Performance of block adaptive modulation schemes for OFDM based WLAN systems

We have investigated different block adaptive modulation (BAM) techniques for OFDM-based wireless LAN systems. Two new algorithms for bit allocation of a block of subcarriers are proposed and the performance of these schemes is compared with an existing scheme. The IEEE 802.11a physical layer is simulated and performance results are presented under various conditions. Results indicate the advantages of the new algorithms under specific conditions. The effects of channel estimation errors on performance are also studied. We also present a technique to improve the performance of BAM schemes.