Frequency offset processing method and device and base station

Abstract

The embodiment of the invention provides a frequency offset processing method and device and a base station, and the method comprises the steps: for a data channel, calculating theoretical Doppler frequency offset, forming a frequency offset set, and carrying out the time domain frequency offset compensation operation on a received signal according to the frequency offset set; converting the compensated signal from a time domain to a frequency domain, and receiving the compensated signal to obtain a related estimated value; according to the validity judgment result of the frequency offset estimation value, performing frequency domain frequency offset compensation in different modes to obtain a detection result; for an access channel, theoretical Doppler frequency offset is calculated, a frequency offset set is formed, and time domain frequency offset compensation operation is executed on a received signal according to the frequency offset set; and converting the compensated signal from a time domain to a frequency domain, extracting an effective signal from the frequency domain, and receiving the extracted effective signal to obtain a detection result of the access channel. According to the invention, the frequency offset problem can be effectively solved, and the communication quality in a high-speed mobile scene is improved.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a frequency deviation processing method, device and base station. Background Art

[0002] With the rapid development of the high-speed rail industry, high-speed rail has become the preferred means of transportation for people, and the demand and quality requirements for wireless communication have increased significantly. However, the rapid movement of high-speed trains causes the Doppler frequency deviation to increase, which has a serious impact on the communication quality. In the data channel, the Doppler frequency deviation causes frequency domain signal distortion, OFDM (Orthogonal Frequency-Division Multiplexing) subcarrier orthogonality destruction and inter-carrier interference, which in turn affects the demodulation performance; in the access channel, the Doppler frequency deviation affects PRACH (Physical Random Access Channel) detection and delay estimation, resulting in user access difficulties. In addition, in the scenario of multi-user high-speed movement, the difference in Doppler frequency deviation will cause multi-user frequency domain interference, further reducing the signal-to-noise ratio. Summary of the invention

[0003] In order to improve the communication quality in high-speed mobile scenarios, the present application provides a frequency deviation processing method, device and base station.

[0004] In a first aspect, the present application provides a frequency offset processing method, for a data channel: calculating a theoretical Doppler frequency offset and forming a frequency offset set, performing a time domain frequency offset compensation operation on a received signal according to the frequency offset set; converting the compensated signal from the time domain to the frequency domain, and performing receiving processing to obtain a related estimated value; according to a validity judgment result of the frequency offset estimated value, using different methods to perform frequency domain frequency offset compensation to obtain a detection result; For the access channel: calculate the theoretical Doppler frequency offset and form a frequency offset set, and perform time domain frequency offset compensation on the received signal based on the frequency offset set; convert the compensated signal from the time domain to the frequency domain, extract the valid signal in the frequency domain, and receive and process the extracted valid signal to obtain the detection result of the access channel.

[0005] In a second aspect, the present application further provides a frequency offset processing device, a data channel processing module, which is used to calculate the theoretical Doppler frequency offset and form a frequency offset set, and perform a time domain frequency offset compensation operation on the received signal according to the frequency offset set; convert the compensated signal from the time domain to the frequency domain, and perform receiving processing to obtain a related estimated value; according to the validity judgment result of the frequency offset estimated value, use different methods to perform frequency domain frequency offset compensation, so as to obtain a detection result; The access channel processing module is used to calculate the theoretical Doppler frequency deviation and form a frequency deviation set, and perform time domain frequency deviation compensation operation on the received signal according to the frequency deviation set; convert the compensated signal from the time domain to the frequency domain, extract the effective signal in the frequency domain, and receive and process the extracted effective signal to obtain the detection result of the access channel.

[0006] In a third aspect, the present application further provides a base station, which is used to execute the steps of the frequency offset processing method as described in any one of the first aspects.

[0007] The embodiment of the present application provides a frequency deviation processing method, device and base station. In the high-speed mobile scenario, the method improves the communication quality by performing specific processing on the data channel and the access channel respectively. For the data channel, the theoretical Doppler frequency deviation is first calculated to form a frequency deviation set and the received signal is compensated for the frequency deviation in the time domain based on this. The compensated signal is then time-converted and received and processed to obtain the relevant estimated value. Then, different methods are used to perform frequency deviation compensation in the frequency domain according to the validity judgment result of the frequency deviation estimate to obtain the detection result. For the access channel, the frequency deviation set is also calculated first and the time-domain frequency deviation compensation is performed. Then, after time-conversion, the effective signal is extracted in the frequency domain and received and processed to obtain the detection result of the access channel. Through these steps, the frequency deviation is effectively processed, thereby solving the problem of communication quality degradation caused by frequency deviation in the high-speed mobile scenario.

[0008] Therefore, the present application can perform refined processing on the data channel and access channel in high-speed mobile scenarios respectively, and effectively address the frequency deviation problem by accurately calculating and compensating for the frequency deviation, and reasonably performing signal conversion and reception processing, thereby improving the communication quality in high-speed mobile scenarios and ensuring the accuracy and reliability of communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. 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 paying any creative work.

[0010] Figure 1 This is a schematic diagram of the Doppler frequency deviation produced by high-speed rail movement; Figure 2 is a schematic diagram of the peak position of the high-speed scene; Figure 3 is a flow chart of the frequency deviation processing method; Figure 4 is a flow chart of a frequency deviation processing method based on a data channel; Figure 5is a flow chart of a frequency deviation processing method based on an access channel; Figure 6 is a schematic diagram of the peak value relationship after the first frequency deviation processing; Figure 7 It is a structural block diagram of a frequency deviation processing device. DETAILED DESCRIPTION

[0011] In the embodiments of the present application, the term "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent three situations: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects before and after are in an "or" relationship. In the embodiments of the present application, the term "plurality" refers to two or more than two, and other quantifiers are similar.

[0012] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0013] According to the Doppler frequency shift formula ( is the carrier frequency, is the movement speed, is the azimuth, =The speed of light) shows that both the speed and direction of movement will affect the size of the Doppler frequency deviation. In a multi-user high-speed mobile scenario, the Doppler frequency deviation will destroy the orthogonality between subcarriers, thereby introducing additional interference between subcarriers, causing the user's signal-to-noise ratio to decrease, thereby affecting the user's reception performance. For example, when the train speed reaches 500km / h and the carrier frequency is 2.8GHz, the maximum Doppler frequency deviation calculated according to the above formula can reach 1296Hz, which seriously affects the reception and detection of uplink signals. It can be seen that it is necessary to overcome the influence of Doppler frequency deviation when the terminal moves at high speed.

[0014] Please refer to Figure 1 , Figure 1This is a schematic diagram of the Doppler frequency deviation caused by high-speed rail movement. Assume that there are N tracks, and the locomotive on each track is regarded as a train user. The time-frequency resources of these N train users do not overlap, but in high-speed scenarios, each train user will experience a large Doppler frequency deviation. The Doppler frequency deviation is a frequency change phenomenon caused by the relative motion between the communication equipment on the train and the base station. On the one hand, this Doppler frequency deviation destroys the orthogonality between subcarriers, and on the other hand, it causes energy leakage in the frequency domain. If train user i and train user j are in adjacent frequency domain positions, the frequency domain data of train user i may leak to the frequency domain of train user j, thereby causing frequency domain interference between multiple users on the train. In addition, the movement direction of each user (such as Figure 1 The arrows in the figure point to the direction), movement speed (v1, v2, …, v N ) and the angles with the base station (such as θ1, θ2, …, θ N ), which makes the Doppler frequency deviation generated by each train user different, and thus leads to different interference situations between train users.

[0015] Pilot data is a special type of signal data. It is a known signal pattern sent intentionally by the transmitter to assist the receiver in obtaining channel state information, achieving synchronization, and performing frequency offset estimation. The traditional frequency offset estimation method is based on pilot data and uses pilot data of multiple symbols to carry out frequency offset estimation. The operation process is as follows: First, extract the user's pilot data from the received signal; then, obtain the channel estimation value of each pilot symbol through channel estimation; then, select the channel estimation values ​​of two different pilot symbols for correlation calculation; then calculate the angle of the result after the correlation operation; after this series of operations, finally calculate the frequency offset estimation value. The frequency offset estimation value is the estimation result of the frequency offset size in the received signal. The receiver can perform subsequent frequency offset processing and other operations based on this estimation value, thereby improving the signal reception quality.

[0016] From the perspective of the overall architecture of the communication system, data channels and access channels are important components. In the data channel part, the traditional frequency offset estimation method related to pilot data has some limitations. On the one hand, when the pilot symbol interval is large, the frequency offset estimation range is reduced. In high-speed mobile scenarios, the Doppler frequency offset is large, and the actual frequency offset is easy to exceed the range, causing the traditional frequency offset estimation value to flip and the estimation to be inaccurate, thereby reducing the reception performance; on the other hand, traditional frequency offset processing is only for frequency domain signals and cannot solve the intra-symbol interference caused by Doppler frequency offset. In terms of access channels, traditional detection technology combines the main window and sub-window signals for preamble detection under the restricted set configuration, which will increase the background noise and reduce the detection performance. Although preamble detection under the unrestricted set can reduce base station costs, traditional detection methods cannot use unrestricted set access configurations in high-speed mobile scenarios.

[0017] In the frequency offset estimation process based on pilot data, first perform a fast Fourier transform (FFT) on the received time domain signal to convert it to the frequency domain. In the frequency domain, extract the received data for each pilot symbol and generate the corresponding transmitted pilot data. Subsequently, the channel estimation value of each pilot symbol is obtained by transmitting and receiving the pilot data. Next, the channel estimation values ​​of the two pilot symbols are selected for correlation operation, and then the angle of the result after the correlation operation is calculated to calculate the frequency offset. After obtaining the frequency offset, the frequency offset processing operation is performed in the frequency domain. The entire process, from frequency offset estimation to frequency offset processing, is completed in the frequency domain.

[0018] In the high-speed rail scenario, due to the high-speed operation of the train, a large Doppler frequency deviation will be generated. For the physical random access channel (PRACH), it is usually configured as a restricted set. When the Doppler frequency deviation satisfies the relationship When (where Indicates the subcarrier spacing of PRACH, Indicates Doppler frequency deviation), the received PRACH time domain signal will produce energy dispersion compared to the original sequence, and the dispersed position is located at The cyclic shift of for The cyclic shift value corresponding to the PRACH peak at time .

[0019] Based on the above cyclic shift phenomenon, in addition to the PRACH peak detection, ( In addition to the correlation peak at (where ) Department (including is the PRACH sequence length) a pseudo correlation peak appears. The search window where the correlation peak is located is defined as the main window, and the The search window is defined as a sub-window. In this way, A secondary window.

[0020] The 3GPP protocol defines two restriction sets, namely restricted Type A and restricted Type B. For restricted Type A, the Doppler frequency deviation it can resist is (K=1 at this time), in this case, two sub-windows will be generated (recorded as sub-window 1 / 2); and for restricted Type B, the Doppler frequency deviation that can be resisted is (K=2 at this time), in this case, 4 sub-windows will be generated (referred to as sub-windows 1, 2, 3, 4), such as Figure 2 As shown, Figure 2 The horizontal axis n (sc index) represents the time index, and the vertical axis MF_ Out(n)Represents the output result after matched filtering; N cs Indicates the offset related to the channel state; during PRACH peak detection, it will be v There is a correlation peak at v The search window where the correlation peak is located is defined as the main window. The traditional detection method for restricted TypeA / B is three-window merging / five-window merging, that is, superimposing the main window energy with the energy of all sub-windows, and then performing PRACH peak detection. Three-window merging is to superimpose the main window energy with the energy of these two sub-windows (restricted TypeA will produce two sub-windows); five-window merging is to superimpose the main window energy with the energy of these four sub-windows (restricted TypeB will produce four sub-windows).

[0021] Please refer to Figure 3 , Figure 3 A method for processing frequency offset includes frequency offset estimation and frequency offset compensation. The method includes: S110, for the data channel: calculate the theoretical Doppler frequency offset and form a frequency offset set, and perform a time domain frequency offset compensation operation on the received signal based on the frequency offset set; convert the compensated signal from the time domain to the frequency domain, and perform reception processing to obtain a related estimated value; based on the validity judgment result of the frequency offset estimate, use different methods to perform frequency domain frequency offset compensation to obtain a detection result.

[0022] Exemplarily, calculating the theoretical Doppler frequency offset and forming a frequency offset set, and performing a time-domain frequency offset compensation operation on the received signal according to the frequency offset set includes: S111, according to the position information, movement speed, movement direction of the train and the position and height information of the base station, the corresponding theoretical Doppler frequency deviation is calculated for each train user to obtain a first frequency deviation set.

[0023] For example, the theoretical Doppler frequency deviation (i.e., the first frequency deviation estimate) is calculated based on the train position, movement speed and direction, and base station position and height. If the number of trains is N (i.e., N train users), then N first frequency offset estimates are obtained. , recorded as the first frequency offset set .

[0024] S112, using the frequency offset estimation value in the first frequency offset set and the received first time domain signal, perform a time domain frequency offset compensation operation on the theoretical Doppler frequency offset corresponding to each train user to obtain a compensated second time domain signal.

[0025] For example, according to the first frequency offset set The frequency offset estimation value in the first time domain signal (received signal) is used to Users Perform time domain frequency offset compensation to obtain a second time domain signal.

[0026] Exemplarily, converting the compensated signal from the time domain to the frequency domain, and performing receiving processing, and obtaining the relevant estimated value includes: S113, converting the second time domain signal from the time domain to the frequency domain to obtain a first frequency domain signal.

[0027] S114, receiving and processing the first frequency domain signal, wherein the receiving and processing includes estimating the channel characteristics, further estimating the frequency offset, and estimating the signal to interference and noise ratio, to obtain a new frequency offset estimation value and a first signal to interference and noise ratio estimation value for each train user, wherein the new frequency offset estimation values ​​constitute a second frequency offset set.

[0028] For example, the first frequency domain signal is used for receiving processing, including channel estimation, frequency offset estimation, and SINR (Signal to Interference plus Noise Ratio) estimation. The new frequency offset estimate of the train user (i.e., the second frequency offset estimate) , recorded as the second frequency offset set The elements, and the obtained The first SINR estimate of the train users.

[0029] Among them, SINR is an important indicator to measure the signal quality in the communication system. It reflects the ratio of signal strength to the sum of interference and noise strength. The higher the SINR value, the better the signal quality and the better the performance of the communication system.

[0030] Exemplarily, according to the validity judgment result of the frequency offset estimation value, frequency domain frequency offset compensation is performed in different ways, and the detection result is obtained, including: S115, if the absolute value of a new frequency deviation estimate of a train user is less than a preset estimate deviation threshold value, it is determined that the initial theoretical Doppler frequency deviation estimate (i.e., the first frequency deviation estimate) of the train user is valid, and the new frequency deviation estimate (i.e., the second frequency deviation estimate) has not flipped; the first frequency domain signal and the new frequency deviation estimate are used to perform a frequency domain frequency deviation compensation operation on the train user to obtain the detection result of the train user.

[0031] For example, according to the second frequency offset set calculated in S114 The Frequency deviation value , for the first frequency offset set In To judge the effectiveness: if , then determine the The first frequency offset estimate of the train users Valid, and the second frequency offset estimate No flipping occurred. is the preset estimated deviation threshold. At this time, the first frequency domain signal and the second frequency deviation set are used The Frequency deviation value , for The frequency domain frequency offset compensation is implemented for each train user, and the detection result of the train user is further obtained.

[0032] S116: If the absolute value of the new frequency deviation estimate of a train user is greater than a preset estimate deviation threshold, the first time domain signal is converted from the time domain to the frequency domain to obtain a second frequency domain signal, and then the second frequency domain signal is received and processed to obtain a second signal to interference and noise ratio estimate.

[0033] For example, if it does not meet , then determine the The first frequency offset estimate of the train users May be invalid for The train user uses the first time domain signal to perform time-to-frequency conversion to obtain a second frequency domain signal. Then the second frequency domain signal is used for receiving and processing to obtain the first The second SINR estimate of the train users.

[0034] Exemplarily, based on step S116, the method further includes: If the second signal to interference plus noise ratio estimation value is greater than the first signal to interference plus noise ratio estimation value, the second frequency domain signal is received and processed to obtain a detection result of the train user.

[0035] For example, if the second SINR estimate is greater than the first SINR estimate, it is considered that the first The first frequency offset estimate of the train users The second frequency domain signal is used to perform receiving processing and further obtain the detection result of the train user.

[0036] If the second signal to interference and noise ratio estimate value is less than or equal to the first signal to interference and noise ratio estimate value, it is determined that the initial theoretical Doppler frequency offset estimate value of the train user is valid, and a frequency domain frequency offset compensation operation is performed on the train user using the first frequency domain signal and the new frequency offset estimate value to obtain a detection result of the train user.

[0037] For example, if the second SINR estimate value is less than or equal to the first SINR estimate value, then it is determined that the first The first frequency offset estimate of the train users Valid. Use the first frequency domain signal and the second frequency offset set The Frequency deviation value ,right The frequency domain frequency offset compensation is implemented for each train user, and the detection result of the train user is further obtained.

[0038] Exemplarily, the method further includes: Repeat steps S112 to S116 to traverse the first frequency offset set All frequency deviation values ​​in the data channel are processed to complete the processing operation of the data channels of all train users.

[0039] S120, for the access channel: calculate the theoretical Doppler frequency deviation and form a frequency deviation set, and perform a time domain frequency deviation compensation operation on the received signal according to the frequency deviation set; convert the compensated signal from the time domain to the frequency domain, extract the valid signal in the frequency domain, and receive and process the extracted valid signal to obtain the detection result of the access channel.

[0040] Exemplarily, calculating the theoretical Doppler frequency offset and forming a frequency offset set, and performing a time-domain frequency offset compensation operation on the received signal according to the frequency offset set includes: S121, calculating the corresponding theoretical Doppler frequency deviation for each train user according to the train's position information, movement speed, movement direction, and the base station's position and height information, to obtain a first frequency deviation set.

[0041] For example, the theoretical Doppler frequency deviation is calculated based on the train position, speed and direction of movement, and the base station position and height. If the number of trains is N (i.e., N train users), then N first frequency offsets are obtained. , recorded as the first frequency offset set .

[0042] S122, using the frequency offset estimation value in the first frequency offset set and the received first time domain signal, perform a time domain frequency offset compensation operation on the theoretical Doppler frequency offset corresponding to each train user to obtain a compensated second time domain signal.

[0043] For example, according to the first frequency offset set The frequency offset estimation value in the first time domain signal (received signal) is used to Users Perform time domain frequency offset compensation to obtain a second time domain signal.

[0044] Exemplarily, converting the compensated signal from the time domain to the frequency domain, extracting the valid signal in the frequency domain, and receiving and processing the extracted valid signal, and obtaining the detection result of the access channel includes: S123: Convert the second time domain signal from the time domain to the frequency domain, and extract a valid physical random access channel frequency domain signal in the frequency domain.

[0045] S124, receiving and processing the extracted signal, the receiving and processing including matched filtering and preamble detection operations; when performing preamble detection, only the energy of the main window is used, and three-window merging or five-window merging operations are not performed. The user corresponding to the preamble detected by the main window is a valid user.

[0046] Specifically, PRACH is a channel in a wireless communication system for user equipment (such as a mobile phone) to initiate a random access request to a base station. When a user equipment needs to access the network, it will send a specific preamble sequence through PRACH, and the base station will identify and accept the user by detecting these preambles. In the traditional PRACH detection method, especially when a restricted set is configured, a three-window merging or five-window merging method is usually adopted. The purpose of the merging operation is to integrate the signal information in multiple windows to improve the accuracy and reliability of the detection. For example, by merging the signals of the main window and multiple sub-windows, and then performing preamble detection based on the merged signal, it is determined whether there is user access. The detection method provided in the present application no longer performs three-window merging or five-window merging operations, but only focuses on the peak in the main window. The peak in the main window usually represents the part with the strongest signal energy, that is, the part that is most likely to contain a valid preamble. For example, when analyzing the received PRACH signal, only the point with the largest signal strength (i.e., the peak) is found within the main window range.

[0047] When a peak is detected in the main window and the peak meets certain detection conditions (such as exceeding a preset threshold), it is considered that a valid preamble is detected, and accordingly, the user who sent the preamble is considered a valid user. This method of the present application simplifies the detection process and directly determines the valid user based on the detection result of the main window, avoiding some problems that may be caused by multi-window merging, such as noise floor increase.

[0048] Therefore, the detection method provided by the present application does not require complex multi-window merging operations, reduces the amount of calculation and processing time, improves detection efficiency, and is particularly suitable for scenarios with high real-time requirements. Since no window merging is performed, the problem of background noise increase that may be caused by the merging operation is avoided, thereby improving the accuracy and reliability of the detection, and being able to more effectively identify real valid users.

[0049] Exemplarily, the method further includes: Repeat steps S122 to S124 to traverse the first frequency offset set All frequency deviation values ​​in the data are used to complete the processing operation of the access channels of all train users.

[0050] In summary, the frequency offset processing method described in the present application can solve multiple problems related to frequency offset estimation and signal detection: First, when the pilot symbol interval is large, the frequency offset estimation range becomes smaller. In high-speed mobile scenarios, the actual frequency offset may exceed the range, causing the frequency offset estimation value of the traditional method to flip and become inaccurate, thereby reducing the reception performance; second, traditional frequency offset compensation is only performed on frequency domain signals, and cannot recover the intra-symbol interference caused by the user's Doppler frequency offset; third, when configuring a restricted set, the traditional detection technology combines the main window and the sub-window for preamble detection, which will increase the background noise and reduce the detection performance; fourth, although the preamble detection under the unrestricted set is simpler, easier to implement and can reduce the cost of the base station, in high-speed mobile scenarios, the traditional detection method cannot use the unrestricted set access configuration. Specifically: (1) The problem of small frequency offset estimation range and estimated value flipping can be solved as follows: a. Calculate the theoretical Doppler frequency deviation and compensate it in the time domain, that is, according to the position, speed, direction of the train and the position and height information of the base station, calculate the corresponding theoretical Doppler frequency deviation for each train user to form a first frequency deviation set. Use the frequency deviation estimation value in the set to compensate the time domain frequency deviation of the received first time domain signal to obtain the second time domain signal. In this way, the frequency deviation is compensated in the initial stage to prevent the actual frequency deviation from exceeding the estimation range.

[0051] b. Judgement of the validity of the frequency offset estimate and compensation adjustment, that is, converting the second time domain signal to the frequency domain to obtain the first frequency domain signal, performing receiving processing to obtain a new frequency offset estimate (constituting the second frequency offset set), a first signal to interference and noise ratio estimate, etc. If the absolute value of the new frequency offset estimate is less than the preset estimated deviation threshold, it is determined that the initial theoretical Doppler frequency offset estimate is valid and has not flipped, and the first frequency domain signal and the new estimate are used to perform frequency domain frequency offset compensation to obtain the detection result; if it is greater than the threshold, it is determined that the initial estimate may be invalid, and the final frequency offset compensation and detection method are determined by further comparing the signal to interference and noise ratio estimates under different processing. For example, the first time domain signal is reprocessed to obtain the second frequency domain signal and the second signal to interference and noise ratio estimate is received and processed to obtain the second signal to interference and noise ratio estimate. Whether the initial estimate is valid is determined based on its size relationship with the first signal to interference and noise ratio estimate, and then the appropriate frequency domain signal and estimate are selected to perform frequency offset compensation and obtain the detection result.

[0052] (3) The problem of irreversible intra-symbol interference can be solved as follows: Time domain frequency offset compensation, that is, the operation of forming a frequency offset set by calculating the theoretical Doppler frequency offset and performing time domain frequency offset compensation, processes the frequency offset in the time domain instead of relying solely on frequency domain frequency offset compensation. This can reduce the intra-symbol interference caused by Doppler frequency offset, because time domain compensation can more directly adjust the time characteristics of the signal, thereby improving the intra-symbol interference problem caused by frequency offset.

[0053] (3) The problem of increased noise floor caused by signal merging can be solved as follows: Simplify preamble detection, that is, when processing the second time domain signal, convert it to the frequency domain and extract the effective PRACH frequency domain signal. When performing matched filtering and preamble detection, only the main window energy is considered, and three-window merging or five-window merging operations are not performed. This avoids the problem of noise floor increase caused by signal merging, and the preamble detected by the main window is regarded as a valid user, which can detect the effective signal more accurately and improve the detection performance.

[0054] (4) The problem of being unable to use the unrestricted set access configuration in high-speed mobility scenarios is solved as follows: The optimized detection method, i.e. the preamble detection method that only considers the main window energy and does not perform window merging, improves the accuracy and efficiency of detection to a certain extent. This relatively simplified detection method is closer to the detection characteristics under the unrestricted set, making it possible to perform signal detection more effectively in high-speed mobile scenarios, thereby realizing unrestricted set access configuration and reducing base station costs.

[0055] The frequency deviation processing method of the present application is described in detail below through embodiments.

[0056] Please refer to Figure 4 , Figure 4 The flowchart of the frequency deviation processing method based on the data channel is as follows. A frequency deviation processing method includes: S401, calculating a first frequency offset estimation value of each train user to obtain a first frequency offset set.

[0057] Assume that the number of orbits is Assume that the preset movement speed of the train on each track is , according to the train's position information, the train's direction of movement and the base station's height, the azimuth between the train and the base station can be obtained According to the Doppler frequency deviation calculation formula: , the Doppler frequency deviation of each train can be calculated and recorded as the first frequency deviation estimate , the set of first frequency offset estimation values ​​is recorded as the first frequency offset set .

[0058] S402, performing time domain frequency offset compensation on the first time domain signal to obtain a second time domain signal.

[0059] Using the first frequency offset estimation set calculated in step S401 The first frequency offset estimate in Perform the first time domain signal (received signal) Perform time domain frequency offset compensation to obtain the second time domain signal ; According to the Fourier transform properties, the frequency deviation is reflected as a phase shift in the time domain. The frequency offset compensation is performed on the time domain signal at the sampling moment, and the second time domain signal after compensation is:

[0060] In the formula is the sampling rate, , Indicates the number of FFT points, is the subcarrier spacing.

[0061] S403, performing time-to-frequency conversion on the second time domain signal to obtain a first frequency domain signal.

[0062] S404: Perform reception processing on the first frequency domain signal to obtain a second frequency offset estimation value and a first signal to interference and noise ratio estimation value.

[0063] For the second time domain signal In the frequency domain, according to the The resource location of the train user is extracted The effective frequency domain data of each train user is then received and processed, including channel estimation, frequency offset estimation, and SINR estimation. The second frequency offset estimation value of the train users , The set composed of At the same time, the obtained The first SINR estimation value of the user.

[0064] S405: Determine whether the absolute value of the second frequency offset estimation value is less than a preset estimation deviation threshold value.

[0065] Set the estimation deviation threshold , according to the second frequency offset set calculated in step S404 The The second frequency offset estimate , for the first frequency offset set The The first frequency offset estimate Make effectiveness judgments.

[0066] If the absolute value of the second frequency offset estimation value is smaller than the preset estimation deviation threshold value, execute S406; otherwise, execute S408.

[0067] S406: The first frequency offset estimation value of the train user is valid, and the second frequency offset estimation value does not flip.

[0068] Among them, if it satisfies , then determine the The first frequency offset estimate of the train users Valid, and the second frequency offset estimate No rollover occurred. For target train users , the first frequency offset estimate To calculate the theoretical Doppler frequency shift, if Valid, train users After the first frequency offset compensation, the residual frequency offset is very small and will not flip, that is, the second frequency offset estimate Smaller, usually smaller than ,and No rollover occurred.

[0069] S407: Perform a frequency domain frequency offset compensation operation on the train user using the first frequency domain signal and the second frequency offset estimation value to obtain a detection result of the train user.

[0070] For train users , using the first frequency domain signal and the second frequency offset set The second frequency offset estimate in , implement frequency domain frequency offset compensation. And further obtain the detection results of the train user.

[0071] S408, performing time-to-frequency conversion on the first time domain signal to obtain a second frequency domain signal.

[0072] If not satisfied , think that The first frequency offset estimate of the train users May not work. A train user uses the first time domain signal to perform time-to-frequency conversion to obtain a second frequency domain signal.

[0073] S409: Perform reception processing on the second frequency domain signal to obtain a second signal to interference plus noise ratio estimation value.

[0074] The second frequency domain signal is received and processed to obtain the first The second SINR estimation value of the train users.

[0075] S410: Determine whether the second signal to interference plus noise ratio estimation value is greater than the first signal to interference plus noise ratio estimation value.

[0076] If the second signal to interference plus noise ratio estimation value is greater than the first signal to interference plus noise ratio estimation value, execute S411; otherwise, return to execute S407, that is, use the first frequency domain signal and the second frequency offset estimation value to perform a frequency domain frequency offset compensation operation on the train user to obtain a detection result of the train user.

[0077] S411, receiving and processing the second frequency domain signal to obtain a detection result of the train user.

[0078] If the second SINR estimate is greater than the first SINR estimate, then it is determined that The first frequency offset estimate of the train users Invalid, for train users The second frequency domain signal is used to implement receiving processing and further obtain the detection result of the train user.

[0079] If the second SINR estimate is less than or equal to the first SINR estimate, it is determined that The first frequency offset estimate of the train users Valid, for train users , using the first frequency domain signal and the second frequency offset set The second frequency offset estimate in , implement frequency domain frequency offset compensation, and further obtain the detection results of the train user.

[0080] Please refer to Figure 5 , Figure 5 The present invention is a flow chart of a frequency deviation processing method based on an access channel. A frequency deviation processing method comprises: S501, calculating a first frequency offset estimation value of each train user to obtain a first frequency offset set.

[0081] Assume that the number of orbits is Assume that the preset movement speed of the train on each track is , according to the train's position information, the train's direction of movement and the base station's height, the azimuth between the train and the base station can be obtained . According to the Doppler frequency deviation calculation formula: , the Doppler frequency deviation of each train can be calculated and recorded as the first frequency deviation estimate , the set of first frequency offset estimation values ​​is recorded as the first frequency offset set .

[0082] S502: Perform time domain frequency offset compensation on the first time domain signal to obtain a second time domain signal.

[0083] Using the first frequency offset estimation set calculated in step S401 The first frequency offset estimate in Perform the first time domain signal (received signal) Perform time domain frequency offset compensation to obtain the second time domain signal ; According to the Fourier transform properties, the frequency deviation is reflected as a phase shift in the time domain. The frequency offset compensation is performed on the time domain signal at the sampling moment, and the second time domain signal after compensation is:

[0084] In the formula is the sampling rate, , Indicates the number of FFT points, is the subcarrier spacing.

[0085] S503: Time-convert the second time domain signal to frequency, extract a valid physical random access channel frequency domain signal in the frequency domain, and receive and process the extracted signal.

[0086] For the second time domain signal After the time conversion, the effective PRACH frequency offset data is extracted according to the PRACH resource position, which is recorded as In the frequency domain, the received PRACH signal Multiply it with the base sequence, then transfer it to the time domain using IDFT to get the result after correlation, recorded as .

[0087] For train users , after step S502, the first frequency offset estimation value is used in the time domain After time domain frequency offset compensation, it is possible to determine the train user The residual frequency deviation in the PRACH is very small, much smaller than the subcarrier spacing of the PRACH. It is determined that the energy of the train user is all concentrated on the main peak, and the energy of the pseudo-correlation peak is very small. Therefore, the sequence Only in The correlation peak is generated at There will be no correlation peak or the correlation peak is very small, such as Figure 6 At this time, PRACH detection only requires the peak value in the main window, and does not require three-window merging or five-window merging. Users detected in the main window are considered valid users.

[0088] Therefore, by using the first frequency offset estimate in the time domain After frequency offset compensation, train users The residual frequency deviation is extremely small, and the energy is almost entirely concentrated in the main peak. The energy of the pseudo-correlation peak is weak. Therefore, PRACH detection only needs to focus on the main window peak, without complex merging calculations (such as three-window merging or five-window merging). This optimization method of the present application simplifies the detection process, reduces computational complexity and resource consumption, and improves detection efficiency and accuracy. It can quickly identify effective users and adapt to the frequency deviation challenges brought by high-speed movement in high-speed rail scenarios.

[0089] The frequency offset processing device provided in the present application is described below. The frequency offset processing device described below and the frequency offset processing method described above can be referenced to each other.

[0090] Please refer to Figure 7 , Figure 7 A frequency offset processing device 700 includes a data channel processing module 710 and an access channel processing module 720 .

[0091] Exemplarily, the data channel processing module 710 is used to calculate the theoretical Doppler frequency offset and form a frequency offset set, and perform a time domain frequency offset compensation operation on the received signal based on the frequency offset set; convert the compensated signal from the time domain to the frequency domain, and perform reception processing to obtain relevant estimated values; based on the validity judgment result of the frequency offset estimate, use different methods to perform frequency domain frequency offset compensation to obtain detection results.

[0092] Exemplarily, the access channel processing module 720 is used to calculate the theoretical Doppler frequency deviation and form a frequency deviation set, and perform a time domain frequency deviation compensation operation on the received signal based on the frequency deviation set; convert the compensated signal from the time domain to the frequency domain, extract the valid signal in the frequency domain, and receive and process the extracted valid signal to obtain the detection result of the access channel.

[0093] Exemplarily, the data channel processing module 710 is further configured to: The theoretical Doppler frequency deviation is calculated according to the train and base station information, and the time domain signal is compensated by using the frequency deviation set to generate a compensated second time domain signal, which specifically includes: The calculating of the theoretical Doppler frequency offset and forming a frequency offset set, and performing a time domain frequency offset compensation operation on the received signal according to the frequency offset set comprises: According to the position information, movement speed, movement direction of the train and the position and height information of the base station, a corresponding theoretical Doppler frequency deviation is calculated for each train user to obtain a first frequency deviation set; Using the frequency offset estimation value in the first frequency offset set and the received first time domain signal, a time domain frequency offset compensation operation is performed on the theoretical Doppler frequency offset corresponding to each train user to obtain a compensated second time domain signal.

[0094] Exemplarily, the data channel processing module 710 is further configured to: The compensated second time domain signal is converted into the frequency domain to obtain a first frequency domain signal, and a new frequency offset and signal to interference noise ratio estimation value are obtained through receiving processing (including channel, frequency offset, and signal to interference noise ratio estimation), specifically including: The converting the compensated signal from the time domain to the frequency domain, receiving and processing the signal, and obtaining the relevant estimated value comprises: Converting the second time domain signal from the time domain to the frequency domain to obtain a first frequency domain signal; The first frequency domain signal is received and processed, and the receiving and processing includes estimating channel characteristics, further estimating frequency offset, and estimating signal to interference and noise ratio, to obtain a new frequency offset estimation value and a first signal to interference and noise ratio estimation value for each train user, and the new frequency offset estimation values ​​constitute a second frequency offset set.

[0095] Exemplarily, the data channel processing module 710 is further configured to: According to the comparison between the new frequency offset estimation value and the threshold value, the frequency domain compensation is performed on the valid value user to obtain the detection result, and the frequency domain is reconverted and processed for the invalid value user, specifically including: If the absolute value of the new frequency offset estimation value of a certain train user is less than the preset estimation deviation threshold value, it is determined that the initial theoretical Doppler frequency offset estimation value of the train user is valid and the new frequency offset estimation value has not been flipped; the frequency domain frequency offset compensation operation is performed on the train user using the first frequency domain signal and the new frequency offset estimation value to obtain the detection result of the train user; If the absolute value of a new frequency deviation estimate of a train user is greater than a preset estimate deviation threshold, the first time domain signal is converted from time domain to frequency domain to obtain a second frequency domain signal, and then the second frequency domain signal is received and processed to obtain a second signal to interference and noise ratio estimate.

[0096] Exemplarily, the data channel processing module 710 is further configured to: According to the comparison result of the second signal to interference and noise ratio estimation value and the first signal to interference and noise ratio estimation value, the validity of the theoretical Doppler frequency offset estimation value is determined, and then the train user detection result is obtained by adopting corresponding operations, specifically including: If the second signal to interference plus noise ratio estimation value is greater than the first signal to interference plus noise ratio estimation value, receiving and processing the second frequency domain signal to obtain a detection result of the train user; If the second signal to interference plus noise ratio estimate value is less than or equal to the first signal to interference plus noise ratio estimate value, it is determined that the initial theoretical Doppler frequency offset estimate value of the train user is valid, and a frequency domain frequency offset compensation operation is performed on the train user using the first frequency domain signal and the new frequency offset estimate value to obtain a detection result of the train user.

[0097] Exemplarily, the data channel processing module 710 is further configured to: The above steps are repeatedly performed to traverse all frequency offset values ​​in the first frequency offset set to complete the processing operation on the data channels of all train users.

[0098] Exemplarily, the access channel processing module 720 is further configured to: The second time domain signal is converted to the frequency domain, the PRACH frequency domain signal is extracted and detected by matched filtering and main window preamble code, the sub-window is not merged, and the main window detection user is a valid user, specifically including: Converting the second time domain signal from the time domain to the frequency domain, and extracting a valid physical random access channel frequency domain signal in the frequency domain; The extracted signal is received and processed, and the receiving and processing includes matched filtering and preamble code detection operations; when performing preamble code detection, only the energy of the main window is used, and no three-window merging or five-window merging operation is performed. The user corresponding to the preamble code detected by the main window is a valid user.

[0099] Exemplarily, the access channel processing module 720 is further configured to: The above steps are repeatedly performed to traverse all frequency offset values ​​in the first frequency offset set to complete the processing operation on the access channels of all train users.

[0100] In some embodiments, the present application further provides a base station, which is used to execute the steps of the frequency offset processing method described in the above embodiments.

[0101] Exemplarily, the specific process of the base station executing the frequency offset processing method is as follows: (1) Calculate the theoretical Doppler frequency offset and perform time domain frequency offset compensation.

[0102] Calculating theoretical Doppler frequency deviation: the base station calculates the corresponding theoretical Doppler frequency deviation for each train user according to the position information, movement speed, movement direction of the train and the position and height information of the base station itself, thereby obtaining a first frequency deviation set.

[0103] Perform a time domain frequency offset compensation operation: use the frequency offset estimation value in the first frequency offset set and the received first time domain signal to perform a time domain frequency offset compensation operation on the theoretical Doppler frequency offset corresponding to each train user to obtain a compensated second time domain signal.

[0104] (2) Convert the compensated signal from time domain to frequency domain and receive it.

[0105] Conversion from time domain to frequency domain: The base station converts the second time domain signal from the time domain to the frequency domain to obtain a first frequency domain signal.

[0106] Receiving and processing: receiving and processing the first frequency domain signal, which includes estimating the channel characteristics, further estimating the frequency offset, and estimating the signal to interference and noise ratio, so as to obtain a new frequency offset estimation value and a first signal to interference and noise ratio estimation value for each train user, and the new frequency offset estimation values ​​constitute a second frequency offset set.

[0107] (3) Perform frequency offset compensation in the frequency domain based on the validity judgment result of the frequency offset estimation value.

[0108] Determine the validity of the frequency deviation estimate: compare the absolute value of a train user's new frequency deviation estimate with the preset estimate deviation threshold.

[0109] If it is less than the threshold value: it is determined that the initial theoretical Doppler frequency offset estimation value of the train user is valid, and the new frequency offset estimation value has not flipped. Then, the first frequency domain signal and the new frequency offset estimation value are used to perform frequency domain frequency offset compensation operation on the train user to obtain the detection result of the train user.

[0110] If it is greater than the threshold value: it is determined that the initial theoretical Doppler frequency offset estimation value of the train user may be invalid. The first time domain signal is converted from the time domain to the frequency domain to obtain a second frequency domain signal, and then the second frequency domain signal is received and processed to obtain a second signal to interference and noise ratio estimation value.

[0111] (4) Determine and obtain the detection result based on the estimated value of the signal-to-interference-noise ratio.

[0112] Comparing the signal to interference plus noise ratio estimation value: comparing the second signal to interference plus noise ratio estimation value with the first signal to interference plus noise ratio estimation value.

[0113] If the second signal to interference plus noise ratio estimation value is greater than the first signal to interference plus noise ratio estimation value: it is determined that the initial theoretical Doppler frequency offset estimation value of the train user may be invalid, and the second frequency domain signal is received and processed to obtain the detection result of the train user.

[0114] If the second signal to interference and noise ratio estimate value is less than or equal to the first signal to interference and noise ratio estimate value: determine that the initial theoretical Doppler frequency offset estimate value of the train user is valid, and use the first frequency domain signal and the new frequency offset estimate value to perform a frequency domain frequency offset compensation operation on the train user to obtain a detection result of the train user.

[0115] (5) Extract the frequency domain signal of the physical random access channel and obtain the detection result of the access channel.

[0116] Extracting the frequency domain signal: converting the second time domain signal from the time domain to the frequency domain, and extracting the effective physical random access channel frequency domain signal in the frequency domain.

[0117] Get the detection result of the access channel: receive and process the extracted signal, including matched filtering and preamble detection. When performing preamble detection, only the energy of the main window is used, and three-window merging or five-window merging is not performed. The user corresponding to the preamble detected by the main window is the valid user.

[0118] Therefore, the base station provided in the present application has the following advantages by fine-tuning the frequency offset problem in high-speed mobile scenarios: first, the base station can accurately calculate and compensate for the frequency offset to ensure the accuracy and reliability of the signal; second, through the conversion from the time domain to the frequency domain and the reception processing, it can effectively extract and process the frequency domain signal of the physical random access channel, simplify the detection process, and improve the detection efficiency; finally, according to the judgment of the frequency offset estimation value and the signal-to-interference-noise ratio estimation value, the frequency domain frequency offset compensation strategy is flexibly adjusted to ensure that accurate detection results can be obtained under different conditions, thereby comprehensively improving the communication quality in high-speed mobile scenarios.

[0119] It should be noted here that the above-mentioned device and base station provided in the embodiments of the present application can implement all the method steps implemented in the above-mentioned method embodiments, and can achieve the same technical effects. The parts and beneficial effects that are the same as those in the method embodiments will not be described in detail here.

[0120] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations 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 deviation processing method, characterized in that: The method comprises: For data channels: calculate the theoretical Doppler frequency offset and form a frequency offset set, and perform time domain frequency offset compensation on the received signal based on the frequency offset set; convert the compensated signal from the time domain to the frequency domain, and perform reception processing to obtain relevant estimated values; according to the validity judgment result of the frequency offset estimate, use different methods to perform frequency domain frequency offset compensation to obtain the detection result; For the access channel: calculate the theoretical Doppler frequency offset and form a frequency offset set, and perform time domain frequency offset compensation on the received signal based on the frequency offset set; convert the compensated signal from the time domain to the frequency domain, extract the valid signal in the frequency domain, and receive and process the extracted valid signal to obtain the detection result of the access channel.

2. The frequency deviation processing method according to claim 1, characterized in that: The calculating of the theoretical Doppler frequency offset and forming a frequency offset set, and performing a time domain frequency offset compensation operation on the received signal according to the frequency offset set comprises: According to the position information, movement speed, movement direction of the train and the position and height information of the base station, a corresponding theoretical Doppler frequency deviation is calculated for each train user to obtain a first frequency deviation set; Using the frequency offset estimation value in the first frequency offset set and the received first time domain signal, a time domain frequency offset compensation operation is performed on the theoretical Doppler frequency offset corresponding to each train user to obtain a compensated second time domain signal.

3. The frequency deviation processing method according to claim 2, characterized in that: The converting the compensated signal from the time domain to the frequency domain, receiving and processing the signal, and obtaining the relevant estimated value comprises: Converting the second time domain signal from the time domain to the frequency domain to obtain a first frequency domain signal; The first frequency domain signal is received and processed, and the receiving and processing includes estimating channel characteristics, further estimating frequency offset, and estimating signal to interference and noise ratio, to obtain a new frequency offset estimation value and a first signal to interference and noise ratio estimation value for each train user, and the new frequency offset estimation values ​​constitute a second frequency offset set.

4. The frequency deviation processing method according to claim 3, characterized in that: The method of performing frequency offset compensation in the frequency domain in different ways according to the validity judgment result of the frequency offset estimation value to obtain the detection result includes: If the absolute value of the new frequency offset estimation value of a certain train user is less than the preset estimation deviation threshold value, it is determined that the initial theoretical Doppler frequency offset estimation value of the train user is valid and the new frequency offset estimation value has not been flipped; the frequency domain frequency offset compensation operation is performed on the train user using the first frequency domain signal and the new frequency offset estimation value to obtain the detection result of the train user; If the absolute value of a new frequency deviation estimate of a train user is greater than a preset estimate deviation threshold, the first time domain signal is converted from time domain to frequency domain to obtain a second frequency domain signal, and then the second frequency domain signal is received and processed to obtain a second signal to interference and noise ratio estimate.

5. The frequency deviation processing method according to claim 4, characterized in that: The method further comprises: If the second signal to interference plus noise ratio estimation value is greater than the first signal to interference plus noise ratio estimation value, receiving and processing the second frequency domain signal to obtain a detection result of the train user; If the second signal to interference plus noise ratio estimate value is less than or equal to the first signal to interference plus noise ratio estimate value, it is determined that the initial theoretical Doppler frequency offset estimate value of the train user is valid, and a frequency domain frequency offset compensation operation is performed on the train user using the first frequency domain signal and the new frequency offset estimate value to obtain a detection result of the train user.

6. The frequency deviation processing method according to claim 2, characterized in that: The step of converting the compensated signal from the time domain to the frequency domain, extracting a valid signal in the frequency domain, and receiving and processing the extracted valid signal to obtain a detection result of the access channel includes: Converting the second time domain signal from the time domain to the frequency domain, and extracting a valid physical random access channel frequency domain signal in the frequency domain; The extracted signal is received and processed, and the receiving and processing includes matched filtering and preamble code detection operations; when performing preamble code detection, only the energy of the main window is used, and no three-window merging or five-window merging operation is performed. The user corresponding to the preamble code detected by the main window is a valid user.

7. The frequency deviation processing method according to claim 5, characterized in that: The method further comprises: Repeat the steps of claim 3 to claim 5 to traverse all frequency offset values ​​in the first frequency offset set to complete the processing operation on the data channels of all train users.

8. The frequency deviation processing method according to claim 6, characterized in that: The method further comprises: Repeat the steps of claim 6 to traverse all frequency offset values ​​in the first frequency offset set to complete the processing operation of the access channels of all train users.

9. A frequency deviation processing device, characterized in that: The device comprises: The data channel processing module is used to calculate the theoretical Doppler frequency offset and form a frequency offset set, and perform a time domain frequency offset compensation operation on the received signal according to the frequency offset set; convert the compensated signal from the time domain to the frequency domain, and perform receiving processing to obtain a related estimated value; according to the validity judgment result of the frequency offset estimated value, use different methods to perform frequency domain frequency offset compensation to obtain a detection result; The access channel processing module is used to calculate the theoretical Doppler frequency deviation and form a frequency deviation set, and perform time domain frequency deviation compensation operation on the received signal according to the frequency deviation set; convert the compensated signal from the time domain to the frequency domain, extract the effective signal in the frequency domain, and receive and process the extracted effective signal to obtain the detection result of the access channel.

10. A base station, characterized in that: The base station is used to execute the steps of the frequency offset processing method according to any one of claims 1 to 8.

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