The application relates to an apparatus and method used in Wireless Local Area Networks (WLANs). The apparatus includes: a wireless interface; and processor circuitry coupled to the wireless interface and configured to: generate a Physical layer Protocol Data Unit (PPDU) with a Low Density Parity Check (LDPC) coding scheme; and provide the PPDU to the wireless interface for transmitting, wherein the PPDU comprises one special codeword and more than one regular codeword and does not comprise a padding bit before Forward Error Correction (FEC) codes, and the regular codeword has a fixed codeword size, which can be different from a codeword size of the special codeword.