摘要:
In order to compensate for chromatic dispersion caused by optical fiber transmission in a communication system with coherent detection using optical signals, specific frequency band signals are used to enable estimation of a chromatic dispersion value. The chromatic dispersion value calculating apparatus is provided with: a signal distributing circuit which distributes, into a plurality of signal sequences, an electrical digital signal converted from received optical signals of an optical signal transmitted by an optical signal transmitting apparatus, in which a known signal with concentrated frequency components of a plurality of specific frequencies is appended to a signal generated from a transmission data sequence; a plurality of frequency band pass filter circuits, each of which separating only each of a plurality of specific frequency components in which the known signal is included from each of the signal sequences distributed by the signal distributing circuit, and passing each of the specific frequency components therethrough; a plurality of power calculating circuits which are provided so as to correspond respectively to the plurality of frequency band pass filter circuits and which calculate power values of signals output from the corresponding frequency band pass filter circuits; a delay time calculating circuit which detects times at which power has the maximum value or times at which the power exceeds a predetermined threshold value, respectively from signal sequences of the power values output from the plurality of power calculating circuits, and which compares the detected times; and a chromatic dispersion value calculating circuit which calculates a chromatic dispersion value based on a comparison result of the times by the delay time calculating circuit.
摘要:
A transmission apparatus repeatedly inserts reference signal sequences into a transmission signal sequence at different timings, and converts the transmission signal sequence, into which the reference signal sequences are inserted, into an optical signal. The reception apparatus includes a detection unit, a waveform equalization unit, and a signal quality measurement unit. The detection unit receives the optical signal transmitted through an optical transmission line, and converts the received optical signal into a reception signal of an electrical signal. The waveform equalization unit performs waveform equalization on the reception signal converted into the electrical signal. The signal quality calculation unit extracts a reception signal sequence set in each section corresponding to the reference signal sequence from the received signal on which waveform equalization performed. For each combination of different sections, the signal quality calculation unit calculates a mean square error between the mean of the reception signal sequences set in the sections included in a combination and the reference signal sequence, and calculates a signal-to-noise ratio and a signal-to-distortion ratio of the reception signal using the mean square error calculated for each combination.
摘要:
Information on allocation of a bandwidth of uplink communication of each of user devices is extracted from information notified from an upper-level device on the uplink communication of the user devices. Correspondence information is created to indicate a correspondence among the upper-level device, the terminal device, the lower-level device, and the user device. A start time point of the uplink communication of the terminal device and an information amount of signals for which transmission of the uplink communication of the terminal device is allowed are allocated to the terminal device on the basis of the information on allocation of the bandwidth of the uplink communication of each of the user devices and the correspondence information.
摘要:
Information on allocation of a bandwidth of uplink communication of each user device is extracted from information notified by an upper-level device on the uplink communication of the user devices. Identification information of a lower-level device connected to a terminal device and identification information of the user devices are stored in correlation with each other. A bandwidth demanded for uplink communication of the terminal device is determined on the basis of the information on the allocation of the bandwidth of the uplink communication of each of the user devices and the identification information of the user devices. A start time point of the uplink communication of the terminal device and the amount of information of signals for which transmission of the uplink communication of the terminal device is allowed are allocated to the terminal device on the basis of the bandwidth demanded for the uplink communication of the terminal device.
摘要:
One aspect of the present invention is an optical transmission system including a transmitter connected to a transmission line having M spatial channels, and a receiver that receives a signal transmitted from the transmitter via the transmission line, wherein the transmitter includes: an allocator that allocates a transmission bit string transmitted to the transmission line into a bit string serving as a basic signal and a bit string serving as spatial channel information; a generator that generates N (M>N) signals from the bit string serving as the basic signal allocated by the allocator; and a selector that selects N spatial channels, through which the N signals generated by the generator are transmitted, from the M spatial channels on the basis of the bit string serving as the spatial channel information allocated by the allocator.