CN104679957A - Method for electromagnetic simulation of different error maps with ray tracing algorithm - Google Patents

Abstract

The invention discloses a method for electromagnetic simulation of different error maps with a ray tracing algorithm, which mainly solves the problem of the undefined influence degree of different types of map error factors in geometric environmental information on an existing ray tracing model predicting result. The method is implemented by the following steps: (1) obtaining a required digital map corresponding to the outdoor micro-area environment; (2) respectively generating a plurality of building top offset error maps and wall translation error maps on the basis of the obtained map; (3) performing radio wave propagation simulation prediction on the original digital map and the error maps by adopting a ray tracing model, so as to obtain a mean value and a root-mean-square value of path losses of the top offset error maps and the wall translation error maps as well as the original digital map at each test point. According to the method, the influence degree of the different types of error factors in the geometric information on the precision of the ray tracing predicting result can be analyzed through the mean value and the root-mean-square value which are obtained through simulation, and reference is provided for radio wave propagation and channel prediction in an outdoor micro-area scene.

Description

With ray tracing algorithm, different error maps is carried out to the method for Electromagnetic Simulation

Technical field

The invention belongs to Electromagnetic Simulation electric powder prediction under complex environment, relate generally to the radio wave propagation numerical simulation under the scene of outdoor Microcell, can be used for the precision of prediction improving ray tracing models, for the network planning provides theoretical foundation.

Background technology

Mobile communication, as a kind of communication mode of wireless communication field most development prospect, occurs from the 1980s, then puts into effect to forth generation mobile communication technology instantly, and its development only experienced for three times more than ten years.Performance and the radio propagation environment of mobile radio communications system are closely related.For meeting people to the active demand improving cell communication systems capacity, in numerous solution, there has been proposed this concept of Microcell.Telecom operators are in order to choose the demands such as better antenna for base station decorating position, all need to carry out the measures such as network planning network optimization before network erection, research about radio waves propagation model just can be the network planning and provides theoretical foundation, but, the degree of accuracy of propagation forecast model also can impact quorum sensing inhibitor radius of society estimation etc., so, obtain more accurate propagation forecast model and just become extremely important.

In last decade, ray trace has become the main method that modeling is propagated in research Microcell.Two the topmost problems relevant to propagation model are degree of accuracy and the susceptibility of model.And the degree of accuracy of this characteristic of Tracing Technology and the database of describe environment information is closely related, when adopting ray tracing algorithm to predict the radio wave propagation in the outer microcell environment of given chamber and coverage condition, first need the geological information obtaining respective environment, and the precision of the accuracy of geological information to algorithm predicts result is most important.Here the environmental information of indication mainly comprises the geological information of buildings, and that is, under adopting ray tracing algorithm to carry out Microcell, predicted city scene during radio wave propagation situation, environment geological information is one of most important factor affecting model accuracy.A kind of feasible method obtaining environment geological information is read by city digital map, and now, the accuracy of city digital map used just can become the key factor affecting the precision that ray tracing models predicts the outcome.

Existing about environment geological information in the research of ray trace algorithm predicts Influence on test result, only for map medial error size situation research is affected on simulation accuracy, but not have a clear understanding of in environment geological information different error component to the intensity of ray trace algorithm simulating Influence on test result, therefore cause the precision of ray tracing algorithm Electromagnetic Simulation result not meet the demands, guidance cannot be provided for the network planning.

Summary of the invention

The object of the invention is to the deficiency for above-mentioned prior art, a kind of ray tracing algorithm carries out Electromagnetic Simulation method to different error maps is proposed, to reduce the deviation of simulation result and measured result, improve the degree of accuracy of ray tracing models simulation result, for the network planning provides theoretical direction.

Realize the technical scheme of the object of the invention, comprise the steps:

(1) the respective digital map of the outdoor microcell environment in the town needing to carry out simulation and prediction is obtained;

(2) gained numerical map is processed, produces many groups respectively and meet the dissimilar error maps of two kinds of specified conditions:

(2a) buildings summit is made to offset, and each apex offset amount is identical, deviation angle meets equally distributed error maps, generate the buildings apex offset error maps that 5 groups of side-play amounts are respectively 0.5m, 1.0m, 1.5m, 2.0m and 2.5m, often organize apex offset error maps and comprise again 25 width error maps, this 25 width error maps has identical side-play amount;

(2b) building walls is made in the direction of its normal to interior of building or outside translation, and keep each wall of buildings to move towards constant, generate the building walls translation error map that 5 groups of translational movements are respectively 0.5m, 1.0m, 1.5m, 2.0m and 2.5m, with similar in step (2a), often organize wall translation error map and comprise again 25 width error maps, this 25 width error maps has identical side-play amount;

(3) in region shown in the numerical map of step (1) gained, be that test point is outside the building chosen in side in interval with 5m, and adopt ray tracing models to carry out radio wave propagation emulation, calculate the path loss values P at each test point place of this numerical map _i(test point i);

(4) amount in region shown in 250 width error maps at 10 groups of step (2) gained, be that test point is outside the building chosen in side in interval with 5m, adopt ray tracing models to carry out radio wave propagation emulation, calculate the path loss values P at each test point place of this error maps _{ij ε};

Wherein, i represents test point; The value of j be 1 or 2, j=1 represent that map error type is the first kind, i.e. apex offset error, j=2 then represents that map error type is the second type, i.e. building walls translation error; ε then represents the side-play amount of often kind of error maps.

(5) step (4) gained 10 groups is amounted to the path loss values P at each test point place in 250 width error maps _{ij ε}respectively with the path loss values P at step (3) gained numerical map same test point place _idiffer from, these differences corresponding to every width error maps are averaged and root-mean-square value respectively, obtains 10 groups of data, often organize data and comprise 25 averages and 25 root-mean-square values; Again 25 averages often organized in data and 25 root-mean-square values are averaging respectively, obtain the average of 10 averages and the average of 10 root-mean-square values.

Tool of the present invention has the following advantages:

First, the present invention generates buildings apex offset error maps and building walls translation error map on the basis of existing digit map, to compare the chaotic unclear situation of various error component in numerical map in the past, distinguishing the different error components in error maps, having provided convenience for analyzing the impact of different error component on simulation result.

Second, the present invention adopts ray tracing models to emulate in a large number respectively two kinds of error maps, and simulation result corresponding to existing digit map compares, specify that different error component affects intensity to simulation result precision, reduce the deviation of simulation result and measured result, for the degree of accuracy improving ray tracing models simulation result provides guidance.

Accompanying drawing explanation

Fig. 1 is realization flow figure of the present invention;

Fig. 2 is the buildings storage mode schematic diagram used in the present invention;

Fig. 3 is the buildings geological information storage format schematic diagram used in the present invention;

Fig. 4 is the apex offset error maps schematic diagram in the present invention;

Fig. 5 is the wall translation error map schematic diagram in the present invention;

Fig. 6 is urban centre, the Ottawa map that the present invention emulates use;

Fig. 7 is for urban centre, Ottawa map when different transmit antennas position, adopts the present invention to carry out acquired results figure after radio wave propagation emulation;

Embodiment

With reference to Fig. 1, specific implementation step of the present invention is as follows:

Step one: the numerical map reading the outdoor Microcell scene of required emulation.

The numerical map of the outdoor Microcell scene that this example reads is urban centre, Ottawa map, is marked with buildings in this map;

Stored according to counter-clockwise on buildings surface level summit, buildings storage mode as shown in Figure 2;

When storing buildings summit, many storages point, last point is overlapped with first point, and form closing face, to meet the data structure of ray tracing models, the geological information storage format on this buildings summit as shown in Figure 3.

Step 2: process gained numerical map, produces many group apex offset error maps and building walls translation error map respectively.

(2a) many group apex offset error maps are produced:

(2a1) based on numerical map shown in Fig. 3, to wherein representing that each summit two-dimensional coordinate information of each contour of building adds offset information, make each apex offset amplitude be 0.5m, offset direction within the scope of 0 ~ 2 π according to being uniformly distributed random value, as shown in Figure 4;

(2a2) repeat step (2a1), amount to the identical but error maps that offset direction is different of generation 25 width apex offset amplitude, be designated as first group of summit error maps;

(2a3) step (2a1)-(2a2) is repeated successively, generate the four grouping error maps that skew amplitude is respectively 1.0m, 1.5m, 2.0m and 2.5m and offset direction random value within the scope of 0 ~ 2 π, be designated as respectively second, third, the 4th, the 5th grouping error map, all comprise the error maps that 25 width apex offset amplitudes are identical in every grouping error map;

(2b) many group building walls translation error maps are produced:

(2b1) based on numerical map shown in Fig. 3, adjacent two vertex point coordinate information in each buildings are read successively from map file, the straight-line equation at the line segment place representing its wall is obtained by this two point coordinate, determine the straight-line equation of each wall successively, afterwards translation process is done to straight-line equation, translation amplitude is 0.5m, produces new straight-line equation; Find intersection process is done successively to each bar straight line after translation, is met the error maps of requirement, as shown in Figure 5;

(2b2) repeat step (2b1), total generation 25 width building translation amplitude is identical but translation direction prolongs the error maps of the inside or outside random selecting of wall normal, and is designated as first group of building walls translation error map;

(2b3) step (2b1)-(2b2) is repeated successively, generate the four grouping error maps that wall translation amplitude is respectively 1.0m, 1.5m, 2.0m and 2.5m, be designated as respectively second, third, the 4th, the 5th grouping error map, include the error maps that 25 width wall translation amplitudes are identical in every grouping error map.

Step 3: the path loss values P calculating each test point place in numerical map _i.

In the numerical map of step one gained, be that test point is outside the building chosen in side in interval with 5m; Position of transmitting antenna, dual-mode antenna height, test point position are set, and given dual-mode antenna type, transmitting antenna power, emitting antenna frequency, these parameters of polarization mode, adopt ray tracing models to emulate, calculate the path loss values P at each test point place in this numerical map _i:

$P_i=201g|\frac{\mathrm{\λ}}{4\mathrm{\π}{G}_t{G}_r}\·\frac{E_i}{E_0}|\left(\mathrm{dB}\right)$

Wherein, λ is electric wave wavelength, G _tfor transmitter antenna gain (dBi), G _rfor receiving antenna gain, E _ithe electric field strength at test point i place in step (1) gained numerical map, E ₀for launching site place electric field strength.

Step 4: the path loss values P at each test point place of error of calculation map _{ij ε}.

Amount in region shown in 250 width width two class error maps step 2 gained 10 groups, be that test point is outside the building chosen in side in interval with 5m, other optimum configurations are identical with optimum configurations each in step 3, adopt ray tracing models to emulate, calculate the path loss values P at each test point place of this error maps _{ij ε}:

$P_{\mathrm{ij\ϵ}}=201g|\frac{\mathrm{\λ}}{4\mathrm{\π}{G}_t{G}_r}\·\frac{E_{\mathrm{ij\ϵ}}}{E_0}|\left(\mathrm{dB}\right)$

Wherein, λ is electric wave wavelength, G _tfor transmitter antenna gain (dBi), G _rfor receiving antenna gain, E _{ij ε}the electric field strength to be side-play amount be test point i place in the jth class error maps of ε, E ₀for launching site place electric field strength.

Step 5: each acceptance point place path loss data in error maps is taken statistics process.

(5a) the path loss result that path loss result corresponding for each width error maps and primary standard map basis obtain is compared, obtain the path-loss difference value ERR that each width error maps is corresponding _p:

ERR _p＝P _ijε-P _i

Wherein, P _irepresent utilizes ray tracing models to emulate the path loss values obtained, P in standard map _{ij ε}represent in error maps according to the path loss values of ray tracing models gained;

(5b) the path-loss difference value information of 25 width error maps in the every grouping error map obtained step 2 takes statistics process, calculates the average of each test point place path-loss difference value in every width map respectively and root-mean-square value in often kind of error amount situation, the average of 25 path-loss difference value is obtained at often kind of error pattern and root-mean-square value

(5c) step (5b) gained is often planted to the average of 25 path-loss difference value that error pattern obtains in often kind of error amount situation be averaging, obtain mean of mean step (5b) gained is often planted to the root-mean-square value of 25 path-loss difference value that error pattern obtains in often kind of error amount situation be averaging, obtain the mean value of root-mean-square value

Effect of the present invention can be further illustrated by following experiment:

1. experiment simulation condition

The CPU of simulation computer is Intel's Duo (Core) i3, and dominant frequency 2.93GHz, inside saves as 4GB.Windows 7 system is installed Visual Studio 2010 translation and compiling environment.

2. experiment content and interpretation of result

Select Microcell, city scene map as shown in Figure 6, use ray tracing algorithm to emulate path loss.Position of transmitting antenna choose respectively as shown in six asterisks in Fig. 6, wherein T1 and T4 representative emitting antenna is positioned on the arterial street of city, T2 and T5 is typical right-angled intersection, T3 and T6 is then positioned at city open area.

Dual-mode antenna all adopts vertical single-polarized antenna, and wherein emitting antenna is 8.5m apart from floor level, and radiation power is 10w, and receiving antenna is 3.65m apart from floor level, and wave frequency is 2GHz, and the area size carrying out emulating is 935 × 600m.The relative dielectric constant arranging buildings is ε _r=9, conductivity is σ=0.1S/m; Ground relative dielectric constant is ε _r=15, conductivity is σ=7S/m.

According to above-mentioned Setup Experiments, utilize emulation mode of the present invention to obtain six different transmit antennas position Tx1, the ray tracing models that Tx2, Tx3, Tx4, Tx5, Tx6 are corresponding, result as shown in Figure 7, wherein:

When Fig. 7 (a) represents that emitting antenna is in Tx1 position, between error maps and original map, the average of path-loss difference value and root-mean-square value are with the situation of change of different error amount;

When Fig. 7 (b) represents that emitting antenna is in Tx2 position, between error maps and original map, the average of path-loss difference value and root-mean-square value are with the situation of change of different error amount;

When Fig. 7 (c) represents that emitting antenna is in Tx3 position, between error maps and original map, the average of path-loss difference value and root-mean-square value are with the situation of change of different error amount;

When Fig. 7 (d) represents that emitting antenna is in Tx4 position, between error maps and original map, the average of path-loss difference value and root-mean-square value are with the situation of change of different error amount;

When Fig. 7 (e) represents that emitting antenna is in Tx5 position, between error maps and original map, the average of path-loss difference value and root-mean-square value are with the situation of change of different error amount;

When Fig. 7 (f) represents that emitting antenna is in Tx6 position, between error maps and original map, the average of path-loss difference value and root-mean-square value are with the situation of change of different error amount.

Following 3 points can be found out from above six width figure:

First, no matter be apex offset error maps, or wall translation error map, when the side-play amount of summit or wall increases, corresponding path-loss difference value also increases thereupon, can obtain thus, the accuracy of map error of acquisition is larger, adopts ray tracing algorithm gained path loss prediction result to get over out of true;

Second, the average of the path-loss difference value of buildings apex offset error and root-mean-square value are all less than average and the root-mean-square value of the path-loss difference value corresponding to building walls translation error, illustrate that the impact of apex offset error ratio wall translation error on path loss prediction is larger;

3rd, described Tx1 and Tx4 is positioned on the arterial street in city, Tx2 and Tx5 is positioned at cross crossing, Tx3 and Tx6 is then positioned at open area, between the route loss simulation result that the emitting antenna in identical type geographic position is corresponding, difference is obvious, and this illustrates and adopts ray tracing algorithm predicted path loss value also by the impact of emitting antenna present position.

To sum up, the present invention can obtain different error component affects situation to ray trace algorithm predicts result precision, the problem that the precision of prediction that can solve ray tracing algorithm affects by error maps, thus to offer reference meaning for radio wave propagation under the scene of outdoor Microcell and channel estimating.

More than describing is only example of the present invention; obviously for the professional in this area; after having understood content of the present invention and principle; can carry out the various correction in form and in details and change, but these corrections based on inventive concept and change are still within claims of the present invention.

Claims (5)

1. with ray tracing algorithm, different error maps is carried out to a method for Electromagnetic Simulation, comprise the steps:

(1) the respective digital map of the outdoor microcell environment in the town needing to carry out simulation and prediction is obtained;

(2) gained numerical map is processed, produces many groups respectively and meet the dissimilar error maps of two kinds of specified conditions:

(2a) buildings summit is made to offset, and each apex offset amount is identical, deviation angle meets equally distributed error maps, generate the buildings apex offset error maps that 5 groups of side-play amounts are respectively 0.5m, 1.0m, 1.5m, 2.0m and 2.5m, often organize apex offset error maps and comprise again 25 width error maps, this 25 width error maps has identical side-play amount;

(2b) building walls is made in the direction of its normal to interior of building or outside translation, and keep each wall of buildings to move towards constant, generate the building walls translation error map that 5 groups of translational movements are respectively 0.5m, 1.0m, 1.5m, 2.0m and 2.5m, with similar in step (2a), often organize wall translation error map and comprise again 25 width error maps, this 25 width error maps has identical side-play amount;

(3) in region shown in the numerical map of step (1) gained, be that test point is outside the building chosen in side in interval with 5m, and adopt ray tracing models to carry out radio wave propagation emulation, calculate the path loss values P at each test point place of this numerical map _i;

(4) amount in region shown in 250 width error maps at 10 groups of step (2) gained, be that test point is outside the building chosen in side in interval with 5m, adopt ray tracing models to carry out radio wave propagation emulation, calculate the path loss values P at each test point place of this error maps _{ij ε};

(5) step (4) gained 10 groups is amounted to the path loss values P at each test point place in 250 width error maps _{ij ε}respectively with the path loss values P at step (3) gained numerical map same test point place _idiffer from, these differences corresponding to every width error maps are averaged and root-mean-square value respectively, obtains 10 groups of data, often organize data and comprise 25 averages and 25 root-mean-square values; Again 25 averages often organized in data and 25 root-mean-square values are averaging respectively, obtain the average of 10 averages and the average of 10 root-mean-square values.

2. ray tracing algorithm according to claim 1 carries out the method for Electromagnetic Simulation to different error maps, it is characterized in that: the buildings summit that makes described in step (2a) offsets, based on the middle numerical map obtained of step (1), therefrom read the summit two-dimensional coordinate representing contour of building successively, offset information is added to it, its apex offset amplitude is fixed, deviation angle in 0 ~ 2 π according to being uniformly distributed random value.

3. ray tracing algorithm according to claim 1 carries out the method for Electromagnetic Simulation to different error maps, it is characterized in that: make building walls translation described in step (2b), carries out as follows:

(2b1), in the numerical map obtained in step (1), the coordinate information of two adjacent vertexs representing each contour of building is read successively;

(2b2) form straight-line equation with two adjacent vertexs, and this straight-line equation translation is produced new straight-line equation;

(2b3) to new straight-line equation find intersection respectively, obtain each intersecting point coordinate, gained intersecting point coordinate is the apex coordinate representing each contour of building in wall translation error map.

4. ray tracing algorithm according to claim 1 carries out the method for Electromagnetic Simulation to different error maps, it is characterized in that: the calculating path loss value P described in step (3) _i, by following formulae discovery:

$P_i=201g|\frac{\mathrm{\λ}}{4\mathrm{\π}{G}_t{G}_r}\·\frac{E_i}{E_0}|\left(\mathrm{dB}\right)$

Wherein, λ is electric wave wavelength, G _tfor transmitter antenna gain (dBi), G _rfor receiving antenna gain, E _ithe electric field strength at test point i place in step (1) gained numerical map, E ₀for launching site place electric field strength.

5. ray tracing algorithm according to claim 1 carries out the method for Electromagnetic Simulation to different error maps, it is characterized in that: the calculating path loss value P described in step (4) _{ij ε}, by following formulae discovery:

$P_{\mathrm{ij\ϵ}}=201g|\frac{\mathrm{\λ}}{4\mathrm{\π}{G}_t{G}_r}\·\frac{E_{\mathrm{ij\ϵ}}}{E_0}|\left(\mathrm{dB}\right)$

Wherein, λ is electric wave wavelength, G _tfor transmitter antenna gain (dBi), G _rfor receiving antenna gain, E _{ij ε}the electric field strength to be side-play amount be test point i place in the jth class error maps of ε, E ₀for launching site place electric field strength.