CN118174993A

CN118174993A - Method, system and chip for determining maximum time delay expansion value of channel

Info

Publication number: CN118174993A
Application number: CN202410567043.1A
Authority: CN
Inventors: 王鑫; 赵旭; 甘杰; 曲行根; 周顺伟; 孙丽国; 汪婧
Original assignee: Beijing Smartchip Microelectronics Technology Co Ltd
Current assignee: Beijing Smartchip Microelectronics Technology Co Ltd
Priority date: 2024-05-09
Filing date: 2024-05-09
Publication date: 2024-06-11

Abstract

The invention relates to the technical field of wireless communication, and discloses a method, a system and a chip for determining a maximum time delay expansion value of a channel. The determining method comprises the following steps: determining an initial channel estimation value of a pilot signal in a frequency domain according to a transmission signal and the channel estimation value of the pilot signal in a time domain, which are transmitted to a terminal by a base station, and the number of advance points relative to the initial position of a Fourier transform demodulation window of the pilot signal; denoising the initial channel estimation value of the pilot signal in the frequency domain to obtain a denoised channel estimation value; determining a power spectrum after noise reduction according to the channel estimation value after noise reduction; and determining a maximum time delay expansion value of the channel according to the noise-reduced power spectrum and a constraint threshold. The invention effectively improves the channel delay expansion measurement precision under low signal-to-noise ratio so as to improve the demodulation performance of the OFDM system.

Description

Method, system and chip for determining maximum time delay expansion value of channel

Technical Field

The present invention relates to the field of wireless communications technologies, and in particular, to a method, a system, and a chip for determining a maximum delay spread value of a channel.

Background

The characteristics of large bandwidth, low time delay and high reliability of the 5G network provide necessary network foundation for the service and promote the continuous enrichment of the service. With the promotion of the development of service enrichment by the 5G network, the demands of dense urban areas, indoor and other multipath rich environments are more and more strong. The 5G adopts an OFDM modulation technology, the multipath effect of a wireless channel causes adjacent symbols before and after OFDM signals to be overlapped, the error OFDM symbol timing synchronization can cause an FFT processing window to contain values of two continuous OFDM symbols, inter-symbol interference (ISI) and inter-subcarrier interference (ICI) are brought, and the performance of an OFDM system is seriously affected. The method can be applied to various aspects of symbol timing synchronization, interference elimination and the like.

The maximum delay spread estimate typically requires the UE to measure the earliest and latest times of arrival of the pilot signal paths and to subtract the two values. Obviously, the estimation accuracy of the maximum delay spread value is directly related to the accurate detection of the signal path. Under a radio channel, a signal path is affected by the radio channel environment. Under the condition of LoS (Line-of-sight), the detection of the signal path achieves the optimal accurate detection performance. Unfortunately, in densely populated areas, obstructions are often present, resulting in multipath and NLoS (non line of sight) conditions, which cause the signal to fade deeply, preventing accurate signal arrival time measurements. Especially for 5G cell edge users, due to low received signal strength, multipath rich environments such as dense urban areas and indoor environments enable multipath signals to be submerged in noise, and effective path detection and maximum delay spread estimation failure are extremely easy to cause. Therefore, research on a maximum delay spread estimation technology of an OFDM system such as 5G under a low signal to noise ratio in a multipath environment such as a city is needed.

Disclosure of Invention

The invention aims to provide a method, a system and a chip for determining a maximum delay spread value, which effectively improve the signal effective path detection probability under low signal-to-noise ratio, thereby improving the channel maximum delay spread estimation precision of 5G network cell edge users under urban environment.

In order to achieve the above object, a first aspect of the present invention provides a method for detecting an effective path of a signal, the method comprising: determining an initial channel estimation value of a pilot signal on a frequency domain according to a transmission signal and the channel estimation value of the pilot signal on a time domain, which are transmitted to a terminal by a base station, and the number of advance points relative to the initial position of a Fourier transform demodulation window of the pilot signal; denoising the initial channel estimation value of the pilot signal on a frequency domain to obtain a denoised channel estimation value; determining a power spectrum after noise reduction according to the channel estimation value after noise reduction; and determining a maximum time delay expansion value of the channel according to the noise-reduced power spectrum and a constraint threshold.

Preferably, the determining the initial channel estimation value of the pilot signal in the frequency domain includes: determining a transmitting signal and a receiving signal of the pilot signal on a frequency domain according to the transmitting signal and the channel estimation value of the pilot signal on the time domain and the number of the advance points; and determining the initial channel estimation value according to the transmission signal and the receiving signal of the pilot frequency signal in the frequency domain.

Preferably, in the case that the pilot signal is located in the first OFDM symbol of the s-th slot of each frame in the 5G signal, the determining the power spectrum after noise reduction includes: according to the channel estimation value after noise reductionThe power spectrum v (n),/>, after noise reduction is determined by the following equationWherein q represents the position of the subcarrier of the pilot signal in the frequency domain, and n represents the position of the pilot signal in the time domain, wherein 1.ltoreq.l.ltoreq.14; s is more than or equal to 1 and less than or equal to S and more than or equal to 10 and less than or equal to 640, and l and S are integers.

Preferably, the determining the channel maximum delay spread value includes: determining the earliest arrival time and the latest arrival time of the pilot signal according to the noise-reduced power spectrum and the constraint threshold; and determining the maximum delay spread value of the channel according to the time difference between the earliest arrival time and the latest arrival time of the pilot signal and the time domain sampling rate of the power spectrum.

Preferably, said determining the earliest and latest arrival times of the pilot signal comprises: determining the effective path position set of the pilot signal according to the power spectrum v (n) after noise reduction and the constraint threshold Th by the following formula：/>M is the number of effective diameters; and determining a minimum value and a maximum value in the effective path position set as the earliest arrival path time and the latest arrival path time respectively.

Preferably, the determining method further includes: determining the constraint threshold by: according to the power ratio of any two different paths in the effective path position set, the method satisfies the following conditionsA distribution that determines a constraint threshold corresponding to a first detection probability as a maximum constraint threshold and a constraint threshold corresponding to a second detection probability as a minimum constraint threshold, wherein the first detection probability is greater than the second detection probability; and determining any value in a range from the minimum constraint threshold to the maximum constraint threshold as the constraint threshold.

Preferably, the pilot signal includes: PRS, CSI-RS, or SSB.

Preferably, the noise reduction of the initial channel estimation value of the pilot signal in the frequency domain includes: and adopting CNN to reduce noise of the initial channel estimation value of the pilot signal in the frequency domain.

Through the technical scheme, the method and the device creatively determine the initial channel estimation value of the pilot signal on the frequency domain according to the transmission signal and the channel estimation value of the pilot signal transmitted to the terminal by the base station on the time domain and the advance point number of the initial position of the Fourier transform demodulation window relative to the pilot signal; then, the initial channel estimation value of the pilot signal on the frequency domain is subjected to noise reduction to obtain a noise-reduced channel estimation value; then, determining a power spectrum after noise reduction according to the channel estimation value after noise reduction; and finally, determining the maximum time delay expansion value of the channel according to the power spectrum after noise reduction and the constraint threshold. Therefore, the invention simplifies and efficiently determines the arrival time of the signal path under the low signal-to-noise ratio, thereby further determining the maximum time delay expansion of the channel based on the correction, effectively improving the estimation precision of the maximum time delay expansion of the channel under the low signal-to-noise ratio, improving the estimation precision of the maximum time delay expansion of the channel of the 5G network cell edge user under the urban environment, and providing parameter input for timing synchronization optimization and interference elimination.

A second aspect of the present invention provides a system for determining a maximum delay spread value of a channel, the system comprising: a first channel estimation means for determining an initial channel estimation value of a pilot signal transmitted from a base station to a terminal in a frequency domain based on a transmission signal and the channel estimation value of the pilot signal in a time domain and an advance point number with respect to a start position of a fourier transform demodulation window of the pilot signal; the second channel estimation device is used for carrying out noise reduction on the initial channel estimation value of the pilot signal on a frequency domain so as to obtain a channel estimation value after noise reduction; the power spectrum determining device is used for determining a power spectrum after noise reduction according to the channel estimation value after noise reduction; and the time delay expansion value determining device is used for determining the maximum time delay expansion value of the channel according to the power spectrum after noise reduction and the constraint threshold value.

The specific details and benefits of the system for determining a maximum delay spread value of a channel according to the embodiments of the present invention can be found in the above description of the method for determining a maximum delay spread value of a channel, which is not repeated here.

A third aspect of the present invention provides a computer readable storage medium having stored thereon a computer program which when executed by a processor implements the method of determining a channel maximum delay spread value.

A fourth aspect of the invention provides a chip for executing a computer program which when executed by said chip enables said determination of a channel maximum delay spread value.

A fifth aspect of the invention provides a computer program product comprising a computer program which, when executed by a processor, performs the determination of the channel maximum delay spread value.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The accompanying drawings are included to provide a further understanding of embodiments of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain, without limitation, the embodiments of the invention. In the drawings:

fig. 1 is a flowchart of a method for determining a maximum delay spread value of a channel according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a CNN provided by an embodiment of the present invention;

FIG. 3 is a graph showing CNN training results according to an embodiment of the present invention;

FIG. 4 is a block diagram of an implementation provided by an example of the present invention; and

Fig. 5 is a comparison chart of channel maximum delay spread estimation mean value results under a multipath channel according to an embodiment of the present invention.

Detailed Description

The following describes specific embodiments of the present invention in detail with reference to the drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.

Fig. 1 is a flowchart of a method for determining a maximum delay spread value of a channel according to an embodiment of the present invention. As shown in fig. 1, the determining method may include: step S101, determining an initial channel estimation value of a pilot signal in a frequency domain according to a transmission signal and the channel estimation value of the pilot signal in a time domain, which are transmitted to a terminal by a base station, and the number of advance points relative to the initial position of a Fourier transform demodulation window of the pilot signal; step S102, noise reduction is carried out on the initial channel estimation value of the pilot signal on a frequency domain so as to obtain a channel estimation value after noise reduction; step S103, determining a power spectrum after noise reduction according to the channel estimation value after noise reduction; and step S104, determining the maximum time delay expansion value of the channel according to the power spectrum after noise reduction and the constraint threshold.

The following explanation and explanation are made for each of the above steps, respectively. Wherein the base station may be a gNB (the next Generation Node B, next generation base station).

Step S101, determining an initial channel estimation value of a pilot signal in a frequency domain according to a transmission signal and the channel estimation value of the pilot signal in a time domain, which are transmitted to a terminal by a base station, and the number of advance points relative to the initial position of a Fourier transform demodulation window of the pilot signal.

Wherein the pilot signal may comprise: PRS (Positioning reference signal) REFERENCE SIGNAL, CSI-RS (CHANNEL STATE Information-REFERENCE SIGNAL, channel state Information reference signal), or SSB (Synchronization SIGNAL AND PBCH block ). The method of the present invention does not depend on any particular reference sign.

In order to ensure that the start position of the FFT demodulation window falls within the CP and avoid ISI (Inter Symbol Interference ), the start position of the fourier transform (FFT) demodulation window of the pilot signal is typically manually advanced by a certain number of points, referred to as the advance number of points relative to the start position of the FFT demodulation window of the pilot signal. The number of advance points of the starting position of the FFT demodulation window relative to the pilot signal is obtained by any existing method, and will not be described herein.

For step S101, the determining an initial channel estimation value of the pilot signal in the frequency domain includes: determining a transmitting signal and a receiving signal of the pilot signal on a frequency domain according to the transmitting signal and the channel estimation value of the pilot signal on the time domain and the number of the advance points; and determining the initial channel estimation value according to the transmission signal and the receiving signal of the pilot frequency signal in the frequency domain.

The embodiments of the present invention are described by taking the first OFDM symbol of the s-th slot of each frame in the 5G signal as an example. Wherein l is more than or equal to 1 and less than or equal to 14; s is more than or equal to 1 and less than or equal to S, wherein S is more than or equal to 10 and less than or equal to 640, and l and S are integers. S is specified by the standard, and reference is made specifically to the 5g ts38.211 standard (there are a wide variety of configurations depending on the different subcarrier bandwidths).

The transmission signal of the pilot signal in the time domain (the nth sample of the nth OFDM symbol of the s-th slot of each frame in the time domain) may be represented as follows:

，(1)

Where G is a CP (Cyclic Prefix) length, N is an OFDM symbol length, and G and N are both standard specifications, and reference may be made specifically to the 5G ts38.211 standard (there are many configurations according to different subcarrier bandwidths); l represents the number of OFDM symbols contained in each slot. The cyclic prefix is a repetition of the OFDM end symbol: 。

First, a transmission signal of the pilot signal in the time domain Fourier transforming to obtain the transmitted signal/>, in the frequency domain, of the pilot signal。

Second, assume the time domain Channel Impulse Response (CIR) isEach diameter is independent and meets complex Gaussian distribution/>The maximum delay is/>，/>Is the baseband sampling interval. M+1st multipathIs/>Consider that the received symbols have a synchronization bias/>And the synchronization position falls within the CP of interval [ -G,1] with frequency offset/>And initial random phase/>The OFDM received signal is expressed as:

，(2)

Wherein, Is power/>M is related to the actual channel environment of the OFDM received signal, and M is the number of paths of the actual channel, for example, if the paths of the actual channel are 6, then m=6.

Receiving a signalFrequency domain expression/>The method comprises the following steps:

，(3)

Thereby, the signal can be transmitted in time domain according to the pilot signal Determining the transmitted signal/>, of the pilot signal in the frequency domain; According to said/>Channel estimation value/>Start position of fourier transform demodulation windowDetermining the received signal/>, in the frequency domain, of the pilot signal, the advance point u and the formula (3) above(As shown in fig. 4).

In the formula (3), the amino acid sequence of the compound,(4) When/>Time,/>. ICI is inter-subcarrier interference caused by frequency offset.

The power spectrum/correlation spectrum v (n) can be expressed as:

，(5)

In the formula (5), the amino acid sequence of the compound, Representing the transmitted frequency domain pilot signal. q is the position of the frequency domain subcarrier where the pilot frequency is located, the value is related to the configuration of the base station, and the method is flexible and can refer to the specification 3GPP TS38.211.

According toAnd/>The initial channel estimate/>, may be determinedAs shown in fig. 4. On this basis, the following formula can also be determined according to the above formula (5):

，(6)

in the formula (6), the amino acid sequence of the compound, As noise and interference terms, when its power/>When larger, the channel is seriously affectedIs a test performance of (a). Residual frequency offset/>Can be controlled within 100Hz through frequency offset estimation, then there is/>。

As can be seen from the formula (5),Depending on the frequency domain channel estimate/>. When/>Is infinitely approaching toThen the noise and interference terms are eliminated,/>Infinite approach/>. Therefore, the problem of detection accuracy of the effective channel diameter is converted into the problem of frequency domain channel estimation accuracy.

S102, denoising the initial channel estimation value of the pilot signal in the frequency domain to obtain a denoised channel estimation value.

In particular, the initial channel estimate of the pilot signal in the frequency domain may be noise reduced using a CNN network.

In this embodiment, the pilot frequency resource grid in the frequency domain may be regarded as a two-dimensional image, the channel estimation problem is converted into an image processing problem, and CNN is used to denoise or improve the resolution. The CNN consists of an input layer, several hidden layers and an output layer, as shown in fig. 2. Each layer of network is composed of a plurality of neurons, and the output of each neuron is a nonlinear function of all neurons of the previous layer after weighted summation. The nonlinear function f typically employs Sigmod or Relu functions. The channel estimation value (as shown in fig. 4) output by the L-layer CNN network is:

，(7)

In the above-mentioned method, the step of, Is a weighting coefficient.

The L ₂ loss value after training with the p-th set of data is:

，(8)

In the method, in the process of the invention, Representing the p-th group of channel estimation training values,/>Is an ideal channel estimate, representing the p-th set of channel estimate supervision values.

Suppose that training setAnd (3) group data, wherein each iteration selects T group data for training, and the mean square error MSE output by each network iteration is as follows:

，(9)

Each iteration The sub-becomes 1 Epoch (when a complete data set passes through the neural network once and returns once, this process is called an Epoch). Vector/> by multiple epochsThe BP (Backpropagation, error back propagation) algorithm may be used to approximate the optimal solution, thereby completing the establishment of the channel estimation network.

The CNN simulation parameter configuration is shown in table 1 below. In the simulation, 1 PRS pilot symbol is configured, and a total of 104 pilot subcarriers, that is, channel estimation values, are rearranged into a 52x2 two-dimensional matrix, and input to the CNN network. As shown in fig. 3, under TU (Typical Urban channel) channel, the root mean square error RMSE of the channel after training is significantly reduced and stabilized compared with that before training. Wherein the training label is an ideal channel estimation valueIs an expression of (2).

TABLE 1 CNN simulation parameter configuration

And denoising the initial channel estimation value of the pilot signal in the frequency domain by adopting the CNN so as to obtain a denoised channel estimation value (namely, no noise or interference item).

The embodiment provides a method for estimating maximum delay spread of a channel by using CNN assistance. When the CNN network is used for assisting in measuring the maximum delay spread value, the type of the deep learning network is not limited to the CNN, and other deep learning models such as DNN and the like are also used. When the CNN network is used for assisting in channel maximum delay spread estimation, CNN network configuration is not limited to only using configuration parameters in simulation, but also comprises other feasible network parameter configuration.

The principle of the method for carrying out noise reduction on the correlation value by utilizing deep learning in the time domain so as to judge the effective diameter and carrying out channel maximum time delay expansion estimation is equivalent to the method. The invention carries out training noise reduction on the frequency domain channel estimation value, and the effects of frequency domain noise reduction and time domain noise reduction are equivalent.

When the CNN is used for assisting TOA measurement, the method is not only limited in a low signal-to-noise ratio environment, but also applicable to a measurement principle in a higher signal-to-noise ratio environment.

Step S103, determining a power spectrum after noise reduction according to the channel estimation value after noise reduction.

In the case that the pilot signal is located in the first OFDM symbol of the S-th slot of each frame in the 5G signal, for step S103, the determining the power spectrum after noise reduction includes:

As shown in fig. 4, according to the channel estimation value after noise reduction The power spectrum v (n) after noise reduction is determined by the following equation,

，(10)

Wherein q represents the position of the sub-carrier of the pilot signal in the frequency domain, and n represents the position of the pilot signal in the time domain, wherein 1.ltoreq.l.ltoreq.14; s is more than or equal to 1 and less than or equal to S and more than or equal to 10 and less than or equal to 640, and l and S are integers.

Because noise is eliminated, existing threshold decision methods based on noise power and SNR (signal to noise ratio) cannot be continued to be used. In the invention, the effective path detection is carried out by adopting the threshold method based on the maximum path power in the step S104, and the threshold are fixed values and are obtained by checking the critical value table of F distribution.

Step S104, determining the maximum time delay expansion value of the channel according to the power spectrum after noise reduction and the constraint threshold.

For step S104, the determining the channel maximum delay spread value includes: determining the earliest arrival time and the latest arrival time of the pilot signal according to the noise-reduced power spectrum and the constraint threshold; and determining the maximum delay spread value of the channel according to the time difference between the earliest arrival time and the latest arrival time of the pilot signal and the time domain sampling rate of the power spectrum.

Wherein said determining the earliest and latest arrival times of the pilot signal comprises: determining the effective path position set of the pilot signal according to the power spectrum v (n) after noise reduction and the constraint threshold Th by the following formula：/>M is the number of effective diameters; and determining a minimum value and a maximum value in the effective path position set as the earliest arrival path time and the latest arrival path time respectively.

Specifically, first, the effective path position set is determined by the following formula (11)(As shown in fig. 4):

。（11）

Then, through And/>And determining the earliest arrival path time and the latest arrival path time respectively.

The determining method further comprises the following steps: determining the constraint threshold by: according to the power ratio of any two different paths in the effective path position set, the method satisfies the following conditionsDetermining a constraint threshold corresponding to a first detection probability as a maximum constraint threshold and determining a constraint threshold corresponding to a second detection probability as a minimum constraint threshold by searching an F distribution critical value table, wherein the first detection probability is larger than the second detection probability; and determining any value in a range from the minimum constraint threshold to the maximum constraint threshold as the constraint threshold.

The power values based on each path of the channel meet the independent same distribution, and each path power spectrum v (n) meets the premise of chi-square distribution thatThe power ratio/>, of any two different pathsSatisfy the following requirementsDistribution is known by looking up a F distribution threshold table:

，

i.e. the ratio of any two path power values is less than or equal to Is P. For example, if the first detection probability is 97.5% and the second detection probability is 90%, the first detection probability is obtained/is >(E.g., th=1/19 for use in simulations). This is in view of/>Too small can cause false detection and too large can cause missed detection, so/>Is set in a suitable range.

The method for determining the effective path in this embodiment is applicable to the power spectrum after noise reduction, if noise is not eliminated, the effective path is submerged by the noise, so that the effective path cannot be determined by the ratio, and even the maximum signal path is likely to be noise.

After determining the earliest and latest arrival times, the channel maximum delay spread value D (as shown in fig. 4) is determined according to the time difference between the earliest and latest arrival times of the pilot signal and the time domain sampling rate T _s of the power spectrum and the following equation (12):

。（12）

The method for determining the maximum delay spread value of the channel can be applied to an OFDM system.

In summary, the present invention creatively determines an initial channel estimation value of a pilot signal transmitted to a terminal by a base station in a frequency domain according to a transmission signal and the channel estimation value of the pilot signal in a time domain and an advance point number of a start position of a fourier transform demodulation window relative to the pilot signal; then, the initial channel estimation value of the pilot signal on the frequency domain is subjected to noise reduction to obtain a noise-reduced channel estimation value; then, determining a power spectrum after noise reduction according to the channel estimation value after noise reduction; and finally, determining the maximum time delay expansion value of the channel according to the power spectrum after noise reduction and the constraint threshold. Therefore, the invention simplifies and efficiently determines the signal effective path arrival time under low signal-to-noise ratio, thereby determining the maximum time delay expansion value of the channel based on the earliest effective path arrival time and the latest effective path arrival time, effectively improving the estimation precision of the maximum time delay expansion value of the channel under low signal-to-noise ratio, improving the estimation precision of the maximum time delay expansion value of the channel of the 5G network cell edge user under urban environment, and providing parameter input for timing synchronization optimization and interference elimination.

The invention firstly converts the time domain correlation operation of the pilot signal for 5G positioning into the frequency domain channel estimation of the pilot sub-carrier, secondly utilizes the neural network to reduce noise to obtain a cleaner channel estimation value, finally converts the frequency domain channel into the time domain channel power spectrum, and utilizes the method of the self-adaptive threshold to detect the effective path of the signal.

Simulation comparison of RSTD error and positioning error of the proposed method and popular method under TU (Typical city) multipath channel is presented in table 2 below. Also included in table 2 are system simulation parameter settings.

Table 2 system simulation parameter configuration

Fig. 5 is a comparison of simulation performance of the maximum delay spread mean of the channel under TU multipath channel at a signal-to-noise ratio equal to-9 dB, -7dB, -5 dB. As shown by simulation results, the error between the method and the true value is within 1.6us, and the error between the popular method is above 4.5 us. The popular method carries out time domain correlation operation, the operation result is equivalent to the channel estimation value after untrained and noise reduction, the effective path detection is carried out by adopting a threshold method based on noise power, namely, if the power of a certain path is larger than a certain multiple of the noise power, the effective path is considered, because the multipath is submerged by the noise, the estimation performance is poor under the low signal-to-noise ratio, the channel after CNN training is closer to a perfect channel, and the noise of the channel estimation value is effectively removed, so the performance is better.

Taking one PRS reference symbol as an example, popular time domain correlation methods require (g+n) complex multiplication operations per sliding correlation, assuming a sliding CP length of G, and altogether require G (g+n) complex multiplication. The method needs to perform FFT/IFFT operation of N points, and the number of complex multiplication times isThe channel estimation needs K times of multiplication operations, wherein the number of pilot frequencies for the K designated position is the same as that of the K designated position+K) complex multiplications. Taking parameter configuration in simulation as an example, the complexity of the method is about 13% of the popular method, and the operation can multiplex the FFT demodulation module of the data OFDM symbol. In addition, a separate CNN training module is needed, training data is generated by simulation and is trained online, and training can be performed in the future by collecting real channel data.

Therefore, compared with the popular scheme, the channel maximum time delay expansion estimation scheme based on the neural network improves the positioning accuracy in the multipath channel environment under the low signal-to-noise ratio. And finally, verifying the effectiveness of the method through the maximum time delay expansion estimation of the channel of the 5G PRS, wherein the method not only can be applied to the maximum time delay expansion precision improvement of the channel of the 5G system, but also can provide references for positioning methods of other OFDM systems, such as LTE (Long Term Evolution, long-term evolution), WIFI and the like.

An embodiment of the present invention provides a system for determining a maximum delay spread value of a channel, where the determining system includes: a first channel estimation means for determining an initial channel estimation value of a pilot signal transmitted from a base station to a terminal in a frequency domain based on a transmission signal and the channel estimation value of the pilot signal in a time domain and an advance point number with respect to a start position of a fourier transform demodulation window of the pilot signal; the second channel estimation device is used for carrying out noise reduction on the initial channel estimation value of the pilot signal on a frequency domain so as to obtain a channel estimation value after noise reduction; the power spectrum determining device is used for determining a power spectrum after noise reduction according to the channel estimation value after noise reduction; and the time delay expansion value determining device is used for determining the maximum time delay expansion value of the channel according to the power spectrum after noise reduction and the constraint threshold value.

Preferably, the first channel estimation device includes: the signal determining module is used for determining a sending signal and a receiving signal of the pilot signal in a frequency domain according to the sending signal and the channel estimation value of the pilot signal in the time domain and the number of the advance points; and the channel estimation module is used for determining the initial channel estimation value according to the transmission signal and the receiving signal of the pilot frequency signal in the frequency domain.

Preferably, in the case that the pilot signal is located in the first OFDM symbol of the s-th slot of each frame in the 5G signal, the power spectrum determining means is configured to determine the power spectrum after noise reduction, including: according to the channel estimation value after noise reductionThe power spectrum v (n),/>, after noise reduction is determined by the following equationWherein q represents the position of the subcarrier of the pilot signal in the frequency domain, and n represents the position of the pilot signal in the time domain, wherein 1.ltoreq.l.ltoreq.14; s is more than or equal to 1 and less than or equal to S and more than or equal to 10 and less than or equal to 640, and l and S are integers.

Preferably, the delay spread value determining means includes: the time determining module is used for determining the earliest arrival time and the latest arrival time of the pilot signal according to the power spectrum after noise reduction and the constraint threshold; and a time delay spread value determining module, configured to determine the maximum time delay spread value of the channel according to a time difference between the earliest arrival time and the latest arrival time of the pilot signal and a time domain sampling rate of the power spectrum.

Preferably, the time determining module includes: a set determining unit for determining the effective path position set of the pilot signal according to the power spectrum v (n) after noise reduction and the constraint threshold Th by the following formula：

M is the number of effective diameters; and

And the time determining unit is used for determining the minimum value and the maximum value in the effective path position set as the earliest arrival path time and the latest arrival path time respectively.

Preferably, the determining system further comprises: threshold determining means for determining the constraint threshold by: according to the power ratio of any two different paths in the effective path position set, the method satisfies the following conditionsA distribution that determines a constraint threshold corresponding to the first detection probability as a maximum constraint threshold and a constraint threshold corresponding to the second detection probability as a minimum constraint threshold; and determining any value in a range from the minimum constraint threshold to the maximum constraint threshold as the constraint threshold.

Preferably, the pilot signal includes: PRS, CSI-RS, or SSB.

Preferably, the second channel estimation device is configured to perform noise reduction on the initial channel estimation value of the pilot signal in a frequency domain, including: and adopting CNN to reduce noise of the initial channel estimation value of the pilot signal in the frequency domain.

Specific details and benefits of the positioning system provided by the embodiments of the present invention can be found in the above description of the positioning method, and are not repeated here.

An embodiment of the present invention provides a computer readable storage medium having a computer program stored thereon, which when executed by a processor implements the method for determining a maximum delay spread value of a channel.

An embodiment of the present invention provides a chip for executing a computer program, where the computer program when executed by the chip implements the method for determining the maximum delay spread value of the channel.

Specifically, the present embodiment provides a chip including: a processor; a memory for storing a computer program for execution by the processor; the processor is configured to read the computer program from the memory and execute the computer program to implement the method for determining the maximum delay spread value of the channel.

An embodiment of the invention provides a computer program product comprising a computer program which, when executed by a processor, implements the method of determining a maximum delay spread value for a channel.

The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the scope of the technical concept of the present invention, and all the simple modifications belong to the protection scope of the present invention.

In addition, the specific features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various possible combinations are not described further.

Those skilled in the art will appreciate that all or part of the steps in implementing the methods of the embodiments described above may be implemented by a program stored in a storage medium, including instructions for causing a single-chip microcomputer, chip or processor (processor) to perform all or part of the steps of the methods of the embodiments described herein. And the aforementioned storage medium includes: a usb disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.

It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

Moreover, any combination of the various embodiments of the invention can be made without departing from the spirit of the invention, which should also be considered as disclosed herein.

Claims

1. A method for determining a maximum delay spread value of a channel, the method comprising:

Determining an initial channel estimation value of a pilot signal on a frequency domain according to a transmission signal and the channel estimation value of the pilot signal on a time domain, which are transmitted to a terminal by a base station, and the number of advance points relative to the initial position of a Fourier transform demodulation window of the pilot signal;

denoising the initial channel estimation value of the pilot signal on a frequency domain to obtain a denoised channel estimation value;

determining a power spectrum after noise reduction according to the channel estimation value after noise reduction; and

And determining a maximum time delay expansion value of the channel according to the power spectrum after noise reduction and a constraint threshold.

2. The method of determining according to claim 1, wherein said determining an initial channel estimate for the pilot signal in the frequency domain comprises:

Determining a transmitting signal and a receiving signal of the pilot signal on a frequency domain according to the transmitting signal and the channel estimation value of the pilot signal on the time domain and the number of the advance points; and

And determining the initial channel estimation value according to the transmission signal and the receiving signal of the pilot frequency signal in the frequency domain.

3. The method according to claim 1, wherein in the case where the pilot signal is located in the first OFDM symbol of the s-th slot of each frame in the 5G signal, the determining the power spectrum after noise reduction includes:

According to the channel estimation value after noise reduction The power spectrum v (n) after noise reduction is determined by the following equation,

，

Where q represents the position of the sub-carrier of the pilot signal in the frequency domain, n represents the position of the pilot signal in the time domain,

Wherein l is more than or equal to 1 and less than or equal to 14; s is more than or equal to 1 and less than or equal to S and more than or equal to 10 and less than or equal to 640, and l and S are integers.

4. The method of determining according to claim 3, wherein determining the channel maximum delay spread value comprises:

Determining the earliest arrival time and the latest arrival time of the pilot signal according to the noise-reduced power spectrum and the constraint threshold; and

And determining the maximum time delay expansion value of the channel according to the time difference between the earliest arrival time and the latest arrival time of the pilot signal and the time domain sampling rate of the power spectrum.

5. The method of determining according to claim 4, wherein the determining the earliest and latest arrival times of the pilot signal comprises:

Determining the effective path position set of the pilot signal according to the power spectrum v (n) after noise reduction and the constraint threshold Th by the following formula ：

M is the number of effective diameters; and

And respectively determining the minimum value and the maximum value in the effective path position set as the earliest arrival path time and the latest arrival path time.

6. The determination method according to claim 5, characterized in that the determination method further comprises: determining the constraint threshold by:

according to the power ratio of any two different paths in the effective path position set, the method satisfies the following conditions A distribution that determines a constraint threshold corresponding to a first detection probability as a maximum constraint threshold and a constraint threshold corresponding to a second detection probability as a minimum constraint threshold, wherein the first detection probability is greater than the second detection probability; and

Any value in the range from the minimum constraint threshold to the maximum constraint threshold is determined as the constraint threshold.

7. The method of determining according to claim 1, wherein the pilot signal comprises: PRS, CSI-RS, or SSB.

8. The method of determining of claim 1, wherein said denoising said initial channel estimate of said pilot signal in the frequency domain comprises: and adopting CNN to reduce noise of the initial channel estimation value of the pilot signal in the frequency domain.

9. A system for determining a maximum delay spread of a channel, the system comprising:

a first channel estimation means for determining an initial channel estimation value of a pilot signal transmitted from a base station to a terminal in a frequency domain based on a transmission signal and the channel estimation value of the pilot signal in a time domain and an advance point number with respect to a start position of a fourier transform demodulation window of the pilot signal;

the second channel estimation device is used for carrying out noise reduction on the initial channel estimation value of the pilot signal on a frequency domain so as to obtain a channel estimation value after noise reduction;

the power spectrum determining device is used for determining a power spectrum after noise reduction according to the channel estimation value after noise reduction; and

And the delay spread value determining device is used for determining the maximum delay spread value of the channel according to the power spectrum after noise reduction and the constraint threshold value.

10. The determination system of claim 9, wherein the first channel estimation means comprises:

The signal determining module is used for determining a sending signal and a receiving signal of the pilot signal in a frequency domain according to the sending signal and the channel estimation value of the pilot signal in the time domain and the number of the advance points; and

And the channel estimation module is used for determining the initial channel estimation value according to the transmission signal and the receiving signal of the pilot frequency signal in the frequency domain.

11. The determining system according to claim 10, wherein in the case where the pilot signal is located in the first OFDM symbol of the s-th slot of each frame in the 5G signal, the power spectrum determining means for determining the power spectrum after noise reduction includes:

，

12. The determination system according to claim 11, wherein the delay spread value determining means includes:

The time determining module is used for determining the earliest arrival time and the latest arrival time of the pilot signal according to the power spectrum after noise reduction and the constraint threshold; and

And the delay spread value determining module is used for determining the maximum delay spread value of the channel according to the time difference between the earliest arrival time and the latest arrival time of the pilot signal and the time domain sampling rate of the power spectrum.

13. The determination system of claim 12, wherein the time determination module comprises:

A set determining unit for determining the effective path position set of the pilot signal according to the power spectrum v (n) after noise reduction and the constraint threshold Th by the following formula ：

M is the number of effective diameters; and

14. The determination system of claim 13, wherein the determination system further comprises: threshold determining means for determining the constraint threshold by:

15. The determination system of claim 9, wherein the pilot signal comprises: PRS, CSI-RS, or SSB.

16. The system for determining of claim 9, wherein the means for second channel estimation for denoising the initial channel estimate of the pilot signal in the frequency domain comprises: and adopting CNN to reduce noise of the initial channel estimation value of the pilot signal in the frequency domain.

17. A computer readable storage medium, characterized in that the computer readable storage medium has stored thereon a computer program which, when executed by a processor, implements the method of determining a channel maximum delay spread value according to any of claims 1-8.

18. A chip for executing a computer program which, when executed by said chip, implements the method of determining a channel maximum delay spread value as claimed in any one of claims 1 to 8.

19. A computer program product comprising a computer program which, when executed by a processor, implements the method of determining a channel maximum delay spread value as claimed in any one of claims 1 to 8.