An apparatus and method for generating a (n, 3) code and a (n, 4) code using simplex codes are disclosed. To encode a 3-bit information bit stream to a (n, 3) codeword with n code symbols, a simplex encoder generates a first-order Reed-Muller codeword with (P+1) code symbols from the input information bit stream for n>P, and punctures the first code symbol of the (P+1) first-order Reed-Muller code symbols to produce a (P, 3) simplex codeword. An interleaver permutates the P code symbols of the (P, 3) simplex codeword by columns according to a predetermined pattern. A repeater repeats the column-permutated (P, 3) simplex codeword until the number of repeated codes is n and outputs a (n, 3) codeword with the n repeated code symbols.