Joint source and LDPC coding based coding modulation for ultra-high-speed optical transport

A method for optical communication, comprising:

• combining joint source coding with low density parity-check (LDPC) channel coding into a nonuniform signaling by mapping low-complexity variable-length prefix codes onto a constellation;
• and
• generating an arbitrary form of the nonuniform signaling where information bits and parity bits are transmitted with different modulation schemes;
• generating a nonuniform constellation with an overall search method to determine a radius of each layer and a relative angle for each layer of the constellation, wherein a constellation structure is based on a Huffman code with a number of points on each layer and number of layers, represented as Ni and S, where i in Ni denotes a sequence of N values, further comprising:
• searching over all possible Ri as a radius of each layer, with a defined step size Δr and where i in Ri denotes a sequence of R values;
• searching over a relative angle for each layer with another step size Δθ;
• after increasing each step size, determining a constellation figure of merit (CFM) and searching over a given range of radius and angle and determining a combination with maximum CFM;
• and
• with the radius of each layer and the relatively angle for each layer specified, determining constellation sets with Ni and S.