Frequency offset estimation method and device

Abstract

The embodiment of the invention provides a frequency offset estimation method and device, and relates to the technical field of wireless communication and the like, and the method comprises the steps: obtaining time domain channel impulse responses CIR corresponding to two pilot symbols respectively; obtaining noise power according to the CIR corresponding to each of the two pilot symbols; when a power delay spectrum PDP is detected by the CIRs corresponding to the two pilot symbols, determining 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; according to the method, the frequency offset estimation value between the two pilot symbols is determined according to the CIR noise reduction component corresponding to the effective diameter of the two pilot symbols, noise reduction is performed on the CIR component corresponding to the effective diameter, and accurate elimination of noise in the CIR component is realized, so that the accuracy of the frequency offset estimation value is improved.

Description

Technical Field

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

[0002] In the process of wireless communication, the signal will be affected by the Doppler effect caused by the movement of the receiving end or the transmitting end, and the mismatch of the crystal frequency between the receiving end and the transmitting end, resulting in a frequency offset (FO) between the carrier frequency of the signal received by the receiving end and the local crystal frequency of the receiver. In order to improve the signal quality, the signal frequency offset is usually estimated.

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

[0004] In the above-mentioned related technologies, the smoothing and denoising process is performed on the CIR, but the noise in the CIR cannot be accurately and effectively filtered out, resulting in 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 device for improving the accuracy of the frequency offset estimation value.

[0006] In a first aspect, an embodiment of the present application provides a frequency offset estimation method, including:

[0007] 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;

[0008] Obtaining noise power according to the CIRs corresponding to the two pilot symbols;

[0009] 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;

[0010] 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.

[0011] In an optional implementation, 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 component corresponding to the effective path of the two pilot symbols includes:

[0012] Determine a 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, 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.

[0014] In an optional implementation, 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] Determine a power sum of the power corresponding to the effective path and the noise power;

[0016] 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.

[0017] In an optional implementation, 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] 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.

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

[0020] 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;

[0021] The frequency offset estimation value is determined according to the phase estimation value.

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

[0023] 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;

[0024] The frequency offset estimation value is determined 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 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;

[0027] A second acquisition module is used to acquire noise power according to the CIRs corresponding to the two pilot symbols respectively;

[0028] A determination module is used to determine the CIR noise reduction component corresponding to the effective path of the two pilot symbols based on 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 when a power delay spectrum PDP is detected according to the CIR corresponding to each 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.

[0029] The determination module is further 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.

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

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

[0032] 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.

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

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

[0035] 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.

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

[0037] 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.

[0038] In an optional implementation, the determination module is specifically configured to:

[0039] 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;

[0040] The frequency offset estimation value is determined according to the phase estimation value.

[0041] In an optional implementation, the determination module is further configured to:

[0042] 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;

[0043] The frequency offset estimation value is determined 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] Memory stores computer-executable instructions;

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

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

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

[0049] The embodiment of the present application provides a frequency offset estimation method and device. When a PDP is detected based on the CIR of two pilot symbols, the CIR noise reduction components corresponding to the effective paths of the two pilot symbols are determined by using 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, and weighted noise reduction processing is performed on the CIR components corresponding to the effective paths. This method can statistically approximate the optimal channel estimation. Furthermore, based on 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, and the influence of the invalid path on the frequency offset estimation value is effectively filtered out, 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, a brief introduction will be given below to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

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

[0052] Figure 2 One of the flow charts of the frequency offset estimation method provided in the embodiment of the present application;

[0053] Figure 3 A second flowchart of a frequency offset estimation method provided in an embodiment of the present application;

[0054] Figure 4 A schematic diagram of the structure of a frequency offset estimation device provided in an embodiment of the present application;

[0055] Figure 5 A schematic diagram of the structure of a frequency offset estimation device provided in an embodiment of the present application.

[0056] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope 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

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

[0058] First, the relevant terms involved in this application are explained.

[0059] Terminal equipment refers to equipment that includes wireless transceiver functions and can cooperate with network equipment to provide communication services to users. Terminal equipment is, for example, user equipment (UE), access terminal equipment, user unit, user station, mobile station, mobile station, remote station, remote terminal equipment, mobile equipment, user terminal equipment, wireless communication equipment, user agent or user device.

[0060] Network equipment, equipment that provides communication services to terminal equipment. Network equipment is, for example, a base station (Base Transceiver Station, BTS) in a Global System for Mobile Communication (GSM) system or a Code Division Multiple Access (CDMA) communication system, or a base station (NodeB, NB) in a Wideband Code Division Multiple Access (WCDMA) communication system, an evolved NodeB (eNB or eNodeB) in a Long Term Evolution (LTE) communication system, or a base station (gNB) in a 5G network, or a base station in a future network (such as a 6G network), or a base station or satellite in a non-terrestrial network (NTN) communication system.

[0061] Other terms:

[0062] In the present application, the term "include" and its variations may refer to non-restrictive inclusion; the term "or" and its variations may refer to "and / or". In the present application, the terms "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. In the present application, the term "plurality" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. In the present application, the term "at least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c can represent: a, b, c, ab, a--c, bc, or abc, where a, b, c can be single or multiple.

[0063] In this application, the terms "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in this application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a concrete way. "Under the circumstances of" or "when" are used to indicate a condition.

[0064] Next, a related method of frequency offset estimation is exemplified.

[0065] Figure 1 A flowchart of an existing method for frequency offset estimation provided by the present application is shown below. Figure 1 As shown, it includes: an RF 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 (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 RF front-end module is used to process the input signal to obtain the RF front-end output signal, wherein 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] The DFE module is used to process the RF front-end output signal to obtain a first baseband digital signal, wherein the processing includes but is not limited to: digital down-conversion processing, filtering processing, gain control processing, equalization processing, etc.

[0068] The synchronization signal processing module is used to perform initial time-frequency synchronization, coarse frequency offset estimation, and fine frequency offset estimation according to the first baseband digital signal to obtain synchronization information. The initial time-frequency synchronization includes symbol timing synchronization, Pulser 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] The DFE module is used to adjust the first baseband digital signal according to the synchronization information to obtain the second baseband digital signal.

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

[0071] The LS estimation module is used to perform channel estimation (eg, LS estimation) on the frequency domain received signal to obtain a first channel frequency domain response (Channel Frequency Response, CFR).

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

[0073] The time domain noise reduction module is used to perform noise reduction processing on the CIR to obtain the CIR after noise reduction processing.

[0074] The second FFT module is used to perform FFT on the CIR after the noise reduction process to obtain a second CFR.

[0075] The frequency domain frequency offset estimation module is used to estimate the frequency offset of the second CFR to obtain a frequency offset estimation value.

[0076] The DFE module performs frequency offset compensation on the second baseband digital signal according to the frequency offset estimation value to obtain a third baseband digital signal.

[0077] exist Figure 1 In the process of noise reduction processing on CIR by the time domain noise reduction module, an indiscriminate noise reduction processing method is usually adopted, that is, noise reduction processing is performed on CIR components corresponding to all paths. This indiscriminate noise reduction processing method does not distinguish between the CIR components corresponding to the effective path and the CIR components corresponding to the invalid path in the multipath, that is, the influence of the invalid path on the frequency offset estimation value is not filtered out, so it is difficult to achieve accurate noise reduction processing, resulting in low accuracy of the frequency offset estimation value. Moreover, after the noise reduction processing, FFT and frequency domain frequency offset estimation are required, resulting in high complexity in obtaining the frequency offset estimation value.

[0078] In view of this, an embodiment of the present application provides a frequency offset estimation method, in which a CIR component corresponding to a valid path is identified from a CIR, and a frequency offset estimation value is obtained based on the CIR component corresponding to the valid path, thereby avoiding the influence of an invalid path 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 embodiment of the present application provides a frequency offset estimation method 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 specific embodiments are used to describe in detail the technical solution of the present application and how the technical solution of the present application solves the above technical problems. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0081] Figure 2 This is a flow chart of a frequency offset estimation method provided in an embodiment of the present application. Figure 2 As shown, the method includes:

[0082] S201. Obtain CIRs corresponding to two pilot symbols respectively, where the CIRs include CIR components corresponding to multipaths, where multipaths are multiple transmission paths of the pilot symbols.

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

[0084] The frequency offset estimation device may 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 into which the pilot is inserted. The pilot includes one or more of the following: a demodulation reference signal (DMRS) of a broadcast channel, a demodulation reference signal (DMRS) of a data channel, and a tracking reference signal (TRS).

[0086] The two pilot symbols are two adjacent pilot symbols, or two non-adjacent pilot symbols, among a plurality of pilot symbols.

[0087] A plurality of pilot symbols are located in a transmission time slot (Transmission Time Interval, TTI).

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

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

[0090] In some embodiments, obtaining a CIR corresponding to each pilot symbol in a TTI includes:

[0091] According to the timing synchronization position of the PSS in the synchronization information, a baseband digital signal (which may be referred to as a time domain received signal) having a time length equal to one TTI is intercepted from the second baseband digital signal or the third baseband digital signal;

[0092] From a time domain received signal of a TTI, obtaining a time domain received signal corresponding to all OFDM symbols in a TTI;

[0093] Deleting the time domain received signal corresponding to the cyclic prefix (CP) from the time domain received signal corresponding to all OFDM symbols to obtain the valid time domain received signal 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] Determining a plurality of pilot symbols in all OFDM symbols;

[0096] Obtaining frequency domain received signals corresponding to multiple pilot symbols from frequency domain received signals corresponding to all OFDM symbols;

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

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

[0099]

[0100] in, represents the LS channel estimation 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 the pilot symbol i, 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] Among them, h i,k represents the ideal frequency domain channel coefficient, n i,k is Gaussian white noise.

[0103] Specifically, the CIR corresponding to the pilot symbol i includes the CIR component corresponding to the multipath, and the LS channel estimation value corresponding to the pilot symbol i and the CIR component corresponding to the pilot symbol i satisfy the following formula 3:

[0104]

[0105] Among them, g i,l It 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 multipaths, J represents the imaginary unit, and π represents the circumference of a circle.

[0106] Specifically, the CIR corresponding to the pilot symbol j includes the CIR component corresponding to the multipath, and the LS channel estimation value corresponding to the pilot symbol j and the CIR component corresponding to the pilot symbol j satisfy the following formula 4:

[0107]

[0108] Among them, g j,l Represents the CIR component corresponding to the lth path of pilot symbol j, l = 0, 1, ... N-1.

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

[0110] In some embodiments, a method for obtaining noise power according to the CIRs corresponding to the two pilot symbols may refer to related technologies and will not be described in detail here.

[0111] S203. When a power delay profile (PDP) is detected according to the CIR corresponding to each of the two pilot symbols, the CIR noise reduction components corresponding to the effective paths of the two pilot symbols are determined 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.

[0112] The PDP includes the power corresponding to the multipath, and the multipath includes the effective path and the ineffective path.

[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, a path in the multipath whose power is greater than a preset power is determined as a valid path; a path in the multipath whose power is equal to the preset power is determined as an invalid path, or a path in the multipath other than the invalid path is determined as a valid path.

[0115] For the lth path in the multipath, l = 0, 1, ... N-1; when the two pilot symbols include pilot symbol i and pilot symbol j, determine the power p corresponding to the lth path l ,include:

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

[0117] The CIR component g corresponding to the lth path i,l and the CIR component g corresponding to the lth path j,l The statistical average value of is determined as the average power corresponding to the lth path;

[0118] Subtract the noise power σ from the average power corresponding to the lth path 2 , and obtain the power p corresponding to the lth path l .

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

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

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

[0122]

[0123] Among them, E represents the mathematical expectation, E(g l ·g l * ) represents the average power corresponding to the first path, g l represents the CIR component corresponding to the lth path of any pilot symbol, g l * Represents the conjugate of the CIR component corresponding to the lth path of any pilot symbol.

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

[0125] The frequency offset estimate is an estimate of the frequency offset between two pilot symbols.

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

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

[0128]

[0129] in, represents the frequency offset estimate, represents the phase estimate,

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

[0131] exist Figure 2 In the frequency offset estimation method provided in the embodiment, the CIR noise reduction component corresponding to the effective path of the two pilot symbols is determined by using 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, and weighted noise reduction processing of the CIR component corresponding to the effective path is implemented, which can statistically approximate the optimal channel estimation. Furthermore, according to the CIR noise reduction component corresponding to the effective path of the two pilot symbols, the frequency offset estimation value between the two pilot symbols is determined, and the influence of the invalid path on the frequency offset estimation value is effectively filtered out, thereby improving the accuracy of the frequency offset estimation value.

[0132] For example, in a low-orbit satellite communication scenario, when CFR is obtained through IFFT to obtain CIR, only a few paths are effective paths, and the rest are noise. If the CIR is smoothed and denoised (i.e., indifferent smoothing and denoising is performed), more noise will be introduced because the effective path cannot be identified, resulting in a lower accuracy of the frequency offset estimate. In the present application, according to the noise power and the power corresponding to the effective path 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, and the frequency offset estimate between the two pilot symbols is determined based on the CIR denoised components corresponding to the effective paths of the two pilot symbols, so as to obtain the frequency offset estimate based on the CIR components corresponding to the effective paths after the effective path is identified, thereby avoiding the introduction of excessive noise and improving the accuracy of the frequency offset estimate.

[0133] Figure 3 The second flow chart of the frequency offset estimation method provided in the embodiment of the present application is as follows. Figure 3 As shown, the method includes:

[0134] S301. Obtain CIRs corresponding to two pilot symbols respectively, where the CIRs include CIR components corresponding to multipaths, where multipaths are multiple transmission paths of the pilot symbols.

[0135] S302: Obtain noise power according to CIRs corresponding to two pilot symbols.

[0136] S303: When the PDP is detected according to the CIRs corresponding to 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, the power sum of the power corresponding to the effective path and the noise power is determined; and the ratio of the power corresponding to the effective path to the power sum is determined as the noise reduction coefficient corresponding to the effective path.

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

[0139]

[0140] Among them, l 1 represents the effective diameter, represents the noise reduction coefficient corresponding to the effective diameter, represents the power corresponding to the effective diameter,

[0141] It should be noted that, in the embodiments of the present application, 2 Indicates invalid path, l 2 ∈l,

[0142] Optionally, the noise reduction coefficient corresponding to the effective path may be referred to as a minimum mean square error (MMSE) weighting coefficient.

[0143] S304: For each pilot symbol, perform noise reduction processing according to 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 the pilot symbol i, and the CIR noise reduction component corresponding to the effective path of the pilot symbol i satisfy the following formula 8:

[0146]

[0147] in, 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] in, 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 an embodiment of the present application, 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. This can achieve accurate 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 a phase estimation value between two pilot symbols according to CIR noise reduction components corresponding to 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] in, represents the phase estimate, angle represents the extracted complex phase function, represents the conjugate of the CIR noise reduction component corresponding to the effective path of pilot symbol i.

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

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

[0158] exist Figure 3 In the frequency offset estimation method provided in the embodiment, the noise power and the power corresponding to the effective path in the PDP are used to determine the noise reduction coefficient corresponding to the effective path. 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 multiplied to determine the CIR noise reduction component corresponding to the effective path of the pilot symbol. This achieves the purpose of performing noise reduction processing on the CIR component corresponding to the effective path of the pilot symbol without performing noise reduction processing on the CIR noise reduction component corresponding to the invalid path, thereby 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 high complexity in obtaining the frequency offset estimation value, which makes the power consumption of the baseband processing chip large and the efficiency of obtaining the frequency offset estimation value low. In the embodiment of the present application, the frequency offset estimation value between the two pilot symbols is determined according to the CIR noise reduction component corresponding to the effective path of the two pilot symbols, thereby avoiding FFT operation and frequency domain frequency offset estimation, reducing the complexity of obtaining the frequency offset estimation value, thereby reducing the power consumption of the baseband processing chip and improving the efficiency of obtaining the frequency offset estimation value.

[0160] In some cases (eg, the initial access phase or the PDP filter restart), the PDP may not be detected. The PDP filter may use the method of S202 above to detect the PDP.

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

[0162] For another example, it is usually necessary to obtain the PDP based on the average power corresponding to the multipaths. However, when the PDP filter is restarted, the average power corresponding to the multipaths cannot be obtained, so the PDP cannot be detected.

[0163] When the power delay spectrum PDP is not detected according to the CIR corresponding to each of the two pilot symbols, correlation processing is performed on the CIR components corresponding to the preset paths of the two pilot symbols; phase estimation is performed on the result of the correlation processing to obtain a phase estimation value; and based on the phase estimation value, a frequency offset estimation value between the two pilot symbols is determined.

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

[0165]

[0166] Among them, l 3 Indicates the preset diameter, l 3 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 embodiment of the present application, when PDP is not detected, the phase estimation value between the two pilot symbols is determined according to the CIR component corresponding to the preset path of the two pilot symbols; based on the phase estimation value, the frequency offset estimation value between the two pilot symbols is determined, thereby adding a method for determining the frequency offset estimation value when PDP is not detected, thereby improving the robustness of the frequency offset estimation method provided in the embodiment of the present application.

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

[0169]

[0170] in, 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 smoothed noise reduction coefficient of 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 meet the MMSE criterion.

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

[0173] Based on the same technical concept, the present application also provides a frequency offset estimation device. The frequency offset estimation device can implement the functions of the above-mentioned embodiments. Figure 4 The frequency offset estimation device provided in the embodiment of the present application is described.

[0174] Figure 4 Schematic diagram of the structure of the frequency offset estimation device provided in the embodiment of the present application. Figure 4 As shown, the frequency offset estimation device 40 includes:

[0175] The first acquisition module 401 is used to acquire the 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;

[0176] A second acquisition module 402 is used to acquire noise power according to the CIRs corresponding to the two pilot symbols;

[0177] The determination module 403 is used to determine 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 component corresponding to the effective path of the two pilot symbols when the power delay spectrum PDP is detected according to the CIR corresponding to each 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;

[0178] The determination module 403 is configured to determine a 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.

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

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

[0181] 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.

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

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

[0184] 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.

[0185] In an optional implementation manner, the determination module 403 is specifically configured to:

[0186] 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.

[0187] In an optional implementation manner, the determination module 403 is specifically configured to:

[0188] 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;

[0189] The frequency offset estimation value is determined according to the phase estimation value.

[0190] In an optional implementation, the determination module 403 is further configured to:

[0191] 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;

[0192] The frequency offset estimation value is determined according to the phase estimation value.

[0193] It should be noted here that the above-mentioned frequency offset estimation device 40 provided in the embodiment of the present application can implement all the method steps implemented in the above-mentioned method embodiment, and can achieve the same technical effect. The parts and beneficial effects of this embodiment that are the same as the method embodiment will not be described in detail here.

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

[0195] Figure 5 This is a schematic diagram of the structure of the frequency offset estimation device provided in the embodiment of the present application. Figure 5 As 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 connected to each other 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 each of the above method embodiments can be completed by hardware related to program instructions. The aforementioned program can be stored in a readable memory. When the program is executed, the steps of each of the above method embodiments are executed; and the aforementioned memory (storage medium) includes: read-only memory (ROM), RAM, flash memory, hard disk, solid state drive, magnetic tape, floppy disk, optical disk and any combination thereof.

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

[0200] An embodiment of the present application provides a storage medium, in which computer execution instructions are stored. When the computer execution instructions are executed by a processor, the method of the above method embodiment is used to implement the method.

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

[0202] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0203] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0204] Those skilled in the art may 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 equivalents, 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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