Turbo coded OFDM for wireless local area networks

A new block turbo coded-OFDM (BTC-OFDM) system is proposed for wireless local area network (WLAN) applications to provide better performance and more efficiency compared to the IEEE802.11a standard. The proposed scheme uses the same parameters for OFDM as given in IEEE802.11a. This BTC-OFDM utilizes the diversity in both the time and frequency domains to achieve higher performance and more robustness against frequency and time selective fading. The system performance is evaluated by simulation over an AWGN channel, a Rayleigh fading channel and a multipath channel model. The benefits of using OFDM and turbo codes are studied separately. It is shown that turbo codes can greatly improve the system performance and overcome residual intersymbol interference (ISI) and intercarrier interference (ICI) and allow the use of a shorter cyclic prefix in an OFDM system. In conclusion, the use of turbo codes in an OFDM system for a high data rate transmission in wireless LANs, results in a considerable improvement in terms of the bit error rate performance and bandwidth efficiency.