An accommodation station transmission unit modulates light based on an RF signal to generate an optical signal and outputs the generated optical signal, a base station transmission unit demultiplexes the output optical signal for each of wavelengths, outputs the demultiplexed optical signals, converts the demultiplexed optical signals into electrical signals to demodulate the RF signal, outputs the demodulated RF signal, and each of first ports of a matrix operation unit including the plurality of first ports and a plurality of second ports and configured to use each of the first ports as a reference port and perform, on signals obtained by the reference ports, a BFN matrix operation of performing phase changes that are different for each of positions of the reference ports and cause each of phases of signals output from the plurality of second ports to have a linear inclination receives the demodulated RF signal and forms transmission beams in different directions for each of wavelengths by a plurality of transmission antennas emitting the RF signal output by each of the second ports of the matrix operation unit.

A master station device includes a processor that outputs a subcarrier modulation signal, and a transmitter that maps an in-phase (I) component and a quadrature-phase (Q) component of the subcarrier modulation signal to an optical signal to be transmitted to a fronthaul.

A method of RF signal processing comprises receiving an incoming RF signal at each of a plurality of antenna elements that are arranged in a first pattern. The received RF signals from each of the plurality of antenna elements are modulated onto an optical carrier to generate a plurality of modulated signals that each have at least one sideband. The modulated signals are directed along a corresponding plurality of optical channels with outputs arranged in a second pattern corresponding to the first pattern. A composite optical signal is formed using light emanating from the outputs of the plurality of optical channels. Non-spatial information contained in at least one of the received RF signals is extracted from the composite signal.

An operational environment is disclosed herein that includes a cryogenic environment and a signal source. The cryogenic environment includes a signal target, an optical link, signal converter devices, and an electrical link. Outside of the cryogenic environment, the signal source generates an electric signal. An electric-to-optical converter converts the electrical signal into an optical signal. The optical link delivers the optical signal into the cryogenic environment. Inside the cryogenic environment, an optical-to-electrical converter converts the optical signal back into an electrical signal. The optical-to-electrical converter transfers the electric signal to the signal target.

An optical module configured to electrically connect to a host. A linear equalizer performs equalization on a host equalized signal to create a module equalized signal, and a driver configured to present the module equalized signal from the linear equalizer to an optical conversion device at a magnitude suitable for the optical conversion device. An optical conversion device receives the module equalized signal from the driver, converts the module equalized signal to an optical signal, and transmit the optical signal over an optical channel. Also part of the optical module is an interface which communicates supplemental equalizer settings to the host. A memory stores the supplemental equalizer settings which reflect the optical modules effect on a signal passing through the optical module. A controller oversees communication of the supplemental equalizer settings to the host such that the host uses the supplemental equalizer settings to modify host equalizer settings.

A system for correcting phase noise and/or drift, the system includes an optical signal module being capable of amplitude modulating the optical signal while being phase- and/or frequency-shifted. Further, the system includes a beam splitter capable of separating at least backward travelling waves based on polarization. Moreover, a fiber connected to the beam splitter and a polarization rotator capable of changing the polarization of the optical signal are provided. The system has a partially reflecting reflector capable of creating a backward travelling wave as well as a photodiode capable of receiving the backward travelling wave. The photodiode is capable of generating a detection signal used for detecting phase noise and/or drift in the backward travelling wave.

A communication system may an optical signal generator and a signal path. The generator may generate one or more optical local oscillator (LO) signals and an optical frequency comb. Optical paths and an optical demultiplexer may distribute the optical LO signal(s) and the frequency comb to photodiodes in one or more access points. The photodiodes may be coupled to antenna radiating elements. The optical paths may illuminate each photodiode using a signal pair that includes one of the optical LO signals and one of the carriers from the frequency comb. The photodiodes may convey wireless signals using the antenna radiating elements at frequencies given by the differences in frequency between the signals in the signal pairs. The radiating elements may concurrently convey the wireless signals with different external devices at different frequencies, with different devices at the same frequency, and/or with the same device at the same frequency.

A coherent optical receiving apparatus including a polarization optical splitter, a polarization controller, an optical hybrid unit, and a combiner. The polarization optical splitter is connected to an input terminal of the optical hybrid unit, and an output terminal of the optical hybrid unit is connected to the combine. The polarization optical splitter receives signal light and local oscillator light in any polarization mode, decomposes the signal light into a plurality of beams of sub signal light, and decomposes the local oscillator light into a plurality of beams of sub local oscillator light. The optical hybrid unit obtains a plurality of beams of hybrid light by performing optical hybridization on the sub signal and sub local oscillator lights, the combiner performs conversion on the plurality of beams of hybrid light to obtain and output coherent electrical signals, and the polarization controller controls polarization of the local oscillator light.

A photo-electron fusion switch that can perform optical communications without any trouble, even when nodes of a communication source and a communication partner that are large in transmission capacity are connected, and makes it possible to realize a concentrated arrangement of devices having similar functions and reduce the communication processing time is connected to communication source's information processing devices and communication partner's information processing devices and information processing devices that are each different in transmission speed so as to configure an optical network system. The photo-electron fusion switch includes a network processor of an electronic circuit for controlling packet switch functions, a plurality of optical transmitter/receivers that can support coherent communications and has a photoelectric conversion function capable of transmitting and receiving optical signals different in transmission speed, an optical line switching device, and a plurality of multiplexing/separators. Each multiplexing/separator simultaneously transmits and receives respective optical signals different in transmission speed to and from the nodes via optical waveguides.

An optical wireless communication system and method An optical wireless communication (OWC) system comprises: a multiple input multiple output (MIMO) device configured to provide a plurality of signals each representing a respective data stream; conditioning circuitry configured to receive the plurality of signals from the MIMO device and process the plurality of signals to produce at least one conditioned signal representative of the data stream(s) and suitable for transmission using an OWC transmission device; an OWC transmission device comprising at least one transmitter for transmitting light and configured to be responsive to the at least one conditioned signal to transmit light representative of the data stream(s) using the at least one transmitter.