CN108111972A - Indoor WiFi Site Surveys method based on signal strength and space division - Google Patents

Abstract

The invention discloses an indoor WiFi access point positioning method based on signal strength and space division, comprising the following steps: step 1: sensing WiFi signals, and determining the SSID of a target AP to be positioned; step 2: determining the room where the target AP is located; Step 3: Set the expected threshold of room positioning accuracy as d; Step 4: Divide the area where the target AP is located into four areas; Step 5: Determine the reference point by dichotomy, and collect data on the reference point; Step 6: Pass Compare the signal strength values to determine the area where the maximum relative signal strength is located; Step 7: Determine the next positioning area of the target AP; Step 8: Determine whether the area where the target AP is located reaches the expected threshold d of the positioning accuracy of the set room; Step 9: Output the coordinates of the center point of the area that reaches the expected threshold of positioning accuracy of the set room. The present invention significantly improves the positioning accuracy of indoor WiFi access points.

Description

Indoor WiFi access point positioning method based on signal strength and space division

technical field

The invention relates to the technical field of wireless positioning, in particular to an indoor WiFi access point positioning method based on signal strength and space division.

Background technique

In recent years, with the rapid development of wireless networks, the use of WiFi access points (Access Point, AP) has become more and more extensive, such as supermarkets, hotels, cafes, schools and other areas have WiFi access points. The popularization of WiFi brings aspects to people's life and study, and at the same time, it also makes it possible for illegal and illegal WiFi access points to exist in some special places and departments. The indoor WiFi access point positioning technology can not only find illegal and illegal WiFi, but also locate its location. Therefore, the development of indoor WiFi access point positioning technology has very important research value for discovering and locating illegal and illegal WiFi, and it is also of great significance for doing a good job of security and confidentiality inspection. At present, there are two typical methods for indoor WiFi positioning: one is a positioning algorithm based on RSS ranging (Received Signal Strength, referred to as RSS, that is, received signal strength); the other is based on location fingerprint positioning algorithm; based on RSS ranging There are two ways to calculate the distance in the positioning algorithm: one is to calculate the distance through the signal propagation time, and the other is to calculate the distance through the path loss model; and then through positioning methods such as trilateration, hyperbolic method and least squares Multiplication, to obtain the location information of the target AP; to calculate the distance through the signal propagation time, a high-precision time measuring instrument is required, which makes the cost higher; and the distance obtained by using the path loss model has a large error compared with the actual distance, so The indoor positioning accuracy of this method is not high; the other is based on the location fingerprint positioning algorithm, which includes two stages: offline and online; the offline stage is mainly to collect RSS sample data and establish a location fingerprint database; in the online stage, real-time positioning, the user will The measured RSS value at the current location is matched with the data collected in the offline phase, and the reference point closest to the wireless signal characteristics of the current location is found to obtain the location information of the target AP. In order to solve the above problems, the present invention provides an indoor WiFi access point positioning method based on signal strength and space division.

Contents of the invention

Aiming at the deficiencies and defects of the prior art, the present invention provides an indoor WiFi access point positioning method based on signal strength and space division. The method is based on the idea of successive approximation, and performs a small number of divisions on the area where the target WiFi access point is located. And use a small number of reference points to determine the location of the target WIFI access point by comparing the collected signal strength multiple times, and greatly improve the indoor positioning accuracy.

In order to achieve the stated purpose, the technical solution adopted in the present invention is: a method for positioning indoor WiFi access points based on signal strength and space division, comprising the following steps:

Step 1: Perceive the WiFi signal and determine the SSID of the target AP to be located;

Step 2: Determine the room where the target AP is located;

Step 3: Set the expected threshold of room positioning accuracy as d;

Step 4: Divide the area where the target AP is located into 4 areas;

Step 5: Determine the reference point by dichotomy, and collect data at the reference point;

Step 6: By comparing the signal strength values, determine the area where the maximum value of the relative signal strength relationship is located;

Step 7: Determine the next positioning area of the target AP;

Step 8: Determine whether the area where the target AP is located reaches the expected threshold d of the positioning accuracy of the set room;

Step 9: Output the coordinates of the center point of the area that reaches the expected threshold of positioning accuracy of the set room.

Further, the step 1 specifically includes: using a wireless network scanning tool on the mobile phone to obtain a signal list of WiFi around the locator, and according to the scanned signal list information, determine the SSID of the target AP to be located.

Further, said step 2 specifically includes:

The locator patrols the room where the target AP may exist, and according to the change of the received signal strength RSS, the room with the largest RSS value is determined as the room where the target AP is located.

Further, said step 4 specifically includes:

Take the center point of the area where the target AP is located as the origin, divide the area into 4 areas with horizontal and vertical dividing lines, and name the 4 equally divided areas in the order of the first quadrant to the fourth quadrant for and area; where i represents the number of divisions, j represents the quadrant where it is located, Indicates the area where the jth quadrant is divided for the ith time;

The area where the target AP is located is expressed as H _i , and i represents the number of divisions. When i=1, that is, H ₁ indicates that the first divided area is the room where the target AP is located. The length of the room is the y-axis, and the width is the x-axis. Create a two-dimensional coordinate system.

Further, said step 5 specifically includes:

Use the dichotomy method to determine 3 reference points on the horizontal dividing line, and use the mobile phone's wireless network scanning tool and directional antenna on different reference points to measure the RSS and direction from the reference point to the target AP.

Further, said step 6 specifically includes:

By comparing the signal strength values of the target AP measured at different reference points, the relative relationship value of signal strength is obtained, and the area where the maximum value of the relative relationship of signal strength is determined; RSS value to get a large RSS value.

Further, said step 7 specifically includes:

If the maximum value of the relative relationship of signal strength is at the position of the center point, then determine one or more reference points by dichotomy on the vertical dividing line in the direction pointed to by the maximum value, and compare the values measured on the vertical dividing line reference point Obtain the signal strength value of the target AP, obtain the relative relationship value of the signal strength, and determine that the area where the maximum value of the relative signal strength relationship is located is the location area H _i+1 of the next target AP;

If the maximum value of the relative signal strength relationship is not at the central point, the area where the maximum value of the relative signal strength relationship obtained in step 6 is located is determined as the location area H _i+1 of the next target AP.

Further, said step 8 specifically includes:

In the positioning area H _i+1 of the target AP, determine whether the area where the target AP is located reaches the expected positioning accuracy threshold of the set room, that is, determine whether (d _x <d) && (d _y <d) holds true. Among them, d _x represents the maximum distance that can be moved on the x-axis with the center point of each divided area as the origin, and d _y represents the maximum distance that can be moved on the y-axis with the center point of each divided area as the origin.

The beneficial effects of the present invention are:

1. The present invention is based on the indoor WiFi access point positioning method of signal strength and space division, at first determine the center point of the area where the target WiFi access point is located, and take the center point as the origin, divide it with horizontal dividing line and vertical dividing line Divide into 4 areas, determine the reference point on the horizontal or vertical dividing line on the area dividing line by dichotomy; divide the area where the target WIFI access point is located a few times and use a small number of reference points, through Compare the collected RSS values multiple times to determine the final location of the target AP. Improve the positioning efficiency of indoor WIFI access points.

2. The present invention is based on the indoor WiFi access point positioning method of signal strength and space division. By comparing the signal strength values measured at each reference point, the area corresponding to the reference point with the largest signal strength value is used as the divided target WIFI The area where the access point is located; the indoor WiFi access point positioning method based on signal strength and space division is not affected by the structure of the room, the type of WiFi source and the number of APs, and improves the positioning accuracy of the indoor WiFi access point.

Description of drawings

FIG. 1 is a flowchart of the indoor WiFi access point positioning method based on signal strength and space division in the present invention.

FIG. 2 is a schematic diagram of the first space division of the indoor WiFi access point positioning method based on signal strength and space division according to the present invention.

FIG. 3 is a schematic diagram of the second space division of the indoor WiFi access point positioning method based on signal strength and space division according to the present invention.

FIG. 4 is a schematic diagram of the third space division of the indoor WiFi access point positioning method based on signal strength and space division according to the present invention.

FIG. 5 is a schematic structural diagram of room A in an embodiment of the method for locating an indoor WiFi access point based on signal strength and space division in the present invention.

FIG. 6 is a schematic structural diagram of room B in an embodiment of the indoor WiFi access point positioning method based on signal strength and space division of the present invention.

FIG. 7 is a schematic structural diagram of room C in an embodiment of the indoor WiFi access point positioning method based on signal strength and space division of the present invention.

Fig. 8 is a schematic diagram of the positioning error comparison between the method and the positioning algorithm based on RSS ranging in different room structures of an embodiment of the indoor WiFi access point positioning method based on signal strength and space division of the present invention.

Fig. 9 is a schematic diagram of the positioning error comparison between the method and the positioning algorithm based on RSS ranging for different types of transmission sources of the embodiment of the indoor WiFi access point positioning method based on signal strength and space division of the present invention.

FIG. 10 is a schematic diagram of the comparison of the number of APs with the positioning error between this method and the positioning algorithm based on RSS ranging in an embodiment of the indoor WiFi access point positioning method based on signal strength and space division of the present invention.

11 is a schematic diagram of the positioning process when the target AP in room B is at position 2 in the embodiment of the indoor WiFi access point positioning method based on signal strength and space division of the present invention.

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment the present invention is described in further detail:

Embodiment 1: As shown in Figure 1, a method for positioning an indoor WiFi access point based on signal strength and space division includes the following steps:

Step 1: Perceive the WiFi signal and determine the SSID of the target AP to be located;

Step 2: Determine the room where the target AP is located;

Step 3: Set the expected threshold of room positioning accuracy as d;

Step 4: Divide the area where the target AP is located into 4 areas;

Step 5: Determine the reference point by dichotomy, and collect data at the reference point;

Step 6: By comparing the signal strength values, determine the area where the maximum value of the relative signal strength relationship is located;

Step 7: Determine the next positioning area of the target AP;

Step 8: Determine whether the area where the target AP is located reaches the expected threshold d of the positioning accuracy of the set room;

Step 9: Output the coordinates of the center point of the area that reaches the expected threshold of positioning accuracy of the set room.

Embodiment 2, an indoor WiFi access point positioning method based on signal strength and space division, comprising the following steps:

Step 1: Perceive the WiFi signal and determine the SSID of the target AP to be located; use the wireless network scanning tool on the mobile phone to obtain the signal list of the WiFi around the locator, and determine the SSID of the target AP to be located according to the scanned signal list information.

Step 2: Determine the room where the target AP is located; the locator patrols the room where the target AP may exist, and determines the room with the largest RSS value as the room where the target AP is located according to the change of the received signal strength RSS.

Step 3: Set the expected threshold of room positioning accuracy as d; the setting of the positioning accuracy threshold d will affect the number of divisions of the algorithm and the amount of collected data. If d is set smaller, the number of divisions and the number of collected data will be corresponding The increase of , resulting in a relatively long positioning time; otherwise, the number of divisions and the number of collected signal strengths will decrease accordingly, which will affect the positioning accuracy. The expected threshold of positioning accuracy is set to 0.5m<d<1m.

Step 4: Divide the area where the target AP is located into 4 areas;

Take the center point of the area where the target AP is located as the origin, divide the area into 4 areas with horizontal and vertical dividing lines, and name the 4 equally divided areas in the order of the first quadrant to the fourth quadrant for and area; where i represents the number of divisions, j represents the quadrant where it is located, Indicates the area where the jth quadrant is divided for the ith time;

The area where the target AP is located is expressed as H _i , and i represents the number of divisions. When i=1, that is, H ₁ , that is, H ₁ indicates that the first divided area is the room where the target AP is located. The length of the room is the y-axis, and the width is For the x-axis, establish a two-dimensional coordinate system.

Step 5: Determine the reference point by the dichotomy method and collect data on the reference point; determine three reference points by the dichotomy method on the horizontal dividing line, use the wireless network scanning tool of the mobile phone and the directional antenna on different reference points, and measure the reference points separately Point to the RSS and direction of the target AP.

Step 6: By comparing the signal strength values, determine the area where the maximum value of the relative signal strength relationship is located; by comparing the signal strength values of the target AP measured at different reference points, obtain the relative signal strength value, and determine the area where the maximum value of the relative signal strength relationship is located ; The relative signal strength value refers to a large RSS value obtained by comparing RSS values in different directions at the same reference point.

Step 7: Determine the next positioning area of the target AP;

If the maximum value of the relative relationship of signal strength is at the position of the center point, then determine one or more reference points by dichotomy on the vertical dividing line in the direction pointed to by the maximum value, and compare the values measured on the vertical dividing line reference point Obtain the signal strength value of the target AP, obtain the relative relationship value of the signal strength, and determine that the area where the maximum value of the relative signal strength relationship is located is the location area H _i+1 of the next target AP;

If the maximum value of the relative signal strength relationship is not at the central point, the area where the maximum value of the relative signal strength relationship obtained in step 6 is located is determined as the location area H _i+1 of the next target AP.

Step 8: Determine whether the area where the target AP is located reaches the expected threshold d of the positioning accuracy of the set room; in the positioning area H _i+1 of the target AP, determine whether the area where the target AP is located reaches the expected threshold of positioning accuracy of the set room, that is (d Whether _x <d)&&(d _y <d) is true; among them, d _x represents the maximum distance that can be moved on the x-axis with the center point of each divided area as the origin, and d _y represents the center point of each divided area as the origin The maximum distance that can be moved on the y-axis.

Step 9: Output the coordinates of the center point of the area that reaches the expected threshold of positioning accuracy of the set room.

In this embodiment, 3 reference points are selected for the area where the target WIFI access point is located, as shown in Figure 2, Figure 3, and Figure 4, which respectively represent the results of the first division, the results of the second division and the results of the third division , the arrow indicates the direction of collecting signal strength; the area where the target AP is located, the area can be expressed as H _i , i indicates the number of divisions, when i=1, H ₁ indicates that the first divided area is the entire room, and the length of the room is The y-axis, the width is the x-axis, establish a two-dimensional coordinate system, as shown in Figure 2, use the horizontal dividing line and the vertical dividing line to divide the area into 4 areas, named according to the order of the first quadrant to the fourth quadrant for and Area; A _i , B _i and C _i (i=1, 2, 3) represent selected reference points, A _i represents the center point of the area, and its coordinates can be expressed as (width _i , length _i ).

In Figure 2, the coordinates of _A1 are (width ₁ , length ₁ ), where width ₁ is half of width, and length ₁ is half of length; the data of each reference point collected is a triplet (a, b, c) represents, where a represents the position of the reference point, b represents the RSS of the target AP measured in the area above the reference point a, and c represents the RSS of the target AP measured in the area below the reference point a; for example, the data at point A _i is represented by three A tuple is represented as where A _i represents the position of the reference point, Indicates the RSS value of the target AP measured in the area above the A _i reference point, Indicates that the RSS value of the target AP is measured in the area below the A _i reference point; because each reference point needs to measure the RSS of two areas, by comparing the measured signal strength values of the two areas, the signal at the A _i point is obtained Intensity Relative Value Empathy and Finally, the maximum value of the signal strength relative relationship can be determined The area where it is located is the next positioning area, and the area where the signal strength relative relationship is maximum is discussed, there are the following three situations:

(1) If the RSS _max is in B _i or C _i , the area where the RSS _max is located is the next positioning area;

(2) If RSS _max is in A _i , and the maximum value is Then it is necessary to determine the reference point D _i by dichotomy on the vertical dividing line above A _i (otherwise a reference point is determined by dichotomy on the vertical dividing line below A _i ), in the left direction and right direction of the reference point Measure the RSS to the target AP in the side direction, and compare the measured RSS values in Indicates the area on the right side of D _i , Indicates the area on the left side of D _i , The area where it is located is the next positioning area;

(3) If in the above two cases, the next positioning area cannot be determined, take D _i (or a reference point determined by dichotomy on the vertical dividing line below A _i ) as the center point, and on both sides of it Determine two reference points by dichotomy, collect data at the reference points, and compare the collected RSS values to determine the area where the RSS _max is located as the next positioning area.

In the i-th division, the coordinate formula of the center point is as follows:

Aiming at an indoor WiFi access point positioning method based on signal strength and space division disclosed in the present invention, in order to verify the effectiveness and feasibility of this method, the method is verified by conducting positioning experiments in an actual environment, and the room is specifically analyzed. The impact of structure, source type and number of APs on the accuracy of the positioning method.

The environment selected for the positioning experiment is 6 rooms with a total size of 50m×22m. In the experiment, 5 AP locations were randomly selected in 3 rooms with different structures, and 4 different types of WiFi access points were set up in each location, including fixed APs ( Router) and portable AP (mobile phone), a total of 60 groups of experiments were carried out; the positioning equipment used in the experiment mainly consists of a directional antenna and a mobile phone, and the mobile phone is used to display the scanned wireless signal. In the positioning algorithm based on the relative relationship between signal strength and space division, the direction angle is determined using a directional antenna. The main purpose of using a directional antenna is to enhance signal strength and increase anti-jamming capability.

Through the AP information (such as AP SSID, MAC, RSS, etc.) obtained by scanning the equipment in the corridor, determine the SSID of the located AP and the number of APs. After determining the SSID of the located AP, use the device to measure its signal strength value to determine its location. Room. The present invention has carried out experiments on the factors affecting the positioning results, including different room structures, different types of WiFi transmission sources and the number of APs, and the results are as follows.

1) Different room structures; use 3 different room structures (including the environment and room size) for experiments; the settings in the 3 rooms are shown in Figure 5, Figure 6 and Figure 7, and the size of room A is 20m× 10m, there are multiple computers, tables, chairs, cabinets and other items placed in the room, the materials of the tables and cabinets are iron; the size of room B is 17m×10m, there are iron vertical filing cabinets and Wooden tables, small cabinets, etc.; the size of room C is 13m×10m, and iron bookshelves, tables and chairs are placed in the room.

Under the condition that the expected threshold d of room positioning accuracy is set to 1 meter, the experimental results shown in Figure 8 show that the size of the room will slightly affect the positioning accuracy. 0.3 meters. Therefore, the environment in the room will not affect the positioning result.

In order to compare the positioning accuracy of the algorithm proposed by the present invention and the ranging algorithm based on RSS, the algorithm proposed by the present invention and the ranging algorithm based on RSS are used for positioning in the environments shown in rooms A, B and C respectively. The positioning algorithm based on RSS ranging uses the path loss model to convert the RSS value of the target AP measured at the reference point into the distance from the reference point to the target AP, and then uses the standard least square method for positioning. The influence of different room structures on the positioning accuracy is analyzed by using the positioning algorithm based on RSS ranging and the positioning algorithm proposed by the present invention, and the experimental results are shown in FIG. 8 . In Fig. 8, wherein the abscissa represents the 5 AP positions arbitrarily selected in Figs. Error, the solid line represents the error produced by the positioning algorithm based on RSS ranging; As can be seen from the figure, the accuracy of the positioning algorithm proposed by the present invention is obviously higher than the positioning accuracy of the positioning algorithm based on RSS ranging.

2) Different types of WiFi transmission sources; choose 2 different types of fixed and 2 different types of portable transmission sources; the fixed and portable models are shown in Table 1.

Table 1

source type Stationary 1 Stationary 2 Portable 1 Portable 2 model TL-WDR6500 TL-WR842N MI4LTE Nexus5

Using different types of transmitters in Table 1, experiments were carried out on five target AP locations in three rooms A, B, and C respectively; since the algorithm process is the same, taking one location in one room as an example, the experimental process to describe. As shown in Figure 11, it describes the specific process of the algorithm when the target AP in room B is at position 2. The vertical black arrow in the figure indicates the direction of measuring signal strength, and the area pointed by the white arrow is the enlarged view of the arrow tail area.

When the target AP in room B is at position 2 using different types of transmitting sources in Table 1, the data collected at each reference point in Figure 11 is represented by a triplet, as shown in Table 2.

Table 2

From the data in Table 2, it can be seen that at the same location, different types of transmitters will affect the RSS value. The RSS measured by fixed transmitters is quite different from the RSS measured by portable transmitters. The RSS measured by the transmitting source (portable transmitting source) is not much different. Although different types of emission sources will affect the RSS value, they will not affect the positioning accuracy of the algorithm proposed by the present invention.

(a) Experiments were carried out using 4 different types of transmitters, and the measurement times, actual coordinates, output coordinates and positioning errors of 5 target APs in room A were calculated. The results are shown in Table 3.

table 3

Location of AP in Room A position 1 position 2 position 3 position 4 position 5 Measurement times 15 15 15 15 16 Actual coordinates of AP (9.22,18.44) (4.85,15.78) (5.94,14.07) (2.03,10.63) (5.15,0.83) Output the coordinates of the AP (9.06,18.13) (4.69,15.62) (5.94,14.38) (2.19,10.63) (5.31,0.63) Positioning error (m) 0.35 0.22 0.31 0.16 0.26

From the data in Table 3, it can be obtained that the highest positioning error in room A is 0.35 meters, the lowest positioning error is 0.16 meters, and the average positioning error is 0.26 meters.

(b) Calculate the measurement times, actual coordinates, output coordinates and positioning errors of the five target APs in room B, and the results are shown in Table 4.

Table 4

Location of AP in room B position 1 position 2 position 3 position 4 position 5 Measurement times 12 12 12 13 12 Actual coordinates of AP (7.97,16.74) (0.16,15.16) (4.85,10.09) (6.46,6.04) (9.69,0.26) Output the coordinates of the AP (7.81,16.47) (0.31,15.41) (4.69,10.09) (6.56,5.84) (9.69,0.53) Positioning error (m) 0.31 0.29 0.16 0.22 0.27

From the data in Table 4, it can be obtained that the highest positioning error in room B is 0.31 meters, the lowest positioning error is 0.16 meters, and the average positioning error is 0.25 meters.

(c) Calculate the measurement times, actual coordinates, output coordinates and positioning errors of the five target APs in room C, and the results are shown in Table 5.

table 5

Location of AP in room B position 1 position 2 position 3 position 4 position 5 Measurement times 9 9 9 9 9 Actual coordinates of AP (7.56,12.08) (0.32,10.16) (3.75,6.50) (8.44,4.06) (2.03,1.02) Output the coordinates of the AP (7.81,11.78) (0.63,10.16) (3.44,6.09) (8.44,4.47) (2.19,1.22) Positioning error (m) 0.39 0.31 0.15 0.41 0.26

From the data in Table 5, it can be obtained that the highest positioning error in room C is 0.51 meters, the lowest positioning error is 0.26 meters, and the average positioning error is 0.38 meters.

In the environment shown in the three rooms A, B and C, because the environmental factors in A and B rooms are more complex and will affect the positioning accuracy of different types of emission sources, the experiment chooses room C with a relatively empty indoor environment. Using the positioning algorithm based on RSS ranging and the positioning algorithm proposed by the present invention to analyze the influence of different types of emission sources on the positioning accuracy, the experimental results are shown in Figure 9. In FIG. 9 , the abscissa represents the positions of five APs arbitrarily selected in room C, and the ordinate represents the corresponding positioning errors at the five selected AP positions. The solid line in the figure represents the positioning error generated by the algorithm based on RSS ranging. The dashed line represents the localization error produced by the proposed algorithm. It can be seen from the figure that different types of emission sources will affect the positioning accuracy based on the RSS ranging algorithm, but will not affect the positioning accuracy of the algorithm proposed by the present invention.

(3) The number of APs; the present invention can locate the position of the AP when there is only one AP in the room, and can also locate the position of one of the target APs from multiple APs in the room; when there is only one AP in the room, measure at the reference point When the RSS of the AP is measured, the range of change is small, making the measured RSS value relatively stable; when there are multiple APs in the room, when the RSS of the target AP is measured at the reference point, the range of change is relatively large, making the RSS value relatively stable. The measured RSS value is unstable. The experiment was carried out in room C, where the indoor environment is relatively empty, and the experimental results are shown in Tables 6-8; Tables 6-8 are the data measured when the distance from the target AP is 1 meter, 3 meters, and 5 meters, respectively.

Table 6 Measured data when the distance from the target AP is 1 meter

Number of APs (units) 1 2 3 4 RSS(dBm)(with directional antenna) -25 -28 -28 -26 Amplitude range of RSS (with directional antenna) -24～-28 -27～-30 -24～-30 -24～-30 RSS(dBm) (without directional antenna) -35 -37 -36 -37 Amplitude range of RSS (without directional antenna) -30～-36 -35～-40 -32～-40 -37～-43

Table 7 Measured data when the distance from the target AP is 3 meters

Number of APs (units) 1 2 3 4 RSS(dBm)(with directional antenna) -36 -37 -39 -39 Amplitude range of RSS (with directional antenna) -34～-39 -35～-40 -37～-44 -37～-46 RSS(dBm) (without directional antenna) -42 -41 -40 -41 Amplitude range of RSS (without directional antenna) -38～-44 -41～-47 -39～-46 -40～-48

Table 8 Measured data when the distance from the target AP is 5 meters

Number of APs (units) 1 2 3 4 RSS(dBm)(with directional antenna) -42 -44 -42 -41 Amplitude range of RSS (with directional antenna) -40～-45 -40～-47 -38～-47 -37～-45 RSS(dBm) (without directional antenna) -50 -54 -48 -48 Amplitude range of RSS (without directional antenna) -48～-52 -49～-55 -45～-55 -39～-53

From Tables 6 to 8, it can be seen that the number of APs will slightly affect the range of the measured RSS value and its amplitude. Use the positioning algorithm based on RSS ranging and the positioning algorithm proposed by the present invention to analyze the impact of the number of APs on positioning. The impact of accuracy, the experimental results are shown in Figure 10.

Among them, the abscissa represents the 5 AP positions randomly selected in room C, and the ordinate represents the corresponding positioning error at the 5 selected AP positions. When the AP is 1, it means that there is only one target AP in the room and no other APs. Exist; when the AP is not 1, it means that there are other APs in the room. The solid line in the figure represents the positioning error generated by the positioning algorithm based on RSS ranging, and the dotted line represents the positioning error generated by the positioning algorithm proposed by the present invention. It can be seen from the figure that the number of APs will slightly affect the positioning accuracy of the positioning algorithm based on RSS ranging, but will not affect the positioning accuracy of the algorithm proposed by the present invention.

In summary, the indoor WiFi access point positioning method based on signal strength and space division proposed by the present invention does not affect the positioning accuracy of the method for different room structures, different types of WiFi transmission sources and the number of APs. Therefore, the positioning method proposed by the present invention has strong stability and high precision.

An indoor WiFi access point positioning method based on signal strength and space division proposed by the present invention is used for indoor WiFi access point positioning; the method measures the RSS and direction from different reference points to the target WiFi access point by using equipment , by comparing the measured RSS values, the next positioning area is determined as the area where the signal strength maximum is located, until the current target area is reduced to the set accuracy threshold, and the location coordinates of the target WiFi access point are obtained; the experimental results show that , the average positioning error of this method is 0.3 meters, and the minimum positioning error reaches 0.16 meters. The positioning accuracy of the algorithm proposed by the present invention is high. This invention can provide technical support for users or network administrators, so that they can find the target more quickly and accurately The location of the WiFi access point.

It should be noted that the above-mentioned embodiments are only used to illustrate or explain the principle of the present invention, and are not intended to limit the present invention. Therefore, some improvements can be made without departing from the spirit and scope of the present invention. and modifications, these improvements and modifications should be considered within the patent scope of the present invention.

Claims (8)

1. a kind of indoor WiFi access point positioning method based on signal strength and space division, it is characterized in that, comprises the following steps: Step 1: Perceive the WiFi signal and determine the SSID of the target AP to be located; Step 2: Determine the room where the target AP is located; Step 3: Set the expected threshold of room positioning accuracy as d; Step 4: Divide the area where the target AP is located into 4 areas; Step 5: Determine the reference point by dichotomy, and collect data at the reference point; Step 6: By comparing the signal strength values, determine the area where the maximum value of the relative signal strength relationship is located; Step 7: Determine the next positioning area of the target AP; Step 8: Determine whether the area where the target AP is located reaches the expected threshold d of the positioning accuracy of the set room; Step 9: Output the coordinates of the center point of the area that reaches the expected threshold of positioning accuracy of the set room. 2. The method for locating indoor WiFi access points based on signal strength and space division according to claim 1, wherein said step 1 specifically comprises: using a wireless network scanning tool on a mobile phone to obtain the surrounding WiFi of the locator According to the scanned signal list information, determine the SSID of the target AP to be located. 3. The indoor WiFi access point positioning method based on signal strength and space division according to claim 1, wherein said step 2 specifically comprises: The locator patrols the room where the target AP may exist, and according to the change of the received signal strength RSS, the room with the largest RSS value is determined as the room where the target AP is located. 4. The indoor WiFi access point positioning method based on signal strength and space division according to claim 1, wherein said step 4 specifically comprises: Take the center point of the area where the target AP is located as the origin, divide the area into 4 areas with horizontal and vertical dividing lines, and name the 4 equally divided areas in the order of the first quadrant to the fourth quadrant for and area; i represents the number of divisions, j represents the quadrant it is in, Indicates the area where the jth quadrant is divided for the ith time; The area where the target AP is located is expressed as H _i , and i represents the number of divisions. When i=1, that is, H ₁ indicates that the first divided area is the room where the target AP is located. The length of the room is the y-axis, and the width is the x-axis. Create a two-dimensional coordinate system. 5. The indoor WiFi access point positioning method based on signal strength and space division according to claim 1, characterized in that, said step 5 specifically comprises: determining three reference points by dichotomy at the horizontal dividing line, and Use the mobile phone's wireless network scanning tool and directional antenna at different reference points to measure the RSS and direction from the reference point to the target AP. 6. The indoor WiFi access point positioning method based on signal strength and space division according to claim 1, wherein the step 6 specifically comprises: By comparing the signal strength values of the target AP measured at different reference points, the relative relationship value of the signal strength is obtained, and the area where the maximum value of the relative relationship of the signal strength is determined; The relative signal strength value refers to a large RSS value obtained by comparing RSS values in different directions at the same reference point. 7. The indoor WiFi access point positioning method based on signal strength and space division according to claim 1, wherein the step 7 specifically comprises: If the maximum value of the relative relationship of signal strength is at the position of the center point, one or more reference points are determined by dichotomy on the vertical dividing line in the direction pointed to by the maximum value, and are obtained by comparing the reference points measured on the vertical dividing line. The signal strength value of the target AP is obtained to obtain the relative relationship value of the signal strength, and the area where the maximum value of the relative signal strength relationship is determined to be the location area H _i+1 of the next target AP; If the maximum value of the relative signal strength relationship is not at the central point, the area where the maximum value of the relative signal strength relationship obtained in step 6 is located is determined as the location area H _i+1 of the next target AP. 8. The indoor WiFi access point positioning method based on signal strength and space division according to claim 1, wherein the step 8 specifically comprises: In the positioning area H _i+1 of the target AP, judge whether the area where the target AP is located reaches the desired positioning accuracy threshold of the set room, that is, judge whether (d _x <d) && (d _y <d) is true; Among them, d _x represents the maximum distance that can be moved on the x-axis with the center point of each divided area as the origin, and d _y represents the maximum distance that can be moved on the y-axis with the center point of each divided area as the origin.