Impact of front-end non-idealities on bit error rate performance of WLAN-OFDM transceivers

New OFDM-based WLAN standards target wireless communications in the 5 GHz band for consumer multimedia applications. Given the high data rates with required low bit error rates, and given the nature of the OFDM signal, a conservative analysis of the front-end requirements lead to severe, over dimensioned specifications. Such a design would never meet this market, by necessity low-cost and low-power. To extract more optimal front-end specifications, we assess the BER performance of the complete WLAN-OFDM link. As a result, we first show that the transmitted symbols' word-length can be restricted to 8-bit and the normalized crest factor digitally limited at baseband to 4. Then we show that the power amplifier can operate with only 5.4 dB back-off between the average input power and the input-referred P/sub ldB/. Finally, we quantify in terms of implementation loss the influence of the I/Q imbalance and of the frequency synthesizer phase noise.