Abstract: A simulink PHY layer platform of OFDM-based IEEE 802.11a was built. The modified puncturing method and a new construction of the matrix interleaving method were proposed to improve the function of the codec module. The former is based on the principle of Viterbi decoding and the latter is based on improving the convolution coder with relevant theories. Simulations were done under different E_b/N₀ by controlling the parameters of the IEEE 802.11a PHY layer platform. Conclusion reveals that, compared with the BER performance using given puncturing method in IEEE 802.11a, the BER performance of the OFDM system could increase about 3 dB by using proposed puncturing method. Also, the new matrix interleaving construction could provide the increase of BER performance about 1 to 2 dB when the E_b/N₀ is greater than 5 dB.