WO2015010358A1

WO2015010358A1 - Geographical database construction method

Info

Publication number: WO2015010358A1
Application number: PCT/CN2013/083319
Authority: WO
Inventors: 张奇勋; 冯志勇; 金潇; 朱莹; 刘尚; 张轶凡; 张平
Original assignee: 北京邮电大学
Priority date: 2013-07-22
Filing date: 2013-09-11
Publication date: 2015-01-29
Also published as: CN103425749A; CN103425749B

Abstract

A geographical database construction method is provided. The method includes: on the basis of the sizes of geographical grids covered by authorized users, the largest theoretical power value of each grid is obtained through calculation; according to application limits of cognitive devices, the largest actually-usable power value used in each geographical grid is obtained and replaces the largest theoretical power value; the geographical grids same in largest actually-usable power value are integrated into a smallest number of rectangular areas, new geographic coordinates are constructed for the rectangular areas, and a geographical database is constructed by combining the largest actually-usable power values. The geographical database where the uneven size geographical grids small in data amount and small in calculation amount are stored is obtained with the present invention.

Description

A geodatabase construction method

Technical field

The present invention relates to the field of cognitive radio technologies, and in particular, to a method for constructing a geographic database. BACKGROUND OF THE INVENTION Cognitive radio technology can continuously adapt to changes in the external environment, and adjust its internal communication mechanism and parameter configuration to achieve adaptation to environmental changes, thereby improving system stability and improving utilization of spectrum resources. . An important principle of cognitive wireless networks while improving the utilization of spectrum resources is that access by unauthorized users cannot interfere with user communication in licensed frequency bands. The protection means for cognitive radios to authorized users mainly include geographic database.

The geodatabase stores the main information of the authorized users, and obtains the specific location of the available channels and the specific available power information by referring to the protection requirements of the authorized users, and stores them in the form of a geographical grid. However, there is no specific explanation for the geographical division method. It is generally considered that the size of the geographic grid is fixed and uniform.

The more the number of grids in the geodatabase, the smaller each grid. When the grid is too small, the database will need to store a lot of fine data, and it is very likely that some of the data is unnecessary. It is known that the amount of communication between devices becomes huge, resulting in an excessive amount of database storage and calculation. Summary of the invention

( ) Technical problem to be solved

The present invention provides a geodatabase construction method that reduces the number of rasters in a geodatabase. The present invention provides a geodatabase construction method, which comprises: - Sl, the geophysical size of the backbone authorized user to calculate the theoretical maximum power value of each grid;

52. Obtain a maximum available actual power value in each geographic grid according to a cognitive device application limit and replace the theoretical maximum power value;

53. Integrate the geographical grid with the same maximum power value into a minimum number of rectangular regions, establish new geographic coordinates for the rectangular region, and construct a geographic database according to the actual maximum ffl power value.

The cognitive device in step S2 should include: a maximum power upper limit value of the cognitive device, and a T limit Value and artificial limits on the maximum power value of cognitive devices.

The step S3 adopts a sub-optimal algorithm to integrate the geographical grids with the same actual maximum available power value into a minimum number of rectangular regions, including - scanning from left to right in order of the number of rows from small to large. A row of geographic rasters, when scanned into an unprocessed grid, marks this grid as the top left corner.

The line is scanned to the right from the grid labeled as the upper left corner until the maximum available power value is not equal or the last stop of the line has been reached, and the last grid with the same maximum power value is marked as the upper right corner.

In the order of the number of rows from small to large, scan the grid between the grid labeled as the upper left corner and the grid labeled as the upper right corner, until a row has a grid with the largest ffl power value unequal or There is still a grid with the largest available power value on the left or right side of the top left/upper right corner of the row. The leftmost grid of the last row that meets the condition is marked as the lower left corner, and the rightmost grid is marked as the right. The lower corner gets a rectangular area with 4 corners and marks all the grids in that area as processed.

The step S4 includes: establishing a new geographic coordinate according to the geographic coordinates of the upper left corner and the lower right corner of the rectangular area as a rectangular area, and combining the actual available maximum power value to obtain a new geographic cabinet, combining the original grid The grid is built into a geodatabase of non-uniformly sized geographic rasters.

(3) Beneficial effects

The present invention provides a method for constructing a geodatabase that replaces the actual available maximum power value within each geographic cell based on cognitive device application constraints and the theoretical maximum power value within each grid. Theoretical maximum power value; the geographic size of the actual available maximum power value is integrated into a minimum number of rectangular areas, and the actual grid can be compressed without the maximum power value of the grid. The rectangular area establishes new geographic coordinates and builds a geographic database in conjunction with the actual available maximum power value. After compression, the cognitive geodatabase is constructed with a non-uniform geographic grid, which reduces the number of geographic grids in the database, avoids the occurrence of too small grids, and at the same time, because it is based on the actual available maximum power value. The new geographic grid is integrated to avoid the problem that the grid is too large and the frequency utilization is not high, and the storage capacity and calculation amount of the database are reduced as much as possible. At the same time, the load on the database is reduced.

In the implementation of the present invention, the optimal algorithm is adopted, and the two corners of the left and right sides of the rectangular area are determined by scanning the grid with the same power value in a certain row, and then the columns in the left and right corners are scanned to the T, and the two left and right sides are determined. The corner determines the rectangular area and the label is processed. The method integrates the grid areas with the actual maximum available power values into the smallest number of rectangular areas with as little computational complexity as possible. It is guaranteed that the number of rectangular areas, that is, the new number of grids is the smallest. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart of an embodiment of the present invention;

2 is a diagram showing an example of a thumbnail image according to an embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be further described in detail below with reference to the drawings and specific embodiments.

The invention provides a geodatabase construction method. As shown in FIG. 1, the method includes:

51. Calculate the theoretical maximum power value of ffi in each grid based on the geographic grid size of the authorized user coverage;

53. Integrate the geographical grids with the same actual maximum power value into a minimum number of rectangular regions, establish new geographic coordinates for the rectangular regions, and construct a geographic database according to the actual maximum ffl power value.

The method replaces the theoretical maximum power value by the actual available maximum power value within each geographic frame based on cognitive device application constraints and the theoretical maximum power value used within each grid; the actual available maximum power value The same geographic grid is integrated into a minimum number of rectangular areas, and the grid that compresses the actual available maximum power value will not bring usable power loss; establish new geographic coordinates for the rectangular area, combined with the actual available maximum power value Build a geodatabase. After compression, the cognitive geodatabase is constructed with a non-uniform geographic grid. Since it is integrated into a new geographic grid based on the same geographical grid with the largest available maximum power value, the grid is too large and the frequency utilization is avoided. The problem of low rate is the same as reducing the number of geographical grids in the database, avoiding the occurrence of too small grids, reducing the storage and calculation of the database as much as possible, and reducing the load on the database.

In an embodiment of the present invention, the cognitive device application restrictions in step S2 include: an available maximum power upper limit value, a lower limit value of the cognitive device, and an artificial limit on the maximum power value of the cognitive device.

At present, the calculation of the channel power can be considered to ensure the normal operation of the authorized user receiver. Since the propagation environment of each grid is different from that of the authorized user receiver, the calculated available power value generally varies with the geographical location. different. However, in actual work, the power value available to cognitive devices is also affected by other factors, such as: 1. The regulatory authority may limit the power of the device in certain border areas to avoid interference to other areas; Fixed or mobile cognitive devices have a certain power cap due to their respective device types; 3, considering the actual 3⁄4 nature, fixed devices are not sensitive to very low power, so there is a certain power lower limit.

In step S3 of the embodiment of the present invention, the geographic grid with the same actual maximum power value is integrated into a minimum number of rectangular regions by using a sub-optimal algorithm, including - In the order of the number of rows from small to large, A scans a row of geo-grid from left to right, and marks the raster as the upper-left corner when scanning to an unprocessed raster.

The grid labeled as the upper left corner scans the line to the right until the maximum available power value is not equal or the last stop of the line is reached, and the last maximum maximum power value is marked as the upper right corner.

In the order of the number of rows from small to large, scan the column geographical grid between the top left corner and the grid labeled upper right corner until a row has a grid with the largest ffi power value unequal. Or the left or right corner of the grid in the upper left/upper right corner of a row has a grid with the largest available power value equal, marking the leftmost grid of the last row that meets the condition as the left T corner, and the rightmost grid is marked as Right T corner, get a rectangular area with 4 corners, and mark all the grids in the area as processed.

The optimal algorithm is used to find the two corners of the left and right sides of the rectangular area by scanning the grid with the same power value in a row, and then scanning the columns of the left and right corners downward to determine the two corners below and below to determine the rectangular area. And marked the processing. The method integrates the grid areas with the same maximum available power value into the smallest number of rectangular areas with as little computational complexity as possible. It is guaranteed that the number of rectangular areas, that is, the new number of grids is the smallest.

In another embodiment of the present invention, the step S4 includes: establishing a new geographic coordinate according to the geographic coordinates of the upper left corner and the lower right corner of the rectangular area as a rectangular area, and combining the actual maximum power value to obtain a new one. A geographic grid, combined with the original polar grid, is built into a geodatabase of non-uniformly large geographic rasters.

In the image shown in FIG. 2, an embodiment will be specifically described to explain a specific step method.

The theoretical maximum power value used in each grid is calculated based on the geographic grid size covered by the authorized user: As shown in (a) of the figure, the value in each cabinet represents the theoretical maximum power that can be used. value.

Calculate the theoretical maximum power value used in each pole according to the typical grid size covered by the original authorized households without disturbing the authorized users. The maximum power value is the maximum transmit power value that the cognitive device can use in the available channels of the unlicensed user in a certain geographical location, so it must be based on the principle of not disturbing the authorized user.

The theoretical maximum power values calculated in the existing methods include:

The authorized user evaluates the quality of the received signal by the location probability. The location probability is defined as the probability that the television receiver can work normally at a certain location. The location probability is related to the received authorized user signal strength and the received interference signal strength.

The emergence of cognitive device interference will inevitably reduce the probability of authorizing users' locations. The maximum amount of location probabilities allowed to decrease is defined based on the sensitivity of the authorized user's receiver or the quality of the coverage of the regulatory component.

Based on the maximum amount of location probabilities allowed to be reduced and the loss between the cognitive device and the authorized user receiver, the theoretical maximum power value that the cognitive device can make can be calculated. Step B: According to the cognitive device application limitation, obtain the actual maximum power value available in each geographic grid and replace the theoretical maximum power value; as shown in the figure, replace the maximum power value used by some of the grids with 20. If the actual available maximum power value of the cognitive device is 20, replace the power value in the cabinet with a theoretical power value greater than 20 with 20, that is, the power value is "truncated".

Step C: Integrate the geographical grid with the same actual maximum power value into a minimum number of rectangular regions, establish new geographic coordinates for the rectangular region, and construct a geographic database according to the actual available maximum power value.

Wherein the integration into a minimum number of rectangular regions includes:

Scans a row of geographic rasters from left to right in order of the number of rows from small to large, and marks the raster as the upper left corner when scanning to an unprocessed raster.

^The grid labeled as the upper left corner scans the line to the right until the maximum available power value is not equal or has stopped at the end of the line, marking the last maximum 可3⁄4 power value equal to the upper right angle.

In the order of the number of rows from small to large, scan the grid between the grid labeled as the upper left corner and the grid labeled as the upper right corner, until a row has a grid with a maximum available power value that is not equal. There is still a grid with the largest available power value on the left or right side of the top left/upper right corner of the row. The leftmost grid of the last row that meets the condition is marked as the lower left corner, and the rightmost grid is marked as the lower right corner. , get a rectangular area with 4 corners, and mark all the grids in the area as processed. In (c) (d) (e) of Figure 2, three geographically rectangular areas with the same maximum available power are found. The integration method is described below in conjunction with Figure 2 (c).

The overall scan order is the first row and the first column, the first row and the second column...the first row and the tenth column, the second row and the first column...the tenth row and the tenth column, each time you scan to a grid, you need to confirm There are no grids of equal power on the right and below.

(1) Starting from the first line, the first is the grid with a power value of 7, the 7» grid is marked as the upper left corner of the rectangular area, and scanned to the right. Since the right side is 8 not equal to 7, the 7 grid is marked. Is the upper right corner of the rectangular area, and then scans the column downwards. The grid labeled as the upper left corner and the grid labeled as the upper right corner are the same grid, so only the column where the 7 grid is located is drawn downward (ie, One column), when scanning down to the second row, it is found that the first row of the second row is not equal to 7, and then based on the end of the scan of the grid 7, the 7 grid is also marked as the lower left corner and the lower right corner of the rectangular area. In other words, the final 7 grid has not changed. Mark the first column of the first row and delete it as "processed" after scanning;

Scan the first row and the second column, that is, the grid 8, which is completely the same as the grid 7, and the subsequent steps 9, 8, 7, 12, and 15 are also the same steps;

(3) Scan to the 20th column of the first row, mark the grid as the upper left corner of the rectangular area, scan to the right, and find that the power value is the same, until the end of the line, the grid of the first row and the 10th column 20 is marked as the upper right corner of the rectangular area, and then the column scan is performed. The grid of the same power includes the 8th, 9th, and 10th columns, so the three columns of each row are scanned downward, and the second row is 8, 9, and 10 columns. The grid is still 20, so continue to scan down, the third row 8, 9, 10 columns of three grids still continue to sweep down 20 The fourth row, 8, 9, and 10 columns are not all 20, so the end of the scan, the third row and the eighth column of the grid are marked as the lower left corner of the rectangular area, the third row of the 10th column of the grid mark Is the lower right corner of the rectangular area. At this point, all four corners of the rectangular area are found, and all the original rasters of this rectangular area are marked as "processed".

This ^, all the grids in the first line have been processed, the second line is scanned, and the first column is processed from left to right. The steps are the same as the first line. It is worth noting that the second line and the seventh column are scanned. After 14th, since the second row 8-10 of the right row has been processed, the second row has all been processed, and then the third row is scanned. The overall process is analogized until all rows are scanned. It ensures that the grid will not be scanned repeatedly, and the calculation complexity is low.

A new geographic coordinate is created for the rectangular region, and a geographic database is constructed in conjunction with the actual available maximum power value. A new geographic coordinate may be established for the rectangular area according to the geographic coordinates of the upper left corner and the lower right corner of the rectangular area, and a new geographic grid may be obtained according to the actual available maximum power value, and the non-uniform size geography is constructed in combination with the original grid. Extremely geographical database. As shown in (d) of the figure.

In summary, the present invention constructs a geodatabase through a non-homogeneous grid, and improves the problem of large amount of database storage calculation caused by a small cabinet size in a geodatabase with uniform grid size, and ensures the efficient use of the spectrum. The amount of data stored in the geodatabase is greatly reduced, and the load on the database is reduced.

The above is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can make thousands of improvements and replacements without departing from the technical principles of the present invention. Substitutions are also considered to be the scope of protection of the present invention.

Claims

claims

1. A geodatabase construction method, characterized in that the method includes:

S Calculate the theoretical maximum power value used in each cabinet based on the size of the geographical grid covered by the authorized user; S2. According to the cognitive device application restrictions, obtain the actual maximum power value available in each geographical grid and replace the theoretical maximum power value;

S3. Integrate the geographical grids with the same actual available maximum power value into a minimum number of rectangular areas, establish new geographical coordinates for the rectangular area, and construct a geographical database based on the actual available maximum power value.

2. The method according to claim 1, characterized in that, the cognitive device application restrictions in step S2 include: an upper limit value, a lower limit value of the available maximum power of the cognitive device, and artificial restrictions on the maximum power value of the cognitive device. limit.

3. The method according to claim 1, characterized in that, in step S3, a sub-optimal algorithm is used to integrate the geographical grids with the same actual available maximum power value into a minimum number of rectangular areas, including - from small to small In the order of the largest row number, trace a certain row of geographic grids from left to right. When an unprocessed grid is scanned, mark this grid as the upper left corner;

Scan the row right from the grid marked as the upper left corner until the maximum available power value is unequal or the row reaches the final stop, and the last grid with the same maximum available power value is marked as the upper right corner;

In order of row number from small to large, scan the column geographical raster between the raster marked as the upper left corner and the raster marked as the upper right corner until there is a raster with unequal maximum possible power values in a row or a certain raster. If there is a grid with the same maximum available power value to the left or right of the upper left corner/upper right corner of the row, mark the leftmost grid of the last row that meets the conditions as the lower left corner, and the rightmost grid as the lower right corner. , obtain a rectangular area with 4 corners, and mark all rasters in this area as processed.

4. The method of claim 1, wherein step S4 includes:

Establish new geographical coordinates for the rectangular area according to the geographical coordinates of the upper left corner and lower right corner of the rectangular area, combine it with the actual available maximum power value to obtain a new geographical grid, and combine it with the original grid to construct a non-uniform size geographical grid. Grid geodatabase.