Abstract: This invention relates to a binary signaling scheme for use in a transmitter comprising a semiconductor radiation source where the driving current and thus also the radiation output level is modulated by switching the driving current on and off. However, the modulation of the driving current is adapted to not wait for the radiation response to follow the complete rise or fall curve but to switch between two (or a larger number of) selected radiation output levels. During prolonged sequences of zeros (or ones), the driving current is switched to keep the radiation output level between a certain minimum and maximum level. This range of radiation output levels is adaptively selected in accordance with characteristics of the driving current, the optical transmission channel, the radiation source and/or the radiation detector.

Abstract: According to one aspect disclosed herein, there is provided a client device for use in an optical wireless communications network, the client device comprising a transceiver configured to receive data via an optical wireless connection. The transceiver comprises an upward facing optical transducer configured to detect or transmit an optical wireless transmission, the sensor arranged to have a coverage area with at least two 5 concentric segments. A portion of the sensor is configured to provide an outermost segment of the at least two concentric segments.

Abstract: To fully enjoy the benefit of adaptive modulation or bit loading in a multi-carrier wireless communication system, a bit loading control method (700) is disclosed to reduce the system complexity and signaling overhead by making use of an attribute of the communication channel, which has a declining channel response with increasing frequency. Instead of applying adaptive bit loading on a per subcarrier basis, the disclosed method (700) obtains (S703) an estimated channel response based a test signa; and determines (S704) according to the estimated channel response a bit loading scheme for allocating the plurality of subcarriers into one or more non-overlapping frequency segments. For each frequency segment, an individual modulation scheme is assigned, which is shared by the more than one adjacent subcarrier comprised in the same frequency segment. The monotonicity of the channel response is used to accelerate the algorithm, as well as to make control information more compact.

Abstract: This invention proposes a mechanism to improve system performance in an optical wireless communication system by examining whether time slots in time channels are to be scheduled for exclusive use or could be utilized for parallel communication. The examination is based on a cross-over point from tolerating interference to applying time division. A reserved period for each access point is defined within its assigned time channel, which is exclusively reserved for communication with its endpoint(s). This reduces the communication overhead and keeps freedom of adapting slot-scheduling in the exclusive period at the cost of some performance reduction. To minimize this performance reduction, the size of the reserved period can be adapted to the actual need based on the traffic demand for exclusive use and non-exclusive use.

Abstract: A LiFi system having multiple transceivers (11) and a single multiple-input- multiple-output (MIMO) modem (41) with at least M outputs, wherein the M transmit outputs of the MIMO modem (41) are fed to a linear combiner (42). The linear combiner creates M distinct linear combinations based on the N MIMO transmit branch signals of the MIMO modem and the linear combinations are chosen such that they allow decoding of each of the5 N MIMO transmit branch signals when N of the M distinct output signals are received.

Abstract: A system comprising: a plurality of first devices, each configured to transmit a low-frequency, LF, light signal comprising an identifier of the respective first device, and to transmit and/or receive a high-frequency, HF, light signal comprising data content; and a second device configured to receive a LF light signal from each of the first devices, and to transmit and/or receive a HF light signal from at least one first device, wherein the second device has an adaptable receiving and/or transmitting direction for respectively receiving and/or transmitting the HF light signal, and wherein the second device comprises a controller configured to: based on the identifiers encoded in the LF light signals, determine a position of the second device relative to the first devices and select a first device; and based on the determination, adapt the receiving and/or transmitting direction toward the selected first device.

Abstract: A tunable laser based light source for Li-Fi communication comprising a laser (1), a first optical element (3), and a second optical element (4). The first optical element (3) is configured to reflect and/or refract a scanning beam (2) emitted from the laser (1). The second optical element (4) is configured to broaden the scanning beam (2) reflected/ refracted by the first optical element (3). The scanning beam (2) is configured to scan a scanning area extending with a first scanning length in a broadening direction (SI) and a second scanning length in a scanning direction (S2). The second optical element (4) is configured to broaden the scanning beam (2) in the broadening direction (S1) to a width larger than the first scanning length, and the laser (1) and the first optical element (3) are configured to cooperate to enable the scanning beam (2) to be swept along the scanning direction (S2).

Abstract: A modulator for generating an Orthogonal Frequency Division Multiplexing, OFDM, signal, said modulator comprising a subcarrier generator block arranged for generating N/2 consecutive subcarriers based on N/2 input data symbols, a zero padding block arranged for consecutive padding said N/2 subcarriers with N/2 zeros, thereby obtaining N subcarriers, an inverse Fourier Transform generator block arranged for performing an N sized inverse Fourier Transform on said N subcarriers thereby providing N time domain signals at an output, wherein said modulator is arranged to convert said N time domain signals into a time domain OFDM signal, and wherein said modulator further comprises and a block arranged for extracting a real-valued part from an inputted complex-valued time domain signal, which block is connected to said output of said inverse Fourier Transform generator block, such that said converted time domain OFDM signal is a real-valued time domain OFDM signal.

Abstract: A modulator and demodulator for generating an Asymmetrically Clipped Optical, ACO, Orthogonal Frequency Division Multiplexing, OFDM, signal for use in data communication based on a data stream comprising input data symbols. said modulator comprising: an OFDM time signal generator block arranged for generating a time domain OFDM signal based on said input data symbols, a copy-and-flip block arranged for copying and flipping said time domain OFDM signal and appending said copied and flipped real-valued time domain OFDM signal to said time domain signal thereby obtaining a full time domain ACO-OFDM signal. The demodulator follows an inverse approach wherein an un-flip and merge block un-flips a second half of said ACO OFDM signal and merges the un-flipped second half of said ACO OFDM signal with a of said ACO OFDM signal, thereby obtaining a time domain ACO OFDM signal which is they used to retrieve the input data symbols.

Abstract: A signal switch comprises a switch arrangement for selectively passing optical wireless communication, OWC, signals received from a plurality of photodetectors for output to an external device. A signal strength detector is arranged to measure a signal strength of OWC signals as passed by the switch arrangement. While an OWC signal received from a first one of the photodetectors with a signal strength is being passed by the switch arrangement, a selection unit controls the switch arrangement to pass a combination of the OWC signal from the first photodetector and the OWC signal from another photodetector, determines a signal strength of the combination of OWC signals, and estimates the signal strength of the OWC signal from the other photodetector based on the signal strength of the OWC signal from the first photodetector and the signal strength of the combination of OWC signals.

Abstract: The invention relates to a peripheral device for communicating with a host and for controlling a controlled device, to a system including such peripheral device and at least the controlled device and to a corresponding method including a communication and a controlling. In order to allow for a possibility for upgrading controlled devices with further functionality during their service life at low initial costs or efforts on the side of the controlled devices, it is provided for an interconnection between a portion of the system using a complex standard and another portion of the system not using such standard by means of the peripheral device having a dual purpose, as a peripheral device to the standard compliant host and as a controlling device to the controlled device. In both cases, however, power is provided to the peripheral device from either the host or from the controlled device.

Abstract: A camera-based sensor device (200) and method for use in a controllable lighting system (100). The camera-based sensor device (200) comprises: a communications interface (203); a camera (201) for capturing images of a scene, each image comprising an array of pixels; and a processor (202). The processor (202) is configured to determine at least one light performance indicator, LPI, from an image captured by the camera (201). The LPI is a combined metric derived from a plurality of pixels of the array of pixels in the image. The processor (202) is configured to transmit, via the communications interface (203), the determined at least one LPI to the controllable lighting system (100) for use by the controllable lighting system (100) to make a control decision based on the LPI. The processor (202) does not transmit any of the images of the scene.

Abstract: A method and computer device for determining a spatial luminance distribution over at least one image of a scene illuminated by at least one illuminant (121) are provided. The image comprises RGB channels. A linear combination of the RGB channels is applied to determine the luminance distribution. The linear combination has a set of coefficients comprising a respective coefficient for each of the RGB channels. The coefficients are determined by identifying a spectral power distribution, SPD, of the at least one illuminant and performing a search to determine values of the set of coefficients that minimise a spectral mismatch between: a) the identified SPD weighted by the linear combination; and b) the identified SPD weighted by a luminosity function.

Abstract: A communication system, method and apparatus that enable combined illumination and communication of data (e.g. LiFi) by achieving extended coverage using just three or more channels. The combined illumination and communication system comprises an arrangement of luminaires as a regular Bravais pattern based on a convex quadrilateral unit cell on the ceiling. Using a spatial reuse pattern of at least three optical color channels, full coverage for the users in that space can be achieved. The predetermined reuse pattern is configured so that a first channel and a second channel are distributed over the Bravais pattern and a third channel is used to cover dead spot areas where the coverage areas of the first and second channels contact each other. Interference can be avoided to achieve full contiguous coverage without requiring the luminaires to synchronize or to communicate with each other.

Abstract: A system comprising: a plurality of first devices, each configured to transmit a low-frequency, LF, light signal comprising an identifier of the respective first device, and to transmit and/or receive a high-frequency, HF, light signal comprising data content; and a second device configured to receive a LF light signal from each of the first devices, and to transmit and/or receive a HF light signal from at least one first device, wherein the second device has an adaptable receiving and/or transmitting direction for respectively receiving and/or transmitting the HF light signal, and wherein the second device comprises a controller configured to: based on the identifiers encoded in the LF light signals, determine a position of the second device relative to the first devices and select a first device; and based on the determination, adapt the receiving and/or transmitting direction toward the selected first device.

Abstract: A signal switch comprises a switch arrangement for selectively passing optical wireless communication, OWC, signals received from a plurality of photodetectors for output to an external device. A signal strength detector is arranged to measure a signal strength of OWC signals as passed by the switch arrangement. While an OWC signal received from a first one of the photodetectors with a signal strength is being passed by the switch arrangement, a selection unit controls the switch arrangement to pass a combination of the OWC signal from the first photodetector and the OWC signal from another photodetector, determines a signal strength of the combination of OWC signals, and estimates the signal strength of the OWC signal from the other photodetector based on the signal strength of the OWC signal from the first photodetector and the signal strength of the combination of OWC signals.

Abstract: An optical data transmission system and method employs positive only data modulation, with an offset applied to the positive modulated values before generating modulated drive current signals for a light emitting component. The offset is such that the minimum drive current falls in a range where the electron-to-photon efficiency of the light emitting component is substantially constant. The drive current thus falls in a more linear part of its current vs. intensity characteristic. This reduces distortion and hence enables increased data rate.

Abstract: An LED module (200) comprising: a first set of LEDs (D1) for emitting illumination to illuminate an environment, arranged within a first circuit path; a second set of one or more LEDs (D2) for emitting light, arranged within a second circuit path; both the first and second sets being powered by a portion of the power received via a same pair of input terminals, and the first circuit path being longer than the second circuit path; and filter circuitry (206, 208) arranged to filter a modulation in the power received via the terminals, the filtering comprising allowing a component of the modulation at a predetermined modulation frequency to be passed only to the second set of LEDs (D2) and not the first set (D1), thereby causing a corresponding signal to be embedded in the light emitted by the second set but not in the illumination emitted by the first set.

Abstract: An uplink subsystem for use in an illumination system arranged for optical communication as well as the illumination system, the system comprising a downlink subsystem and the uplink subsystem. The uplink subsystem comprises sensors (e.g. infrared sensor) embedded in each luminaire in the group. The uplink subsystem also comprises a demodulator, and a distribution network for supplying the signals sensed to an adaptor to combine instances of the sensed uplink signal in a manner that takes into account a Time Division Medium Access scheme and a demodulator to demodulated the combined signal. The system further comprising a downlink subsystem that in turn comprises a modulator for generating a modulated waveform, and an optical fiber distribution network to distribute the modulated waveform to each luminaire in a group. Each such luminaire generates a drive current for driving a lighting element of that luminaire to emit light.

Abstract: An LED module (200) comprising: a first set of LEDs (D1) for emitting illumination to illuminate an environment, arranged within a first circuit path; a second set of one or more LEDs (D2) for emitting light, arranged within a second circuit path; both the first and second sets being powered by a portion of the power received via a same pair of input terminals, and the first circuit path being longer than the second circuit path; and filter circuitry (206, 208) arranged to filter a modulation in the power received via the terminals, the filtering comprising allowing a component of the modulation at a predetermined modulation frequency to be passed only to the second set of LEDs (D2) and not the first set (D1), thereby causing a corresponding signal to be embedded in the light emitted by the second set but not in the illumination emitted by the first set.