WO2018184096A1

WO2018184096A1 - System and method of generating observations for radio beacon travel path determination

Info

Publication number: WO2018184096A1
Application number: PCT/CA2018/050267
Authority: WO
Inventors: Seyed Nima SADRIEH
Original assignee: Fathom Systems Inc.
Priority date: 2017-04-07
Filing date: 2018-03-06
Publication date: 2018-10-11

Abstract

Generating observations usable to determine travel paths of radio beacons by : generating a weighted received signal strength set comprising multiple weighted received signal strength values for selected ones of times during a period of operation based on received signal strength values of the radio beacons received at electronic hub devices; generating other weighted received signal strength sets for other selected ones of the times and generating the observations by calculating range and direction estimations of the radio beacon relative to the electronic hub devices based on the weighted received signal strength set, the other weighted received signal strength sets and known locations and orientations of the electronic hub devices.

Description

SYSTEM AND METHOD OF GENERATING OBSERVATIONS FOR RADIO BEACON TRAVEL PATH DETERMINATION

Technical Field

[0001] The present disclosure relates to received signal strength based generation of observations for determining travel paths of radio beacon generating devices.

Background

[0002] Travel paths of electronic devices may be determined based on radio beacon signals generated by the electronic devices and received at one or multiple receivers having known locations. When deployed, the receivers are often subject to different conditions due to: lack of or number and type of obstacles in the deployment environment, varied distances between the electronic device and the receivers, and relative orientation between the electronic device and the receivers, for example. Depending on the conditions, the radio beacon signals received at the receivers may be affected to a lesser or a greater extent by: noise, interference, reflections and attenuation, for example, which affect accuracy of received signal strength data. Further, different receivers may have mechanical or operational differences that may affect accuracy of received signal strength data.

[0003] Applying data pattern approximation methods, such as smoothing, for example, to improve travel path accuracy is generally not effective because the received signal strength data has been acquired at different receivers operating under different conditions. Although data pattern approximation methods may be effective for data output from onboard sensors of electronic devices, such as Inertial Measurement Units (IMU), for example, the inconsistency of the acquisition conditions, particularly when distances between the electronic devices and the multiple receivers are highly varied, causes data pattern approximation to be ineffective for received signal strength based location. Using such methods may result in reduced travel path accuracy, significant errors and lost travel path information.

[0004] Therefore, other systems and methods of improving travel path determination for electronic devices or other radio beacon signal generating devices are sought. Summary

[0005] The methods and systems disclosed herein increase the contribution of high received signal strength values on a travel path solution while reducing the contribution of erroneous received signal strength values by considering nearby, or surrounding, received signal strength values.

[0006] In an aspect of the present disclosure there is provided a method of generating observations for a radio beacon of a radio beacon location system in a deployment environment, the method comprising: receiving, at antennas of electronic hub devices of the radio beacon location system, radio beacon signals from a radio beacon, the antennas configured to receive the radio beacon signals at multiple orientations relative to the electronic hub devices over a period of operation, radio sub-systems of the electronic hub devices in communication with the antennas generating digitized data representing received signal strength values of received radio beacon signals at the multiple orientations for the electronic hub devices;

receiving the received signal strength values at a processing device in

communication with the electronic hub devices; generating, at the processing device, weighted received signal strength sets corresponding to selected ones of times within the period of operation, ones of the weighted received signal strength sets comprising multiple weighted received signal strength values determined based on the received signal strength values at the selected ones of the times and at times near to the selected ones of the times; and generating the observations at the processing device by calculating range and direction estimations of the radio beacon relative to the electronic hub devices based on the weighted received signal strength set and known locations and orientations of the electronic hub devices; wherein the multiple weighted received signal strength values of the weighted received signal strength set are considered to have occurred at the selected one of the times.

[0007] In another aspect of the present application there is provided a radio beacon location system comprising: electronic hub devices comprising antennas configured to receive radio beacon signals from a radio beacon at multiple orientations relative to the electronic hub devices over a period of operation, radio sub-systems of the electronic hub devices in communication with the antennas generating digitized data representing received signal strength values of received radio beacon signals at the multiple orientations; and a processing device in communication with the radio subsystems of the electronic hub devices, the processing device configured to: receive the received signal strength values, generate weighted received signal strength sets corresponding to selected ones of times within the period of operation, ones of the weighted received signal strength sets comprising multiple weighted received signal strength values determined based on the received signal strength values at the selected ones of the times and at times near to the selected ones of the times, and generate the observations at the processing device by calculating range and direction estimations of the radio beacon relative to the electronic hub devices based on the weighted received signal strength set and known locations and orientations of the electronic hub devices; wherein the multiple weighted received signal strength values of the weighted received signal strength set are considered to have occurred at the selected one of the times.

[0008] In still another aspect of the present application there is provided a method of generating a weighted received signal strength set based on radio beacon signals received by electronic hub devices of a radio beacon location system in a deployment environment, the method comprising: receiving, at antennas of the electronic hub devices, radio beacon signals from a radio beacon, the antennas configured to receive the radio beacon signals at multiple orientations relative to the electronic hub devices over a period of operation, radio sub-systems of the electronic hub devices in communication with the antennas generating digitized data representing the received signal strength values of received radio beacon signals at the multiple orientations for the electronic hub devices, locations and orientations of the electronic hub devices being known; receiving the received signal strength values at a processing device in communication with the electronic hub devices; selecting, at the processing device, a filter length of a filter to refine ones of the received signal strength values, the filter length selected based on an operational characteristic of the radio beacon location system; at the processing device, for a selected time within the filter, generating the weighted received signal strength set comprising weighted received signal strength values corresponding by assigning weights to the received signal strength values across the filter length, a largest weight assigned to the received signal strength value corresponding to the selected time and smaller weights assigned to the received signal strength values corresponding to times before the selected time and times after the selected time within the filter length, a size of the smaller weights proportional to a nearness of the other times to the selected time; wherein the weighted received signal strength values of the weighted received signal strength set are considered to have occurred at the selected time.

Drawings

[0009] The following figures set forth examples in which like reference numerals denote like parts. The present disclosure is not limited to the examples illustrated in the accompanying figures.

[0010] FIG. 1 is a schematic diagram of electronic hub devices and radio beacons of a radio beacon location system according to an example.

[0011] FIG. 2 is a schematic diagram of an electronic hub device according to an example.

[0012] FIG. 3 is a schematic diagram of a radio beacon according to an example.

[0013] FIG. 4 is a flowchart depicting a method of generating observations of a radio beacon signal generating device according to an example.

[0014] FIG. 5 is a flowchart depicting a method of generating weighted received signal strength sets according to an example.

[0015] FIG. 6 is a schematic diagram depicting a filter applicable to received signal strength values.

[0016] FIGS. 7A to 7C are example graphs depicting received signal strength values over time.

[0017] FIG. 8 is an example plan view of a trade show venue including an example travel path of a trade show attendee.

[0018] FIG. 9 is an enlarged view of portion D of FIG. 8.

[0019] FIG. 10 is a schematic view of an electronic hub device of the example of

FIGS. 8 and 9 showing a scanning pattern of the antenna.

[0020] FIG. 1 1 is an example graph depicting received signal strength values of hubs 1 to 4 of FIG. 9 over a period of operation.

[0021] FIG. 12 is a flowchart depicting an example estimation method for determining observations.

[0022] FIG. 13 is a schematic diagram showing a single observation determined based on radio beacon signals received at an electronic hub device.

[0023] FIG. 14 is a schematic diagram showing a location determined based on single observations by two electronic hub devices. Detailed Description

[0024] It will be appreciated that for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the examples described herein. However, it will be understood by those of ordinary skill in the art that the examples described herein may be practiced without these specific details. Unless explicitly stated, the methods described herein are not constrained to a particular order or sequence. Additionally, some of the described methods or elements thereof may occur or be performed at the same point in time. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the examples described herein. Also, the description is not to be considered as limiting the scope of the examples described herein.

[0025] Referring to FIG. 1 , an example radio beacon location system 10 including three electronic hub devices 12 and three radio beacons 14 is shown. Tracking a radio beacon 14 includes determining successive locations 16 of the radio beacon 14 over time in order to generate a travel path 18 of the radio beacon 14. Location information determined by the radio beacon location system 10 may be used for one or more of: asset tracking, analytics to discover movement patterns for customer behavior modeling, advertising campaign success assessment and other location dependent analytics.

[0026] The radio beacon location system 10 is operable in any deployment environment including outdoors, indoors and in environments in which GNSS signal reception is weak, such as in dense urban environments, for example. The radio beacon location system 10 has particular advantages when the radio beacons 14 of the system 10 do not have GNSS location capability. Some examples of deployment environments of the radio beacon location system 10 include: office structures, retail structures, hospitals, hotels, points of interest, such as tourist attractions, for example, industrial and manufacturing structures, educational campuses, cargo handling ports and resource extraction locations, for example.

[0027] The radio beacon location system 10 of FIG. 1 is shown as an example. The radio beacon location system 10 may include any number of electronic hub devices 12 and radio beacons 14. Some deployments may include two electronic hub devices 12 and a single radio beacon 14, a few electronic hub devices 12 and tens of radio beacons 14, tens of electronic hub devices 12 and hundreds of radio beacons 14 or even larger deployments. The number of radio beacons 14 per pair of electronic hub devices 12 is not fixed and may be determined based on the deployment environment. The radio beacon location system 10 is operable with any type of radio signal, such as BLE (Bluetooth™ Low Energy), Bluetooth™, FM, AM, WiFi, Digital TV, ZigBee or 6LoWPan, for example.

[0028] Referring also to FIG. 2, the electronic hub device 12 includes a main processor system 44. The main processor system 44 controls overall operation of the electronic hub device 12. The main processor system 44 includes a

microprocessor 46, a memory 20 and a communication interface 34. An example of a main processor system 44 is a Single Board Computer (SBC) with an Operating System (OS). The communication interface 34 enables communication with a server 38 via a wireless or a wired connection. The server 38 may be a single server including a processor 48 and memory 50. Alternatively, the server 38 may be a group of servers in communication with one another.

[0029] The electronic hub device 12 further includes a GNSS antenna 22 to receive GNSS signals and a GNSS sub-system 24 in communication with the main processor system 44 and the GNSS antenna 22. The GNSS sub-system 24 generates digitized GNSS data corresponding to the GNSS signals for further processing by the main processor system 44. Examples of a GNSS sub-system 24 include: a standalone GNSS receiver capable of generating a location estimate locally, an Assisted GNSS (A-GNSS) receiver that receives assistance data from another device to provide a location estimate, a Radio Frequency (RF) Front End (FE) in association with a Software Defined Radio (SDR) receiver at the electronic hub device 12 or distributed over one or more servers.

[0030] The electronic hub device 12 is capable of determining its location using the digitized GNSS data. In environments in which the signals from the GNSS satellites are weak, the electronic hub device 12 may communicate with the server 38 to process the digitized GNSS data over time. Depending on the strength of GNSS signals received, self-location may be immediate or may take hours or days, for example. As such, the electronic hub device 12 may self-locate by determining its location locally or by communicating with the server to determine its location. The electronic hub device 12 may alternatively determine its location using another method, such as using other networking structures located nearby such as Cell-ID and WiFi, for example. Alternatively, the electronic hub device 12 may retrieve information from the memory 20 that was stored at the time the electronic hub device 12 was deployed. In general, the location of the electronic hub device 12 is known and is used to determine locations of the radio beacons 14 in the methods described herein.

[0031] Radio sub-system 26 receives radio beacon signals from the radio beacons 14 via an antenna 30 and generates digitized data representing received signal strengths of the radio beacon signals received at the electronic hub device 12 at multiple orientations. The radio sub-system 26 communicates with the main processor system 44 of the electronic hub device 12 and an antenna switch 28. The antenna switch 28 controls the antenna 30 of the electronic hub device 12. The electronic hub device 12 is also capable of transmitting the digitized data for receipt at another electronic hub device 12. In an example, the radio sub-system 26 is a standalone receiver of radio signals such as BLE, WiFi, FM, AM, Bluetooth™ and Digital TV, for example, that is capable of down-converting, demodulating and decoding information transmitted by radio beacons 14. In this example, the standalone receiver may be realized using discrete components or using minimum hardware such as SDRs (Software Defined Radios).

[0032] The antenna 30 may be a single mechanically steered directional antenna or may include multiple directional antennas, as shown in FIG. 2. When the antenna 30 includes multiple directional antennas, any number of antennas that fit within the physical limitations of the electronic hub device 12 may be included. In an example in which multiple directional antennas are included, the antenna switch 28 may be operated to select a subset of the multiple directional antennas to receive the radio beacon signals from the radio beacons 14. A single antenna or a set of antennas may be selected at a time to receive beacon signals from one direction or a set of directions, respectively. In an example, the electronic hub devices 12 include six directional antennas.

[0033] The electronic hub device 12 further includes an omni-directional antenna 40 in communication with a separate radio sub-system 42 to enable the antenna 30 and the omni-directional antenna 40 to receive radio beacon signals at the same time. According to an example, the antenna 30 receives radio beacon signals while the omni-directional antenna 40 establishes connections with new radio beacons 14. In another example, the electronic hub device 12 includes a single radio sub-system 26 and the omni-directional antenna 40 is in communication with the antenna switch 28 such that the antenna switch 28 may select the omni-directional antenna 40 between selections of different directions of antenna 30 in order to obtain information regarding radio beacon signals all around the electronic hub device 12. In another example, the antenna 30 communicates with multiple radio sub-systems associated with multiple directional antennas thereof. In still another example, the electronic hub device 12 does not include an antenna switch 28 and instead includes the number of radio subsystems in communication with the main processor system 44 matches the number of antenna orientations. One or both of radio sub-system 26 and radio sub-system 42 also functions as a transmitter to transmit radio beacon signals so that other electronic hub devices 12 may locate the electronic hub device 12.

[0034] The electronic hub device 12 is powered by a power supply 36, which communicates with the main processor system 44 via a power interface 32. In an example, the power supply 36 is one or more batteries. In another example, the power supply 36 is an electrical outlet.

[0035] The radio beacon 14 may be any type of radio beacon signal generating device capable of transmitting radio beacon signals. An example radio beacon 14 is shown in FIG. 3 and includes a radio sub-system 54 with an omni-directional antenna to transmit radio beacon signals, a power interface 56 and a power supply 52, such as one or more batteries, for example. All of the radio beacons 14 of the beacon location system 10 may be the same type of device, or alternatively, one or more of the radio beacons 14 may be a different type of device. The radio beacons 14 may be stand-alone devices or may be any type of electronic device capable of generating a radio signal including Smartphones, tablets, laptop computers, fitness trackers and other wearable devices and specialized personnel tracking systems, for example. Example stand-alone radio beacons 14 that may be used with the radio beacon location system 10 include BLE radio beacons manufactured by LSR, Estimote, BlueSense and Fathom Systems, for example, or other types of electronic devices capable of generating a radio signal.

[0036] Radio signal information obtained from the radio beacon signals received at the electronic hub devices 12 is used to determine locations of the radio beacons 14 at respective times. The radio signal information may be one or more of: received signal strength (RSS) information, time of flight (ToF), Angle of Arrival, Time difference of Arrival or any combination thereof.

[0037] Referring back to FIG. 1 , the radio beacons 14 are identified as radio beacon A, radio beacon B, and radio beacon C. As shown, radio beacon C moves between locations 16, which are determined at successive times, along travel path 18. The radio beacon location system 10 is capable of determining successive locations of the radio beacons 14 and, thus, travel paths thereof. The radio beacon location system 10 is shown by way of example. As will be understood by a person skilled in the art, any system capable of generating successive locations of a radio beacon 14 based on received signal strength information may be used.

[0038] Referring to FIG. 4, a method of generating observations for a radio beacon 14 of a radio beacon location system in a deployment environment is shown. The method includes: receiving, at 58, at antennas 30 of electronic hub devices 12 of the radio beacon location system 10, radio beacon signals from a radio beacon 14, the antennas 30 configured to receive the radio beacon signals at multiple orientations relative to the electronic hub devices 12 over a period of operation, radio subsystems 26 of the electronic hub devices 12 in communication with the antennas 30 generating digitized data representing received signal strength values of received radio beacon signals at the multiple orientations for the electronic hub devices 12 and receiving, at 60, the received signal strength values at a processing device in communication with the electronic hub devices 12. Following receipt of the received signal strength values, the method includes: generating, 62, at the processing device, weighted received signal strength sets corresponding to selected ones of times within the period of operation, ones of the weighted received signal strength sets comprising multiple weighted received signal strength values determined based on the received signal strength values at the selected ones of the times and at times near to the selected ones of the times, the multiple weighted received signal strength values of the weighted received signal strength sets considered to have occurred at the selected ones of the times. Following generation of the weighted received signal strength set, the method further includes: generating the observations, at 66, at the processing device by calculating range and direction estimations of the radio beacon 14 relative to the electronic hub devices 12 based on the weighted received signal strength set and known locations and orientations of the electronic hub devices 12. The weighted received signal strength set includes weighted received signal strength values corresponding to more than one of the electronic hub devices 12.

[0039] The method of generating observations for a radio beacon 14 of a radio beacon location system 10 in a deployment environment may be performed by executing one or more software applications that are stored as computer readable code. Alternatively, the method may be performed by dedicated hardware, such as Application Specific Integrated Circuit (ASIC) or Graphics Processing Unit (GPU), for example, or by a combination of hardware and software. As will be understood by a person skilled in the art, following generation of the received signal strength values, the received signal strength values are received at the processing device for further processing. The processing device may be one or more of: any electronic hub device 12, a master one of the electronic hub devices 12 and a server 38. In an example, parts of the method are performed at the electronic hub devices 12 and parts of the method are performed at the one or more servers 38 in communication with the electronic hub devices 12. In another example, parts of the method are performed at the electronic hub devices 12 and parts of the method are performed at a master one of the electronic hub devices 12 that is in communication with others of the electronic hub devices 12.

[0040] Referring to FIG. 5 an example method of generating the weighted received signal strength sets is shown. The method includes: selecting, 66, at the processing device, a filter length of a filter, the filter length selected based on an operational characteristic of the radio beacon location system 10, and, at 68, generating, at the processing device, the weighted received signal strength sets by assigning weights to the received signal strength values across the filter length, a largest weight assigned to the received signal strength value corresponding to the selected one and smaller weights assigned to the received signal strength values corresponding to the times near to the selected ones of the times, a size of the smaller weights proportional to a nearness of the times near to the selected ones of the times to the selected ones.

[0041] Referring to FIG. 6, an example filter includes a filter length 70 that extends from time 0 to time T. Weights are applied to the received signal strength values based on the filter. A filter shape is an inverted V generally centered at a selected time, Tseiected, so that the received signal strength at the selected time is assigned a largest weight. The electronic hub devices 12 of the radio beacon location system 10 are relatively short range receiving devices, thus, accuracy increasingly decreases as the radio beacons 14 move farther away from the electronic hub devices 12. High received signal strength values generally indicate reliable radio beacon locations because high received signal strength values are less affected by noise and interference and are indicative of a relatively small distance between the radio beacon 14 and the electronic hub device 12.

[0042] Referring still to FIG. 6, weights of the filter range between 1 at the selected time Tseiected and 0 at both a beginning and an end of the filter. In order to assign weights to the received signal strength values received at the processing device, the filter is applied to the received signal strength values of at least a portion of the period of operation. Received signal strength values at times within the filter that are farther from Tseiected are assigned smaller weights than received signal strength values at times within the filter that are nearer to Tseiected. The received signal strength values are multiplied by the weights to determine the multiple weighted received signal strength values of the weighted received signal strength set. By applying the filter, received signal strength values at or very near the selected time and high received signal strength values within the filter have increased influence over the determined observations.

[0043] The filter length is selected based on an operational characteristic of the radio beacon location system 10. Operational characteristics include: an activity level of the radio beacon 14, distance between the electronic hub devices 12 in the deployment environment, a received signal strength pattern within the period of operation, and historical information about a tracked object. In some examples, the filter length is selected without user input based on the received signal strength values.

[0044] The activity level is determined by calculating an approximate average and variation of speed of the radio beacon 14 based on a distance travelled and an elapsed time. In general, a short filter length is selected for a high activity level and a long filter length is selected for a low activity level.

[0045] The distance between the electronic hub devices 12 is known at the time of radio beacon location system deployment. In general, a short filter length is selected for a deployment in which the electronic hub devices 12 are close to one another and a long filter length is selected for a deployment in which the electronic hub devices 12 are far from one another. [0046] FIGS. 7A, 7B, and 7C show received signal strength patterns of a radio beacon 14 moving through a deployment environment over a period of operation. Three electronic hub devices 12 receive radio beacon signals from the radio beacon 14. The received signal strengths corresponding to the three different electronic hub devices 12 are identified by different line types in FIGS. 7A, 7B, and 7C. The strength of the radio beacon signals received at the different electronic hub devices 12 is related to the location of the radio beacon 14 relative thereto. In general, a peak of a received signal strength pattern indicates that the radio beacon 14 is close to an electronic hub device 12. High received signal strength values generally correlate to high confidence radio beacon observations. A received signal strength pattern with an absence of peaks generally indicates that the radio beacon 14 is relatively far from the electronic hub devices 12 in the deployment environment. An example received signal strength pattern with an absence of peaks is shown in FIG. 7B. The received signal strength patterns of FIGS. 7A and 7B include one and two peaks, respectively. In general, a short filter length is selected for a received signal strength pattern that includes many peaks and a long filter length is selected for a received signal strength pattern that includes few or no peaks. In an example, the filter length is selected to include more than one peak. In another example, the filter length is selected to include one peak.

[0047] Historical information about the tracked object includes information determined based on a tracking history of the tracked object. In general, a shorter filter length is selected for a tracked object with a tracking history indicating that the tracked object is a relatively high maneuver object and a longer filter length is selected for a tracked object with a tracking history indicating that the tracked object is a relatively low maneuver object.

[0048] The filter length may be any length less than or equal to the period of operation. According to an example, the filter length may be between approximately 10 seconds (s) and approximately 500s and a period of operation may be 500s or greater. In a pedestrian tracking example, a filter length of 30s and a period of operation of 3 hours are selected. As will be appreciated by a person skilled in the art, shorter filter lengths may be used near the beginning and end of the period of operation in order to effectively apply the filter.

[0049] For the purpose of this description, filter lengths may be categorized as short, mid-length or long, for example. In an example, a short filter length is between approximately 10s and approximately 100s, a long filter length is between approximately 300s and approximately 500s, and a mid-length filter length is between approximately 100s and approximately 300s. Example relationships between the operational characteristics and the filter lengths are shown by way of example in Table I. Table I is provided by way of example and is not intended to limit the selectable filter lengths. Filter lengths below 10s and above 500s are also possible. When performing the methods described herein, a specific filter length within the range is selected.

[0050]

Table I: Relationships between operational characteristics and filter length

[0051] In examples in which the filter length is selected without user input based on the received signal strength values of received radio beacon signals at the antennas 30 of the electronic hub devices 12, relationships between the operational characteristics and filter length are included as part of the computer readable instructions when the method of FIGS. 4 and 5 is performed. The filter length may be selected based on a single operational characteristic or based on two or more operational characteristics. When two or more operational characteristics are relied upon for filter length selection, the operational characteristics may be weighted so that one of the operational characteristics has a greater influence on the filter length selection than others. In an example in which movement of buses within a large garage is tracked, the distance between electronic hub devices 12 is medium and the activity level is limited. Therefore, a filter length above 500s is selected.

[0052] Observations may be generated for any number of selected times over the period of operation by applying the filter over different time periods. For ones of the any number of selected times, multiple weighted received signal strength sets corresponding to different antenna directions may be generated. The multiple weighted received signal strength sets may be generated at the same time or successively. According to an example, weighted received signal strength sets are generated for Tseiected at 1 second intervals. Thus, the filter is applied to partially overlapping time periods within the period of operation that are offset from one another by 1 s. In this example, weighted received signal strength sets are generated for: Tseiected = x seconds, Tseiected = x+1 seconds, Tseiected = x+2 seconds etcetera. For a filter length of 50s, 50 weighted received signal strength values are generated for Tseiected.

[0053] The observations may be generated using any received signal strength based radio beacon location method. An observation may include one or more of: an angle, a range, a location and a location uncertainty. An example method is shown in FIG. 12 in which observations are generated on a hub by hub basis and then combined to determine a location is shown. According to the method, an electronic hub device 12 and a radio beacon 14 are selected, at 80 and 82. Then, at 84, weights are assigned to the multiple antenna orientations of the electronic hub device 12 corresponding to relative values of estimated signal strength. Estimated received signal strengths and corresponding weights are combined, at 86, to determine single observations of the radio beacons 14 at the electronic hub devices 12 at which radio beacon signals for those radio beacons 14 are received. The single observations include range, which is determined by applying propagation loss models associated with the antenna orientations to the received signal strength values, and direction, which is determined by identifying orientations of the antennas of the electronic hub devices 12 corresponding to strongest ones of the received radio beacon signals and determining the direction based on relative strength thereof. Uncertainties for the single observations are determined, at 88, by combining weights of the estimated received signal strengths. When the radio beacons 14 are exhausted, at 90, and the electronic hub devices 12 are exhausted, at 92, the single observations and the corresponding uncertainties are combined, at 94, to determine locations of the radio beacons 14 and uncertainties thereof.

[0054] The relative values of estimated signal strength are determined based on the multiple weighted received signal strength values of the weighted received signal strength set. The relative values of estimated signal strength are determined on an electronic hub device by electronic hub device basis by dividing the estimated received signal strength for respective antenna orientations by a largest one of the estimated received signal strengths of all antenna orientations of the electronic hub device 12. The weights may be equal to the relative values or may be adjusted to account for other factors that may affect the estimated received signal strength. Other factors include: reliability associated with the respective antenna directions and presence of obstacles in front of the respective antenna directions, for example.

[0055] The uncertainty of the single observations may be determined by summing the weights of the estimated received signal strengths. Alternatively, the uncertainty may be equal to a single one of the weights of the estimated received signal strengths, such as a largest one of the weights, for example. The uncertainty of the single observation may be adjusted based on other factors including: an overall received signal strength pattern at the electronic hub device 12 and a magnitude of the largest received signal strength at the electronic hub device 12, for example. An overall received signal strength pattern that includes more than a single peak, is indicative of a single observation that is less reliable and therefore, an uncertainty associated therewith has a higher uncertainty. A relatively low received signal strength value is indicative of a radio beacon 14 that is relatively far from the electronic hub device 12 and a relatively high received signal strength value is indicative of a radio beacon 14 that is relatively close to the electronic hub device 12. Thus, greater uncertainty is associated with the relatively low received signal strength value than the relatively high received signal strength value.

[0056] Similarly, the uncertainty of the location may be determined by summing the weights of the estimated received signal strengths. Alternatively, the uncertainty may be equal to one of the weights of the single observations, such as a largest one of the weights, for example. Other factors, such as those listed above, may also or alternatively contribute to the uncertainty of the location.

[0057] The method of FIG. 12 is performed for radio beacons 14 belonging to a group of radio beacons 14 that meet one or more thresholds. In an example, the thresholds are: 1) radio beacon signals from the radio beacon 14 are received at more than one antenna orientation; and 2) radio beacon signals from the radio beacon 14 are received at more than one electronic hub devices 12. Radio beacons 14 that generate radio beacon signals that are received at only one of the multiple antenna orientations of one or more than one electronic hub device 12 are not considered in the example described herein because observations associated with such radio beacons 14 are determined to be unreliable. For radio beacons 14 that generate radio beacon signals received at more than one of the multiple orientations of only one electronic hub device, the single observation is the determined radio beacon location.

[0058] Operation of the method of FIG. 12 will now be described with reference to FIGS. 13 and 14. As shown a first electronic hub device 12 includes six antenna orientations. In this example, signals from a radio beacon (not shown) are received at all six antenna orientations of the first electronic hub device 12, as indicated by observations 96 of the radio beacon, which are represented by dots, as shown. At 84, weights are assigned to the different antenna orientations based on the relative values of estimated signal strength. The relative sizes of the dots in FIG. 13 indicate the relative sizes of the estimated received signal strengths at the different antenna orientations. Because the observation 96 at antenna number 3 has the largest estimated received signal strength of all of the observations, the weight assigned thereto is equal to one. It follows that all other weights assigned are less than one. At 86 and 88, the estimated received signal strengths and corresponding weights are combined to determine the single observation 98, which includes a range and direction estimation and is represented by a star, as shown. Referring also to FIG. 14, 84 and 86 are performed for the second electronic hub device 12 to determine a single observation 98 therefor. Uncertainties for the single observations 98 are determined, at 88, by combining the weights of the estimated received signal strengths for the first electronic hub device 12 and the second electronic hub device 12, respectively. Relative uncertainties of the single observations 98 are indicated by the size of the stars in FIG. 14. As indicated, there is a greater uncertainty associated with the single observation of the first electronic hub device 12. The single observations 98 and the corresponding uncertainties are then combined, at 94, to determine a location 100 and uncertainty of the radio beacon 14.

[0059] Operation of the method of generating observations for a radio beacon of a radio beacon location system in a deployment environment of FIG. 4 and the method of generating weighted received signal strength sets will now be described with reference to FIGS. 8 and 9, in which the deployment environment is a trade show venue including display booths 74. Inaccurate single shot estimation of attendee locations 76 are shown in the enlarged view of FIG. 9. In the example of FIGS. 8 and 9, the radio beacon 14 emits radio beacon signals at 5 second intervals. The radio beacon 14 may be an electronic device such as a Smartphone, for example, or may be a device coupled to an identification tag worn by the trade show attendee, for example. At 58 and 60, received signal strength values generated by the electronic hub devices 12 based on radio beacon signals received from a radio beacon of a trade show attendee are sent to the processing device. For ease of description, only received signal strength values generated by electronic hub devices 1 and 4, which include two antenna directions having scanning patterns shown in FIG. 10, are considered in this example. The received signal strength values associated with antennas 1 and 2 of electronic hub devices 1 and 4 are shown in FIG. 1 1. At 62 of FIG. 4 and 66 of FIG. 5, a filter having a filter length of 150s is selected because the activity level of the trade show attendee is determined to be medium based historical information that trade show attendees do not move very quickly. At 62 of FIG. 4 and 68 of FIG. 5, for Tseiected = 100s, the multiple weighted received signal strength values are determined as shown in Table II. At 64 of FIG. 4, observations are generated using the method of FIG. 12 or another method based on the weighted received signal strength set and the known locations and orientations of the electronic hub devices 12.

[0060]

175 -105 -105 -38 -38 0 Out of fi ter range

Table II: Determination of weighted RSS values for Tseiected

[0061] Referring back to FIG. 8, a path 72 of a trade show attendee moving through the venue to view different display booths 74 is shown. In order to generate the path 72, the filter is applied to the received signal strength values received at the processing device across the period of operation. In addition to the weighted received signal strength set for Tseiected = 100s, other weighted received signal strength sets for other values of Tseiected are generated. For example, the filter may be applied at 5 second intervals including Tseiected = 105s, as shown in FIG. 1 1 , for example. The filter may also or alternatively be applied at other times in order to generate a number of weighted received signal strength sets. The path 72 is then generated based on the observations determined using the multiple weighted received signal strength sets.

[0062] In addition to tracking movements of trade show attendees through a venue for the purpose of identifying high traffic areas, for example, the system and method described herein is usable to track persons or objects in many different environments for many different purposes. For example, locations of employees on a particular day or over the course of a week, for example, may be generated for employers. Locations of movable assets within a building, such as buses within a bus garage or beds within a hospital, for example, may be generated for the purpose of optimizing resources.

[0063] Although there are particular advantages to performing the method described herein with multiple electronic hub devices 12, it is possible to perform the method with a single electronic hub device 12.

[0064] The system and method of generating observations for a radio beacon 14 of a radio beacon location system 10 in a deployment environment described herein generates weighted received signal strength sets for selected times within a period of operation in order to improve the accuracy of travel path determination. Received signal strength values before and after the selected times are weighted to increase the impact of high received signal strengths, which are indicative of reliable radio beacon locations, on the determined travel path. [0065] In addition to improving accuracy, using a weighted received signal strength set including a large number of weighted received signal strength values instead of a few received signal strength values generates a smoother travel path. By using a greater number of values, and compensating for the time offset between the values, the impact of erroneous received signal strength values is thus reduced.

[0066] Specific examples have been shown and described herein. However, modifications and variations may occur to those skilled in the art. All such modifications and variations are believed to be within the scope and sphere of the present disclosure.

Claims

1. A method of generating observations for a radio beacon of a radio beacon location system in a deployment environment, the method comprising:

receiving, at antennas of electronic hub devices of the radio beacon location system, radio beacon signals from a radio beacon, the antennas configured to receive the radio beacon signals at multiple orientations relative to the electronic hub devices over a period of operation, radio sub-systems of the electronic hub devices in communication with the antennas generating digitized data representing received signal strength values of received radio beacon signals at the multiple orientations for the electronic hub devices;

receiving the received signal strength values at a processing device in communication with the electronic hub devices;

generating, at the processing device, weighted received signal strength sets corresponding to selected ones of times within the period of operation, ones of the weighted received signal strength sets comprising multiple weighted received signal strength values determined based on the received signal strength values at the selected ones of the times and at times near to the selected ones of the times; generating the observations at the processing device by calculating range and direction estimations of the radio beacon relative to the electronic hub devices based on the weighted received signal strength set and known locations and orientations of the electronic hub devices;

wherein the multiple weighted received signal strength values of the weighted received signal strength set are considered to have occurred at the selected one of the times.

2. The method of claim 1 , wherein generating a weighted received signal strength set comprises:

selecting, at the processing device, a filter length of a filter, the filter length selected based on an operational characteristic of the radio beacon location system, the selected ones of the times and times near to the selected ones of the times occurring within the filter;

generating, at the processing device, the weighted received signal strength sets by assigning weights to the received signal strength values across the filter length, a largest weight assigned to the received signal strength values

corresponding to the selected ones and smaller weights assigned to the received signal strength values corresponding to the times near to the selected ones of the times, a size of the smaller weights proportional to a nearness the times near to the selected ones of the times to the selected one.

3. The method of claim 1 , wherein the operational characteristic comprises at least one of: an activity level of the radio beacon, a distance between ones of the electronic hub devices in the deployment environment, a received signal strength pattern within the period of operation, and historical information about the radio beacon.

4. The method of claim 1 , wherein the filter length is selected without user input.

5. The method of claim 1 , wherein the received signal strength values across the filter length comprise two received signal strength peaks, the received signal strength peaks indicative of expected nearness of the radio beacon to at least one of the electronic hub devices.

6. The method of claim 1 , wherein the observations are generated by:

determining angles of arrival of the received radio beacon signals by identifying orientations of the antennas of the electronic hub devices corresponding to strongest ones of the received radio beacon signals, the strongest ones determined by comparing the estimated received signals strengths of the multiple orientations; and

determining ranges between the electronic hub devices and the radio beacons by applying propagation loss models associated with the antenna orientations to the received signal strength values.

7. The method of claim 1 , wherein the largest weight is equal to 1 and the smaller weights are greater than 0 and less than 1.

8. The method of claim 1 , wherein the filter length is between approximately 10 seconds and approximately 300 seconds.

9. The method of claim 1 , wherein the filter length is approximately centered on the observation time.

10. The method of claim 1 , wherein the filter length is relatively short when the activity level is high and the distance between the electronic devices is small.

1 1 . The method of claim 1 , wherein the filter length is relatively long when the activity level is low and the distance between electronic hub devices is large.

12. A non-transitory computer-readable medium having computer-readable code stored thereon, the computer-readable code executable by at least one processor to perform the method of claim 1 .

13. A radio beacon location system comprising:

electronic hub devices comprising antennas configured to receive radio beacon signals from a radio beacon at multiple orientations relative to the electronic hub devices over a period of operation, radio sub-systems of the electronic hub devices in communication with the antennas generating digitized data representing received signal strength values of received radio beacon signals at the multiple orientations;

a processing device in communication with the radio subsystems of the electronic hub devices, the processing device configured to:

receive the received signal strength values;

generate weighted received signal strength sets corresponding to selected ones of times within the period of operation, ones of the weighted received signal strength sets comprising multiple weighted received signal strength values determined based on the received signal strength values at the selected ones of the times and at times near to the selected ones of the times; and

generate the observations at the processing device by calculating range and direction estimations of the radio beacon relative to the electronic hub devices based on the weighted received signal strength set and known locations and orientations of the electronic hub devices; wherein the multiple weighted received signal strength values of the weighted received signal strength set are considered to have occurred at the selected one of the times.

14. A method of generating a weighted received signal strength set based on radio beacon signals received by electronic hub devices of a radio beacon location system in a deployment environment, the method comprising:

receiving, at antennas of the electronic hub devices, radio beacon signals from a radio beacon, the antennas configured to receive the radio beacon signals at multiple orientations relative to the electronic hub devices over a period of operation, radio sub-systems of the electronic hub devices in communication with the antennas generating digitized data representing the received signal strength values of received radio beacon signals at the multiple orientations for the electronic hub devices, locations and orientations of the electronic hub devices being known;

selecting, at the processing device, a filter length of a filter to refine ones of the received signal strength values, the filter length selected based on an operational characteristic of the radio beacon location system;

at the processing device, for a selected time within the filter, generating the weighted received signal strength set comprising weighted received signal strength values corresponding by assigning weights to the received signal strength values across the filter length, a largest weight assigned to the received signal strength value corresponding to the selected time and smaller weights assigned to the received signal strength values corresponding to times before the selected time and times after the selected time within the filter length, a size of the smaller weights proportional to a nearness of the other times to the selected time;

wherein the weighted received signal strength values of the weighted received signal strength set are considered to have occurred at the selected time.

15. The method of claim 14, wherein the operational characteristic comprises at least one of: an activity level of the radio beacon, a distance between ones of the electronic hub devices in the deployment environment, a received signal strength pattern within the period of operation, and historical information about the radio beacon.

16. The method of claim 14, wherein the filter length is selected without user input.

17. The method of claim 14, wherein the received signal strength values across the filter length comprise two received signal strength peaks, the received signal strength peaks indicative of expected nearness of the radio beacon to at least one of the electronic hub devices.

18. The method of claim 14, wherein the largest weight is equal to 1 and the smaller weights are greater than 0 and less than 1.

19. The method of claim 14, wherein the filter length is between approximately 10 seconds and approximately 300 seconds.

20. The method of claim 14, wherein the filter length is approximately centered on the observation time.