阅读说明：本技术 基于深度学习的小区级rsrp估计方法 (Cell-level RSRP estimation method based on deep learning ) 是由 刘守印 郑毅 王骥 于 2021-10-13 设计创作，主要内容包括：本发明提供了一种基于深度学习的小区级RSRP估计方法,包括以下步骤：根据待估计通信小区的电子地图得到该通信小区的伪电磁环境地图；采用无线传播经验模型,估计该通信小区中各个测量点的RSRP并绘制该通信小区的RSRP预估分布图；将生成的伪电磁环境地图输入给已经完成训练的神经网络模型,获得待估计通信小区的RSRP残差图；根据RSRP预估分布图和RSRP残差图计算得到待估计通信小区信号覆盖区域内的RSRP。本发明在小区层面上进行RSRP估计,有效提高通信小区内RSRP的预测精度。本发明通过训练神经网络模型,在小区层面一次估计整个小区的RSRP,无需预先采集待估计小区的实测RSRP数据,实现了跨小区的RSRP估计。(The invention provides a cell level RSRP estimation method based on deep learning, which comprises the following steps: obtaining a pseudo electromagnetic environment map of a communication cell according to an electronic map of the communication cell to be estimated; estimating the RSRP of each measuring point in the communication cell and drawing an RSRP estimation distribution graph of the communication cell by adopting a wireless propagation empirical model; inputting the generated pseudo electromagnetic environment map to a trained neural network model to obtain an RSRP residual error map of a communication cell to be estimated; and calculating to obtain the RSRP in the signal coverage area of the communication cell to be estimated according to the RSRP estimation distribution graph and the RSRP residual map. The invention carries out RSRP estimation on a cell level, and effectively improves the prediction precision of the RSRP in the communication cell. The invention estimates the RSRP of the whole cell at one time on the cell level by training the neural network model without acquiring the actually measured RSRP data of the cell to be estimated in advance, thereby realizing the cross-cell RSRP estimation.)

1. A cell-level RSRP estimation method based on deep learning is characterized in that: the method comprises the following steps:

s1, obtaining a pseudo electromagnetic environment map of the communication cell according to the electronic map and the base station engineering parameters of the communication cell to be estimated; the pseudo electromagnetic environment map is used for representing the electromagnetic environment of the signal coverage area of the communication cell;

s2, substituting the base station engineering parameters of the communication cell to be estimated into the wireless propagation empirical model, and estimating the RSRP of each measuring point in the communication cell; generating an RSRP estimation distribution diagram of the communication cell according to the estimated RSRP of each measuring point in the communication cell and the electronic map of the communication cell; the RSRP pre-estimation distribution graph is used for representing an RSRP pre-estimation result of a signal coverage area of the communication cell;

S3, taking the pseudo electromagnetic environment map generated in the step S1 as the input of a neural network model which is trained, wherein the neural network model outputs an RSRP residual map of the communication cell to be estimated; the RSRP residual error map is used for reflecting the difference value between the RSRP and real data of a communication cell signal coverage area to be estimated, which is obtained through wireless propagation empirical model estimation;

and S4, calculating to obtain the RSRP in the signal coverage area of the communication cell to be estimated according to the RSRP estimation distribution graph obtained in the step S2 and the RSRP residual graph obtained in the step S3.

2. The deep learning based cell-level RSRP estimation method of claim 1, characterized by: the single sample information of the neural network model training set comprises a pseudo electromagnetic environment map of a certain communication cell as model input and an RSRP residual map of the communication cell as a training label;

calculating according to an electronic map and base station engineering parameters of a certain communication cell to obtain a pseudo electromagnetic environment map of the communication cell;

substituting the base station engineering parameters of the communication cell into a wireless propagation empirical model, and estimating the RSRP of each measuring point in the communication cell; generating an RSRP estimation distribution diagram of the communication cell according to the estimated RSRP of each measuring point in the communication cell and the electronic map of the communication cell; acquiring the RSRP of each actually measured measuring point in the communication cell and generating an RSRP actually measured distribution diagram of the communication cell by combining an electronic map of the communication cell; and generating an RSRP residual error map of the communication cell according to the RSRP pre-estimation distribution map and the RSRP actual measurement distribution map of the communication cell, and using the RSRP residual error map as a neural network model training label.

3. The deep learning based cell level RSRP estimation method of claim 1 or 2, characterized by: the generation method of the pseudo-electromagnetic environment map comprises the following steps:

acquiring an electronic map of a certain communication cell, and rasterizing to obtain an environment height map; converting the environment height map into an electromagnetic environment map according to the base station coordinate information and the base station engineering parameters in the environment height map; and carrying out maximum and minimum normalization processing on the electromagnetic environment map to obtain a pseudo electromagnetic environment map.

4. The deep learning based cell-level RSRP estimation method of claim 2, characterized by: the training process of the neural network model comprises the following steps:

A. constructing a training set;

B. setting a generator: the generator consists of a plurality of layers of neural networks, the input of the generator is a pseudo electromagnetic environment map, and the output of the generator is an RSRP residual error map;

C. setting a discriminator: the discriminator consists of a plurality of layers of neural networks and is used for judging whether the RSRP residual error graph of a single sample is true or not;

D. the generator is confronted and trained by a training set using a discriminator.

5. The deep learning based cell-level RSRP estimation method of claim 4, wherein: the RSRP residual image of a single sample generated by the generator is used for calculating by a discriminator after being masked;

The mask process uses the following formula:

wherein y represents an input RSRP residual diagram of a communication cell corresponding to a single sample; y is^（i，j）Representing the real residual value of an input single sample RSRP residual diagram at a grid (i, j), wherein i belongs to [0, N ], j belongs to [0, M), and N M is the coverage range of the communication cell after the electronic map is subjected to rasterization processing; g^’(x) G (x) is the generator function after the mask processing, which is the original generator function.

6. The deep learning based cell-level RSRP estimation method of claim 1, characterized by: in the step 4, the following formula is adopted to calculate the RSRP of the communication cell；

Wherein G is₀Representing the trained neural network model function, x₀A pseudo electromagnetic environment map representing a communication cell to be estimated;the RSRP estimation distribution diagram of the communication cell to be estimated generated in step S2 is shown.

7. The deep learning based cell-level RSRP estimation method of claim 1, characterized by: if the information of the communication cell to be estimated comprises the actual measurement data of the RSRP of the actual measurement points: generating a new training set and a new testing set according to the measured data, and continuously training the trained neural network model by adopting the new training set and the new testing set; and performing subsequent calculation by adopting the newly trained neural network model as a new trained neural network model.

8. The deep learning based cell-level RSRP estimation method of claim 2, characterized by:

the RSRP estimation distribution diagram is generated by the following steps: acquiring the position of each measuring point in an electronic map of a certain communication cell, estimating the RSRP of each measuring point in the communication cell according to a wireless propagation empirical model, and calibrating the corresponding estimated RSRP at the position of each measuring point in the electronic map to serve as an RSRP estimation distribution map of the communication cell;

the RSRP actual measurement distribution diagram is generated by the following steps: the method comprises the steps of obtaining the position of each measuring point in an electronic map of a certain communication cell, obtaining the RSRP of each measuring point in the communication cell in a manual collection mode, and calibrating the corresponding collected RSRP at the position of each measuring point in the electronic map to serve as an RSRP actual measurement distribution graph of the communication cell.

9. A cell-level RSRP estimation method based on deep learning is characterized in that: the method comprises the following steps:

obtaining a pseudo electromagnetic environment map of the communication cell according to an electronic map and base station engineering parameters of the communication cell to be estimated; the pseudo electromagnetic environment map is used for representing the electromagnetic environment of the signal coverage area of the communication cell;

Taking the generated pseudo electromagnetic environment map as the input of a neural network model which finishes training, wherein the neural network model outputs an RSRP distribution graph of a communication cell to be estimated; the RSRP distribution graph is used for reflecting the RSRP in the signal coverage area of the communication cell to be estimated.

10. The deep learning based cell-level RSRP estimation method of claim 9, characterized by: the single sample information of the neural network model training set comprises a pseudo electromagnetic environment map of a certain communication cell as model input and an RSRP distribution diagram of the communication cell as a training label;

calculating according to an electronic map and base station engineering parameters of a certain communication cell to obtain a pseudo electromagnetic environment map of the communication cell;

acquiring the RSRP of each actually measured measuring point in the communication cell and generating an RSRP actually measured distribution diagram of the communication cell by combining an electronic map of the communication cell; and taking the RSRP actual measurement distribution graph of the communication cell as the RSRP distribution graph of the communication cell as a neural network model training label.

Technical Field

The invention belongs to the technical field of wireless communication, and particularly relates to a cell-level RSRP estimation method based on deep learning.

Background

With the development of wireless communication, the application scenes of the 5G technology in the whole world become more and more. In the process of deploying the 5G network, an operator needs to reasonably select a base station site in a coverage area, so as to meet the communication requirement of a user. However, with the advance of urbanization, new buildings are emerging in a large number, which makes the communication environment more and more complex. Accurate and rapid estimation of Reference Signal Receiving Power (RSRP) in the whole communication cell geographical area under new complex environment is crucial to evaluate the coverage and capacity of emerging 5G wireless networks. Meanwhile, in the whole wireless network planning process, efficient network estimation has very important significance for accurate 5G network deployment. The wireless propagation model is just to study the radio wave propagation characteristics in the target communication coverage area, so as to estimate the RSRP at the signal receiving end. However, as modern society develops rapidly, the radio wave propagation environment is affected by complex and various buildings in cities, and the radio wave propagation environment does not propagate in a single way or path any more, so that complex transmission, scattering, reflection, refraction and the like are generated. Therefore, it is very difficult to establish an accurate wireless propagation model.

Existing wireless propagation models are divided into three categories: the electromagnetic wave propagation law simulation model comprises a statistical-based empirical model, a theoretical model based on an electromagnetic wave propagation law and an improved empirical model. The empirical model is obtained by obtaining a fixed fitting formula, such as Okumura, Cost231-hata, etc., from empirical data. The theoretical model is a model for performing loss calculation in consideration of reflection, diffraction, refraction, and the like in space according to the electromagnetic wave propagation theory, such as a Volcano model. The improved empirical model is a calculation model, such as an SPM model, which can be provided for a more specific scene by introducing more parameters into the fitting formula.

However, there are two drawbacks to the existing wireless propagation model. First, the current RSRP estimation approach is difficult to characterize effectively the electromagnetic environment of radio propagation. This is because the input of the existing wireless propagation model is generally physical characteristics composed of engineering parameters (such as a base station tower height, a transmission frequency, etc.) and map data of a test Point (such as a link distance, a receiving end effective height, etc.), and then RSRP of the receiving end is estimated through Point-to-Point (Point-to-Point) of these discrete physical characteristics. However, physical characteristics used by a point-to-point modeling mode based on a single signal receiving point are difficult to comprehensively sense an electromagnetic environment (such as intra-cell building distribution) of radio propagation, correlation of RSRPs at adjacent receiving points is ignored, and the problem of low accuracy of RSRP estimation in a complex environment is caused. Second, existing wireless propagation models have poor generalization capability across cells. Specifically, when an existing wireless propagation model estimates RSRP of a specific region, a large amount of measured data in the region needs to be collected for fitting and correcting the model, and the corrected model can only be used in a test region, so that a large estimation error is generated when estimation is performed in a new environment, and the estimation effect is poor.

Meanwhile, in the actual propagation model modeling, in order to obtain a more accurate propagation model that meets the actual environment of the target area, a researcher needs to collect a large amount of additional measured data, engineering parameters, and an electronic map to correct the existing propagation model.

Disclosure of Invention

The present invention is directed to solve the above-mentioned drawbacks of the background art, and an object of the present invention is to provide a method for estimating a cell-level RSRP based on deep learning, which effectively improves the prediction accuracy of a Reference Signal Receiving Power (Reference Signal Receiving Power) in a communication cell.

The technical scheme adopted by the invention is as follows: a cell level RSRP (Reference Signal Receiving Power) estimation method based on deep learning comprises the following steps:

s1, obtaining a pseudo electromagnetic environment map of the communication cell according to the electronic map and the base station engineering parameters of the communication cell to be estimated; the pseudo electromagnetic environment map is used for representing the electromagnetic environment of the signal coverage area of the communication cell;

s2, substituting the base station engineering parameters of the communication cell to be estimated into the wireless propagation empirical model, and estimating the RSRP of each measuring point in the communication cell; generating an RSRP estimation distribution diagram of the communication cell according to the estimated RSRP of each measuring point in the communication cell and the electronic map of the communication cell; the RSRP pre-estimation distribution graph is used for representing an RSRP pre-estimation result of a signal coverage area of the communication cell;

S3, taking the pseudo electromagnetic environment map generated in the step S1 as the input of a neural network model which is trained, wherein the neural network model outputs an RSRP residual map of the communication cell to be estimated; the RSRP residual error map is used for reflecting the difference value between the RSRP and real data of a communication cell signal coverage area to be estimated, which is obtained through wireless propagation empirical model estimation;

and S4, calculating to obtain the RSRP in the signal coverage area of the communication cell to be estimated according to the RSRP estimation distribution graph obtained in the step S2 and the RSRP residual graph obtained in the step S3.

In the above technical solution, the single sample information of the neural network model training set includes a pseudo electromagnetic environment map of a certain communication cell as a model input and an RSRP residual map of the communication cell as a training label;

calculating according to an electronic map and base station engineering parameters of a certain communication cell to obtain a pseudo electromagnetic environment map of the communication cell;

substituting the base station engineering parameters of the communication cell into a wireless propagation empirical model, and estimating the RSRP of each measuring point in the communication cell; generating an RSRP estimation distribution diagram of the communication cell according to the estimated RSRP of each measuring point in the communication cell and the electronic map of the communication cell; acquiring the RSRP of each actually measured measuring point in the communication cell and generating an RSRP actually measured distribution diagram of the communication cell by combining an electronic map of the communication cell; and generating an RSRP residual error map of the communication cell according to the RSRP pre-estimation distribution map and the RSRP actual measurement distribution map of the communication cell, and using the RSRP residual error map as a neural network model training label.

In the above technical solution, the training process of the neural network model includes the following steps:

A. constructing a training set;

B. setting a generator: the generator consists of a plurality of layers of neural networks, the input of the generator is a pseudo electromagnetic environment map, and the output of the generator is an RSRP residual error map;

C. setting a discriminator: the discriminator consists of a plurality of layers of neural networks and is used for judging whether the RSRP residual error graph of a single sample is true or not;

D. the generator is confronted and trained by a training set using a discriminator.

In the above technical solution, the objective function of the conditional generation countermeasure network adopted by the countermeasure training is represented as:

wherein, G represents a generator function, D represents a discriminator function, x represents an input single sample pseudo electromagnetic environment map, y represents an RSRP residual error map obtained by calculating a communication cell corresponding to the single sample through a wireless propagation empirical model and measured data, and G (x) represents an RSRP residual error map obtained by calculating the single sample through the generator;

final objective function G of the antagonistic training^*Comprises the following steps:

。

in the above technical solution, the final objective function of the countermeasure training is adjusted by using the loss function in the countermeasure training to reduce the blur of the output image and approximate to the real output, and the adjusted final objective function G of the countermeasure training ^*1Comprises the following steps:

where λ represents the loss weight and l (g) represents the loss function.

In the technical scheme, the RSRP residual diagram of the single sample generated by the generator is used for the calculation of the discriminator after being subjected to masking processing. The mask process uses the following formula:

wherein y represents an input real residual error map of a single sample, namely an RSRP residual error map calculated by a communication cell corresponding to the single sample through a wireless propagation empirical model and measured data; y is^（i，j）Representing the real residual value of the input real residual map of a single sample at a grid (i, j), wherein i belongs to [0, N ], j belongs to [0, M), and N M is the coverage range of the communication cell after the electronic map is subjected to rasterization processing; g^’(x) G (x) is the generator function after the mask processing, which is the original generator function.

In the above technical solution, the following formula is adopted in step 4 to calculate RSRP of the communication cell；

Wherein G is₀Representing the trained neural network model function, x₀A pseudo electromagnetic environment map representing a communication cell to be estimated;the RSRP estimation distribution diagram of the communication cell to be estimated generated in step S2 is shown.

The invention also provides a cell level RSRP estimation method based on deep learning, which comprises the following steps:

obtaining a pseudo electromagnetic environment map of the communication cell according to an electronic map and base station engineering parameters of the communication cell to be estimated; the pseudo electromagnetic environment map is used for representing the electromagnetic environment of the signal coverage area of the communication cell;

Taking the generated pseudo electromagnetic environment map as the input of a neural network model which finishes training, wherein the neural network model outputs an RSRP distribution graph of a communication cell to be estimated; the RSRP distribution graph is used for reflecting the RSRP in the signal coverage area of the communication cell to be estimated.

The single sample information of the neural network model training set comprises a pseudo electromagnetic environment map of a certain communication cell as model input and an RSRP distribution diagram as a training label; wherein the content of the first and second substances,

calculating according to an electronic map and base station engineering parameters of a certain communication cell to obtain a pseudo electromagnetic environment map of the communication cell;

acquiring the RSRP of each actually measured measuring point in the communication cell and generating an RSRP actually measured distribution diagram of the communication cell by combining an electronic map of the communication cell; and taking the RSRP actual measurement distribution graph of the communication cell as the RSRP distribution graph of the communication cell as a neural network model training label.

In the technical scheme, the two methods adopt the same pseudo electromagnetic environment map generation method. The generation method of the pseudo-electromagnetic environment map comprises the following steps:

acquiring an electronic map of a certain communication cell, and rasterizing to obtain an environment height map; converting the environment height map into an electromagnetic environment map according to the base station coordinate information in the environment height map and the base station engineering parameters of the base station; and carrying out maximum and minimum normalization processing on the electromagnetic environment map to obtain a pseudo electromagnetic environment map.

The generation method of the pseudo-electromagnetic environment map specifically comprises the following steps:

acquiring an electronic map of a certain communication cell, and rasterizing to obtain an environment height map; acquiring an altitude height value, a building height value and the height of a signal transmitting tower at the base station in an environment height map according to the coordinate information of the base station, and expressing the altitude height value, the building height value and the height of the signal transmitting tower as the height value at the base station; calculating to obtain an electromagnetic environment map according to the coordinate information of the base station, the height value of the base station, the environment height map and the vertical downtilt of the transmitting antenna of the base station; and carrying out maximum and minimum normalization processing on the electromagnetic environment map to obtain a pseudo electromagnetic environment map with a value range of [0,1 ].

In the above technical solution, the method for generating the pseudo-electromagnetic environment map specifically includes the following steps:

obtaining a map of a certain communication cell and rasterizing the map to obtain an environment height map, wherein the environment height map is represented as h^(i,j)

Wherein i belongs to [0, N), j belongs to [0, M), N M is the coverage area of the communication cell after map rasterization processing, h_altitude ^(i,j)Is the median altitude, h, within the grid (i, j)_building ^(i,j)Is the median height of the building within grid (i, j);

base station is located on grid (p, q), p ∈ [0, N), q ∈ [0, M), height value h at base station _bsThe calculation formula of (2) is as follows:

wherein h is_tower ^(p,q)Is the height of the signal transmission tower at the base station;

the environment height map h is formed by adopting the following formula^(i,j)Conversion into electromagnetic environment map h_e ^(i,j)：

Wherein d is^(i,j)Distance of grid (i, j) from base station, tan beta_vIs the vertical downtilt of the base station transmit antenna;

the electromagnetic environment map h is obtained by adopting the following formula_e(i, j) carrying out maximum and minimum normalization processing to obtain a value range of [0,1]Pseudo electromagnetic environment map h_e ^’(i,j)：

。

In the above technical solution, if the to-be-estimated communication cell information includes measured data of RSRP of a plurality of measured points: generating a new training set and a new testing set according to the measured data, and adopting the new training set and the new testing set to continue training the neural network model after the training is finished; and performing subsequent calculation by adopting the newly trained neural network model as a new trained neural network model.

The RSRP estimation distribution diagram is generated by the following steps: acquiring the position of each measuring point in an electronic map of a certain communication cell, estimating the RSRP of each measuring point in the communication cell according to a wireless propagation empirical model, and calibrating the corresponding estimated RSRP at the position of each measuring point in the electronic map to serve as an RSRP estimation distribution map of the communication cell;

The RSRP actual measurement distribution diagram is generated by the following steps: the method comprises the steps of obtaining the position of each measuring point in an electronic map of a certain communication cell, obtaining the RSRP of each measuring point in the communication cell in a manual collection mode, and calibrating the corresponding collected RSRP at the position of each measuring point in the electronic map to serve as an RSRP actual measurement distribution graph of the communication cell.

The invention has the beneficial effects that:

the invention introduces an empirical formula of wireless signal propagation as a guiding mechanism and provides constraint for the training of the proposed wireless propagation model. According to the invention, a deep learning technology is introduced to assist in sensing the electromagnetic environment of wireless signal propagation, so that a complex new environment is accurately modeled. The invention combines a data-driven machine learning technology with a rule-based signal propagation empirical formula, and provides a wireless propagation model combining data drive and rules. The wireless propagation model provided by the invention effectively guides and constrains the output of the deep learning model by combining the empirical formula of wireless signal propagation and the measured data, thereby accelerating the training speed of the GAN and improving the estimation precision of the RSRP.

Based on the strong fitting capability and generalization capability of the deep learning method, the method adopts a wireless propagation model of a graph-to-graph to carry out accurate cell-level RSRP estimation. Compared with the traditional method for estimating the RSRP at a single receiving point by using a point-to-point wireless propagation model, the method disclosed by the invention realizes the RSRP estimation on the whole geographic coverage area of the communication cell by generating the pseudo-electromagnetic environment map, and effectively improves the prediction accuracy of the RSRP in the communication cell.

The invention adopts the same pre-trained model to carry out simulation prediction on the RSRP of a plurality of different communication cells, thereby realizing cross-cell RSRP estimation. The invention adopts a pre-trained neural network model, and the RSRP simulation work can be realized based on the geographic information of the new cell and the base station engineering parameters before the new cell deploys the base station. The invention can realize accurate RSRP estimation in a complex new cell without real measuring points without acquiring the actual measurement RSRP data of the cell to be measured in advance.

Meanwhile, due to the strong generalization capability of the deep learning model, the model after the countermeasure training is finished is continuously trained by adopting a small amount of partial real-measurement point data, so that the new environment can be quickly modeled and reconstructed, and the application scene of the method is convenient to expand.

Drawings

Fig. 1 is a three-dimensional visualization of a rasterized map of a communication cell in an exemplary embodiment, with desensitized coordinates (in meters) along the x, y axes and the z axis being the altitude of the area plus the building height.

Fig. 2 is a top view of an electronic map of a communication cell in an embodiment, with desensitized coordinates (in meters) in the x and y axes and a minimum resolution of 5 meters by 5 meters, where the squares BS represent the base station locations.

Fig. 3 is a block diagram of a neural network model proposed by the present invention, which shows a model frame of CGANs-based cell-level RSRP estimation with mask processing and residual estimation.

FIG. 4 shows the specific structure of the generator G and the discriminator D in the specific embodiment; wherein CL is a convolution layer and BN is a batch normalization layer.

FIG. 5 is a graph of loss during training for an embodiment; wherein the abscissa represents the epoch, i.e., the number of training rounds (unit: round); the ordinate represents the RMSE, i.e. the root mean square error (unit: dBm).

Fig. 6 is a visual diagram of the communication cell numbered No. 1223001 in the experiment. The upper layer is a three-dimensional graph of the communication cell; the lower layer is vertically projected on the upper layer three-dimensional map, and the x, y and z axes are the coordinates (unit: meter) after desensitization.

Fig. 7 is a diagram of RSRP estimation error probability density function obtained by a conventional SPM method in a communication cell numbered No. 1223001 in an experiment.

Fig. 8 is a graph of RSRP estimation error probability density function of estimation using KNN model in communication cell No. 1223001 in experiment.

Fig. 9 is a graph of RSRP estimation error probability density function of a communication cell numbered No. 1223001 in an experiment, which uses the model proposed by the present invention and uses 30% of data in the communication cell to perform fine-turning estimation.

In fig. 7-9, the abscissa is the RSRP estimation error value (unit: dBm) and the ordinate is the probability density (no unit).

Detailed Description

The invention will be further described in detail with reference to the following drawings and specific examples, which are not intended to limit the invention, but are for clear understanding.

The invention provides a cell level RSRP estimation method based on deep learning, which comprises the following steps:

in the first step, a pseudo electromagnetic environment map of a communication cell is obtained according to an electronic map of the communication cell to be estimated (the content of the electronic map includes but is not limited to building distribution, building height, altitude, ground feature type and the like in the communication cell) and engineering parameters of a base station in the communication cell (the engineering parameters include but is not limited to tower height of the base station, antenna orientation, electronic downward inclination angle, mechanical downward inclination angle, carrier frequency, transmitting power and the like). The pseudo electromagnetic environment map comprises geographic information, building information and engineering parameters of the base station in the signal coverage area of the communication cell.

The generation method of the pseudo-electromagnetic environment map comprises the following steps:

acquiring an electronic map of a certain communication cell, and rasterizing to obtain an environment height map; converting the environment height map into an electromagnetic environment map according to the base station coordinate information in the environment height map and the base station engineering parameters of the base station; and carrying out maximum and minimum normalization processing on the electromagnetic environment map to obtain a pseudo electromagnetic environment map.

The generation method of the pseudo-electromagnetic environment map specifically comprises the following steps:

acquiring an electronic map of a certain communication cell, and rasterizing to obtain an environment height map; acquiring an altitude height value, a building height value and the height of a signal transmitting tower at the base station in an environment height map according to the coordinate information of the base station, and expressing the altitude height value, the building height value and the height of the signal transmitting tower as the height value at the base station; calculating to obtain an electromagnetic environment map according to the coordinate information of the base station, the height value of the base station, the environment height map and the vertical downtilt of the transmitting antenna of the base station; and carrying out maximum and minimum normalization processing on the electromagnetic environment map to obtain a pseudo electromagnetic environment map with a value range of [0,1 ].

The calculation and parameter setting of the electronic map can refer to the methods proposed in Z, Yi, L, Zhiwen, H, Rong, W, Ji, X, Wenwu and L, Shouyin, "Feature Extraction in Reference Signal Received Power Prediction Based on convention Networks," in IEEE Communications Letters, vol 25, No. 6, pp. 1751-.

A specific embodiment of the present invention employs an electronic map of a certain communication cell. The electronic map of the communication cell is rasterized, each grid representing an area of 5m x 5m, as shown in fig. 1, a communication cell covers 64 x 64 grids, i.e. an area covering 320m x 320m, and the arrow in fig. 1 and 2 is the north orientation of the setting. The height value in fig. 1 is calculated by the following formula:

the environment altitude map is represented as h^(i,j)

Wherein N = M =64 is a coverage area of the communication cell after map rasterization processing, h_altitude ^(i,j)Is the median altitude, h, within the grid (i, j)_building ^(i,j)Is the median building height within grid (i, j).

The base station is located at the grid (0,32), the height value h at the base station_bsThe calculation formula of (2) is as follows:

wherein h is_tower ^(0,32)Is the height of the signal transmission tower at the base station; the parameters in the electronic map can be obtained through a building database of the region, and also can be obtained through an open source API of an OpenStreetMap or Google map.

The environmental altitude map is further transformed into a pseudo electromagnetic environment map, taking into account that the propagation of the radio is affected by the engineering parameters of the base station. Firstly, the environment height map h is mapped by adopting the following formula^(i,j)Conversion into electromagnetic environment map h_e ^(i,j)：

Wherein d is^(i,j)Distance of grid (i, j) from base station, tan beta _vThe vertical downtilt angle of the base station transmit antenna.

The electromagnetic environment map h is obtained by adopting the following formula_e(i, j) carrying out maximum and minimum Normalization (Min-max Normalization) processing to obtain a value range of [0,1]Pseudo electromagnetic environment map h_e ^’(i,j)

。

Substituting the base station engineering parameters of the communication cell to be estimated into a wireless propagation empirical model (such as COST231-Hata, SPM and the like) to estimate the RSRP of each measuring point in the communication cell; generating an RSRP estimation distribution diagram of the communication cell according to the estimated RSRP of each measuring point in the communication cell and the electronic map of the communication cell; the RSRP estimation distribution graph is used for representing an RSRP estimation result of a signal coverage area of the communication cell.

Thirdly, the pseudo electromagnetic environment map generated in the first step is used as the input of a neural network model which is trained, and the neural network model outputs an RSRP residual map of a communication cell to be estimated; the RSRP residual error map is used for reflecting the difference value between the RSRP and the real data of the signal coverage area of the communication cell to be estimated, which is obtained through wireless propagation empirical model estimation.

The training process of the neural network model comprises the following steps:

A. constructing a training set and a testing set, wherein single sample information of the training set and the testing set of the neural network model comprises a pseudo electromagnetic environment map and an RSRP residual map of a certain communication cell;

Calculating a pseudo electromagnetic environment map of a certain communication cell according to an electronic map and base station engineering parameters of the communication cell, and using the pseudo electromagnetic environment map as an input of a neural network model;

substituting the base station engineering parameters of the communication cell into a wireless propagation empirical model, and estimating the RSRP of each measuring point in the communication cell; generating an RSRP estimation distribution diagram of the communication cell according to the estimated RSRP of each measuring point in the communication cell and the electronic map of the communication cell; acquiring the RSRP of each actually measured measuring point in the communication cell and generating an RSRP actually measured distribution diagram of the communication cell by combining an electronic map of the communication cell; and generating an RSRP residual error map of the communication cell according to the RSRP pre-estimation distribution map and the RSRP actual measurement distribution map of the communication cell, and using the RSRP residual error map as a neural network model training/testing label.

The RSRP estimation distribution diagram is generated by the following steps: acquiring the position of each measuring point in an electronic map of a certain communication cell, estimating the RSRP of each measuring point in the communication cell according to a wireless propagation empirical model, and calibrating the corresponding estimated RSRP at the position of each measuring point in the electronic map to serve as an RSRP estimation distribution map of the communication cell;

The RSRP actual measurement distribution diagram is generated by the following steps: the method comprises the steps of obtaining the position of each measuring point in an electronic map of a certain communication cell, obtaining the RSRP of each measuring point in the communication cell in a manual collection mode, and calibrating the corresponding collected RSRP at the position of each measuring point in the electronic map to serve as an RSRP actual measurement distribution graph of the communication cell.

B. Setting a generator: the generator consists of a plurality of layers of neural networks, the input of the generator is a pseudo electromagnetic environment map, and the output of the generator is an RSRP residual error map.

C. Setting a discriminator: the discriminator consists of a plurality of layers of neural networks and is used for judging whether the RSRP residual image of a single sample is true or not.

D. Adopting a discriminator to carry out countermeasure training on the generator through a training set; and testing the generator after the countermeasure training through the test set.

The countermeasure network of the generator G and the discriminator D in the invention is a wireless propagation model based on the condition GANs, and the aim of the countermeasure network is to learn the mapping from a pseudo electromagnetic environment map x in a communication cell to the residual error y between the measured RSRP (Reference Signal Receiving Power) and the estimation result of the traditional wireless propagation model. The overall framework of the model is shown in figure 3. The input x of the model is a preprocessed pseudo electromagnetic environment map, and the generator G converts the input x into G' (x), namely an estimated RSRP residual map. Then, the estimated residual error map G (x) is obtained after the treatment of the invalid value Mask on G' (x). In order to ensure that the generated estimated residual map matrix is as true as possible, a discriminator D is designed to determine whether the input matrix (generated g (x)) or the true residual map y is true. The generator G output can be approximated to the real image by the antagonistic training of the generator G and the discriminator D.

In the image processing, because the value of the pixel point in the image is restricted in the range of [0,255], the pixel value is easy to be normalized. However, the range of RSRP in a communication cell is affected by factors such as engineering parameters of a base station and complexity of a propagation environment, and important RSRP range information is lost when the actual RSRP is directly converted into a real RSRP image for normalization according to a map position.

In order to solve the above problems, the present invention proposes to introduce a conventional empirical wireless propagation model into a CGAN-based wireless propagation model. RSRP estimation results by a manual empirical formula provide rough range information for RSRP. As shown in fig. 3, the residual error of the Fitting Model estimation result (Fitting Model Prediction) is obtained by obtaining the RSRP real value (Ground true) in the sample communication cell and Fitting the measured data with the conventional wireless propagation empirical Model, and the output of the deep learning Model (i.e., generator G) is constrained. The true residual map y is calculated as follows:

wherein the content of the first and second substances,to be the RSRP measurement profile,and estimating a distribution diagram for RSRP.

In the field of image translation, images to be converted are often complete pictures. However, it is difficult to acquire RSRP of all points in a communication cell during actual measurement of data due to factors such as terrain or manpower. This results in RSRP images of a communication cell containing a large number of invalid values. In order to avoid interference of the invalid value on model training, masking processing is required, and the masking processing is calculated by using the following formula:

Wherein y represents an input real residual error map of a single sample, namely an RSRP residual error map obtained by calculating a wireless propagation empirical model and measured data of a corresponding communication cell; y is^（i，j）Representing the real residual value of the input real residual map of a single sample at a grid (i, j), wherein i belongs to [0, N ], j belongs to [0, M), and N M is the coverage range of the communication cell after map rasterization processing; g^’(x) G (x) is the generator function after the mask processing, which is the original generator function. If the image is a region on the grid (i, j) that needs to be masked, the masked imageThe image at (a) is set to 0.

The specific structures of the generator G (Generator) and the discriminator D (discriminator) are shown in FIG. 4. For the Generator, since much information is shared between the input and the output, if a general convolutional neural network structure is used, each layer is loaded with all information, and thus the neural network is easy to be in error. Thus, U-Net is used for load shedding. U-Net is a symmetric Encoder-Decoder structure that concatenates the ith downsampled layer to the (n-i) th upsampled layer. This is done because the image sizes of the ith and nth-i layers are consistent and they can be considered to carry similar information. For the Discriminator, the features of the input image are extracted by a three-layer down-sampling layer structure, and the output is the judgment result of the input image.

Wherein, the down-sampling layer is composed of Convolution Layer (CL) with convolution kernel [4,4], Batch Normalization (BN) and activation function of Leaky Rectified Linear Units (Leaky ReLu). The upsampling layer consists of the activation functions of the deconvolution layer (CTL), BN, Dropout, and Leaky ReLu. The purpose of convolution operation is to extract different features of the input, and multi-layer convolution layers can iteratively extract more complex features from low-level features. BN is used for improving the stability of input distribution of each layer and Reducing ICS (Interval covariance Shift) of a neural Network.

The conditions adopted by the countermeasure training generate an objective function of the countermeasure network expressed as:

wherein G represents a generator function, D represents a discriminator function, x represents an input pseudo electromagnetic environment map of a single sample, y represents a real residual error map of the single sample, and G (x) represents a calculated residual error map calculated by the generator of the single sample;

where G tries to minimize this goal, and D fighting it tries to maximize it, the final goal of the fight trainingFunction G^*Comprises the following steps:

the final objective function of the countermeasure training is adjusted by using a loss function (such as L1 distance) in the countermeasure training to reduce the blurring of the output image and approximate the real output, and the adjusted final objective function G of the countermeasure training ^*1Comprises the following steps:

wherein the content of the first and second substances,；

λ is the loss weight. The L1 distance is also known as the manhattan distance.

During the off-line training period, the present embodiment adopts the standard optimization method of CGAN. The parameters of the generator G and the discriminator D are updated in each training step by alternately calculating the gradients of the generator G and the discriminator D. For the learning rate in adaptive decay training, ADAM algorithms are applied in the proposed model. During training, the hyper-parameter collapsed pix2pix model and the loss weight are used, the initial learning rate is, the momentum parameter is beta₁=0.5,β₂=0.99。

And fourthly, calculating to obtain the RSRP in the signal coverage area of the communication cell to be estimated according to the RSRP estimation distribution diagram obtained in the second step and the RSRP residual diagram obtained in the third step.

During online prediction, the trained neural network model will be deployed alone for predicting RSRP distribution in a new communication cell, running the generator network in exactly the same way as the training phase. The RSRP estimate of a certain communication cell predicted online may be represented by the following equation:

wherein G is₀Representing the trained neural network model function, x₀A pseudo electromagnetic environment map representing a communication cell to be estimated;the RSRP estimation distribution diagram of the communication cell to be estimated is shown.

The invention also provides a cell level RSRP estimation method based on deep learning, which comprises the following steps:

obtaining a pseudo electromagnetic environment map of the communication cell according to an electronic map and base station engineering parameters of the communication cell to be estimated; the pseudo electromagnetic environment map is used for representing the electromagnetic environment of the signal coverage area of the communication cell;

taking the generated pseudo electromagnetic environment map as the input of a neural network model which finishes training, wherein the neural network model outputs an RSRP distribution graph of a communication cell to be estimated; the RSRP distribution graph is used for reflecting the RSRP in the signal coverage area of the communication cell to be estimated.

The single sample information of the neural network model training set comprises a pseudo electromagnetic environment map of a certain communication cell as model input and an RSRP distribution diagram as a training label; wherein the content of the first and second substances,

calculating according to an electronic map and base station engineering parameters of a certain communication cell to obtain a pseudo electromagnetic environment map of the communication cell;

acquiring the RSRP of each actually measured measuring point in the communication cell and generating an RSRP actually measured distribution diagram of the communication cell by combining an electronic map of the communication cell; and taking the RSRP actual measurement distribution graph of the communication cell as the RSRP distribution graph of the communication cell as a neural network model training label.

The beneficial effects of the first method proposed by the present invention are verified by using specific experimental data.

The experimental data used in this experiment was open source RSRP measured data provided by hua shi corporation. The urban communication system comprises 415,244 receiving end real measurement points in 181 urban communication cells, and an average cell comprises 2294 real measurement points. Each communication cell has been pre-processed into a 64 x 64 grid, each grid representing an area of 5m x 5m, i.e. it is assumed that the effective coverage area of the base station of each cell is 320m x 320 m. The measurement parameters are shown in the following table:

in order to better test the performance of the proposed model, the RSRP measured measurement data set randomly divides 181 cells into a training set consisting of 150 cells and a test set consisting of 31 cells on a communication cell level. The proposed model will be trained offline on a training set, and then the trained model will predict RSRP of the test set online.

The experiment mainly uses RMSE and MAPE to measure the estimated performance of the proposed model, and the formula is as follows:

wherein n is the number of all actual measuring points, S_trueiThe measured value of the RSRP of the ith measured point,and the RSRP estimated value is predicted online by the model provided by the invention for the ith real-measuring point.

Furthermore, if the received signal power level of the coverage area can be effectively identified in the process of prediction, the method can better help operators to accurately plan and optimize the network. Therefore, the accuracy of signal coverage level identification is also a very valuable evaluation index. According to the signal strength level specification divided by china mobile, the signal is divided into 5 levels, which are shown in the following table:

the RSRP of 5 levels can be considered as 5 different classes, and the present experiment introduces the accuracy, precision and F1Score of the multi-classification problem to verify the received signal power level performance of the coverage area identified by the proposed model.

As shown in the following table, TP indicates that the sample is actually a positive sample and the model predicts that the sample is a positive sample; FN means that the actual sample is positive, and the model is predicted to be negative; FP means that the actual sample is a negative sample and the model is predicted to be a positive sample; TN means actually negative, model predicts negative:

the calculation formulas for accuracy accuracycacy, precision, Recall, and F1Score are as follows:

。

in order to verify the performance of the model proposed by calculating the residual constraint by using the traditional wireless propagation empirical model, the original pix2pix model is used as baseline to be compared with the model proposed by the invention. The original pix2pix model directly uses the measured RSRP map instead of the true residual map y in fig. 3. The loss curve during training is shown in fig. 5, and the model proposed by the present invention converges to a lower loss more quickly during training. Experimental results show that the artificial experience formula is helpful for improving the performance of the proposed model.

In order to verify the generalization ability of the model provided by the invention in a new communication cell, the test set compares the prediction performances of the neural network model (hereinafter referred to as the model) provided by the invention and the traditional wireless propagation models Cost231-Hata, SPM and the SPM fitting model using the training set correction coefficients. The corrected SPM fitting model can be expressed as:

。

meanwhile, commonly used machine learning algorithms such as Linear Regression (LR) k-nearest neighbor (KNN) and Random Forest Regression (RFR) are also trained to predict RSRP of new cells. Experiments show that the RSRP prediction accuracy of the model provided by the invention in a new cell is higher than that of a point-to-point based machine learning model. To visually observe the predictive power of the proposed model, a cell No.1223001, which contained 2361 actual test points, was randomly selected from the test set in this experiment. By comparing the prediction results of the conventional SPM, as shown in the following table, it is verified that the model (deployed model) proposed by the present invention has good cross-cell generalization capability:

if the information of the communication cell to be estimated comprises the actual measurement data of the RSRP of the actual measurement points: generating a new training set and a new testing set according to the actual measurement points and the actual measurement data corresponding to the actual measurement points, and adopting the new training set and the new testing set to continue the counter training of the generator which finishes the counter training; the third step is performed using the neural network model with the training countered completed.

The experiment assumes a scenario that when a new communication cell contains a certain amount of measured data, a wireless propagation model is established to predict the RSRP of the whole cell. The real test points of the communication cell No.1223001 are divided into a training set and a test set in a 7:3 ratio. LR, KNN and RFR machine learning models are respectively trained by using training sets in a single communication cell, and then RSRP in the single cell is predicted by the trained machine learning models. Similarly, the training set fine-tuning model is used to predict the RSRP in a single cell, and then the fine-tuning model (advanced model (FT)) is used to predict RSRP in a single cell, and the performance index is shown in the following table:

experimental results show that in the machine learning method, the highest accuracy of RSRP prediction in a single cell is RFR. By comparing the proposed model with RFR, the RMSE of the RSRP predicted by the proposed model is reduced by 1.12dBm compared with RFR, and F1Score reaches 84.1, which is improved by 10.3 compared with RFR.

For a more intuitive observation, error diagrams of the different models are shown in fig. 7-9. The RSRP prediction performance of the model not subjected to fine-tuning provided by the invention can be close to a machine learning algorithm trained by using real measuring points of the same cell, and the model subjected to the real measuring points fine-tuning of the same cell can effectively reduce the prediction error of the RSRP, so that the RSRP in a communication cell can be predicted more accurately.

This experiment shows the effect of including different numbers of actual measurement points in a communication cell to define the model proposed by the-tuning on the model predictive performance. As shown in the following table, with the increase of the actual measurement points added into the training set, the proposed model can "see" more actual measurement data information, and the RSRP is predicted more accurately. Wherein 1-9,3-7 and the like represent the proportion of the measured point data and the original training set as training samples:

those not described in detail in this specification are within the skill of the art.