Asset tracking system

Abstract

The present invention provides an asset tracking system (100) for tracking tags (10) in a space (500), wherein the tags (10) periodically emit beacon signals (20), wherein the asset tracking system (100) includes a plurality of listener nodes (110) arranged in the space (500) and configured to detect the beacon signals (20), and wherein the asset tracking system (100) includes a control system (300), wherein the control system (300) has access to the location data of the plurality of listener nodes (110), wherein in an operating mode: each of the plurality of listener nodes (110) determines signal attributes upon detecting the beacon signal (20), wherein the listener node (110) determines a notification delay based on the signal attributes; each listener node (110) After a notification delay, the device node (110) notifies the relevant proper subset (111) of the multiple listener nodes (110) of the measurement signals (120), unless the listener node (110) has received a predetermined number n1 measurement signals (120); select one or more reporting listener nodes (112) from the multiple listener nodes (110), wherein the one or more reporting listener nodes (112) are proper subsets of the multiple listener nodes (110); the one or more reporting listener nodes (112) provide a set signal (122) to the control system (300), wherein the set signal (122) includes data related to the multiple measurement signals (120); the control system (300) determines the location of the tag (10) based on the set signal (122) and the location data.

Description

Technical Field

[0001] This invention relates to an asset tracking system. It also relates to a method for locating the transmission position of a beacon signal. Furthermore, it relates to a lighting device. Background Technology

[0002] Asset tracking systems are known in the art. For example, US10049552B1 describes an asset tracking system with multiple anchors. When a user being tracked by the system moves a tag, the tag communicates with the anchors, and data based on the communication between the tag and at least one anchor is transmitted to a server. The server determines the tag's location based on this data and detects the occurrence of an event based on that location. The server also transmits a tag alert message to each anchor, which has a tag identifier that identifies the tag and an event indicator associated with the occurrence of the event. At least one anchor transmits the tag identifier and the event indicator to the tag, which alerts the user in response to the tag alert message.

[0003] literature EP3102962A1 An asset tracking system is disclosed, in which reference nodes wirelessly measure signals received from mobile devices and report their corresponding measurement reports to a location server. Summary of the Invention

[0004] Asset tracking systems typically include three types of field devices: (mobile) tags, listener nodes (or "anchors"), and gateways. In such a system, tags can emit beacon signals, and listener nodes can detect the input beacon signals emitted by the tags and perform measurements (e.g., signal strength measurements). Measurements can typically be performed by multiple listener nodes, and these listener nodes can send these results to a gateway, from which the results can be further processed, for example, by forwarding them to a location engine on a server or in the cloud.

[0005] This system design may seem simple and straightforward. However, network traffic load (or "network load") can be linearly proportional to the product of the number of tags and the number of listener nodes. High traffic load can often be undesirable, as other traffic may also require network bandwidth.

[0006] Therefore, existing technology systems may require high-bandwidth networks.

[0007] In particular, for deployments in commercial buildings, where each gateway typically requires more than 150 nodes, this approach may be incompatible with low-data-rate networks such as ZigBee mesh or BLE mesh, which may be preferred due to their low cost, low power consumption, and ability to cover large network areas.

[0008] Therefore, one aspect of the present invention is to provide an alternative asset tracking system that preferably further eliminates at least partially one or more of the aforementioned disadvantages. The object of the present invention is to overcome or improve upon at least one disadvantage of the prior art, or to provide a useful alternative. The invention is defined by the appended independent and dependent claims.

[0009] Therefore, in a first aspect, the present invention can provide an asset tracking system for tracking tags, particularly in space. Specifically, the tags can periodically emit beacon signals. The asset tracking system may also include multiple listener nodes (also referred to as “listeners”). The multiple listener nodes can be arranged, in particular, in the space. The multiple listener nodes can be configured, in particular, to detect (or: “receive”) the beacon signals. In embodiments, the asset tracking system may include a control system, particularly wherein the control system has access to the location data of the multiple listener nodes. The asset tracking system may also have an operating mode (or “operate in operating mode”). The operating mode may include a detection phase, an announcement phase, a reporter selection phase, a reporting phase, and / or a location phase.

[0010] During the detection phase, each of the multiple listener nodes can independently determine the signal attributes (of the beacon signal) upon detecting the beacon signal; that is, each listener node exposed to the beacon signal can detect the beacon signal and independently determine its signal attributes. In an embodiment, during the detection phase, the listener node can independently determine the corresponding notification delay based on the signal attributes (determined by the listener node). The signal attributes can be derived, in particular, from the beacon signal.

[0011] During the notification phase, each listener node may notify the corresponding measurement signal, particularly the measurement signal including signal attributes, to the corresponding proper subset of multiple listener nodes after a notification delay (determined by the listener node), especially after the notification delay from the detection of the beacon signal, unless the listener node has already received a predetermined signal. In an embodiment, the predetermined signal may be a predetermined number n1 measurement signals, particularly n1 measurement signals from other listener nodes in the corresponding proper subset.

[0012] During the reporter selection phase, one or more report listener nodes can be selected from multiple listener nodes. In particular, the one or more report listener nodes can be a proper subset of the multiple listener nodes.

[0013] During the reporting phase, one or more report listener nodes may provide aggregate signals to the control system. Aggregate signals may in particular include data related to multiple measurement signals, especially multiple measurement signals received by one or more report listener nodes.

[0014] During the reporter selection phase, each listener node that has announced its measurement signals to the relevant proper subset and has received exactly a second predefined number n2 measurement signals (from the relevant proper subset) at the time of announcement is selected as one of one or more report listener nodes, in particular where n2 is selected from the range of 0-10.

[0015] During the positioning phase, the control system can determine the tag's location based on aggregated signals and location data.

[0016] The asset tracking system of this invention offers the advantage of significantly reducing traffic load. In particular, the asset tracking system of this invention reduces traffic load by performing local processing in a distributed manner within the network by the involved listeners. Even when the network includes many nodes, significant load reduction can be achieved, thereby facilitating asset tracking using low-bandwidth networks.

[0017] Therefore, the present invention can facilitate asset tracking by utilizing networks used for different primary (or secondary) functions, such as networks for lighting control. In particular, the lighting control network can preferably be based on a low-bandwidth network, such as ZigBee or Bluetooth.

[0018] In particular, the present invention can (significantly) reduce the communication load while maintaining positioning accuracy.

[0019] Therefore, in a particular embodiment, the present invention can provide an asset tracking system for tracking tags in space, wherein the tags periodically emit beacon signals, wherein the asset tracking system includes a plurality of listener nodes arranged in space and configured to detect the beacon signals, and wherein the asset tracking system includes a control system, wherein the control system has access to the location data of the plurality of listener nodes, wherein in an operating mode: each of the plurality of listener nodes determines a signal attribute upon detecting a beacon signal, wherein the listener node determines an announcement delay based on the signal attribute; each listener node announces a measurement signal to a relevant proper subset of the plurality of listener nodes after the announcement delay, unless the listener node has received a predetermined number n1 measurement signals; one or more reporting listener nodes are selected from the plurality of listener nodes, wherein the one or more reporting listener nodes are a proper subset of the listener nodes; the one or more reporting listener nodes provide an aggregate signal to the control system, wherein the aggregate signal includes data related to the plurality of measurement signals; and the control system determines the location of the tag based on the aggregate signal and the location data.

[0020] Therefore, the present invention can provide an asset tracking system for tracking tags in a space. The term "asset tracking system" can refer to any system configured to track the location and / or movement of one or more objects, particularly tags, within a space, especially a (defined) space.

[0021] The term "tag" here can refer to an object that can be tracked, especially a uniquely identifiable object, such as by providing a label for identification. Tags can be attached to (larger) objects that are expected to be tracked, such as by attaching them to an object or by being worn by a person. For example, tags can include one or more of stickers, badges, wristbands, and tokens. Furthermore, tags can be configured to emit wireless signals, such as radio beacons or, for example, Bluetooth Low Energy beacons.

[0022] The term "space" can refer to any space where it is desired to track the location of a tag. This space can, in particular, include part of a building, such as a shopping mall, factory, or hospital. However, the space can also be located externally. For example, the space can include a recreational park or farm. In embodiments, the term "space" can refer to offices, shops, warehouses, theaters, reception areas, hospitals, nursing homes, hotels, factories, airports, shopping malls, manufacturing plants, or horticultural factories. The term "space" can refer to indoor or outdoor space, especially indoor space.

[0023] The tag can periodically emit beacon signals. In one embodiment, the tag may emit beacon signals according to a regular period (e.g., every 15 minutes). However, in another embodiment, the tag may emit beacon signals according to an irregular period—e.g., a period that varies with the time of day, or whenever an external signal is received, or whenever the tag moves. For example, the tag may include a (passive) RFID tag and may emit beacon signals upon receiving (suitable) radio waves.

[0024] Beacon signals can include any type of signal that can be detected by a listener node. In an embodiment, beacon signals can include, for example, wireless communication signals, such as wireless communication signals selected from the group consisting of Bluetooth signals, ZigBee (beacon packet) signals, Wi-Fi (beacon packet) signals, ultra-wideband packet signals, and threaded signals.

[0025] In an embodiment, the beacon signal may include one or more carrier frequencies, particularly multiple carrier frequencies.

[0026] Beacon signals may include tag identification codes. These codes can be tag-specific and are particularly well-suited for uniquely identifying tags. This allows for the differentiation of different tags and the (independent) tracking of different (tagged) objects.

[0027] Beacon signals may also include beacon signal sequence numbers. These sequence numbers can be specific to a tag within a given time period and can increment sequentially until a maximum allowed number is reached, then wrap back to a minimum allowed number. This allows different beacon signals to be distinguished, and different beacon signals from a tag can be uniquely identified, for example, by a listener within a short time period, where it is known that no more than one beacon signal from a tag can have the same sequence number.

[0028] Asset tracking systems may include multiple listener nodes. In the art, listener nodes are commonly referred to as “tag listeners,” “tag locators,” “anchor nodes,” “tag scanners,” “reference nodes,” and “sniffers.” In embodiments, a listener node may be configured to detect (or: “receive”) beacon signals; that is, the listener node may be able to detect beacon signals. Listener nodes may, in particular, passively detect beacon signals. In another embodiment, a listener node may include an antenna configured to detect (or: “receive”) beacon signals.

[0029] Listener nodes can be specifically positioned in a space, specifically in the space where the tag will be tracked. Those skilled in the art will appreciate that listener nodes can be positioned in locations where tags typically cannot reach; for example, tags can be used to track people in an office building, and listener nodes can be positioned within the building's lighting system.

[0030] In this embodiment, the asset tracking system may further include a control system. The control system may be configured to control the asset tracking system, particularly multiple listener nodes.

[0031] In this embodiment, the control system may have access to location data of multiple listener nodes. The location data may specifically include data about the location of each of the multiple listener nodes in a space, such as data about the room of each listener node, or, for example, the coordinates of each listener node.

[0032] In an embodiment, the location data may further include connectivity data, which indicates the connectivity between listener nodes. Specifically, the connectivity data may indicate which listener nodes can communicate directly. Furthermore, the connectivity data may indicate the hop count between any two of the multiple listener nodes. Thus, the control system, for example, has access to information about the listener nodes from which a particular reporting listener may be reporting its data (depending on the asset tracking system settings, particularly regarding hop distance).

[0033] Asset tracking systems (especially control systems) can have operational modes. The term "mode" can also refer to "control mode." A system, apparatus, or device (see further below) can perform actions in a "mode," "operable mode," or "mode of operation." Similarly, in one method, an action, stage, or step can be performed in a "mode," "operation mode," or "mode of operation." This does not preclude the system, apparatus, or device from being adapted to provide another control mode, or multiple other control modes. Likewise, this does not preclude the possibility of performing one or more other modes before and / or after performing the current mode. However, in embodiments, a control system (see further below) may be available that is adapted to provide at least a control mode. If other modes are available, the selection of such modes can be performed, in particular, via a user interface, although other options—such as performing modes based on sensor signals or (time) schemes—may also be possible. In embodiments, an operating mode can also refer to a system, apparatus, or device that can only operate in a single operating mode (i.e., "on," without additional tunability).

[0034] The operation mode may include a detection phase, an announcement phase, a reporter selection phase, a reporting phase, and / or a location phase.

[0035] In an embodiment, during the detection phase, each of the plurality of listener nodes can (independently) determine signal attributes upon detecting a beacon signal. Thus, after the tag transmits the beacon signal, a subset of the listener nodes can detect (or: "receive") the beacon signal. Each listener node that detects the beacon signal can then (independently) determine signal attributes, where the signal attributes relate to the detection of the beacon signal, and in particular, where the signal attributes are derived from (the detection) of the beacon signal. In an embodiment, the signal attributes can be selected from the group including signal strength, signal quality, distance estimation, angle estimation, and phase estimation. Specifically, the signal attributes can be related to the distance between the tag and the (corresponding) listener nodes. For example, signal strength may weaken as the beacon signal moves away from the tag. Therefore, if a listener node detects a beacon signal with strong signal strength, the tag may be nearby, while if a listener node detects a beacon signal with weak signal strength, the tag may be far away. Similarly, signal quality may also decrease as the beacon signal moves away from the tag. The term "signal attributes" may also refer to multiple signal attributes herein.

[0036] The term "at the time of" can refer to both simultaneously and / or subsequently. Therefore, a listener node can determine signal properties simultaneously with and / or after detecting a beacon signal. For example, a listener node can determine the signal strength of a beacon signal (if detected) simultaneously with its detection, and can (directly) determine the estimated distance after detecting the beacon signal.

[0037] The term "signal strength" here can specifically refer to the power present in the detected beacon signal. In particular, signal strength can correspond to Received Signal Strength Indication (RSSI).

[0038] The term "signal quality" here can specifically refer to the quality of the detected beacon signal. Specifically, for example, quality can be determined by comparing the detected beacon signal to an (ideal) S-shaped signal. Signal quality can indicate the information content / confidence of the signal. For example, a very strong signal may generally suggest a very close proximity to the tag, but if a very strong signal has poor quality, it may indicate problems with measurement and / or interference.

[0039] In this embodiment, during the detection phase, the corresponding listener node can independently determine the notification delay based on the signal attributes (of the beacon signal). Therefore, each listener node that detects a beacon signal can evaluate the signal attributes (especially multiple signal attributes) of the detected beacon signal and can determine the notification delay accordingly. Specifically, the listener node can determine the amount of information its detection of the beacon signal relative to the tag's location based on the signal attributes. In particular, in this embodiment, the listener node believes that the greater the amount of information it detects (see below), the shorter the notification delay it chooses.

[0040] During the notification phase, each listener node may notify the (corresponding) measurement signal to a relevant proper subset of multiple listener nodes after the measurement delay, unless the listener node has already received a predetermined signal. Therefore, each listener node can essentially wait for a predetermined signal within the (self-defined) measurement delay. In the absence of a predetermined signal, after the measurement delay, the listener node then notifies the (corresponding) measurement signal to a relevant proper subset of multiple listener nodes.

[0041] The term "related proper subset" here can specifically refer to the proper subset of multiple listener nodes that a corresponding listener node is (directly) connected to, such as all listener nodes arranged within 2 hops (e.g., at a distance of 1 hop) in a network (of multiple listener nodes).

[0042] The term "proper subset" here may refer to a subset that includes at least one, but not all, elements of the corresponding superset.

[0043] The measurement signal may specifically include signal attributes. In an embodiment, the measurement signal may further include a listener node identification signal, wherein the listener node identification signal uniquely identifies the (corresponding) listener node.

[0044] In an embodiment, the predetermined signal may be one or more of a plurality of listener nodes and / or a specific signal sent by the control system.

[0045] Specifically, each listener node can announce the measurement signal after a measurement delay following the detection of the beacon signal, unless the listener node has already received a predetermined signal. Therefore, the timer for the measurement delay can start running from the moment the beacon signal is detected.

[0046] However, in another embodiment, the predetermined signal may be a predetermined number of n1 measurement signals, particularly a predetermined number of n1 measurement signals from other listener nodes (in the relevant true subset).

[0047] Therefore, each node can determine the measurement delay based on the information content of its signal attributes. For each listener node, the measurement delay can be selected such that signal attributes with higher information content result in lower measurement delays. Next, unless a predetermined number of n1 measurement signals have been received, each listener node can announce the measurement signals, especially those including signal attributes, to its relevant proper subset after the measurement delay. If a predetermined number of n1 measurement signals have been received, it means that a predetermined number of n1 other listener nodes have identified more informational signal attributes. Therefore, to reduce bandwidth usage, the corresponding listener nodes can avoid announcing measurement signals.

[0048] In another embodiment, the predetermined signal may include a notification from another listener node in the relevant proper subset, which will be the reporting listener node. This works particularly well for embodiments where n2 = n1-1 (see below).

[0049] The listener nodes that announce their measurement signals can also be referred to here as "announcing listener nodes".

[0050] During the reporter selection phase, one or more report listener nodes can be selected from a plurality of listener nodes. Specifically, in embodiments, the one or more report listener nodes can be a proper subset of the listener nodes. In embodiments, the selection of one or more report listener nodes can be based, in particular, on the order in which the listener nodes announce (correspondingly) measurement signals (see below). In another embodiment, the selection of one or more report listener nodes can be performed by a control system (see also below).

[0051] During the reporting phase, one or more report listener nodes can provide aggregate signals to the control system, specifically where the aggregate signals include data related to multiple measurement signals (received by one or more report listener nodes).

[0052] Therefore, one or more report listener nodes can aggregate the measurement signals received by the report listener nodes into a set signal, and can provide the set signal to the control system. The set signal can in particular include raw and / or unprocessed data associated with the received measurement signals. Specifically, the set signal can include tuples, where each tuple includes a listener node identification signal and (raw and / or processed) measurement signals from the (corresponding) listener node.

[0053] Therefore, the selected one or more report listener nodes can report at least a portion (especially all) of the measurement signals received by the selected one or more report listener nodes. In embodiments, the aggregate signal may also include the raw and / or processed measurement signals of the one or more report listener nodes. Specifically, each of the one or more report listener nodes can report its measurement signals, that is, each of the one or more report listener nodes can provide an aggregate signal that includes the (raw and / or processed) measurement signals of the (corresponding) report listener node and the (raw and / or processed) measurement signals of one or more other listener nodes.

[0054] The listener nodes can communicate with each other and with the control system via wireless communication protocols—specifically, via one or more of Bluetooth, ZigBee, Wi-Fi, UWB, and Thread. Therefore, in embodiments, the listener nodes (and the control system) can be configured to communicate wirelessly via one or more of Bluetooth, ZigBee, Wi-Fi, UWB, and Thread.

[0055] During the positioning phase, the control system can determine the tag's location based on aggregated signals and location data.

[0056] Specifically, the control system can determine which listener nodes the (raw and / or processed) measurement signals represent in the set of signals, and combine this with location data to determine the tag's location. In particular, the control system can determine the tag's location based on the (raw and / or processed) measurement signals (especially the (raw and / or processed) signal attributes), listener node identification signals, and location data.

[0057] In one embodiment, the signal attribute can be selected from the group consisting of signal strength (e.g., Received Signal Strength Indicator (RSSI)), signal quality, distance estimation, angle estimation, and phase estimation. In another embodiment, the signal attribute may include at least signal strength, signal quality, and / or distance estimation. The term "signal attribute" may also refer to multiple signal attributes.

[0058] The term "phase estimate" here can refer to an estimate of the phase difference between the carriers seen by the listener in the beacon signal received from the tag when the beacon signal comprises multiple carrier frequencies. The signal at each carrier frequency may result in a phase difference relative to the listener's clock frequency. The phase estimate can be the total phase difference between the minimum and maximum carrier frequencies, or the phase difference averaged or normalized to a unit number of bandwidths (e.g., 1 MHz).

[0059] In another embodiment, signal attributes may include signal strength and / or signal quality, particularly wherein the notification delay is selected to be inversely proportional to the signal attributes, especially to signal strength and / or signal quality. Therefore, the stronger the signal strength and / or signal quality, which generally means more information about the tag's location, the shorter the notification delay can be selected. In another embodiment, the notification delay may in particular be selected to be inversely proportional to the signal attributes.

[0060] In another embodiment, the signal attribute may include a distance estimate, particularly wherein the announcement delay is selected to be proportional to the signal attribute, especially to the distance estimate. Therefore, the smaller the distance estimate, i.e., the closer the tag is estimated to be to the listener node, the smaller the announcement delay can be selected.

[0061] The term "proportional" here refers to a positive correlation. In embodiments, the notification delay may be selected to be linearly dependent on signal attributes, particularly linearly dependent on multiple signal attributes. However, those skilled in the art will appreciate that the invention is not limited to the specific relationship between signal attributes and notification delay. For example, in another embodiment, the notification delay may be selected to be quadratically dependent on signal attributes.

[0062] Specifically, in one embodiment, each listener node can evaluate a predefined function, for which signal properties (especially multiple signal properties) are input parameters, and where a measurement delay is an output parameter. In another embodiment, each listener node can evaluate the same predefined function. In yet another embodiment, at least two of the multiple listener nodes can evaluate different predefined functions, particularly where the different predefined functions are assigned to the two listener nodes by the control system.

[0063] In another embodiment, the predefined function may further include one or more variables whose values ​​are controlled by the control system. Specifically, the control system may be configured to assign values ​​to one or more variables, particularly for a particular listener node. Thus, in an embodiment, at least two of a plurality of listener nodes may evaluate the same predefined function, but with different values ​​for one or more variables. Consequently, the control system may, for example, preferentially select one or more listener nodes, e.g., because one or more listener nodes have previously proven to be particularly informative and / or accurate.

[0064] Typically, in an embodiment, the predefined function can be the same for multiple listener nodes; that is, the different output values ​​of different listener nodes can simply be functions of the differences in signal properties (values).

[0065] One or more report listener nodes (also referred to as "report nodes") can be selected from the announcement listener nodes. Therefore, the reporter selection phase may include selecting one or more report listener nodes from the listener nodes that announced the (corresponding) measurement signal during the announcement phase.

[0066] As described, in the operating mode, particularly during the reporter selection phase, each listener node that has reported its measurement signals to the relevant proper subset and has received exactly a second predefined number n2 measurement signals (from the relevant proper subset) is selected as one of one or more report listener nodes, specifically where n2 is selected from the range 0-10. Therefore, in such an embodiment, each listener node can select itself as a report listener node when reporting its measurement signals based on the number of measurement signals it has received from other listener nodes. Such an embodiment can be particularly advantageous because the report listener nodes can be dynamically selected by the listener nodes in a self-organizing manner. Therefore, communication (at least partially) with the control system can be avoided for selecting one or more report listener nodes.

[0067] In another embodiment, n2 can be 0. Therefore, a listener node can be selected as a reporting listener node when it is the first listener node in the (corresponding) proper subset of the (corresponding) measurement signal that has been announced. Specifically, a listener node can be selected as a reporting listener node when it announces the (corresponding) measurement signal before another listener node in the (corresponding) appropriate sensing subset announces its measurement signal.

[0068] In another embodiment, n2 can be n1-1. Therefore, a listener node can be selected as a reporting listener node when it is the last listener node in the (corresponding) relevant proper subset of the (corresponding) measurement signals it reports. Specifically, a listener node can be selected as a reporting listener node when it reports (corresponding) measurement signals after receiving n1-1 measurement signals from other listener nodes in the (corresponding) appropriate sensing subset.

[0069] In this embodiment, n2 can be at least one number selected from the range 0-10. Therefore, each listener node can include a second predefined number n2 that defines at least one integer in the range 0-10. For example, the second predefined number n2 could include the numbers 0 and n1-1. This could mean that both the first and last notification nodes could be selected as reporting nodes.

[0070] In one embodiment, the control system may set a second predefined number n2 for each of the listener nodes (e.g., each of a plurality of listener nodes).

[0071] In this embodiment, each of the multiple listener nodes can randomly select a second predefined number n2 value from the range of 0-10.

[0072] In an embodiment, a listener node selected as a report listener node, particularly when selecting itself as a report listener node, can announce to the relevant proper subset that it will be a report listener node.

[0073] However, one or more reporting listeners can also be selected by the control system, particularly based on the location of the listener nodes, previous measurement signals of the listener nodes, and one or more of the relevant proper subsets of the listener nodes. For example, in an embodiment, the plurality of listener nodes may include one or more central listener nodes, which may have a particularly large relevant proper subset due to their central location in the listener node network. In such an embodiment, the control system may select at least a portion of one or more central listener nodes as at least a portion of one or more reporting listener nodes.

[0074] In addition, the control system can also bias the selection of one or more report listener nodes. That is, instead of directly selecting one or more report listener nodes, the control system can choose the selection criteria of one or more report listener nodes that bias the selection of one or more report listeners, for example by setting variable values ​​in a predefined formula (see above).

[0075] Therefore, in embodiments, in the operating mode, particularly in the reporter selection phase, the control system can select one or more report listener nodes based on location data. In another embodiment, the one or more report listener nodes may include at least a first report listener node and a second report listener node, wherein the first report listener node has a first relevant proper subset, and wherein the second report listener node has a second relevant proper subset, and wherein the first and second relevant proper subsets overlap by at most 50% (relative to the number of listener nodes; specifically: the number of listener nodes in the two subsets relative to the total number of listener nodes in the two subsets), for example, at most 40%, particularly at most 30%, for example, at most 20%, particularly at most 10%.

[0076] In such an embodiment, the reporting listener node can wait for a predetermined amount of time before emitting the aggregation signal, specifically the predetermined amount of time between receiving the first measurement signal and emitting the aggregation signal. Thus, the aggregation signal can be correlated with the measurement signals of listener nodes whose measurement delay is below a predefined threshold.

[0077] Therefore, in such an embodiment, the predefined signal used for the listener node can be a predetermined amount of time that has elapsed.

[0078] In an embodiment, the (corresponding) proper subset of each listener node may include all (other) listener nodes among a plurality of listener nodes reachable from listener nodes in n hops, where n is selected from the range of 1-4, particularly the range of 1-3, for example the range of 1-2. Thus, each listener node may have its own proper subset of relevant data.

[0079] Asset tracking systems can be integrated into other (pre-existing) infrastructure. Specifically, in embodiments, a listener node can be integrated into a lighting device. The lighting device can be equipped with a low-bandwidth wireless communication device for controlling the lighting device. For example, a light-generating device can include or be functionally coupled to the wireless communication device, allowing the light-generating device to be remotely controlled. Therefore, in embodiments, the wireless communication device can include a listener node.

[0080] The term “lighting equipment” here may refer, for example, to one or more light-generating devices, light-controlling elements (such as lamp switches), and (occupancy) sensors.

[0081] In another embodiment, the asset tracking system may include multiple lighting devices, with at least a portion of multiple listener nodes integrated within the lighting devices.

[0082] Typically, in embodiments, the tag can periodically and independently transmit beacon signals; that is, the tag can be configured to transmit beacon signals at regular (or irregular) intervals.

[0083] However, in one embodiment, the control system can be configured (with signal generating elements) to emit a tracking signal, wherein the tag emits a beacon signal upon detecting the tracking signal. In such an embodiment, the control system can be enabled to locate the tag at any time, which can be advantageous if the tag's location may need to be determined within a short period of time, such as quickly locating a specialist in a hospital or factory.

[0084] In another embodiment, the tag may include an RFID tag, particularly a passive RFID tag, wherein the tracking signal includes an electromagnetic interrogation pulse selected to trigger the RFID tag, causing the RFID tag to emit a beacon signal.

[0085] In one embodiment, the plurality of listener nodes may include l0 listener nodes, particularly where l0 ≥ 10. In another embodiment, the relevant proper subset (in particular, each relevant proper subset) includes l1 listener nodes. Therefore, a listener node whose relevant proper subset includes l1 listener nodes can announce (correspondingly) measurement signals to l1 other listener nodes. In another embodiment, l1 may be selected independently for each relevant proper subset.

[0086] In another embodiment, l1 ≥ 1, for example, l1 ≥ 2, especially l1 ≥ 3. In another embodiment, l1 / l0 ≤ 0.75, for example, l1 / l0 ≤ 0.5, especially l1 / l0 ≤ 0.4, for example, l1 / l0 ≤ 0.3, especially l1 / l0 ≤ 0.2, for example, l1 / l0 ≤ 0.1. Therefore, the relevant proper subset of a listener node (especially the relevant proper subset of each listener node) may include at least one other listener node, for example, at least three other listener nodes. Furthermore, in embodiments, the relevant proper subset may include at most three-quarters of a plurality of listener nodes, for example, at most half of a plurality of listener nodes.

[0087] In another embodiment, one or more report listener nodes may include l2 listener nodes. Therefore, l2 listener nodes can be selected as report listener nodes. In another embodiment, l2 ≥ 1, for example, ≥ 2. In another embodiment, l2 ≤ 10, for example, ≤ 6. In particular, in another embodiment, l2 / l0 ≤ 0.4, for example, l2 / l0 ≤ 0.2, especially l2 / l0 ≤ 0.1, for example, l2 / l0 ≤ 0.05. Therefore, only a relatively small proportion of the listener nodes can be selected as one or more report listener nodes, which can advantageously reduce the amount of data communication toward the control system.

[0088] In another embodiment, the notifying listener nodes (i.e., the listener nodes that notify their measurement data) may include l3 listener nodes. In another embodiment, l3 / l0 ≤ 0.75, for example, l3 / l0 ≤ 0.5, especially l3 / l0 ≤ 0.4, for example, l3 / l0 ≤ 0.3, especially l3 / l0 ≤ 0.2, for example, l3 / l0 ≤ 0.1. In another embodiment, l2 / l3 ≤ 0.4, for example, l2 / l3 ≤ 0.2, especially l2 / l3 ≤ 0.1, for example, l2 / l3 ≤ 0.05.

[0089] In this embodiment, at least a portion of the plurality of listener nodes may be included in a mesh network. Therefore, in this embodiment, the plurality of listener nodes may be connected via a mesh network.

[0090] The tracking of tags can depend in part on the density of listener nodes in the space where the tags are tracked. Therefore, in an embodiment, the listener nodes can be arranged in a grid, wherein each listener node is arranged at a distance of up to 50 meters, for example up to 20 meters, especially up to 10 meters, for example up to 5 meters from the nearest other listener node among a plurality of listener nodes.

[0091] Phrases such as “In operating mode, the control system may select one or more report listeners,” or “In operating mode, the control system selects one or more report listeners,” or “In operating mode, the control system performs a method (steps),” or “In operating mode, the control system may perform a method,” and similar phrases, in the embodiments, may also be understood as the control system being configured to perform the indicated action (in operating mode), such as being configured to select one or more report listeners in operating mode, or being configured to perform a method (steps) in operating mode.

[0092] In another aspect, the present invention provides a method for locating the (transmission) position of a (tag's) beacon signal in space, wherein a plurality of listener nodes are arranged in the space, and particularly wherein the listener nodes are configured to detect the beacon signal. Furthermore, the position data of the plurality of listener nodes may be available. The method may include a detection phase, an announcement phase, a reporter selection phase, a reporting phase, and / or a location phase.

[0093] The phrase "method for locating beacon signals" and similar phrases in the embodiments may also be interpreted as a method for locating tags (that emit beacon signals).

[0094] This method, particularly the detection phase, may include detecting beacon signals using a subset of the detection data from listener nodes. In an embodiment, each listener node in the detection subset may: determine the signal properties of the beacon signal; and determine a notification delay based on the signal properties.

[0095] The method, particularly the notification phase, may further include, after a notification delay, each listener node in the detection subset notifying a related proper subset of multiple listener nodes of a measurement signal, particularly a measurement signal including signal attributes, unless the listener node has already received a predetermined signal, particularly a predetermined number of measurement signals.

[0096] This method, particularly the reporter selection phase, may include selecting one or more report listener nodes from a plurality of listener nodes, especially where one or more report listener nodes are a proper subset of the listener nodes.

[0097] The method, particularly the reporting phase, may include providing a set of signals from one or more report listener nodes, especially where the set of signals includes data related to multiple measurement signals (received by one or more report listener nodes).

[0098] This method, especially the localization phase, may include determining the (emission) location based on aggregated signals and location data from multiple listener nodes.

[0099] Therefore, in a particular embodiment, multiple listener nodes can be arranged in space, wherein the listener nodes are configured to detect beacon signals, and wherein the method includes: detecting the beacon signals with a detection subset of the listener nodes; wherein each listener node in the detection subset: (i) determines the signal properties of the beacon signal; (ii) determines a notification delay based on the signal properties; and (iii) notifies a measurement signal to a relevant proper subset of the multiple listener nodes after the notification delay, unless the listener node has received a predetermined number of measurement signals; selecting one or more reporting listener nodes from the multiple listener nodes, wherein the one or more reporting listener nodes are a proper subset of the listener nodes; providing an aggregate signal from the one or more reporting listener nodes, wherein the aggregate signal includes data related to the multiple measurement signals; and determining a (transmission) location based on the aggregate signal and location data of the multiple listener nodes.

[0100] In embodiments, signal attributes may include signal strength or signal quality, and notification delay may be (selected) inversely proportional to the signal attributes, particularly inversely proportional to signal strength and / or particularly inversely proportional to signal quality. In embodiments, notification delay may in particular be (selected) inversely proportional to the signal attributes.

[0101] In another embodiment, the signal attributes may include a distance estimate, and the notification delay may (be selected) be proportional to the signal attributes, particularly proportional to the distance estimate.

[0102] In one embodiment, at least some of the listener nodes may be integrated into a lighting device. The lighting device may, in particular, be arranged to illuminate at least a portion of the space.

[0103] In an embodiment, the method may include selecting reporting listener nodes based on the measurement delay of listener nodes in a detection subset, wherein each listener node in the detection subset is reported as a listener when it reports that its measurement signals have been received from the relevant proper subset exactly a predefined number n2 measurement signals, particularly where n2 is selected from the range 0-10, more particularly where n2=0, or more particularly where n2=n1-1. In all aspects, the second predefined number n2 may also be at least one number selected from the range 0-10, for example, n2=0 and / or n2=n1-1.

[0104] In another embodiment, the method may include selecting one or more report listener nodes based on location data. In yet another embodiment, the one or more report listener nodes may include at least a first report listener node and a second report listener node, wherein the first report listener node has a first relevant proper subset, and wherein the second report listener node has a second relevant proper subset, and wherein the first and second relevant proper subsets overlap by at most 50% (relative to the included listener nodes), such as at most 40%, particularly at most 30%, such as at most 20%, particularly at most 10%.

[0105] On the other hand, the present invention can provide a lighting device that includes at least one listener node as defined herein, for use in an asset tracking system as defined herein. In a particular embodiment, such a lighting device can be used for the method described above for locating the (transmission) position of a (tag's) beacon signal in space.

[0106] In embodiments, the lighting device may include a light generating device, a light control element, or a (proximity) sensor, particularly a light generating device, and more particularly a illuminator.

[0107] The lighting equipment may be a part of, or may be applied to, for example, office lighting systems, home application systems, shop lighting systems, family lighting systems, accent lighting systems, spotlight lighting systems, theater lighting systems, fiber optic application systems, projection systems, self-emissive display systems, pixelated display systems, segmented display systems, warning sign systems, medical lighting application systems, directional sign systems, decorative lighting systems, portable systems, motor vehicle applications, (outdoor) road lighting systems, urban lighting systems, greenhouse lighting systems, horticultural lighting, etc.

[0108] In certain embodiments, the light source includes a solid-state LED light source (e.g., an LED or a laser diode).

[0109] The term "light source" can also refer to multiple light sources, such as 2-20 (solid-state) LED light sources. Therefore, the term LED can also refer to multiple LEDs. Attached Figure Description

[0110] Embodiments of the invention will now be described by way of example only, with reference to the accompanying schematic drawings, in which corresponding reference numerals indicate corresponding parts, and in the drawings:

[0111] Figure 1 An embodiment of an asset tracking system is illustrated schematically;

[0112] Figure 2 An embodiment of an asset tracking system is illustrated schematically;

[0113] Figure 3 An embodiment of an asset tracking system is illustrated schematically.

[0114] The schematic diagrams are not necessarily to scale. Detailed Implementation

[0115] Figure 1 An embodiment of an asset tracking system 100 for tracking tag 10 in space 500 is schematically depicted, particularly wherein tag 10 periodically transmits beacon signals 20. In the depicted embodiment, the asset tracking system 100 includes a plurality of listener nodes 110 arranged in space 500 and configured to detect beacon signals 20, and a control system 300, wherein the control system 300 has access to the location data of the plurality of listener nodes 110. In the embodiment, the asset tracking system has an operating mode including one or more of a detection phase, an announcement phase, a reporter selection phase, a reporting phase, and a location phase.

[0116] In an embodiment, during the detection phase, each of the plurality of listener nodes 110 determines signal attributes upon detecting the beacon signal 20, specifically determining a notification delay based on the signal attributes. In particular, a detection subset 115 of the listener nodes 110 detects the beacon signal 20. Each listener node 110 in the detection subset determines (related) signal attributes, specifically determining (corresponding) notification delays based on the signal attributes. In the depicted embodiment, the detection subset 115 includes four listener nodes 110, comprising listener nodes 110b, 110c, 110d, and 110e, but excluding listener node 110a.

[0117] In the embodiment, during the notification phase, each listener node 110 notifies the relevant proper subset 111 of multiple listener nodes 110 (see [link to relevant documentation]) after a notification delay. Figure 2 The listener node 110 will announce measurement signals 120 unless it has already received a predetermined number n1 measurement signals 120. Specifically, a subset of listener nodes announces (corresponding) measurement signals. In the depicted embodiment, for each of the four listener nodes 110 in the detection subset 115, the other listener nodes 110 in the detection subset 115 may be part of a (corresponding) relevant proper subset. Furthermore, in the depicted embodiment, n1 may be equal to three for each listener node 110. Therefore, at most three listener nodes 110 in the detection subset 115 will announce measurement signals. Specifically, in the depicted embodiment, listener nodes 110b and 110c announce measurement signals 120, while listener node 120d does not announce. Therefore, the signal attributes determined by listener nodes 110b, 110c, and 110e may provide more information about the location of tag 10 than the signal attributes determined by listener node 110d, because listener nodes 110b, 110c, and 110e determine a smaller measurement delay based on the (corresponding) signal attributes compared to listener node 110d.

[0118] In an embodiment, during the reporter selection phase, one or more report listener nodes 112 are selected from a plurality of listener nodes 110, particularly from a detection subset 115, and even more particularly from a notification subset, wherein the one or more report listener nodes 112 are a proper subset of the plurality of listener nodes 110. In the depicted embodiment, a single report listener node 112 is selected: listener node 110c.

[0119] In an embodiment, during the reporting phase, one or more reporting listener nodes 112 (here, listener node 110c) provide a collection signal 122 to the control system 300, wherein the collection signal 122 includes data related to a plurality of measurement signals 120. In the depicted embodiment, the collection signal 122 may include data related to the measurement signals 120 of listener nodes 110b, 110c, and 110e, particularly data related to the measurement signals 120 of each listener node 110b, 110c, and 110e.

[0120] In one embodiment, during the positioning phase, the control system 300 can determine the position of the tag 10 based on the aggregate signal 122 and the position data.

[0121] In another embodiment, the control system may further consider which listener nodes are not reporting signal attributes in order to determine the tag's location. Specifically, the tag is unlikely to be near a listener node that is not reporting measurement signals.

[0122] In the operating mode, each listener node 110 that has received exactly a second predefined number n2 measurement signals from the relevant proper subset 111, which has reported its measurement signal 120 to the relevant proper subset 111, is selected as one of one or more reporting listener nodes 112, where n2 is selected from the range 0-10.

[0123] In an embodiment, in the operating mode, each listener node that has received exactly a second predefined number n2 measurement signals from the relevant proper subset, and which has notified the relevant proper subset of its measurement signals, is selected as one of one or more reporting listener nodes 112, where n2 can be at least one number selected from the range of 0-10.

[0124] In another embodiment, in an operating mode, the control system 300 may specifically (at least in part) select one or more report listener nodes 112 based on location data.

[0125] In the depicted embodiment, the asset tracking system 100 (in particular the control system 300) can be configured to (periodically) transmit a tracking signal 30, wherein the tag 10 transmits a beacon signal 20 when the tracking signal 30 is detected.

[0126] Figure 1 An embodiment of a method for locating the position 15 of a beacon signal 20 in space 500 is also schematically depicted, wherein a plurality of listener nodes 110 are arranged in space 500, and wherein the listener nodes 110 are configured to detect the beacon signal 20. The method may in particular include a detection phase, an announcement phase, a reporter selection phase, a reporting phase, and a location phase.

[0127] In an embodiment, the method, particularly in the detection phase, may include detecting the beacon signal 20 with a detection subset 115 of the listener nodes 110; wherein each listener node 110 in the detection subset 115: (i) determines the signal properties of the beacon signal 20; and (ii) determines a notification delay based on the signal properties.

[0128] In an embodiment, the method, particularly in the notification phase, may include, after a notification delay, notifying a subset 111 of the relevant true subsets 111 of the plurality of listener nodes 110 of the measurement signal 120 of each listener node 110 in the detection subset 115 of the plurality of listener nodes 110 of the measurement signal 120 of each listener node 110 in the detection subset 115 of the measurement signal 120 of each listener node 110 of the plurality of listener nodes 110 of the measurement signal 120 of each listener node 110 in the detection subset 115 of the measurement signal 120 of each listener node 110 of the plurality of listener nodes 110 of the measurement signal 120 of each listener node 110 of ... the measurement

[0129] In an embodiment, the method, particularly in the reporter selection phase, may include selecting one or more report listener nodes 112 from a plurality of listener nodes 110, wherein one or more report listener nodes 112 are a proper subset of the listener nodes 110.

[0130] In an embodiment, the method, particularly in the reporting phase, may include providing a collection signal 122 from one or more report listener nodes 112, wherein the collection signal 122 includes data associated with a plurality of measurement signals 120.

[0131] In an embodiment, the method, particularly in the positioning phase, may include determining position 15 based on the set signal 122 and position data of multiple listener nodes 110.

[0132] In the depicted embodiment, (at least part) of the listener node 110 is integrated into the lighting device 1000.

[0133] In an embodiment, the method may include selecting a reporting listener node 112 based on the measurement delay of listener nodes 110 in the detection subset 115, wherein each listener node 110 in the detection subset 115 is reported as a reporting listener 112 when a listener node 110 reports that its measurement signal 120 has been received from the relevant proper subset 115 exactly a predefined number n2 measurement signals 120, where n2 is selected from the range 0-10. Thus, for example, with respect to the depicted embodiment, n2 may be 0, meaning that listener node 110c is the first listener node 110 to report measurement signal 120. Similarly, n2 may be equal to n1-1, meaning that listener node 110c is the last listener node 110 to report measurement signal 120. In various aspects, n2 may be at least one number selected from the range 0-10. For example, n2 may be 0 and / or 10.

[0134] In one embodiment, n2 can be independently selected from the range of 0-10 for each listener node. In another embodiment, n2 can be the same for each listener node.

[0135] In one embodiment, the control system may set a second predefined number n2 for each of the listener nodes (e.g., each of a plurality of listener nodes).

[0136] In another embodiment, the method may include selecting one or more reporting listener nodes 112 based on location data and / or previous measurement signals 120 from a plurality of listener nodes 112.

[0137] Figure 2 An embodiment of an asset tracking system 100 is schematically depicted, wherein at least a portion of a plurality of listener nodes 110 is included in a mesh network 200. In particular, each node in the mesh network 200 may represent a lighting device 1000 that includes a listener node 110. Thus, in the depicted embodiment, (at least partially) the listener nodes 110 are integrated into the lighting device 1000.

[0138] In the mesh network 200, each edge between two nodes indicates that the corresponding nodes can communicate directly, meaning the connected nodes are arranged with a hop distance of 1. Therefore, for a hop distance of 1, the relevant proper subset 111 of listener node 110h includes all other listener nodes 110 within the one-hop relevant proper subset 111h1, which consists of three listener nodes 110. Similarly, for a hop distance of 2, the relevant proper subset 111 of listener node 110h includes all other listener nodes 110 within the two-hop relevant proper subset 111h2, which consists of five other listener nodes 110.

[0139] Therefore, in the embodiment, the relevant proper subset 111 of each listener node 110 includes all of the multiple listener nodes 110 that can be reached from the listener node 110 in n hops, where n is selected from the range of 1-4, for example, the range of 1-2, especially where n=1, or especially where n=2.

[0140] Figure 3 Another embodiment of the asset tracking system 100 is schematically depicted, wherein a listener node 110 is integrated into a lighting device 1000. Specifically, Figure 3 A lighting device 1000 is schematically depicted, comprising light-generating devices such as lamps 1001 and illuminators 1002, and a lighting control element 1003 such as a user interface (e.g., a graphical user interface). Reference numeral 1010 indicates light generated by the lighting device 1000. Specifically, this light is visible light, such as white light. The lighting control element 1003 may also be a portable device, such as an iPhone or smartphone.

[0141] Figure 3 An embodiment of a lighting device 1000 is also schematically depicted, wherein the lighting device 1000 includes at least one listener node 110 of the present invention for use in the asset tracking system of the present invention.

[0142] The term "multiple" refers to two or more. Furthermore, the terms "multiple" and "several" are used interchangeably.

[0143] Those skilled in the art will understand the terms “substantially” or “basically” and similar terms used herein. The term “substantially” or “basically” may also include embodiments with terms such as “completely,” “entirely,” “all,” etc. Therefore, in embodiments, the adjectives “substantially” or “basically” may also be removed. Where applicable, the term “substantially” or “basically” may also refer to 90% or higher, such as 95% or higher, particularly 99% or higher, even more particularly 99.5% or higher, including 100%. Furthermore, the terms “approximately” and “about” may also refer to 90% or higher, such as 95% or higher, particularly 99% or higher, even more particularly 99.5% or higher, including 100%. For numerical values, it should be understood that the terms “substantially,” “basically,” “approximately,” and “about” may also refer to a range of 90%–110%, such as 95%–105%, particularly 99%–101%, of the numerical values ​​they refer to.

[0144] The term "comprising" also includes embodiments that mean "consisting of".

[0145] The term “and / or” specifically refers to one or more items mentioned before and after “and / or”. For example, the phrase “item 1 and / or item 2” and similar phrases can refer to one or more of item 1 and item 2. The term “comprising” in one embodiment can mean “consisting of”, but in another embodiment it can also mean “containing at least the defined kinds and optional one or more other kinds”.

[0146] Furthermore, the terms first, second, third, etc., used in the specification and claims are used to distinguish between similar elements and are not necessarily used to describe a sequential or chronological order. It should be understood that such terms are interchangeable where appropriate, and the embodiments of the invention described herein can operate in orders other than those described or shown herein.

[0147] During operation, the equipment, apparatus, or system may be described herein—among others. As will be apparent to those skilled in the art, the invention is not limited to the method of operation, or the equipment, apparatus, or system in operation.

[0148] The term "another embodiment" and similar terms may refer to an embodiment that includes features of the previously discussed embodiments, but may also refer to alternative embodiments.

[0149] It should be noted that the above embodiments are illustrative and not limiting of the invention, and those skilled in the art will be able to devise many alternative embodiments without departing from the scope of the appended claims.

[0150] In the claims, any reference numerals placed between parentheses shall not be construed as limiting the claims.

[0151] The use of the verb "comprise" and its variations does not exclude the presence of elements or steps other than those stated in the claims. Unless the context explicitly requires it, throughout the specification and claims, the words "comprise," "comprising," "include," "containing," etc., should be interpreted as encompassing, not exclusive or exhaustive; that is, in the sense of "including but not limited to."

[0152] The article "one" or "a" preceding an element does not preclude the existence of multiple such elements.

[0153] This invention can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In an apparatus claim, device claim, or system claim listing several components, several of these components may be embodied by the same hardware item. The mere fact that certain measures are referenced in mutually different dependent claims does not indicate that a combination of these measures cannot be used advantageously.

[0154] The present invention also provides a control system that can control a device, apparatus, or system, or perform the methods or processes described herein. Furthermore, the present invention provides a computer program product that, when functionally coupled to or executed on a computer included in a device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system.

[0155] The term "control" and similar terms used herein specifically refer at least to determining the behavior of an element or monitoring the operation of an element. Therefore, "control" and similar terms used herein can, for example, refer to applying behavior to an element (determining behavior or monitoring the operation of the element), such as measuring, displaying, actuating, turning on, moving, changing temperature, etc. In addition, the term "control" and similar terms can additionally include monitoring. Therefore, the term "control" and similar terms can include applying behavior to an element, as well as applying behavior to an element and monitoring the element. Control of the element can be accomplished using a control system. Therefore, the control system and the element can be functionally coupled, at least temporarily or permanently. The element can include a control system. In embodiments, the control system and the element may not be physically coupled. Control can be accomplished via wired and / or wireless control. The term "control system" can also refer to multiple different control systems, especially those functionally coupled, and where, for example, one control system can be a master control system, and one or more other control systems can be subordinate control systems.

[0156] The present invention is also applicable to devices, apparatuses, or systems that include one or more features described in the specification and / or shown in the accompanying drawings. The invention also relates to methods or processes that include one or more features described in the specification and / or shown in the accompanying drawings. Furthermore, if a method or an embodiment of the method is described as being performed in a device, apparatus, or system, it will be understood that the device, apparatus, or system is suited to or configured to (perform) the method or an embodiment of the method.

[0157] The various aspects discussed in this patent can be combined to provide additional advantages. Furthermore, those skilled in the art will understand that embodiments can be combined, and more than two embodiments can be combined. Additionally, some features can form the basis of one or more divisional applications.

[0158] Among other things, the present invention relates to a collaborative system and may include at least two steps. In the first step, listeners close to the transmitting tag are notifying and negotiating with each other. Furthermore, a top-level listener may be selected in a distributed manner based on their respective measurements. In the second step, the measurement results of all selected listeners are sent individually by the selected listeners, or by one or more reporting listeners already selected in the first step. The destination of the reports may be the network gateway.

Claims

1. An asset tracking system (100) for tracking tags (10) in a space (500), wherein the tags (10) periodically emit beacon signals (20), wherein the asset tracking system (100) includes a plurality of listener nodes (110) arranged in the space (500) and configured to detect the beacon signals (20), and wherein the asset tracking system (100) includes a control system (300), wherein the control system (300) has access to location data of the plurality of listener nodes (110), wherein in an operating mode: - Each of the plurality of listener nodes (110) determines signal attributes when the beacon signal (20) is detected, wherein the listener node (110) determines a notification delay based on the signal attributes; - Each listener node (110) announces the measurement signal (120) to the relevant proper subset (111) of the plurality of listener nodes (110) after the announcement delay, unless the listener node (110) has received a predetermined number n1 measurement signals (120). - Select one or more report listener nodes (112) from the plurality of listener nodes (110), wherein the one or more report listener nodes (112) are a proper subset of the plurality of listener nodes (110); Each listener node (110) that has notified the relevant proper subset (111) of its measurement signals and has received exactly a second predefined number n2 measurement signals from the relevant proper subset (111) at the time of notification is selected as one of one or more reporting listener nodes (112), where n2 is selected from the range 0-10; - The one or more report listener nodes (112) provide a collection signal (122) to the control system (300), wherein the collection signal (122) includes data related to a plurality of measurement signals (120); The control system (300) determines the position of the tag (10) based on the set signal (122) and the position data.

2. The asset tracking system (100) of claim 1, wherein, The signal attributes are selected from a group consisting of signal strength, signal quality, distance estimation, angle estimation, and phase estimation.

3. The asset tracking system (100) according to claim 2, wherein: - The signal attribute includes signal strength or signal quality, and the notification delay is selected to be inversely proportional to the signal attribute; or The signal attributes include distance estimation, and the notification delay is selected to be proportional to the signal attributes.

4. The asset tracking system (100) according to any one of the preceding claims, wherein n2 is 0.

5. The asset tracking system (100) according to any one of claims 1-3, wherein n2 is n1 - 1.

6. The asset tracking system (100) according to any one of the preceding claims, wherein, The relevant proper subset (111) of each listener node (110) includes all of the plurality of listener nodes (110) that can be reached from the listener node (110) in n hops, where n is selected from the range of 1-2.

7. The asset tracking system (100) according to any one of the preceding claims, wherein, The listener node (110) is integrated into the lighting device (1000).

8. The asset tracking system (100) according to any one of the preceding claims, wherein the plurality of listener nodes (110) comprises 10 listener nodes (110), wherein 10 ≥ 10, and wherein the relevant proper subset (111) comprises 11 listener nodes (110), wherein 11 ≥ 1, and wherein 11 / 10 ≤ 0.5, and wherein the one or more reporting listener nodes (112) comprises 12 listener nodes (110), wherein 12 ≥ 1, and wherein 12 / 10 ≤ 0.

2.

9. The asset tracking system (100) according to any one of the preceding claims, wherein at least a portion of the plurality of listener nodes (110) is included in a mesh network (200).

10. A method for tracking the position (15) of a tag (10) in a space (500), wherein the tag (10) periodically emits a beacon signal (20), wherein a plurality of listener nodes (110) are arranged in the space (500), wherein the listener nodes (110) are configured to detect the beacon signal (20), wherein a control system (300) has access to position data of the plurality of listener nodes (110), wherein the method comprises: - Detect the beacon signal (20) using a detection subset (115) of the listener nodes (110); wherein each listener node (110) in the detection subset (115) is: Determine the signal properties of the beacon signal (20). The notification delay is determined based on the aforementioned signal attributes. After the notification delay, the measurement signal (120) is notified to the relevant proper subset (111) of the plurality of listener nodes (110) unless the listener node (110) has received a predetermined number of measurement signals (120). - Select one or more report listener nodes (112) from the plurality of listener nodes (110), wherein the one or more report listener nodes (112) are a proper subset of the listener nodes (110); Each listener node (110) that has notified the relevant proper subset (111) of its measurement signals and has received exactly a second predefined number n2 measurement signals from the relevant proper subset (111) at the time of notification is selected as one of one or more reporting listener nodes (112), where n2 is selected from the range 0-10; - A collection signal (122) is provided from the one or more report listener nodes (112) to the control system (300), wherein the collection signal (122) includes data related to a plurality of measurement signals (120); The control system (300) determines the position (15) of the tag (10) based on the collection signal (122) and the position data of the plurality of listener nodes (110).

11. The method of claim 10, wherein: - The signal attribute includes signal strength or signal quality, and the notification delay is inversely proportional to the signal attribute; or The signal attributes include distance estimation, and the notification delay is proportional to the signal attributes.

12. The method according to any of the preceding claims 10-11, wherein, The listener node (110) is integrated into the lighting device (1000).

13. The method according to any one of claims 10-12, wherein the plurality of listener nodes (110) comprises l0 listener nodes (110), wherein l0 ≥ 10, and wherein the relevant proper subset (111) comprises n1 listener nodes (110), wherein l1 ≥ 1, and wherein l1 / l0 ≤ 0.5, and wherein the one or more report listener nodes (112) comprises l2 listener nodes (110), wherein l2 ≥ 1, and wherein l2 / l0 ≤ 0.

2.

14. A lighting device (1000) comprising at least one listener node (110) for use in an asset tracking system (100) according to any one of claims 1-9.

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