Maximum delay spread estimation method and device in wireless ad hoc network, and storage medium

Abstract

The invention relates to the technical field of wireless communication, in particular to a maximum delay spread estimation method and device in a wireless ad hoc network and a storage medium. According to the maximum delay spread estimation method in the wireless ad hoc network, after a signal r is received, the conjugate product h of a pilot frequency position signal and a reference symbol is calculated firstly, then the frequency domain correlation Corr and the product f (m) of the frequency domain correlation and a filter coefficient are calculated, post-processing is conducted on the product f (m), and the gear of the maximum delay spread is selected. According to the maximum time delay spread estimation method in the wireless ad hoc network, an estimation algorithm of the maximum time delay spread is provided for main application scenes and pilot frequency patterns of the wireless ad hoc network, time delay spread areas can be clearly divided in different scenes, and then the maximum time delay spread of a channel is estimated.

Description

Technical Field

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

[0002] Wireless self-organizing network is a new type of network. It breaks through the geographical limitations of traditional wireless cellular networks. It can achieve rapid networking without relying on any communication infrastructure, and relies on the mutual cooperation between wireless terminals to complete the establishment, maintenance and information transmission of the network. It can achieve faster, more convenient and more efficient deployment, and is especially suitable for communication needs in certain emergency situations.

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

[0004] By classifying common wireless channels, their 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 best-matching filter can be selected, and its corresponding length is the maximum delay spread that needs to be estimated.

[0005] The LMMSE channel estimation algorithm based on maximum delay spread also has a large number of applications and optimization solutions in the algorithms of various wireless receiving devices. By designing a suitable filter to divide the time domain length of the received signal PDP into bins and then estimate the maximum delay spread, it is a solution with high accuracy and low complexity.

[0006] In wireless ad hoc networks, if more accurate channel estimation is to be achieved, higher requirements are placed on the accuracy of the maximum delay spread estimation algorithm. However, since the main application scenarios of wireless ad hoc networks and the pilot pattern design of wireless ad hoc networks are different from wireless public networks such as 3G / LTE / NR, the maximum delay spread estimation algorithm in wireless ad hoc networks also needs to be redesigned.

[0007] In order to solve the above problem, the present invention proposes a maximum delay spread estimation method in a wireless ad hoc network. Summary of the invention

[0008] In order to make up for the defects of the prior art, the present invention provides a simple and efficient maximum delay spread estimation method in a wireless ad hoc network.

[0009] The present invention is achieved through the following technical solutions: A method for estimating maximum delay spread in a wireless ad hoc network, characterized in that it comprises the following steps: 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; In step S2, the calculation process is as follows: Step S2.1: Extract pilot position p from received signal r j The signal value at r pj ; Step S2.2, calculate the reference symbol s j The complex conjugate of ; Step S2.3: Calculate the frequency domain channel response h j , 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.

[0010] Step S3, calculate the frequency domain correlation Corr(i) of the i-th point, and the calculation formula is as follows: , in, is the number of pilots on each reference symbol, h(k) is the frequency domain channel response of the kth point of the pilot symbol, is the frequency domain channel response of the pilot symbol at point k+i The conjugate of , L is the minimum frequency domain correlation length required to recover the PDP shape; In step S3, according to the simulation results, the minimum frequency domain correlation length L required to restore 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 custom delta value is selected as 2, then 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), .

[0011] In step S3, due to different symbols, the frequency domain correlation on the same transmitting and receiving antenna pair changes slowly, and an alpha filter is used to update the signal value according to the weighted average of the current value and the historical value; However, for the same symbol, the PDP spectra on different transmit and receive antenna pairs are different, 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.

[0012] Step S4: Calculate the product of frequency domain correlation and filter coefficient , the calculation formula is as follows: , in, There are three sets of filter coefficients corresponding to the three filters; The maximum delay extension 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.

[0013] Step S5: post-process the product f and select the gear with the maximum delay spread, as follows: use Normalize and get the parameters and ,Right now , 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.

[0014] 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.

[0015] A maximum delay spread estimation device 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 above-mentioned maximum delay spread estimation method in the wireless ad hoc network when executing the computer program.

[0016] A readable storage medium, characterized in that: a computer program is stored on the readable storage medium, and when the computer program is executed by a processor, the maximum delay spread estimation method in the wireless ad hoc network is implemented.

[0017] The beneficial effects of the present invention are as follows: the maximum delay spread estimation method in the wireless ad hoc network provides a maximum delay spread estimation algorithm for the main application scenarios and pilot patterns of the wireless ad hoc network, which can clearly divide the delay spread area in different scenarios and further estimate the maximum delay spread of the channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 This is a schematic diagram of the maximum delay extension of the present invention.

[0020] Figure 2 Schematic diagram of the PDP spectrum filter of the present invention.

[0021] Figure 3 It is a schematic diagram of the maximum delay spread estimation method in the wireless ad hoc network of the present invention. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0023] 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 with a set of filter coefficients in the frequency domain. Therefore, the key to the maximum delay spread estimation method in the wireless ad hoc network lies in the selection of frequency domain correlation and filter order. During the selection process, simulations were conducted on different channel conditions and high, medium and low signal-to-noise ratio scenarios. The simulations mainly considered three aspects: correlation length, correlation frequency domain interval and correlation merging.

[0024] like Figure 3 As shown, the maximum delay spread estimation method in the wireless ad hoc network includes the following steps: 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; In step S2, the calculation process is as follows: Step S2.1: Extract pilot position p from received signal r j The signal value at r pj ; Step S2.2, calculate the reference symbol s j The complex conjugate of ; Step S2.3, calculate the conjugate product h of the pilot position signal and the reference symbol j ; ; 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.

[0025] Step S3, calculate the frequency domain correlation Corr(i) of the i-th point, and the calculation formula is as follows: , in, is the number of pilots on each reference symbol, h(k) is the frequency domain channel response of the kth point of the pilot symbol, is the frequency domain channel response of the pilot symbol at point k+i The conjugate of , L is the minimum frequency domain correlation length required to recover the PDP shape; Through simulation analysis, it is found that the factor that has the greatest impact on restoring the PDP shape using frequency domain correlation is the correlation length L.

[0026] In step S3, according to the simulation results, the minimum frequency domain correlation length L required to restore 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 custom delta value is selected as 2, then 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), .

[0027] In step S3, due to different symbols, the frequency domain correlation on the same transmitting and receiving antenna pair changes slowly, and an alpha filter is used to update the signal value according to the weighted average of the current value and the historical value; However, for the same symbol, the PDP spectra on different transmit and receive antenna pairs are different, 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.

[0028] Step S4: Calculate the product of frequency domain correlation and filter coefficient , the calculation formula is as follows: , in, There are three sets of filter coefficients corresponding to the three filters; The maximum delay extension 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.

[0029] Step S5: post-process the product f and select the gear with the maximum delay spread, as follows: use Normalize and get the parameters and ,Right now , 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.

[0030] By parameters and parameters The pseudo code for selecting the maximum delay spread value is as follows: if x>0.92&&y>0.92 idxRegion = 1; % max delay spread = CP / 4 elseif y>0.92 idxRegion = 2; % max delay spread = CP / 2 else idxRegion = 3; % max delay spread = CP end 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.

[0031] The maximum delay spread estimation method in the wireless ad hoc network uses a bandpass filter-like idea to construct a PDP spectrum filter similar to the bandpass filter shape by designing the corresponding passband and stopband widths, such as Figure 2 shown.

[0032] The maximum delay spread estimation device in a wireless ad hoc network comprises a memory and a processor; the memory is used to store a computer program, and the processor is used to implement the above-mentioned maximum delay spread estimation method in a wireless ad hoc network when executing the computer program.

[0033] 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 the wireless ad hoc network is implemented.

[0034] Compared with the prior art, the maximum delay spread estimation method in wireless ad hoc networks provides a maximum delay spread estimation algorithm for the main application scenarios and pilot patterns of wireless ad hoc networks. Through simulation analysis of different channel conditions and high, medium and low signal-to-noise ratio scenarios, this solution can clearly divide the delay spread area in different scenarios, and then estimate the maximum delay spread of the channel.

[0035] The embodiment described above is only one specific implementation of the present invention. Common 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 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: ， in, is the number of pilots per reference symbol, is the frequency domain channel response of the kth pilot symbol, is the frequency domain channel response of the pilot symbol at point k+i The conjugate of , L is the minimum frequency domain correlation length required to recover the PDP shape; Step S4: Calculate the product of frequency domain correlation and filter coefficient , the calculation formula is as follows: ， in, There are three groups of filter coefficients corresponding to the 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: multiply the product (m) Perform post-processing and select the gear with the maximum delay extension, as follows: Pair product (m) is normalized to obtain the parameter and ,Right now: ， 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 maximum delay spread estimation method in a wireless ad hoc network according to claim 1, characterized in that: In step S2, the calculation process is as follows: Step S2.1: Extract pilot position p from received signal r j The signal value at r pj ; Step S2.2, calculate the reference symbol s j The complex conjugate of ; Step S2.3: Calculate the frequency domain channel response h j , 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 maximum delay spread estimation method in a wireless ad hoc network according to claim 1, characterized in that: 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 custom delta value is selected as 2, then 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 maximum delay spread estimation method in a wireless ad hoc network according to claim 3, characterized in that: 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 maximum delay spread estimation method in a wireless ad hoc network according to claim 3, characterized in that: 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 maximum delay spread estimation method in a wireless ad hoc network according to claim 5, characterized in that: 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. A maximum delay spread estimation device 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.

Images