Relay-assisted space-time block code (STBC) and space-frequency block code (SFBC) for single carrier frequency-domain equalization (SC-FDE) were presented. They achieve spatial diversity over fading relay channels under the assumption of perfect channel state information (CSI). In this paper, we propose a pilot position selection/detection technique for channel estimation of those systems. Unlike the conventional block-type channel estimation techniques, the proposed scheme superimposes pilots on data-carrying tones whose positions are selected to minimize the distortion of original signals. Without additional pilot overhead, the proposed technique can track the CSI even when the mobile equipment speed is high. The corresponding destination structure and frequency domain equalization are also presented, where the pilot positions are blindly detected and the distorted data symbols are iteratively reconstructed. Simulation results show that the proposed method gives better BER performance than the block-type channel estimation for the distributed SFBC (D-SFBC) SC-FDE over fast fading relay channels, without the loss of spectral efficiency.
['Dongsik Kim', 'Ui-Kun Kwon', 'Gi-Hong Im', 'Changyong Shin']
A Pilot Design Technique for Single-Carrier Transmission over Fast Fading Relay Channels