A method of an optical sensor device includes: using an oscillator circuit to generate a clock signal; and generating monitoring frames according to the clock signal; wherein the clock signal is calibrated in response to at least one of: a first communication signal, transmitted for multiple times from a monitoring system externally coupled to the optical sensor device, is received by the optical sensor device; a data length of the first communication signal transmitted for only one time from the monitoring system externally coupled to the optical sensor device; and, a data length of an encoded data portion of the first communication signal transmitted for only one time.

A method in which a plurality of transmit signals are generated at data rates that are offset from each other to minimize detectable electromagnetic interference at a particular frequency. The method further includes converting each transmit signal to a corresponding optical transmit signal of a plurality of optical transmit signals for transmission via a corresponding channel of a plurality of channels of an optical network device and transmitting the plurality of optical transmit signals via respective ones of the plurality of channels for transmission on respective optical fibers.

A method for processing low-rate service data, an apparatus, and a system, where the method includes: mapping low-rate service data into a newly defined low-rate data frame, where a rate of the low-rate data frame matches a rate of the low-rate service data, the data frame includes an overhead area and a payload area, the payload area is used to carry the low-rate service data, a rate of the payload area in the low-rate data frame is not less than the rate of the low-rate service data, and the rate of the low-rate service data is less than 1 Gbps; mapping the low-rate data frame into one or more slots in another data frame, where a rate of the slot is not greater than 100 Mbps; mapping the other data frame into an optical transport unit (OTU) frame; and sending the OTU frame.

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.

[Problem] To reduce a time synchronization error caused by upstream and downstream asymmetry of the transmission path, improve wavelength band utilization efficiency, and reduce the required number of transponders.

[Solution] An optical transmission device of each node simultaneously sends a plurality of signals having different wavelengths as delay measurement signals to a transmission path. The optical transmission device determines a delay value that reflects a propagation delay calculated based on an arrival time difference between a plurality of wavelengths in a signal received from another node, and determines a waiting time amount based on the delay value and the propagation delay. The optical transmission device notifies the other node of the delay value. Each optical transmission device outputs the received signal from the other node with a delay of the waiting time amount. The optical transmission device generates an optical intermittent signal obtained by selecting and multiplexing any of time information, the delay measurement signal, and communication information. A reception side extracts a desired multiplexed signal from the received optical intermittent signals.

A method of distance synchronization of a series of remote optical receiver points with an optical transmission point, the method including the steps of: (a) sending an optical timing pulse from the optical transmission point to each of the series of remote optical receiver points and back; (b) determining a round trip time of the timing pulse; and (c) storing an indicative measure of the roundtrip time of the timing pulse and utilising the indicative measure to adjust the timing of signals at the remote optical receiver points to determine the relative reception time of signals received by the series of remote optical receiver points.

Techniques (e.g., method, apparatuses, etc.) for permitting communications, e.g., optical communications are described. In one example, a first communication apparatus for the communication with a second communication device may obtain a channel state information from the reception of one or more reference signals and/or beacon signals from one or more frontends of the second apparatus. The first communication apparatus may transform the channel state information from a frequency domain to a time domain, to obtain a time domain channel state information. The first communication apparatus may encode the time domain channel state information. The first communication apparatus may transmit the time domain channel state information to one or more frontends. The first communication apparatus may transmit channel information for association and updated channel information for network coordination in a contention access period and collision-free period, CFP, respectively.

A frame synchronization apparatus (10) according to this invention includes a multiplication unit (11) configured to multiply a received signal by an inverse complex number of a predetermined synchronization pattern with respect to a predetermined signal point on a complex space diagram for each of a plurality of symbols of the received signal, an addition average unit (12) configured to perform addition averaging of outputs from the multiplication unit for the plurality of symbols of the received signal, and a synchronization determination unit (13) configured to perform coincidence determination of whether an output from the addition average unit (12) falls within a predetermined coincidence determination range of the predetermined signal point, and determine a synchronization state of the frame synchronization based on a result of the coincidence determination. According to this invention, it is possible to provide a frame synchronization apparatus that correctly determines a synchronization state even if an error rate of received symbols is high.

Examples described herein relate to an analog front-end (AFE). The AFE includes a trans-impedance amplifier to receive an input current and generate a pair of the differential voltage signals based on the input current and a reference current. Further, the AFE includes a dynamic voltage slicer to receive the differential voltage signals at input terminals and supply digital voltages at output terminals. The dynamic voltage slicer includes a preamplifier to generate a pair of intermediate voltages based on the differential voltage signals sampled at a predetermined frequency. The dynamic voltage slicer also includes a voltage latch circuit coupled to the preamplifier, wherein the voltage latch circuit is to regenerate a pair of digital voltages based on the pair of the intermediate voltages. Moreover, the AFE includes a logic latch coupled to the dynamic voltage slicer to provide digital output states based on the pair of the digital voltages.

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.