A method and apparatus for channel encoding and channel decoding in a wireless communication system are provided. The channel encoding method includes generating a first parity set and a second parity set based on information bits, determining a number of additional parity bits based on a number of the information bits and a required coding rate, generating the determined number of additional parity bits using the information bits, and generating a codeword including the information bits, the first parity set, the second parity set, and the generated additional parity bits.

There is provided an encoding circuit used for coherent digital signal processing, including: a serial-parallel circuit that divides input data into a plurality of pieces of divided data by serial-parallel conversion; a plurality of encoders that adds an error correction code to the divided data and encodes the divided data; and a bit conversion circuit that converts a bit sequence in order to make an amount of noise generated by a communication channel non-uniform among the plurality of pieces of divided data encoded by each of the plurality of encoders.