IMPACT OF QUANTIZATION ON CHANNEL ESTIMATION IN OFDM COMMUNICATION SYSTEM
Orthogonal frequency division multiplexing (OFDM) system with frequency domain equalization (FDE) requires reliable channel estimation (CE). In practice, pilot assisted CE can be either based on timeor frequency-domain multiplexed pilot symbols (i.e. TDM-pilot and FDM-pilot). It this paper, the impact of quantization noise introduced by digital-to-analog (DA) and analog-to-digital (AD) converters is examined. Furthermore, the trade-off between the resolution of DA/AD converters and back-off levels of the DA converter is evaluated. The simulation results are provided in terms of bit error rate (BER) for different configurations of the OFDM system. We show, that TDM-pilot CE scheme requires lower DA and AD converter resolutions than FDM-pilot CE scheme to achieve comparable performance. This is a consequence of pilot symbols’ amplitude clipping at the DA converter and/or large amplitudes that need to be covered by AD converter in the case of FDM-pilot CE scheme. This is not the case in TDM-pilot CE scheme, where Chu pilot sequence with constant amplitude of pilot symbols is applied.