A method for encoding a bitstream is described. The method includes receiving, by an error correction unit, the bitstream; performing, by the error correction unit, encoding on the bitstream to generate an encoded bit stream that includes the bitstream and parity bits; processing, by a constellation unit, the encoded bitstream to generate constellation points in one or more encoded streams; determining, by a low-density parity-check (LDPC) tone mapper, a distance between subcarriers in an Orthogonal Frequency Division Multiplexing (OFDM) symbol of the frame; and performing, by the LDPC tone mapper, LDPC tone mapping based on the one or more encoded streams and on the determined distance to generate a permuted stream of complex numbers, wherein the distance between subcarriers is determined to be either (1) 18 for a first resource unit size used in the frame and (2) 20 for a second resource unit size used in the frame.