A communication device of the disclosure includes a phase synchronizer, a modulator, and a controller. The phase synchronizer generates a second signal on a basis of a first signal received from a communication partner by selectively performing one of a closed loop operation and an open loop operation. The modulator is able to modulate the first signal on a basis of the second signal. The controller controls operations of the phase synchronizer and the modulator.

An optical transceiver is provided with an optical front end for receiving signal light comprising an optical sub-channel, and for providing an electrical signal based on the signal light; a light source optically coupled to the optical front end for providing local oscillator light thereto for mixing with the signal light; an electro-optical modulator coupled to the light source for receiving output light therefrom and for modulating the output light with digital information to obtain modulated light; and a signal processor operably coupled to the optical front end. The signal processor is configured for processing the electrical signal to obtain a frequency offset of the sub-channel; and adjusting an optical frequency of the modulated light based on the frequency offset. When applied to a multiple-access environment, this may allow access nodes to generate optical sub-channels in the uplink direction using the downlink optical signal as an optical frequency reference.

Techniques are disclosed for determining a light-based communication (LCom) receiver position. The techniques can be used to determine the position of a receiver relative to a specific luminaire within the field of view (FOV) of the receiver camera. The relative position may be calculated by determining the distance and the orientation of the receiver relative to the luminaire. The distance relative to the luminaire may be calculated using the observed size of the luminaire in an image generated by the receiver camera, the image zoom factor, and actual geometry of the luminaire. The orientation relative to the luminaire may be determined using a fiducial associated with the luminaire that can be used as an orientation cue. Once the position of a receiver relative to a luminaire is determined, the absolute position of the receiver may be calculated using the absolute position of the luminaire.

The disclosure is directed to a method and system for generating a pilot tone for an optical signal with an optical telecommunications system. The pilot tone is generated in the digital domain by modulating the data to be transmitted to a destination node within the optical telecommunications network. The modulation of the data introduces occurrence modulation to the optical signal.

The present disclosure discloses a method and an apparatus for hybrid multiplexing/de-multiplexing in a passive optical network, the method comprising steps of: dividing N first intermediate frequency sub-bands averagely into M clusters, wherein each of the clusters contains K first intermediate frequency sub bands and N=M*K, and wherein each of the K first intermediate frequency sub-bands carries a baseband digital electrical signal; selecting, by a software defined first intermediate frequency multiplexer, the baseband digital electrical signals of K first intermediate frequency sub-bands from the N first intermediate frequency sub-bands for software defined frequency division multiplexing and forming a cluster; and frequency division multiplexing, by an analog hardware cluster multiplexer, analog electrical signals of the M clusters on a second intermediate frequency sub-band. The hybrid analog radio over fiber scheme according to the present disclosure achieves the balance between the software defined intermediate frequency multiplexer and the hardware cluster multiplexer and multi-stage frequency division multiplexing, and has very high cost effectiveness and configuration flexibility.

Techniques are disclosed for providing proper raster line alignment of a camera or other light-sensing device of a receiver device relative to a transmitting light-based communication (LCom)-enabled luminaire to establish reliable LCom there between. In accordance with some embodiments, proper alignment can be provided automatically (e.g., by the receiver device and/or other suitable controller). In accordance with some embodiments, proper alignment can be provided by the user. In some instances in which a user is to be involved in the alignment process, the receiver device may be configured, for example, to instruct or otherwise guide the user in the process of properly aligning the receiver device relative to a given transmitting LCom-enabled luminaire.

Techniques are disclosed for providing light-based communication (LCom) between a receiver device and one or more transmitting LCom-enabled luminaires. In accordance with some embodiments, LCom data to be transmitted may be allocated over multiple colors of light output by multiple LCom-enabled luminaires and transmitted in parallel across the multiple colors of light using a time division multiple access (TDMA) scheme. In some cases, the disclosed techniques can be used, for example, to allow for multiple LCom-enabled luminaires to communicate simultaneously over multiple active LCom channels with a single receiver device. In some instances, the disclosed techniques may be used, for example, to provide channel redundancy that facilitates successful completion of LCom data transmission when an LCom channel is broken. In some instances, the disclosed techniques may be used, for example, to provide more accurate positioning for indoor navigation.

Techniques are disclosed for coding light-based communication (LCom) data in a manner that allows for detection thereof, for example, via a standard low-speed (e.g., 30 frames per second) smartphone camera. In accordance with some embodiments, the disclosed techniques can be used, for example, in encoding and decoding LCom data in a manner that: (1) prevents or otherwise minimizes perceivable flicker of the light output by a transmitting LCom-enabled luminaire; and/or (2) avoids or otherwise reduces a need for additional, specialized receiver hardware at the receiver computing device including the camera. In some cases, the disclosed techniques can be used, for example, to enhance the baud rate between a transmitting LCom-enabled luminaire and a receiver device.

Embodiments may provide a way of communicating via an electromagnetic radiator, or light source, that can be amplitude modulated such as light emitting diode (LED) lighting and receivers or detectors that can determine data from light received from the amplitude modulated electromagnetic radiator. Some embodiments may provide a waveform in the form of chips at a chipping clock frequency that switch a light source between on and off states to communicate via light sources that can be amplitude modulated such as LED lighting. Some embodiments may provide a method of transmitting the waveform via modulated LED lighting. Some embodiments are intended for indoor navigation via photogrammetry (i.e., image processing) using self-identifying LED light anchors. In many embodiments, the data signal may be communicated via the light source at amplitude modulating frequencies such that the resulting flicker is not perceivable to the human eye.

A system for generating a frequency modulated linear laser waveform includes a single frequency laser generator to produce a laser output signal. An electro-optical modulator modulates the frequency of the laser output signal to define a linear triangular waveform. An optical circulator passes the linear triangular waveform to a band-pass optical filter to filter out harmonic frequencies created in the waveform during modulation of the laser output signal, to define a pure filtered modulated waveform having a very narrow bandwidth. The optical circulator receives the pure filtered modulated laser waveform and transmits the modulated laser waveform to a target.