Performance of the Pre/Post-FFT Smart Antenna Methods for OFDM-Based Wireless LANs in an Indoor Channel with Interference

The performance of OFDM-based Wireless Local Area Networks (WLANs) is investigated by employing different smart antenna techniques at the receiver. The use of multiple antennas at the Access Point (AP) receiver in IEEE802.11a standard-compliant Single Input Multiple Output (SIMO) configuration, improves the physical layer performance in different channel scenarios and interference that may arise from other stations sharing the same frequency band. For this purpose, a comparative study of smart antenna architectures for IEEE802.11a WLAN system using pre-FFT and post-FFT array processing techniques is presented. Simulations are performed on a new model for IEEE802.11a system using a spatio-temporal channel model which is developed based on a measured wideband channels in the 5GHz band. Bit-Error-Rate (BER) performance for QPSK modulation at LOS, OLOS and NLOS channel scenario along with co-channel interference is evaluated. Simulation results demonstrate the effectiveness of employing the proposed pre-FFT signal processing.