Comparative bit error rate and capacity analysis for adaptive OFDM-based indoor WLAN system

Here I have developed a primary variable bit, variable power loading algorithm based on some previously published algorithms and extended the same to incorporate a sub-band loading scheme to further reduce complexity, and introduced a switching scheme to achieve more reliable high-speed transmission. This scheme can achieve a constant target BER, along with a variable bit rate or a constant target bit rate, as high as allowed by the channel. I have developed several non-adaptive or partially adaptive loading schemes and a comparative performance analysis in terms of BER and capacity has been carried out by simulation to quantify the performance gain of the fully adaptive variable bit-power with sub-band loading over these non-adaptive cases. The results indicate that the standard non-adaptive OFDM as in IEEE802.11a has severe limitations in BER performances for high-speed applications and sub-band adaptive loading achieves a SNR gain of more than 15 dB for equivalent BER of 10−3 and more than 20 dB for a BER of 10−4 over fully non-adaptive case, along with a capacity gain of more than 35%. It is shown that for the adaptive algorithm with coding and interleaving, BER performance improves greatly for lower bit rates, but with a reduction in capacity. (Abstract shortened by UMI.)...