Design for IEEE 802.11a based WLAN OFDM modem

Abstract

Orthogonal frequency division multiplexing (OFDM) is one of the most promising techniques for future high data rate wireless communication systems. Several algorithms for wireless multimedia systems were proposed and adopted as standards. We design IEEE 802.11a based OFDM system with hardware description language and verify it``s performance. We evaluate the algorithms for the IEEE 802.11a OFDM system by floating point simulation. Based on these simulation results, we make hardware design and verify with the results of hardware implementation. In this thesis, we focus on the synchronization and channel estimation and compensation. Also, we mainly deal with functional level simulation for the hardware design and consider some limitations such as complexity. IEEE 802.11a based OFDM system does not support the mobility and thus it can not combat the channel effect at high mobile environment. In this thesis, we propose a new channel tracking algorithm which is based on the modification of pilot pattern and linear interpolation without generating the reference data from received data. For the purpose of accurate channel tracking, the variation of the channel is examined by correlation analysis. In here, we use the linear interpolation for channel tracking. Without loss of data rate, the method reduces the error floor of bit error rate (BER) dramatically. Simulation results demonstrate the capability of channel tracking when the Doppler shift is very large.