A master station device is connected to a slave station device that emits a transmission signal received by light via an optical transmission path from a plurality of antenna elements. The master station device includes an optical signal output unit that outputs optical signals of a plurality of wavelengths, a phase adjustment unit that adjusts, for each wavelength, a phase of the transmission signal based on phase rotation that the optical signal is to undergo while being transmitted through the optical transmission path and a phase in one of the antenna elements corresponding to the wavelength of the optical signal, an optical modulation unit that modulates, for each wavelength, the optical signal output by the optical signal output unit with the transmission signal the phase of which is adjusted in accordance with the wavelength of the optical signal, and an optical combining unit that multiplexes the optical modulated signal of each wavelength and outputs the multiplexed signal to the optical transmission path. The slave station device includes an optical demultiplexing unit that demultiplexes the optical modulated signal transmitted through the optical transmission path and an optical/electric conversion unit that outputs the transmission signal obtained by converting the optical modulated signal of each wavelength into an electric signal to one of the plurality of the antenna elements corresponding to the wavelength.

Systems and methods for reducing the variation in the power of optical signals transmitted in an upstream direction, at the inputs of an active combiner in an RFoG CATV architecture preferably configured to reduce optical beat interference, so as to increase the dynamic range of a laser in the active combiner.

In one embodiment, a host-to-host network comprises: first host units (HUs) located at a first end and configured to output optical output signals and receive optical input signals; second HUs located at a second end and configured to output optical output signals and receive optical input signals; a first optical WDM configured to combine the first HU optical output signals and output a corresponding first combined output over a first fiber; a second optical WDM configured to receive the first combined output and demultiplex the optical output signals and provide them as optical input signals for the second HUs; the second optical WDM configured to combine second HU optical output signals and output a corresponding second combined output over a second fiber; the first optical WDM configured to receive the second combined output and demultiplex the optical output signals and provide them as optical input signals for the first HUs.

A master station device is connected to a slave station device that emits a transmission signal received by light via an optical transmission path from a plurality of antenna elements. The master station device includes an optical signal output unit that outputs optical signals of a plurality of wavelengths, a phase adjustment unit that adjusts, for each wavelength, a phase of the transmission signal based on phase rotation that the optical signal is to undergo while being transmitted through the optical transmission path and a phase in one of the antenna elements corresponding to the wavelength of the optical signal, an optical modulation unit that modulates, for each wavelength, the optical signal output by the optical signal output unit with the transmission signal the phase of which is adjusted in accordance with the wavelength of the optical signal, and an optical combining unit that multiplexes the optical modulated signal of each wavelength and outputs the multiplexed signal to the optical transmission path. The slave station device includes an optical demultiplexing unit that demultiplexes the optical modulated signal transmitted through the optical transmission path and an optical/electric conversion unit that outputs the transmission signal obtained by converting the optical modulated signal of each wavelength into an electric signal to one of the plurality of the antenna elements corresponding to the wavelength.

The present disclosure provides a data transceiving method, a data transceiving device, a wavelength configuration method and a wavelength configuration device. The data transceiving method includes that a first optical module receives control information sent by a second optical module; the first optical module adjusts transmission and receiving wavelengths according to the control information; and the first optical module executes transmission and receiving of data with the second optical module according to the adjusted transmission and receiving wavelengths.

A fixed wireless access network provides for high-frequency data links between aggregation nodes and endpoint nodes. The system further provides for lower frequency wireless data links, which have carrier frequencies less than high-frequency wireless data links. These lower frequency links provide for auxiliary communications between the aggregation nodes and one or more endpoint nodes. During normal operation, the nodes exchange packet data via the high-frequency data links. However, when impairment of the high-frequency data links is detected, the nodes direct the packet data over the low-frequency data links instead until the high-frequency data links are no longer impaired.

A derivation method is a derivation method performed by a communication system, including: a transmission step of transmitting a first radio-wave signal according to an optical signal with a first wavelength and a second radio-wave signal according to an optical signal with a second wavelength; a communication start time information acquisition step of acquiring information on a first communication start time and information on a second communication start time; a reception time information acquisition step of acquiring information on a first reception time that is a reception time related to the first radio-wave signal, and information on a second reception time that is a reception time related to the second radio-wave signal; and an optical fiber length derivation step of deriving a length of the optical fiber, based on the first communication start time, the first reception time, the second communication start time, the second reception time, a group velocity or a group delay time of the optical signal with the first wavelength, and a group velocity or a group delay time of the optical signal with the second wavelength.

Provided is an optical transmitting and receiving system. The optical transmitting and receiving system may include: a Main Hub Unit (MHU) configured to perform wavelength division multiplexing on a plurality of downlink signals using a plurality of wavelengths and transmit the multiplexed downlink signal through a first optical cable; a first Remote Optical Unit (ROU) configured to perform demultiplexing on the multiplexed downlink signal received from the MHU and output a part of the plurality of downlink signals; and a second ROU configured to perform demultiplexing on the multiplexed downlink signal and output other part of the plurality of downlink signals.

Methods, systems, and devices for a decision directed multi-modulus searching algorithm are described. A receiver may receive an optical signal including a set of data symbols. The receiver may iteratively determine a set of centroids for demodulating the set of data symbols (e.g., as part of a training procedure). The centroids may be used to demodulate the set of data symbols according to a modulation constellation associated with the set of data symbols. The training procedure may include, for each data symbol of a subset of data symbols, assigning a centroid of the set of centroids to each data symbol and updating the set of centroids based on assigning the centroid to each data symbol. The receiver may demodulate the set of data symbols based on the updated set of centroids.

A network or system in which a hub or primary node may communicate with a plurality of leaf or secondary nodes. The hub node may operate or have a capacity greater than that of the leaf nodes. Accordingly, relatively inexpensive leaf nodes may be deployed to receive data carrying optical signals from, and supply data carrying optical signals to, the hub node. One or more connections may couple each leaf node to the hub node, whereby each connection may include one or more spans or segments of optical fibers, optical amplifiers, optical splitters/combiners, and optical add/drop multiplexer, for example. Optical subcarriers may be transmitted over such connections, each carrying a data stream. The subcarriers may be generated by a combination of a laser and a modulator, such that multiple lasers and modulators are not required, and costs may be reduced. As the bandwidth or capacity requirements of the leaf nodes change, the number of subcarriers, and thus the amount of data provided to each node, may be changed accordingly. Each subcarrier within a dedicated group of subcarriers may carry OAM or control channel information to a corresponding leaf node, and such information may be used by the leaf node to configure the leaf node to have a desired bandwidth or capacity.