A dynamic channel modeling method based on external field data collection

Abstract

The application relates to a dynamic channel modeling method based on external field data collection, and belongs to the technical field of channel modeling. The application provides a dynamic channel modeling method based on external field collected data. The method is to integrate dynamic external field data into the channel modeling system of 3GPP-38901, and to control the baseband sampling rate based on a half-wavelength sampling density, so that accurate channel modeling of external field collected data, such as power, time delay, Doppler, cross-polarization ratio, antenna directional diagram and angle information, etc. is realized, and the modeling application range of 3GPP-38901 is greatly expanded and enriched.

Description

Technical Field

[0001] This invention belongs to the field of channel modeling technology, specifically relating to a dynamic channel modeling method based on field data acquisition. Background Technology

[0002] The channel modeling method in the 3GPP-38901 protocol can calculate the angular relationship between the transmitter and receiver based on their position information and perform channel modeling according to the standard channel model provided by the protocol. For the angular information between the transmitter and receiver, the common practice is to use mathematical methods to establish the relative trajectory information (position information) between them for calculation. Although the above method can accurately calculate the channel impulse response, it cannot fully describe the channel characteristics in the field, mainly in the following aspects: First, the relative motion trajectory of the transmitter and receiver in the field has some randomness, leading to errors in the mathematically modeled trajectory; Second, due to external environmental interference and the time-varying characteristics of the wireless channel, there are differences between the standard channel model and the actual field channel. The traditional approach is to control the data collected in the field separately through the digital domain, but this implementation process is outside the channel modeling system.

[0003] According to the 3GPP-38901 protocol, the traditional geometry-based modeling formula is as follows:

[0004]

[0005] in Indicates a non-direct line of sight. Indicates the direct line of sight, K R The Rice K-factor represents the proportion of the LOS (Left-of-Sight) path among all paths. Each non-direct-view path is composed of 20 sub-paths. and The modeling method is as follows:

[0006]

[0007]

[0008] in:

[0009] u represents the antenna index of the receiving antenna;

[0010] 's' represents the antenna index of the transmitting antenna;

[0011] n represents the cluster index;

[0012] m represents the sub-path index;

[0013] P n This represents the normalized cluster power;

[0014] M represents the number of sub-diameters;

[0015] θ represents the pitch angle;

[0016] Indicates azimuth angle

[0017] F rx,u,θ This indicates the radiation pattern in the vertical direction of the receiving antenna;

[0018] This shows the radiation pattern of the receiving antenna in the horizontal direction;

[0019] κ represents the cross-polarization ratio;

[0020] Φ represents the random phase;

[0021] This represents the coordinates of the receiving terminal in a spherical coordinate system;

[0022] This represents the coordinates of the transmitting base station in a spherical coordinate system;

[0023] Represents the coordinate vector of the u-th receiving antenna;

[0024] This represents the coordinate vector of the s-th transmitting antenna;

[0025] λ0 represents the wavelength;

[0026] v represents the velocity vector of the terminal;

[0027] Assuming the half-wavelength sampling density is ρ, representing the number of sampling points over half a wavelength during modeling, and the interval between two sampling points is... λ represents the wavelength, as shown in the figure below. Assume the terminal moves from point a to point b, and its propagation delay is... Transform into Where c represents the speed of light, the propagation delay is controlled by the wireless channel simulator hardware through delay control of the input signal, and the channel modeling algorithm does not involve delay control.

[0028] According to the Doppler formula:

[0029]

[0030] Among them, f center Here, is the center frequency, v represents the terminal's operating speed, and cosθ is the angle of arrival, determined based on the geometric relationship between the transmitting and receiving ends. According to... t0 represents the sampling time between two sample points. Substituting v into formula (4) yields...

[0031]

[0032] make Let the baseband sampling rate be represented, then formula (5) can be expressed as:

[0033]

[0034] in This represents the maximum Doppler frequency shift. When the terminal velocity v is constant, f d,max It is a definite value. Formula (6) shows that as long as the wireless channel simulator strictly controls t0 and calculates the spatial angle θ in real time according to the geometric relationship (which can be represented by the azimuth and elevation angles), it can achieve the control of the Doppler frequency shift. At the same time, the angle information imported from the external field can be substituted into formula (2) or (3) to calculate the antenna pattern (F). tx and F rx Cross-polarization ratio matrix (NLOS scenario), the projection of the diameter onto the antenna panel ( and The impact of the channel impulse response is investigated, thereby simulating the wireless channel.

[0035] Therefore, at this stage, it is necessary to design a dynamic channel modeling method based on field data acquisition to solve the above problems. Summary of the Invention

[0036] The purpose of this invention is to provide a dynamic channel modeling method based on field data acquisition, which solves the technical problems existing in the prior art.

[0037] To achieve the above objectives, the technical solution of the present invention is as follows:

[0038] A dynamic channel modeling method based on field data acquisition is proposed. The field data is path-based, and the relevant parameters of all paths are updated once at each sampling point. These relevant parameters include the departure angle, arrival angle, cross-polarization ratio, Doppler frequency offset, K-factor, multipath power, and delay for each path. Channel modeling is completed using the 3GPP-38901 protocol modeling framework according to the following steps:

[0039] S1 reads the data information of all samples from all paths, iterates through the Doppler frequency offsets of all paths, and finds the maximum Doppler frequency offset f. d,max ;

[0040] S2 determines the appropriate half-wavelength sampling density ρ, and calculates the baseband sampling rate F according to formula (6). s ;

[0041] S3 updates the sampling time t based on the data collected from the field. u Determine the interpolation factor N u =F s t uIf N u <2, by adjusting the value of ρ to make N u ≥2 and is a positive integer;

[0042] S4 performs N on all parameters of the diameter. u Interpolation;

[0043] S5 inputs the departure angle of the field acquisition into the transmit antenna pattern and the arrival angle of the field acquisition into the receive antenna pattern, and calculates the projection of each end onto the antenna panel based on the angle information of the transmit and receive ends.

[0044] S6 performs channel modeling based on the K factor using formula (1);

[0045] S7 Let formula (8) but

[0046]

[0047] Furthermore, in step S1, the maximum Doppler frequency shift Ignore symbols.

[0048] Furthermore, in step S2, the half-wavelength sampling density ρ is set to 4-8.

[0049] Furthermore, in step S3, the half-wavelength sampling density ρ is a natural number greater than 1.

[0050] Furthermore, in step S6, according to the formula

[0051]

[0052]

[0053] Where θ ZOA and φ AOA θ represents the angle information at the receiving end. v and The position information of the terminal is represented, v′ represents the instantaneous scalar velocity value of the terminal, and formula (7) can be expressed as:

[0054]

[0055] in, According to step S1, we can obtain formula (8)

[0056]

[0057] Therefore, for data collected in the field make

[0058]

[0059] Then k = [k1 k2 … 1 …] ∈ [0 1], N represents the number of imported field data after interpolation.

[0060] Furthermore, if the field data acquisition is based on sample points, only power P and phase are considered. Delay and Doppler information f d Large-scale fading needs to be incorporated into the modeling formula through mathematical transformations.

[0061] Assuming the collected data is from a LOS scenario, the final result of its modeling is a change in the amplitude and phase of the input signal. Therefore, formula (3) can be rewritten as follows:

[0062]

[0063] For the imported field data, channel modeling can be completed using the 3GPP-38901 protocol modeling framework by following these steps:

[0064] S11 reads the data information of all sample points, traverses the Doppler frequency offset of all paths, and finds the maximum Doppler frequency offset.

[0065] S12 determines the half-wavelength sampling density ρ, and the baseband sampling rate F is calculated according to formula (6). s ;

[0066] S13 updates the sampling time t based on the field data collection data. u Determine the interpolation factor N u =F s t u If N u <2, N can be adjusted by changing the value of ρ. u ≥2 and is a positive integer;

[0067] S14 performs N on all parameters of the diameter. u Interpolation;

[0068] S15 Let A = 10 0.1×P ,

[0069] For LOS scenarios, S16 is based on the formula.

[0070]

[0071]

[0072] Where θ LOS,ZOA and φ LOS,AOA Represents the angle information at the receiving end; θ v and The position information of the terminal is represented, v′ represents the instantaneous scalar velocity value of the terminal, and formula (10) can be expressed as:

[0073]

[0074] in, Based on step (1), we can obtain formula (11)

[0075]

[0076] Therefore, for data collected in the field make

[0077]

[0078] Then k = [k1 k2 … 1 …] ∈ [0 1], N represents the number of imported field data after interpolation;

[0079] S17 Let formula (11) in but

[0080]

[0081] At this point, all terms in the 3GPP-38901 modeling formula can be derived from power P and phase data collected in the field. Delay and Doppler information f d Generate.

[0082] A dynamic channel modeling system based on field data acquisition is provided, which uses the dynamic channel modeling method based on field data acquisition described above for dynamic channel modeling.

[0083] A computer storage medium storing a computer program, which, when run, executes a dynamic channel modeling method based on field data acquisition as described above.

[0084] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0085] One of the beneficial effects of this solution is that it proposes a dynamic channel modeling method based on field-acquired data. This method incorporates dynamic field data into the 3GPP-38901 channel modeling system and controls the baseband sampling rate based on half-wavelength sampling density. This enables accurate channel modeling of some field-acquired data, such as power, delay, Doppler, cross-polarization ratio, antenna pattern, and angle information, greatly expanding and enriching the modeling applicability of 3GPP-38901. Attached Figure Description

[0086] Figure 1 This is a schematic diagram of trajectory sampling points in an embodiment of this application.

[0087] Figure 2 A schematic diagram of the impact response (first path) generated by importing external data into the model for an embodiment of this application.

[0088] Figure 3 This is a schematic diagram of power loss information (positive value, representing loss data) of externally imported data in an embodiment of this application.

[0089] Figure 4 This is a schematic diagram illustrating the latency information of externally imported data in an embodiment of this application.

[0090] Figure 5 This is a schematic diagram of Doppler information for externally imported data in an embodiment of this application.

[0091] Figure 6 This is a schematic diagram of the time-domain channel impulse response of externally imported data in an embodiment of this application.

[0092] Figure 7 This is a schematic diagram of the frequency domain impulse response of a portion of the data segment after modeling based on externally imported data, according to an embodiment of this application. Detailed Implementation

[0093] The following description, in conjunction with the appendix of the present invention, Figure 1 -Appendix Figure 7 The technical solutions in the embodiments of the present invention are clearly and completely described herein. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0094] The channel modeling method in the 3GPP-38901 protocol can calculate the angular relationship between the transmitter and receiver based on their position information and perform channel modeling according to the standard channel model provided by the protocol. For the angular information between the transmitter and receiver, the common practice is to use mathematical methods to establish the relative trajectory information (position information) between them for calculation. Although the above method can accurately calculate the channel impulse response, it cannot fully describe the channel characteristics in the field, mainly in the following aspects: First, the relative motion trajectory of the transmitter and receiver in the field has some randomness, leading to errors in the mathematically modeled trajectory; Second, due to external environmental interference and the time-varying characteristics of the wireless channel, there are differences between the standard channel model and the actual field channel. The traditional approach is to control the data collected in the field separately through the digital domain, but this implementation process is outside the channel modeling system.

[0095] According to the 3GPP-38901 protocol, the traditional geometry-based modeling formula is as follows:

[0096]

[0097] in Indicates a non-direct line of sight. Indicates the direct line of sight, K R The Rice K-factor represents the proportion of the LOS (Left-of-Sight) path among all paths. Each non-direct-view path is composed of 20 sub-paths. and The modeling method is as follows:

[0098]

[0099]

[0100] in:

[0101] u represents the antenna index of the receiving antenna;

[0102] 's' represents the antenna index of the transmitting antenna;

[0103] n represents the cluster index;

[0104] m represents the sub-path index;

[0105] P n This represents the normalized cluster power;

[0106] M represents the number of sub-diameters;

[0107] θ represents the pitch angle;

[0108] Indicates azimuth angle

[0109] F rx,u,θ This indicates the radiation pattern in the vertical direction of the receiving antenna;

[0110] This shows the radiation pattern of the receiving antenna in the horizontal direction;

[0111] κ represents the cross-polarization ratio;

[0112] Φ represents the random phase;

[0113] This represents the coordinates of the receiving terminal in a spherical coordinate system;

[0114] This represents the coordinates of the transmitting base station in a spherical coordinate system;

[0115] Represents the coordinate vector of the u-th receiving antenna;

[0116] This represents the coordinate vector of the s-th transmitting antenna;

[0117] λ0 represents the wavelength;

[0118] v represents the velocity vector of the terminal;

[0119] Assuming the half-wavelength sampling density is ρ, representing the number of sampling points over half a wavelength during modeling, and the interval between two sampling points is... λ represents wavelength, such as Figure 1 As shown. Assume the terminal moves from point a to point b, and its propagation delay is... Transform into Where c represents the speed of light, the propagation delay is controlled by the wireless channel simulator hardware through delay control of the input signal, and the channel modeling algorithm does not involve delay control.

[0120] According to the Doppler formula:

[0121]

[0122] Among them, f center Here, is the center frequency, v represents the terminal's operating speed, and cosθ is the angle of arrival, determined based on the geometric relationship between the transmitting and receiving ends. According to... t0 represents the sampling time between two sample points. Substituting v into formula (4) yields...

[0123]

[0124] make Let the baseband sampling rate be represented, then formula (5) can be expressed as:

[0125]

[0126] in This represents the maximum Doppler frequency shift. When the terminal velocity v is constant, f d,max It is a definite value. Formula (6) shows that as long as the wireless channel simulator strictly controls t0 and calculates the spatial angle θ in real time according to the geometric relationship (which can be represented by the azimuth and elevation angles), it can achieve the control of the Doppler frequency shift. At the same time, the angle information imported from the external field can be substituted into formula (2) or (3) to calculate the antenna pattern (F). tx and F rx Cross-polarization ratio matrix (NLOS scenario), the projection of the diameter onto the antenna panel ( and The impact of the channel impulse response is investigated, thereby simulating the wireless channel.

[0127] If the field data acquisition is based on paths, and the relevant parameters of all paths are updated once at each sampling point, including the departure angle, arrival angle, cross-polarization ratio, Doppler frequency offset, K-factor (used to distinguish between LOS and NLOS scenarios), multipath power, and delay for each path, channel modeling can be completed using the 3GPP-38901 protocol modeling system as follows:

[0128] 1) Read the data information of all samples of all paths, traverse the Doppler frequency offset of all paths and find the maximum Doppler frequency offset. (Ignoring symbols);

[0129] 2) Determine a suitable half-wavelength sampling density ρ (generally taken as 4 to 8), and calculate the baseband sampling rate F according to formula (6). s ;

[0130] 3) Update the sampling time t based on the field data collection data. u Determine the interpolation factor N u =F s t u If N u <2, N can be adjusted by changing the value of ρ (which can be a natural number greater than 1). u ≥2 and is a positive integer;

[0131] 4) Perform N-tests on all parameters of the diameter. u Interpolation;

[0132] 5) Input the departure angle of the field acquisition into the transmitting antenna pattern, and input the arrival angle of the field acquisition into the receiving antenna pattern. Calculate the projection of each end onto the antenna panel based on the angle information of the transmitting and receiving ends.

[0133] 6) Channel modeling is performed using formula (1) based on the K factor. For formula (2) or formula (3), the only part that cannot be directly calculated is...

[0134]

[0135] According to the formula

[0136]

[0137]

[0138] Where θ ZOA and φ AOA This represents the angle information at the receiving end, which is included in the data collected in the field. θ v and v' represents the terminal's location information, and v′ represents the instantaneous scalar velocity value of the terminal. The imported data from the external field does not contain location information; however, formula (7) can be expressed as...

[0139]

[0140] in, Based on step (1), we can obtain formula (8)

[0141]

[0142] Therefore, for data collected in the field make

[0143]

[0144] Then k = [k1 k2 … 1 …] ∈ [0 1], N represents the number of imported field data after interpolation.

[0145] 7) Let the formula (8) but

[0146]

[0147] At this point, all terms in the 3GPP-38901 modeling formula can be generated using imported field data. Figure 2 This is the channel impulse response of the first path generated by importing external data into the model. As can be seen from the middle part of the data, the channel has undergone a scene switch.

[0148] If the field data acquisition is based on sample points, and only power P (in dB, path loss) and phase are available... Delay and Doppler information f d Since the collected data only contains path loss and lacks multipath power information, large-scale fading needs to be incorporated into the modeling formula through mathematical transformation.

[0149] Assuming the collected data is from a LOS scenario (NLOS scenarios can be analyzed by analogy), regardless of the modeling process, the final result of the modeling is a change in the amplitude and phase of the input signal. Therefore, formula (3) can be rewritten as follows:

[0150]

[0151] For the imported field data, channel modeling can be completed using the 3GPP-38901 protocol modeling framework by following these steps:

[0152] 1) Read the data information of all sample points, traverse the Doppler frequency offset of all paths and find the maximum Doppler frequency offset.

[0153] 2) Determine a suitable half-wavelength sampling density ρ (generally taken as 4 to 8), and calculate the baseband sampling rate F according to formula (6).s ;

[0154] 3) Update the sampling time t based on the field data collection data. u Determine the interpolation factor N u =F s t u If N u <2, N can be adjusted by changing the value of ρ (which can be a natural number greater than 1). u ≥2 and is a positive integer;

[0155] 4) Perform N-tests on all parameters of the diameter. u Interpolation;

[0156] 5) Let A = 10 0.1×P ,

[0157] 6) For LOS scenarios, the only part of formula (2) that cannot be directly calculated is

[0158]

[0159] According to the formula

[0160]

[0161]

[0162] Where θ LOS,ZOA and φ LOS,AOA This represents the angle information at the receiving end. θ v and v′ represents the terminal's location information, and v′ represents the instantaneous scalar velocity value of the terminal. The imported data from the external field does not contain location information; however, formula (10) can be expressed as...

[0163]

[0164] in,

[0165]

[0166] Based on step (1), we can obtain formula (11)

[0167]

[0168] Therefore, for data collected in the field make

[0169]

[0170] Then k = [k1 k2 … 1 …] ∈ [0 1], N represents the number of imported field data after interpolation.

[0171] 7) Let the formula (11) but

[0172]

[0173] At this point, all terms in the 3GPP-38901 modeling formula can be derived from the power P (in dB, path loss) and phase parameters obtained from field sampling. Delay and Doppler information f d Generate.

[0174] Figure 3-5 It consists of partial power delay and Doppler information collected during vehicle operation.

[0175] Using the method described in this scheme, the channel impulse response generated by modeling is obtained from the above data, such as... Figure 6 As shown.

[0176] Analysis of the Doppler data acquired in the field revealed a frequency offset of approximately -137Hz between 12,000 and 16,000 sampling points. A Fourier transform of the modeled channel impulse response showed that the impulse response contained frequency offset information. Figure 7 As shown.

[0177] The above are preferred embodiments of the present invention. Any changes made to the technical solution of the present invention that do not exceed the scope of the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. A dynamic channel modeling method based on field data acquisition, characterized in that, The field acquisition data is based on paths, and the relevant parameters of all paths are updated once at each sampling point; the relevant parameters include the departure angle, arrival angle, cross-polarization ratio, Doppler frequency shift, K-factor, multipath power and time delay of each path; Complete channel modeling using the 3GPP-38901 protocol modeling architecture by following these steps: S1 reads the data information of all samples from all paths, iterates through the Doppler frequency shifts of all paths, and finds the maximum Doppler frequency shift. ; S2 Determine the appropriate half-wavelength sampling density According to formula (6) Calculate baseband sampling rate ; in, The maximum Doppler frequency shift is represented by θ; θ represents the pitch angle. For Doppler frequency shift; S3 Updates the sampling time based on the field data collection data. Determine the interpolation factor ,if By adjusting The value of makes And it is a positive integer; S4 performs all parameters of the diameter Interpolation; S5 inputs the departure angle of the field acquisition into the transmit antenna pattern and the arrival angle of the field acquisition into the receive antenna pattern, and calculates the projection of each end onto the antenna panel based on the angle information of the transmit and receive ends. S6. Based on the K factor, use formula (1) Perform channel modeling; in, Indicates a non-direct line of sight. Indicates the direct line of sight. Rice's K-factor; S7 Let formula (8) In ,but ； in, The maximum Doppler frequency shift is given by j, where j is the imaginary unit. Indicates wavelength.

2. The dynamic channel modeling method based on field data acquisition as described in claim 1, characterized in that, In step S1, the maximum Doppler frequency shift Ignore symbols.

3. The dynamic channel modeling method based on field data acquisition as described in claim 1, characterized in that, In step S2, half-wavelength sampling density Take 4-8.

4. The dynamic channel modeling method based on field data acquisition as described in claim 1, characterized in that, In step S3, the half-wavelength sampling density Take a natural number greater than 1.

5. The dynamic channel modeling method based on field data acquisition as described in claim 1, characterized in that, In step S6, according to the formula in and This indicates the angle information at the receiving end. and This indicates the location information of the terminal. The instantaneous scalar velocity value of the terminal is represented by formula (7). Represented as （8） in, This represents the coordinates of the receiving terminal in a spherical coordinate system; According to step S1, we obtain formula (8) Therefore, for data collected in the field ,make but , , This indicates the number of imported field data after interpolation.

6. The dynamic channel modeling method based on field data acquisition as described in claim 5, characterized in that, If the field data collection is based on sample points, only power... Phase Time delay and Doppler shift Large-scale fading needs to be incorporated into the modeling formula through mathematical transformations. Assuming the collected data is from a LOS scenario, the final result of its modeling is to bring about changes in the amplitude and phase of the input signal, therefore formula (3) Rewritten （9） in, This represents the channel impulse response in a LOS scenario; θ represents the pitch angle. This indicates the vertical electric field component pattern of the receiving antenna; This represents the radiation pattern of the horizontal electric field component of the receiving antenna; Indicates the first u The coordinate vector of the root receiving antenna; Indicates the first s The coordinate vector of the root transmitting antenna; For the imported field data, follow these steps to complete channel modeling using the 3GPP-38901 protocol modeling framework: S11 reads the data information of all sample points, traverses the Doppler frequency shift of all paths, and finds the maximum Doppler frequency shift. ; S12 Determine half-wavelength sampling density According to formula (6) Calculate baseband sampling rate ; S13 Update time based on sample points of field-collected data Determine the interpolation factor ,if By adjusting The value of makes And it is a positive integer; S14 Perform all parameters of the diameter Interpolation; S15 Order , ; S16 For LOS scenarios, according to the formula in and This indicates the angle information at the receiving end; and This indicates the location information of the terminal. The instantaneous scalar velocity value of the terminal is represented by formula (10). Represented as （11） in, Based on step (1), we obtain formula (11) Therefore, for data collected in the field ,make but , , This indicates the number of imported field data after interpolation; S17 Let the formula (11) in ,but At this point, all terms in the 3GPP-38901 modeling formula have been derived from power data collected in the field. Phase Time delay and Doppler shift Generate.

7. A dynamic channel modeling system based on field data acquisition, characterized in that, Dynamic channel modeling is performed using a dynamic channel modeling method based on field data acquisition as described in any one of claims 1-6.

8. A computer storage medium, characterized in that, The storage medium stores a computer program, which, when run, executes a dynamic channel modeling method based on field data acquisition as described in any one of claims 1-6.

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