Luminaire with a communication unit for an ultra-wideband (UWB) radio communication

Abstract

A luminaire comprising a communication unit for ultra-wideband (UWB) radio communication, and a data storage is provided. The luminaire is configured to discover, using the communication unit, neighboring luminaires within a vicinity of the luminaire, measure, using the communication unit, a distance to each discovered neighboring luminaire, and store in the data storage for each discovered neighboring luminaire the measured distance in association with an address of the discovered neighboring luminaire. Further, a luminaire comprising a communication unit for UWB radio communication, and a detection unit for detecting an object in a vicinity of the luminaire is provided. The luminaire is configured to detect, using the detection unit, an object, and in response to detecting the object, generate and transmit, using the communication unit, a message informing on the detection of the object and on an address of the luminaire that detected the object and initially transmitted the message.

Description

[0001] The present invention relates to luminaires with a communication unit for an ultra-wideband (UWB) radio communication and a system comprising two luminaires, wherein each luminaire has a communication unit for an UWB radio communication

[0002] The present invention is in the field of swarm control of luminaires, i.e. a luminaire of multiple luminaire can control illumination of other luminaires of the multiple luminaire by wirelessly transmitting a message.

[0003] A lighting system comprising multiple luminaires and sensors usually has a fixed configuration on how the system works. For example, when a sensor of the system detects an object, such as a person, one or more predefined luminaires may be turned on for providing illumination. Due to the fixed configuration always the same luminaires are turned on when an object is detected.

[0004] In a lighting system using swarm control (may be referred to as swarm control lighting system) a luminaire that detects the object (e.g. the person) may transmit a short distance message to other luminaires nearby. Nearby luminaires may adjust the light level to be lower than the light level of the luminaire that detected the object. For example, the further away the nearby luminaries from the luminaire that detected the object, the lower the light level may be. Herein, the terms "light intensity" and "light level" may be used as synonyms.

[0005] For the communication of the short distance message infrared sensors may be used. Infrared sensors are short range devices, which do not have well defined security protocols, e.g. no provisioning needed. As infrared works in short range, they are more difficult to attack from outside. In case of indoor illumination, infrared waves radiated by a luminaire may be reflected from the ceiling or floor to nearby devices. That is, such reflections may be used for the wireless communication.

[0006] There are scenarios where infrared based systems to not work well. Such scenarios may include: a dark or black ceiling and / or floor; a very high ceiling (i.e. distance from the luminaire radiating the infrared wave to the ceiling is too great for the infrared wave to reach the ceiling); the ceiling may have technical pipes and / or rails negatively affecting a reflection of infrared waves at the ceiling; distance between luminaires is too high for infrared communication between them; infrared communication is only usable on free standing luminaires since they need to have some free space to reflect infrared waves on the ceiling; and fade gradient of illumination in a swarm system is limited to 2 or 3 levels, due to technology limitations.

[0007] Therefore, it is an object of the present invention to provide a luminaire that allows implementing an improved swarm control lighting system. It may be an object of the present invention to provide a luminaire that allows implementing a swarm control lighting system, while overcoming at least one of the above-described drawbacks.

[0008] These and other objects, which become apparent upon reading the following description, are solved by the subject matter of the independent claim. The dependent claims refer to preferred embodiments of the invention.

[0009] According to a first aspect of the invention, a luminaire is provided. The luminaire comprises a communication unit for an ultra-wideband (UWB) radio communication, and a data storage. The luminaire is configured to discover, using the communication unit, neighboring luminaires within a vicinity of the luminaire. The luminaire is configured to measure, using the communication unit, a distance to each discovered neighboring luminaire. The luminaire is configured to store in the data storage for each discovered neighboring luminaire the measured distance in association with an address of the discovered neighboring luminaire.

[0010] Using the UWB radio communication has the advantage that it is a short-range communication technology, wherein there is no need of the UWB radio waves to be reflected on a ceiling or a floor for the wireless communication. As a result, the characteristic of the ceiling and / or floor (e.g. color, height, what elements are present at the ceiling or floor etc.) do not have an influence on the wireless communication. Moreover, since there is no need of a reflection of waves at the ceiling, the UWB radio communication allows the luminaire to be used outside, e.g. as a street luminaire. In case the luminaire is used indoor, a distance between the luminaire and the ceiling has no influence on the wireless communication. Furthermore, the UWB radio waves allow a distance measurement with high precision. As a result, a fade gradient of illumination in a swarm system is not limited due to the accurate distance measurement between neighboring luminaires. The communication unit may be used for the distance measurement and the wireless communication, which reduces number of elements in the luminaire for different functions and, thus, allows decreasing size and costs of the luminaire. In contrast to infrared communication, the UWB radio communication does not need the communication unit to be visible and / or to be arranged outside a housing of the luminaire. The communication unit may be arranged inside the luminaire's housing, e.g. as a part of the internal electronics and / or components of the luminaire. Since UWB radio communication is a short-range communication technology the wireless communication is more difficult to be attacked from outside, e.g. from outside a building when the luminaire is installed inside the building. UWB radio communication allows using a custom mesh-like protocol, where luminaires can communicate with each other without any provisioning or need to form a network. UWB radio communication allows using a pre-shared key encryption to protect the communication between luminaires and thus protecting from attacks a lighting system comprising multiple luminaires communicating with each other.

[0011] The luminaire may be an indoor luminaire or an outdoor luminaire. For example, the luminaire may be a suspended luminaire, a ceiling mounted luminaire, a wall mounted luminaire, a ground mounted luminaire, a free-standing luminaire, a desk luminaire etc. For example, the luminaire may be a street luminaire, garden luminaire etc. The luminaire may comprise one or more light emitting diodes (LEDs) as its light source. The luminaire is not limited to a specific type of luminaire.

[0012] The communication unit may comprise one or more antennas for the UWB radio communication. The communication unit may be configured to transmit a message by radiating UWB radio waves (in response to being fed with an UWB radio signal). The communication unit may be configured to receive a message by receiving UWB radio waves. The present invention is not limited to a specific type of communication unit for UWB radio communication. The communication unit may be referred to as "UWB radio communication unit". The term "communication module" may be used as a synonym for the term "communication unit".

[0013] The term "memory" may be used as a synonym for the term "data storage". The data storage may comprise random access memory (RAM) and / or flash memory. The present invention is not limited to a specific type of data storage.

[0014] The vicinity of the luminaire may correspond to an area of the luminaire, in which wireless communication using UWB radio communication is possible. That is, the vicinity of the luminaire may be the area that can be covered by the UVB radio communication provided by the communication unit of the luminaire. The neighboring luminaires, which are discovered by the luminaire using the communication unit, are luminaires in an environment of the luminaire that are reachable by the UWB radio communication (e.g. UWB radio link).The distance to a discovered neighboring luminaire may corresponds to the distance between a location of the luminaire (i.e. the location where the luminaire is installed) and the location of the discovered neighboring luminaire (i.e. the location where the neighboring luminaire is installed). Discovering a neighboring luminaire may mean detecting the presence of the neighboring luminaire in the vicinity of the luminaire and obtaining the address of the neighboring luminaire, of which the presence was detected. That is, the luminaire is configured to discover, using the communication unit, luminaires nearby the luminaire and to measure, using the communication unit, the distance to such nearby luminaires. Herein, an address may be a network address.

[0015] Since the luminaire is configured to store in the data storage for each discovered neighboring luminaire the measured distance in association with the address of the discovered neighboring luminaire, the luminaire can determine, i.e. retrieve, a distance to any luminaire of the discovered neighboring luminaires by receiving the address of the luminaire and using the data storage.

[0016] For example, the luminaire may be configured to discover (e.g. recognize) a neighboring luminaire and store the address of the discovered neighboring luminaire in the data storage. For this, the neighboring luminaire may transmit beacons (e.g. comprising the neighboring luminaire's address) using UWB radio waves (i.e. via UWB radio communication). The luminaire may be configured to measure for a neighboring luminaire, of which the address is stored in the data storage, the distance to the neighboring luminaire and store the measured distance in associated with the already stored address in the data storage.

[0017] Optionally, the luminaire is configured to store, for a discovered neighboring luminaire, the measured distance in association with the address of the discovered neighboring luminaire in a lookup table and / or database.

[0018] By discovering the neighboring luminaires and measuring the distance to the discovered neighboring luminaires the luminaire is configured to locate itself (relatively to the discovered neighboring luminaires) and the neighboring luminaires (relatively to the luminaire) using the UWB radio technology. The luminaire may perform this automatically.

[0019] Optionally, the luminaire may store for a discovered neighboring luminaire, e.g. each discovered neighboring luminaire, additional data such as luminaire type, radio link quality etc.

[0020] The luminaire may comprise three operating states called discovery state, ranging state and standby state.

[0021] The luminaire may be configured to repeatedly, e.g. periodically, perform the discovering step (i.e. discovering neighboring luminaires) and the distance measurement step (e.g. measuring the distance to discovered luminaire(s)). For example, when the luminaire is in the standby state it may repeatedly, e.g. periodically, perform the discovery step. In other words, the luminaire may be configured to repeatedly, e.g. periodically, update the data storage, especially the stored information on the addresses of discovered neighboring luminaires and the associated measured distance to the respective discovered neighboring luminaire. The luminaire may be said to dynamically add and remove the address of discovered neighboring luminaires and the associated measured distance to the respective discovered neighboring luminaire.

[0022] The luminaire may be configured to measure, using the communication unit, the distance to each discovered neighboring luminaire by performing a two way ranging (TWR) measurement.

[0023] This correspond to a ranging state of the luminaire. That is, in the ranging state, the luminaire may measure the distance to each discovered neighboring luminaire. TWR measurement for measuring distance, using UWB radio communication, between two devices, such as two luminaires, is known and, thus, a description of how the TWR measurement is performed is omitted. The TWR measurement method comprises determining the time of flight of UWB radio signals for measuring the distance.

[0024] The luminaire may start the TWR measurement by performing the following steps: The luminaire may transmit a measurement scheduling message to the discovered luminaire. In case the discovered luminaire is available to proceed with the measurement, it transmits a scheduling accept message to the luminaire otherwise it does not respond. The luminaire may wait for a time period (e.g. a dedicated time period) for a response from the discovered luminaire. In case the luminaire does not receive a response from the discovered luminaire it may measure the distance to another discovered luminaire. In case the luminaire receives the scheduling accept message it may perform the TWR measurement process.

[0025] Optionally, the luminaire is configured to delete an address from the data storage in case the discovered neighboring luminaire comprising that address does not respond at least two times in a row during the TWR measurement.

[0026] For example, the luminaire is configured to delete an address from the data storage in case the discovered neighboring luminaire comprising that address does not respond four times in a row during the TWR measurement.

[0027] Optionally, the luminaire is configured to delete an address from the data storage for which a validity time has expired. Preferably, the address is only deleted after executing a new measurement, in case that the luminaire does not respond.

[0028] In other words, each distance measurement stored in the data storage in association to a respective address has a validity time. In case this validity time has expired, the measurement is to be done again and, thus, the address and the associated measured distance are deleted. Deleting an address from the data storage means that a distance measurement stored in association with the address is also deleted. Deleting the address can be performed before the new measurement, or after the measurement only in case of no response.

[0029] The luminaire may be configured to, in response to the luminaire being electrically connected to an electrical power supply or being powered up, discover the neighboring luminaires within the vicinity of the luminaire and store in the data storage the address of each of the discovered neighboring luminaires. For example, the electrical power supply is mains.

[0030] The luminaire may enter a discovery state in response to the luminaire being electrically connected to an electrical power supply, such as mains, or being powered up. After a certain time in the discovery state the luminaire enters a standby state. The luminaire may be configured to discover the neighboring luminaires by searching for beacons using the communication unit, i.e. by sniffing the medium for beacons.

[0031] The luminaire may be configured to, in response to the luminaire being electrically connected to an electrical power supply or being powered up, transmit beacons using the communication unit. For example, the electrical power supply is mains. That is, the luminaire may be configured to broadcast beacons using the communication unit. The luminaire may be configured to repeatedly transmit the beacons using the communication unit. Optionally, the repeatedly transmitting may be a periodical transmission.

[0032] 'The beacons may comprise the luminaire's address. The beacons may be transmitted during the discovery state, which is entered by the luminaire in response to the luminaire being electrically connected to an electrical power supply, such as mains, or being powered up. The luminaire may transmit the beacons for example every 30 ms. After a time period (e.g. dedicated time period), e.g. set by a protocol of a lighting system of which the luminaire may be part, the luminaire may change from the discovery state to the standby state. The beacons may be referred to as "discovery packets" or "discovery beacons".

[0033] The luminaire may be configured to receive, using the communication unit, a message. The message informs on a detection of an object and on an address of a source luminaire that detected the object and initially transmitted the message. The luminaire may be configured to determine, using the data storage and the address of the source luminaire of the received message, a distance to the source luminaire.

[0034] That is, the luminaire may receive (using the communication unit) the message from the source luminaire that detected the object and initially transmitted the message. Since the luminaire received the message using the communication unit and, thus, UWB radio communication, the source luminaire from which the message was received is within a coverage of the UWB radio communication and, thus, is a neighboring luminaire for the luminaire. Therefore, in the data storage of the luminaire, the address of the source luminaire will be stored in association with a distance from the luminaire to the source luminaire. Thus, the luminaire may determine, using the data storage and the address of the source luminaire, the distance to the source luminaire (i.e. the distance between its location to the location of the source luminaire).

[0035] In a standby state, the luminaire may receive one or more messages. Further, in the standby state the luminaire may enter the ranging state. For example, the object may be a person or a vehicle.

[0036] Optionally, the luminaire may be configured to, in response to receiving the message, transmit (using the communication unit) a reply message indicating that the message has been received. The luminaire may be configured to use a reply counter for detecting duplicate message and to prevent reply attacks.

[0037] The luminaire may be configured to use a pre-shared key and symmetric encryption to protect the wireless communication using the communication unit from outside tampering. The luminaire may be configured to use provisioning methods from other protocols (e.g. Bluetooth low energy (BLE)).

[0038] The luminaire may be configured to receive, using the communication unit, a message. The message informs on a detection of an object, an address of a transmission luminaire that transmitted the message, and a distance from the transmission luminaire to a source luminaire that detected the object. The luminaire may be configured to determine, using the data storage, the address of the transmission luminaire and the distance from the transmission luminaire to the source luminaire, a distance to the source luminaire.

[0039] That is, the luminaire may receive (using the communication unit) the message from the transmit luminaire that transmitted the message. Since the luminaire received the message using the communication unit and, thus, UWB radio communication, the transmit luminaire from which the message was received is within a coverage of the UWB radio communication and, thus, is a neighboring luminaire for the luminaire. Therefore, in the data storage of the luminaire, the address of the transmit luminaire will be stored in association with a distance from the luminaire to the transmit luminaire. Thus, the luminaire may determine, using the data storage and the address of the transmit luminaire, the distance to the transmit luminaire. Using the determined distance to the transmit luminaire and the distance from the transmission to the source luminaire, the luminaire may determine the distance to the source luminaire (i.e. the distance between its location to the location of the source luminaire).

[0040] For example, the luminaire may determine the distance to the source luminaire by summing the distance to the transmit luminaire and the distance from the transmit luminaire to the source luminaire.

[0041] The distance from the transmit luminaire to the source luminaire may be referred to as distance field or may be stored in a distance field of the message. In case the message is received from the source luminaire, there is not such distance field in the message.

[0042] Optionally, the luminaire may be configured to, in response to receiving the message, transmit (using the communication unit) a reply message indicating that the message has been received. The luminaire may be configured to use a reply counter for detecting duplicate message and to prevent reply attacks.

[0043] The luminaire may be configured to perform an action depending on the determined distance to the source luminaire.

[0044] For example, the luminaire may be configured to transmit light with a light intensity or a lux level, wherein the greater the determined distance the lower the light intensity or lux level, respectively, and vice versa. The luminaire may be configured to run or perform an algorithm for computing a target intensity or target lux level from the determined distance to the source luminaire. The luminaire may be configured to emit light with the computed target intensity or target lux level. The algorithm may be pre-configured. The algorithm may be configured on runtime. The configuration may comprise threshold values, algorithm parameters and sensor parameters.

[0045] Optionally, the received message informs on additional information. The additional information comprises at least one of a distance between the detected object and the source luminaire, velocity of the detected object and travel direction of the detected object. In addition or alternatively, the additional information comprises information on the environment of the source luminaire. The luminaire may be configured to perform an action depending on the determined distance to the source luminaire and the additional information.

[0046] The information on the environment may be referred to as "context information of the environment". The information on the environment of the luminaire may comprise a temperature, an air quality, ambient light level, etc. For example, the additional information may be used to emit light with a specific characteristic, e.g. fade time.

[0047] The luminaire may be configured to compute a fade time (e.g. fade-up time) of an illumination provided by the luminaire from the distance between the detected object and the source luminaire and the velocity of the detected object. The luminaire may be configured to perform a light emission control by using at least one of the distance between the detected object and the source luminaire, velocity of the detected object and travel direction of the detected object.

[0048] Optionally, the luminaire is configured to ignore the received message in case the determined distance to the source luminaire is greater than a threshold for the distance, or the received message has been received already within a directly previous time period.

[0049] Optionally, the luminaire is configured to forward the received message by generating a message that informs on the detection of the object, the determined distance to the source luminaire and an address of the luminaire, and transmitting, using the communication unit, the generated message.

[0050] That is, the luminaire may forward the received message by including the distance from its location to the source luminaire (i.e. the determined distance to the source luminaire) to the message.

[0051] In case the luminaire received the message from the source luminaire and, thus, the message did not comprise a distance to the source luminaire (i.e. no distance field was included in the message), the luminaire may include a distance field in the message and then forward the message including the distance field. The distance field informs on the determined distance from the luminaire to the source luminaire.

[0052] In case the luminaire received the message from a transmit luminaire (which received from the source luminaire a message informing on the detection of the object) and, thus, the message comprise a distance from the transmit luminaire to the source luminaire (i.e. a distance field was included in the message), the luminaire may update the distance field in the message by determining the distance from the luminaire to the source luminaire using the distance from the luminaire to the transmit luminaire (stored in the data storage) and the distance from the transmit luminaire to the source luminaire (included in the distance field of the received message). Then the luminaire may forward the message comprising the updated distance field. The updated distance field informs on the determined distance from the luminaire to the source luminaire.

[0053] Optionally, the luminaire is configured to not forward the received message in case the determined distance to the source luminaire is greater than a threshold for the distance.

[0054] Optionally, the luminaire comprises a detection unit for detecting an object in a vicinity of the luminaire. The luminaire may be configured to detect, using the detection unit, an object. The luminaire may be configured to, in response to detecting the object, generate and transmit, using the communication unit, a message informing on the detection of the object and on an address of the luminaire that detected the object and initially transmitted the message.

[0055] The detection unit may comprise one or more sensors for detecting the object. The object may be for example a person, a vehicle (e.g. car, bicycle) etc. The detection unit may comprise one or more sensors. For example, the detection unit may comprise one or more of the following sensors: one or more presence- and / or movements sensors (e.g. one or more passive infrared (PIR) sensors) configured to detect a presence and / or movement of the object, such as a person or vehicle; one or more sensors, optionally radar based sensors, for measuring a distance to the object; one or more audio sensors (e.g. one or more microphones) for detecting a typical sound of the object, such as a human voice of a person, a driving sound of a vehicle etc.; one or more sensors for measuring a temperature of the object; one or more light detecting and ranging (LIDAR) sensors, one or more cameras, and one or more video cameras. Optionally, the detection unit may comprise one or more sensors (e.g. one or more microphones) for detecting a voice of a person and the detection unit may be configured to detect voice commands. The term "detection module" may be used as a synonym for the term 2detection unit".

[0056] The vicinity of the luminaire, where the detection unit may be configured to detect the object, may correspond or comprise to an area that can be illuminated by the luminaire. In other words, the detection unit may be configured to detect an object, such as a person or vehicle, in an environment of the luminaire.

[0057] In the standby state, the luminaire may detect an object in its vicinity. Since the luminaire detected the object and initially transmitted the message, the luminaire may be referred to as "source luminaire" and the address of the luminaire may be referred to as "address of the source luminaire".

[0058] The luminaire may be configured to repeatedly transmit the message. Such repeated transfers allow confirming the message delivery.

[0059] The luminaire may be configured to use a pre-shared key and symmetric encryption to protect the wireless communication using the communication unit from outside tampering. The luminaire may be configured to use provisioning methods from other protocols (e.g. Bluetooth low energy (BLE)).

[0060] Optionally, the luminaire is configured to generate the message such that the message informs on additional information. The additional information comprises at least one of a distance between the detected object and the luminaire, velocity of the detected object and travel direction of the detected object. In addition or alternatively the additional information comprises information on the environment of the luminaire.

[0061] The information on the environment of the luminaire may comprise a temperature, an air quality, etc. The luminaire may be configured to obtain the additional information by performing measurements and / or receiving the additional information. For example, the luminaire may be configured to measure the distance between the detected object and the luminaire and / or receive that information from outside, e.g. from the detected object. The luminaire may be configured to measure the velocity of the detected object and / or receive the velocity of the detected object from outside, e.g. from the detected object. The luminaire may be configured to determine a travel direction of the detected object and / or receive the travel direction from outside, e.g. from the detected object. The luminaire may be configured to measure the information on the environment of the luminaire, e.g. by measuring temperature, air quality and / or one or more other characteristics of the environment. In addition or alternatively, the luminaire may be configured to obtain the information on the environment from outside, e.g. from one or more external sensors.

[0062] In the standby state, the luminaire may repeatedly transmit the beacons with a lower frequency compared to the ranging state. In the standby state, the luminaire may search for beacons using the communication unit, i.e. by sniffing the medium for beacons.

[0063] The luminaire may be configured to repeatedly transmit, using the communication unit, beacons with a frequency. The frequency may be greater during a time period starting with the luminaire being electrically connected to an electrical power supply, such as mains, or being powered up.

[0064] In the standby state, the luminaire may repeatedly transmit the beacons with a lower frequency compared to the ranging state. That is, the luminaire may be configured to broadcast beacons using the communication unit. Optionally, the repeatedly transmitting may be a periodical transmission.

[0065] In order to achieve the luminaire according to the first aspect of the present invention, some or all of the above-described optional features may be combined with each other.

[0066] According to a second aspect of the invention a luminaire is provided. The luminaire comprises a communication unit for an ultra-wideband (UWB) radio communication, and a detection unit for detecting an object in a vicinity of the luminaire. The luminaire is configured to detect, using the detection unit, an object. The luminaire is configured to, in response to detecting the object, generate and transmit, using the communication unit, a message informing on the detection of the object and on an address of the luminaire that detected the object and initially transmitted the message.

[0067] Since the luminaire detected the object and initially transmitted the message, the luminaire may be referred to as "source luminaire" and the address of the luminaire may be referred to as "address of the source luminaire".

[0068] The description of the luminaire of the first aspect is correspondingly valid for the luminaire of the second aspect.

[0069] The detection unit may comprise one or more sensors for detecting the object. The object may be for example a person, a vehicle (e.g. car, bicycle) etc. The detection unit may comprise one or more sensors. For example, the detection unit may comprise one or more of the following sensors: one or more presence- and / or movements sensors (e.g. one or more passive infrared (PIR) sensors) configured to detect a presence and / or movement of the object, such as a person or vehicle; one or more sensors, optionally radar based sensors, for measuring a distance to the object; one or more audio sensors (e.g. one or more microphones) for detecting a typical sound of the object, such as a human voice of a person, a driving sound of a vehicle etc.; one or more sensors for measuring a temperature of the object; one or more light detecting and ranging (LIDAR) sensors, one or more cameras, and one or more video cameras. Optionally, the detection unit may comprise one or more sensors (e.g. one or more microphones) for detecting a voice of a person and the detection unit may be configured to detect voice commands.

[0070] The vicinity of the luminaire, where the detection unit may be configured to detect the object, may correspond or comprise to an area that can be illuminated by the luminaire. In other words, the detection unit may be configured to detect an object, such as a person or vehicle, in an environment of the luminaire.

[0071] The luminaire may be configured to repeatedly transmit the message. Such repeated transfers allow confirming the message delivery.

[0072] The luminaire may be configured to use a pre-shared key and symmetric encryption to protect the wireless communication using the communication unit from outside tampering. The luminaire may be configured to use provisioning methods from other protocols (e.g. Bluetooth low energy (BLE)).

[0073] Optionally, the luminaire is configured to generate the message such that the message informs on additional information. The additional information comprises at least one of a distance between the detected object and the luminaire, velocity of the detected object and travel direction of the detected object. In addition or alternatively the additional information comprises information on the environment of the luminaire.

[0074] The information on the environment of the luminaire may comprise a temperature, an air quality, etc.).

[0075] The luminaire may be configured to obtain the additional information by performing measurements and / or receiving the additional information. For example, the luminaire may be configured to measure the distance between the detected object and the luminaire and / or receive that information from outside, e.g. from the detected object. The luminaire may be configured to measure the velocity of the detected object and / or receive the velocity of the detected object from outside, e.g. from the detected object. The luminaire may be configured to determine a travel direction of the detected object and / or receive the travel direction from outside, e.g. from the detected object. The luminaire may be configured to measure the information on the environment of the luminaire, e.g. by measuring temperature, air quality and / or one or more other characteristics of the environment. In addition or alternatively, the luminaire may be configured to obtain the information on the environment from outside, e.g. one or more external sensors.

[0076] The description of the luminaire according to the first aspect may be correspondingly valid for the luminaire according to the second aspect. The description of the luminaire according to the second aspect may be correspondingly valid for the luminaire according to the first aspect.

[0077] The luminaire according to the second aspect achieves the same advantages as the luminaire according to the first aspect.

[0078] In order to achieve the luminaire according to the second aspect of the present invention, some or all of the above-described optional features may be combined with each other.

[0079] According to a third aspect of the invention a system is provided. The system comprises a luminaire according to the first aspect of the invention, as described above, and a luminaire according to the second aspect of the invention as described above.

[0080] The system may be a swarm control lighting system.

[0081] The luminaire of the second aspect may be implemented in line with the features of the luminaire according to the first aspect. The description of the luminaire according to the first aspect may be correspondingly valid for the luminaire according to the second aspect.

[0082] The system according to the third aspect achieves the same advantages as the luminaire according to the first aspect.

[0083] All steps which are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities.

[0084] In the following, the invention is described exemplarily with reference to the enclosed figures (FIGs.), in which FIG. 1 shows an example of a luminaire according to an embodiment of the present invention. FIG. 2 shows an example of a luminaire according to an embodiment of the present invention. FIG. 3 shows an example of an implementation form of the luminaire of FIG. 1. FIG. 4 shows a block diagram showing an example of different operation states of the luminaire of FIG. 3. FIG. 5 shows a scenario, in which multiple luminaires of FIG. 3 are used for providing illumination to an area. FIG. 6 shows the scenario of FIG. 5, in case a luminaire of the multiple luminaires detects an object. FIG. 7 shows an example of illumination by multiple luminaires according to FIG. 3 in case one of the multiple luminaires detects an object. FIG. 8 shows an example of illumination by multiple luminaires according to FIG. 3 in case one of the multiple luminaires detects a moving object. FIGs. 9 (a), 9 (b), 9 (c) and 9 (d) show different steps of three luminaires according to an embodiment of the invention, such as the lumi-naires of FIG. 1 or FIG. 3. FIGs. 10, 11 and 12 show a flow diagram of an example of an operation of a luminaire accord-ing to an embodiment of the invention, such as such as the lumi-naire of FIG. 1 or FIG. 3.

[0085] In the FIGs., corresponding elements have the same reference signs. The proportions and dimensions of the elements shown in the FIGs. do not represent the respective luminaire to scale, but are merely chosen to describe the structure and function of the respective luminaire.

[0086] FIG. 1 shows an example of a luminaire according to an embodiment of the present invention. The luminaire of FIG. 1 is an example of the luminaire of the first aspect. The description of the luminaire of the first aspect is correspondingly valid for the luminaire of FIG. 1.

[0087] The luminaire 1 of FIG. 1 comprises a communication unit 2 for an ultra-wideband (UWB) radio communication, and a data storage 3. The luminaire 1 is configured to discover, using the communication unit 2, neighboring luminaires within a vicinity of the luminaire 1. The luminaire 1 is configured to measure, using the communication unit 2, a distance to each discovered neighboring luminaire. The luminaire 1 is configured to store in the data storage 2 for each discovered neighboring luminaire the measured distance in association with an address of the discovered neighboring luminaire.

[0088] For further details on the luminaire of FIG. 1, reference is made to the description of the luminaire of the first aspect and the description of FIGs. 3 to 12.

[0089] FIG. 2 shows an example of a luminaire according to an embodiment of the present invention. The luminaire of FIG. 2 is an example of the luminaire of the second aspect. The description of the luminaire of the second aspect is correspondingly valid for the luminaire of FIG. 2.

[0090] The luminaire 1' of FIG. 2 comprises a communication unit 2 for an ultra-wideband (UWB) radio communication, and a detection unit 4 for detecting an object (e.g. a person or a vehicle) in a vicinity of the luminaire 1'. The luminaire 1' is configured to detect, using the detection unit 4, an object. The luminaire 1' is configured to, in response to detecting the object, generate and transmit, using the communication unit 2, a message informing on the detection of the object and on an address of the luminaire 1' that detected the object and initially transmitted the message.

[0091] FIG. 3 shows an example of an implementation form of the luminaire of FIG. 1. The description of FIG. 1 is correspondingly valid for the luminaire 1 of FIG. 3.

[0092] The luminaire 1 of FIG. 3 may comprise in addition to the communication unit 2 for UWB radio communication and the data storage 3, a detection unit 4 for detecting an object (e.g. a person or a vehicle) in a vicinity of the luminaire 1. For example, the detection unit 4 may comprise or correspond to one or more presence and / or movement sensors. The detection unit 4 may be differently implemented.

[0093] The data storage 3 may comprise a RAM and / or a flash memory. Further, the luminaire 1 may comprise as its light source 8 one or more LEDs and a LED driver 7 for electrically supplying and, thus, driving the one or more LEDs 8. This is only an example of a possible light source 8 of the luminaire 1 and, thus, does not limit the present invention. Therefore, the description of FIG. 3 is correspondingly valid in case of another light source 8. The luminaire may comprise an ambient light sensor 5. Further, the luminaire 1 may comprise a control unit 6 for controlling the operation of the luminaire 1 and, thus, the components of the luminaire 1. As indicated in FIG. 3, the control unit 1 may control the LED driver 7 in order to control a light emission by the one or more LEDs 8. The control unit 1 may communicate via the UWB radio communication unit 2. The control unit 1 may receive a message in the form of UWB radio waves via the communication unit 2 and control operation of the luminaire 1 based on the received message. For example, the control unit 1 may control light emission by the one or more LEDs 8 based on information included in the received message. The control unit 1 may transmit a message in the form of UWB radio waves to neighboring luminaires (i.e. luminaires within the range of the UWB radio communication) via the communication unit 2. For example, in response to the detection unit 4 detecting an object (such as a person or vehicle) in the vicinity of the luminaire 1, the control unit 1 may transmit a message via the communication unit 2, wherein the message informs on the detection of the object and on an address of the luminaire 1 (being a source luminaire that detected the object and initially transmitted the message). For this, the control unit 1 may obtain detection results of the detection unit 4, as shown in FIG. 3. Furthermore, the control unit 1 may perform a discovery of neighboring luminaires (i.e. luminaires in the range of the UWB radio communication) and a distance measurement from the luminaire 1 to the discovered neighboring luminaires using the communication module 2.

[0094] The control unit 1 may obtain detection results of the ambient light sensor 5 in order to obtain information on the ambient light level. The control unit 1 may use this information for controlling the light emission of the luminaire 1. The control unit 1 may store information in the data storage 3 (i.e. write data to the data storage 3) and retrieve information from the data storage 3 (i.e. read information from the data storage 3). For example, the control unit 1 may store the addresses of discovered neighboring luminaires in the data storage 3 in association with a measured distance to the respective luminaire of the discovered neighboring luminaires.

[0095] The control unit 1 may comprise or may be at least one of a controller, microcontroller, processor, microprocessor, application specific integrated circuit (ASIC) and field programmable gate array (FPGA). The control unit 1 may comprise or may be a central control unit (CPU). The control unit 1 is not limited to a specific type of control unit.

[0096] As outlined above, the luminaire 1 may use UWB radio communication for distance measurement and wireless communication.

[0097] For describing an example of operation of the luminaire 1 of FIG. 3, reference is made to FIG. 4.

[0098] FIG. 4 shows a block diagram showing an example of different operation states of the luminaire of FIG. 3. As shown in FIG. 4, there may be three operation states comprising a discovery state, a ranging state and a standby state. Optionally, there may be a boot state. The boot state is triggered when the luminaire 1 is electrically connected to an electrical power supply, such as mains, or is powered up. After the boot state, the luminaire 1 may enter the discovery state. In the discovery state, the luminaire 1 may discover, using the communication unit 2, neighboring luminaires in the vicinity of the luminaire 1, i.e. within a coverage of the UWB radio communication. For this, the neighboring luminaires may broadcast beacons comprising the address of the respective neighboring luminaire. The luminaire 1 may store the address of each luminaire of the discovered neighboring luminaires in the data storage 3. During the discovery state, the luminaire 1 may broadcast, using the communication unit 2, beacons comprising the luminaire's address. This allows the luminaire 1 to be discovered by other luminaires, e.g. the neighboring luminaire. In the discovery state, the luminaire 1 may broadcast the beacons with a frequency of e.g. 30 ms. After a discovery time (i.e. time during which the discovery state is to be performed) has passed since the boot, the luminaire may enter the standby state.

[0099] In the standby state, the luminaire is ready to start the distance measurement, using the communication unit, with regard to each discovered neighboring luminaire 1 for which the address is stored in the data storage. In the standby state, the luminaire 1 may detect, using the detection unit 4, an object (e.g. a person or vehicle) in the vicinity of the luminaire 1 and, in response to detecting an object, transmit a message to the neighboring luminaires using the communication unit 2, wherein the message informs on the detection of the object and on the address of the luminaire 1. Optionally, the luminaire may 1 emit light, e.g. with a maximum light intensity or maximum lux level, in response to detecting the object. In the standby state, the luminaire 1 may receive, using the communication unit 2, a message that informs on a detection of an object, an address of another luminaire and optionally a distance field. The other luminaire may be a source luminaire that detected the object and initially transmitted the message received by the luminaire 1. In this case, there is no distance field in the received message. The other luminaire may be a transmit luminaire that forwarded the received message. In this case, the optional distance field is present in the received message and comprises or informs on the distance from the transmit luminaire to the source luminaire.

[0100] The luminaire 1 may determine the distance to the source luminaire (that detected the object and initially transmitted the received message) using the information of the data storage 3 and the information of the message. In particular, the address of the received message is used to retrieve from the data storage the distance that is stored in the data storage in association with the address of the received message. In case no distance field is present in the received message, the distance obtained from the data storage using the address of the received message is the distance from the luminaire 1 to the source luminaire. Otherwise, i.e. the distance filed is present in the received message, the distance from the luminaire 1 to the source luminaire equals to the sum of the distance obtained from the data storage using the address of the received message and the distance of the distance field of the received message.

[0101] The luminaire 1 may perform an action depend on the determined distance from the luminaire 1 to the source luminaire. For example, the luminaire 1 may emit light with a light intensity or lux level that depends on the determined distance. Optionally, the greater the determined distance the lower the light intensity or lux level and vice versa. For example, the luminaire may input the determined distance to a mathematical formula to compute a target light intensity or target lux level and emit light with the computed target light intensity or target lux level. In case, the computed target light intensity or target lux level is lower than a light intensity or lux level, respectively, of the ambient light around the luminaire 1, then the luminaire may not perform an action, e.g. does not emit light.

[0102] In the standby state, the luminaire 1 may search for beacons in order to discover new neighboring luminaires, i.e. neighboring luminaires of which the address is not stored in the data storage 3. In the standby state, the luminaire 1 may broadcast, using the communication unit 2, beacons comprising the luminaire's address. In the standby state, the luminaire 1 may broadcast the beacons with a frequency that is smaller than the frequency for broadcasting beacons in the discovery state. That is, in the standby state the luminaire 1 may broadcast beacons less frequently compared to the discovery state.

[0103] In case a validity time of an entry of entries of the data storage, each entry comprising the address of a neighboring luminaire and a distance from the luminaire 1 to the neighboring luminaire, expires, the luminaire may enter the ranging state. The luminaire 1 may enter the ranging state after the discovery state in order to measure the distance for each neighboring luminaire that was discovered during the discovery state. The measurement of the distance to a neighboring luminaire for which the address is stored in the data storage 3 may be done using a two way ranging (TWR) measurement. The measured distance from the luminaire 1 to the neighboring luminaire is then stored in association with the already stored address of the neighboring luminaire. In case during the TWR measurement a neighboring luminaire does not respond at least two times, optionally for times, in a row, the luminaire 2 may remove the address of the neighboring luminaire from the data storage 3. Each distance measurement (stored in association with the address of the respective neighboring luminaire) may have a validity time, after which the measurement is to be done again.

[0104] For further information on an operation of the luminaire, reference is made to the following FIGs. 5 to 12.

[0105] FIG. 5 shows a scenario, in which multiple luminaires of FIG. 3 are used for providing illumination to an area.

[0106] In the example of FIG. 5, it is assumed that multiple luminaires 1 of FIG. 3 are installed in an area. In this area some luminaires 1 of the multiple luminaires 1 are arranged in a room such that a signal strength of the UWB radio communication is too weak to communicate with outside the room. This is indicated by the dashed line L1 in FIG. 5. In FIG. 5, the double arrows between the luminaires 1 indicate for each luminaire 1 of the multiple luminaires 1 a possible UWB radio communication to one or more other luminaires, which are thus the neighboring luminaires of the luminaire that may be discovered by the luminaire.

[0107] Each luminaire 1 of the multiple luminaires 1 may discover, using UWB radio communication, its neighboring luminaires and measure, using UWB radio communication, the distance to each of the discovered neighboring luminaires. This may be done with a predefined interval. In case a luminaire 1 of the multiple luminaires 1 is removed, the other luminaires that were able to discover (e.g. reach) the removed luminaire may detect this removal and thus may update their data storage by removing the address of the removed luminaire from the data storage.

[0108] FIG. 6 shows the scenario of FIG. 5, in case a luminaire of the multiple luminaires detects an object. As shown in FIG. 6, a person (as an example of an object) may be detected by a luminaire 1a of the multiple luminaires 1, which may be referred to as source luminaire 1a. In response to the luminaire 1a detecting the person, it transmits, using UWB radio communication, a message to the neighboring luminaires of the multiple luminaires 1, i.e. to the luminaires that are in the range of the UWB radio communication unit and, thus, were able to discover and measure, using UWB radio communication, the source luminaire 1a. This is indicated by the solid arrows, wherein the longer a solid arrow the greater the distance between the source luminaire 1a to the neighboring luminaire to which the solid arrow points to. The dashed arrow indicates a luminaire of the multiple luminaires 1 that is located too far away such that it is outside the range of UWB radio communication and, thus, the message transmitted, using the UWB radio communication, from the source luminaire 1a cannot reach it.

[0109] Each of the neighboring luminaires may receive the message and may determine a distance to the source luminaire 1a as outlined above, e.g. in the description of FIG. 4. Each of the neighboring luminaires may compute a target light level or target lux level using the determined distance from the neighboring luminaire to the source luminaire 1a. As indicated in FIG. 6, the greater the distance (i.e. the longer the respective solid arrow), the lower the computed target light intensity or target lux level (i.e. the lower the density of points in the circle representing the respective luminaire). If a current light intensity or lux level of the ambient light at a neighboring luminaire is greater than the computed target light intensity or target lux level, the neighboring luminaire does not emit light.

[0110] FIG. 7 shows an example of illumination by multiple luminaires according to FIG. 3 in case one of the multiple luminaires detects an object.

[0111] As shown in FIG. 7, a source luminaire 1a of the multiple luminaires 1 detects the person (being an example of an object). The description of FIG. 7 is correspondingly valid in case of a different type of object. As a result, the source luminaire 1a emits light (e.g. at its maximum light intensity or a pre-set light intensity e.g. set by a configuration of the luminaires) to provide illumination for the person. In addition, the source luminaire 1a transmits, using its UWB radio communication unit, a message to its neighboring luminaires 1b, wherein the message informs on the detection of the person and the address of the source luminaire 1a. Thus, each luminaire 1b of the neighboring luminaires 1b receives said message and determines, using its data storage and the address of the source luminaire 1a included in the received message, the distance from its location to the location of the source luminaire 1a. For each of the neighboring luminaires 1b of the source luminaire 1a, the source luminaire 1a itself is a neighboring luminaire. Therefore, each of the neighboring luminaires 1b of the source luminaire 1a stores in its data storage an entry comprising the address of the source luminaire 1a (e.g. obtained in the discovery state) in association with the distance to the source luminaire 1a (e.g. measured in the ranging state). Thus, each neighboring luminaire 1b of the source luminaire 1a can determine the distance to the source luminaire 1a by reading the distance stored in association with the address of the source luminaire 1a from the data storage. Each neighboring luminaire 1b then computes a target light intensity at which it emits light in response to the received message informing about the detected person. For this, the neighboring luminaire 1b may input the determined distance to the source luminaire 1a into a mathematic equation. For example, the mathematical equation may describe a linear relationship between the light intensity and the distance from the neighboring luminaire 1b to the source luminaire 1a, wherein the greater the distance the lower the light intensity and vice versa, as shown on the left side of FIG. 7. This is only by way of example and, thus, a different relationship between the distance and light intensity may be used for computing the target light intensity. Instead of the target light intensity, a target lux level of the light emission may be computed. The description of FIG. 7 is correspondingly valid. The neighboring luminaires 1b may then emit light with the computed target light intensity.

[0112] Optionally, the neighboring luminaires 1b may detect the ambient light intensity and emit the light at the target light intensity only in case the target light intensity is greater than the light intensity of the ambient light; otherwise the neighboring luminaires 1b may not emit light. This allows saving energy. In the example of FIG. 7, it is assumed that the neighboring luminaires 1b of the source luminaire 1a are located 5 m away from the source luminaire 1a, i.e. the distance between a neighboring luminaire 1b to the source luminaire 1a is 5 m. Since the target light intensity is computed in the luminaires 1 according to the mathematical formula, luminaires that have a same distance (e.g. 5 m or 10 m) to the source luminaire 1a emit light at the same target light intensity. This allows a homogenously changing light intensity in an area around the source luminaire 1a.

[0113] As shown in FIG. 7, each neighboring luminaire 1b of the source luminaire 1a forwards the message received from the source luminaire 1a to its neighboring luminaires 1c. For this, each neighboring luminaire 1b of the source luminaire 1a includes a distance field in the message and changes the address field of the message to comprise its address (instead of the address of the source luminaire 1a) before forwarding the message, wherein the distance field comprises the distance between itself and the source luminaire 1a. Thus, the neighboring luminaires 1b of the source luminaire 1a forwarding the received message act as transmit luminaires for their neighboring luminaires 1c. Therefore, the forwarded message informs on the detected person, the distance from the neighboring luminaire 1b of the source luminaire 1a to the source luminaire 1a and the address of the neighboring luminaire 1b of the source luminaire 1a. The source luminaire 1a may also receive this forwarded message. However, since the message informs on detection of the object by the source luminaire 1a, the source luminaire 1a ignores this message and does not act as a neighboring luminaire in response to said forwarded message.

[0114] Each of the luminaires 1c receiving the forwarded message from the neighboring luminaires 1b of the source luminaire 1a, may determine a distance from itself to the source luminaire 1a. For this, the luminaire 1c uses its data storage as well as the address of the luminaire 1b and the distance from the luminaire 1b to the source luminaire 1a of the received message. For the luminaire 1c, the luminaire 1b (from which the forwarded message is received) is a neighboring luminaire. Therefore, the luminaires 1c stores in its data storage an entry comprising the address of the luminaire 1b (e.g. obtained in the discovery state) in association with the distance to the luminaire 1b (e.g. measured in the ranging state). Thus, each luminaire 1c can determine the distance to the luminaire 1b by reading the distance stored in association with the address of the luminaire 1b from the data storage. The luminaire 1c determines the distance to the source luminaire 1a by summing the distance to the luminaire 1b (determined using the data storage and the address of the forwarded message) and the distance of the distance field of the forwarded message (being the distance from the luminaire 1b to the source luminaire 1a). Each luminaire 1c then computes a target light intensity at which it emits light in response to the received message informing about the detected person, as outlined above with regard to the neighboring luminaires 1b of the source luminaire 1a. Since the distance to the source luminaire 1a determined by the luminaires 1c (which is assumed to be e.g. 10 m in the example of FIG. 7) is greater than the distance to the source luminaires 1a determined by luminaires 1b, the light emitted by the luminaires 1c has a lower light intensity compared to the light emitted by the luminaires 1b. Thus, the luminaires 1 of FIG. 7 allow to provide an illumination in an area where a person is present, wherein the light intensity may decrease the further away from the person. This allows fluidly fading the light intensity without steps.

[0115] Each of the luminaires 1 does not forward the received message in case the determined distance to the source luminaire 1a is greater than a threshold for the distance. In the scenario of FIG. 7, it is exemplarily assumed that the threshold for the distance is 8 m. As a result, the luminaires 1c will not forward the received message, as they are located 10 m away from the source luminaire 1a. This allows setting an area, especially boundaries of such an area, in which the detection of a person may trigger an illumination with a fading light intensity the further away from the person.

[0116] Moreover, the luminaires 1 may ignore a received message in case the determined distance to the source luminaire 1a is greater than a threshold for the distance or the received message has been received already within a directly previous time period. The threshold for the distance mentioned with regard to ignoring the message and the threshold for the distance mentioned above with regard to forwarding the message may be different. For example, assuming that the threshold for the distance with regard to forwarding the message and with regard to ignoring the message is 12 m, the luminaires 1c would forward the message informing on the person detected by the source luminaire 1a, as described for the luminaires 1b above. In case luminaires that are located 14 m away from the source luminaire 1a (such luminaires are not shown in FIG. 7) receive the forwarded message, they would ignore the message and, thus, not trigger a light emission because their distance to the source luminaire 1a is greater than the threshold for the distance being 12 m. Furthermore, when the luminaires 1c would forward the message, the neighboring luminaires 1b of the source luminaire 1a may receive a message informing about the detected person again. As a result, the neighboring luminaires 1b of the source luminaire 1a ignore said message received from the luminaires 1c as said message has been received already within a directly previous time period.

[0117] The luminaires 1 may be indoor luminaires or outdoor luminaires.

[0118] FIG. 8 shows an example of illumination by multiple luminaires according to FIG. 3 in case one of the multiple luminaires detects a moving object. In the example of FIG. 8, the moving object is assumed to be a moving car. The description of FIG. 8 is correspondingly valid in case of a different type of object. In FIG. 8, the density of points in the circle representing a luminaire indicates the light intensity of the light emitted by the luminaire, wherein the greater the density of points the greater the light intensity. As described already with regard to FIG 7, a source luminaire 1a (being the luminaire L1) may detect the object, i.e. the moving vehicle, and transmit a message informing about the detection to its neighboring luminaire 1b (luminaire L2), which then may forward the message to a further luminaire (luminaire L3). In response to the detection, the source luminaire L1 may emit light and in response to receiving the message informing on the detection of the vehicle the other luminaires L2 and L3 may emit light with a reduced light intensity, wherein the further away the luminaire from the source luminaire L1 the lower the light intensity. For a detailed description of this process, reference is made to the description of FIG. 7. In the following, mainly an additional optional feature of the luminaires 1 is described.

[0119] When a luminaire 1, such as the luminaire L1, detects the presence of the vehicle, it may measure at least one of a distance to the detected vehicle, velocity of the detected vehicle and travel direction of the detected vehicle. In addition or alternatively, the luminaire L1 may receive said information from outside, e.g. from the detected vehicle. The luminaire L1 may add the aforementioned information as additional information to the message that informs on the detected vehicle and is transmitted by the luminaire L1 in response to detecting the vehicle.

[0120] Each luminaire (e.g. luminaire L2 and L3 in the example of FIG. 8) receiving the message informing on the detection of the presence of the vehicle, may use the additional information in addition to the determined distance to the source luminaire 1a (i.e. luminaire L1) for computing a target light intensity and optionally a fade-up time. For example, the luminaire L2 and L3 may each compute the target light intensity and optional a fade-up time using the determined distance to the source luminaire L1 and at least one of the distance between the source luminaire L1 to the detected vehicle, the velocity of the detected vehicle and the travel direction of the detected vehicle, optional all of the aforementioned three parameters of the message.

[0121] Optionally, in case the message received by the luminaire L2 or L3 comprises the velocity of the detected vehicle, the luminaire L2 or L3, respectively, may compute an arrival time of the vehicle at its location using an algorithm and use the computed arrival time for configuring a fade-up time of its light emission. In the example of FIG. 8, the luminaire L3 is assumed to be located a distance away from the source luminaire L1 that is greater than the threshold for the distance with regard to forwarding the message and thus the luminaire L3 does not forward the message to the luminaire L4.

[0122] Optionally, the luminaires may be configured to ignore a received message depending on the determined distance to the source luminaire and a velocity included in the message.

[0123] FIGs. 9 (a), 9 (b), 9 (c) and 9 (d)show different steps of three luminaires according to an embodiment of the invention, such as the luminaires of FIG. 1 or FIG. 3.

[0124] FIG. 9 (a) shows a state in which the luminaires L1 and L2 are powered up or electrically connected to an electrical power supply and, thus, are in the discovery state. As a result, the luminaires L1 and L2 both repeatedly transmit beacons comprising its address and discover neighboring luminaires (e.g. searching or sniffing the medium for beacons of other luminaires).

[0125] Therefore, luminaire L1 receives the beacons from luminaire L2 and, thus, stores the address ADL2 of the discovered neighboring luminaire L2. The table "L1" indicates the data storage, e.g. a lookup table in the data storage, of the luminaire L1. Luminaire L2 receives the beacons from luminaire L1 and, thus, stores the address ADL1 of the discovered neighboring luminaire L1.

[0126] The table "L2" indicates the data storage, e.g. a lookup table in the data storage, of the luminaire L2. In the states of FIGs. 9 (a), 9 (b) and 9 (c) it is assumed that the luminaire L3 is not powered up or not connected to an electrical power supply.

[0127] FIG. 9 (b) shows a state in which the luminaires L1 and L2 are in the standby state. In the standby state, the luminaires L1 and L2 are ready to start the distance measurement for the addresses stored in the data storage. This allows them to react in case of detecting presence of an object or receiving a message from another luminaire that informs on a detected object. The luminaires L1 and L2 may still emit beacons and search the medium for other luminaires in the standby state, however less frequently compared to the discovery state.

[0128] FIG. 9 (c) shows a state in which the luminaire L1 is assumed to be in a ranging state. That is, luminaire L1 measures the distance to the luminaire L2 of which luminaire L1 stores the address ADL2 in its data storage. For this, the luminaire L1 may perform a TWR measurement. Therefore, the luminaire L1 tries to schedule a TWR measurement with the luminaire L2 to measure the distance between them. The scheduling process may work as follows: The luminaire L1 transmits a measurement scheduling message (MSM) to the luminaire L2. In case the luminaire L2 is available to proceed with the TWR measurement, it transmits a scheduling accepted message (MAM). Otherwise, luminaire L2 does not respond. The luminaire L1 may wait for a period of time for the response from the luminaire L2. If no message is received, it returns to the standby state, and after a delay period, the luminaire L1 may try to measure another luminaire of which the address is stored in the data storage. If the luminaire L2 doesn't respond e.g. four times in a row it will be considered out of range and, thus, the luminaire L1 deletes the address ADL2 of the luminaire L2 and, thus, the entry of the luminaire L2 from its data storage. If the luminaire L1 receives a scheduling accepted message (SAM) from the luminaire L2, they will enter the TWR measurement process. After the luminaire L1 has measured the distance to the luminaire L2, it may store in its data storage the distance in association with the address ADL2 of the luminaire L2.

[0129] Figure 9 (d) shows a state, in which the luminaries L1 and L2 participate in the TWR measurement process and the luminaire L3 is powered up or electrically connected to an electrical power supply and, thus, enters the discovery state.

[0130] Therefore, the luminaires L1 and L2 may store the measured distance D1 between them in association with the address ADL2 of the luminaire L2 or the address ADL1 of the luminaire L1, respectively. In addition, a validity time T1 may be stored with the measured distance D1. After this validity time T1 the distance measurement is to be repeated. The validity time may be computed by taking the timestamp of the moment the distance measurement was taken and incrementing a fixed validity time, e.g. at least 30 minutes.

[0131] The luminaire L3 being in the discovery state may listen to the messages exchanged between the luminaires L1 and L2 during the TWR measurement and, thus, may discovery these two luminaires L1 and L2 as neighboring luminaires. As a result, the luminaire L3 stores the addresses ADL1 and ADL2 of the luminaire L1 and L2, respectively, in its data storage, e.g. in a lookup table.

[0132] FIGs. 10, 11 and 12 show a flow diagram of an example of an operation of a luminaire according to an embodiment of the invention, such as the luminaire of FIG. 1 or FIG. 3.

[0133] As shown FIG. 10, the process may start when the luminaire is powered up or electrically connected to an electrical energy supply. As a result, the luminaire will transmit in the discovery state beacons, which may be referred to as discovery beacons (step S1 of FIG. 10). Next, the luminaire may check in a step S2 whether a message, such as a beacon, is received from another luminaire. In case this is true (yes at step S2), the luminaire may check whether the address of the other luminaire (from which the message (e.g. beacon) was received) is already stored in the data storage (cf. step S3). In case the address is not stored already, the address of the other luminaire is stored in the data storage (i.e. the device is added to the data storage). The luminaire may continue to stay in the discovery state after that storing (i.e. step S3 proceeds to step S1). In case no message (e.g. beacon) is received by the luminaire (no at step S2), the luminaire may determine whether a discovery time has passed, i.e. whether the discovery state is to be ended or not (cf. step S4). In case the discovery time is not passed yet (i.e. the discovery state is not to be ended, i.e. no at step S4), the luminaire stays in the discovery state, i.e. the step S4 proceeds to step S1. Otherwise (yes at step S4), the luminaire will enter the standby state.

[0134] In the standby state the luminaire may check, whether it has received a message (cf. step S5). In case no message is received (no at step S5), the luminaire may check, whether it has detected an object in its vicinity (cf. step S6). In case no object is detected (no at step S6), the luminaire may check whether there is a distance to measure for a device (i.e. luminaire) of which the address is stored in the data storage (cf. step S7). In case there is not distance to measure (i.e. no at step S7), the luminaire may transmit a periodic beacon (cf. step S8) and return to step S5.

[0135] In case at step S5 the luminaire receives a message, such as a beacon, from another luminaire (i.e. yes at step S5), the luminaire may check whether the address of the other luminaire (from which the message (e.g. beacon) was received) is already stored in the data storage (cf. step S9). In case the address is not stored already, the address of the other luminaire is stored in the data storage (i.e. the device is added to the data storage). Next in a step S10, the luminaire may check whether a TWR message request message has been received. In case no such message is received (no at step S10), the luminaire checks in step S11 whether a presence detected message is received. In case no presence detected message is received (no at step S11), the luminaire returns to step S5.

[0136] In case a TWR request message is received (yes at step S10), the process continues with the step S17 shown in FIG. 11. In the step S17, the luminaire transmits a reflector response message. Next in a step S14, a TWR measurement is performed between the luminaire and the luminaire from which the TWR request message was received in step S10. Next, the luminaire checks in step S15 whether the TWR measurement was successful. In case it was successful (yes at step S15), the luminaire stores, in its data storage, the measured distance in association with the address of the luminaire from which the TWR request message was received in step S10 (cf. step S16). The step S16 proceeds to step S5 shown in FIG. 10. In case the TWR measurement was not successful (no at step S15), the luminaire may decrement in a step S18 a timeout counter. This time counter may initially be set to four, which is only by way of example. In a next step S19, the luminaire may check whether the timeout counter equals zero. In case this is true (yes at step S19), the address of the other luminaire, to which the luminaire tried to measure the distance, is removed from the data storage and then the process continues at step S5 of FIG. 10. In case the timeout counter is not equal to zero (no at step S19), the process continues at step S5 of FIG. 10.

[0137] In case in step S11, a presence detected message is received (yes at step S11), the process continues with step S21 of FIG. 12. The presence detected message informs on a detection of an object, an address of a luminaire and optional a distance filed. In the step S21, the luminaire determines a distance to the source luminaire, which detected the presence of the object and initially transmitted the presence detected message, using its data storage, the address of a luminaire included in the received message and an optional distance field included in the received message. Next, in a step S22 the luminaire determines a target light level using the determined distance to the source luminaire. Optionally, in case the received message comprises additional information, such as at least one of a velocity of the detected object, travel direction of the detected object and distance from the source luminaire to the detected object, the luminaire may use such additional information for determining the target light level. Next, in a step S23, the luminaire checks whether the determined target light level is greater than a current ambient light level. If this is the case (yes at step S23), the luminaire emits light with the target light level. In a next step S25, the luminaire may forward the received presence detected message. This may be done as outline already above with regard to other FIGs. Next, the process proceeds with step S5 of FIG. 10. In case the determined target light level is lower than a current ambient light level (no at step S23), the process proceeds with step S5 of FIG. 10.

[0138] In case at step S6 the luminaire detects an object in its vicinity (i.e. yes at step S6), the process continues with step S26 of FIG. 12. In step S26, the luminaire transmits a presence detected message that informs on the detection of the object and on the address of the luminaire. In a step S27, the luminaire may emit a maximum light level as a response to detecting the object. The process continues with step S5 of FIG. 10.

[0139] In case at step S7 the luminaires determines that there is a distance to measure for a device (i.e. luminaire) of which the address is stored in the data storage (yes at step S7), the step proceeds to step S12 of FIG. 11. In the step S12, the luminaire transmits an initiator message to another luminaire to which it wants to measure the distance. In a next step S13, the luminaire checks whether it received a responder reply. In case it received such reply (yes at step S13), the luminaire performs with the other luminaire a TWR measurement (cf. step S14). After step S14 the step S15 is performed. In case the luminaire received no reply (no at step S13), the luminaire continues performing the process at step S18.

[0140] In the claims as well as in the description the word "comprising" does not exclude other elements or steps and the indefinite article "a" or "an" does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in the mutual different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.

Claims

1. A luminaire (1) comprising - a communication unit (2) for an ultra-wideband, UWB, radio communication, and - a data storage (3), wherein - the luminaire (1) is configured to - discover, using the communication unit (2), neighboring luminaires within a vicinity of the luminaire (1), - measure, using the communication unit (2), a distance to each discovered neighboring luminaire, and - store in the data storage (3) for each discovered neighboring luminaire the measured distance in association with an address of the discovered neighboring luminaire.

2. The luminaire (1) according to claim 1, wherein - the luminaire (1) is configured to measure, using the communication unit (2), the distance to each discovered neighboring luminaire by performing a two way ranging, TWR, measurement.

3. The luminaire (1) according to claim 2, wherein the luminaire (1) is configured to - delete an address from the data storage (3) in case the discovered neighboring luminaire comprising that address does not respond at least two times in a row during the TWR measurement.

4. The luminaire (1) according to any one of the previous claims, wherein the luminaire (1) is configured to - delete an address from the data storage (3) for which a validity time has expired, preferably under the condition that the neighboring luminaire does not respond in a new measurement.

5. The luminaire (1) according to any one of the previous claims, wherein the luminaire (1) is configured to, in response to the luminaire (1) being electrically connected to an electrical power supply, such as mains, or being powered up, discover the neighboring luminaires within the vicinity of the luminaire (1) and store in the data storage (3) the address of each of the discovered neighboring luminaires.

6. The luminaire (1) according to any one of the previous claims, wherein the luminaire (1) is configured to, in response to the luminaire (1) being electrically connected to an electrical power supply, such as mains, or being powered up, transmit beacons using the communication unit (2).

7. The luminaire (1) according to any one of the previous claims, wherein the luminaire (1) is configured to - receive, using the communication unit (2), a message, the message informing on a detection of an object and on an address of a source luminaire (1a) that detected the object and initially transmitted the message, and - determine, using the data storage (3) and the address of the source luminaire (1a) of the received message, a distance to the source luminaire (1a).

8. The luminaire (1) according to any one of the previous claims, wherein the luminaire (1) is configured to receive, using the communication unit (3), a message, the message informing on a detection of an object, an address of a transmission luminaire (1b) that transmitted the message, and a distance from the transmission luminaire (1b) to a source luminaire (1a) that detected the object, and - determine, using the data storage (3), the address of the transmission luminaire (1b) and the distance from the transmission luminaire (1b) to the source luminaire (1a), a distance to the source luminaire (1a).

9. The luminaire (1) according to claim 7 or 8, wherein - the luminaire (1) is configured to perform an action depending on the determined distance to the source luminaire (1a).

10. The luminaire (1) according to any one of claims 7 to 9, wherein - the received message informs on additional information comprising - at least one of a distance between the detected object and the source luminaire (1a), velocity of the detected object and travel direction of the detected object, and / or - information on the environment of the source luminaire (1a), and - the luminaire (1) is configured to perform an action depending on the determined distance to the source luminaire (1a) and the additional information.

11. The luminaire (1) according to any one of claims 7 to 10, wherein the luminaire (1) is configured to ignore the received message in case - the determined distance to the source luminaire (1a) is greater than a threshold for the distance, or - the received message has been received already within a directly previous time period.

12. The luminaire (1) according to any one of claims 7 to 11, wherein the luminaire (1) is configured to forward the received message by - generating a message that informs on the detection of the object, the determined distance to the source luminaire (1a) and an address of the luminaire (1), and - transmitting, using the communication unit (2), the generated message.

13. The luminaire (1) according to claim 12, wherein - the luminaire (1) is configured to not forward the received message in case the determined distance to the source luminaire (1a) is greater than a threshold for the distance.

14. The luminaire (1) according to any one of the previous claims, wherein - the luminaire (1) comprises a detection unit (4) for detecting an object in a vicinity of the luminaire (1), and - the luminaire (1) is configured to - detect, using the detection unit (4), an object, and - in response to detecting the object, generate and transmit, using the communication unit (2), a message informing on the detection of the object and on an address of the luminaire (1) that detected the object and initially transmitted the message.

15. The luminaire (1) according to claim 14, wherein - the luminaire (1) is configured to generate the message such that the message informs on additional information comprising - at least one of a distance between the detected object and the luminaire (1), velocity of the detected object and travel direction of the detected object, and / or - information on the environment of the luminaire (1).

16. The luminaire (1) according to any one of the claims, wherein - the luminaire (1) is configured to repeatedly transmit, using the communication unit (2), beacons with a frequency, wherein - the frequency is greater during a time period starting with the luminaire (1) being electrically connected to an electrical power supply, such as mains, or being powered up.

17. A luminaire (1') comprising - a communication unit (2) for an ultra-wideband, UWB, radio communication, and - a detection unit (4) for detecting an object in a vicinity of the luminaire (1), wherein - the luminaire (1) is configured to - detect, using the detection unit (4), an object, and - in response to detecting the object, generate and transmit, using the communication unit (2), a message informing on the detection of the object and on an address of the luminaire (1) that detected the object and initially transmitted the message.

18. A system comprising - a luminaire (1) according to any one of claims 1 to 16, and - a luminaire (1') according to claim 17.

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