Novel signal reconstruction method for SC-FDE systems with frequency domain pilot multiplexing technique over time-varying channels

The frequency domain pilot multiplexing technique (FDPMT) for channel estimation prevails in single-carrier frequency domain equalization (SC-FDE) systems for high spectral efficiency it promises. However, the bit error rate (BER) performance of the system with FDPMT can be significantly affected by the signal distortion level, which depends on the signal reconstruction (SR) ability of the receiver. In this paper, we are the first to discover that the time domain distortion block due to the removal of several equal-spaced data tones is comprised of an equal number of independent distortion sub-blocks. Motivated by this property, we therefore propose a novel SR method based on the maximum-likelihood (ML) criterion. It can be carried out sub-block-by-sub-block in parallel and sample-by-sample within each sub-block, keeping similar computational complexity to the existing SR method. More importantly, it gets rid of the error propagation problem that is encountered in the existing SR method, thus exhibiting much better BER performance over time-varying Rayleigh fading channels.

I. Introduction

SC-FDE is a promising technique for the uplink communication since it keeps lower peak-to-average power ratio than orthogonal frequency division multiplexing (OFDM) [1]–[3]. In SC-FDE, the pilots used for channel estimation can be inserted in either frequency domain or time domain. Compared with the time domain multiplexed (TDM) pilot insertion technique, the frequency domain multiplexed (FDM) one is more effective in tracking the doubly-selective fading channel [1], [4], [5]. There are three FDM pilot insertion techniques available in the literature, including the frequency expanding technique (FET), the frequency domain superimposed pilot technique (FDSPT), and the FDPMT [5]–[7]. Compared with the other two techniques, the FDMPT attracts much more attention owing to its capability of recovering the loss of spectral efficiency which happens in the FET and avoiding the degradation of BER performance which happens in the FDSPT [5].