Systems and methods for OFDM duobinary transmission

A method of modulating, by a transmitter, a series of input digital symbols of a first modulation scheme, comprising the steps of:

• receiving a sequential series of samples of the digital symbols in a frequency domain of the first modulation scheme, such that its dual is a second modulation scheme in a time domain;
• applying a 90 degree rotational operation to the second modulation scheme to generate a rotational modulation format, wherein the 90 degree rotational operation is a Fast Fourier transform;
• modulating the series of digital symbols with the generated rotational modulation format;
• and
• outputting the modulated series of digital symbols to a receiver.

A digital transmission system, comprising:

• a transmitter configured to transmit an input series of complex symbols;
• a duobinary encoder in communication with the transmitter, and configured to receive the input series of complex symbols and output a partial response signaling (PRS) signal;
• a converter in communication with the duobinary encoder, and configured to (i) convert the PRS signal output into the time domain, and (ii) construct a duobinary OFDM signal for transmission by splitting a subcarrier of the input series of complex symbols to appear over two adjacent frequency domain subcarriers;
• and
• a receiver for receiving the time domain-converted PRS signal from the transmitter over a signal path.