Performance analysis of adaptive equalizer design for CCK-OFDM wireless LAN

An adaptive equalizer scheme is presented in the CCK-OFDM system for an IEEE 802.11g wireless LAN. The conventional OFDM system employs a guard interval and 1-tap frequency-domain equalizer (FEQ) to prevent delay spread distortion. When the channel impulse response (CIR) is larger than the guard intervals, the system performance is restricted by ISI and ICI. The proposed equalizer scheme consists of an adaptive time-domain equalizer (TEQ) using single carrier training data and a 1-tap FEQ using long training OFDM symbols. Its performance is better than the conventional OFDM system under severe delay spread and noise power conditions, especially in the case of CIR larger than guard intervals. This enables a reduction in the size of the guard interval, and thus the transmission efficiency of the OFDM system can be improved.