Asset Tracking System

Abstract

The present invention provides a target tag (10) for object tracking, the target tag (10) being configured to detect listener beacon signals emitted by a plurality of listener nodes (110), the target tag (10) having access to transmission power-related data and receiver sensitivity-related data of the plurality of listener nodes (110), and in a tag operation mode, the target tag (10) being configured to detect the listener beacon signals and determine an associated listener beacon signal strength, determine a tag transmission power based on the associated listener beacon signal strength, the transmission power-related data, the receiver sensitivity-related data, and a predetermined target number of reachable listener nodes, and emit the target beacon signal at the tag transmission power.

Description

Technical Field

[0001] The present invention relates to a target tag for object tracking. The present invention further relates to an asset-tracking system. The present invention further relates to a method for calibrating tags. The present invention further relates to a computer program product.

Background Art

[0002] Target tags are known in the art. For example, US20080224870 describes an apparatus and method for managing the power of radio frequency identification (RFID) tags. The apparatus for managing the power of an RFID tag can effectively reduce the power consumption of the RFID tag by measuring the power intensity of a radio frequency (RF) signal received from an RFID reader and adjusting the level of the transmission power based on the measured power intensity of the signal. See also US2013 / 0337847A1.

Summary of the Invention

Problems to be Solved by the Invention

[0003] An asset tracking system typically includes three types of field devices, namely, (mobile) tags, listener nodes (or "anchors"), and gateways. In such a system, a tag may emit a beacon signal, and a listener node may detect an incoming beacon signal transmitted by the tag and perform measurements such as signal strength measurements. The measurements may typically be performed by a plurality of listener nodes, and the listener nodes may transmit these results to a gateway, which may further process them, for example, by transferring them from the gateway to a positioning engine in a server or the cloud. The listener nodes may be spatially distributed across the space where the tag is to be tracked in order to provide good coverage of the space, and the tag may be located based on signals from a plurality of listener nodes. For example, the positioning engine may estimate that the tag is closest to the listener node that recorded the highest signal strength with respect to the beacon signal. Typically, the beacon signal of a target tag can be picked up by a plurality of listener nodes, and each listener node may report the signal associated with the gateway, which requires a certain network capacity. Therefore, in an asset tracking system, especially in asset tracking deployed in a dense lighting grid and operating with a plurality of target tags, it may be difficult to provide sufficient network capacity to convey all the measurement results, i.e., the required network capacity can be very high in the absence of a significant reduction in communication.

[0004] It may be recognized that the reduction of measurement data and thus the required network capacity may not lead to a significant degradation in performance, but a good method for selecting the listener nodes that need to be reported may not be readily available. In particular, the listener nodes may be spatially dispersed, and the coordination between listener nodes such that a small number of listener nodes are selected to report requires an overhead in communication bandwidth. If not designed carefully, the overhead may be higher than the cost saved by listener nodes not reporting measurement data. Further, the target tags may operate inefficiently with respect to energy consumption, and as a result, the battery life of the target tags may be shortened.

Means for Solving the Problem

[0005] Accordingly, one aspect of the present invention is to provide an alternative asset tracking system that preferably at least partially removes one or more of the above-mentioned disadvantages. The present invention may aim to overcome or improve at least one of the disadvantages of the prior art or to provide a useful alternative. The present invention is described in the set of appended independent and dependent claims.

[0006] Accordingly, in a first aspect, the present invention may provide a target tag for object tracking. The target tag may be configured to detect listener beacon signals emitted by a plurality of listener nodes (of an asset tracking system). The listener beacon signals may include one or more of the transmission power related data and the receiver sensitivity related data of the plurality of listener nodes. The target tag may further be able to access the transmission power related data and / or the receiver sensitivity related data of the plurality of listener nodes, particularly the transmission power related data, or particularly the receiver sensitivity related data. The tag may further be operated in a tag operation mode. In the tag operation mode, the target tag may be configured to execute one or more of a detection stage, a signal processing stage, and an execution stage. In the detection stage, the target tag may be configured to detect (and be configured to detect) the listener beacon signals (of the plurality of listener nodes), and may determine one or more of the associated listener beacon signal strength and the transmission power related data and the receiver sensitivity related data. In the signal processing stage, the target tag may be configured to determine the tag transmission power based on one or more of the associated listener beacon signal strength, the transmission power related data, the receiver sensitivity related data, and a predetermined goal number of reached listener nodes. In the execution stage, the target tag may be configured to emit a target beacon signal with the tag transmission power.Accordingly, in certain embodiments, the present invention provides a target tag for object tracking, the target tag being configured to detect listener beacon signals emitted by a plurality of listener nodes, the target tag being able to access transmission power related data and receiver sensitivity related data of the plurality of listener nodes, and in a tag operation mode, the target tag (i) detecting listener beacon signals and determining associated listener beacon signal strengths, (ii) determining tag transmission power based on the associated listener beacon signal strengths, transmission power related data, receiver sensitivity related data, and a predetermined target number of listener nodes reached, and (iii) being configured to emit a target beacon signal with the tag transmission power.

[0007] The target tag may provide the advantage that the tag transmission power is adjusted based on the (local) characteristics of the asset tracking system and a predetermined target number of listener nodes reached.

[0008] In an asset tracking system, it is common for infrastructure listener nodes to also periodically emit their respective listener beacon signals. This serves the purpose that mobile centric tags or mobile phones can use the listener beacon signals to determine their own positions in order to facilitate indoor navigation applications. The target tag of the present invention may be configured to detect these listener beacon signals and determine an appropriate transmission power to reach a predetermined target number of listener nodes based on the detected listener beacon signals. Accordingly, the transmission power of the target tag may be adjusted to reach (on average) a number of listener nodes that satisfies the desired localization accuracy, which reduces the number of listener nodes having relevant signals to be reported to the gateway and can reduce the overhead communication between listener nodes, thus reducing excessive communication by the listener nodes and reducing the transmission power, which can improve the battery life of the target tag. Accordingly, the present invention may provide a target tag configured to autonomously determine the transmission power by detecting and measuring the listener beacon signals from the listener nodes.

[0009] Accordingly, the present invention may provide a target tag for object tracking, particularly for tracking an object within a space.

[0010] As used herein, the term "target tag" (or "tag") may refer to an item that can be tracked, particularly an item that can be uniquely identified, such as by having a target tag identification. The target tag may be connected to an item that is desired to be tracked (a larger object), such as by being attached to the item or worn by a person. For example, the target tag may include one or more of a sticker, a badge, a wristband, an implant, and a token. Further, the target tag may be configured to emit a wireless signal, such as a radio beacon or a Bluetooth (registered trademark) low energy beacon. Generally, the target tag may be a mobile target tag.

[0011] As used herein, the term "space" may refer to any space in which it may be desirable to track the whereabouts of a target tag. The space may particularly include a building (or a part thereof), such as a shopping mall, a factory, or a hospital (a part thereof). However, the space may be located outdoors. The space may include, for example, a recreation park or a farm. In one embodiment, the term "space" may refer to an office, a store, a warehouse, a theater, a hospitality area, a hospital, a nursing home, a hotel, a plant, an airport, a shopping mall, a factory, a horticulture plant. The term "space" may refer to an indoor space or an outdoor space, particularly an indoor space. As will be apparent to those skilled in the art, generally, the space is not included in the asset tracking system, i.e., the space is not part of the system.

[0012] In one embodiment, the target tag may be configured to detect a listener beacon signal emitted by a plurality of listener nodes, particularly a plurality of listener nodes of an asset tracking system.

[0013] In particular, the plurality of listener nodes may be configured to emit (and in particular, to periodically emit) a listener beacon signal. In particular, each of the plurality of listener nodes may emit its respective listener beacon signal.

[0014] In a further embodiment, the target tag may be able to access transmission power-related data and / or receiver sensitivity-related data of the plurality of listener nodes, in particular transmission power-related data, or in particular receiver sensitivity-related data.

[0015] As used herein, the term "transmission power-related data" may refer to data regarding the power at which a listener node transmits a listener beacon signal. In particular, using this data, the target tag may determine the signal strength loss that occurs as the listener beacon signal travels from each listener node to the target tag, which may be essentially the same signal strength loss expected as the target beacon signal travels from the target tag to each listener node.

[0016] As used herein, the term "receiver sensitivity-related data" may refer to data regarding the minimum signal strength required for a listener node to detect and / or process an incident signal, such as a target beacon signal. In particular, using this data, the target tag may determine the minimum signal strength that the target beacon signal may need to have when arriving at the listener node for the listener node to detect the target beacon signal and / or report a related signal.

[0017] Both the transmission power related data and the receiver sensitivity related data may be related to both hardware and software. For example, the hardware of the listener node may mean that the listener node can only detect target beacon signals having a signal strength exceeding a threshold (when arriving at the listener node). However, further, the listener node may be configured to report related signals only when the signal strength of the detected signal exceeds a second threshold.

[0018] Thus, if the target tag has access to the transmission power related data, the receiver sensitivity related data, and the signal strength of the detected listener beacon signal, the target tag can determine, for each listener node, the transmission power required for the listener node to detect (and report related signals) the target beacon signal.

[0019] As used herein, the phrase "has access to data" and similar phrases may refer to (i) having default data, (ii) having specific data, (iii) receiving default data, and / or (iv) receiving specific data. Thus, in one embodiment, the transmission power related data may include default transmission power related data. In a further embodiment, the transmission power related data may include specific transmission power related data, i.e., specific transmission power related data for one (or more) of a plurality of listener nodes. In a further embodiment, the target tag may include a data carrier in which the transmission power related data is stored. In a further embodiment, the target tag may be configured to receive (such as during operation, e.g., in an operating mode, particularly via a listener beacon signal) the transmission power related data.

[0020] For example, the target tag may include a data carrier that stores default transmission power related data, which by default indicates that the listener node is assumed to transmit the listener beacon signal at a power of 0 dBm. Thus, without further information, the target tag may determine the tag transmission power based on the assumption that the listener node emits at a power of 0 dBm during the signal processing stage. However, the listener node may emit a listener beacon signal that includes, for example, transmission power related data. In particular, each listener beacon signal may include specific transmission power related data regarding the power at which the (respective) listener beacon signal is emitted. Thus, in this example, the target tag that detects the listener beacon signal can access the specific transmission power related data. Generally, when the target tag can access both default and specific transmission power related data regarding the listener node, the target tag will use the specific data during the signal processing stage. Thus, during the signal processing stage, the transmission power related data may be the specific transmission power related data for each listener node if available, or the default transmission power related data if the specific transmission power related data is not available.

[0021] Similarly, during the signal processing stage, the receiver sensitivity related data may be the specific receiver sensitivity related data for each listener node if available, or the default receiver sensitivity related data if the specific receiver sensitivity related data is not available.

[0022] In some embodiments, the target tag may have a tag operational mode. The term "tag operational mode" specifically refers to the operational mode of the tag. The term "operational mode" may be denoted as "controlling mode". The target tag, system, apparatus, or device (further referred to hereinafter) may perform an action in a "mode", "operation mode", or "mode of operation". Similarly, in a method, an action, step, or procedure may be performed in a "mode", "operation mode", or "mode of operation". This does not preclude the target tag, system, apparatus, or device from being adapted to provide another control mode, or a plurality of other control modes. Similarly, this does not preclude one or more other modes from being performed before and / or after performing a mode. However, in some embodiments, a control system (further referred to hereinafter) adapted to provide at least a control mode may be available. If other modes are available, the selection of such a mode may depend on a sensor signal or a (time) scheme, and other options such as performing the mode are possible, but may be performed particularly via a user interface. The operational mode may, in some embodiments, refer to a target tag, system, apparatus, or device that can operate only in a single operational mode (i.e., "on" without further tunability).

[0023] The tag operational mode may include one or more of a detection stage, a signal processing stage, and an execution stage, and in particular, the tag operational mode may include a detection stage, a signal processing stage, and an execution stage.

[0024] In the detection stage, the target tag may be configured to detect the listener beacon signals (of multiple listener nodes) and determine the associated listener beacon signal strengths. Specifically, the target tag may detect the listener beacon signals of at least some of the multiple listener nodes, and for each detected beacon signal, determine the associated listener beacon signal strength.

[0025] As used herein, the term "signal strength" may particularly refer to the power present in the detected beacon signal. In particular, the signal strength may correspond to the Received Signal Strength Indication (RSSI).

[0026] As used herein, terms such as "related" in "related listener beacon signal strength" may refer to the relationship between two features, such as the relationship between the detected listener beacon signal and the determined related listener beacon signal strength, where the related listener beacon signal strength is at least partially based on the detection of the listener beacon signal.

[0027] In the signal processing stage, the target tag may be configured to determine the tag transmission power based on the associated listener beacon signal strength, transmission power related data, receiver sensitivity related data, and a predetermined target number of listener nodes reached.

[0028] As used herein, the term "predetermined goal number" may refer to the goal number of listener nodes that detect (and report related signals) a target beacon signal. As used herein, the term "goal number" may refer to a goal that each number is to be achieved. That is, the target tag may be configured to reach (on average) a number of listener nodes that is as close as possible to the goal number. In a further embodiment, the predetermined goal number may include a lower goal number, i.e., the desired minimum number of reached listener nodes. In a further embodiment, the predetermined goal number may include an upper goal number, i.e., the desired maximum number of reached listener nodes. Also, the term "predetermined goal number" may refer to a plurality of predetermined goal numbers, such as a lower goal number and an upper goal number. Thus, the predetermined goal number may effectively provide a (permissible) range of listener nodes to be reached.

[0029] For example, the predetermined goal number may be 3 (lower goal number) to 5 (upper goal number), and the target tag may determine the transmission power based on the current information at the current tag location such that the target beacon signal will be detected by 3 to 5 listener nodes based on the related listener beacon signal strength, transmission power related data, and receiver sensitivity related data.

[0030] As an alternative to adjusting the tag transmission power, the target tag may notify a plurality of listener nodes to adjust a desired threshold for receiving and processing the target beacon signal.

[0031] Accordingly, the present invention may provide a target tag for object tracking. The target tag may be configured to emit a target beacon signal. The target tag may further be configured to detect a listener beacon signal emitted by a plurality of listener nodes. In particular, each of the plurality of listener nodes may be configured to detect the target beacon signal and, when the target signal strength of the target beacon signal exceeds a detection threshold, report the associated target signal. In one embodiment, the target tag may be able to access transmission power related data and receiver sensitivity related data of the plurality of listener nodes. The target tag may have an operating mode, and in particular, the operating mode may include the execution of one or more of a detection stage, a signal processing stage, and an execution stage. The detection stage may include detecting the listener beacon signal and determining the associated listener beacon signal strength. The signal processing stage may include determining a target beacon signal strength offset based on a predetermined target number of listener nodes reached, the associated listener beacon signal strength, transmission power related data, and receiver sensitivity related data. The signal processing stage may further include determining one or more of (a) the (first) transmission power of the target beacon signal and (b) a detection threshold value based on the target beacon signal strength offset. The execution stage may include executing one or more of (a) emitting the target beacon signal at the (first) transmission power and (b) notifying at least a portion of the plurality of listener nodes to set a detection threshold (for the target tag) at the detection threshold value.

[0032] Thus, in certain embodiments, a target tag is configured to emit a target beacon signal, the target tag is configured to detect a listener beacon signal emitted by a plurality of listener nodes, each of the plurality of listener nodes is configured to detect the target beacon signal and, when the target signal strength of the target beacon signal exceeds a detection threshold, report an associated target signal, the target tag can access transmission power related data and receiver sensitivity related data of the plurality of listener nodes, and in an operating mode, the target tag is configured to detect a listener beacon signal and determine an associated listener beacon signal strength, determine a target beacon signal strength offset based on a predetermined target number of listener nodes that reach, the associated listener beacon signal strength, the transmission power related data and the receiver sensitivity related data, and based on the target beacon signal strength offset, determine one or more of (a) the transmission power of the target beacon signal and (b) the detection threshold, and be configured to perform one or more of (a) emitting the target beacon signal at the transmission power and (b) notifying at least a portion of the plurality of listener nodes to set the detection threshold to the detection threshold.

[0033] Thus, rather than determining a tag transmission power for the target tag to reach a desired number of listener nodes, the target tag may notify the plurality of listener nodes to process the target beacon signal only when the signal strength at which the plurality of listener nodes receive the target beacon signal exceeds a detection threshold.

[0034] This can provide the further advantage that the target beacon signal can have a higher signal / noise ratio since the tag transmission power can be maintained at a higher level.

[0035] As used herein, the term "detection threshold" may refer to the (software level) threshold of the listener node, and the listener node is configured to report a target signal associated only when the signal strength of the detected target beacon signal exceeds the detection threshold.

[0036] The target tag may, in particular, notify at least some of the plurality of listener nodes to set a detection threshold for the target tag, i.e., the detection threshold may remain unchanged for other signals such as other beacon signals.

[0037] As used herein, the term "target beacon signal strength offset" may, in particular, refer to the signal strength difference that results in the target tag reaching a predetermined number of target listener nodes (based on the information currently available to the target tag). For example, if the target beacon signal strength offset is -10 dBm, the tag transmission power may be reduced by 10 dBm, or the detection threshold may be increased by 10, or two combinations such as reducing the tag transmission power by 5 dBm and increasing the detection threshold by 5 dBm may be performed to provide an overall difference of 10 dBm.

[0038] In a further embodiment, the signal processing stage may include determining the transmission power of the target beacon signal based on the target beacon signal strength offset, and the execution stage may include transmitting the target beacon signal at the transmission power.

[0039] In a further embodiment, the signal processing stage may include determining the detection threshold based on the target beacon signal strength offset, and the execution stage may include notifying at least some of the plurality of listener nodes to set the detection threshold to the detection threshold.

[0040] Moreover, it is also possible to combine the adjustment of the tag transmission power and the adjustment of the detection threshold. In particular, the target tag may increase the tag transmission power and increase the detection threshold in order to provide a higher signal / noise ratio while considering a predetermined target number n of the listener nodes.

[0041] In some embodiments, the target beacon signal may include a detection threshold, that is, in some embodiments, the target tag may be configured to notify at least a part of the plurality of listener nodes to set a detection threshold in the detection threshold via the target beacon signal (at the execution stage).

[0042] In some embodiments, the present invention provides a target tag for object tracking, the target tag being configured to detect a listener beacon signal emitted by a plurality of listener nodes, the target tag being able to access transmission power related data and receiver sensitivity related data of the plurality of listener nodes, and in the tag operation mode, the target tag detecting the listener beacon signal and determining the related listener beacon signal strength, and determining the tag transmission power and / or a receiving signal strength threshold based on the related listener beacon signal strength, the transmission power related data, the receiver sensitivity related data, and a predetermined target number of the reached listener nodes, and being configured to indicate in the target beacon signal the receiving signal strength threshold to be applied at the listener when transmitting the target beacon signal with the tag transmission power and / or receiving the (target beacon signal), and in particular, the operation mode may include determining the receiving signal strength threshold based on the related listener beacon signal strength, the transmission power related data, the receiver sensitivity related data, and a predetermined target number of the reached listener nodes, and indicating in the target beacon signal the receiving signal strength threshold to be applied at the listener when receiving.

[0043] In one embodiment, the present invention is a target tag for object tracking, the target tag being configured to detect listener beacon signals emitted by a plurality of listener nodes, the target tag being able to access transmission power related data and receiver sensitivity related data of the plurality of listener nodes, and in a tag operation mode, the target tag detecting listener beacon signals and determining the associated listener beacon signal strength, and determining a (receiver) detection threshold range for each listener node of the plurality of listener nodes based on the associated listener beacon signal strength, transmission power related data, receiver sensitivity related data, and a predetermined target number of listener nodes reached, and in particular being configured to emit a target beacon signal including a detection threshold range for at least some of the plurality of listener nodes, more particularly for each listener node of the plurality of listener nodes. In a further embodiment, the target beacon signal, particularly including the detection threshold range, may be configured to enable each listener node of the plurality of listener nodes to set its respective receiver detection sensitivity to the detection threshold range.

[0044] It will be apparent to those skilled in the art that the target tag may move (in space), and the number of listener nodes that detect the target beacon signal transmitted at a specific transmission power may vary depending on the location of the target tag. Thus, the target tag may, in particular, determine the transmission power based on (local) measurements and use that transmission power as the target tag moves (in space). For example, the target tag may select a tag transmission power such that it reaches four listener nodes according to measurements at its current location. However, as the target tag moves in space, the tag beacon signal may reach fewer or more listener nodes depending on its location, which may depend, inter alia, on whether the listener nodes are arranged in a regular or irregular pattern. In certain embodiments (also see below), the target tag may be configured to (re)execute the tag operation mode after moving further than a movement threshold, or the control system (of the asset tracking system) may instruct the target tag to (re)execute the tag operation mode. Furthermore, the present invention may be particularly beneficial in embodiments where most of the listener nodes are arranged in a regular grid, such that the (re)execution of the tag operation mode may be limited, such as in embodiments where the listener nodes are incorporated into a lighting system.

[0045] In the execution phase, the target tag may emit a target beacon signal at the tag transmission power. Thus, the execution phase may include emitting a target beacon signal at the tag transmission power determined in the signal processing phase.

[0046] In particular, the target tag may be configured to remain in the execution phase until it resumes the operation mode (see below).

[0047] In a further embodiment, during the execution stage, the target tag may be configured to periodically emit a target beacon signal (during the execution stage). In a further embodiment, during the execution stage, the target tag may be configured to emit a target beacon signal according to a regular period, such as every 15 minutes. However, in a further embodiment, the target tag may emit a target beacon signal according to an irregular period, such as a period that varies with time, or each time an external signal is received, or each time the target tag is moved. For example, the target tag may include a (passive) RFID tag and may emit a target beacon signal when it receives an appropriate radio wave.

[0048] In a further embodiment, the target tag may be configured to emit a target beacon signal (essentially) continuously.

[0049] The target beacon signal may include any type of signal that can be detected by a plurality of listener nodes. In one embodiment, the beacon signal may include a wireless communication signal, such as, for example, a Bluetooth® signal, a ZigBee® (beacon packet) signal, a Wi-Fi® (beacon packet) signal, a Li-Fi (beacon packet) signal, an ultra-wideband packet signal, and a Thread signal, selected from the group consisting thereof. In one embodiment, the target beacon signal may include one or more carrier frequencies, particularly a plurality of carrier frequencies.

[0050] The target beacon signal may particularly include a target tag identification code. The target tag identification code may be unique to the target tag and may particularly be suitable for uniquely identifying the target tag. Thereby, different target tags may be distinguished and different (tagged) items may be tracked (independently).

[0051] Also, the target beacon signal may include a target beacon signal sequence number. The target beacon signal sequence number may be unique to the target tag at a given time and may be sequentially incremented until it reaches the maximum number allowed before wrapping around to the minimum number allowed. Thereby, different target beacon signals may be distinguished, and it is known that different target beacon signals from a target tag cannot have two or more target beacon signals from a target tag having the same sequence number, and within a short period of time, for example, by a listener, it may be uniquely identified.

[0052] In one embodiment, the target tag is configured to determine, for each listener node of a plurality of listener nodes, particularly in the signal processing stage, (i) the respective receiver sensitivity R based on receiver sensitivity related data i , (ii) the respective listener transmission power L based on transmission power related data i , and (iii) the respective signal strength S based on the related listener beacon signal strength i of one or more of them.

[0053] In a further embodiment, the predetermined target number of listener nodes reached may include an upper target number. In particular, the target tag is such that for the number of listener nodes among the plurality of listener nodes that is less than or equal to the upper target number, T t ≧R i +L i -S i is applied, and the tag transmission power T t is configured to be determined. In particular, the term "L i -S i " may indicate the expected signal strength loss that may occur when the target beacon signal travels from the target tag to the (i-th) listener node. Therefore, for the target beacon signal to be detected (and / or processed) by the (i-th) listener node, the tag transmission power T tis at least receiver sensitivity R i + predicted signal strength loss L i - S i which may be required. If the predetermined target number includes the upper target number, the formula T t ≧ R i + L i - S i should thus be applied to the upper target number or less of the plurality of listener nodes.

[0054] Similarly, in a further embodiment, the predetermined target number of the reached listener nodes may include the lower target number, and the target tag may be configured to apply T t ≧ R i + L i - S i to determine the transmission power T t for the lower target number or more of the plurality of listener nodes.

[0055] In a further embodiment, the target tag may be configured to minimize the transmission power T t . Thus, the target tag may be configured to minimize the transmission power in view of the predetermined target number of the listener nodes, particularly in view of the lower target number of the listener nodes.

[0056] The transmission power T t may be selected, for example, taking into account any variations in signal loss. Thus, it may be desirable to select a value of T t that is slightly greater than the minimum value determined to reach the predetermined (lower) target number. For example, the tag transmission power T t may be selected to have an added strength T a with respect to the tag transmission power required minimally in view of the predetermined target number of the reached listener nodes. Thus, T t is such that for the lower target number or more of the plurality of listener nodes, T t ≧ R i + L i - S i + T amay be selected to be applied, additional intensity T a is at least 0.1 dBm, for example at least 0.2 dBm, particularly at least 0.5 dBm, for example at least 1 dBm, for example at least 2 dBm. In a further embodiment, the additional intensity T a may be at most 3 dBm, for example at most 2 dBm, particularly at most 1 dBm.

[0057] When detecting a listener beacon signal, the target tag may further be configured to determine the associated listener beacon signal quality. As used herein, the term "signal quality" may particularly refer to the quality of the detected signal. In particular, the quality may be determined, for example, by comparing the detected signal with a (perfect) sigmoidal signal. The signal quality may indicate how informative / trustworthy the signal is. The target tag may be configured to determine (or adjust) a predetermined target number of reached listener nodes based on the associated listener beacon signal quality. For example, the target tag may detect beacon signals of 6 listener nodes, of which 2 of the strongest signals have poor signal quality. Thus, the target tag may set the predetermined target number to 5, for example, such that 3 listener nodes with a listener beacon signal having sufficient signal quality will detect the target beacon signal. Thus, in one embodiment, in the tag operation mode, the target tag may be configured to determine a predetermined target number of reached listener nodes based on a predetermined signal quality requirement.

[0058] In a further embodiment, the predetermined signal quality requirement may be changed by a functionally coupled control system, such as, for example, the control system of an asset tracking system. In particular, the asset tracking system may notify the listener node that, for example, in view of the importance of tracking a related object and / or the localization difficulty, the predetermined signal quality should be adjusted to different values.

[0059] As used herein, the term "signal quality" may particularly refer to the quality of the detected tag beacon signal. In particular, the quality may be determined, for example, by comparing the detected target beacon signal with a (perfect) sigmoidal signal. The signal quality may indicate how informative / trustworthy the signal is.

[0060] In one embodiment, the lower target number may be at least 3, such as at least 4, particularly at least 5, such as at least 7. Generally, detection by three listener nodes may enable decent target tag localization. In a further embodiment, the upper target number may be at most 20, such as at most 15, particularly at most 10, such as at most 8, particularly at most 5.

[0061] In one embodiment, the target tag may be configured to (re)execute the tag operation mode according to a scanning frequency, such as at least daily, at least every few hours, at least every few minutes, for example, at least every 5 minutes, or at least every 2 minutes, or at least every few seconds, for example, at least every 10 seconds, or at least every 2 seconds, for example, at least every 1 second. In a further embodiment, the scanning frequency may be based on one or more of the (target tag's) movement, (target tag's) battery life, and a predefined period. In particular, the target tag may have a predefined period for the scanning frequency, such as every about 5 minutes, but may also be further configured to adjust the scanning frequency based on one or more of the movement and battery life. In particular, the target tag may be configured to shorten the time until the next scan due to movement, i.e., the target tag may be configured to (at least temporarily) reduce the scanning frequency when the target tag moves, especially when the target tag moves beyond a predefined movement threshold. Similarly, the target tag may be configured to increase the time until the next scan based on the battery life, i.e., the target tag may be configured to (at least temporarily) increase the scanning frequency when the battery life drops sharply, especially when it falls below a predefined battery threshold, such as, for example, below 15% of the full battery life, especially below 5% of the full battery life.

[0062] In a further embodiment, the target tag may be configured to (re)execute the tag operation mode upon receiving an (external) tag calibration signal. For example, the asset tracking system may be configured to send a tag calibration signal (for the target tag) when it is considered that the localization of the target tag needs improvement. For example, depending on the situation, when the localization of the target tag becomes more important (when the target is associated with an expert who may be needed immediately), when the signal quality of the target beacon signal detected by the listener node falls below a quality criterion, or when the target beacon signal is no longer detected sufficiently for localization (when the target tag has moved to a part of the space where the density of listener nodes has decreased). As will be apparent to those skilled in the art, further variations of this theme are possible.

[0063] As described above, the listener node may generally emit the listener beacon signal regularly, particularly according to a reporting frequency. However, there may also be an asset tracking system in which the listener node does not emit the listener beacon signal regularly, or the time between listener beacon signals is relatively long. In the latter case, since it can be relatively energy-consuming for the target tag to operate in the detection stage, it may not be desirable for the target tag to remain in the detection stage for a period during which each listener node should have emitted the listener beacon signal (according to its reporting frequency).

[0064] Thus, in one embodiment, the target tag may be configured to emit (i.e., send) a listener beacon signal request signal in a tag operation mode, particularly at the start stage. Thus, the tag operation mode may further include a start stage. In the start stage, the target tag may be configured to emit a listener beacon signal request signal, i.e., the start stage may include the target tag emitting a listener beacon signal request signal. A plurality of listener nodes may be configured to emit a listener beacon signal upon receiving the listener beacon signal request signal. Thus, thereby, each listener node may emit its respective listener beacon signal in a short time window, which means that the target tag may limit the length of the detection stage and may be beneficial for battery life. In particular, the listener beacon signal request signal is a request signal from the target tag to the listener nodes for providing a listener beacon signal. Thus, the listener beacon signal request signal is configured to control a plurality of listener nodes to emit a listener beacon signal upon receiving the listener beacon signal request signal.

[0065] In a further embodiment, the target tag may be able to access the reporting frequency (of a plurality of listener nodes). The reporting frequency may particularly include a default reporting frequency and / or a particular reporting frequency, particularly a default reporting frequency, or a particular reporting frequency.

[0066] In a further aspect, the present invention may provide an asset tracking system that is operably coupled to or includes a target tag according to the present invention, particularly an asset tracking system that includes a target tag. The asset tracking system may be configured to track the target tag in space. The asset tracking system may further include a plurality of listener nodes and a control system. The plurality of listener nodes may be particularly arranged in space and may be particularly configured to emit (periodically) listener beacon signals. The control system may be able to access listener location data and / or map data. The asset tracking system may be operated in a system operation mode. In the system operation mode, each of the plurality of listener nodes may be configured to detect a target beacon signal and provide an associated target signal to the control system, and the control system may be configured to determine the target tag location of the target tag based on the associated target signal, particularly also based on listener location data and / or map data.

[0067] In certain embodiments, the present invention may provide an asset tracking system that includes a target tag, the asset tracking system including a plurality of listener nodes and a control system, the plurality of listener nodes being configured to emit listener beacon signals, and in a system operation mode, (i) each of the plurality of listener nodes being configured to detect a target beacon signal and provide an associated target signal to the control system, and (ii) the control system being configured to determine the target tag location of the target tag based on the associated target signal.

[0068] Accordingly, the present invention may provide an asset-tracking system for tracking a target tag in space. The term "asset-tracking system" may refer to any system configured to track the location and / or movement of one or more objects, particularly target tags, within a space, particularly within a (defined) space (as referenced above).

[0069] The asset-tracking system may include a plurality of listener nodes. Listener nodes are generally also referred to in the art as "tag listeners", "tag locators", "anchor nodes", "tag scanners", "reference nodes", and "sniffers". In certain embodiments, the listener nodes may be configured to detect (or "receive") a target beacon signal, i.e., the listener nodes may be capable of detecting the target beacon signal. In particular, the listener nodes may passively detect the target beacon signal. In further embodiments, the listener nodes may include an antenna configured to detect (or "receive") the target beacon signal.

[0070] The listener nodes may in particular be arranged in a space, i.e., the space in which the target tag is to be tracked. It will be apparent to those skilled in the art that the listener nodes may be arranged in locations that the target tag generally does not reach. For example, the target tag may be used to track a person in an office building, and the listener nodes may be arranged in the lighting system of the office building.

[0071] In one embodiment, at least some of the plurality of listener nodes, particularly each of the plurality of listener nodes, may be configured to adjust a detection threshold to a detection threshold for a target tag when notifying the (plurality of) listener nodes to set a detection threshold for the target tag to a detection threshold for the target beacon signal.

[0072] In one embodiment, the asset tracking system may further include a control system. The control system may be configured to control, in particular, the asset tracking system, particularly the plurality of listener nodes. The control system may be configured to cause the (asset tracking system to) execute a system operation mode, in particular.

[0073] In one embodiment, the control system may be able to access listener location data of the plurality of listener nodes. The location data may include, in particular, data regarding the location of each of the plurality of listener nodes in space, for example, data regarding the room of each listener node, etc., or coordinates of each listener node, etc.

[0074] Also, statements such as "in the operational mode, the control system may determine a target tag location", or "in the operational mode, the control system executes a (step of a) method", or "in the operational mode, the control system may execute a method", and similar statements, in certain embodiments, may be interpreted as the control system being configured to determine a target tag location in the operational mode, or being configured to execute a (step of a) method in the operational mode, etc., (in the operational mode) being configured to perform the indicated action.

[0075] In certain embodiments, the listener beacon signal may include one or more of the transmission power related data and the receiver sensitivity related data of a plurality of listener nodes, particularly one or more of the specific transmission power related data and the specific receiver sensitivity related data, particularly the specific transmission power related data, or particularly the specific receiver sensitivity related data. In particular, each listener node may be configured to emit a listener beacon signal including one or more of the (respective) specific transmission power related data and the (respective) specific receiver sensitivity related data, particularly the (respective) specific transmission power related data, or particularly the (respective) specific receiver sensitivity related data. Thereby, the target tag may access the (specific) transmission power related data and / or the receiver sensitivity related data of a plurality of listener nodes, which may facilitate and / or improve the tag operation mode and may have all related advantages.

[0076] In one embodiment, the control system may be configured to transmit a tag calibration (request) signal. As described above, in one embodiment, the target tag may be configured to execute a tag operation mode upon receiving the tag calibration (request) signal. The control system may be configured to transmit the tag calibration signal, in particular, when one or more of the following conditions are met: the accuracy of the target tag localization is below a (predetermined) accuracy threshold, and the signal quality of the (detected) target beacon signal is below a (predetermined) signal quality threshold. In a further embodiment, the control system may adjust the accuracy threshold and the signal quality threshold based on input data such as input data related to the (temporary) importance of the target tag, or input data from a user interface.

[0077] In one embodiment, the control system may be configured to determine a (suitable) calibration site for the target tag, and in particular, the control system may notify the target tag of the calibration site. For example, in one embodiment, the control system may be configured to determine a calibration site that represents an average area in the space, in particular with respect to the listener node density, such as an average area in the portion of the space where the target tag has historically moved. Thus, the control system may be able to access one or more of the listener location data, map data, and history data. In a further embodiment, the control system may be configured to determine a (suitable) calibration site for the target tag based on one or more of the listener location data, map data, and history data. The history data may in particular include data regarding the locations of previous tags.

[0078] The asset tracking system may in particular be (at least partially) incorporated into other (existing) infrastructure. In particular, in certain embodiments, at least some (of the total number) of the plurality of listener nodes may be incorporated into lighting devices, for example, at least 50% of the total number of the plurality of listener nodes may be incorporated into lighting devices. The lighting device may comprise a low bandwidth wireless communication device for controlling the lighting device. For example, the light generating device may include a wireless communication device such that the light generating device can be remotely controlled, or may be functionally coupled to such a wireless communication device. Thus, in certain embodiments, the wireless communication device may include a listener node.

[0079] As used herein, the term "lighting device" may refer to, for example, one or more of a light generating device, a light control element such as a light switch, and a sensor such as an occupancy sensor or a proximity sensor.

[0080] In further embodiments, the asset tracking system may include a plurality of lighting devices, and at least some of the plurality of listener nodes may be incorporated into the lighting devices.

[0081] In one embodiment, at least 30% of the total number of listener nanonodes may be arranged in a regular grid, such as a regular grid of a lighting device. In a further embodiment, at least 50%, for example at least 60%, particularly at least 70%, for example at least 80%, particularly at least 90%, or 100% of the total number of listener nanonodes may be arranged in a regular grid. As used herein, the term "regular grid" may particularly refer to a pattern formed by the intersection of two or more sets of regularly spaced parallel lines, and in particular, the listener nanonodes may be arranged at the intersections. In a further embodiment, the listener nanonodes included in the regular grid may be arranged at (essentially) the same height, such as on a ceiling. In a further embodiment, the plurality of listener nanonodes may further include one or more listener nanonodes that are not included in the regular grid and are configured at a height different from that of the listener nanonodes configured in the regular grid.

[0082] As used herein, the term "target tag" may refer to a plurality of target tags. In particular, in one embodiment, the asset tracking system may be configured to track a plurality of target tags simultaneously. In a further embodiment, (at least) two of the plurality of target tags may have a predetermined target number of different arriving listener nanonodes.

[0083] In a further aspect, the present invention may provide a method for calibrating a target tag, in particular, the target tag is configured to detect a listener beacon signal emitted by a plurality of listener nodes. The method may include one or more of a detection stage, a signal processing stage, and an execution stage. The detection stage may include detecting a listener beacon signal by the target tag and determining the associated listener beacon signal strength. The signal processing stage may include determining a tag transmission power based on the associated listener beacon signal strength, transmission power related data, receiver sensitivity related data, and a predetermined target number of listener nodes reached. The execution stage may include emitting a target beacon signal at the tag transmission power by the target tag.

[0084] In one embodiment, the present invention includes determining a target beacon signal strength offset based on a predetermined target number of listener nodes reached, the associated listener beacon signal strength, transmission power related data, and receiver sensitivity related data; and based on the target beacon signal strength offset, determining one or more of (a) the (first) transmission power of the target beacon signal and (b) a detection threshold; and performing one or more of (a) emitting the target beacon signal at the (first) transmission power, and (b) notifying at least a portion of the plurality of listener nodes to set a detection threshold (for the target tag).

[0085] In one embodiment, the method may include detecting a listener beacon signal by a target tag and determining an associated listener beacon signal strength; determining a tag transmission power and / or a received signal strength threshold based on the associated listener beacon signal strength, transmission power related data, receiver sensitivity related data, and a predetermined target number of reached listener nodes; and indicating, in a target beacon signal, a received signal strength threshold to be applied by a listener when transmitting a target beacon signal with the tag transmission power and / or receiving (the target beacon signal) by the target tag. In particular, the method may include determining a received signal strength threshold based on the associated listener beacon signal strength, transmission power related data, receiver sensitivity related data, and a predetermined target number of reached listener nodes; and indicating, in a target beacon signal, a received signal strength threshold to be applied by a listener when receiving (the target beacon signal).

[0086] In a further aspect, the invention provides a computer program product comprising instructions for execution on a computer operably coupled to a target tag, which instructions, when executed by a computer, may cause the target tag to execute the method or tag operation mode of the invention, in particular the method of the invention, or in particular the tag operation mode.

[0087] In one embodiment, the computer program product may be executable by a computer operably coupled to the target tag to cause the target tag to execute the method of the invention. In a further aspect, the invention provides a data carrier carrying program instructions which, when executed by a computer operably coupled to a target tag, may cause the target tag to execute the method or tag operation mode of the invention, in particular the method of the invention, or in particular the tag operation mode.

[0088] As used herein, the term "stage" and similar terms may refer to a (time) period (or "phase") of a method and / or mode of operation. Different stages may (partially) (temporally) overlap. For example, the detection stage may generally start before the signal processing stage, but may also (temporally) partially overlap with the signal processing stage. However, for example, the signal processing stage may typically be completed before the execution stage. How stages can be beneficially arranged in time will be apparent to those skilled in the art.

[0089] In a further aspect, the present invention provides a target tag for object tracking, the target tag being configured to detect a listener beacon signal emitted by a plurality of listener nodes, the target tag being able to access transmission power related data and receiver sensitivity related data of the plurality of listener nodes, and in a tag operation mode, the target tag detecting the listener beacon signal and determining the associated listener beacon signal strength, and determining a tag transmission power based on at least one of the associated listener beacon signal strength, the transmission power related data, the receiver sensitivity related data, and a predetermined target number of listener nodes reached, and being configured to emit a target beacon signal with the tag transmission power.

[0090] In a further aspect, the present invention provides a target tag for object tracking, the target tag being configured to detect listener beacon signals emitted by a plurality of listener nodes, the target tag being able to access transmission power related data and receiver sensitivity related data of the plurality of listener nodes, and in a tag operation mode, the target tag detecting listener beacon signals, determining the related listener beacon signal strength, determining a detection threshold range based on at least one of the related listener beacon signal strength, transmission power related data, receiver sensitivity related data, and a predetermined target number of listener nodes reached, and being configured to emit a target beacon signal including the detection threshold range to each listener node of the plurality of listener nodes, the target beacon signal enabling each listener node to set its receiver detection sensitivity to the detection threshold range.

[0091] Advantages and / or embodiments of the first object of the present invention may be applied mutatis mutandis to the above further aspect of the present invention.

Brief Description of the Drawings

[0092] Here, embodiments of the present invention will be described by way of example only with reference to the accompanying schematic diagrams in which corresponding reference numerals indicate corresponding parts. The schematic diagrams are not necessarily to scale.

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0093] Figure 1 schematically shows an embodiment of a target tag 10 for object tracking. In the illustrated embodiment, the target tag 10 is configured to detect listener beacon signals emitted by a plurality of listener nodes 110 (of the asset tracking system 100). In particular, the target tag 10 can access transmission power related data and receiver sensitivity related data of the plurality of listener nodes 110. In the tag operation mode, the target tag (i) detects the listener beacon signal (in the detection stage) and determines the associated listener beacon signal strength, and (ii) determines the tag transmission power T based on the associated listener beacon signal strength, transmission power related data, receiver sensitivity related data, and a predetermined target number of the reaching listener nodes in the signal processing stage t and (iii) may be configured to emit a target beacon signal with the tag transmission power T t in the execution stage.

[0094] For visualization purposes, the tag transmission power T t is illustrated as a circle around the target tag 10 indicating the area where the listener nodes 110 need to be present to detect (and / or process) the target beacon signal. This is a simplified representation, and it will be apparent to those skilled in the art that, for example, different receiver sensitivities of different listener nodes 110 may not be considered.

[0095] In the illustrated embodiment, the target tag 10 may have a default setting of emitting a target beacon signal with a default transmission power T d so that six different listener nodes 110, 110a, 110b, 110c, 110d, 110e, 110f can be reached. However, three listener nodes may be sufficient for accurate localization. Thus, the default transmission may be excessive for the space 500 where the target tag 10 is currently located.

[0096] The target tag 10 may be able to access the transmission power related data and the receiver sensitivity related data of a plurality of listener nodes 110. In the illustrated embodiment, the target tag may, in particular, be able to access the transmission power related data and the receiver sensitivity related data of each of the listener nodes 110a, 110b, 110c, 110d, 110e, and 110f. Further, in the detection stage, the target tag may obtain the listener beacon signal strength related to the listener beacon signals of the plurality of listener nodes 110, in particular, each listener node 110 of the plurality of listener nodes 110a, 110b, 110c, 110d, 110e, and 110f.

[0097] In particular, for each listener node 110 of the plurality of listener nodes 110, the target tag 10 may determine the (respective) receiver sensitivity R i based on the receiver sensitivity related data, the (respective) listener transmission power L i based on the transmission power related data, and the (respective) signal strength S i based on the related listener beacon signal strength. Based on this information, the target tag 10 may determine the (respective) transmission power T i required for each listener node 110 to detect the target beacon signal. Specifically, in one embodiment, T i may be determined according to T i =R i +L i -S i . Thus, with respect to the embodiment of FIG. 1A, the target tag 10 may be able to access the information summarized in Table 1. TIFF0007696421000001.tif75121

[0098] Therefore, according to the data available to the tag, the target beacon signal emitted from target 10 at a transmission power of -15 dBm is sufficient for detection by listener nodes 110b and 110e, while the target beacon signal emitted from target 10 at a transmission power of -10 dBm would also be sufficient for detection by listener node 110c.

[0099] In a further embodiment, a predetermined target number of reaching listener nodes 110 may include a top target number n U and target tag 10 may be for the top target number n among a plurality of listener nodes 110 U For the following, T t ≧T i is applied, that is, for the top target number n among a plurality of listener nodes 110 U For the following, T t ≧R i +L i -S i is applied, and the tag transmission power T t may be configured to be determined. In one embodiment, the top target number n U may be at most 20, for example at most 15, particularly at most 10, for example at most 8, particularly at most 5. For example, with respect to the information in Table 1, when n U is 5, T t must be less than the maximum T i which is -3 dBm (since there are six listener nodes). Thus, for the above example, when n U = 5, T t < -3 dBm.

[0100] Therefore, in one embodiment, the target tag may be configured to determine the tag transmission power T t in accordance with the following (pseudo-)optimization problem. TIFF0007696421000002.tif22109 Here, m is the total number of (relevant) listener nodes, and T minis the minimum transmission power that a (hardware-determined or software-determined) target tag can emit, and T max is the maximum transmission power that the target tag 10 can emit.

[0101] In a further embodiment, a predetermined target number of the reachable listener nodes 110 may include a lower target number n L and the target tag 10 is for at least the lower target number n L of the listener nodes 110 among the plurality of listener nodes 110, T t ≧T i is applied, that is, for at least the lower target number n L of the listener nodes 110 among the plurality of listener nodes 110, T t ≧R i +L i -S i is applied, and the transmission power T t may be configured to be determined. In one embodiment, the lower target number n L may be at least 3, for example at least 4, particularly at least 5, for example at least 7. For example, regarding the information in Table 1, when n L is 3, T t must be greater than the third smallest T i which is -14 dBm. Thus, regarding the above example, when n L = 3, T t ≧ -14 dBm.

[0102] Thus, in a further embodiment, the target tag may be configured to determine the tag transmission power T t according to the following (quasi-)optimization problem. TIFF0007696421000003.tif23106

[0103] In a further embodiment, the predetermined target number includes both a lower target number n L and an upper target number n U , and in particular, n U ≧nL It may be. For example, regarding the information in Table 1, when n L = 3 and n U = 5, T t is the third smallest T, which is -14 dBm, i is greater than that of -3 dBm, and the largest T i must be smaller. Therefore, regarding the above example, -14 dBm ≤ T t < -3 dBm.

[0104] Therefore, in a further embodiment, the target tag may be configured to determine the tag transmission power T t according to the following (quasi) optimization problem. TIFF0007696421000004.tif29108

[0105] In one embodiment, the target tag 10 may be configured to minimize the transmission power T t . Therefore, in one embodiment, the (quasi) optimization problem may include a minimization criterion. For example, regarding the example in Table 1, when n L is 3 and n U is 5, T t may be selected to be -14 dBm from the perspective of the minimization criterion.

[0106] Therefore, in one embodiment, the (quasi) optimization problem may include, for example, the following. TIFF0007696421000005.tif23108

[0107] Similarly, the target tag may be configured to maximize the transmission power T t . Therefore, in one embodiment, the (quasi) optimization problem may include the following. TIFF0007696421000006.tif21108

[0108] In practice, T is slightly larger than the minimum determined to reach a given (sub)target number. t For example, it may be desirable to select a value for the tag transmission power T t is the minimum required tag transmission power boost T given a given target number of listener nodes 110 reached. a and the additional strength T a may be at least 0.1 dBm, such as at least 0.2 dBm, in particular at least 0.5 dBm, such as at least 1 dBm, for example at least 2 dBm. a may be at most 3 dBm, for example at most 2 dBm, in particular at most 1 dBm.

[0109] As an alternative to adjusting tag transmission power as described above, the target tag may inform listener nodes 110 to adjust their desired thresholds for receiving and processing the target beacon signal. In the above example, the target tag 10 may inform listener node 110 to set its detection threshold in the range of -82 dBm and -88 dBm. In this way, listener nodes 110b, 110c, and 110e will be able to report the target beacon signal because their received signal strength will exceed the detection threshold level, while the other listener nodes 110 will not.

[0110] In particular, with respect to the above formula, the target tag is the S of (at least a portion of) the multiple listener nodes. i Thus, the pseudo-optimization problem may include: TIFF0007696421000007.tif28106

[0111] It will be apparent to one skilled in the art that pseudo-optimization problems may also be combined. For example, in a further embodiment, the pseudo-optimization problem may include: TIFF0007696421000008.tif29107

[0112] Thus, in one embodiment, the target tag 10 is configured to emit a target beacon signal, the target tag 10 is configured to detect a listener beacon signal emitted by a plurality of listener nodes 110, each of the plurality of listener nodes 110 is configured to detect the target beacon signal and, when the target signal strength of the target beacon signal exceeds a detection threshold, report the associated target signal, the target tag 10 can access the transmission power related data and receiver sensitivity related data of the plurality of listener nodes 110, and in the operating mode, the target tag 10 is configured to detect the listener beacon signal and determine the associated listener beacon signal strength, determine a target beacon signal strength offset based on a predetermined target number of listener nodes 110 that reach, the associated listener beacon signal strength, the transmission power related data and the receiver sensitivity related data, based on the target beacon signal strength offset, determine one or more of (a) the transmission power of the target beacon signal and (b) the detection threshold, and perform one or more of (a) emitting the target beacon signal with the transmission power and (b) notifying at least a portion of the plurality of listener nodes 110 to set the detection threshold to the detection threshold.

[0113] In a further embodiment, the target beacon signal may include an instruction for at least some of the plurality of listener nodes 110 to adjust the detection threshold.

[0114] In one embodiment, the target tag 10 is configured to detect listener beacon signals emitted by a plurality of listener nodes, the target tag 10 can access transmission power related data and receiver sensitivity related data of the plurality of listener nodes 110, and in the tag operation mode, the target tag 10 detects listener beacon signals and determines the associated listener beacon signal strength, and based on the associated listener beacon signal strength, transmission power related data, receiver sensitivity related data, and a predetermined target number of listener nodes 110 reached, determines a (receiver) detection threshold range for each listener node 110 of the plurality of listener nodes 110, and is configured to emit a target beacon signal including the detection threshold range, in particular for at least some of the plurality of listener nodes 110, more particularly for each listener node 110 of the plurality of listener nodes 110. In a further embodiment, the target beacon signal, in particular including the detection threshold range, may be configured to enable each listener node 110 of the plurality of listener nodes 110 to set its respective receiver detection sensitivity to the detection threshold range.

[0115] In a further embodiment, the predetermined target number may include a desired target number, and the target tag may be configured to minimize the deviation between the target number of desired reached nodes and the number of actually reached nodes.

[0116] FIG. 1 further schematically shows an embodiment of an asset tracking system 100 including a target tag 10. In the illustrated embodiment, the asset tracking system is configured to track the target tag 10 in a space 500. The asset tracking system 100 includes a plurality of listener nodes 110 and a control system 300. The plurality of listener nodes 110 are disposed in the space 500 and are configured to emit listener beacon signals. The system 100 has a system operation mode in which (i) each of the plurality of listener nodes 110 is configured to detect a target beacon signal (of the target tag) and provide an associated target signal to the control system 300, and (ii) the control system 300 may be configured to determine the target tag location of the target tag 10 based on the associated target signal.

[0117] FIG. 2 schematically shows a tag operation mode 20 and a system operation mode 200.

[0118] The tag operation mode 20 may include a detection stage 22, a signal processing stage 23, and an execution stage 24. In the detection stage 22, the target tag 10 may be configured to detect a listener beacon signal and determine an associated listener beacon signal strength. In the signal processing stage 23, the target tag 10 may be configured to determine a tag transmission power T based on the associated listener beacon signal strength, transmission power related data, receiver sensitivity related data, and a predetermined target number of reaching listener nodes. t In the execution stage 24, the target tag 10 may be configured to emit a target beacon signal at the tag transmission power T. In a further embodiment, the target beacon signal may include an instruction for the plurality of listener nodes 110 to adjust a detection threshold. t

[0119] In particular, as shown in FIG. 2, the execution stage 24 may be repeated a plurality of times. The execution stage 24 may be repeated until the tag operation mode 20 is (re)executed and, for example, restarted in the detection stage.

[0120] In one embodiment, the target tag 10 is configured to (re)execute the tag operation mode according to the scanning frequency. In particular, the scanning frequency may be based on one or more of movement, battery life, and a predefined period. In a further embodiment, the target tag 10 may be configured to (re)execute the tag operation mode when receiving an (external) tag calibration signal.

[0121] In one embodiment, the target tag 10 may be configured to remain in the execution stage even when the target tag 10 is turned off and then turned on again, that is, the target tag may be configured to execute the tag operation mode only according to one or more of the scanning frequency and the tag calibration signal.

[0122] In a further embodiment, the operation mode 20 may further include a start stage 21. In the start stage 21, the target tag may be configured to emit a listener beacon signal request signal. In particular, in one embodiment (of the system), a plurality of listener nodes 110 are configured to emit a listener beacon signal when receiving the listener beacon signal request signal. Thus, the listener beacon signal request signal is configured to control a plurality of listener nodes to emit a listener beacon signal when receiving the listener beacon signal request signal.

[0123] System operation mode 200 may include a beacon detection stage 201 and a localization stage 202. In the beacon detection stage 201, each of the plurality of listener nodes 110 may be configured to detect a target beacon signal and provide a related target signal to the control system 300. All of the listener nodes 110 may be configured to detect the target beacon signal, but typically only a first subset of the listener nodes 110 may detect the target beacon signal, and typically only a second subset (of the first subset) may report the related target signal to the control system 300, which will be apparent to those skilled in the art.

[0124] In the localization stage 202, the control system 300 may be configured to determine the target tag location of the target tag 10 based on the related target signal. In certain embodiments, the control system 300 may be configured to determine the target tag location of the target tag 10 based on the related target signal and one or more of the listener location data and / or map data.

[0125] FIG. 2 further schematically shows a method for calibrating the target tag 10, where the target tag 10 is configured to detect listener beacon signals emitted by a plurality of listener nodes 110. The method includes a detection stage 22 that includes detecting the listener beacon signal by the target tag 10 and determining the related listener beacon signal strength, a signal processing stage 23 that includes determining tag transmit power based on the related listener beacon signal strength, transmit power related data, receiver sensitivity related data, and a predetermined target number of listener nodes reached, and an execution stage 24 that includes emitting a target beacon signal at the tag transmit power by the target tag 10.

[0126] FIG. 3 schematically shows another embodiment of the asset tracking system 100 in which a plurality of listener nodes 110 (at least a portion of the total number thereof) are incorporated into the lighting device 1000. In particular, FIG. 3 schematically shows a lighting device 1000 including a light generating device such as a lamp 1001 and a lighting fixture 1002, and a lighting control element 1003 such as a user interface, such as a graphical user interface. Reference numeral 1010 indicates the light generated by the lighting device 1000. In particular, this light is visible light such as white light. Also, the lighting control element 1003 may be a portable device such as an I-phone or a smart phone.

[0127] FIG. 3 also schematically shows an embodiment of the lighting device 1000 in which the lighting device 1000 includes at least one of the listener nodes 110 of the present invention for use in the asset tracking system 100 of the present invention.

[0128] The term "plurality" refers to two or more. The terms "a plurality of" and "a number of" may be used interchangeably.

[0129] The terms "substantially" or "essentially" in this specification would be understood by those skilled in the art. The terms "substantially" or "essentially" may include embodiments using terms such as "entirely", "completely", "all", etc. Thus, in embodiments, the adjectives substantially or essentially may sometimes be deleted. When applicable, the term "substantially" or the term "essentially" may be related to 90% or more, for example 95% or more, particularly 99% or more, more particularly 99.5% or more, for example 100%. Further, the terms "about" and "approximately" may be related to 90% or more, for example 95% or more, particularly 99% or more, more particularly 99.5% or more, for example 100%. For numerical values, it should be understood that the terms "substantially", "essentially", "about", and "approximately" may be related to a range of 95% to 105%, particularly 99% to 101%, etc., 90% to 110% of the value(s) they refer to.

[0130] The term "comprise" includes embodiments where the term "comprises" means "consists of".

[0131] The term "and / or" is particularly related to one or more of the items mentioned before and after "and / or". For example, phrases such as "item 1 and / or item 2", and similar phrases can be related to one or more of item 1 and item 2. The term "comprising" may, in one embodiment, refer to "consisting of", but in another embodiment, may also refer to "containing at least the defined species and optionally one or more other species".

[0132] Furthermore, terms such as first, second, third, etc. in the specification and claims are used to distinguish similar elements and are not necessarily used to describe a sequential or chronological order. Such terms are interchangeable under appropriate circumstances, and it should be understood that the embodiments of the present invention described herein are operable in orders other than those described or illustrated herein.

[0133] A device, apparatus, or system may be described herein, among other things, as being in operation. As will be apparent to those skilled in the art, the present invention is not limited to a method of operation or a device, apparatus, or system while in operation.

[0134] The term "further embodiments" and similar terms may refer to embodiments that incorporate the features of the foregoing embodiments, but may also refer to alternative embodiments.

[0135] Note that the above-described embodiments are illustrative and not limiting of the present invention, and those skilled in the art can design many alternative embodiments without departing from the scope of the appended claims.

[0136] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0137] The use of the verb “to comprise” and its conjugations does not exclude the presence of elements or steps other than those recited in the claims. Unless the context clearly dictates otherwise, throughout the specification and claims, the terms “comprise,” “comprising,” “include,” “including,” “contain,” “containing,” etc. are to be construed in an inclusive sense, i.e., in the sense of “including, but not limited to,” rather than in an exclusive or exhaustive sense.

[0138] The articles “a” or “an” preceding an element do not exclude the presence of a plurality of such elements.

[0139] The present invention may be implemented by hardware including several individual elements and, preferably, by a computer suitably programmed. In claims listing several means, device claims, or system claims, several of these means may be embodied by the same item of hardware. The mere fact that certain means are recited in mutually different dependent claims does not indicate that a combination of these means cannot be used advantageously.

[0140] The present invention also provides a control system that can control a device, apparatus, or system, or execute a method or process described herein. Still further, the present invention also provides a computer program product that, when executed on a computer that is functionally coupled to or included in a device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system.

[0141] The term "control" and like terms refer, among other things, at least to determining the behavior of an element or supervising the execution of an element. Thus, as used herein, the terms "control" and like terms may refer to, for example, measuring, displaying, actuating, opening, shifting, changing the temperature, etc., imposing behavior on an element (determining the behavior of an element or supervising the operation of an element), among other things. Additionally, the term "control" and like terms may further include monitoring. Thus, the term "control" and like terms may include imposing behavior on an element, or may include imposing behavior on an element and monitoring the element. Control of an element can be performed using a control system. Thus, the control system and the element may be functionally coupled, at least temporarily or permanently. The element may include a control system. In certain embodiments, the control system and the element may not be physically coupled. Control can be effected via wired and / or wireless control. The term "control system" refers, among other things, to a plurality of different control systems that are functionally coupled, for example, one of which may be a master control system and one or more others may be slave control systems.

[0142] The present invention further applies to a device, apparatus, or system that includes one or more of the features described in the specification text and / or shown in the accompanying drawings. The present invention further relates to a method or process that includes one or more of the features described in the specification text and / or shown in the accompanying drawings. Further, where it is stated that a method or method embodiment is executed in a device, apparatus, or system, it will be understood that the device, apparatus, or system is respectively suitable or configured for (executing) the method or method embodiment.

[0143] The various aspects discussed in this patent can also be combined to provide further advantages. Moreover, those skilled in the art will understand that embodiments can be combined, and that it is also possible to combine three or more embodiments. Further, some of the features may form the basis for one or more divisional applications.

[0144] In particular, the present invention includes a target tag configured to adjust the transmission power of a target beacon signal in view of the desired number of listener nodes that detect the target beacon signal and report the associated signal to a control system. To this end, the target tag may determine the signal loss that occurs as a listener beacon signal emitted from a listener node travels to the target tag, and may correspondingly adjust the transmission power, also taking into account the transmission power and sensitivity of the listener node.

Claims

1. A target tag for object tracking, the target tag being configured to detect listener beacon signals emitted by a plurality of listener nodes, the listener beacon signals including one or more of transmission power related data and receiver sensitivity related data of the plurality of listener nodes, the target tag being able to access the transmission power related data and the receiver sensitivity related data of the plurality of listener nodes, and in a tag operation mode, the target tag detects the listener beacon signal and determines one or more of the associated listener beacon signal strength and the transmission power related data and the receiver sensitivity related data, determines a tag transmission power based on the associated listener beacon signal strength, the transmission power related data, the receiver sensitivity related data, and a predetermined target number of reached listener nodes, and emits a target beacon signal with the tag transmission power. A target tag configured as such.

2. The predetermined target number of the reached listener nodes includes an upper target number. For each listener node of the plurality of listener nodes, the target tag determines a receiver sensitivity R based on the receiver sensitivity related data, a listener transmission power L based on the transmission power related data, and a signal strength S based on the associated listener beacon signal strength. The target tag determines the tag transmission power T for no more than the upper target number of the plurality of listener nodes such that T ｉ ≧ R ｉ + L ｉ - S ｔ is applied. The target tag according to claim 1, configured to determine the tag transmission power T as such. ｉ + L ｉ - S ｉ is applied. The target tag according to claim 1, configured to determine the tag transmission power T as such. ｔ The target tag according to claim 1, configured as such.

3. The predetermined target number of the reached listener nodes includes a lower target number. The target tag determines the tag transmission power T for no less than the lower target number of the plurality of listener nodes such that T ｔ≥R ｉ +L ｉ −S ｉ configured to determine the transmission power T so as to apply ｔ the target tag according to claim 2. **Claim 4** The target tag is configured to minimize the transmission power T ｔ the target tag according to claim 2 or 3. **Claim 5** In the tag operation mode, the target tag is configured to determine a predetermined number of target reachable listener nodes based on a predetermined signal quality requirement, the target tag according to any one of claims 1 to 4. **Claim 6** The lower target number is at least 3, the target tag according to claim 3, claim 4 dependent on claim 3 or claim 5 dependent on claim 3. **Claim 7** The target tag is configured to execute the tag operation mode according to the scanning frequency, the scanning frequency being based on one or more of movement, battery life, and a predefined period, or configured to execute the tag operation mode when receiving a tag calibration signal, the target tag according to any one of claims 1 to 6. **Claim 8** In the tag operation mode, the target tag is configured to issue a listener beacon signal request signal, and the listener beacon signal request signal is configured to control the plurality of listener nodes to issue the listener beacon signal when receiving the listener beacon signal request signal, the target tag according to any one of claims 1 to 7. **Claim 9** A target tag for object tracking, the target tag being configured to detect listener beacon signals emitted by a plurality of listener nodes, the target tag being able to access transmission power related data and receiver sensitivity related data of the plurality of listener nodes, and in a tag operation mode, the target tag detects the listener beacon signal and determines the associated listener beacon signal strength, determines a detection threshold range based on the associated listener beacon signal strength, the transmission power related data, the receiver sensitivity related data, and a predetermined target number of listener nodes reached, and emits a target beacon signal including the detection threshold range to each of the plurality of listener nodes, is configured to wherein the target beacon signal enables each listener node to set its receiver sensitivity to the detection threshold range, the target tag. **Claim 10** An asset tracking system including the target tag according to any one of claims 1 to 9, the asset tracking system including a plurality of listener nodes and a control system, the plurality of listener nodes being configured to emit listener beacon signals, and in a system operation mode, each of the plurality of listener nodes is configured to detect a target beacon signal and provide an associated target signal to the control system, wherein the control system is configured to determine a target tag location of the target tag based on the associated target signal, the asset tracking system. **Claim 11** The asset tracking system according to claim 10, wherein the control system is configured to transmit a tag calibration signal, and the target tag is configured to execute a tag operation mode when receiving the tag calibration signal. **Claim 12** The asset tracking system according to claim 10 or 11, wherein at least a part of the total number of the plurality of listener nodes is incorporated into an illumination device.

13. A method for calibrating a target tag, the target tag being configured to detect a listener beacon signal emitted by a plurality of listener nodes, the listener beacon signal including one or more of transmission power related data and receiver sensitivity related data of the plurality of listener nodes, the method comprising: detecting the listener beacon signal by the target tag and determining one or more of the associated listener beacon signal strength, the transmission power related data, and the receiver sensitivity related data; determining a tag transmission power based on the associated listener beacon signal strength, the transmission power related data, the receiver sensitivity related data, and a predetermined target number of listener nodes reached; transmitting a target beacon signal at the tag transmission power by the target tag; A method comprising the steps of:

14. A computer program comprising instructions for execution on a computer operatively coupled to a target tag, the instructions causing the computer to perform the method according to claim 13 when executed by the computer.

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