LUMINAIRE AND METHOD FOR WIRELESS DATA TRANSFER USING SUCH A

LUMINAIRE

A luminaire is provided. Moreover, a method for wireless data transfer is provided.

An object to be achieved is to provide a luminaire which is capable of energy-efficient wireless data transfer.

According to at least one embodiment, the luminaire comprises one or a plurality of optoelectronic semiconductor chips. Preferably, the optoelectronic semiconductor chips are light emitting diodes, LEDs for short. As an alternative, the optoelectronic semiconductor chips are laser diodes, LDs for short .

According to at least one embodiment, the at least one optoelectronic semiconductor chip is configured to emit a first pulsed radiation. The first pulsed radiation is for example near-ultraviolet radiation, visible radiation and/or near-infrared radiation. A mean frequency the first pulsed radiation is modulated with is preferably at least 1 MHz or at least 10 MHz or at least 100 MHz. In particular, the pulsing of the first pulsed radiation is done in a digital manner, that is, by switching on and turning off the at least one optoelectronic semiconductor chip. A current by which the optoelectronic semiconductor chip is operated is thus

preferably not modulated beside turning on and turning off.

According to at least one embodiment, the luminaire comprises one or a plurality of photodetectors. The at least one photodetector is designed to detect a second pulsed

radiation. The second pulsed radiation does not stem from the at least one optoelectronic semiconductor chip. By way of example, the photodetector is a photodiode. As an

alternative, the photodetector can have a plurality of sensitive regions and might be a CCD chip.

According to at least one embodiment, the luminaire includes a wire-based data interface. Said interface is to receive and to send digital data. A bit rate for the data transfer via is preferably at least 1 Mbit/s or at least 10 Mbit/s or at least 100 Mbit/s or at least 1 Gbit/s or at least 10 Gbit/s. Due to the data interface, the luminaire is connected to a data line, which is for example a glass fiber. In particular, the luminaire is connected to the Internet or to a telephone net by means of the data interface.

According to at least one embodiment, the luminaire comprises one or a plurality of electronics units. The at least one electronics unit is to control the at least one

optoelectronic semiconductor chip in order to emit the first pulsed radiation at least partly according to a data input received at the data interface and to convert the detected second pulsed radiation at least partly to a data output to be sent at the data interface. In other words, the luminaire receives input data at the interface, said data is processed in the electronics unit and is sent by the optoelectronic semiconductor chip. On the other hand, light signals are received by the photodetector and are converted to output data by the electronics unit, said output data being sent by the luminaire through the interface. According to at least one embodiment, the luminaire is capable for light fidelity, Li-Fi for short. Thus, wireless data transfer can be achieved by the luminaire by sending and receiving light instead of radio waves as in the case of Wi Fi .

According to at least one embodiment, at least 60% or at least 80% or at least 90% of an average power consumption of the luminaire is used to produce visible light. Hence, the majority of the energy consumed by the luminaire is to eliminate a surrounding of the luminaire. Thus, in terms of energy consumption the receiving and sending of data is not the main function of the luminaire. Hence, the luminaire is a combined device for producing light and also for wireless data transfer.

According to at least one embodiment, the light emitted by the luminaire appears of constant brightness to the human eye. That is, the radiation used in particular to send the data is modulated so fast that the human eye cannot sense said modulation. As an alternative, the first pulsed

radiation is not in a spectral range to which the human eye is sensitive. As a consequence, for an observer of the luminaire the luminaire just looks like a common light source for illumination purposes.

In at least one embodiment, the luminaire comprises at least one optoelectronic semiconductor chip to emit a first pulsed radiation, at least one photodetector to detect a second pulsed radiation, a wire-based data interface to receive and to send digital data with a bit rate of at least 1 Mbit/s and at least one electronics unit to control the optoelectronic semiconductor chip in order to emit the first pulsed radiation at least partly according to a data input received at the data interface and to convert the detected second pulsed radiation at least partly to a data output to be sent at the data interface so that light fidelity is realized. At least 60% of an average power consumption of the luminaire is used to produce visible light that appears of constant brightness to the human eye.

With said luminaire, which is preferably a streetlight, it is possible to provide an alternative to radiofrequency-based mobile telecommunications networks. As preferably

streetlights are used, no additional infrastructure for the Li-Fi is needed.

In traditional cellular communication networks, the network is distributed in segments called cells, each cell being served by at least one fixed-location transceiver, known as a cell site or base transceiver station (BTS) . This base transceiver station provides the cell with the network coverage which can be used for transmission of voice, data and others. Therefore, each time the network bandwidth or network coverage needs to be increased, the base transceiver station needs to be upgraded or a new one needs to be built. This can be quite expensive. The exponential increase in mobile data transfer in the last few decades has led to an increase of wireless systems deployment. As a consequence of this, the RF spectrum has become congested.

BTS needs a lot of energy to transmit or receive wireless signals. The largest consumer of energy in wireless mobile communication is a BTS. This is due to two main reasons. The first reason is an inefficient RF power amplifier, which consumes 60% to 70% of the total energy supplied and only a small part of the energy is converted into useful output. The second reason is that the non-uniform traffic load in the network points to improper and inefficient planning of radio resources. The mobile phone traffic in a cell area (BTS area) is uncertain, it changes from hour to hour and day to day. Hence the transmission rate changes as well.

The invention described here would address the following issues: cost, limited spectral capacity, and energy

consumption. The proposed luminaire uses Li-Fi technology to address these issues. Li-Fi or Light Fidelity is a Visible Light Communications (VLC) System running wireless

communications travelling at very high speeds. Li-Fi can use common household LED (light emitting diodes) lightbulbs to enable data transfer. Therefore, by utilizing existing streetlight networks and/or lighting networks in buildings to form a seamless intricate communication network, the above- mentioned three issues faced by a traditional cellular communication network can be dealt with.

In an RF-based cellular network, a land area is divided into hexagonal cells depending on terrain and reception

characteristics. Each of these cells is assigned with

multiple frequencies, which have corresponding base

transceiver stations (BTS) . These BTS provide the cell with the network coverage which can be used for transmission of voice, data and others. The group of frequencies can be reused in other cells, provided that the same frequencies are not reused in adjacent and/or neighboring cells as that would cause co-channel interference.

The BTS are connected to one another via central switching centers which track calls and transfer them from one base station to another as callers move between cells. The handoff is ideally seamless and unnoticeable . Each base station is also connected to the main telephone network and/or internet and can thus relay mobile calls to landline phones.

In a transmitter system, digitalized information from a base station controller (BSC) is encoded and modulated using various modulation schemes available before being converted to an RF domain for transmission.

Wireless cellular communication using the current method of transmission based on radiofrequency in particular suffers from limited spectrum capacity and high energy consumption. Concerning the limited spectrum capacity, global mobile data traffic grew about 63% in 2016. Global mobile data traffic reached 7.2 exabytes per month at the end of 2016, up from 4.4 exabytes per month at the end of 2015. This exponential increase in mobile data traffic has led to the massive deployment of wireless systems based on RF. As a consequence, the limited available RF spectrum is subject to an aggressive spatial reuse and co-channel interference has become a major capacity-limiting factor. This could lead to an "RF spectrum crisis " .

Visible Light Communications (VLC) systems running wireless communications travelling at very high speeds could

potentially offload a large portion of the network traffic from the overcrowded RF domain and hence help to avoid an "RF spectrum crisis". The common VLC today is known as Li-Fi or Light Fidelity.

Li-Fi is similar to Wi-Fi technology as both transmit data electromagnetically . However, Wi-Fi uses radio waves while Li-Fi runs typicality on visible light or near infrared radiation. Li-Fi is a Visible Light Communications (VLC) system. This means that it utilizes a photodetector to receive light signals and a signal processing element to convert the data into binary content which can be streamed out digitally.

An LED lightbulb is a semiconductor device. This means that the constant current of electricity supplied to an LED lightbulb can be manipulated at extremely high speeds, without being visible to the human eye. For example, data is fed into an LED light bulb with signal processing technology, it then streams out the binary data embedded in its beam at high speeds to a photodetector like a photodiode. The tiny changes in the rapid dimming of LED bulbs is then converted by the receiver into an electrical signal. This signal is then converted back into a binary data stream. Therefore, standard signal encoding in telecommunication like TDMA, CDMA can be applied in the binary data stream.

Concerning the energy issue, most energy used by wireless devices eventually turns into heat. The more energy a device uses, the more heat it produced. Transistors usually work more reliably when they work at normal temperature. If they are overheated, they start malfunctioning or are totally destroyed. In order to decrease the temperature, typically a large cooling system, which is not realistic for the mobility of wireless devices, might be needed. Furthermore, the cooling system might require more power to be run, which in turn causes more heat.

As already pointed out above, power amplifiers in transmitter and receiver systems in the BTS use the most power. By utilizing Li-Fi technology, the inefficient power amplifier could be replaced with LED lighting and LED drivers to perform the transmitting while using photodetectors to receive data. The framework for this communication could be implemented by using the established protocol of orthogonal frequency division multiplexing (OFDM) . LED driver circuits utilize much less energy and the energy loss is much smaller compared to that of a power amplifier deployed under the traditional transmitter and receiver system.

In the transmitter setup described here, the information or series of binary data is preferably first demultiplexed into N parallel streams, and each one can be mapped to a complex symbol stream using some modulation constellation like QAM, PSK, or the like. An inverse Fast Fourier transform, FFT for short, is computed on each set of symbols, giving a set of complex time-domain samples. Preferably these samples are then quadrature-mixed to passband in the standard way. The real and imaginary components can then be summed into a stream of signals which could then be used to modulate the flicker of the LED via an LED drivers and/or combiners module .

In the receiver system for the luminaire, sampling can be done by using a photodetector based multi-coupler, and a forward FFT is used to convert back to the frequency domain. This returns N parallel streams, each of which is converted to a binary stream using an appropriate symbol detector. These streams can then be re-combined into a serial stream, which is an estimate of the original binary stream at the transmitter . On a macro scale, the Li-Fi-capable transmitter and receiver system could utilize streetlights instead of dedicated RF antennas .

By utilizing streetlights, for example, the energy

consumption can be confined to that of street energy

consumption, instead of additional power being used for communication purposes only. No additional BTS need to be built when a capacity upgrade or an expansion is needed.

Concerning costs, a streetlight network is essential in any location where people converge. Therefore, the basic

infrastructure for Li-Fi is already existing. By tapping on this intricate network, costs can be saved and a detailed network is already available for Li-Fi. This offers a

significant and huge potential for cost saving.

Regardless of the network technologies ranging from the humble 2G network to the advanced 4G LTE or even 5G, a base transmission station (BTS) is a necessity. The investment for setting up BTS for capacity expansion or network upgrade is huge. The operating cost of a BTS is also high, due to its energy consumption. The high energy need is particularly due to the inefficient RF power amplifier, which consumes 60% to 70% of the total energy supplied, and only a small part of the energy is converted into useful output. The luminaire described here uses inexpensive components like LEDs, LED drivers, photodetectors to replace power amplifiers and RF combiners to realize preferably the orthogonal frequency division multiplexing (ODFM) protocol.

As a driver for the luminaire described here a so-called buck converter can be used, for example the buck converter AP1509 from Diodes Incorporated. Such buck converters reach

efficiencies of up to 90% or higher with the most loss occurring when the active component is operating. Therefore, by substituting a power amplifier with an LED driver

circuitry, high efficiency in energy conversion can be ensured .

Visible Light Communications (VLC) systems running wireless communications, which use visible light between 400 THz (780 nm) and 800 THz (375 nm) as an optical carrier for data transmission and illumination, travelling at very high speeds could potentially offload a large portion of the network traffic from the overcrowded RF domain and hence help to mitigate the looming RF spectrum crisis.

Up to the present day, the visible light spectrum includes 100s of THz, of license free bandwidth. This is about 10,000 times more than the entire RF spectrum up to 30 GHz. Recent research, too, has shown that data rates in excess of 1 Gbit/s can be obtained using off-the-shelf phosphor-coated white LEDs, and 3.4 Gbit/s has been demonstrated with an off- the-shelf red-green-blue (RGB) LED.

Another advantage of having a Li-Fi-capable network

architecture is that a full Li-Fi-enabled cellular

communication could potentially be created by integration of Li-Fi wireless communication inside a building with the Li-Fi capable network architecture similar to 3G. This could offer a low-cost solution for creating a seamless network of communication inside and outside structural buildings.

According to at least one embodiment, the luminaire is a streetlight. Preferably, the luminaire then has a designed luminous flux of at least 2000 lm or 2500 lm or 3500 lm or 5000 lm.

According to at least one embodiment, the luminaire is a room light. In this case, a designed luminous flux of the

luminaire amounts to preferably at least 500 lm or 700 lm or 1000 lm.

According to at least one embodiment, the luminaire has an illumination range and/or a receiving range of at least 30 m or 50 m or 80 m along at least one direction. It is possible that said range is of circular shape when seen in top view so that the luminaire may cover an area all around the

luminaire .

According to at least one embodiment, the luminaire further comprises a light source to produce at least 90% or 95% or all of the visible light emitted by the luminaire. While in operation, the light source is preferably operated in

continuous wave mode, that is, the light source then is not or not significantly modulated. Preferably, the light source is based on semiconductor devices like LEDs. In this case it is possible that only the at least one optoelectronic

semiconductor chip is modulated to send the data input.

According to at least one embodiment of the luminaire, the at least one optoelectronic semiconductor chip is designed to produce at least 90% of the visible light emitted by the luminaire while in operation. In this case, the at least one optoelectronic semiconductor chip is also modulated to send the data input. Thus, both the generation of visible light for illumination proposes as well as the generation of the first pulsed radiation for data transmission is done by the at least one optoelectronic semiconductor chip.

According to at least one embodiment, the at least one optoelectronic semiconductor chip and/or the at least one photodetector are located at a height of at least 3 m or 4 m or 6 m above ground level. With such a comparably large height it is possible to increase a range of the luminaire and to send and/or receive data across car tops.

According to at least one embodiment, the electronics unit includes one or a purity of the following elements: a base station controller (BSC) , a power supply unit (PSU) , drivers preferably for a plurality of the optoelectronic

semiconductor chips, combiners for the optoelectronic

semiconductor chips, one or a purity of transceivers, and a multi-coupler. It is possible that said components are integrated in one single chip or that said components are assembled as individual components for example on a printed circuit board. Moreover, it is possible that the different elements of the electronics unit are distributed over the different parts of the luminaire.

According to at least one embodiment, the electronics unit is configured as a base transceiver station, BTS for short.

According to at least one embodiment, the electronics unit includes one or a plurality of fast Fourier transform

calculators, FFT for short. In this case, the electronics unit is preferably designed for orthogonal frequency division multiplexing . According to at least one embodiment, the first pulsed radiation emitted by the at least one optoelectronic

semiconductor chip is near-infrared radiation. In this configuration it is particularly possible that there is a plurality of optoelectronic semiconductor chips emitting at different wavelengths. For example, at least one

optoelectronic semiconductor chip that emits visible light is combined with one or a plurality of semiconductor chips emitting near-infrared radiation, possibly at different peak wavelengths in the near-infrared spectral range.

Moreover, a method for wireless data transfer is provided.

The method uses one or, preferably, a plurality of luminaires according to one or a plurality of the embodiments described above. Thus, features of the luminaire are also disclosed for the method and vice versa.

In one embodiment of the method, in operation the at least one luminaire sends and receives data from at least one movable participant with a bit rate of at least 1 Mbit/s and at least 60% of an average power consumption of the luminaire is used to produce visible light that appears of constant brightness to the human eye.

Constant brightness can mean that neither the luminous flux nor the color of the light varies for the human eye.

For example, the movable participant is a pedestrian or a vehicle like a car, a bike, a motorbike or a lorry.

According to at least one embodiment of the method, a

plurality of the luminaires is used, each one having a maximum range within which the data can be received and sent to the at least one movable participant. Thus, a cell is defined within the respective luminaire that is capable to receive and to send the data.

According to at least one embodiment, the luminaires are arranged so that the adjacent cells overlap. Thus, the movable participant can always be connected to at least one of the luminaires and can receive and send data all the time.

According to at least one embodiment, the luminaires are operated with orthogonal frequency division multiplexing (OFDM) using ultraviolet, visible and/or infrared radiation. The frequencies used by adjacent luminaires for the OFDM to receive and to send the data preferably differ from one another .

According to at least one embodiment, the luminaires are arranged in at least one line along a street. In this case, the at least one movable participant can be a car that drives on said street. The data link to the luminaire can be

realized for example by a headlight of the car. As an

alternative, the car may also have an additional light source to send data to the luminaire, whereupon said data are received by the photodetector of the luminaire.

According to at least one embodiment in which a plurality of the luminaires is used, at least some of said luminaires are coupled together and communicate in a wire-based manner with each other to form a group. It is possible that one of the luminaires in the group serves as a master and that the remaining luminaires serve as slaves. According to at least one embodiment, said group is coupled to a mobile telecommunications network using ultra-high radio frequency, UHF for short.

According to at least one embodiment, only one luminaire of said group is directly coupled to the mobile

telecommunications network, whereas the other luminaires of the group are only indirectly coupled to the mobile

telecommunications network. By this configuration, only some of the luminaires need a fully equipped electronics unit and the other luminaires of the group can have a simplified electronics unit or can also use the electronics unit of the luminaire directly coupled to the mobile telecommunications network .

A luminaire and a method described herein are explained in greater detail below by way of exemplary embodiments with reference to the drawings. Elements which are the same in the individual figures are indicated with the same reference numerals. The relationships between the elements are not shown to scale, however, but rather individual elements may be shown exaggeratedly large to assist in understanding.

In the Figures:

Figure 1 shows a schematic representation of an exemplary embodiment of a luminaire described here,

Figures 2 to 5 show schematic set-ups of communication

systems comprising an exemplary embodiment of a luminaire described here, and Figure 6 shows schematic sectional views of exemplary embodiments of luminaires described here.

In figure 1 an exemplary embodiment of a luminaire 1 for Li- Fi communication is shown. The luminaire 1 is configured as a streetlight. To produce light, the luminaire 1 comprises one or a plurality of optoelectronic semiconductor chips 2 to produce visible light L. Moreover, the optoelectronic

semiconductor chip 2 is configured to emit a first pulsed radiation S towards a participant 7. By the modulated first pulsed radiation S, data can be sent by the luminaire 1.

Preferably, the optoelectronic semiconductor chip 2 is modulated via OFDM. The modulation and pulsing of the

optoelectronic semiconductor chip 2 is carried out so fast that it cannot be recognized by the human eye.

As an option, there can also be a light source 6 to produce the visible light L. If such a light source 6 is present, it is possible that the optoelectronic semiconductor chip 2 is only there to produce the first pulsed radiation S to send data .

Moreover, the luminaire 1 includes a photodetector 3 to detect a pulsed radiation R from the at least one participant 7, the second pulsed radiation R also contains optically coded data as well as the first pulsed radiation S. For example, the photodetector 3 is located at a pillar of the luminaire 1. The optoelectronic semiconductor chip 2, the photodetector 3 and the optional light source 6 are

electrically coupled to and driven by an electronics unit 5 of the luminaire 1. Moreover, there is a data interface 4, by which the luminaire 1 receives data for example from a telecommunications network like the internet. Data received by the luminaire 1 can also be sent to the telecommunications network by means of the interface 4. Preferably, the data interface 4 is wire-based. As an alternative, the data interface 4 can be wireless.

Preferably, the luminaire 1 is configured as a base

transceiver station BTS. For this propose, the electronics unit 5 includes a base station controller BSC. Moreover, there can be a transceiver T and a multi-coupler M. To energize the optoelectronic semiconductor chip 2, there is preferably a power supply unit PSU and LED drivers D and/or LED combiners C. These components can be integrated in an integrated circuit or can exist as separate components mounted for example on a printed circuit board. Moreover, optimally these components are distributed over different parts of the luminaire 1 so that the electronics unit 5 does not need to be a single element.

In figure 2, a possible data network architecture is

illustrated. There is one or, preferably, a plurality of the Li-Fi-capable luminaires 1. Each luminaire 1 can be connected to a radio network controller RNC. Otherwise, the luminaires 1 are assembled in groups, wherein only one luminaire 1 of said group is connected to the RNC. The network can be configured for example as a 3G network for voice and data transmission. This means that the RNC can be coupled to a mobile switching center MSC and/or to a serving GPRS support node SGSN. Further, there can be connections to a gateway mobile switching center GMSC and to a gateway GPRS support node GGSN. Moreover, there are connections to a public switched telephone network PSTN and the public internet PI.

Of course, different network architectures can also be used for the luminaires 1. In figure 3 it is illustrated that a plurality of luminaires 1 are arranged along a street 9. Each of the luminaires 1 has a distinct range in which it can receive data and can send data, thus forming cells 8. The cells 8 of adjacent

luminaires 1 overlap so that the complete street 9 is covered by the cells 8. In the street 9, there is a couple of

multiple participants 7, for example, cars. By means of the pulsed radiations R, S, the participants 7 can communicate bi-directionally with the luminaires 1. Thus, the Li-Fi- capable luminaires 1 can replace a radiofrequency-based mobile communications network along the street 9 for

participants 7 equipped with suitable senders and receivers.

According to figure 3, the luminaires 1 are located along a centerline of the street 9. This is not necessarily the case. As an alternative, the luminaires 1 can also be located along one or along two opposite sides of the street 9.

According to figure 3, the luminaires 1 only cover a one dimensional range along the street 9. Contrary to that, in figure 4 it is shown that the luminaires 1 and, thus, the cells 8 form a two-dimensional network, for example along crossing streets. Moreover, not shown here, it is also possible that the cells 8 of the luminaires 1 cover a closed area in a two-dimensional manner, for example cover a large parking area completely with the cells 8.

In figure 5A it is illustrated that the Li-Fi system covers a building 11. This is done for example by external light from the luminaire 1, which is a streetlight. Other than shown, in the building 11 itself there can be luminaires, too, to fully enable Li-Fi communication within the building 11. This is in particular possible in stairways facing a street.

A similar configuration is shown in figure 5B, where the emphasis is on luminaires 1 within the building 11. The internal luminaires 1 and external luminaires 1, for example streetlights, together form a Li-Fi network.

In connection with figure 6, different possible embodiments of the luminaire 1 are shown focusing on the principle set up. These luminaires 1 as drawn in figure 6 can be used in all the other embodiments, of course.

According to figure 6A, there is a plurality of the

optoelectronic semiconductor chips 2. The optoelectronic semiconductor chips 2 are enclosed in a housing together with the photodetector 3. For example, the housing comprises a reflector side 13 and a light exit face 12. The light exit face 12 can be equipped with lenses as an option. The

electronics unit 5 and the data interface 4 are arranged in the proximity of the housing.

The optoelectronic semiconductor chips preferably comprise a semiconductor layer sequence in each case. Said semiconductor layer sequence is preferably based on a III-V compound semiconductor material. The semiconductor material is for example a nitride compound semiconductor material such as Al _n In _] __ _n-m Ga _m N or a phosphide compound semiconductor material such as Al _n In _] __ _n-m Ga _m P or also an arsenide compound

semiconductor material such as Al _n In _] __ _n-m Ga _m As, wherein in each case 0 £ n £ 1, 0 £ m £ l and n + m £ 1 shall apply. The semiconductor layer sequence may comprise dopants and additional constituents. For simplicity's sake, however, only the essential constituents of the crystal lattice of the semiconductor layer sequence are indicated, i.e. Al, As, Ga, In, N or P, even if these may in part be replaced and/or supplemented by small quantities of further substances. The semiconductor layer sequence is particularly preferably based on the AlInGaN material system. The same can apply for all other exemplary embodiments.

In the exemplary embodiment of figure 6B, the photodetector 3 is located at a pillar 14 of the luminaire 1. The data interface 4 and the electronics unit 5 can be located at a base of the pillar 14. Hence, the photodetector 3 is at quite a distance from the optoelectronic semiconductor chips 2.

According to figure 6C, there are two housings each

comprising optoelectronic semiconductor chips 2. The

plurality of photodetectors 3 can be arranged near said housings. The data interface 4 and the electronics unit 5 can be located within the pillar 14 at a bottom part of the pillar 14.

As also possible in all the other exemplary embodiments, there can be an additional light source 6 to produce the visible light L emitted by the luminaire 1 while the

optoelectronic semiconductor chips 2 are to produce the first pulsed radiation S to send the data. Preferably, the light source 6 is also based on semiconductor components like LEDs.

In the set-up of the luminaire 1 as shown in figure 6D, the housing is of round shape. The electronics unit 5 can be placed in an interior of the luminaire 1. For example, the photodetectors 3 are located at a bottom side of the housing. Contrary to this, the optoelectronic semiconductor chips 2 and the optional light source 6 are arranged at a top part of the housing in order to provide indirect lighting, for example in a building.

The invention described here is not restricted by the

description given with reference to the exemplary

embodiments. Rather, the invention encompasses any novel feature and any combination of features, including in

particular any combination of features in the claims, even if this feature or this combination is not itself explicitly indicated in the claims or exemplary embodiments.

List of Reference Signs

1 luminaire

2 optoelectronic semiconductor chip

3 photodetector

4 data interface

5 electronics unit

6 light source

7 movable participant

8 cell

9 street

10 mobile telecommunications network

11 building

12 light exit face

13 reflector side

14 pillar

BSC base station controller

BTS base transceiver station

C LED combiner

D LED driver

L visible light

M multi-coupler

PSU power supply unit

R second pulsed radiation to be received

S first pulsed radiation to be sent

T transceiver