Fujitsu Corporation

Huijian Zhang

Zhenning Tao

Lei Li

Hisao Nakashima

Shoichiro Oda

Takahito Tanimura

Takeshi Hoshida

Jun Tian

Meng Yan

Jianqiang Li

The present invention discloses a phase imbalance monitoring apparatus, an amplitude imbalance monitoring apparatus, as well as an apparatus incorporating the same. The phase imbalance monitoring apparatus is for use in an apparatus in which imbalance between an I branch signal and a Q branch signal in quadrature to each other is required to be monitored, and is characterized in comprising a preprocessing unit, for performing preprocessing on the I branch signal and the Q branch signal to extract essential information relevant to correlation of the signals; and a correlation unit, for performing correlation processing on the extracted essential information to learn of the phase imbalance between the I branch signal and the Q branch signal.

Phase imbalance monitoring apparatus, amplitude imbalance monitoring apparatus, and apparatus using the same

The present invention discloses a method and apparatus for bit and power allocation and a communication system. The method for bit and power allocation comprises: determining a set of candidate modulation modes for sub-channels; constructing an SNR lookup table according to a predetermined target BER, the SNR lookup table containing a relationship of an SNR and the number of bits corresponding to a modulation mode in the set of candidate modulation modes at the target BER; obtaining normalized SNRs on the sub-channels; initializing the numbers of bits for the sub-channels; initializing powers for the sub-channels according to the numbers of bits for the sub-channels, the normalized SNRs on the sub-channels and the SNR lookup table; and adjusting the numbers of bits and the powers for the sub-channels in accordance with a principle of maximizing power utilization rate, to obtain the result of the bit and power allocation for the sub-channels.

Method and apparatus for bit and power allocation, and communication system

The present application discloses a method for adaptive blind equalization of a PSK signal, an equalizer and a receiver. According to embodiments as provided, a conjugate product of a current output and a precedent output of an FIR filter is calculated, an equalization coefficient is updated using the conjugate product, and then an input signal is filtered using the FIR filter with the updated equalization coefficient. The embodiments as provided is applicable to adaptive blind equalization of any phase shift keying signal including a BPSK signal.

Method for adaptive blind equalization of PSK signal, equalizer and receiver

In present invention, a filter coefficient adjustment apparatus is used in a polarization demultiplexer which demultiplexes the input signals by using filters to obtain demultiplexed output signals, said filter coefficient adjustment apparatus being used for adjusting the coefficients of the filters, wherein said filter coefficient adjustment apparatus comprises: an logarithm partial derivative calculation unit for calculating the logarithm partial derivative value of a target probability density function of the demultiplexed output signals when its self-variable value is the present demultiplexed output signal value; a gradient calculation unit for calculating the gradient of a target optimizing function for optimizing the distribution of the multiplexed output signals based on the logarithm partial derivative value calculated by the logarithm partial derivative calculation unit; and a filter coefficient updating unit for updating the coefficients of the filters based on the gradient calculated by the gradient calculation unit.

Filter coefficient adjustment apparatus

This application relates to an apparatus and a method for equalizing chromatic dispersion and a digital coherent optical receiver. The apparatus for equalizing chromatic dispersion comprising: a chromatic dispersion equalizing unit, for compensating chromatic dispersion of an input signal; and an additional time delay removing unit, for removing, in accordance with frequency offset of the input signal, chromatic dispersion equalization time delay generated by the chromatic dispersion equalizing unit.

Apparatus and method for equalizing chromatic dispersion and digital coherent optical receiver

The present invention relates to filter, coherent receiver device and coherent receiving method. The filter is used for converting a partial response signal into a full response signal, wherein the filter uses the following transfer function H(z) with respect to a partial response signal having a transfer function in which A is other item, m and n are integers larger than or equal to 0 but not being 0 at the same time, 0&#x3c;&#x3b1;&#x3c;1.

Filter, coherent receiver device and coherent receiving method

The present invention provides a frequency offset monitoring device and an optical coherent receiver. A low speed frequency offset monitoring device comprises a signal speed lowering section, for lowering the speed of an inputted signal and outputting the speed lowered signal, and a frequency offset monitor, for monitoring frequency offset of the speed lowered signal outputted by the signal speed lowering section.

Frequency offset monitoring device and optical coherent receiver

The present invention discloses a frequency offset detecting apparatus and method for use in a digital coherent optical receiver. The digital coherent optical receiver comprises: a front-end processing section for generating a digital baseband electric signal; an equalizer for performing equalized filtering on the digital baseband electric signal; and the frequency offset detecting apparatus for detecting frequency offset contained in the digital baseband electric signal or frequency offset contained in a signal outputted by the equalizer; wherein the frequency offset detecting apparatus comprises an argument difference obtaining unit, a first subtracter, a second subtracter, a quantizer and an averager, of which the argument difference obtaining unit obtains an argument difference of adjacent symbols in a signal inputted therein; the first subtracter subtracts an output of the averager from the argument difference obtained by the argument difference obtaining unit; the quantizer performs uniform quantization with predetermined intervals on an output of the first subtracter; the second subtracter subtracts an output of the quantizer from the argument difference obtained by the argument difference obtaining unit; and the averager averages an output of the second subtracter.

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Beijing, China

Huijian Zhang