Pilot Placement Algorithms for OFDM Based Communications in Indoor Wideband Channels

This work considers the placement of pilot symbols in orthogonal frequency division multiplexed transmissions, to minimise the mean squared error in the corresponding channel estimation. We show that further improvements in this widely investigated topic are possible, for example, in indoor wideband channels, which are subject to significantly correlated scattering processes. Noting that the naive approach incurs a prohibitive complexity, low complexity greedy solutions are developed. A measurement campaign is conducted to estimate real-world channel statistics in an indoor wideband environment. It is confirmed that practical channels are correlated, even to the extent of exhibiting rank deficiencies, and that the proposed placement algorithms result in improved channel estimation performance.