KR101044522B1 - Position recognition system and position recognition method - Google Patents

Abstract

The present invention relates to a location recognition system, and more particularly, to a Real Time Locating System (RTLS) based on a wireless LAN such as Wi-Fi and applying a wireless positioning technology, which is a core technology for determining a location.

Location recognition system of the present invention, the access point which is a fixed facility for wireless LAN communication; A mobile terminal for calculating a reception sensitivity of a signal transmitted from the access point; And a location calculation server that receives the reception sensitivity from the mobile terminal through the wireless LAN communication and calculates a location of the mobile terminal.

RTLS, location aware, wifi, AP, wi-fi

Description

POSITION RECOGNITION SYSTEM AND POSITION RECOGNITION METHOD}

The present invention relates to a location recognition system, and more particularly, to a Real Time Locating System (RTLS) based on a wireless LAN such as Wi-Fi and applying a wireless positioning technology, which is a core technology for determining a location.

In the present invention, in determining the location using a wireless communication network, the location and location of a wireless communication access point (AP) constituting a wireless LAN infrastructure is selected and the terminal uses the sensitivity of received signals received from the access point (AP). The RTLS is implemented by applying the location determination algorithm using the information.

Location-based service (LBS) is a location-based service that combines personalization and mobility, which is a characteristic of the wireless Internet, and uses location information-based systems and services that collectively utilize mobile communication networks such as mobile phones and PDAs and IT technologies. Say.

The service is based on the customer's location information of the convenience of life (logistics, services of convenience, telephone number service, local information), commerce information (providing services such as notification of the desired product, location-based marketing / advertising, etc.), Traffic information (driving review information, public transit route search and setting) and location tracking information (location tracking, personal location information, lost terminal tracking) can be used to provide a variety of information throughout life.

In the location-based service, a method of recognizing a location of a movable target is performed. In order to recognize the position of the object that can be moved, a fixed object that is a reference for position determination is required. In the current location recognition method, a stationary satellite or a beacon signal transmitter for location recognition is used as a fixed object as a reference for location determination.

It is an object of the present invention to provide an inexpensive location-aware system without the additional cost of having a fixed facility on which to determine location.

In addition, another object of the present invention is to provide a location recognition system that can ensure sufficient precision while being less affected by the terrain.

Location recognition system of the present invention for achieving the above object, the access point is a fixed facility for wireless LAN communication; A mobile terminal which calculates and transmits a reception sensitivity of a signal transmitted from the access point, switches to a sleeping mode, and wakes up in the sleeping mode when a preset wake-up condition is satisfied; And a location calculation server that receives the reception sensitivity from the mobile terminal through the wireless LAN communication and calculates a location of the mobile terminal.

Preferably, the access point may be a facility supporting Wi-Fi type wireless LAN communication, and the signal transmitted from the access point for calculating the reception sensitivity may be a beacon signal broadcast by the access point periodically.

Preferably, the location calculation server may transmit the calculated location to the mobile terminal through the wireless LAN communication so that the user of the mobile terminal can recognize its location.

A location recognizing method performed in the location recognizing system configured to achieve the above object comprises: receiving beacon signals from a plurality of access points in the mobile terminal; Calculating reception sensitivity of the received beacon signals in the mobile terminal; Transmitting the beacon signals and their received sensitivity values from the mobile terminal to a location calculation server; And calculating, by the location calculation server, the location of the mobile terminal using the beacon signals and their received sensitivity values.

By implementing the position recognition system of the present invention according to the above configuration, there is an advantage that can reduce the additional cost for having a separate fixed equipment as a reference for position determination.

1 illustrates an infrastructure component of a location based service system using GPS.

The Location-Based Service Platform (LBSP) is a platform that provides the most basic and core functions for LBS, and provides a common component that facilitates the development of various location-based services. In detail, external LBS application service client location request processing, interworking with the location-related system (base station or GPS location acquisition server) in the mobile communication network, primary processing (location transformation or Reverse-Geocoding, etc.) of the location information obtained from the location acquisition server, Location information management and spatio-temporal function support are provided.

The Mobile Positioning Center (MPC) is a server that serves as an element for retrieving, transmitting, storing, and controlling location data in a location information providing network infrastructure. GISP (Geographic Information Service Platform) is a GIS platform or content server that provides contents such as electronic maps, POIs, and traffic information for LBS services.

AS (Application Server) / SP (Service Provider) is an LBS application service providing server or an LBS client / service provider that provides LBS supplementary application services based on location information or GIS content provided by LBSP or GISP.

CP (Contents Provider) is a source provider of electronic maps, POIs, road network information, etc. mounted in GISP, and provides additional contents such as real-time traffic information, weather information, merchant information, and representative POIs.

Positioning Determining Entity (PDE) is an element that determines the precise location or geographic location of a wireless terminal when a mobile terminal user initiates or talks. All PDEs provide one or more positioning techniques.

The main advantage of the location-based service system shown is that wireless Internet users do not have to enter addresses or area separators while moving multiple locations, and GPS positioning technology enables this to facilitate access to wireless Internet services. Is one of the techniques. In addition, as the LBS system is gradually developed, it is being developed as a system that uses a combination of the GPS method and the Cell-ID method.

The Cell-ID method uses a mobile communication base station to locate a user within a 500 ~ 1500m error range around a base station connected to a subscriber. Therefore, while the location of the building and the underground can be found using a repeater, etc., the disadvantage is that the error range is wide and only the approximate location can be determined.

GPS method can find the exact position within 10 ~ 150m error because satellite finds GPS chip accurately, so it can track the location more precisely than Cell method. However, due to the nature of the satellite signal, it cannot be used indoors and is reflected in buildings. Because of its good refraction, it is vulnerable to high-rise buildings.

Therefore, when looking at the problem of the LBS system of Figure 1, it is difficult to use in a poor communication environment, such as the indoor state. In addition, the error of positioning can be reduced from 10m to 50m by using a mobile phone with GPS, but the reception is inferior to the base station method. In addition, since it takes two to three minutes to receive the initial information, commercialization has many difficulties.

And base station, various management server, home location register, exchange, etc. must be separately installed, and the transmission and management system through this is complicated. This increases the separate installation space and the associated costs.

In the present invention, based on the Wi-Fi wireless LAN, RTLS (Real Time Locating System) was implemented by applying a radio positioning technology that is a core technology for determining the location.

In the present invention, in positioning and tracking using a wireless communication network, the location of the access point (AP) is selected and identified as a wireless communication transmitter, and the mobile terminal uses the received signal received from the access point (AP). RTLS can be obtained by obtaining the distance information and applying the information to a predetermined positioning algorithm. In this case, it is preferable to apply 802.11b among 802.11 established by IEEE as a standard WLAN protocol.

First, the Wi-Fi system that can be applied to the location-based service according to the present invention will be discussed.

The contents of the IEEE 802.11b standard fall into two broad categories. One is related to authentication of WLAN and defines SSID (Service Set IDentifiers). The SSID refers to the network name of the device in the WLAN subsystem to perform initial access control. An AP (Access Point), which connects a wired LAN and a wireless terminal, broadcasts its SSID in a beacon signal periodically sent by itself.

The other is that of security, it defines WEP. WEP is an encryption scheme defined to provide security of WLAN data streams in IEEE 802.11b. It is a symmetric structure using the same key and algorithm for encrypting and decrypting data. The purpose of the WEP is to provide access control and confidentiality, allowing only users with the correct WEP key to access the network and decrypting the data stream.

The operation mode of 802.11b can be classified into two types: infrastructure WLAN (client / server method) and ad-hoc peer-to-peer method (WLAN). The present invention is more preferably applied to infrastructure WLAN. Do.

Infrastructure WLAN is a structure including AP, a control terminal for managing registration and media access of terminals belonging to a communication network and supporting communication with other communication networks. It also supports medium access control (MAC).

Each mobile terminal used in the wireless LAN system includes a wireless LAN card, which provides a transparent connection to a network by performing an interface function between a network operating system (NOS) and an antenna in a wireless LAN environment.

The access points (APs) are LAN hubs in a wireless environment. For example, it is connected to a backbone of a wired network through a standard Ethernet cable to communicate with RTLS terminals (or tags) through an antenna. The radius of the AP ranges from 30 to 1000m, and one AP supports dozens or hundreds of RTLS terminals depending on the technology, configuration and usage. It also tracks the movement of RTLS terminals within its own area and may approve or reject communication of specific RTLS terminals. Recently, APs that combine router functions or support high-speed Internet connections such as ADSL and Cable Modem have also been released.

2 illustrates a structure of a location recognition system according to an embodiment of the present invention.

Location recognition system according to an embodiment of the present invention, the access point which is a fixed facility for wireless LAN communication; A mobile terminal for calculating a reception sensitivity of a signal transmitted from the access point; And a location calculation server that receives the reception sensitivity from the mobile terminal through the wireless LAN communication and calculates a location of the mobile terminal.

If the Wi-Fi technology is applied to the location recognition system, as shown, the access point is a Wi-Fi AP 200, the mobile terminal is a RTLS terminal 100 for Wi-Fi, and the location calculation server is an RTLS server 340 The location recognition system may be implemented by RTLS. In addition, the RTLS may include a Wi-Fi support server 360 as a LAN server for supporting wireless LAN communication.

That is, as one embodiment according to the spirit of the present invention, RTLS based on a WiFi WLAN may be implemented. The Wi-Fi WLAN-based RTLS may be used, for example, to track the location of a parked or moving vehicle.

APs that support the use of Wi-Fi-based wireless Internet in certain areas are typically installed to capture beacon signals from three or more APs at one point, so triangulation can be applied without the need for additional devices. Can be. On the other hand, in the case of a mobile terminal base station installed so that two or less base station signals are caught at one point, it is difficult to use a triangulation method.

3 illustrates an embodiment of an RTLS tag type RTLS terminal that can be used in the location recognition system of the present invention.

The illustrated RTLS terminal has one or two or more antennas (and connectors thereof) 20 for receiving wi-fi signals. When two or more receiving antennas are provided, the antennas may be divided into a receiving antenna and a transmitting antenna, or may be applied in a diversity structure through the switch block 30 to cover a wider location, or may be applied to different APs. It can be applied to receive a signal for.

The main processor 10 may be a single processor that performs a function of measuring a reception sensitivity of the beacon signal and packaging information including the reception sensitivity and an identification symbol of the base station. That is, the main processor 10 may perform an operation of packaging the information including the reception sensitivity and the identification symbol of the base station as a receiver using an RTLS server existing on the Internet as a receiver.

The illustrated RTLS terminal employs a one-chip solution device 10 having an 802.11b MAC terminal and a 2.45 GHz RF block, and has a PA 46 for additional transmission output. In addition, both the Rx path and the Tx path are implemented to remove out-of-band components through bandpass filters 42 and 44 for 2.45 GHz WLAN.

For various applications executed using the RTLS terminal in the RTLS terminal, at the position of the block shown by the sensor unit 54, a temperature sensor, a movement sensor (Tilt / Vibration Sensor), a button (for example, a Push Button) or a magnetic It can be implemented to have a device having a coil (Magnetic Coil) function.

In addition, various user interfaces 56 may be provided to support the various applications, and additional memory 52 may be further provided to support applications requiring a large memory capacity.

Referring to the operation of the RTLS shown in FIG. 2, the APs 200, 201, and 202 periodically transmit a beacon signal including the identification information (eg, SSID) on the AP's own Wi-Fi network to the RTLS terminal 100. Broadcast (packets). Accordingly, the beacon signal may be analyzed to identify which AP is being broadcast.

Next, the RTLS terminal 100 receives the SSIDs of each of the APs 200, 201, and 202 from a plurality of APs (at least three APs when using the triangulation method), and receives the RSSI of each SSID. Indication) value is calculated.

The RTLS terminal 100 transmits the SSID and RSSI values of the APs 200, 201, and 202 to the AP connected to the AP (assuming AP 200) again as a LAN bridge. The AP support server 320 receiving the data from the LAN bridge AP 200 transmits the received data to the RTLS server 340. The RTLS server 340 determines the location of the RTLS terminal 100 that transmits the received data. For example, a triangulation method may be applied to SSIDs and RSSI values of at least three APs 200, 201, and 202 to determine the location of the RTLS terminal 100. Thereafter, the RTLS server 340 may transmit the determined position value to the RTLS terminal 100 via the AP support server 320 and the LAN bridge AP 200.

The RTLS server 340 calculates the position of the RTLS terminal 100 from reception sensitivity values of beacon signals transmitted from the RTLS terminal 100 according to the spirit of the present invention.

The position calculation may include a process of estimating distance based on a received sensitivity value and calculating a position by triangulation.

Triangulation is a geometric method that is most commonly used in RTLS to estimate the real-time position of a moving object on a two-dimensional plane. At least three reference points are required to estimate the real-time position of a moving object on a two-dimensional plane.

Therefore, if the triangulation method is used in the position recognition method according to the spirit of the present invention, beacon signals broadcast from at least three APs should be received.

4 is a distance for measuring the position from the three reference points expressed as d1, d2, d3. The distance from each reference point to the target point for position measurement may be calculated by Pythagorean theorem of Equation 1 below.

d ₁ ² = (xx ₁ ) ² + (yy ₁ ) ²

d ₂ ² = (xx ₂ ) ² + (yy ₂ ) ²

d ₃ ² = (xx ₃ ) ² + (yy ₃ ) ²

In the case of using triangulation and radio signal strength information (RSSI), the distance d between the moving object (RTLS terminal) and the reference point AP may be obtained through the Friis formula of Equation 2 below.

λ is the wavelength of radio waves, c is the speed of radio waves, f is the frequency, and L is the transmission loss (ie, received signal strength) of the signal transmitted by the mobile entity. The transmission loss of the transmitted signal is obtained by the difference between the signal transmission strength of the mobile object and the strength of the received signal at the reference point.

In order to calculate the location of the RTLS terminal, in addition to the triangulation method mentioned in the above equations, radios such as Time of Arrival (TOA), Time of Flight (TOF), Time Difference of Arrival (TDOA), and Angle of Arrival (AOA) Positioning techniques can also be applied.

The reception sensitivity value decreases as the distance increases, and the reception sensitivity value may be weakly measured even when the distance is not far due to an obstacle such as a wall or a building. This phenomenon may cause an error in the position calculation of the RTLS server according to the spirit of the present invention.

There are two ways to prevent the error.

In the first method, the RTLS server retains data on a region where an error with respect to a reception sensitivity value occurs in a database, and searches the database every time the position calculation is performed based on the reception sensitivity value. Check and correct. For correction, the database may have a data structure that stores identifiers of the AP detected in the area where an error occurs and its reception sensitivity values, and maps the location information measured in each case.

The second method is to predict the occurrence of an error according to an algorithm applying a predetermined path loss model. Path loss models include simple path loss model, wall attenuation model, and layer attenuation coefficient model. The most known outdoor path loss model is the Okumura-Hata model, which is an empirical formula that measures the actual urban environment.

FIG. 5A illustrates a location recognition method performed in the RTLS of FIG. 2.

According to the illustrated location recognition method, first, the RTLS terminal 100 includes: receiving beacon signals from a plurality of access points (S110); Calculating reception sensitivity of the received beacon signals (S120); And transmitting the beacon signals and their received sensitivity values to a location calculation server (S130).

The RTLS server 346, which has received the beacon signals and the received sensitivity values of step S130, calculates the position of the RTLS terminal 100 using the received data (S140), and calculates the calculated RTLS terminal 100. ) Is transmitted to the RTLS terminal 100.

The illustrated RTLS terminal 100 receives SSIDs of at least three APs 200, 201, and 202, but performs data transmission / reception with the RTLS server 340 through one AP 200. That is, the RTLS terminal 100 selects one AP 200 having the most communication efficiency and performs wireless LAN communication. The RTLS terminal 100 may be connected to the RTLS server 346 through a wireless LAN communication and an internet network.

To this end, the RTLS terminal 100, after the step S110, may further comprise the step of connecting with one of the plurality of APs for wireless LAN communication.

On the other hand, in order to reduce the manufacturing cost of the RTLS terminal used in the location recognition system, the RTLS terminal has a simplified structure to perform only a function of transmitting the reception sensitivity values of the beacon signal of the AP 200 to the RTLS server 340. Can be configured. An RTLS terminal with the simplified function may be referred to as an RTLS tag.

In addition, the Wi-Fi RTLS terminal is a requirement for a mobile terminal that performs the Internet, and it is desirable to minimize power consumption. If the location recognition method according to the spirit of the present invention is performed too frequently, the power consumption is increased, resulting in a decrease in battery life.

In order to prevent the above problem, a location recognition method of a method of adjusting the time point for performing location recognition according to the spirit of the present invention can be implemented. 5B illustrates operations centering on the RTLS terminal for Wi-Fi performing this location recognition method.

The illustrated method is a method of adjusting a cycle of waking up and sleeping the RTLS terminal according to an executed application.

The method includes the steps of initializing the RTLS terminal (S10); Scanning SSIDs broadcast from a plurality of APs (S20); Transmitting the scanned SSIDs and their reception sensitivity to an external RTLS server in a UDP manner (S30); Sleeping the RTLS terminal (S40); And determining a wake-up condition for the RTLS terminal (S50), and if the condition is satisfied, waking up the RTLS terminal (S60).

When implemented as an RTLS terminal, the RTLS terminal has its own location value, and notifies the user of this, or implements such as car navigation, the location value calculated from the RTLS server after the step S30 and before the step S40. The method may further include receiving.

As shown in FIG. 5B, the main basic operation of the RTLS terminal initialized by the user's power-on operation or the like (S10) performs an operation of scanning the SSID to detect the SSID sent from APs around the terminal (S20). And the scan result of the SSID is transmitted to the RTLS server in UDP (user datagram protocol) format (S30). Here, UDP is a method in which only a data is transmitted from a transmitting side when information is exchanged with each other on a network, that is, a method of transmitting data unilaterally from a transmitting side without going through a connection procedure with a receiving side.

In the step S50 shown in the drawing, the condition for granting a condition for waking up the RTLS terminal is a method of periodically waking up using a timer, and wakes up when a motion of the RTLS terminal is detected using a motion sensor. The method may include a method of waking when a predetermined signal (an RF signal from an RF reader of an RFID system) is applied from the outside.

Although the technical spirit of the present invention has been described in detail according to the above-described preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

1 is a structural diagram showing the components of a location-based service system using GPS.

2 is a structural diagram showing a structure of a location recognition system according to an embodiment of the present invention.

3 is a block diagram illustrating one embodiment of an RTLS terminal that may be used in a location aware system of the present invention.

4 is a conceptual diagram for explaining the principle of triangulation.

5A is a flowchart illustrating a location recognition method performed in the location recognition system of FIG. 2.

FIG. 5B is a flowchart illustrating operations based on the RTLS terminal provided in the RTLS terminal for Wi-Fi performing the location recognition method of FIG. 5A; FIG.

Claims (9)

A plurality of access points which are fixed facilities for wireless LAN communication; After calculating and transmitting the reception sensitivity of the signals transmitted from the plurality of access points, the mobile terminal switches to the sleeping mode and wakes up in the sleeping mode when a preset wake-up condition is satisfied. ; And And a location calculation server that receives the reception sensitivity from the mobile terminal through the wireless LAN communication and calculates a location of the mobile terminal, wherein the mobile terminal is received from at least three access points of the plurality of access points. Calculate the received sensitivity of the signal to be transmitted to the location calculation server, connected to any one of the plurality of access points, and transmits to the location calculation server through any one access point, The location calculation server calculates the location of the mobile terminal using the reception sensitivity of the at least three access points and the location of the at least three access points, and calculates the location of the mobile terminal through the one of the access points. Location recognition system provided to the mobile terminal. The method of claim 1, The location calculation server, And calculating the distance between the access point and the mobile terminal from the reception sensitivity. delete The method of claim 1, The access point, the location recognition system, characterized in that for supporting the wireless LAN communication. The method of claim 4, wherein The location calculation server, the location recognition system, characterized in that for transmitting the calculated position value to the mobile terminal via the wireless LAN communication. The method of claim 1, And the signal transmitted from the access point for calculating the reception sensitivity is a beacon signal broadcast by the access point periodically. delete delete delete

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