A reception apparatus includes a detection unit that detects occurrence of a phase slip in phase estimation values of time-series received symbol data, and determines an inclination of the phase slip, a delay processing unit that generates first received signal data obtained by delaying received signal data obtained from the time-series received symbol data by one symbol time interval, a phase shift unit that generates second received signal data by performing phase shift according to the inclination, only in a period in which one symbol time interval elapses, on only the received signal data of a symbol time at which the occurrence of the phase slip is detected among pieces of the received signal data, and a remainder processing unit that derives a remainder of a difference between the second received signal data and the first received signal data.

A technique is provided for transmitting client data included in a client signal via an optical transmission path of an optical transport network. The optical transport network uses transport frames include a transport frame period for transmitting client data. The method includes receiving multiple client entities comprising multiple client data bits; determining the number of client data entities received during a transport frame period to establish a mean number of client data entities to be included in a transport frame, the mean number of client data entities corresponding to a mean number of client data bits; mapping multiple client data entities into the transport frame wherein mapping comprises alternately adding and subtracting an amount of client data bits to/from the mean number of client data bits for at least two consecutive transport frames; and transmitting the transport frames comprising the client data via the optical transport network.

A data processing method and a device, the method including determining, by an optical network unit, in a received data stream, after the optical network unit enters a pre-synchronization state, a position of a forward error correction (FEC) codeword boundary in the data stream based on a position of a physical synchronization sequence (Psync) field, performing an FEC codeword decoding check, where the Psync field is a field that matches a preset Psync, in the data stream, and entering, by the optical network unit, a synchronization state in response to an FEC codeword among N consecutive FEC codewords in the data stream passing the decoding check, where N is an integer greater than or equal to 1.

Techniques, methods and system, for synchronization of sparse data signals are disclosed, comprising mixing a serial stream of sparse data signals with a serial stream of synchronization signals, to thereby add redundancy to the serial stream of sparse data signals and enable clock regeneration from a serial stream of mixed signals produced by said mixing, emulating the serial stream of synchronization signals by applying the clock regeneration to the serial stream of mixed signals, and generating a stream of parallel synchronization signals having a frequency of the serial stream of synchronization signals, deserializing the serial stream of mixed signals into a stream of parallel mixed signals having a data rate lower than a data rate of the serial signal streams, and demixing the stream of parallel synchronization signals with the stream of parallel mixed signals and thereby removing the redundancy introduced by the mixing into the sparse data signals and generating a parallel stream of demixed signals substantially synchronized with said synchronization signals.

Synchronizing a pulse position modulation (PPM) signal. A method includes performing a first synchronization operation by receiving a first series of symbols. The symbols in the first series are transmitted with a pulse in a known slot, such that the symbols comprise pulses that are substantially equally spaced in time from adjacent symbols. The first synchronization operation includes identifying when each pulse is received for each of the symbols and using information identifying when each pulse is received for each of the symbols in the first series of symbols to identify symbol and slot boundaries for the pulse position modulation signal. The method further includes performing a second synchronization operation by receiving a second series of symbols transmitted in a known pattern, and identifying the known pattern in the received second series of symbols to identify a frame boundary.

[Problem] To determine a time difference between clocks which, for example, are placed far apart from each other with high accuracy at low cost. [Solution] In a time comparison system 20, an intermediate station 21 disperses a single optical signal 21c in the spatial region using the optical complex amplitude modulation to simultaneously transmit the optical signal 21c to a plurality of comparative stations 22 and 23 apart from each other. The intermediate station 21 transmits the optical signal 21c while changing the transmission angle using phase modulation, performs intensity scanning for the reflected light c1 of the optical signal 21c, and detects the peak intensity to determine the directions of the comparative stations 22 and 23. The reflected light c1 of the optical signal 21c transmitted to the comparative stations 22 and 23 of which the direction have been determined, is detected to determine a round-trip propagation delay time between the intermediate station 21 and each of the comparative stations 22 and 23. The difference calculation unit 25 calculates a sum of time difference between each of times to and tb associated with the comparative stations 22 and 23 and the time tc associated with the intermediate station 21, and the determined propagation delay time to determine time information of each of the comparative stations 22 and 23. Based on the result of subtracting, from the time information of the comparative stations 22, the time information of the comparative stations 23, the time difference between the comparative stations 22 and 23 is determined.

A data transmission method includes receiving, by an optical line terminal (OLT) from an optical network unit (ONU), uplink burst data that includes a synchronization data block and a payload, where the synchronization data block includes first synchronization data, wherein the first synchronization data includes a first preamble and an ONU identifier, and a first bandwidth occupied by the first frequency distribution of the first synchronization data is narrower than a second bandwidth occupied by the second frequency distribution of the payload, and obtaining, by the OLT from the first synchronization data, the ONU identifier.

A method for performing ONU Management and Control Interface (OMCI) synchronization includes receiving an OMCI message containing a OLT-G entity identifying OLT's vendor identification (ID) and version. The method also includes determining if an OLT vendor identification (ID) matches with a current vendor ID and if an Optical Line Terminal (OLT) version is compatible with current OMCI handlers. When the OLT vendor ID fails to match with the current vendor ID, automatically performing a OMCI handler switching process. The OMCI handler switching process includes setting a current OLT vendor as a new OLT vendor ID, deleting a OMCI configuration previously stored in the flash memory after setting the new OLT vendor ID, and rebooting the ONT to allow the ONT to initialize a OMCI configuration using a new OMCI profile.

Systems and methods for operating a quantum network system. The methods comprise, by a network node: generating optical clock pulses and photons using the optical clock pulses; generating a combined signal by combining the optical clock pulses with at least some of the photons such that a consistent temporal offset exits between the optical clock pulses and the first photons and/or a wave function of each photon at least partially overlaps an envelope of a respective one of the optical clock pulses; and transmitting the combined signal over a first quantum channel in which the optical clock pulses co-propagate with the photons.

An optical transmission device includes: a first receiver circuit, a second receiver circuit, a switch circuit, a terminator circuit, a packet buffer, a clock generator, and a signal generator. The first receiver circuit converts an optical signal received via a first route into a first electric signal. The second receiver circuit converts an optical signal received via a second route into a second electric signal. The switch circuit selects the first electric signal or the second electric signal. The terminator circuit extracts a packet from an electric signal selected by the switch circuit. The packet buffer stores the packet extracted by the terminator circuit. The clock generator generates a clock signal. The signal generator generates a continuous signal that includes the packet stored in the packet buffer by using the clock signal.