal quality, frequency offset estimation is usually performed on the signal.

[0003] In the related art, frequency offset estimation includes: obtaining the time-domain channel impulse response (Channel Impulse Response, CIR) of the signal, performing smoothing and denoising processing on the CIR, and determining the frequency offset estimation value according to the result of the smoothing and denoising processing.

[0004] In the above-mentioned related art, when performing smoothing and denoising processing on the CIR, the noise in the CIR cannot be accurately and effectively filtered, resulting in a low accuracy of the frequency offset estimation value. Summary of the Invention

[0005] The embodiments of the present application provide a frequency offset estimation method and apparatus for improving the accuracy of the frequency offset estimation value.

[0006] In a first aspect, the embodiments of the present application provide a frequency offset estimation method, including:

[0007] Obtaining the time-domain channel impulse response CIR corresponding to each of two pilot symbols; wherein, the CIR includes CIR components corresponding to multiple paths, and the multiple paths are multiple transmission paths of the pilot symbol;

[0008] Obtaining the noise power according to the CIR corresponding to each of the two pilot symbols;

[0009] When the power delay profile PDP is detected according to the CIR corresponding to each of the two pilot symbols, determining the CIR noise reduction components corresponding to the valid paths of the two pilot symbols according to the noise power, the power corresponding to the valid paths in the PDP, and the CIR components corresponding to the valid paths of the two pilot symbols; wherein, the PDP includes the power corresponding to the multiple paths, the multiple paths include valid paths, and the power corresponding to the valid paths is greater than a preset power;

[0010] Determining the frequency offset estimation value between the two pilot symbols according to the CIR noise reduction components corresponding to the valid paths of the two pilot symbols.

[0011] In an alternative embodiment, determining the CIR noise reduction component corresponding to the effective path of the two pilot symbols according to the noise power, the power corresponding to the effective path in the PDP, and the CIR components corresponding to the effective paths of the two pilot symbols includes:

[0012] Determining the noise reduction coefficient corresponding to the effective path according to the noise power and the power corresponding to the effective path;

[0013] For each pilot symbol, determining the CIR noise reduction component corresponding to the effective path of the pilot symbol according to the noise reduction coefficient corresponding to the effective path and the CIR component corresponding to the effective path of the pilot symbol.

[0014] In an alternative embodiment, determining the noise reduction coefficient corresponding to the effective path according to the noise power and the power corresponding to the effective path includes:

[0015] Determining the power sum of the power corresponding to the effective path and the noise power;

[0016] Determining the ratio of the power corresponding to the effective path to the power sum as the noise reduction coefficient corresponding to the effective path.

[0017] In an alternative embodiment, determining the CIR noise reduction component corresponding to the effective path of the pilot symbol according to the noise reduction coefficient corresponding to the effective path and the CIR component corresponding to the effective path of the pilot symbol includes:

[0018] Determining the product of the noise reduction coefficient corresponding to the effective path and the CIR component corresponding to the effective path of the pilot symbol as the CIR noise reduction component corresponding to the effective path of the pilot symbol.

[0019] In an alternative embodiment, determining the frequency offset estimation value between the two pilot symbols according to the CIR noise reduction components corresponding to the effective paths of the two pilot symbols includes:

[0020] Determining the phase estimation value between the two pilot symbols according to the CIR noise reduction components corresponding to the effective paths of the two pilot symbols;

[0021] Determining the frequency offset estimation value according to the phase estimation value.

[0022] In an alternative embodiment, the method further includes:

[0023] In the case where the power delay profile PDP is not detected according to the CIR corresponding to each of the two pilot symbols, determining the phase estimation value between the two pilot symbols according to the CIR components corresponding to the preset paths of the two pilot symbols;

[0024] Determine the frequency offset estimation value according to the phase estimation value.

[0025] In a second aspect, an embodiment of the present application provides a frequency offset estimation device, including:

[0026] A first acquisition module, configured to acquire the time-domain channel impulse response CIR corresponding to each of two pilot symbols; wherein, the CIR includes CIR components corresponding to multiple paths, and the multiple paths are multiple transmission paths of the pilot symbols;

[0027] A second acquisition module, configured to acquire the noise power according to the CIR corresponding to each of the two pilot symbols;

[0028] A determination module, configured to, when detecting the power delay profile PDP according to the CIR corresponding to each of the two pilot symbols, determine the CIR noise reduction components corresponding to the valid paths of the two pilot symbols according to the noise power, the power corresponding to the valid paths in the PDP, and the CIR components corresponding to the valid paths of the two pilot symbols; wherein, the PDP includes the power corresponding to the multiple paths, the multiple paths include valid paths, and the power corresponding to the valid paths is greater than a preset power.

[0029] The determination module is further configured to determine the frequency offset estimation value between the two pilot symbols according to the CIR noise reduction components corresponding to the valid paths of the two pilot symbols.

[0030] In an optional implementation manner, the determination module is specifically configured to:

[0031] Determine the noise reduction coefficient corresponding to the valid path according to the noise power and the power corresponding to the valid path;

[0032] For each pilot symbol, determine the CIR noise reduction component corresponding to the valid path of the pilot symbol according to the noise reduction coefficient corresponding to the valid path and the CIR component corresponding to the valid path of the pilot symbol.

[0033] In an optional implementation manner, the determination module is specifically configured to:

[0034] Determine the sum of the power corresponding to the valid path and the noise power;

[0035] Determine the ratio of the power corresponding to the valid path to the sum of the powers as the noise reduction coefficient corresponding to the valid path.

[0036] In an optional implementation manner, the determination module is specifically configured to:

[0037] Determine the product of the noise reduction coefficient corresponding to the effective path and the CIR component corresponding to the effective path of the pilot symbol as the CIR noise reduction component corresponding to the effective path of the pilot symbol.

[0038] In an alternative embodiment, the determining module is specifically configured to:

[0039] Determine the phase estimation value between the two pilot symbols according to the CIR noise reduction components corresponding to the effective paths of the two pilot symbols;

[0040] Determine the frequency offset estimation value according to the phase estimation value.

[0041] In an alternative embodiment, the determining module is further configured to:

[0042] In the case where the power delay profile PDP is not detected according to the CIR corresponding to each of the two pilot symbols, determine the phase estimation value between the two pilot symbols according to the CIR components corresponding to the preset paths of the two pilot symbols;

[0043] Determine the frequency offset estimation value according to the phase estimation value.

[0044] In a third aspect, an embodiment of the present application provides a frequency offset estimation device, including: a memory and a processor;

[0045] The memory stores computer-executable instructions;

[0046] The processor executes the computer-executable instructions stored in the memory, so as to execute the method provided in any one of the first aspect.

[0047] In a fourth aspect, an embodiment of the present application provides a storage medium, in which computer-executable instructions are stored, and when the computer-executable instructions are executed by a processor, they are used to implement the method provided in any one of the first aspect.

[0048] In a fifth aspect, an embodiment of the present application provides a computer program product, including a computer program, and when the computer program is executed by a processor, it implements the method provided in any one of the first aspect.

[0049] The embodiments of the present application provide a frequency offset estimation method and apparatus. When the PDP is detected according to the CIR of two pilot symbols, the CIR noise reduction components corresponding to the effective paths of the two pilot symbols are determined through the noise power, the power corresponding to the effective paths in the PDP, and the CIR components corresponding to the effective paths of the two pilot symbols, so as to implement weighted noise reduction processing on the CIR components corresponding to the effective paths, and statistically approximate the optimal channel estimation. Further, according to the CIR noise reduction components corresponding to the effective paths of the two pilot symbols, the frequency offset estimation value between the two pilot symbols is determined, effectively filtering the influence of the invalid paths on the frequency offset estimation value, thereby improving the accuracy of the frequency offset estimation value. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions in the present application, the following briefly introduces the drawings required for the description of the embodiments. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0051] Figure 1 FIG. is a schematic flow chart of an existing method for frequency offset estimation provided by the present application;

[0052] Figure 2 FIG. is one of the schematic flow charts of the frequency offset estimation method provided by the embodiments of the present application;

[0053] Figure 3 FIG. is another schematic flow chart of the frequency offset estimation method provided by the embodiments of the present application;

[0054] Figure 4 FIG. is a schematic structural diagram of the frequency offset estimation apparatus provided by the embodiments of the present application;

[0055] Figure 5 FIG. is a schematic structural diagram of the frequency offset estimation device provided by the embodiments of the present application.

[0056] Through the above-mentioned drawings, the specific embodiments of the present application have been shown, and more detailed descriptions will be given later. These drawings and text descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0057] Exemplary embodiments will be described in detail herein, and examples thereof are shown in the accompanying drawings. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0058] First, related terms involved in the present application will be described.

[0059] A terminal device refers to a device that includes a wireless transceiver function and can cooperate with a network device to provide communication services for users. Examples of terminal devices include user equipment (UE), access terminal devices, user units, user stations, mobile stations, mobile handsets, remote stations, remote terminal devices, mobile devices, user terminal devices, wireless communication devices, user agents, or user devices, etc.

[0060] A network device is a device that provides communication services for terminal devices. Examples of network devices include base transceiver stations (BTS) in a Global System for Mobile Communication (GSM) system or a Code Division Multiple Access (CDMA) communication system, NodeBs (NBs) in a Wideband Code Division Multiple Access (WCDMA) communication system, evolved NodeBs (eNBs or eNodeBs) in a Long Term Evolution (LTE) communication system, gNBs in a 5G network, base stations in a future network (such as a 6G network), and also base stations or satellites in a Non-Terrestrial Network (NTN) communication system.

[0061] Other terms:

[0062] In this application, the term "including" and its variations may refer to non - restrictive inclusion; the term "or" and its variations may refer to "and / or". In this application, terms such as "first", "second", etc. are used to distinguish similar objects and do not necessarily describe a specific order or sequence. The term "plurality" in this application means two or more. "And / or" describes the relationship between related objects and indicates that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally indicates that the related objects before and after are in an "or" relationship. The term "at least one (item)" or its similar expressions in this application refer to any combination of these items, including any combination of single - item (item) or plural - item (items). For example, at least one (item) of a, b, or c can represent: a, b, c, a - b, a - c, b - c, or a - b - c, where a, b, c can be single or multiple.

[0063] In this application, words such as "exemplary" or "for example" are used to give examples, illustrations, or explanations. Any embodiment or design solution described as "exemplary" or "for example" in this application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of words such as "exemplary" or "for example" is intended to present relevant concepts in a specific way. "In the case of..." or "when..." etc. are used to represent a condition.

[0064] Next, an exemplary description of the related methods for frequency offset estimation is given.

[0065] Figure 1 It is a schematic flowchart of an existing method for frequency offset estimation provided in this application. Exemplarily, as Figure 1 shown, it includes: a radio frequency front - end module, a digital front - end (Digital Front End, DFE) module, a synchronization signal (Primary Synchronization Signal / Secondary Synchronization Signal, PSS / SSS) processing module, a first Fast Fourier Transform (Fast Fourier Transform, FFT) module, a Least Squares (LS) estimation module, an Inverse Fast Fourier Transform (Inverse Fast Fourier Transform, IFFT) module, a time - domain noise reduction module, a second FFT module, and a frequency - domain frequency offset estimation module.

[0066] The radio frequency front - end module is used to process the input signal to obtain a radio frequency front - end output signal, where the processing includes but is not limited to: filtering processing, signal amplification processing, noise suppression processing, mixing processing, analog - to - digital conversion processing, etc.

[0067] A DFE module is used to process the output signal of the radio frequency front end to obtain a first baseband digital signal. The processing includes, but is not limited to, digital down-conversion processing, filtering processing, gain control processing, equalization processing, etc.

[0068] A synchronization signal processing module is used to perform initial time-frequency synchronization, coarse frequency offset estimation, and fine frequency offset estimation based on the first baseband digital signal to obtain synchronization information. The initial time-frequency synchronization includes symbol timing synchronization, Doppler frequency offset capture, cell ID identification (to which the synchronization signal belongs), etc. The synchronization information includes, but is not limited to, the timing synchronization position of the PSS.

[0069] A DFE module is used to adjust the first baseband digital signal according to the synchronization information to obtain a second baseband digital signal.

[0070] A first FFT module is used to perform FFT on the second baseband signal to obtain a frequency-domain received signal.

[0071] An LS estimation module is used to perform channel estimation (such as LS estimation) on the frequency-domain received signal to obtain a first channel frequency response (CFR).

[0072] An IFFT module is used to perform IFFT on the CFR to obtain a CIR.

[0073] A time-domain noise reduction module is used to perform noise reduction processing on the CIR to obtain a noise-reduced CIR.

[0074] A second FFT module is used to perform FFT on the noise-reduced CIR to obtain a second CFR.

[0075] A frequency-domain frequency offset estimation module is used to perform frequency offset estimation on the second CFR to obtain a frequency offset estimation value.

[0076] A DFE module compensates the frequency offset of the second baseband digital signal according to the frequency offset estimation value to obtain a third baseband digital signal.

[0077] In Figure 1 the CIR includes CIR components corresponding to multiple paths. In the process of the time-domain noise reduction module performing noise reduction processing on the CIR, an undifferentiated noise reduction processing method is usually adopted, that is, noise reduction processing is performed on all CIR components corresponding to all paths. This undifferentiated noise reduction processing method does not distinguish between the CIR components corresponding to the effective paths and the CIR components corresponding to the invalid paths in the multiple paths, that is, it does not filter out the influence of the invalid paths on the frequency offset estimation value, so it is difficult to achieve precise noise reduction processing, resulting in a low accuracy of the frequency offset estimation value. Moreover, after the noise reduction processing, FFT and frequency-domain frequency offset estimation are still required, resulting in a high complexity of obtaining the frequency offset estimation value.

[0078] In view of this, an embodiment of the present application provides a frequency offset estimation method. In this method, the CIR components corresponding to the effective paths are identified from the CIR, and the frequency offset estimation value is obtained according to the CIR components corresponding to the effective paths, thereby avoiding the influence of the invalid paths on the frequency offset estimation value, improving the accuracy of the frequency offset estimation value, and reducing the complexity of obtaining the frequency offset estimation value.

[0079] It should be noted that the frequency offset estimation method provided by the embodiment of the present application is applicable to GSM systems, CDMA communication systems, WCDMA communication systems, LTE communication systems, and 5G communication systems, and is also applicable to future communication systems (such as 6G communication systems), and is also applicable to NTN communication systems, etc.

[0080] The following uses specific embodiments to elaborate in detail on the technical solution of the present application and how the technical solution of the present application solves the above technical problems. These several specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments.

[0081] Figure 2 It is one of the flow diagrams of the frequency offset estimation method provided by the embodiment of the present application. As Figure 2 shown, the method includes:

[0082] S201. Obtain the CIR corresponding to each of two pilot symbols. The CIR includes CIR components corresponding to multiple paths, and the multiple paths are multiple transmission paths of the pilot symbol.

[0083] Optionally, the execution subject of the frequency offset estimation method provided by the embodiment of the present application can be a frequency offset estimation device, or a frequency offset estimation device provided in the frequency offset estimation device. The frequency offset estimation device can be implemented by a combination of software and / or hardware.

[0084] The frequency offset estimation device can be, for example, a terminal device or a network device in the above communication system.

[0085] The pilot symbol is an Orthogonal Frequency Division Multiplexing (OFDM) symbol inserted with a pilot. The pilot includes one or more of the following: Demodulation Reference Signal (DMRS) of the broadcast channel, Demodulation Reference Signal (DMRS) of the data channel, and Tracking Reference Signal (TRS).

[0086] The two pilot symbols are two adjacent pilot symbols or two non - adjacent pilot symbols among multiple pilot symbols.

[0087] The multiple pilot symbols are located within one Transmission Time Interval (TTI).

[0088] Exemplarily, within one TTI, there are OFDM symbols 1, 2, 3, 4, 5, 6, and the multiple pilot symbols include OFDM symbols 1, 2, 3, and 5. When the two pilot symbols are two adjacent pilot symbols, the above two pilot symbols can include: OFDM symbol 1 and 2, or OFDM symbol 2 and 3, or OFDM symbol 3 and 5;

[0089] When the two pilot symbols are two non - adjacent pilot symbols, the above two pilot symbols can include: OFDM symbol 1 and 3, or OFDM symbol 2 and 3, etc.

[0090] In some embodiments, obtaining the CIR corresponding to each pilot symbol within one TTI includes:

[0091] According to the timing synchronization position of the PSS in the synchronization information, intercept a baseband digital signal with a time length equal to one TTI (which can be called the time - domain received signal) from the second baseband digital signal or the third baseband digital signal;

[0092] From the time - domain received signal of one TTI, obtain the time - domain received signals corresponding to all OFDM symbols in one TTI;

[0093] From the time - domain received signals corresponding to all OFDM symbols, delete the time - domain received signals corresponding to the Cyclic Prefix (CP) to obtain the effective time - domain received signals corresponding to all OFDM symbols;

[0094] Perform FFT on the effective time - domain received signals corresponding to all OFDM symbols to obtain the frequency - domain received signals corresponding to all OFDM symbols;

[0095] Determine multiple pilot symbols among all OFDM symbols;

[0096] From the frequency - domain received signals corresponding to all OFDM symbols, obtain the frequency - domain received signals corresponding to the multiple pilot symbols;

[0097] For each pilot symbol, perform LS estimation on the frequency - domain received signal corresponding to the pilot symbol to obtain the LS channel estimation value corresponding to the pilot symbol; perform N - point IFFT on the LS channel estimation value to obtain the CIR corresponding to the pilot symbol.

[0098] Specifically, the frequency-domain received signal corresponding to the pilot symbol and the LS channel estimate value corresponding to the pilot symbol satisfy the following formula 1:

[0099]

[0100] Wherein, represents the LS channel estimate value corresponding to pilot symbol i, y i,k represents the frequency-domain received signal corresponding to pilot symbol i, s i,k represents the local frequency-domain received signal corresponding to pilot symbol i, represents the conjugate signal of the local frequency-domain received signal, k represents the position of the subcarrier where the pilot is located on pilot symbol i, and i represents the position of the OFDM symbol into which the pilot is inserted (which can be used to identify the pilot symbol),

[0101] y i,k = h i,k s i,k + n i,k (Formula 2);

[0102] Wherein, h i,k represents the ideal frequency-domain channel coefficient, and n i,k is Gaussian white noise.

[0103] Specifically, the CIR corresponding to pilot symbol i includes CIR components corresponding to multiple paths. The LS channel estimate value corresponding to pilot symbol i and the CIR components corresponding to pilot symbol i satisfy the following formula 3:

[0104]

[0105] Wherein, g i,l represents the CIR component corresponding to the l-th path of pilot symbol i, l = 0, 1,... N-1, N represents the total number of multiple paths, J represents the imaginary unit, and π represents the pi.

[0106] Specifically, the CIR corresponding to pilot symbol j includes CIR components corresponding to multiple paths. The LS channel estimate value corresponding to pilot symbol j and the CIR components corresponding to pilot symbol j satisfy the following formula 4:

[0107]

[0108] Wherein, g j,l represents the CIR component corresponding to the l-th path of pilot symbol j, l = 0, 1,... N-1.

[0109] S202. Obtain the noise power according to the CIRs corresponding to two pilot symbols respectively.

[0110] In some embodiments, the method for obtaining the noise power according to the CIRs corresponding to two pilot symbols respectively may refer to the related art and will not be elaborated here.

[0111] S203. When the power delay profile (PDP) is detected according to the CIRs corresponding to two pilot symbols respectively, determine the CIR noise reduction components corresponding to the effective paths of the two pilot symbols according to the noise power, the power corresponding to the effective paths in the PDP, and the CIR components corresponding to the effective paths of the two pilot symbols.

[0112] The PDP includes the power corresponding to multiple paths, and the multiple paths include effective paths and ineffective paths.

[0113] The power corresponding to the effective path is greater than the preset power. The power corresponding to the ineffective path is equal to the preset power. The preset power is, for example, equal to 0.

[0114] In some embodiments, determine the path in the multiple paths with power greater than the preset power as the effective path; determine the path in the multiple paths with power equal to the preset power as the ineffective path, or determine the path in the multiple paths except the ineffective path as the effective path.

[0115] For the l-th path in the multiple paths, l = 0, 1, … N - 1; when the two pilot symbols include pilot symbol i and pilot symbol j, determine the power p l , including:

[0116] For the l-th path, obtain the CIR component g i,l corresponding to the l-th path from the CIR corresponding to pilot symbol i; obtain the CIR component g j,l corresponding to the l-th path from the CIR corresponding to pilot symbol j;

[0117] Determine the statistical average value of the CIR component g i,l corresponding to the l-th path and the CIR component g j,l corresponding to the l-th path as the average power corresponding to the l-th path;

[0118] Subtract the noise power σ 2 from the average power corresponding to the l-th path to obtain the power p l corresponding to the l-th path.

[0119] p l may be equal to the preset power or greater than the preset power.

[0120] In some embodiments, the PDP can be expressed as: p = {p l , l = 0, 1, … N - 1}.

[0121] Optionally, g i,l , gj,l and p l satisfy the following formula 5:

[0122]

[0123] where E represents the mathematical expectation, and E(g l ·g l * ) represents the average power corresponding to the l-th path, and g l represents the CIR component corresponding to the l-th path of any pilot symbol, and g l * represents the conjugate of the CIR component corresponding to the l-th path of any pilot symbol.

[0124] S204. Determine the frequency offset estimation value between two pilot symbols according to the CIR noise reduction components corresponding to the effective paths of the two pilot symbols.

[0125] The frequency offset estimation value is the estimated value of the frequency offset amount between two pilot symbols.

[0126] The frequency offset estimation value can be obtained according to the phase estimation value between two pilot symbols, and the phase estimation value is obtained according to the CIR noise reduction components corresponding to the effective paths of the two pilot symbols.

[0127] In some embodiments, the phase estimation value and the frequency offset estimation value satisfy the following formula 6:

[0128]

[0129] where represents the frequency offset estimation value, represents the phase estimation value,

[0130] Δn represents the number of sampling points corresponding to the time interval between pilot symbol i and pilot symbol j, where L cp,m is the length of the cyclic prefix of pilot symbol m, and pilot symbol m is between pilot symbol i and pilot symbol j.

[0131] In Figure 2 the frequency offset estimation method provided by the embodiment, by using the noise power, the power corresponding to the effective paths in the PDP, and the CIR components corresponding to the effective paths of two pilot symbols, determine the CIR noise reduction components corresponding to the effective paths of the two pilot symbols, and implement the weighted noise reduction processing for the CIR components corresponding to the effective paths, which can statistically approximate the optimal channel estimation. Further, according to the CIR noise reduction components corresponding to the effective paths of two pilot symbols, determine the frequency offset estimation value between the two pilot symbols, effectively filtering out the influence of the invalid paths on the frequency offset estimation value, thereby improving the accuracy of the frequency offset estimation value.

[0132] Exemplarily, in a low-earth orbit satellite communication scenario, when the CFR is subjected to IFFT to obtain the CIR, only a few paths are effective paths, and the remaining paths are all noise. If the CIR is smoothed and denoised (i.e., taking non-discriminatory smoothing and noise reduction), more noise will be introduced because the effective paths cannot be recognized, resulting in a low accuracy of the frequency offset estimation value. In this application, according to the noise power and the power corresponding to the effective paths in the PDP, the CIR components corresponding to the effective paths of the two pilot symbols are denoised to obtain the CIR denoised components corresponding to the effective paths of the two pilot symbols. According to the CIR denoised components corresponding to the effective paths of the two pilot symbols, the frequency offset estimation value between the two pilot symbols is determined, realizing that on the basis of recognizing the effective paths, according to the CIR components corresponding to the effective paths, the frequency offset estimation value is obtained, avoiding the introduction of too much noise, and improving the accuracy of the frequency offset estimation value.

[0133] Figure 3 This is the second flowchart of the frequency offset estimation method provided by the embodiments of the present application. As Figure 3 shown, the method includes:

[0134] S301. Obtain the CIR corresponding to each of the two pilot symbols. The CIR includes CIR components corresponding to multiple paths, and the multiple paths are multiple transmission paths of the pilot symbols.

[0135] S302. Obtain the noise power according to the CIR corresponding to each of the two pilot symbols.

[0136] S303. When the PDP is detected according to the CIR corresponding to each of the two pilot symbols, determine the noise reduction coefficient corresponding to the effective path according to the noise power and the power corresponding to the effective path in the PDP.

[0137] In some embodiments, determine the sum of the power corresponding to the effective path and the noise power; determine the ratio of the power corresponding to the effective path to the sum of the powers as the noise reduction coefficient corresponding to the effective path.

[0138] Specifically, the power corresponding to the effective path, the noise power, and the noise reduction coefficient corresponding to the effective path satisfy the following formula 7:

[0139]

[0140] where l1 represents the effective path, represents the noise reduction coefficient corresponding to the effective path, represents the power corresponding to the effective path,

[0141] It should be noted that in the embodiments of the present application, l2 represents the ineffective path, l2 ∈ l,

[0142] Optionally, the noise reduction coefficient corresponding to the effective path can be referred to as the Minimum Mean Square Error (MMSE) weighting coefficient.

[0143] S304. For each pilot symbol, perform noise reduction processing based on the noise reduction coefficient corresponding to the effective path and the CIR component corresponding to the effective path of the pilot symbol, and determine the CIR noise reduction component corresponding to the effective path of the pilot symbol.

[0144] In some embodiments, the product of the noise reduction coefficient corresponding to the effective path and the CIR component corresponding to the effective path of the pilot symbol is determined as the CIR noise reduction component corresponding to the effective path of the pilot symbol.

[0145] Specifically, the noise reduction coefficient corresponding to the effective path, the CIR component corresponding to the effective path of pilot symbol i, and the CIR noise reduction component corresponding to the effective path of pilot symbol i satisfy the following formula 8:

[0146]

[0147] Wherein, represents the CIR noise reduction component corresponding to the effective path of pilot symbol i, represents the CIR component corresponding to the effective path of pilot symbol i.

[0148] Specifically, the noise reduction coefficient corresponding to the effective path, the CIR component corresponding to the effective path of pilot symbol j, and the CIR noise reduction component corresponding to the effective path of pilot symbol j satisfy the following formula 9:

[0149]

[0150] Wherein, represents the CIR noise reduction component corresponding to the effective path of pilot symbol j, represents the CIR component corresponding to the effective path of pilot symbol j.

[0151] In the embodiments of the present application, determining the product of the noise reduction coefficient corresponding to the effective path and the CIR component corresponding to the effective path of the pilot symbol as the CIR noise reduction component corresponding to the effective path of the pilot symbol can achieve precise filtering of the noise in the effective path, thereby improving the accuracy of the frequency offset estimation value obtained based on the CIR noise reduction component.

[0152] S305. Determine the phase estimation value between two pilot symbols according to the CIR noise reduction components corresponding to the effective paths of the two pilot symbols.

[0153] Specifically, the CIR noise reduction component corresponding to the effective path of pilot symbol i, the CIR noise reduction component corresponding to the effective path of pilot symbol j, and the phase estimation value satisfy the following formula 10:

[0154]

[0155] Among them, represents the phase estimation value, and angle represents the function of extracting the complex phase. represents the conjugate of the CIR noise reduction component corresponding to the effective path of the pilot symbol i.

[0156] S306. Determine the frequency offset estimation value according to the phase estimation value.

[0157] Specifically, after obtaining the phase estimation value, the phase estimation value can be input into Equation 6 to obtain the frequency offset estimation value.

[0158] In Figure 3 In the frequency offset estimation method provided by the embodiment, the noise reduction coefficient corresponding to the effective path is determined by the noise power and the power corresponding to the effective path in the PDP. According to the noise reduction coefficient corresponding to the effective path, for each pilot symbol, the product of the noise reduction coefficient and the CIR component corresponding to the effective path of the pilot symbol is determined as the CIR noise reduction component corresponding to the effective path of the pilot symbol, achieving the purpose of noise reduction processing for the CIR component corresponding to the effective path of the pilot symbol, without the need to perform noise reduction processing on the CIR noise reduction component corresponding to the invalid path, eliminating the influence of the invalid path on the frequency offset estimation value, thereby improving the accuracy of the frequency offset estimation value.

[0159] In addition, in the related art, after obtaining the CIR, it is necessary to perform FFT and frequency domain frequency offset estimation again, resulting in a relatively high complexity of obtaining the frequency offset estimation value, a relatively large power consumption of the baseband processing chip, and a relatively low efficiency of obtaining the frequency offset estimation value. In the embodiment of the present application, the frequency offset estimation value between two pilot symbols is determined according to the CIR noise reduction components corresponding to the effective paths of the two pilot symbols, avoiding FFT operation and frequency domain frequency offset estimation, reducing the complexity of obtaining the frequency offset estimation value, further reducing the power consumption of the baseband processing chip, and improving the efficiency of obtaining the frequency offset estimation value.

[0160] In some cases (such as the initial access stage or PDP filter restart), the PDP may not be detected. The PDP filter can adopt the method of S202 above to detect the PDP.

[0161] For example, in the initial access stage, the reception of consecutive pilot symbols has not been completed, so it is impossible to detect an accurate PDP based on the CIR of a few pilot symbols.

[0162] For another example, usually, the PDP needs to be obtained according to the average power corresponding to multiple paths. When the PDP filter restarts, since the average power corresponding to multiple paths cannot be obtained, the situation where the PDP cannot be detected will occur.

[0163] In the case where the power delay profile PDP is not detected according to the CIRs corresponding to the two pilot symbols respectively, perform correlation processing on the CIR components corresponding to the preset paths of the two pilot symbols; perform phase estimation on the results of the correlation processing to obtain a phase estimation value; determine a frequency offset estimation value between the two pilot symbols according to the phase estimation value.

[0164] In the case where the power delay profile PDP is not detected according to the CIRs corresponding to the two pilot symbols respectively, the CIR noise reduction component corresponding to the preset path of pilot symbol i, the CIR noise reduction component corresponding to the preset path of pilot symbol j, and the phase estimation value satisfy the following formula 11:

[0165]

[0166] where l3 represents the preset path, and l3 ∈ l. It should be noted that when the PDP is not detected, the phase estimation value and the frequency offset estimation value also satisfy the above formula 6.

[0167] In the frequency offset estimation method provided in the embodiments of the present application, when the PDP is not detected, determine the phase estimation value between the two pilot symbols according to the CIR components corresponding to the preset paths of the two pilot symbols; determine the frequency offset estimation value between the two pilot symbols according to the phase estimation value, which adds a method for determining the frequency offset estimation value when the PDP is not detected and improves the robustness of the frequency offset estimation method provided in the embodiments of the present application.

[0168] In the prior art, when performing noise reduction processing on the CIR, the smoothing noise reduction coefficient is obtained based on the instantaneous channel impulse response and the instantaneous channel noise power. Among them, the smoothing noise reduction coefficient, the instantaneous channel impulse response, and the instantaneous channel noise power satisfy the following formula 12:

[0169]

[0170] where represents the smoothing noise reduction coefficient, represents the instantaneous channel impulse response, represents the instantaneous power of the instantaneous channel, represents the instantaneous channel noise power, and λ represents the weighted adjustment factor.

[0171] The MMSE criterion theoretically requires that the noise reduction coefficient must adopt the statistical power of the channel, while the smoothing noise reduction coefficient in the prior art (see formula 12) is obtained based on the instantaneous channel impulse response and the instantaneous channel noise power, which theoretically does not conform to the MMSE criterion.

[0172] In the frequency offset estimation method provided in the embodiments of the present application, the noise reduction coefficient corresponding to the effective path It is obtained based on the average power of each path rather than the instantaneous power of each path, so it conforms to the MMSE criterion and has more robust noise reduction performance.

[0173] Based on the same technical concept, an embodiment of the present application further provides a frequency offset estimation device. The frequency offset estimation device can implement the functions of the foregoing embodiments. The following will be combined with Figure 4 to describe the frequency offset estimation device provided in the embodiment of the present application.

[0174] Figure 4 It is a schematic structural diagram of the frequency offset estimation device provided in the embodiment of the present application. As Figure 4 shown, the frequency offset estimation device 40 includes:

[0175] A first acquisition module 401, configured to acquire the time-domain channel impulse response CIR corresponding to each of two pilot symbols; wherein, the CIR includes CIR components corresponding to multiple paths, and the multiple paths are multiple transmission paths of the pilot symbols;

[0176] A second acquisition module 402, configured to acquire the noise power according to the CIR corresponding to each of the two pilot symbols;

[0177] A determination module 403, configured to, when detecting the power delay profile PDP according to the CIR corresponding to each of the two pilot symbols, determine the CIR noise reduction components corresponding to the valid paths of the two pilot symbols according to the noise power, the power corresponding to the valid paths in the PDP, and the CIR components corresponding to the valid paths of the two pilot symbols; wherein, the PDP includes the power corresponding to the multiple paths, the multiple paths include valid paths, and the power corresponding to the valid paths is greater than a preset power;

[0178] A determination module 403, configured to determine the frequency offset estimation value between the two pilot symbols according to the CIR noise reduction components corresponding to the valid paths of the two pilot symbols.

[0179] In an optional implementation manner, the determination module 403 is specifically configured to:

[0180] Determine the noise reduction coefficient corresponding to the valid path according to the noise power and the power corresponding to the valid path;

[0181] For each pilot symbol, determine the CIR noise reduction component corresponding to the valid path of the pilot symbol according to the noise reduction coefficient corresponding to the valid path and the CIR component corresponding to the valid path of the pilot symbol.

[0182] In an optional implementation manner, the determination module 403 is specifically configured to:

[0183] Determine the sum of the power of the power corresponding to the valid path and the noise power;

[0184] Determine the ratio of the power corresponding to the effective diameter to the sum of the powers as the noise reduction coefficient corresponding to the effective diameter.

[0185] In an alternative embodiment, the determining module 403 is specifically configured to:

[0186] Determine the product of the noise reduction coefficient corresponding to the effective diameter and the CIR component corresponding to the effective diameter of the pilot symbol as the CIR noise reduction component corresponding to the effective diameter of the pilot symbol.

[0187] In an alternative embodiment, the determining module 403 is specifically configured to:

[0188] Determine the phase estimation value between the two pilot symbols according to the CIR noise reduction components corresponding to the effective diameters of the two pilot symbols;

[0189] Determine the frequency offset estimation value according to the phase estimation value.

[0190] In an alternative embodiment, the determining module 403 is further configured to:

[0191] In the case where the power delay profile PDP is not detected according to the CIR corresponding to the two pilot symbols, determine the phase estimation value between the two pilot symbols according to the CIR components corresponding to the preset diameters of the two pilot symbols;

[0192] Determine the frequency offset estimation value according to the phase estimation value.

[0193] It should be noted here that the above frequency offset estimation device 40 provided in the embodiments of the present application can implement all the method steps implemented in the above method embodiments and can achieve the same technical effects. The same parts and beneficial effects as those in the method embodiments in this embodiment will not be specifically described herein again.

[0194] It should be understood that the above frequency offset estimation device 40 is embodied in the form of functional modules. The term "module" here may refer to an application-specific integrated circuit (ASIC), an electronic circuit, a processor (such as a shared processor, a dedicated processor, or a group of processors, etc.) for executing one or more software or firmware programs, a memory, a combined logic circuit, and / or other suitable components that support the described functions.

[0195] Figure 5 It is a schematic structural diagram of the frequency offset estimation device provided in the embodiments of the present application. As Figure 5As shown, the frequency offset estimation device 50 may include: a memory 501 and a processor 502. Exemplarily, each part of the memory 501 and the processor 502 is interconnected via a bus 503.

[0196] The memory 501 is used to store program instructions.

[0197] The processor 502 is used to execute the program instructions stored in the memory, so as to enable the frequency offset estimation device to execute the above method.

[0198] All or part of the steps of implementing each of the above method embodiments may be completed by hardware related to program instructions. The foregoing program may be stored in a readable memory. When the program is executed, it executes the steps including each of the above method embodiments; and the foregoing memory (storage medium) includes: read-only memory (ROM), RAM, flash memory, hard disk, solid state drive, magnetic tape, floppy disk, optical disc, and any combination thereof.

[0199] All or part of the steps of implementing each of the above method embodiments may be completed by hardware related to program instructions. The foregoing program may be stored in a readable memory. When the program is executed, it executes the steps including each of the above method embodiments; and the foregoing memory (storage medium) includes: read-only memory (ROM), RAM, flash memory, hard disk, solid state drive, magnetic tape, floppy disk, optical disc, and any combination thereof.

[0200] An embodiment of the present application provides a storage medium, in which computer-executable instructions are stored, and when the computer-executable instructions are executed by a processor, they are used to implement the methods of the above method embodiments.

[0201] An embodiment of the present application further provides a computer program product, including a computer program, which when executed by a processor, can implement the methods shown in the above method embodiments.

[0202] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured article including an instruction device, and the instruction device implements the functions specified in one process Figure 1 one process or multiple processes and / or boxes Figure 1 functions specified in one box or multiple boxes.

[0203] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus, so that a series of operation steps are performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions for implementing the process Figure 1 in one process or a plurality of processes and / or boxes Figure 1 steps for the functions specified in one box or a plurality of boxes.

[0204] Those skilled in the art can make various changes and modifications to the embodiments of the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the embodiments of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these modifications and variations.

Claims

1. A frequency offset estimation method, characterized in that: include: Acquire a time domain channel impulse response CIR corresponding to each of the two pilot symbols; wherein the CIR includes a CIR component corresponding to a multipath, and the multipath is a plurality of transmission paths of the pilot symbol; Obtaining noise power according to the CIRs corresponding to the two pilot symbols; In the case where a power delay profile PDP is detected according to the CIRs corresponding to the two pilot symbols respectively, a CIR noise reduction component corresponding to the effective path of the two pilot symbols is determined according to the noise power, the power corresponding to the effective path in the PDP, and the CIR component corresponding to the effective path of the two pilot symbols; wherein the PDP includes the power corresponding to the multipath, the multipath includes the effective path, and the power corresponding to the effective path is greater than the preset power; A frequency offset estimation value between the two pilot symbols is determined according to the CIR noise reduction components corresponding to the effective paths of the two pilot symbols.

2. The method according to claim 1, characterized in that The determining, according to the noise power, the power corresponding to the effective path in the PDP, and the CIR component corresponding to the effective path of the two pilot symbols, the CIR noise reduction component corresponding to the effective path of the two pilot symbols comprises: Determine a noise reduction coefficient corresponding to the effective path according to the noise power and the power corresponding to the effective path; For each pilot symbol, a CIR noise reduction component corresponding to the effective path of the pilot symbol is determined according to the noise reduction coefficient corresponding to the effective path and the CIR component corresponding to the effective path of the pilot symbol.

3. The method according to claim 2, characterized in that The determining, according to the noise power and the power corresponding to the effective path, a noise reduction coefficient corresponding to the effective path, comprises: Determine a power sum of the power corresponding to the effective path and the noise power; The ratio of the power corresponding to the effective diameter to the power sum is determined as the noise reduction coefficient corresponding to the effective diameter.

4. The method according to claim 2, characterized in that: The determining, according to the noise reduction coefficient corresponding to the effective path and the CIR component corresponding to the effective path of the pilot symbol, a CIR noise reduction component corresponding to the effective path of the pilot symbol comprises: The product of the noise reduction coefficient corresponding to the effective path and the CIR component corresponding to the effective path of the pilot symbol is determined as the CIR noise reduction component corresponding to the effective path of the pilot symbol.

5. The method according to any one of claims 1 to 4, characterized in that: The determining, according to the CIR noise reduction component corresponding to the effective paths of the two pilot symbols, a frequency offset estimation value between the two pilot symbols comprises: Determine a phase estimation value between the two pilot symbols according to a CIR noise reduction component corresponding to the effective paths of the two pilot symbols; The frequency offset estimation value is determined according to the phase estimation value.

6. The method according to any one of claims 1 to 4, characterized in that: The method further comprises: In a case where the power delay profile PDP is not detected according to the CIRs corresponding to the two pilot symbols respectively, determining a phase estimation value between the two pilot symbols according to CIR components corresponding to the preset paths of the two pilot symbols; The frequency offset estimation value is determined according to the phase estimation value.

7. A frequency offset estimation device, characterized in that: include: A first acquisition module is used to acquire a time domain channel impulse response CIR corresponding to each of the two pilot symbols; wherein the CIR includes a CIR component corresponding to a multipath, and the multipath is a plurality of transmission paths of the pilot symbol; A second acquisition module is used to acquire noise power according to the CIRs corresponding to the two pilot symbols respectively; A determination module, configured to determine, when a power delay profile PDP is detected according to the CIRs corresponding to the two pilot symbols, a CIR noise reduction component corresponding to the effective path of the two pilot symbols according to the noise power, the power corresponding to the effective path in the PDP, and the CIR component corresponding to the effective path of the two pilot symbols; wherein the PDP includes the power corresponding to the multipath, the multipath includes the effective path, and the power corresponding to the effective path is greater than a preset power; The determination module is used to determine the frequency offset estimation value between the two pilot symbols according to the CIR noise reduction components corresponding to the effective paths of the two pilot symbols.

8. A frequency offset estimation device, characterized in that: include: Memory and processor; The memory stores computer-executable instructions; The processor executes the computer-executable instructions stored in the memory to implement the method according to any one of claims 1 to 6.

9. A storage medium, characterized in that: The storage medium stores computer-executable instructions, which are used to implement the method according to any one of claims 1 to 6 when executed by a processor.

10. A computer program product, characterized in that The invention comprises a computer program, which implements the method according to any one of claims 1 to 6 when being executed by a computer.

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