Patent Publication Number: US-10768302-B2

Title: Positioning system using invisible light, sound and radio frequency signals

Description:
FIELD OF INVENTION 
     The present invention relates to a positioning system and a node network that provide the exact location of a user in indoor spaces. 
     BACKGROUND 
     In general, existing positioning systems needed to provide LBS&#39;s (Location Based Services) can be mostly classified into network-based schemes that use RF (Radio Frequency) signals from cell phone towers, schemes that use signal strengths of AP (Access Point) or Bluetooth beacons, and schemes using GPS signals. 
     Although some of these schemes are suitable in an outdoor environment where RF signals can be received well, they may not be suitable for radio shadow areas such as some indoor spaces, and may require expensive transmitters and receivers as well as extra relaying stations. In the case of schemes that use AP&#39;s (Access Point) and Bluetooth beacons, the scanning frequency of many personal devices are not frequent enough, and users may have to turn on the Wi-Fi or Bluetooth function of the device. 
     In indoor spaces where GPS signals can&#39;t reach easily, it&#39;s very difficult to provide information of facilities or objects, the best way of traveling, navigation or directories based on user&#39;s location. Measuring received signal strength of different signaling devices that have different signal strength can lower the accuracy and requires periodic surveys of AP&#39;s and beacons in the area. 
     With regards to similar positioning systems, a reference called “Three-dimensional spatial localization apparatus using sound wave or ultrasonic wave propagation time” in Korea Patent Publication No. 10-2005-0095401 exists. 
     BRIEF SUMMARY OF THE INVENTION 
     Objective 
     The objective of the present invention is to provide a terminal and a node network that can provide the accurate location of the user in indoor spaces. 
     Solutions 
     In order to the above objective, the present invention utilizes; a receiver that detects one or more signals from nodes that transmit invisible light, sound, and RF signals each with the same intensity containing location information of each nodes; a controller that determines the location of the user from the location information contained in one of more invisible light, sound, and RF signals as well as the intensity of these signals. 
     In addition, the present invention includes; a transmitter on a terminal device that sends a location request signal to signaling nodes that will transmit invisible light, sound, and RF signals containing unique ID, latitude, longitude, altitude, channel information, time of transmission, ID of position requesting device, etc.; detectors for invisible light, sound, and RF signals on the terminal device that receive signals from one or more nodes that transmit invisible light, sound, and RF signals each with the same intensity on different channels; and a controller that calculates the terminal&#39;s position from one or more invisible light, sound or RF signals that were detected. 
     Advantages of the Invention 
     As described above, the present invention has an advantage of calculating the user&#39;s location by utilizing at least one of invisible light, sound, and light. 
     Additionally, the node network of the present invention transmits signals only when there&#39;s a request from a terminal which can save a great deal of electricity. The present invention can calculate the user&#39;s location from ratios of the intensity of invisible light, sound, and RF signal and doesn&#39;t rely on timers or synchronization of timers on different devices. Since, all signaling nodes transmit signals with the same strength, the present invention also doesn&#39;t require periodic area surveys of signals nor relies on the specific signal strength data of each signaling devices. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view showing a map and nodes that is provided to the terminal according to an embodiment of the present invention. 
         FIG. 2  is a view showing a user on a map displayed on the terminal according to an embodiment of the present invention. 
         FIG. 3  is a block diagram of a terminal according to an embodiment of the present invention. 
         FIG. 4  is a block diagram of a signaling node according to an embodiment of the present invention. 
         FIG. 5  is a flowchart for the method of providing the location information according to an embodiment of the present invention. 
         FIG. 6  is a view showing the transmitter sending a location request signal to signaling nodes and receiving invisible light, sound, and RF signals from signaling nodes according to an embodiment of the present invention. 
         FIGS. 7 to 14  are diagrams that are illustrating methods to calculate the user&#39;s position using the received signal strength values of invisible light, sound or RF signals according to an embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE KEY COMPONENTS 
       100 : terminal  110 : terminal controller 
       120 : display  130 : wireless communication unit 
       140 : invisible light sensor  150 : RF transmitter 
       160 : RF receiver  170 : terminal timer 
       180 : sound receiver  190 : input 
       200 : signaling node  205 : main Body 
       210 : node controller  220 : node wireless/wire communication unit 
       230 : node timer  240 : RF receiver 
       245 : RF transmitter  250 : sound transmitter 
       260 : sound reflector 
     DETAILED DESCRIPTION OF THE INVENTION 
     Detailed descriptions of the present invention with reference to accompanying drawings are described hereafter. It is to be understood that repeated descriptions, notices, and unnecessarily detailed explanation that may obscure the purpose of the present invention are omitted. It is also to be understood that descriptions of the present invention are provided to give more complete explanation to a person of ordinary skill in the art. Therefore, the shape and size of the elements in the drawings may also be exaggerated for clearer explanation. 
     As mentioned above, the goal of the positioning system of the present invention is to accurately obtain the current position of a user in outdoor or indoor spaces. In order to achieve this goal, the present invention proposes a network of nodes with one or more signaling nodes, where a portable terminal that a user carries can determine the current position based on signals transmitted from signaling nodes. The basic concept of the node network of the present invention is described in  FIGS. 1 and 2  below. 
       FIG. 1  is a view showing a map and signaling nodes that is provided to the terminal device according to a preferred embodiment of the present invention. As shown in  FIG. 1 , one or more signaling node  200  can be installed in the space. As described above, the present invention is characterized by receiving signals from signaling nodes  200  and determining the user&#39;s position from signals received. 
     However, unlike outdoor spaces, indoor spaces may be obstructed by walls and other materials that may cause decrease in signal strength from signaling nodes  200 . Therefore, signaling nodes  200  may be installed in great number in tight spaces such as the area  950 ,  954 ,  956 , and  960  or installed in relatively small number in big spaces such as the area  961  and  962 . 
     One or more signaling nodes  200 , that were installed as describe above, transmit repeated signals with the same intensity when they receive a location request signal. Signals transmitted by a signaling node  200  can be invisible light, sound wave or RF signals. And, these signals can include ID and location information of the each signaling node. In other words, based on the characteristics that all emitted signals from one or more signaling devices  200  at a fixed position have an equal intensity, the user can determine his or her position when the user receives signals transmitted from one or more signaling nodes  200 , by utilizing the received signal strength and the location information of each signaling nodes. This characterizes the basic concept of a node network according to an embodiment of the present invention. 
     For example, if the user is located in the area  957 , the portable terminal  100  will receive signals from nodes in the area  957  along with signals from adjacent areas such as  955 ,  956  and  958 . In such a case, the intensity of signals from nodes in the area  957  will be relatively high and the intensity of signals from nodes in the area  955 ,  956 , and  958  will be relatively low, which leads to a clue that the user is in the area  957 . Furthermore, the user can also determine even more specific position based on the received signal strength and coordinates of signaling nodes through a pre-programmed algorithm with the terminal  100 . More detailed description will be described with reference to  FIG. 3  below. The current position of the user can now be displayed on the display  120  of the terminal  100  as shown in  FIG. 2 . 
       FIG. 3  is a block diagram of the terminal  100  according to a preferred embodiment of the present invention. As noted above, the terminal  100  serves the purpose of providing user&#39;s position who carries the terminal  100  based on signals transmitted from one or more signaling nodes  200 . To attain this end, the terminal  100  can include a terminal controller  110 , a display  120 , a wireless communication unit  130 , an invisible light sensor  140 , a RF transmitter  150 , an RF receiver  160 , a terminal timer  170 , a sound receiver  180 , and an input  190 . Hereinafter, descriptions are made for each of the components included in the terminal  100 . 
     The terminal controller  110  serves a function to determine the position of the user carrying a device of the present invention based on received signals transmitted from one or more signaling nodes. Before this procedure is performed, a process is made to transmit a location request signal through the RF transmitter  150  to be received by one or more signaling nodes. 
     Signals transmitted from one or more signaling nodes mentioned above include location information of the signaling node that transmitted the signal. As described previously with reference to  FIG. 1 , signals received from one or more signaling nodes can be either invisible light, sound or RF signal. Invisible light signals can be detected by the invisible light sensor  140 . Sound wave can be received by the sound receiver  180 . RF signal can be received by RF receiver  160 . Since all signals from one or more signaling nodes started with the same intensity, the terminal controller  110  can measure the distance between the user and the each signaling nodes from the value of the received signal strength. 
     Additionally, when the terminal controller  110  receives either invisible light, sound or RF signals from one or more signaling nodes, the order of priority for calculation can be light signal, sound wave, and RF signal. Although the order of priority can be different according to the user&#39;s policy, it is preferable to keep the order of light, sound, and RF signal since there are differences in characteristics such as diffraction and permeability of the medium. 
     Hereafter, a description for deriving the user&#39;s position using invisible light signals with the same luminosity will be given and an embodiment of a terminal  100  receiving invisible light with the same intensity transmitted from one or more signaling nodes is described below. The term invisible light in the following description may include at least one of any infrared rays and ultraviolet rays. In other words, invisible light can be at least one of many types of lights such as near infrared ray, infrared ray, far infrared ray, near ultraviolet ray, ultraviolet ray, and far ultraviolet rays. Invisible light signal emitted from signaling nodes  200  discussed above may carry the location information of the signaling node as well as latitude, longitude, altitude, and ID of the terminal that made a request for location. 
     The invisible light signal from a signaling node carries a variety of information. Therefore, the terminal controller  110  can find out from which signaling node the light signal had been emitted, when the invisible light is detected from the invisible light sensor  140 . In addition, since the signal strength of the invisible light had a pre-determined strength, a level of decrease in signal strength can be measured by comparing the original signal strength and the received signal strength. Since the decrease in signal strength is proportional to the traveled distance, the distance between the terminal  100  and a signaling node can be determined from the signal strength received by the invisible light sensor  140 . 
     Methods to determine the user&#39;s position by the terminal controller  110  based on the number of invisible light signals detected through the invisible light sensor  140  are described hereafter. 
     Firstly, if the invisible light sensor  140  detects only one invisible light signal, as shown in  FIG. 7 , the terminal controller  110  regards the coordinates A of the signaling node as the user&#39;s position, and may draw a circle as the margin of error with the radius being the distance estimated by the received signal strength. One tick mark in the graph represents 10M. Therefore, the user&#39;s position in the graph is represented as being located somewhere within the circle with the center being at the point A and the radius being 30M. 
     The method of representation of the user&#39;s position, when the invisible light sensor  140  detects two invisible light signals, and when the received signal strength of these two signals are same or similar enough to fall within the predetermined error range, is described in  FIG. 8 . Two signaling nodes are arbitrarily called as points A and B for convenience. The user&#39;s position is then represented as a circle with A and B as points lying on the opposite ends of the circle and the diameter being the distance between points A and B as shown in  FIG. 8 . 
       FIGS. 9 and 11  are used to illustrate the method when two received signal strength are different. In  FIG. 9 , the signaling node that has a bigger signal is designated as the point A while the other signaling node as the point B. To help illustrate the method of calculation, the ratio of the two received signal strength is arbitrarily given as 1:3. In such a case, the nearest possible position of the user from the origin is at the point N (the internal division point of the line-segment AB in the ratio 1:3) lying on a straight line between A and B. The farthest possible position of the user is at the point F (the external division point of the line-segment AB in 1:3). 
     Since the user can be located outside the straight line AB, the user&#39;s position can be represented as a circle with points N and F lying the opposite ends, as shown in  FIG. 10 . 
     With regards to  FIG. 11 , if the received signal strength from A and B are denoted as sA and sB respectively, and the ratio of signals sA/sB as R, and the distance between A and B as D, then the distance between N and A is D/(R+1). And the distance between A and F is D/(R−1). 
     If the x-coordinate of B is called xB, and the y-coordinate is called yB, then the user&#39;s position, as shown in  FIG. 10 , can be represented as a circle with the center being S(−xB/(R 2 −1), −yB/(R 2 −1)) and the radius being D*R/(R 2 −1). In such a case, the coordinates for N would be (xB/(R+1), yB/(R+1) and the coordinates for F would be (−(xB/(R−1)), −(yB/(R−1))). 
     Therefore, a circle to be displayed on the terminal, when different received signal strengths are received from two signaling nodes, can be derived from the signal strength ratio and the distance between two nodes by using the Equation 1 below. 
     
       
         
           
             
               
                 
                   
                     
                       
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     If three invisible light signals are received through the invisible light sensor  140 , the signaling node with the highest intensity is indicated as A and remaining nodes as B and C. In this case, an equation of a circle can be obtained through the equation 1 based on the ratio of the received signal strength of A and B. Another equation for a circle can be obtained through the equation 1 based on the ratio of the received signal strength of A and C. 
     As shown in  FIG. 12 , the user&#39;s position are narrowed down to two intersections of two circles denoted as U 1  and U 2 . The user&#39;s position to be displayed on the terminal is represented as a circle with the center being the closer one to the previous position of the user among U 1  and U 2 , and the radius being the distance between U 1  and U 2 . In case there is no information about the previous location, a circle with U 1  and U 2  as two points at the opposite end is represented as the user&#39;s position. 
     As shown in  FIG. 13 , one of U 1  and U 2  is located inside the triangle with vertices A, B, and C, and the other outside the triangle. 
     As shown in  FIG. 14 , an equation for one more circle, based on the ratio of the received signal strength between B and C, can be obtained in addition to two circles obtained from the ratio of received signal strength between A and B as well as A and C. However, intersections of the new circle with the other two circles still remain U 1  and U 2  as shown in  FIG. 12 . (In other words, when the calculation is solely relying on the ratios of signal strength from three points while not knowing the exact distances between the user and the nodes, one cannot localize the user to a single point. This is why the equation for the circle between B and C was not necessary in paragraph  52 .) 
     When four invisible light signals detected, four circles based on the ratios of received signal strength between A and B, between A and C, between B and C, and between C and D, can be obtained yielding a single common intersection from four circles. Therefore, it is to be understood that four or more signals are needed in order to come up with the user&#39;s position with relatively high accuracy when the calculation is based on ratios of received signal strength only. 
     Above descriptions can not only used for invisible light transmitted with the same intensity, but also can be applied to one or more sound signals transmitted with the same intensity that are detected by the sound receiver  180 . Similarly, same methods can be used for one or more RF signals transmitted with the same intensity that are detected by RF receiver  160 . 
     As described above, the location-tracking method through the terminal  100  according to a preferred embodiment of the present invention has an advantage of not having to synchronize timers of each signaling nodes or the terminal  100 . Furthermore, since the present invention relies only on the received signal strength and location of signaling nodes, the terminal  100  in accordance with a preferred embodiment of the present invention does not need the value of original signal strength included in the signal or measure the time with timers. 
       FIG. 4  is a block diagram for a signaling node  200  according to a preferred embodiment of the present invention. As mentioned above, a plurality of the signaling node  200  can be installed and these signaling nodes would transmit signals carrying the location information of each one. The signal to be transmitted by these signaling nodes may be in the form of invisible light, sound, and radio waves, each of which may have the same signal strength. Additionally, these signals can be transmitted through different channels to be distinguished from each other. To attain this objective, the signaling node  200  according to a preferred embodiment of the present invention includes a main body  205  and a sound reflector  260 . In addition, the main body  205  of the signaling node  200  in accordance with a preferred embodiment of the present invention includes a node controller  210 , a wireless/wire communication unit  220 , a node timer  230 , an RF receiver  240 , a RF transmitter  245 , and a sound transmitter  250 . Hereafter, descriptions are made for a signaling node  200  according to a preferred embodiment of the present invention. 
     Node controller  210  controls the overall operation of the signaling node  200 . Node controller  210  emits invisible light signals through the invisible light transmitter  270  and transmit sound wave signals through a sound transmitter  250 . The node timer  230  is used to provide the time of transmission of the sound signal, and the RF receiver  240  is used to receive location request signals from the terminal  100 . 
     RF transmitter  245  emits RF signals to the terminal  100 . In addition, upon receiving a location request signal from the terminal  100 , the RF transmitter  245  can transmit a radio wave signal that carries data including a unique ID, latitude, longitude, altitude, channels, ID of the terminal that sent the location request, time of transmission, channel of invisible light, channel of sound signal, etc. 
     The sound transmitter  250  transmits sound wave signals to be received by the terminal  100 . In addition, the sound transmitter  250 , as with the RF transmitter  245 , can transmit signals that carry data including a unique ID, latitude, longitude, altitude, channel, time of transmission, ID of the terminal that sent a location request signal, etc. 
     The invisible light transmitter  270  emits invisible light signals to be detected by the terminal  100 . The invisible light transmitter  270  according to a preferred embodiment of the present invention, can emit an invisible light signal that carry data with unique ID of the signaling node  200 , latitude, longitude, altitude, channel, time of emission, ID of the terminal that requested the location information, etc. 
     Sound reflector  260  functions to diffuse the sound waves originating from the sound transmitter  250  in all directions. 
     The followings describe a method of providing position information in accordance with a preferred embodiment of the present invention with reference to  FIGS. 5 and 6 .  FIG. 5  is a flowchart for a method of providing location information in accordance with a preferred embodiment of the present invention. It is to be understood that repeated descriptions mentioned above and duplicates are omitted in following descriptions. 
     Firstly, at operation S 101 , user&#39;s input to request location signals is entered through the input  190  or the display  120 . Then, the RF transmitter  150  transmits a location request signal to one or more signaling nodes  200  which is denoted as operation S 103 . A location request signal transmitted at operation S 103  may include any data needed for requesting the location information. This data may include various information including the terminal ID. 
     Afterwards, operation S 105  takes place where signals transmitted from one or more signaling nodes are received. As mentioned above, signals transmitted from one or more signaling nodes may be in the form of invisible light, sound, and RF signal, which have the same signal strength. In order to distinguish which signal was transmitted from which signaling node, these signals are sent through different channels. In case invisible light or sound signals are too weak that data such as latitude, longitude, altitude, etc. can&#39;t be discerned and only the channel and the received signal strength can be recognized, channel information of invisible light and sound signals can be included in the RF signal in addition. 
     Operation S 107 , that determines whether a sound signal is received through the sound receiver  180 , is performed afterwards. If the sound wave is received, the process advances to operation S 109  and calculate the terminal&#39;s position on the basis of sound signals. If not, the process goes to operation S 111  to determine if invisible light signals are detected. 
     If all three signals are detected as the user operates the device, it&#39;s possible to use any preferred medium to obtain the position information. The location of the terminal can be traced through, preferably in the order of, invisible light, sound wave, and radio wave. 
     Operations S 109 , S 113 , and S 115  are stages to calculate the location of the terminal that user carries based on invisible sound, light, and RF signals respectively. Since descriptions of these processes were made above, description thereof will not be repeated. 
     Afterwards, operation S 117  is performed which will output the position data calculated through operation S 109 , S 113  or S 115 . 
       FIG. 6  is a view showing a terminal transmitting a location request signal to signaling nodes and receiving invisible light, sound, and RF signals from signaling nodes in return. To be more specific,  FIG. 6  illustrates an example where the terminal  100  receives any one among invisible light, sound, and RF signals from the four signaling nodes  200   a,    200   b,    200   c,  and  200   d.    
     Under the assumption that the signaling nodes ( 200   a,    200   b,    200   c,  and  200   d ) shown in  FIG. 6  transmit invisible light, sound, and RF signals each with the same signal strength, the terminal controller  110  measures the received signal strength between the terminal  100  and each signaling nodes ( 200   a,    200   b,    200   c,  and  200   d ) to calculate the position of the terminal  100 . 
     The terminal controller  110  in accordance with a preferred embodiment of the present invention calculates the position of the terminal  100  based on at least one out of three media among invisible light, sound, and RF signals which were transmitted upon receiving a location request signal. Since the methods to track the user&#39;s location through the above signals were described in detail previously, descriptions for these methods will be omitted. 
     Although a preferred embodiment of the present invention has been described in detail, it will be understood that the scope of the present invention is not limited to the above described embodiment, and any variations and modifications by a person having ordinary skill in the art using the basic concept and spirit defined in following claims are within the scope of the present invention.