Central unit and remote unit

A central unit, comprising:

• a plurality of digital-to-analog converters (DACs), wherein each DAC is configured to convert a digital electrical signal into an analog electrical signal;
• a plurality of first electro-optical converters corresponding to the plurality of DACs, wherein each first electro-optical converter is configured to:
• obtain the analog electrical signal output by the corresponding DAC, and convert the analog electrical signal into an analog optical signal;
• a plurality of first optical processors corresponding to the plurality of first electro-optical converters, wherein each first optical processor is configured to:
• obtain the analog optical signal output by the corresponding first electro-optical converter, and output an analog optical signal processed by the first optical processor, and wherein the first optical processor comprises at least one of:
• at least one first optical filter, at least one first optical phase shifter, and at least one first optical power amplifier;
• a first multiplexer, wherein the first multiplexer is configured to combine a plurality of analog optical signals output by the plurality of first optical processor into one analog optical signal;
• a first demultiplexer, wherein the first demultiplexer is configured to decompose the one analog optical signal into a plurality of analog optical signals at different wavelengths;
• at least one first optical-electrical converter, wherein the first optical-electrical converter is configured to convert an analog optical signal at one wavelength into an analog electrical signal;
• and
• at least one analog-to-digital converter (ADC), wherein the ADC is configured to convert the analog electrical signal output by the first optical-electrical converter into a digital electrical signal.