Abstract: An optical wireless communication module comprising a plurality of optical transceivers and a controller, wherein the controller is configured to determine the optical transceivers to be used based on movement information of a UE, to activate the optical transceivers to be used and to deactivate other optical transceivers, such that it consumes less energy without compromising Quality of Service.

Abstract: A mobile object configured for movement in an area equipped with VLC illumination sources comprises a light sensor arranged to detect illumination from at least one of the illumination sources within the view of the light sensor; a computer arranged to determine from the detected illumination (i) a position of the mobile object relative to the at least one illumination source and (ii) the identifier of the at least one illumination source; and a transceiver. The transceiver can receive from another mobile object a message comprising the position of the other mobile object relative to a source of illumination, and the identifier of that source of illumination. From this, the computer determines from its position and the message a distance from the other mobile object. A mobile object which transmits such a message is also envisaged.

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 mobile object configured for movement in an area equipped with VLC illumination sources comprises a light sensor arranged to detect illumination from at least one of the illumination sources within the view of the light sensor; a computer arranged to determine from the detected illumination (i) a position of the mobile object relative to the at least one illumination source and (ii) the identifier of the at least one illumination source; and a transceiver. The transceiver can receive from another mobile object a message comprising the position of the other mobile object relative to a source of illumination, and the identifier of that source of illumination. From this, the computer determines from its position and the message a distance from the other mobile object. A mobile object which transmits such a message is also envisaged.

Abstract: A series of frames is captured by a rolling-shutter camera, each frame capturing an image of a light source which has a periodic message embedded in its light. With a rolling-shutter camera, each line captures a respective sample of the message and each frame captures a respective fragment of the message made up of a respective subsequence of the samples, wherein the message can be reconstructed from the fragments captured over multiple frames. Further, the frame rate of the rolling-shutter camera is dependent on a region of interest (ROI), and the method further comprises evaluating a metric indicative of how long will be required to accumulate enough fragments to reconstruct the message at the current frame rate, and adapting the ROI in dependence on this metric in order to change the frame rate and thereby reduce the number of subsequent frames required to complete the reconstruction of the message.

Abstract: A decoder for decoding a signal modulated into visible light. The decoder performs operations of: receiving a series of frames captured by a camera, each capturing an image of the light source at a different time index; from each frame, sampling a plurality of portions of the frame that capture part of the light source, and thereby, over the series of frames, obtaining a respective temporal series of samples from each respective one of the portions; for each of the plurality of portions, determining a respective value of a property that smooths out temporal variations within the respective series of samples; using the respective value of property to determine a respective equalization to apply to each of the portions in order to correct for a non-uniformity in the light source; and applying the respective equalization to each of the portions and detecting the coded light signal based thereon.

Abstract: A coded visible light receiver comprises: a sensor, a transform module, and an interference cancelling module. The sensor receives light comprising data modulated into the light according to a coding scheme. The transform module is configured to transform the data into a frequency domain representation, representing a band of a spectrum resulting from the data being modulated into the light according to the coding scheme. The interference cancelling module is configured to cancel interference occurring in the band of the data, by determining one or more components in the band that exceed a threshold signal strength and cancelling those components.

Abstract: A device comprising: an input for receiving a signal from a rolling-shutter camera which captures frames by exposing a lines of each frame in sequence, the signal comprising a coded light signal; and a signal processing module arranged to obtain a respective sample of the coded light signal from each of a number of said lines, being a substantially smaller number of the lines than exposed by the camera in each frame. The coded light signal comprises a message having a duration longer than this number of lines, and the message is repeated multiple times with a timing such that a different part of the message is seen by the camera in each of a plurality of different ones of said frames. The signal processing module is configured to time align the different parts of the message from the plurality of different frames, and reassemble the message from the time-aligned parts.

Abstract: The visible illumination emitted by each of some or all of an arrangement of contiguously-mounted lighting units is temporally modulated to embed a different respective signal into the illumination emitted by each. A camera captures one or more images of the data-transmitting luminous areas of one or more of these lighting units, from which are detected the respective signals. The system is further configured to spatially modulate at least part of the light emitted by one or more of the lighting units of the arrangement with a spatial pattern. The detection comprises distinguishing each of the one or more data-transmitting lighting units from amongst the multiple data-transmitting lighting units based on an auto correlation of the spatial pattern.

Abstract: A Wiener filter for equalizing an effect of a first filter on an input signal which is subject to the first filter and to noise and/or interference, wherein: the first filter is dependent on at least one unknown quantity; and the Wiener filter is configured based on an averaged representation of the first filter averaged over the at least one unknown quantity, in place of a representation of the first filter being assumed to be known.

Abstract: A coded light signal is embedded into visible light emitted from the light source, to be received by a rolling-shutter camera which captures frames (16) by exposing a plurality of lines (18, 24) of each frame in sequence, the camera having an exposure time with each line being exposed for the exposure time. The coded light signal is formatted according to a format whereby the coded light signal comprises at least one message and the message is repeated multiple times with a timing such that, when samples of the coded light signal are obtained from a substantially smaller number of lines (24) than exposed by the camera in each frame and the message is longer than this number of lines, a different part of the message is seen by the camera in each of a plurality of different ones said frames.

Abstract: A coded light receiver comprising a sensor for receiving coded light, a filter, and a timing and data recovery module. The coded light comprises a signal whereby data and timing are modulated into the light according to a self-clocking coding scheme. The filter is arranged to match a template waveform of the coding scheme against the received signal, thereby generating a pattern of filtered waveforms each corresponding to a respective portion of the data, and the timing and data recovery module recovers the timing from the signal based on characteristic points of the filtered waveforms. The timing and data recovery module is configured to do this by separating the filtered waveforms into different sub-patterns in dependence on the data, and to recover the timing by processing each of the sub-patterns individually based on the characteristic points of each sub-pattern.

Abstract: A device comprising: an input for receiving a signal from a rolling-shutter camera which captures frames by exposing a lines of each frame in sequence, the signal comprising a coded light signal; and a signal processing module arranged to obtain a respective sample of the coded light signal from each of a number of said lines, being a substantially smaller number of the lines than exposed by the camera in each frame. The coded light signal comprises a message having a duration longer than this number of lines, and the message is repeated multiple times with a timing such that a different part of the message is seen by the camera in each of a plurality of different ones of said frames. The signal processing module is configured to time align the different parts of the message from the plurality of different frames, and reassemble the message from the time-aligned parts.

Abstract: The invention relates to an information encoder, and decoder, a signal and a method of encoding and decoding of information for a coded light system. The invention aims to provide amongst others a method for transmitting and receiving a message (msg1, . . . , msg6) in a system for visible light communication and wherein the message comprises a plurality of source symbols and wherein the method for transmitting comprises: generating a modulation signal by mapping the source symbols of the message onto channel symbols for modulating the output of the light source, wherein the message is partitioned into a plurality of packets (d1, . . . , d3) of consecutive channel symbols and wherein idle periods (i1, . . .

Abstract: A coded light signal is embedded into visible light emitted from the light source, to be received by a rolling-shutter camera which captures frames (16) by exposing a plurality of lines (18, 24) of each frame in sequence, the camera having an exposure time with each line being exposed for the exposure time. The coded light signal is formatted according to a format whereby the coded light signal comprises at least one message and the message is repeated multiple times with a timing such that, when samples of the coded light signal are obtained from a substantially smaller number of lines (24) than exposed by the camera in each frame and the message is longer than this number of lines, a different part of the message is seen by the camera in each of a plurality of different ones said frames.

Abstract: A Wiener filter for equalizing an effect of a first filter on an input signal which is subject to the first filter and to noise and/or interference, wherein: the first filter is dependent on at least one unknown quantity; and the Wiener filter is configured based on an averaged representation of the first filter averaged over the at least one unknown quantity, in place of a representation of the first filter being assumed to be known.

Abstract: A coded light receiver comprising a sensor for receiving coded light, a filter, and a timing and data recovery module. The coded light comprises a signal whereby data and timing are modulated into the light according to a self-clocking coding scheme. The filter is arranged to match a template waveform of the coding scheme against the received signal, thereby generating a pattern of filtered waveforms each corresponding to a respective portion of the data, and the timing and data recovery module recovers the timing from the signal based on characteristic points of the filtered waveforms. The timing and data recovery module is configured to do this by separating the filtered waveforms into different sub-patterns in dependence on the data, and to recover the timing by processing each of the sub-patterns individually based on the characteristic points of each sub-pattern.

Abstract: The present invention relates to a distributed pilot scheme especially suited for single frequency networks used, for instance, for broadcasting digital TV. In current digital TV standards, e.g. DVB-T, the transmitters in the SFN transmit the exact same signal in the same frequency and at the same time. As a consequence the channel seen by the receiver is the channel created by the SFN characterized by a very long delay spread, which can be challenging to estimate. According to the present invention different, preferably orthogonal, pilot sequences are assigned to different transmitters in the same SFN so that the receiver can estimate the propagation channels from each transmitter to itself independently.