Fading Effects on the Performance of OFDM-Based Systems Using Channel Transfer Function

The channel transfer functions (or channel gains) of fading channels significantly impact both the received SNR (signal-to-noise ratio) and the PER (packet error rate) of received packets in OFDM-based WLANs. This paper uses the probability distribution of the average channel gain of the fading channel to analyze the degree of fading effects on the PER in OFDM systems. PER performance of the received SNR is obtained for different rate modes both by an analytical approach and by the simulation. PER performance comparisons between ETSI/BRAN A and C channel models are investigated in 802.11a/g WLANs. Numerical results show that the performance of BRAN A channel outperforms BRAN C channel for all rate modes when the initial SNR is very low, for instance target Eb/No = 6 dB. When the initial SNR value is medium (e.g. Eb/No = 12 dB) or high (e.g. Eb/No > 18 dB), BRAN C channel has a better performance than BRAN A channel for low rate modes 12 Mb/s and 24 Mb/s due to that BRAN A channel has much higher probability than BRAN C channel to have smaller values of average channel gain. For high rate modes 36 Mb/s, 48 Mb/s and 54 Mb/s, BRAN A channel outperforms BRAN C channel due to that BRAN A channel has higher probability to have larger values of average channel gain than BRAN C channel.