Method, device and storage medium for estimating maximum delay spread in wireless ad hoc network

Abstract

The present invention relates to the field of wireless communication technologies, and particularly to a method, device, and storage medium for estimating the maximum delay spread in a wireless ad hoc network. In the method for estimating the maximum delay spread in the wireless ad hoc network, after receiving the signal r, first calculate the product h of the pilot position signal and the conjugate of the reference symbol, then calculate the frequency-domain correlation Corr, and the product f(m) of the frequency-domain correlation and the filtering coefficient. Post-process the product f(m) and select the gear of the maximum delay spread. The method for estimating the maximum delay spread in the wireless ad hoc network provides an algorithm for estimating the maximum delay spread for the main application scenarios and pilot patterns of the wireless ad hoc network, and can clearly divide the delay spread regions in different scenarios, and then estimate the maximum delay spread of the channel.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technologies, and particularly relates to a method, device, and storage medium for estimating the maximum delay spread in a wireless ad hoc network. Background Art

[0002] A wireless ad hoc network is a new type of network form. It breaks through the geographical limitations of traditional wireless cellular networks, can achieve rapid network formation without relying on any communication infrastructure, and relies on the mutual cooperation between wireless terminals to complete network establishment, maintenance, and information transmission. It can be deployed more quickly, conveniently, and efficiently, and is especially suitable for the communication requirements in certain emergency situations.

[0003] Channel estimation, as one of the key technologies in the field of wireless communication, is widely used in communication scenarios such as 3G / LTE / NR. The signal received by a wireless receiver arrives at the receiver through different direct, reflected, refracted, etc. paths. Since the distances of the signals passing through each path are different, the arrival times of the received signals in each path are different, resulting in multipath delay spread. The time difference between the first and the last clearly distinguishable paths is considered the maximum delay spread, as Figure 1 shown.

[0004] Classifying common wireless channels, the corresponding maximum delay spread lengths can be divided into 1 / 4 CP length, 1 / 2 CP length, and 1 CP length. By filtering the PDP spectrum of the received signal using three filters corresponding to the three lengths, a most matching filter can be selected, and the length corresponding to it is the maximum delay spread to be estimated.

[0005] The LMMSE channel estimation algorithm based on the maximum delay spread also has a large number of applications and optimization schemes in the algorithms of various wireless receiving devices. Estimating the maximum delay spread by designing a suitable filter to divide the time domain length of the received signal PDP is a scheme with relatively high accuracy and low complexity.

[0006] In a wireless ad hoc network, if more accurate channel estimation is to be achieved, a relatively high requirement is also put forward for the accuracy of the algorithm for estimating the maximum delay spread. However, due to the main application scenarios of the wireless ad hoc network and the pilot pattern design of the wireless ad hoc network being different from those of wireless public networks such as 3G / LTE / NR, the algorithm for estimating the maximum delay spread in the wireless ad hoc network also needs to be redesigned.

[0007] To solve the above problems, the present invention proposes a method for estimating the maximum delay spread in a wireless ad hoc network. Summary of the Invention

[0008] To make up for the deficiencies of the prior art, the present invention provides a simple and efficient method for estimating the maximum delay spread in a wireless ad hoc network.

[0009] The present invention is implemented through the following technical solutions:

[0010] A method for estimating the maximum delay spread in a wireless ad hoc network, characterized by comprising the following steps:

[0011] Step S1, receiving the signal r;

[0012] Step S2, calculating the frequency-domain channel response h, that is, the conjugate product of the signal at the pilot position and the reference symbol;

[0013] In the said step S2, the calculation process is as follows:

[0014] Step S2.1, extracting the signal value r j at the pilot position p pj ;

[0015] Step S2.2, calculating the conjugate complex number j of the reference symbol s ;

[0016] Step S2.3, calculating the frequency-domain channel response h j , and the calculation formula is as follows:

[0017] ,

[0018] Step S2.4, summarizing the product results at all pilot positions into a vector h;

[0019] ,

[0020] where v is the total number of positions of the known pilot symbols.

[0021] Step S3, calculating the frequency-domain correlation Corr(i) at the i-th point, and the calculation formula is as follows:

[0022] ,

[0023] where is the number of pilots on each reference symbol, h(k) is the frequency-domain channel response of the k-th point of the pilot symbol, is the conjugate of the frequency-domain channel response of the k + i-th point of the pilot symbol , and L is the minimum frequency-domain correlation length required to restore the PDP shape;

[0024] In the said step S3, according to the simulation results, the minimum frequency-domain correlation length L required to restore the PDP shape is 72;

[0025] ;

[0026] Among them, Nlag represents the number of points of frequency-domain correlation, and delta represents the correlation interval;

[0027] To reduce the computational complexity, the delta value is customarily selected as 2, and the Nlag value is 36. That is, Corr(0), Corr(2), Corr(4),..., Corr(70) need to be calculated. Therefore, in the calculation formula of the frequency-domain correlation Corr(i), .

[0028] In step S3, since the frequency-domain correlation of different symbols changes slowly on the same transceiver antenna pair, the alpha filter is used to update the value of the signal based on the weighted average of the current value and the historical value;

[0029] For the same symbol, the PDP spectra are different on different transceiver antenna pairs. Therefore, the corresponding frequency-domain correlations are not suitable for merging or averaging processing; for a 2-transmitter 2-receiver system, calculate the frequency-domain correlations on its different antenna pairs, that is:

[0030] ,

[0031] where iRx is the index of the receiver Receiver, and iTx is the index of the transmitter Transmitter.

[0032] Step S4: Calculate the product of the frequency-domain correlation and the filter coefficient , and the calculation formula is as follows:

[0033] ,

[0034] where, are three groups of filter coefficients corresponding to three types of filters;

[0035] The maximum delay spread lengths corresponding to the filters are 1 / 4 of the cyclic prefix CP length, 1 / 2 of the cyclic prefix CP length, and 1 cyclic prefix CP length respectively.

[0036] Step S5: Post-process the product f and select the gear with the maximum delay spread, specifically as follows:

[0037] Use to perform normalization to obtain the parameters and , that is

[0038] ,

[0039] If both parameter x and parameter y are greater than 0.92, set parameter idxRegion to 1. The maximum delay spread is one quarter of the cyclic prefix CP, and the maximum delay spread length corresponding to the filter is 1 / 4 of the cyclic prefix CP length;

[0040] If parameter x is not greater than 0.92 but parameter y is greater than 0.92, set parameter idxRegion to 2, indicating that the maximum delay spread is half of the cyclic prefix CP, and the maximum delay spread length corresponding to the filter is 1 / 2 of the cyclic prefix CP length;

[0041] If both parameter x and parameter y are not greater than 0.92, set parameter idxRegion to 3, indicating that the maximum delay spread is equal to the length of the cyclic prefix CP, and the maximum delay spread length corresponding to the filter is 1 cyclic prefix CP length.

[0042] In step S5, for a 2 transmit - 2 receive system, calculate the maximum delay spread idxRegion(iRx, iTx) estimated on different antenna pairs, and the final estimated result takes the maximum value among them, that is:

[0043] idxRegion = max(idxRegion(iRx, iTx));

[0044] where iRx = 0, 1 and iTx = 0, 1.

[0045] A device for estimating the maximum delay spread in a wireless ad - hoc network, characterized in that it includes a memory and a processor; the memory is used to store a computer program, and the processor is used to implement the method for estimating the maximum delay spread in the above - mentioned wireless ad - hoc network when executing the computer program.

[0046] A readable storage medium, characterized in that a computer program is stored on the readable storage medium, and the computer program implements the method for estimating the maximum delay spread in the above - mentioned wireless ad - hoc network when executed by a processor.

[0047] The beneficial effect of the present invention is that: for the main application scenarios and pilot patterns of the wireless ad - hoc network, the method for estimating the maximum delay spread in the wireless ad - hoc network provides an algorithm for estimating the maximum delay spread, which can clearly divide the delay spread regions in different scenarios, and then estimate the maximum delay spread of the channel. Description of the Drawings

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0049] Figure 1 Schematic diagram of the maximum delay spread of the present invention.

[0050] Figure 2 Schematic diagram of the PDP spectrum filter of the present invention.

[0051] Figure 3 Schematic diagram of the method for estimating the maximum delay spread in the wireless ad hoc network of the present invention. Detailed implementation manners

[0052] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0053] Since the PDP spectrum and the frequency-domain correlation are Fourier transforms of each other, filtering the PDP spectrum in the time domain is equivalent to multiplying the frequency-domain correlation by the coefficients corresponding to a set of filters in the frequency domain. Therefore, the key to the method for estimating the maximum delay spread in this wireless ad hoc network lies in the selection of the frequency-domain correlation and the filter order. During the selection process, simulations were carried out for different channel conditions and high, medium, and low signal-to-noise ratio scenarios. In the simulations, three aspects were mainly considered: the correlation length, the frequency-domain interval of the correlation, and the correlation combination.

[0054] As Figure 3 shown, the method for estimating the maximum delay spread in this wireless ad hoc network includes the following steps:

[0055] Step S1: Receive the signal r;

[0056] Step S2: Calculate the frequency-domain channel response h, that is, the conjugate product of the signal at the pilot position and the reference symbol;

[0057] In the above step S2, the calculation process is as follows:

[0058] Step S2.1: Extract the signal value r j at the pilot position p pj from the received signal r;

[0059] Step S2.2, calculate the conjugate complex number of the reference symbol s j ; ;

[0060] Step S2.3, calculate the conjugate product h of the pilot position signal and the reference symbol j ;

[0061] ;

[0062] Step S2.4, aggregate the product results at all pilot positions into a vector h;

[0063] ;

[0064] where v is the total number of positions of the known pilot symbols.

[0065] Step S3, calculate the frequency-domain correlation Corr(i) at the i-th point, and the calculation formula is as follows:

[0066] ,

[0067] where is the number of pilots on each reference symbol, h(k) is the frequency-domain channel response of the k-th point of the pilot symbol, is the conjugate of the frequency-domain channel response of the (k + i)-th point of the pilot symbol , and L is the minimum frequency-domain correlation length required to restore the PDP shape;

[0068] Through simulation analysis, the factor that has the greatest impact on restoring the PDP shape using frequency-domain correlation is the correlation length L.

[0069] In the said Step S3, according to the simulation results, the minimum frequency-domain correlation length L required to restore the PDP shape is 72;

[0070] ;

[0071] where Nlag represents the number of points of the frequency-domain correlation, and delta represents the correlation interval;

[0072] To reduce the computational complexity, the delta value is customarily selected as 2, and the Nlag value is 36, that is, it is necessary to calculate Corr(0), Corr(2), Corr(4),..., Corr(70). Therefore, in the calculation formula of the frequency-domain correlation Corr(i), .

[0073] In the said Step S3, since the frequency-domain correlation of different symbols changes slowly on the same transceiver antenna pair, the alpha filter is used to update the value of the signal based on the weighted average of the current value and the historical value;

[0074] For the same symbol, the PDP spectra on different transceiver antenna pairs are different, so the corresponding frequency-domain correlation is not suitable for combining or averaging; for a 2 transmit and 2 receive system, calculate the frequency-domain correlation on different antenna pairs, that is:

[0075] ,

[0076] where iRx is the index of the Receiver at the receiving end and iTx is the index of the Transmitter at the transmitting end.

[0077] Step S4, calculate the product of the frequency-domain correlation and the filtering coefficient , and the calculation formula is as follows:

[0078] ,

[0079] where are 3 groups of filtering coefficients corresponding to three filters;

[0080] The maximum delay spread lengths corresponding to the filters are 1 / 4 of the cyclic prefix CP length, 1 / 2 of the cyclic prefix CP length, and 1 cyclic prefix CP length respectively.

[0081] Step S5, post-process the product f and select the gear with the maximum delay spread, specifically as follows:

[0082] Use to perform normalization to obtain parameters and , that is

[0083] ,

[0084] If both parameter x and parameter y are greater than 0.92, set parameter idxRegion to 1, the maximum delay spread is one-quarter of the cyclic prefix CP, and the maximum delay spread length corresponding to the filter is 1 / 4 cyclic prefix CP length;

[0085] If parameter x is not greater than 0.92, but parameter y is greater than 0.92, set parameter idxRegion to 2, indicating that the maximum delay spread is half of the cyclic prefix CP, and the maximum delay spread length corresponding to the filter is 1 / 2 cyclic prefix CP length;

[0086] If both parameter x and parameter y are not greater than 0.92, set parameter idxRegion to 3, indicating that the maximum delay spread is equal to the length of the cyclic prefix CP, and the maximum delay spread length corresponding to the filter is 1 cyclic prefix CP length.

[0087] Through parameter and parameter The pseudocode for selecting the value of the maximum delay spread is as follows:

[0088] if x>0.92&&y>0.92

[0089] idxRegion = 1; % max delay spread = CP / 4

[0090] elseif y>0.92

[0091] idxRegion = 2; % max delay spread = CP / 2

[0092] else

[0093] idxRegion = 3; % max delay spread = CP

[0094] end

[0095] In step S5, for a 2-transmitter and 2-receiver system, the maximum delay spread idxRegion(iRx, iTx) estimated on different antenna pairs is calculated, and the final estimated result takes the maximum value among them, that is:

[0096] idxRegion = max(idxRegion(iRx, iTx));

[0097] where iRx = 0, 1 and iTx = 0, 1.

[0098] The method for estimating the maximum delay spread in this wireless ad hoc network uses the idea similar to that of a band-pass filter. By designing the corresponding passband and stopband widths, a PDP spectral filter similar to the shape of a band-pass filter is constructed, as Figure 2 shown.

[0099] The device for estimating the maximum delay spread in this wireless ad hoc network includes a memory and a processor; the memory is used to store a computer program, and the processor is used to implement the method for estimating the maximum delay spread in the above-mentioned wireless ad hoc network when executing the computer program.

[0100] A computer program is stored on this readable storage medium, and when the computer program is executed by a processor, the method for estimating the maximum delay spread in the above-mentioned wireless ad hoc network is implemented.

[0101] Compared with the prior art, the method for estimating the maximum delay spread in the wireless ad hoc network provides an algorithm for estimating the maximum delay spread for the main application scenarios and pilot patterns of the wireless ad hoc network. Through simulation analysis of different channel conditions and high, medium, and low signal-to-noise ratio scenarios, the proposed scheme can clearly divide the delay spread regions in different scenarios, and then estimate the maximum delay spread of the channel.

[0102] The above-described embodiments are only one of the specific implementation manners of the present invention, and the ordinary changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for estimating the maximum delay spread in a wireless ad-hoc network, characterized in that: The following steps are involved: Step S1, receiving a signal r; Step S2, calculating the frequency domain channel response h, that is, the conjugate product of the pilot position signal and the reference symbol; Step S3: Calculate the frequency domain correlation Corr(i) of the i-th point. The calculation formula is as follows: ， Among them, is the number of pilots on each reference symbol, is the frequency-domain channel response at the k-th point of the pilot symbol, is the frequency-domain channel response at the (k + i)-th point of the pilot symbol is the conjugate, and L is the minimum frequency-domain correlation length required to recover the PDP shape; Step S4: Calculate the product of the frequency-domain correlation and the filtering coefficient , and the calculation formula is as follows: ， Among them, are three groups of filtering coefficients corresponding to three filters; The maximum delay spread length corresponding to the filter is divided into 1 / 4 cyclic prefix CP length, 1 / 2 cyclic prefix CP length and 1 cyclic prefix CP length; Step S5. Post-process the product (m), and select the gear with the maximum delay spread, specifically as follows: Normalize the product (m) to obtain the parameters and , i.e.: ， If both parameter x and parameter y are greater than 0.92, the parameter idxRegion is set to 1, the maximum delay spread is one quarter of the cyclic prefix CP, and the maximum delay spread length corresponding to the filter is 1 / 4 of the cyclic prefix CP length; If the parameter x is not greater than 0.92, but the parameter y is greater than 0.92, the parameter idxRegion is set to 2, indicating that the maximum delay spread is half of the cyclic prefix CP, and the maximum delay spread length corresponding to the filter is 1 / 2 of the cyclic prefix CP length; If both parameter x and parameter y are not greater than 0.92, the parameter idxRegion is set to 3, indicating that the maximum delay spread is equal to the length of the cyclic prefix CP, and the maximum delay spread length corresponding to the filter is 1 cyclic prefix CP length.

2. The method for estimating the maximum delay spread in a wireless ad hoc network according to claim 1, wherein: In step S2, the calculation process is as follows: Step S2.1: Extract the pilot position p from the received signal r j and the signal value r pj ; Step S2.2, calculate the conjugate complex number of the reference symbol s j ;​ Step S2.3, calculate the frequency-domain channel response h j , and the calculation formula is as follows: ， Step S2.4, summarizing the product results of all pilot positions into a vector h; ， Wherein, v is the total number of known pilot symbol positions.

3. The method for estimating the maximum delay spread in a wireless ad hoc network according to claim 1, wherein: In step S3, the minimum frequency domain correlation length L required for restoring the PDP shape is 72; ， Among them, Nlag represents the number of frequency domain correlation points, and delta represents the correlation interval; To reduce the computational complexity, the delta value is customarily selected as 2, and the Nlag value is 36. That is, Corr(0), Corr(2), Corr(4),..., Corr(70) need to be calculated. Therefore, in the calculation formula of the frequency-domain correlation Corr(i), .

4. The method for estimating the maximum delay spread in a wireless ad hoc network according to claim 3, wherein: In step S3, the frequency domain correlation of different symbols on the same transmitting and receiving antenna pair changes slowly, and alpha filtering is used to update the signal value according to the weighted average of the current value and the historical value.

5. The method for estimating the maximum delay spread in a wireless ad hoc network according to claim 3, wherein: In step S3, the same symbol has different PDP spectra on different transmit and receive antenna pairs, so the corresponding frequency domain correlation is not suitable for merging or averaging. For a 2-transmit 2-receive system, the frequency domain correlation on different antenna pairs is calculated, that is: ， Among them, iRx is the index of the receiver, and iTx is the index of the transmitter.

6. The method for estimating the maximum delay spread in a wireless ad hoc network according to claim 5, wherein: In step S5, for a 2-transmit 2-receive system, the maximum delay spread idxRegion(iRx,iTx) estimated on different antenna pairs is calculated, and the final estimation result is the maximum value, that is: idxRegion = max(idxRegion(iRx, iTx)); Where iRx=0,1,iTx=0,1.

7. An apparatus for estimating the maximum delay spread in a wireless ad hoc network, characterized in that: It comprises a memory and a processor; the memory is used to store a computer program, and the processor is used to implement the maximum delay spread estimation method in a wireless ad hoc network as described in any one of claims 1 to 6 when executing the computer program.

8. A readable storage medium, characterized in that: The readable storage medium stores a computer program, and when the computer program is executed by a processor, the maximum delay spread estimation method in a wireless ad hoc network according to any one of claims 1 to 6 is implemented.

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