— A low complexity frequency domain iterative decision-directed channel estimation (FD-IDDCE) technique for single-carrier (SC) systems with frequency domain multiplexed (FDM) pilots is proposed. The tentative hard decisions from either the frequency domain equalizer output or the Viterbi decoder output are used as extra pilots to further improve the initial frequency channel estimates using a cascaded 2 × 1D Wiener filter. The issue of noise enhancement when finding the least square (LS) estimates of the channel frequency response (CFR) using the tentative decisions in the frequency domain is overcome by the so called frequency replacement algorithm, which replaces the noise enhanced LS estimates of the CFR with the corresponding channel frequency estimates in the previous iteration, by comparing with a threshold. Using the proposed FDIDDCE, the frame error rate (FER) performance for coded SC systems using FDM pilots with frequency expanding technique and frequency domain superim...
Chan-Tong Lam, David D. Falconer, Florence Danilo-