Pilot design for non-contiguous spectrum usage in OFDM-based cognitive radio networks

In this paper, challenges regarding the provision of channel state information (CSI) in non-contiguous orthogonal frequency division multiplexing (NC-OFDM) cognitive radio (CR) systems are addressed. We propose a novel scheme that utilizes convex optimization together with the cross entropy (CE) optimization to design pilot symbols that minimizes the channel estimate mean squared error (MSE) of frequency selective channels. Simulation results indicate that, the proposed pilot symbol design provides better channel estimate MSE as well as the bit error rate (BER) performance when compared with the equal powered pilot design.