Estimating the arrival direction of a radio signal

Abstract

A method for estimating a direction from which a radio signal was received, in particular within the room, in particular within the sales room (2) or storage room, wherein the method comprises the following computerized steps: • defining at least two at different known positions located receiving devices (16 - 24) for receiving a radio signal that is being sent out from a movable sending device (27), • estimating the direction from which the radio signal was received based on representations of the reception signal strength delivered by each of the at least two receiving devices as a result of receiving the radio signal at both of the at least two receiving devices.

Description

[0001] TP0555

[0002] TITLE

[0003] ESTIMATING THE ARRIVAL DIRECTION OF A RADIO S IGNAL

[0004] DESCRIPTION

[0005] TECHNICAL FIELD

[0006] The invention relates to a method and a system for estimating the arrival direction of a radio signal .

[0007] BACKGROUND

[0008] In retail or logistics , one of the technical challenges of indoor navigation is the identi fication of a direction from which the radio signal is received or in other words the identi fication of a direction from which the radio signal was sent out . A possible approach would be to distribute a larger number of special detection devices , which are configured for detecting the direction from which the radio signal is received . In technical j argon such special devices are termed "angel o f arrival" detector, in short AoA detector . Such an AoA detector comprises an antenna array and the electronics of such an AoA detector is configured for measuring the time di f ference of arrival of a radio signal ( TDOA) between individual elements of the antenna array . Hence , signal proceeding performance and highly synchroni zed processing of the individual received radio signals at di f ferent antennas are crucial .

[0009] Data generated by each induvial AoA detector must be sent via a data communication network, either by radio or line , to a central processing unit where these data are further processed to support the indoor navigation . Hence , the use of AoA detectors amongst TP0555 2 already exiting electronic retail equipment demands a further layer of electronic equipment , which must be installed, maintained and managed to include the AoA detectors . These circumstances are a signi ficant cost driver .

[0010] In conclusion, in retail or logistics the application of stand-alone AoA detectors and the use of data generated by it requires an extremely expensive separate infrastructure . Notwithstanding the high investments the results achieved by the AoA detectors have shown to suf fer from multipath and shadowing problems and may cause large locali zation error, which in turn leads to misleading navigation instructions causing frustration of the users of such technology .

[0011] Therefore , the obj ect of the invention is to provide an improved method and a system for identi fying or estimating, respectively, a direction from which the radio signal was received, which can easily be used within a retailer' s sales room or a storage room, etc . and delivers results with suf ficient accuracy .

[0012] SUMMARY OF THE INVENTION

[0013] This obj ect is achieved by a method for estimating a direction from which a radio signal was received according to claim 1 . Therefore , the subj ect matter of the invention is a method for estimating a direction from which a radio signal was received, preferably within a room, particularly preferably within a sales room or a storage room, wherein the method comprises the following steps : computeri zed defining at least two receiving devices for receiving a radio signal that is being sent out from a sending device , wherein the at least two receiving devices are located at di f ferent known positions , in particular within the room, in particular within the sales room or storage room, and the sending device is movable , and computeri zed TP0555 3 estimating the direction from which the radio signal was received based on representations of the reception signal strength delivered by each of the at least two receiving devices as a result of receiving the radio signal at both of the at least two receiving devices , or based on a representation of the reception signal strength delivered by a first of the at least two receiving devices and either a lack of another presentation from a second of the at least two receiving devices as a result of non-reception of the radio signal or a message from the second of the at least two receiving devices , which message indicates the non-reception of the radio signal at the second of the at least two receiving devices .

[0014] This obj ect is al so achieved by a first use of a sending device in the method according to the invention . Therefore , the subj ect matter of the invention is also a use of the sending device in said method, wherein the sending device comprises at least two antennas , pre ferably exactly two antennas , for sending the radio signals .

[0015] This obj ect is al so achieved by a second use of a sending device in the method according to the invention . Therefore , the subj ect matter of the invention is also a use of the sending device in said method, wherein the sending device executes the steps of the method according to the invention .

[0016] This obj ect is al so achieved by a use of a receiving device in the method according to the invention . Therefore , the subj ect matter of the invention is a use of a receiving device in said method, wherein the receiving device comprises at least two antennas , pre ferably exactly two antennas , for receiving the radio signal .

[0017] This obj ect is al so achieved by a system that is configured to perform the method according to the invention . Therefore , the subj ect matter of the TP0555 4 invention is also a system for estimating a direction form which a radio signal was received, wherein the system is configured to perform the method according to the invention .

[0018] The measures according to the invention provide the advantage that special devices like supplemental AoA detectors which comprise a dedicated antenna array and high-performance electronics for synchroni zed processing of the radio signal received at such antenna array is completely avoided .

[0019] In fact , already existing electronic equipment comprising a receiver for receiving the radio signal can be used as the receiving device for the estimation of the direction from which the radio signal was received . An update of the already existing infrastructure only requires changes to the existing software that controls the receiving devices and processes the estimation for the direction . This means that a software of the receiving devices only needs to be adapted to make them understand that they should receive the radio signal from the sending device . I f the radio signal is received the software modi fication of the receiving devices provides that the receiving devices will deliver their representation of the reception signal strength . Otherwise , in case that the radio signal is not received - dependent on the actual implementation of the method - the respective receiving device will not deliver such a representation or will deliver a message that indicates the lack of reception of the radio signal from the sending device . Such a software update can easily be implemented with new equipment or even be updated in existing equipment by means of an over the air update , because a radio communication infrastructure for such receiving devices already exists within the room, for example the sales room or the storage room . TP0555 5

[0020] Further to this , the existing radio communication infrastructure can be used for the computeri zed defining of the at least two receiving devices out of the existing receiving devices that are already managed withing the exiting communication infrastructure . The so created group of receiving devices used for estimating the direction now forms a receiving means of a "virtual angel of arrival detector" as each of the receiving devices comprises an antenna that is used for receiving the radio signal at its actual position in space . The plurality of antennas of the receiving devices substitutes the antenna array of known AoA detector . In contrast to the miniaturi zed form factor of the known AoA detector the plurality of antennas embedded in the group of the receiving devices is distributed in space ( in the room) in accordance with the spatial positions at which the receiving devices of the group of receiving devices are located . The distance between the at least two antennas , each of which is comprised in the respective receiving device , used for the estimation of the direction is much larger as it is the case for known AoA detectors .

[0021] Further to this , also the paradigm of highly synchroni zed processing of the radio signals received at the antenna array of the known AoA detector is given up . The receiving devices can be operated in accordance with their typical operation scenario - for example in an alternating operation between an energy-saving sleep-mode , which is characteri zed by a low or virtually no energy consumption, and an active-mode , which is characteri zed by increased energy demand . Only during the active-mode , the receiving devices are ready to receive the radio signal while during the sleep-mode the receiving devices lack signal receiving readiness . Hence , only during the active-mode the receiving devices receive the radio signal . But it is of no signi ficance that the reception of the radio signal is TP0555 6 synchroni zed between the receiving devices . The same applies to the processing of the received radio signal within the receiving devices to derive the representation of the reception signal strength . The same applies also to the delivery of the representation of the reception signal strengths for further processing to estimate the direction . Communication systems that comprise such an alternation between the sleep-mode and the active-mode are well known . As an example , reference is made to the published international patent application WO 2015 / 124197 Al or the well-known Bluetooth ® Core Speci fication Version 5 . 4 , Periodic Advertising with Response , both technologies are already applied in retailer' s environments to drive so termed electronic shel f labels . Typical ly, the electronic shel f labels are part of a radio communication infrastructure , and their functions are controlled by radio signals that convey data or commands . A computer delivers the data or commands via access points to the respective electronic shel f labels .

[0022] The sending device may be freely movable , for example by a person, or movable together with a further movable device to which it is attached, for example a shopping cart or a cargo sled or a pallet j ack or a forkli ft or the like . The sending device may be permanently operated to send out the radio signal for the estimation of the direction or it may be computeri zed controlled, for example via the existing radio communication infrastructure , to send out its radio signal for the estimation of the direction only during certain periods of interest , which may be of advantage to reduce radio channel occupation and / or power consumption .

[0023] Each involved ( grouped) receiving device executes its task of receiving the radio signal and generating the representation and delivers the representation in TP0555 7 accordance with its individual sleep-mode and activemode cycling .

[0024] The same applies to each involved receiving device that lacks reception of the radio signal for estimating the direction and as consequence of this does not deliver any representation or delivers only the message that indicates the lack of reception of the radio signal .

[0025] Between involved receiving devices the delivery of the representations or otherwise the representation and the message delays of up to a few single digits of seconds are acceptable . This delay is considered acceptable because the sending device is typically moved at very low speed - for example the typical human walking speed or less . In particular, i f the signal is sent and / or received within the room like the sales room or the storage room this delay is further considered acceptable because the geometry or topology, respectively, of the interior of the room, in particular the sales room or the storage room, is simple and known upfront . One may typically find substantially straight aisles between rows of shelves or around presentation stands or curved areas around presentation bas kets or the like .

[0026] This insight allows a relatively slow and typically un-synchroni zed reception and processing of the radio signal , in fact the presentation ( s ) or the message , which still delivers results of suf ficient accuracy with regard to the estimation of the direction from which the radio signal was received and its further process ing in an application, for example in a navigation or routing software application .

[0027] As the width of the aisle is typically narrow, in fact in almost al l scenarios the estimated direction needs to answer a basic question, which is the question whether the radio signal was received from the left side or the right side of the grouped receiving TP0555 8 devices , so that this information can be further processed in routing or navigation applications , respectively, to guide a person or a robot within the sales room or the storage room . The fact that the di f ferent positions of the grouped receiving devices are known within the respective room ( sale room / storage room) , implies also the knowledge of a distance between the grouped devices and an orientation of an imaginary straight connecting line between them in the room . The straight connection line between two such receiving devices may be seen as the reference along which the directions left of the group and right of the group are assigned .

[0028] In fact , knowing the positions of the at least two receiving devices in the room provides the basis for the computeri zed estimating of the direction from which radio signal was received . Such knowledge is assumed to be available in computeri zed from in retail and logistics for already existing electronic equipment .

[0029] Therefore , it has proven to be advantageous that the radio signal was received within the room and that the sending device is movable within the room . The room preferably compri ses aisles . This allows a more precise estimation of the direction as described above .

[0030] The room might for example be the sales room or a storage room . A storage room might be a storage room for a sales room . The storage room can also be a standalone warehouse , e . g . a storage hall . The storage room can also be a storage hall for industry, e . g . for a manufacturing company .

[0031] Based on this the method step of computeri zed estimating the direction may make use of an upfront defined look up table , or an estimation systematics , or a functional description, or a neural network, etc . All of these measures use at least one representation of the reception signal strength of the radio signal received at one o f the receiving devices and - as the TP0555 9 case may be - a further representation of the reception signal strength o f the radio signal received at another receiving device or the message that no reception of the radio signal took place or even the lack of any further data from another receiving device of the group .

[0032] The situation that at one of the receiving devices ( the first receiving device ) a reception of the radio signal took place while at another receiving device ( the second receiving device ) no reception of the radio signal took place can easily be detected . Therefore , a timespan, for example of 1 to 5 seconds , can be defined, which defines the maximum timespan during which the second receiving device must report the reception of the radio signal , otherwise it is assumed that the second receiving device lacks reception of the radio signal . This time window is triggered by the appearance of the presentation from the first receiving device at the instance that performs the computeri zed estimation . I f otherwise the second receiving device reports the message that indicates the non-reception no particular timing needs to be taken into account . The reporting of the message takes place in accordance of the applied radio communication protocol that is used for radio communication with the receiving devices .

[0033] In summary the applicant derived the insight hat the application of dedicated high performance AoA devices leads to over-engineering for the targeted use case and a clever use of existing equipment is the means of choice to estimate the direction from which the radio signal was received .

[0034] In fact , the method steps of defining the at least two receiving devices and estimating the direction is performed in a computeri zed manner, which may be a computer that is di f ferent from the electronics of the receiving devices and the TP0555 10 electronics of the sending device . Hence , the computation intense method step of selecting or defining, respectively, the receiving devices to form the group of the at least two receiving devices together and thereafter the evaluation of the information provided by the grouped devices is kept separate from the grouped receiving devices . This clearly distingui shes the measures of the invention from known AoA detectors , which AoA detectors deliver as a result of their internal processing the direction from which the radio signal was received j ust in time of reception of the radio signal . As the computeri zed method steps discussed are preferably carried out by a computer, the subj ect matter of the invention is also a computer-implemented method for estimating a direction from which a radio signal was received, in particular within the room, preferably within a sales room or a storage room .

[0035] Furthermore , the subj ect matter of the invention is also a computer program or a computer program product compris ing instructions which, when the program is executed by a computer, cause the computer to carry out the computer implemented method according to the invention .

[0036] Furthermore , the subj ect matter of the invention is also a computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to carry out the computer implemented method according to the invention .

[0037] Further particularly advantageous embodiments and extensions of the invention arise from the dependent claims and the following description .

[0038] Regarding the representation of the reception signal strength of the received radio signal it is to mention that this representation may be given in the power unit Watt . However, according to a preferred embodiment the "Received Signal Strength Indicator" , TP0555 11 abbreviated as RSS I , may be used because in the present application of this invention it is common that the receiving circuit of the respective receiving device computes this value automatically . The RSS I represents the power level of signals received by a wireless device . It indicates the strength of the signal and is expressed in dBm ( decibels relative to one milliwatt ) , for example in the range of 0 dBm to - 120 dBm . A higher RSS I value generally corresponds to a stronger signal . As an example , an RSS I of less than - 90 dBm indicates an extremely weak signal , in particular at the edge of receivability of the signal , while an RSS I of more than -30 dBm indicates a very strong signal coming from a sending device in closest proximity .

[0039] The receiving devices may be used only for the purpose of receiving the radio signal from the sending device . Further to this , the receiving devices may be installed or positioned, respectively, at defined position within the sales room or the storage room, for example at the wall or the sealing or at columns etc . However, to achieve a maximum of ef ficiency and cost savings , it is of particular advantage that the receiving devices comprise a further functionality, which is used within the sales room or the storage room . Therefore , it is of particular advantage that as the receiving device an electronic equipment of the following group i s used :

[0040] - an electronic shel f label device ,

[0041] - an electronic video shel f rail ,

[0042] - an electronic temperature sensor,

[0043] - an electronic humidity sensor,

[0044] - an electronic balance

[0045] - an electronic tactile interaction device ,

[0046] - an electronic proximity detector device ,

[0047] - an electronic shel f rail .

[0048] Such an electronic equipment is typically positioned on / in / at furniture within the sales room TP0555 12 or storage room, for example a shel f , a refrigerator, a deep freezer, a delicatessen stand and / or a fruit or vegetable stand . The electronic shel f labels are used to display static information, for example simply product and / or price information, while the video shel f rails are used to display dynamic content , for example a promotion video that may also comprise a product and / or price information . The temperature or humidity sensors are used to collect temperature or humidity data, respectively . The tactile interaction devices may be used to receive a physical interaction from a person which touches the tactile interaction device . The proximity detector devices may be used to identi fy the presence of a person in its proximity, for example by means of a radar radio signal or an infrared light signal . The electronic shel f rail is known from the published international patent applications WO 2022 / 188955 Al and WO 2022 / 188956 Al . For the sake of clarity, it is mentioned that the list of electronic equipment is not exhaustive and also further devices with other functionalities or even combined functionalities may be comprised in this list .

[0049] Such an electronic equipment comprises electronics which is configured and / or programmed to provide the respective functionality of the electronic equipment . In particular, all such electronic equipment has in common that it comprises electronics , typically comprising a transceiver circuit with an antenna, and a control unit , for example a microcontroller or a microprocessor, that utili zes the transceiver to communicate function speci fic data and / or commands with a controller device . The control device being located outside of the respective equipment . The control device may be an access point , a further computer etc . It should also be emphasi zed that the term electronic equipment excludes access points or the like . These access points are also distributed TP0555 13 throughout the sales or storage area but are relatively far away from the areas of interest and have a low density within these areas .

[0050] In addition, for the sake of clarity, it should be mentioned that the at least two receiving devices do not necessarily have to be the same type of electronic equipment , but that di f ferent types of equipment can also be used .

[0051] Optimum synergetic ef fects are established by a double use of the electronics of the receiving device . Here the electronics of the receiving device , which electronics comprises the antenna and which electronics is also used for radio communication with the controller device , is also used for receiving the radio signal . In particular a transceiver unit and an internal signal and / or data processing unit of the receiving device is used on the one hand for the particular functionality of the respective device and on the other hand for the reception of the radio signal from the sending device and its further processing withing the receiving device .

[0052] A particular advantage is achieved when the radio signal is sent out from a mobile radio beacon device , which reali zes the sending device . Such a radio beacon device is typical ly identi fied by a unique code that is transported by the radio signal that is sent out . Knowing this unique code allows to identi fy the respective sending device amongst other sending devices by the at least two receiving devices , which allows focusing on the sent out radio signal only that was sent out only from one particular radio beacon device , i f more sending devices are present with in the reception range o f the at least two grouped receiving devices .

[0053] In this context it is of particular advantage that the radio beacon device is a Bluetooth ® Low Energy radio beacon device . It may be a stand-alone radio TP0555 14 beacon device , but in a preferred embodiment the radio beacon device is comprised in a mobile device with other functionalities , for example a cellular phone , tablet computer or a personal digital assistant or the like .

[0054] Applying Bluetooth ® allows the utili zation of well accepted standardi zed technology platform for the electronic equipment which is more and more demanded in the retail or logistics industry, while the same technology platform is also applied for the aspect of estimating the arrival direction of a radio signal . This double application of the standard goes without any need of additional electronic equipment that is only usable for the purpose of the estimation of the arrival direction . As already mentioned, only the software of the involved devices needs to be adapted in accordance with the provided information and explanations of the present invention .

[0055] A system in which the invention is applied may comprise a computer to control several aspects of operation . Adventurously the computer knows the identity and the positions of at least some of potential receiving devices , preferably of all of the potential receiving devices , in particular within the room, preferably within the sales room or storage room, and groups together the at least two receiving devices out of the known receiving devices to form a receiving unit . The computeri zed grouping together of the receiving devices secures a proper assembling of the receiving unit so that a meaningful information regarding the estimation of the direction can be achieved by receiving the radio signal .

[0056] That the computer knows the identity and the position of potential receiving devices means that it has access to data representing the identity and the position and / or to the computeri zed representation of a signal that allows the identi fication of the identity TP0555 15 and the position . The data representing the identity and the position might be stored on a computeri zed storage medium, e . g . a flash-memory-storage etc .

[0057] In particular the distances between the receiving devices that real i ze the receiving unit and / or particularities o f their positions are considered in the selection o f the at least two receiving devices . For example , a too low set distance as well as a too high set distance between the at least two receiving devices may lead to misleading results with regard to the estimation of the arrival direction .

[0058] I f the distance is set too low and the sending device enters the reception range in which the radio signal is receivable at the receiving devices , the received radio signal will be received at all of the receiving devices with more or less the same signal strength, which cannot be used for estimating the direction from which the radio signal was received . Consequently, the distance should be increased to have signi ficantly di f ferent signal strengths at the receiving devices of the receiving units , which allows an estimation of the direction from which the radio signal was received .

[0059] A proper selection of the distance may include the knowledge about the typical reception range of the radio signal sent out by the sending device . This typical reception range may be influenced or set by the radio sending power of the sending device and may be set to only a view, preferably single digit , meters by upfront definition of the transmission power of the sending device . This will lead to a proper assessment of the estimated direction because such distances are of interest in the sales room or the storage room, where shel f aisles are typically narrow in width but long . All this information that leads to a proper selection of the distance can be stored by the computer so to have the required parameters available for the TP0555 16 process of assembling the receiving unit . A proper selection of the distance may be given by the fact that for each of the involved receiving devices the signal strength of the radio signal is properly distinguishable as the sending device approaches the receiving unit or moves away from the receiving unit within the distance range of interest ( for example less than 4 to 10 meters ) for the speci fic application of this technology .

[0060] This speci fication may not apply while the sending device is located between two of the receiving devices that form the receiving unit , because in this position again both receiving devices may receive the radio signal with more or less the same signal strength . I f such a situation for the signal reception is detected and provided that during the approaching of the sending device towards the receiving unit the radio signal with proper distinguishable signal strengths was received, the actual direction towards the sending device can be estimated as being perpendicular to the straight connection line between the at least two receiving devices .

[0061] As a summary, it is to mention that the observation of the development of the received signal strength ( s ) in time can be used to validate the actual receiving situation at the receiving device ( s ) that contribute to the receiving unit or that form the receiving unit .

[0062] Regarding the computer it is to mention that it may be a single commuter, a server or a server farm or a so-called cloud service that hosts a software application which provides the functionalities of the computer for the respective application of interest . For example , in the context of a retailer or warehouse the software appl ication may be programmed to provide and manage in technical j argon a so termed "planogram" or "realogram", respectively, which stores products , TP0555 17 product positions and the position of electronic shel f labels in this planogram or realogram . The software application may further store price and / or product information of products and a logic link linking of this information to individual electronic shel f labels etc .

[0063] According to the method the computer receives from the receiving devices the available representation of the reception signal strength or from the receiving device that did not receive the radio signal , the message indicating the non-reception of the radio signal and computes the estimation of the direction from which the radio signal was received therefrom . The ef fect achieved is that the power consumption at the receiving devices is kept to an absolute minimum what is of essence for battery powered receiving devices and their battery li fetime . The receiving devices only consume power during its reception operation with the intention of receiving the radio signal and - in case of the reception of the radio signal - the internal computation of the representation of the reception signal strength and the delivery of the representation ( for example data representing the RSS I ) and - in case of the non-reception of the radio signal - the delivery of data representing the message . The further processing, which is an interpretation of the received representation ( s ) or message , is done at the computer without any power consumption restrictions and full computing power .

[0064] Regarding the computeri zed estimation of the direction, it should be noted that this essentially takes place in such a way that a representation of the signal strength, e . g . one or more RSS I values and / or the message , is used . This representation of the signal strength is preferably processed as a computeri zed quantity, for example as a numerical value ( e . g . integer, floating-point numbers , etc . ) . Based on this TP0555 18 input variable (s) , the direction from which the signal was received is computerized estimated, in particular, an estimate is computerized determined. This results in an output value. This output value can, for example, describe a direction from which the signal was received, e.g. in a very basic interpretation the direction right or left is identified. The output value can also, for example, indicate an estimated angle (or several estimated angles describing a special direction) that describes where the signal was coming from. The output value can also describe a space from the signal was received (e.g. a cone that describes the space segment within which the signal source should be located) .

[0065] The estimation, in particular the determination of the estimation, can be carried out in different ways. The estimation can be based on an analytically and / or numerically solvable formula or set of formulas. This formula or set of formulas can, for example, describe the geometric relationships.

[0066] The estimation can also be made on the basis of comparative values. These comparative values can be empirical values, for example. For example, several measurements can be taken and the RSSI values (or the occurrence of the message) can be logged in the context of the RSSI values. This makes it possible to estimate later that when certain RSSI values (or an RSSI value and a message) have been determined, the position of the sending device or the direction corresponds to that of the previous measurement with the same (or similar) measured (RSSI) values. Comparison values can be stored in this way. To estimate the direction, the comparison values are accessed by a computer and a starting value is determined from them. Interpolation between comparison values can also be carried out. Extrapolation can also be carried out on the basis of the comparison values. TP0555 19

[0067] The direction can also be estimated based on trained arti ficial intelligence or machine learning . This essentially involves using comparative values and / or known relationships (which can be formulated using formulas , for example ) . However, the interpretation is carried out using a trained model , which enables a more precise estimate than j ust interpolation . This also makes it possible to take into account influencing factors such as attenuation and reflection, which cannot be easily described mathematically in the case of complex shapes .

[0068] The methods described can also be combined . For example , a direction can be estimated using arti ficial intelligence and this can be veri fied using a mathematical equation .

[0069] In summary, it should be noted that the estimation can therefore involve a di f ferent number of input variables , which are processed, for example , using one of the methods described, so that at least one output variable is generated, whereby the output variable can in turn describe the situation in di f ferent ways . In general , it has proven advantageous to carry out a comparison of at least one representation during the estimation .

[0070] Therefore , according to an aspect of the invention the method further executed on the computer provides that the computing of the estimation of the direction is based on a comparison of the representation ( s ) of the reception signal strength ( s ) received from the receiving unit . In contrast to complex other methods of computing the angel of arrival of a radio signal this approach is super simple . In particular this approach is based on the insight of the applicant that in almost all situations in which this invention is intended to be applied, it is suf ficient to roughly estimate the direction, for which the simple comparison of the TP0555 20 representation of the reception signal strength is suf ficient .

[0071] According to one embodiment the comparison can be made between the representations from di f ferent receiving devices that are assumed to belong together because they were received within a preset time window of about 1 to 5 seconds . The following table visuali zes such a scenario for representations quoted in RSS I values for two receiving devices forming the receiving unit .

[0072] In terms of a geometrical interpretation the starting point for the angle estimation for indicating the direction from which the radios signal was received is the bisecting point of the straight connecting line between the two receiving devices . The direction of zero degrees is aligned with the straight connection line between the two receiving devices oriented from the first ( left ) receiving device to the second ( right ) receiving device . In this geometric interpretation the angle is measured from the straight connection line ( for example at the second receiving device ) along the bow in a clockwi se direction .

[0073] Table 1 : first example of a look up table . TP0555 21

[0074] Instead of point like values also RSS I value ranges may be compared to estimate angular ranges that correspond to the RSS I value ranges .

[0075] According to another embodiment , the comparison can be made between at least one of the representations and pre-defined comparison values or comparison value ranges to estimate the direction . In the following table the RSS I values of the second receiving device are compared with comparison values to estimate the direction and the representation or message from the first receiving device is used to validate i f the sending device is located either on the right side or on the left side with regard to the bisecting point of the straight connecting line between the two receiving devices .

[0076] Table 2 : second example of a look up table . TP0555 22

[0077] Alternatively or additionally to the aforesaid, the procedure can apply the following estimationsystematics :

[0078] - I f only one of the two receiving devices receives the radio signal than the receiving device that receives the radio signal is located substantially between the sending device and the other receiving device , which defines a first extreme direction . Spoken in geometric terms , the sending device is estimated to be located along a straight connection line that connects the two receiving devices , probably slightly deviation from such a connection line (because of circumstances defined by the environment ) . Speaking in geometric language this may be phrased as follows . The direction from which a radio signal was received is limited by a slender cone with a narrow opening angle of a few degrees ( for example 1 ° to 10 ° ) and whose central axis runs along the straight connecting line . The tip of the cone is located at the position of the receiving device that does not receive the radio signal of the sending device , while the base of the cone is located at the position of the other receiving device that receive the radio signal of the sending device . Alternatively, the tip of the cone may also be located at a point of the straight connection line hal fway between the two receiving devices .

[0079] - I f both receiving devices receive the radio signal with substantial ly the same signal strength than the sending device is located substantially in a plane that extends perpendicular on the straight connection line between the two receiving devices ( or normal to the straight connection line ) and cuts the straight connection line into two sections of equivalent length, which defines a second extreme direction .

[0080] - I f both receiving devices receive the radio signal with di f ferent signal strengths than the estimated direction - seen from an intersection point of the TP0555 23 straight connection line with the plane - lies between the first extreme direction and the second extreme direction, which defines a transition zone between the first extreme direction and the second extreme direction . In other words , the estimated direction - seen from the intersection point - is oriented between the mantle of a cone and the plane .

[0081] Within the transition zone the direction is estimated by scaling a remaining range of directions between the first extreme direction and the second extreme direction, in particular by using the ratio of the two signal strengths of the radio signal received by the at least two receiving devices in the scaling . With the remaining range of directions , the angular range between the mantle of the cone and the plane is meant . The scaling, for example , may be based on the comparison methods explained above . This leads to certain granularity in the results of the estimation . Therefore , alternatively a functional scaling may be considered, in which a mathematical function is established that describes the estimated direction in degrees as a function of the at least two presentations received from the at least two receiving devices . Instead of a mathematical function also a neural network etc . may be applied to estimate the direction based on two input parameters , which are the at least two presentations received from the at least two receiving devices . In both scenarios (mathematic function / neuronal network) upfront to the application the function and its parameters must be defined, and the neural network must be trained . This allows a smooth scaling of the remaining directions with suf ficient precis ion of the results , probably including an angular range of uncertainty in the estimation of the direction . The range of uncertainty can be set arbitrary but reasonable . TP0555 24

[0082] According to a further aspect it may be of advantage that the computer takes into account the obj ect or its form, respectively, at which the receiving devices are installed and / or takes into account the environment that surrounds the receiving devices . These aspects define form caused or environment caused boundary conditions . The ef fect achieved is that the estimation results , which may allow multiple interpretations , can be limited to such results that match the boundary conditions introduced by the obj ect or its form or even by the environment . Taking into account the obj ect or its form, respectively, at which the receiving devices are installed and / or taking into account the environment that surrounds the receiving devices may comprise the relative positioning of the receiving devices of the receiving unit with regard to each other and / or the geometry defined by the relative positioning, which is known to the computer as it knows the identity and the positions of all the receiving devices . For example , the obj ect at which the receiving devices are installed may be a straight shel f rail delimiting a shel f floor at its front edge . As a further example the obj ect may be a square shaped fruit and vegetable stand, or a delicatessen stand or even a circumferentially curved basket etc .

[0083] On such obj ects the receiving devices that are installed along such structures define a particular orientation of the straight connection line between two neighboring receiving devices . On straight obj ects the connection line will keep its orientation when the assembling of the reception unit is changed while on curved obj ects or obj ects having further shapes like the mentioned stands the orientation of the straight connection line between two receiving devices forming the receiving unit may change as the members of the reception unit are changing . TP0555 25

[0084] Further to this , also the environment may be considered . As an example , shel f aisle as mentioned are in fact relatively narrow when compared with their length . In such an environment it would be suf ficient to know that the sending device is somehow further away from the receiving unit either on its left side or its right side , which corresponds to the above explained first extreme situation . Moving the sending device closer to the receiving unit will lead to an estimation of the direction that is characteri zed by the transition zone . In fact , the information derived is that the sending device is now located either on the left or on the right side of the receiving unit but in proximity as be fore when only one of the receiving deceives received the radio signal from the sending device . Moving the sending device now further at a position more or less corresponding to the center point between the two receiving devices that assemble the receiving unit wi ll lead to an estimation that indicates the second extreme direction .

[0085] Given the realistic application scenario in which the sending devices is moved, it is of particular advantage that the computer re-composes the receiving unit while the sending device is moved, in particular within the room, preferably within the sales room or storage room . This means that the computer changes the particular receiving devices that form the receiving unit by selecting others out of the totality of the receiving devices . Hence the computer is configured to dynamically adapt the receiving device configuration for the receiving unit , or in other words , the computer ( figuratively speaking) "moves" the receiving unit through the interior of the sales room or storage room by changing the configuration of the receiving devices that form the receiving unit . The re-composition of the receiving unit can be archived by changing only one of the receiving devices , a plurality of the receiving TP0555 26 devices or all of the receiving devices . According to one example at least one of the already used receiving devices remains part of the new receiving unit archived by the re-composition .

[0086] In fact , a pos ition of the receiving unit as such may be characteri zed by the averaged position of the receiving device that constitute the receiving unit . Directions may be quoted for example from that position of the origin .

[0087] In this context it has proven to be of particular advantage that computer detects the movement of the sending device by analyzing the temporal change of the representation of the reception signal strength . This can be achieved by analyzing the received radio signal strength over time for only one of the receiving devices of the receiving unit . However, a better or more precise indication for the movement , in particular also a directional information of the movement , can be derived i f the temporal development of the representation of the received radio signal strength is analyzed for the at least two receiving devices . Preferred, the series of RSS I values generated over time are used to perform the movement detection . The movement is in particular detected as the RSS I values increase or decrease in time during a predefined timespan, for example 5 to 20 seconds .

[0088] This allows that the re-composing of the receiving unit takes into account a predetermined or an anticipated route of the sending device , in particular within the room, preferably within the sales room or storage room . The predetermined rout may be derived from a shipping l ist that is made available in digital from to the computer . The anticipated rout may be derived from the actual detected movement . As the movement is typically caused by a certain task to be accomplished ( for example the picking of products or the collection of materials or packages or even the re- TP0555 27 stocking of products or the delivery of materials or packages to certain storage positions ) it is of great help to re-compose the receiving unite over time to keep track of the actual movement and to assist achieving the operational target by the delivery of routing information . The routing information may be delivered to a mobile device , e . g . a cellular phone , in particular a smart phone or a personal digital assistant etc . of the person moving the sending device or to an electronic driving control of device that autonomously moves the sending device . The mobile device might be the radio beacon device or a mobile device di f ferent from the radio beacon device .

[0089] As can be derived from the preceding general description a possible configuration of the receiving unit has only two receiving devices as a minimum configuration . However, creating the receiving unit with more than two receiving devices ( for example three , four, f ive , six and so on, up to for example ten receiving devices ) may enhance the reliability of the estimated direction . Again, in the process of estimating the directing the earlier explained comparison and / or estimation systematics is preferably always applied to pairs of receiving devices of the receiving unit . The selection of pairs leads to receiving sub-units within the receiving unit , whereby the distances between tween individual receiving devices can vary from sub-unit to sub-unit and also the position of the sub-unit can change within the boundaries defined by the receiving unit . Also the orientation of the straight connection line of the subunits may change from sub-unit to sub-unite . By doing so the estimated direction can be provided with more accuracy and / or the validation of the estimated direction can better take into account the form or environment caused boundary conditions . TP0555 28

[0090] It shall be mentioned that the receiving device might comprise exactly one antenna, in particular the electronics of the receiving device might comprise exactly one antenna for receiving the radio signal .

[0091] However, it has proven to be advantageous that the receiving device comprises more than one antenna, in particular the electronics of the receiving device comprises more than one antenna . There might be 3 , 4 , 5 or even 6 antennas . These antennas are designed and used to receive the radio signal that was sent by the sending device . The electronics is configured the utili ze the antennas , for example in a time multiplex receiving process to receive the radio signal with each of the antennas and to derive for each antenna an individual RSS I values . Preferably the receiving device and / or the electronics of the receiving device comprises exactly two antennas for the purpose of estimating the direction from which the radio signal was received . Already with two antennas the quality of estimating the direction from which the radio signal was received can be signi ficantly improved when compared with a receiving device that comprises only one antenna . Advantageously this embodiment is still signi ficantly more cost-ef ficient when compared to the known application of the AoA detector .

[0092] The at least two antennas are preferably positioned at a known distance from one another within the receiving device . I f the radio signal arrives at the two antennas with di f ferent strengths , the direction of the signal can be estimated . This alone allows an approximate estimate of the direction from which the radio s ignal originates . Together with the second receiving device , the direction of the signal can be determined particularly more precisely . On the one hand, the estimated direction of the radio signal can be veri fied, and on the other hand, a second antenna within the receiving device represents another TP0555 29 spatial point that enables a geometric interpretation of the origin of the radio signal . This allows for example , to derive an analytically solvable system of equations consisting of at least three equations in order to calculate the origin of the signal . The equations describe the geometric relationship between the signal strengths determined at the antennas and the geometric conditions . With multiple antennas , e . g . two receiving devices each with two antennas or even at least two receiving devices each with two or more antennas , an overdetermined system of equations can be defined, which can compensate for inaccuracies ( e . g . due to measurement errors caused by attenuation and reflection) . Of course , when using multiple antennas , empirical values , e . g . tables , or machine learning can be used to interpret the measured values .

[0093] In analogy to the receiving device that comprises only one antenna, it shall be mentioned, that also the sending device might comprise exactly only one antenna, in particular the electronics of the sending device might comprise exactly only one antenna for receiving the radio signal .

[0094] In analogy to the above elaborated configuration of the receiving device with two or more antennas , it has also proven to be of advantageous that the sending device comprises more than one antenna . In particular the electronic of the sending device might comprise more than one antenna . There might be 3 , 4 , 5 or even 6 antennas . These antennas are designed and used at the sending device to transmit the radio signal . The electronics of the sending device is configured the utili ze the antennas , for example in a time multiplex sending process to transmit the radio signal with each of the antennas . Preferably the sending device and / or the electronics o f the sending device comprises exactly two antennas for the purpose of sending the radio signal for estimating the direction from which the TP0555 30 radio signal was received . Already with two antennas within the sending device the quality of estimating the direction from which the radio signal was received can be signi ficantly improved when compared with a sending device that comprises only one antenna . Such a sending device may be for example a cellular phone or a tablet computer or a personal digital assistant , etc . that comprises the two or more antennas .

[0095] Using two or more antennas on the side of the sending device can be used to determined or estimated the angle of departure of the radio signal , for example . The determination or estimate of the direction from which the radio signal was received can be based entirely on the estimated angle of departure . The estimated angle of departure can also be used as part of the determination or estimation of the direction from which the radio signal was received . The angle of departure can be used, for example , to veri fy the estimated direction of the direction from which the radio signal was received .

[0096] At the receiving device and / or at the sending device the plurality of antennas , preferably each of the antennas , may also be used to communicate within a Wireless Personal Area Network, in particular a Bluetooth Wireless Personal Area Network .

[0097] Besides the aspect of multiple antenna usage , a further aspect of the invention addresses the execution of the computeri zed steps of the method according to the invention . As mentioned, these steps may be executed by a computer with suf ficient processing power and memory and access to the data of the planogram or realogram . However, also the sending device may be used to execute the computeri zed steps of the method according to the invention by a software application with is executed on the processor of the sending device . Also the planogram data or realogram data are available as a whole or only as a particular extract of TP0555 31 interest . Such a sending device may have only one antenna or the discussed plurality of antennas for sending out the radio signal .

[0098] In particular, each of the sending device and the receiving devise is preferably designed and used for a Bluetooth communication .

[0099] Finally, it is to mention that electronic devices mentioned in the description of this patent application may be reali zed by the aid of well-known discreet and / or integrated electronics . Provided that interfaces are required the person skilled in the art will be able to select and des ign the appropriate interfacecircuitry to enable data and / or signal communication . Radio communication interfaces , known as transceivers , typically comprise an antenna configurational connected with well-known transceiver electronics . Programmable devices may comprise a microprocessor and some peripheral electronics . Such programmable devices may also be reali zed by the aid of a microcontroller or an application speci fic intergraded circuit (AS IC ) and the like . Execution o f software routines on such devices provides computer implemented functions that are discussed herein .

[0100] These and other aspects of the invention are obtained from the figures discussed below .

[0101] BRIEF DESCRIPTION OF THE FIGURES

[0102] The invention is explained again hereafter with reference to the attached figures and based on exemplary embodiments , which nevertheless do not limit the scope of the invention . In the di f ferent figures the same components are labelled with identical reference numbers . They show in schematic fashion in : TP0555 32

[0103] Fig . 1 a system for estimating a direction from which a radio signal sent out by a sending device was received .

[0104] Fig . 2 a movement of the sending device along a shel f aisle .

[0105] Fig . 3 geometric aspects of the estimation of the direction .

[0106] DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0107] Fig . 1 visuali zes a system 1 for estimating a direction from which a radio signal was received . The system 1 is installed in the premises of a retailer, whereby only a part of a sales room 2 with only one shel f 3 is shown in the figure 1 for the purpose of explaining the invention .

[0108] The shel f 3 has three shel f floors 4 , 5 and 6 , each is used for presenting products 7 to 15 . Installed on a front edge of each shel f floor 4 to 6 are electronic shel f labels 16 to 24 , abbreviated ESLs 16 to 24 . Each ESL 16 to 24 is located corresponding to the position of the particular product 7 to 15 to which it is logically linked . Each ESL 16 to 24 is used to display a price and / or product information for the respective product 7 to 15 . The system 1 further comprises an access point 25 that is used for radiocommunication with the ESLs 16 to 24 to supply ESL-data DI to the ESLs 16 to 24 , which ESL-data DI represent the price and / or product information or commands to be executed by the ESLs 16 to 24 . The system 1 further comprises a server 26 , which is connected to the access point 25 by a wire based local aera network and supplies the ESL-data DI to the access point 25 .

[0109] The ESLs 16 to 24 comprise an electrophoretic display which consumes energy only during its display content update . The ESLs 16 to 24 also comprise a first TP0555 33 transceiver that is configured to perform the physical radio communication with the access point 25 . The first transceiver is configured to deliver an RSS I value , which is a measure for the reception signal strength and delivered in the unit dBm . The ESLs 16 to 24 further comprise a first processor that is programmed to control the data flow and data processing within the ESLs 16 to 24 and the exchange of data with the access point 25 . Apart from the first processor it is to mention that also the first transceiver and the electrophoretic display may comprise individual further processors to perform their functions . The ESLs 7 to 24 comprise a battery to power their electronics .

[0110] The access point 25 comprises a second transceiver that is configured to perform the physical radio communication with the ESLs 16 to 24 . The access point 25 further compri ses a third transceiver that is configured to perform a wire-based communication with the server 26 . The access point 25 comprises a second processor that is programmed to control the data flow and data processing within the access point 25 and the data exchange with the ESLs 16 to 24 and the server 26 . Apart from the second processor it is to mention that also the second transceiver and the third transceiver may comprise individual further processors to perform their functions .

[0111] The server 26 comprises a third processor that is programmed to perform its basic operation system functions and to provide further functions that are defined by a software application, when executed . The software application might be reali zed as a computer program for carrying out a computer implemented invention as described in the general part of the description . The server 26 further comprises a mass data storage system that is used for example by the software application but also by the operation system . The server 26 comprises a fourth transceiver that is TP0555 34 configured to perform a wire-based communication with the access point 25 . In general , the third processor controls the data flow and data processing within the server 26 and the data exchange with the access point 25 . Apart from the third processor it is to mention that also fourth transceiver and the mass data storage system may compri se individual further processors to perform their functions .

[0112] The access point 25 and the ESLs 16 to 24 are programmed to execute a communication protocol according to the Bluetooth ® Core Speci fication Version 5 . 4 , Periodic Advertising with Response . Therefore , the ESLs 7 to 24 are available for radio communication only during speci fic times , which is termed the active-mode . During other times the ESLs 7 to 24 remain mainly dormant to achieve a maximum battery li fetime , which is termed the sleep-mode . The period of active-mode may vary for the ESLs 16 to 24 .

[0113] The server 26 executes the mentioned software application that manages a so termed realogram in which the shel f 3 and its position and orientation in the sales room 2 together with the products 7 to 15 and their positions within the shel f 3 are stored . The server also stores the identity of the ESLs 16 to 24 used on the shel f 3 . The planogram also stores for each product 7 to 15 the logic link between the respective product 7 to 15 and the respective ELS 16 to 24 that is assigned to it . By means of this link the server 26 can address the individual ESLs 16 to 24 to display the correct price and / or product information . Knowing the positions of the products 7 to 15 also enables the server 26 to de fine the position of the respective ESL 16 to 24 within the sales room 2 because also the geometry of the shel f 3 and the dimension of the shel f floors 4 top 6 are known to the server 26 .

[0114] The system 1 further comprises a sending device 27 which is configured to send out a radio signal S . In TP0555 35 particular the sending device 27 realizes a Bluetooth ® Low Energy Radio Beacon Device, which in the present example is embedded in a cellular phone (not shown) and which is freely movable within the sales room 2 by a person (not shown) .

[0115] The figure 1 further shows that the sending device

[0116] 27 is moved along the shelf 3, for example along a path

[0117] 28 from the right to the left. Following this path 28 the sending device 27 is moved along a shelf aisle between two such shelves 3 or even a series of such shelves 3. It shall be mentioned, that in this example the directions right and left are oriented as seen from a person looking from the aisle at the shelf 3 and the ESLs 16 to 24, i.e. as seen in figure 1. However, the directions might be defined differently, if desired or applicable .

[0118] The server 26 is also aware about the sending device 27 and knows a unique radio beacon identifier to uniquely identify the radio signal S sent out by the sending device 27.

[0119] To estimate the direction of the radio signal reception relative to the shelf 3 the server 26 and the ESLs 7 to 24 are programmed to execute a method according to the invention, which is explained in detail in the general description of this document. To further explain the method reference is made to figure 2, which shows only the relevant parts of the Figure 1. The figure 2 shows only the lower shelf floor 6, the sending device 27 and the path 28 along an aisle of shelfs, wherein in addition to the shelf 3 further three shelfs 3' are depicted in dashed lines.

[0120] According to the method, the server 26 (logically) groups together for example the ESL 22 and 24 to realize a receiving unit 30. The server 26 identifies the sending device 27 by making the unique radio beacon identifier of the sending device 27 available to ESLs 22 and 24, each of which now realizes a receiving TP0555 36 device . This enables the ESLs 22 and 24 to distinguish the reception of the radio signal S sent out by the sending device 27 from other signals that are receivable . A special command, which addresses the grouped ESLs 22 and 24 , received from the server 26 , which may also convey the unique radio beacon identi fier, triggers the addressed ESLs 22 and 24 to check during their active-mode i f the radio signal S is received . The speci fic command is being received and decoded at the ESLs 22 and 24 . I f the radio signal S is received the current RSS I value for this reception, which is computed by the first transceiver of the respective ESLs 22 or 24 , is send to the server 26 for further processing . I f the radio signal S is not received the ESLs 22 and 24 will not respond or send back a message to the server 26 that indicates the lack of reception of the radio signal S . The RSS I value generated by the first ESL 22 is represented by first RSS I date RSS ID1 and the RSS I value generated by the second ESL 24 is represented by second RSS I date RSS ID2 . Any return communication from the ESLs 22 and 24 back to the server takes place in accordance with the applied radio communication protocol , which in the present case is the mentioned Bluetooth ® speci fication . As long as the server 26 is interested in further reception activities regarding the reception of the radio signal S by the receiving unit 30 , this cycle of triggering the ESLs 22 and 24 and waiting for a response from the ESLs 22 and 24 is repeated .

[0121] According to this example , the signal strength for the radio signal S of the sending device 27 is set to such a level , that the radio signal S can only be received within a range of approximately 5 meters . Further to this it is assumed that the length of the shel f 3 is approximately also a view meters long, for example 4 to 8 meters . TP0555 37

[0122] Initially, the receiving unit 30 is out of reach for the reception of the radio signal S by the ESLs 22 and 24 , which is indicated with a position Pl along the path 28 . At thi s position Pl the sending device 27 is approximately 10 meters away from the shel f 3 .

[0123] As the sending device 27 commences on the path 28 closer to the receiving unit 30 , for example at a position P2 along the path 28 , the radio signal S is received by the ESL 24 but is still not receivable by the ESL 22 . In this situation the ESL 24 delivers an RSS I value of for example -120dBm by means of the second RSS I data RSS ID2 to the server 26 , while the ESL 22 does not deliver any RSS I value or delivers a message that the radio signal S is not received . The server 26 now applies the estimation systematics as explained in the general description of this speci fication and concludes that the sending device 27 must be located far away but already within the reception area on the right side of the receiving unit 30 , which is a rough estimation of the direction from which the radio s ignal S was received . According to the definition of the first extreme direction ( see the general speci fication) the direction towards the sending device 27 is defined as being within an angular range of a maximum of 10 ° measured from a straight connection line L that connects the two ESLs 22 and 24 . In the present example the straight connection line L is defined by the front edge of the shel f floor 6 where the ESLs 22 , 23 and 24 are af fixed .

[0124] As the sending device 27 further comes closer to the receiving unit 30 also the ESL 22 starts to receive the radio signal S for example at a position P3 . Starting from there on along the remainder of the path 28 towards the position P4 both ESLs 22 and 24 deliver their respective current RSS I value (by means of the first RSS I data RSS ID1 and the second RSS I data RSS ID2 ) during their individual active mode times to the server TP0555 38

[0125] 26 and the server 26 applies the estimation systematics by scaling the remaining angle range between 10 ° measured from the straight connection line L and 90 ° measured from the straight connection line L . A possible example of the scaling is explained further down in the speci fication .

[0126] When the sending device 27 reaches the position P4 it is located exactly between the two ESLs 22 and 24 with identical di stances between the sending device 27 and the respective ESL 22 and 24 . Therefore , the ESLs 22 and 24 deliver approximately the same RSS I values . According to the estimation systematics this situation will lead the server 26 to conclude that radio signal S was received from the second extreme direction ( see the general speci fication) , which means from an estimated direction of 90 ° measured from the straight connection line L or perpendicular to the straight connection line L .

[0127] A possible scaling may for example be achieved by knowing the maximum RSS I value and the minimum RSS I value that may be expected during the execution of the method . These values may be acquired by performing a reference measurement in a standardi zed environment and applying the acquired RSS I extreme (minimum / maximum) values for all installations that utili ze the invention or by performing a test measurement within the current installation so to acquire probably more accurate values .

[0128] For this example , it is assumed that the maximum RSS I value is -30dBm and the minimum RSS I value is - 120dBm . The ratio of these RSS I values (minimum value dividend by the maximum value ) is therefore a maximum value of 4 . The minimum value of this ration can only be 1 as the two RSS I values may become equal as explained in the context of the second extreme direction . The di f ference of the two ratios ( larger ratio-value minus lower ratio-value ) equals to the TP0555 39 value of 3 . Now taking into account that the remainder of direction between 10 ° and 90 ° is an angular range of 80 ° each unit of the di f ference of the two ratios of the RSS I values scales with 80 ° / 3 , which is approximately 26 ° .

[0129] However, also other scaling laws may be provided to derive an estimation of the direction between the first extreme direction and the second extreme direction . A potential approach to derive such a further scaling law is the acquisition of the RSS I values during the approach toward the receiving unit 30 and / or during the departure from the receiving unit 30 while also the angle between straight connection line L and the sending device 27 is recorded . This may be performed during a refence measurement under defined geometric and signal strength conditions . The acquired RSS I values may be fitted with an appropriate function ( for example a polynomial function) , so that as a result of the fit the direction may be estimated by the function .

[0130] Regardless of the scaling law used, it can be advantageous to speci fy the calculated direction of arrival of the radio signal S within an angular range that considers uncertainties , for example + / - 1 ° to + / - 5 ° . This considers that the basic idea of the method is , that it is an estimate . This also considers the real circumstances that the environment in which the method is applied and the measures of the method bring with them a natural uncertainty .

[0131] Further to this , it is to mention that in the present example it was assumed that the radio transmission power of the sending device 27 is below 1 mW so that the maximum RSS I value is always below 0 dBm, which secures the avoidance of a division by zero . By the aid of the Figures 1 and 2 the invention was explained by individual autonomously ESLs . However, according to a further exemplary embodiment , the TP0555 40 invention may be applied in an ESL-System that uses an electronic shel f rail which is installed at the front edge of the shel f floors 4 to 6 . Such a rail is for example known from the published international patent applications WO 2022 / 188955 Al and WO 2022 / 188956 Al . In this example the ESLs do not have a radio transceiver which can be used for receiving the radio signal S . In this example the radio transceiver that is used for the implementation of the invention, which in particular is the purpose of receiving the radio signal S , is available within the so termed rail controller (WO 2022 / 188955 Al : rail controller =

[0132] Versorgungseinrichtung 40 ; WO 2022 / 188956 Al : rail controller = Versorgungseinrichtung 4 ) which supplies and / or manages the ESLs that are installed at the rail and performs the radio communication with the access point 25 . In the context of the invention the rail controller performs as the receiving device and a minimum of two rail controllers assemble the receiving unit . As the rail controllers are typically installed at one of the side edges ( left side / right side ) of the electronic rail , the length of the electronic rail defines the minimum distance between the two receiving devices .

[0133] Even i f in the present case the invention was only discussed based on an aisle between two shelves , it should be highl ighted at this point that this method can of course also be used excellently with more complex aisle or shel f structures or baskets and the like .

[0134] Finally, each time that the estimated direction from which the radio signal S was received at the receiving unit 30 is computed by the computer 26 , this information is made available to a navigation software that is executed - according to the present example - also by the server 26 . The navigation software further processes this information to generate navigation TP0555 41 instructions for a human user or an autonomous vehicle in order to guide the user or the vehicle to accomplish a task within the sales room or the storage room .

[0135] In the following, reference is made to figure 3 that depicts the geometric aspects of the estimation of the direction from which the radio signal S was received . In contrast to Figure 2 only the ESLs of the shel f floor 6 are shown in solid lines that assemble the receiving unit 30 . The other ESL 23 is shown in broken lines . In addition, a perspective is applied to better visuali ze the three-dimensional situation . The straight connection line L connects the ESLs 22 with the other ESL 24 of the receiving unit 30 . Hal fway between the two ESLs 22 and 24 an origin 0 of a cartesian coordinate system with axis x, y and z is shown .

[0136] The y axis extends along the straight connection line L . The direction to the right DR of the receiving unit 30 extends into the room area along the y-axis to the right (positive y-axis values ) of the ESL 24 . The direction to the left DL of the receiving unit 30 extends into the room area along the y-axis to the left (negative y axis values ) of the ESL 22 . For explanatory reasons only it i s assumed that the path 28 runs in a plane defined by the x and y axes . The direction from which the radio s ignal is received is visuali zed by a vector DS that starts at the origin 0. The vector DS runs in the plane defined by the x and y axis and an angel A between the y axis and the vector DS is quoted in degrees , which is the estimated direction .

[0137] A plane E that extends perpendicular on the straight connection line L between the two receiving devices 22 and 24 ( or normal to the straight connection line L ) cuts the straight connection line L into two sections of equivalent length . The plane E coincident with the plane de fined by the x- and z-axis . TP0555 42

[0138] Even i f the path 28 may run outside of the plane defined by the x- and y-axis , the results estimated would be good enough . To provide a geometry that comes closer to the geometry depicted in Figure 3 it may be checked i f other combinations of ESLs may be used instead of the ESLs 22 and 24 . Therefore , as soon as the receiving unit 30 starts receiving the radio signal S with at least one of its receiving devices 22 or 24 , a test measurement with ESLs that are positioned at di f ferent shel f f loors 4 and 5 , for example the ESLs 20 and 17 , may be performed to check i f the receiving unit 30 should be shi fted along the shel f upwards , so to say being re-assembled for example with the ESLs 19 and 21 or even with the ESL 16 and 18 .

[0139] According to a further improvement of the method according to the invention, it may be of advantage to assemble at least one further receiving unit by receiving devices in the proximity of the current receiving unit 30 or to use a single receiving device in the proximity of the current receiving unit 30 to check i f the path 28 is located in front of the shel f 3 , which means inside the aisle depicted in the Figure 2 , where the estimation of the direction makes sense . The further receiving unit and / or the further receiving device can be logically comprised in the current receiving unit 30 or operated separately of it . I f the check is not af firmative , the current receiving unit 30 must be re-located into another, probably the next aisle running in parallel to the current aisle , to deliver a meaningful estimation of the direction .

[0140] Finally, let it be noted once again that the figures described in detail above only involve exemplary embodiments , which the expert can modi fy in a wide variety of ways without departing from the area of the invention . For the sake of completeness , let it also be stated that use of the indeterminate article TP0555 - 43 -

[0141] "a" or "an" does not mean that the respective features cannot be present multiple times .

Claims

TP0555 44CLAIMS1. A method for estimating a direction from which a radio signal (S) was received, preferably within a room, particularly preferably within a sales room (2) or a storage room, wherein the method comprises the following steps:- computerized defining at least two receiving devices (22, 24) for receiving a radio signal (S) that is being sent out from a sending device (27) , wherein the at least two receiving devices are located at different known positions, in particular within the room, in particular within the sales room (2) or storage room, and the sending device (27) is movable, and- computerized estimating the direction from which the radio signal (S) was received based on representations (RSSID1, RSSID2) of the reception signal strength delivered by each of the at least two receiving devices (22, 24) as a result of receiving the radio signal at both of the at least two receiving devices (22, 24) , or based on a representation (RSSID2) of the reception signal strength delivered by a first of the at least two receiving devices (22, 24) and either a lack of another presentation (RSSI1) from a second of the at least two receiving devices (22, 24) as a result of non-reception of the radio signal (S) or a message from the second of the at least two receiving devices (22, 24) , which message indicates the non-reception of the radioTP0555 45 signal (S) at the second of the at least two receiving devices (22, 24) .

2. The method according to claim 1, wherein as the receiving device an electronic equipment of the following group is used:- an electronic shelf label device (22, 24) ,- an electronic video shelf rail,- an electronic temperature sensor,- an electronic humidity sensor,- an electronic balance,- an electronic tactile interaction device,- an electronic proximity detector device,- an electronic shelf rail.

3. The method according to claim 1 or 2, wherein an electronics of the receiving device (22, 24) , which electronics comprises an antenna and which electronics is also used for radio communication with a controller device, is used for receiving the radio signal (S) .

4. The method according to one of the preceding claims, wherein the radio signal (S) is sent out from a mobile radio beacon device, which realizes the sending device (27) .

5. The method according to claim 4, wherein the radio beacon device is a Bluetooth Low Energy radio beacon device, in particular comprised in a mobile device, for example a cellular phone or a personal digital assistant or the like.

6. The method according to one of the preceding claims, wherein a computer (26) knows the identity and the positions of at least some of potential receiving devices (16 to 24) , preferably of allTP0555 46 the potential receiving devices (16 to 24) , in particular within the room, preferably within the sales room (2) or storage room, and groups together the at least two receiving devices (22, 24) out of the known receiving devices (16 to 24) to form a receiving unit (30) .

7. The method according to claim 6, wherein the computer (26) receives from the receiving devices (22, 24) the available representation (RDSSID1, RSSID2) of the reception signal strength or from the receiving device (22) that did not receive the radio signal (S) the message indicating the nonreception of the radio signal (S) and computes the estimation of the direction from which the radio signal (S) was received therefrom.

8. The method according to claim 7, wherein the computing of the estimation of the direction is based on a comparison of the representation ( s ) (RSSID1; RSSID2) of the reception signal strength (s) received from the receiving unit (30) .

9. The method according to claim 7 or 8, wherein the following estimation-systematics are applied:- if only one of the two receiving devices (22, 24) receives the radio signal (S) than the receiving device (24) that receives the radio signal (S) is located substantially between the sending device (27) and the other receiving device (22) , which defines a first extreme direction;- if both receiving devices (22, 24) receive the radio signal (S) with substantially the same signal strength than the sending device (27) is located substantially in a plane that extendsTP0555 47 perpendicular on a straight connection line (L) between the two receiving devices (22, 24) and cuts the connection line into two sections of equivalent length, which defines a second extreme direction;- if both receiving devices (22, 24) receive the radio signal with different signal strengths than the estimated direction lies between the first extreme direction and the second extreme direction, which defines a transition zone between the first extreme direction and the second extreme direction .

10. The method according to claim 9, wherein in the transition zone the direction is estimated by scaling a remaining range of directions between the first extreme direction and the second extreme direction, in particular by using the ratio of the two signal strengths of the radio signal received by the at least two receiving devices (22, 24) in the scaling.

11. The method according to one of the preceding claims 6 to 10, wherein the computer (26) takes into account the object or its form, respectively, at which the receiving devices (22, 24) are installed .

12. The method according to any of the proceeding claims 6 to 11, wherein the computer re-composes the receiving unit (30) while the sending device (27) is moved, in particular within the room, preferably within the sales room (2) or storage room.TP0555 4813. The method according to claim 12, wherein the computer (26) detects the movement of the sending device (27) by analyzing the temporal change of the representation (RSSID1, RSSID2) of the reception signal strength.

14. The method according to claim 12 or 13, wherein the re-composing of the receiving unit (30) takes into account a predetermined or an anticipated route of the sending device (27) , in particular within the room .

15. A first use of a sending device (27) in the method according to any of the preceding claims 1 to 14, wherein the sending device (27) comprises at least two antennas, preferably exactly two antennas, for sending the radio signals (s) .

16. A second use of a sending device (27) in the method according to any of the preceding claims 1 to 14, wherein the sending device (27) executes the steps of the method.

17. A use of a receiving device (22, 24) in the method according to any of the preceding claims 1 to 14, wherein the receiving device (22, 24) comprises at least two antennas, preferably exactly two antennas, for receiving the radio signal (S) .

18. A system (1) for estimating a direction form which a radio signal (S) was received, wherein the system (1) is configured to perform the method according to one of the preceding claims 1 to 14.

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