The disclosure provides methods, apparatus and computer-readable media for synchronization over an optical network. A method comprises: receiving, from a client, a request to initiate a synchronization service for a client node coupled to the optical communication network; and, in response to the request, establishing a synchronization service to the client node via a virtual synchronization network utilizing the optical communication network. The synchronization service utilizes a bidirectional optical channel established via the optical communication network for the transmission of synchronization data for the client.

A method and system for multipulse-pulse position modulation optical transmission that includes selecting a multipulse-pulse position modulation having a symbol alphabet having an upper-bound symbol alphabet size, and determining, based on at least one transmission characteristic associated with a transmitter, a subset of symbols of the selected symbol alphabet capable of being transmitted by the transmitter, the subset of symbols having a set of binary codewords. The method and system may include identifying two-symbol concatenation of binary codewords in the set of binary codewords, calculating a cross correlation of binary codeword in the set of binary code words through every two-symbol concatenation, determining a set of one or more acceptable codeword combinations by eliminating a portion of two-symbol concatenation of codewords corresponding to overlapping peaks in the respective calculated cross correlations, and transmitting, by the transmitter via an optical communication channel, information encoded based on the determined acceptable codeword combinations.

Provided is a transmission circuit with which it is possible to facilitate error correction of burst errors without increasing the processing load in multiframes configured from a plurality of OTN frame signals. This transmission circuit is provided with: a transmission-side signal recognition unit for detecting MFAS and recognizing the order of N number of OTN frame signals; an intra-multiframe sequence conversion unit for converting the sequence of data signals inside the multiframe in response to the recognized order; a transmission-side rearranging unit for consolidating the sequentially converted data signals into lengths equal to those of the OTN frame signals and creating N number of quasi-OTN frame signals; and a transmission unit for transmitting the multiframes configured from the N number of quasi-OTN frame signals.

An optical system is provided comprising a first node and a channel drop add device. The first node is configured to transmit data onto an optical fiber in a first line direction. The channel drop add device (501) is adapted to receive and add channels onto the optical fiber thereby transmitting the data into the first and a second line direction. The network further comprises a second node configured to form a transmitter/receiver function. The second node is configured to receive data on said optical fiber from said first and second line directions. Further, the second node is adapted to synchronize received data from said first and second line directions by delaying the data signals seeing the shortest delay, by a delay device.

A synchronizer for synchronizing transfer over an optical link includes a frequency reference oscillator; a tracking optical timing source; a tracking comb signal; a signal processor-controller; a comb timing discriminator; a clock frequency comb; a bidirectional terminal; a time-frequency offset measurement system; and a second comb timing discriminator.

An apparatus and method for providing a differential latency, DL, between an upstream, US, transmission and a downstream, DS, transmission via an optical transmission link (OTL), said apparatus comprising a measurement unit (2) configured to measure the round trip delays, RTD, of at least two measurement signals having different measurement wavelengths; and a processing unit (3) configured to derive an upstream, US, delay of at least one optical signal at an upstream wavelength from the at least two measured round trip delays, RTD, and to derive a downstream, DS, delay of at least one optical signal at a downstream wavelength from the at least two measured round trip delays, RTD, wherein the differential latency, DL, is calculated on the basis of the derived delays, RTD.

An optical transceiver is configured to receive an optical signal on which a monitoring signal encoded by Manchester encoding is superimposed. The optical transceiver includes a decoding circuit configured to decode the monitoring signal from an electrical signal generated from the optical signal. The decoding circuit includes an interval measuring unit and a decoding unit. The interval measuring unit is configured to detect only a rising edge or a falling edge of a waveform of the electrical signal, to measure a first time interval between a detected first edge and a second edge detected immediately after detecting the first edge, and to measure a second time interval between the second edge and a third edge detected immediately after detecting the second edge. The decoding unit is configured to decode the monitoring signal encoded by the Manchester encoding based on a ratio between the first and second time intervals.

A method for synchronizing a data frame and data symbols in a communication system includes generating a training sequence including a serial sequence of data symbols that are conjugate symmetric, inserting the training sequence in a transmitter-side data frame, converting constituent data symbols of the transmitter-side data frame to communication signals, transmitting the communication signals from a transmitter to a receiver, converting the communication signals to a stream of received data symbols, detecting presence of the training sequence in the stream of received data symbols, and identifying a position of a received data frame from the presence of the training sequence.

An optical wireless transmission system 10 includes a transmission device including at least one memory storing instructions, and at least one processor configured to execute the instructions to; generate a plurality of digital outphasing signals; orthogonally modulate the digital outphasing signals at an intermediate frequency; and set an intermediate frequency for satisfying a specified signal-to-distortion power ratio based on a sampling frequency, wherein the digital outphasing signals are orthogonally modulated at the intermediate frequency; a hardware optical fiber module configured to convert orthogonally modulated digital electrical signals into optical signals, transmit the optical signals through an optical fiber, and convert the optical signals into digital electrical signals; and a remote unit configured to combine the digital electrical signals transmitted by the hardware optical fiber module, and transmit a combined signal as a radio signal.

A modulation device includes a modulator circuit that causes a light source to perform light communication, storage storing an internal ID, and a control circuit that determines whether an external ID is input into the modulation device. When the control circuit determines that the external ID is input into the modulation device, the control circuit causes the input external ID to be input, as a modulation signal, into the modulator circuit. When the control circuit determines that the external ID is not input into the modulation device, the control circuit causes the internal ID stored in the storage to be input, as a modulation signal, into the modulator circuit.