A communication device is configured to encode information bits using one or more forward error correction (FEC) codes and/or error correction codes (ECCs) to generate different codewords (e.g., codeword groups having different lengths, based on different code rates, etc.). The device generates a combined codeword using different sized codewords (e.g., long, medium, and short) by filling fills long codewords completely if possible, then filling medium codewords completely if possible with the remaining message bits (if any), and filling short codewords completely if possible plus another additional short codeword with the remaining message bits (if any). If the total number of short (or medium and short) codeword parity bits is greater than or equal to the number of medium (or long) codeword parity bits, then the device increments the number of medium (or long) codewords by one and setting the number of short (or medium and short) codewords to zero.