FIELD OF THE INVENTION

The present invention relates to the field of hybrid application control systems, in particular - but not limited to - Visible Light Communication in lighting control applications. More particular the invention relates to balancing requirements regarding the application functionality and requirements regarding the data communication functionality.

BACKGROUND OF THE INVENTION

Hybrid application networks, such as lighting control applications installed in a building primarily to illuminate the rooms and floors, may additionally be used for data communication using light waves to transmit data to stationary or mobile communication devices or receive data from the stationary or mobile communication devices. Light sources may be used to transmit data to a receiver. Light detectors may be used to receive data transmissions. The light waves may be visible or invisible to the human eye. A major difference to known wireless RF signalling is that light signals are line-of-sight-connections that will be obstructed by obstacles such as walls. A light source may be a luminaire normally used for illumination lighting of a space in a building, e.g. a luminaire that produces artificial light to illuminate the surrounding area. A known system using such light sources for data communication is a Visible Light Communication (i.e. VLC) system. Since a VLC system's main objective is high quality illumination lighting, the data transmit rates are limited by requirements imposed by the primary functionality of the light sources.

US 201 1/0069951 Al discloses a hybrid application control system in which only those light sources, for instances LEDs, provided within a lighting device, for instance a lamp comprising a plurality of LEDs, which are in direct line of sight with a receiving device are selected for data transmission.

EP 2696649 A2 discloses a hybrid communication system in which data transmissions from a base station to a terminal device are provided via light waves using an LED provided at the base station and/or via radio frequency transmission.

In application control systems, such as for instance a lighting control system in a building, actuators (i.e. the lights) are typically installed at rather short distances, e.g. every few meters. Modern lighting applications usually provide an application control plan for controlling the status of respective lighting control components in dependence of predefined lighting scenes; for instance the lighting levels of light sources may be adapted to the amount of daylight measured inside a room. In case of a sunny day, the light sources may even be switched off. Another example could be lights that are switched off at times where no one is present in a particular room or only a limited amount of light sources is switched on, for instance as emergency lighting during the night.

If a particular light source is switched off in accordance with a lighting control plan, for instance in order to save energy, such a lighting component may not be available for data communication. The automated triggering of application scenes in accordance with an application control plan may thus influence or jeopardise proper data transmission or reception, in a hybrid application control system.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved hybrid application control system by ensuring proper data communication while maintaining a desired application functionality.

The object is achieved by the system, method and computer program as defined in the independent claims. Further preferred embodiments are defined in the dependent claims.

In an aspect of the present invention there is provided a control system for directing communication traffic to and from at least one communication unit within a hybrid application control system serving application and communication purposes, the hybrid application control system comprising a plurality of application control components capable of transmitting data to the at least one communication unit using light waves. The control system comprises a network control unit for programming data paths through the application control system to communicate data with the at least one communication unit using a subgroup of application control components within a previously determined area of interest of the first communication unit, and an application plan for controlling respective application statuses of the plurality of application control components. The processing unit configured to derive a communication plan for controlling data transmission requirements of the subgroup of application control components. If the data transmission requirements collide with status requirements set out in the application plan, the processing unit is configured to adapt respective application statuses of application control components comprised in the subgroup of application control components, and/or to adapt the data paths through the application control system to communicate data with the first communication unit by replacing at least one of the application control components of the identified subgroup along the programmed data path by another one of the application control components of the identified subgroup having available resources according to the application plan.

Overruling application scenes to sustain a data communication session within a hybrid application control network by either adapting the lighting levels on the respective emitters or adapt a chosen data path to inject data via another lighting emitter effectively balances the requirements set out in the application plan determining primary functionality tasks of the application control components, e.g. light emitters, capable of transmitting data to a communication unit using light waves, with the requirements of a communication plan. Managing network availability at a required quality for data communication via the application control components enhances the user experience. The overall network performance may thus be improved and failures and/or delays in data transmissions may be reduced or even be avoided. For instance, in lighting control networks, resources required for a specific data communication may be provided without significantly disturbing the lighting application, for instance, in order to provide a certain bandwidth, etc, lighting levels from a particular resource may be compensated by other resources or the overall lighting level may be slightly dimmed, etc. Furthermore, an alternative light emitter could be determined which is not used at its full capacity during a respective lighting scene. In case of reoccurring application scenes and regularly occurring conflicts or balancing requirements with a communication plan, the adapted application statuses and/or alternative data paths, eventually including alternative data injectors may be stored in a file for reuse, in case the application scene is triggered next time. Furthermore, additional input from external sources may be added in order to optimize the balanced output.

In an embodiment the communication plan further defines a required quality of service level for data communication with the first communication unit. In order to guarantee a certain quality of service for the data transmission, a communication unit may request a certain quality of service which may be communicated to the system and being integrated in the communication plan. Certain communication units may also be

automatically assigned a certain quality of service, depending on their type, etc.

In an embodiment the processing unit is configured to identify the subgroup of application control components, wherein the processing unit is configured to determine first position information of a first communication unit within the application control system at a first instant, compute an area of interest for the first communication unit based on at least the first position information, and identify a first subgroup of one or more application control components from the plurality of application control components located within the area of interest of the at least first communication unit.

In an aspect of the present invention there is provided a method for directing communication traffic to and from a communication unit within a hybrid application control system serving application and communication purposes, the hybrid application control system comprising a plurality of application control components capable of transmitting data to the at least one communication unit using light waves. The method comprises

programming by a network control unit data paths through the application control system to communicate data with the first communication unit using a subgroup of application control components within a previously determined area of interest of the first communication unit, providing an application plan for controlling respective application statuses of the plurality of application control components, deriving a communication plan for controlling data transmission requirements of the subgroup of application control components. If the data transmission requirements collide with the status requirements set out in the application control plan, the method comprises adapting respective application statuses of application control components comprised in the subgroup of application control components, and/or adapting the data paths through the application control system to communicate data with the first communication unit by replacing at least one of the application control components of the identified subgroup along the programmed data path by another one of the application control components of the identified subgroup having available resources according to the application plan.

In an embodiment the communication plan further defines a required quality of service level for data communication with first communication unit.

In an embodiment the first subgroup of one or more application control components is selected by determining the positions of the application control components within the application control system; determining first position information of a first communication unit within the application control system at a first instant; computing an area of interest for the first communication unit based on at least the first position information; and identifying a first subgroup of one or more application control components from the plurality of application control components located within the area of interest of the first communication unit. In an aspect of the present invention there is provided a computer program executable in a processing unit, the computer program comprising program code means for causing the processing unit to carry out a method as defined in claim 4 when the computer program is executed in the processing unit.

It shall be understood that the control system and method for directing communication traffic to and from at least a first communication unit within a hybrid application control system of claims 1 and 4, respectively, and the computer program of claim 7 have similar and/or identical preferred embodiments, in particular, as defined in the dependent claims.

It shall be understood that a preferred embodiment of the present invention can also be any combination of the dependent claims or above embodiments with the respective independent claim.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following drawings:

Figure 1 shows a domain model of a lighting control system in accordance with a preferred embodiment;

Figure 2 shows example use cases of preferred embodiments of the present;

Figure 3 shows an example use case with one mobile receiver passing through rooms R3, Rl and R4 of Fig. 2;

Figure 4 shows an example use case with two mobile receivers crossing path as depicted in room R4 of Fig. 2;

Figure 5 shows an exemplary use case of two mobile receivers moving in parallel through room R6 of figure 3.

DETAILED DESCRIPTION OF EMBODIMENTS

Some embodiments are exemplary described in the context of lighting control applications as preferred embodiments. However, it is to be understood that the embodiments are not restricted to lighting control applications. The person skilled in the art will appreciate that the methods and devices may be exploited for any other control application system requiring a similar system topology. In the following a software defined application (SDA) system provides knowledge about application specific requirements and instructions as stipulated in an application plan comprising one or more application scenes. For instance, an example of an SDA system is a software defined lighting (SDL) system that defines a lighting plan comprising one or more lighting scenes. A lighting scene may for example define

dependencies or interactions between application control components, e.g. which lamps are to be switched on if a particular sensor is triggered. The lighting scenes may be defined for specific timeslots, such a day or night, weekdays, weekends, and so on.

A network management system such as a software defined networking (SDN) system provides knowledge about the respective network components present in a mesh network constituting the backbone network of the application system and may control configuration of data communication paths by e.g. forwarding tables and the like. However, the network management system does not know about application specific connections between certain network components.

Together the SDA system and the network management system constitute a software defined control (SDC) system which combines both layers (application and network). The SDC system maps the application/lighting components onto the network topology and thus has the knowledge to decide which components or component parts may be switched off without degrading the capability of the (lighting) control network to execute a (lighting) application.

Figure 1 illustrates a domain model of a lighting control system 300 as a preferred embodiment of the present invention. A (Software Defined) Control System 200 comprises of a (Software Defined) Application system 203 and a network management system 231. The SDC system 200, subject to its application plan 204 and the application scenes stipulated therein, can consult a network management system 231 and dynamically configure communication paths 180, e.g. one or more data forwarding devices, through a communication network 100 to a lighting control component 301 that is connected to a network border component 1 10 and that is deemed suitable to emit data embedded in light waves to a detector 302 comprised in or at least communicatively coupled to a data communication end node 400. The data communication will be described in the following for the direction in which data messages are transmitted from the communication network 100, via data emitters 301, to a data communication end node 400 as receiving unit, which may be stationary or moving e.g. being carried around by persons or a roving apparatus within the building. However, the person skilled in the art will appreciate that data communication from a (mobile) communication end node 400 to the communication network 100 is also possible by simply exchanging the emitter and receiver functionality. Hence, instead of having a light detector/receiver unit 302 at the data communication end node 400 to receive data messages embedded in light waves, the data communication end node 400 may have alternatively or additionally a light emitter unit 302 to emit light waves carrying embedded data

transmissions. Likewise, at the network side, light detectors 301 may be provided to receive light transmission from the data communication end node 400 carrying embedded data communication.

Optionally, a hybrid data communication system may be implemented by RF transceivers 41 1, 412 establishing a further link between the data communication end node 400 and a network border component 1 10 within communication network 100. In addition to transmitting messages via light waves, the system also enables RF communication, in particular for communication from the data communication end node to the communication network. The data communication between the network border components 1 10 and the application control components or RF transceivers 41 1 , 412 may be wireless or wired, with or without additional power provision, e.g. power over Ethernet.

Figure 2 illustrates an exemplary building plan with a hybrid application control system having a plurality of lighting control components, such as light emitters Ll- L34, whose primary task is to provide illumination light, as well as light emitters Txl-Tx3 for embedded data communication. Both light emitters types, LI ..L34 as well as Txl ..Tx3, are capable of embedding data imperceptibly in the light of the system (i.e. visible light communications or VLC), using visible or invisible light emissions such as for example but not limited to laser, IR or UV light (i.e. Free Space Optics or FSO). There may be a single or a plurality of lighting control components inside a defined area of a building. The lighting control components which primarily serve as illumination lighting devices L1-L34 may be switched on or off depending on the actual need for illumination light. Furthermore, the system may comprise light detectors D, such as e.g. presence detectors, daylight sensors etc. The presented system will dynamically adapt operation to use the available lighting control components for data communication as effectively as possible. Light emitters whose primary task is the provision of illumination lighting are also referred to as slow emitters L1-L34, wherein light emitters dedicated to data transmission are also referred to as fast emitters Txl- Tx3. Examples are for instance - but not limited to - emitters using changes in light levels (on, off, dimming, colours), using multiple colours simultaneously (e.g. RGBW), a laser source or IR or UV sources. These latter examples work best in combination with respective receiver, such as for example an optimized photo detector.

The end nodes receiving data communication via the hybrid lighting control system may be stationary, e.g. printers, PCs etc., or mobile e.g. devices carried around by a person or a roving device, for example a cleaning robot, etc. Figure 2 further shows persons, each supposed to carry a mobile data communication end node 400, in the following referred to as mobile receivers Al - A9. The following scenarios are shown:

There may be a single or a plurality of light emitters inside a particular area of a building. Some of the emitters may have a double function and serve data communication purposes and illumination purposes. Depending on a corresponding lighting plan the emitters for providing illumination light may be turned on or off. For example:

1. In room R2 a light band function shall be implemented. A first band shall be constituted by light emitters L7, Tx2 and L14 and a second band by light emitters L27, Tx3, L26 and L28. Band 1 is close to the window and may be dimmed/off on a bright day while band 2 in the middle of the room may be dimmed or switched on to provide a homogeneous illumination throughout the entire room.

2. In room R4, two zone functions shall be defined in a lighting plan. Zone 1 shall be constituted by lights LI 1, L8, L13, L10 and zone 2 by lightsL6, L8, L9..L1 1, L13, LI 5, LI 7..25. Zone 1 is for example a band of high intensity lights and zone 2 with lights dimmed or off.

3. A power saving function may be defined in the lighting plan for room R6. Room R6 is a transit space and when no one is present the lights L30,..,L34 are switched off. The lighting plan stipulates that at certain moments the lights are entirely off and only entrances may be lit by the emergency lights above the exit doors. A lighting plan may define any lighting scene suitable for a specific area within a building and is not limited to the above described scenes which are presented as illustrative examples.

Since light emissions are limited to direct line-of-sight connections, data transmission embedded in light waves may only be provided to a mobile receiver A1-A9 via light emitters in the vicinity of a respective mobile receiver. The hybrid communication system may determine an area of interest for each mobile receiver, either stationary or moving via which a data message could be transmitted to the mobile receiver at a particular point in time. Especially for moving receivers the area of interest is continuously changing. The system may determine future positions based on a path prediction derived from previous movements and check for emitter candidates along a predicted path through the building. The current and predicted areas of interest are compiled in a communication plan keeping track of all communication sessions, wherein the communication plan may also determine respective quality of service parameters for the communication sessions, e.g. bandwidth, error rate, priority etc.

Should the requirements set out in the communication plan conflict with those defined in the lighting plan, either because the lighting requirements according to the lighting plan change or because the mobile receivers change positions and the communication plan is adapted, the software defined control system may apply a suitable mitigation strategy to optimally serve both requirements as set out in the communication plan and in the lighting plan. For example, the lighting plan may be overridden when one (moving) mobile receiver requires a light to be at a different lighting level than set out in the lighting plan in order to sustain data communication. Some examples use cases are outlined in the following:

• Scenario 1 : For room R2, the system has computed that the area of interest for a predicted movement of A5 can be fully covered by fast emitters Tx2 and Tx3. The system determines in accordance with the lighting plan that the light band function may dim or switch off all illumination lights in band 1 and 2. The data communication is sustained by using the fast emitter Tx2 closest to the moving communication unit A5. When A5 is moving to another location inside room R2, the system can ensure a smooth change over to fast emitter Tx3 and the lights L7, L14, L26..L28 may remain switched off as stipulated in the lighting plan.

• Scenario 2: For room R4, with its two zones, zone 1 ,in straight line with the door and zone 2, the remaining area, the application plan defines that zone 1 is likely to remain lit at full brightness while zone 2 is and will be dimmed. The system may determine that under all circumstances LI 1 should remain lit due to the transit function of LI 1 between room Rl and R4. The system thus may override the lighting plan and alternatively change the status of one or more lights in zone 1 to a higher intensity to sustain data communication when communication units Al enters the room at t3 even though A6 and A7 already traversed the room and only require data emitters in zone 2 at t3. Fig. 3. shows the light emitters injecting data messages for receiver Al at subsequent moments in time tO— 13. Fig. 4 illustrates the movement of mobile receivers A6 and A7, whose paths cross at time t2 closest to light emitter L22. In a preferred embodiment the maximum bandwidth is offered to each them as long as they are positioned under different emitters L8, L24 and LI 8 as well as L9 and LI 9, respectively. At time t2 both mobile receiversA6 and A7 are positioned closest to emitter L22. The system will offer a multiplexed data-stream for both mobile receivers to receive as well as information how each individual mobile receiver can retrieve its data from the multiplexed data stream.

• Scenario 3 : For room R6, which is supposed to be lit only by the emergency lights above the doors, the system may determine to override the application plan and periodically switch on those lights closest to moving mobile receivers A8 and A9, for example in an interleaving sequence as depicted in Fig. 5. In a preferred embodiment, the assignment of emitters to A9 is effectively delayed with respect to A8 to avoid that A8 and A9 share the same emitter, e.g. multiplexing and thus only having parts of the bandwidth for each mobile receiver. Alternative emitter assignment may be chosen to avoid concurrent usage of the same emitters. In dense networks an interleaved emitter assignment could be applied.

Alternatively or in addition, the system may adapt the choice of a light emitter as data injector and select an alternative emitter within the vicinity of the mobile receiver that is available for data transmission in view of the requirements set out in the applied application plan.

The person skilled in the art will appreciate that any suitable overriding scenario may be implemented. As such the system dynamically balances the usage of the emitters against multiple requirements: for example ambient lighting according to rules of a lighting plan and data transmission requirements according to a data communication plan.

The system may thus prevent the lighting plan to switch off application control components that are required for a data communication session with a stationary or moving communication unit. As soon as an application control component is no longer required to sustain a data communication session, the system may re-establish the configuration as set out in the lighting plan and may accordingly switch off respective application control component.

Data communication between the mobile receivers and the application control network may be performed using a variety of existing technologies to enhance data communication, such as for example multiplexing (e.g. OFDM) or special modulation techniques (e.g. VPPM, CSK, OOK).

Procedures like determining positions, computing an area of interest, identifying a subgroup and programming and adapting data paths, et cetera performed by one or several units or devices can be performed by any other number of units or devices. These procedures and/or the control of the application control system in accordance with the method for directing traffic can be implemented as program code means of a computer program and/or as dedicated hardware.

A computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium, supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.