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US 2018/0294880 A1Published application
System and method for coherent detection with digital signal procession
AssigneeZTE (USA) Inc.
InventorsJIANJUN YU, Jianqiang Li, Hung-Chang Chien, Zhensheng Jia
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Abstract
Methods and apparatus to realize high spectral efficiency in optical signals transmitted over long distances.
Claims20
A method of generating a wide bandwidth multiplexed optical signal and transmitting it over an optical fiber, the method comprising:
- generating, by a laser, a continuous lightwave;
- generating, from the continuous lightwave, a multicarrier signal having a fixed channel spacing of f GHz;
- separating the multicarrier signal into a plurality of optical subcarriers;
- routing each of the optical subcarriers to a respective I/Q modulator and modulating each of the subcarriers to carry f Gbaud of data as a QPSK signal by the corresponding I/Q modulator;
- combining, in an optical multiplexer, the modulated optical subcarriers into a multiplexed optical signal;
- and
- transmitting the multiplexed optical signal with no synchronization information over an optical fiber, so that blind data detection is required at the receiving end of the communication.
4 more elements
A method of blind detecting of data contained in a wide bandwidth multiplexed optical signal transmitted over optical fiber, the method comprising:
- receiving, by a coherent optical receiver, a wide bandwidth multiplexed optical signal from an optical fiber;
- applying a local oscillator having a frequency substantially equal to a subchannel spacing f of the received multiplexed optical signal to the received multiplexed optical signal to obtain a plurality of subcarriers;
- polarization demultiplexing an X signal and a Y signal from each of the subcarriers;
- demultiplexing an in phase (I) signal and a quadrature phase (Q) signal from each of the X and Y signals;
- and
- coherently detecting data carried by each of the I and Q signals using:
- an ADC with a bandwidth of about 0.5 f;
- a signal sampler with a sampling frequency of about 1.5 f;
- and
- a digital signal processor DSP configured to:
- condition the sampled signals;
- and
- apply maximum likelihood sequence estimation (MLSE) to the conditioned signals to estimate data carried on each of the I and Q signals.
10 more elements
An apparatus for detecting data contained in an optical signal received from an optical transmission fiber, comprising:
- a local oscillator having a frequency substantially equal to a subchannel spacing f separating a plurality of subchannels containing in the received optical signal, to obtain a plurality of subcarrier signals;
- a polarization demultiplexer to obtain an X signal and a Y signal from each of the subcarrier signals;
- an OFDM demultiplexer to obtain an in phase (I) signal and a quadrature phase (Q) signal from each of the X and Y signals;
- an ADC with a bandwidth of about 0.5 f;
- a signal sampler with a sampling frequency of about 1.5 f;
- and
- a digital signal processor DSP configured to condition the sampled signals and apply maximum likelihood sequence estimation (MLSE) to the conditioned signals to estimate data carried on each of the I and Q signals.
4 more elements
Dependencies are inferred from the claim text.