A Novel Blind Delay Spread Estimation using Frequency Correlation for Wireless OFDM Systems

In this paper we propose a novel blind Delay Spread (DS) estimator for wireless Orthogonal Frequency Division Multiplexed (OFDM) systems. DS gives a measure of the frequency selectivity of the wireless channel, which can be used for channel estimation and to adjust the guard interval size to avoid Inter-Symbol Interference. The estimator is based on the frequency correlation between subcarriers of one OFDM symbol and an expression between frequency correlation and DS is derived assuming an exponentially decaying power delay profile (PDP). To derive the frequency correlation values we use frequency separation values different to zero, which to the best of authors´ knowledge is the first time that is introduced. The estimation accuracy, examined in environments with different PDPs, including transceiver mobility and channel sparsity, using several constellation schemes is very high from low SNR values with small variance.