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Novel Pilot Position Selection and Signal Reconstruction Methods for Frequency-Domain Pilot Multiplexing Techniques of SC-FDE

The frequency-domain pilot multiplexing technique (FDPMT) has recently emerged as an appealing technique for channel estimation in single-carrier frequency-domain equalization (SC-FDE) systems due to the high spectral efficiency it promises. However, the performance of the FDPMT system is significantly affected by the signal distortion level, which depends on the pilot position selection (PPS) strategy at the transmitter and the signal reconstruction (SR) ability of the receiver. In this paper, the relationship between the interference pattern and the loss of equally spaced tones is discovered. By exploiting this relationship, we propose a novel PPS method and a novel SR method. The proposed PPS method, which is based on the minimization of the most severe intersymbol interference (ISI) experienced by those subblocks decimated from the transmitted signal block, dispenses with a priori knowledge of the channel statistics and imposes very low computational cost to the transmitter. The proposed SR method, which is based on the maximum-likelihood criterion, can be carried out subblock by subblock in parallel and sample by sample within each subblock, saving the computational complexity and time consumption of the receiver. Simulation results in terms of bit error rate (BER) corroborate the superiority of both proposed methods over their existing counterparts in various channels of interest.