Frequency Domain Channel Estimation for Single-Carrier Uplink in Time-Varying Channels

We compare the performance of channel estimators for single-carrier (SC) systems using frequency domain multiplexed (FDM) and time domain multiplexed (TDM) pilot schemes, in terms of total overhead (including pilots, cyclic prefix and unused subcarriers), the required power backoff for the power amplifier and the frame error rate (FER) in time-varying channels. Channel estimators using FFT in the frequency direction and least square line fitting in the time direction, and Wiener filtering in both time and frequency directions are considered. We also proposed a low computational complexity hybrid estimator using FFT in the frequency direction and Wiener filtering in the time direction when on-line calculation of Wiener filter taps is required. We found that SC with TDM pilots gives the least power penalty due to the combination of SNR degradation at FER = 10 and required transmitter power backoff for a given power amplifier. SC with FDM pilots and orthogonal frequency division multiplexing (OFDM) schemes are about 1 to 2 dB worse than that of TDM pilots.