an encoding method for encoding information bits into a codeword by a linear code is provided . the information bits appear in the codeword as a part of the codeword . the linear code is a code in which a codeword resulting from cyclically shifting an arbitrary codeword by p bit positions is also a codeword . a code polynomial having the codeword in which the information bits appear as a part thereof is computed by executing an arithmetic operation of p polynomials g 0 , . . . , g p − 1 and a polynomial having the information bits as coefficients . accordingly , a quasi - cyclic code can be encoded by only polynomial operations , and an encoder can be simplified .