Greedy Sparse Channel Estimation Framework for Multi-User OTFS Systems

In this work, we address the problem of estimating the channel state information for the uplink multi-user orthogonal time frequency space (OTFS) systems without having prior knowledge of delay-Doppler locations. Here, we consider conventional pilot-based OTFS transmit frame structure with rectangular pulse shaping technique for the muti-user OTFS systems and use the recently proposed greedy algorithm known as two choice hard thresholding pursuit (TCHTP) to estimate delay-Doppler channel. Through numerical simulations, we compare the performance of the proposed TCHTP based channel estimation framework with the existing orthogonal matching pursuit based channel estimation technique in terms of the mean squared error, the bit-error rate and computational complexity.