On pilot-symbol aided channel estimation in FBMC-OQAM

Filter bank multicarrier modulation is considered as a possible candidate for 5G. In this paper, we consider pilot-symbol aided channel estimation and address the problem of canceling the imaginary interference at the pilot positions. We develop a matrix formulation for the transmission system which allows us to formulate general conditions on the auxiliary pilot symbols, capturing also the interde-pendency of closely spaced pilots and an arbitrary number of auxiliary pilot symbols. By using two auxiliary symbols per pilot instead of one, we are able to improve the peak-to-average power ratio as well as the achievable capacity for small to medium signal-to-noise ratios. The achievable capacity can further be increased by interference cancellation based on linear precoding for which we propose an algorithm to find the coding matrix required. Finally, we compare auxiliary pilot symbols and linear precoding in terms of complexity and performance.