  Due to the ever increasing data rate demand of beyond 5G networks and
considering the wide range of Orthogonal Frequency Division Multipllexing
(OFDM) technique in cellular systems, it is critical to reduce pilot overhead
of OFDM systems in order to increase data rate of such systems. Due to sparsity
of multipath channels, sparse recovery methods can be exploited to reduce pilot
overhead. OFDM pilots are utilized as random samples for channel impulse
response estimation. We propose a three-step sparsity recovery algorithm which
is based on sparsity domain smoothing. Time domain residue computation,
sparsity domain smoothing, and adaptive thresholding sparsifying are the
three-steps of the proposed scheme. To the best of our knowledge, the proposed
sparsity domain smoothing based thresholding recovery method known as SDS-IMAT
has not been used for OFDM sparse channel estimation in the literature. Pilot
locations are also derived based on the minimization of the measurement matrix
coherence. Numerical results verify that the performance of the proposed scheme
outperforms other existing thresholding and greedy recovery methods and has a
near-optimal performance. The effectiveness of the proposed scheme is shown in
terms of mean square error and bit error rate.
