Low Complexity Joint OMP Methods for FDD Channel Estimation in Massive MIMO Systems

The downlink channel estimation techniques in FDD (frequency-division-duplex) massive MIMO (multiple-input multiple-output) systems rely upon the spatial reciprocity to obtain the spatial information of the multi-path channel. In this paper, we investigate the low-complexity algorithm based on the Newtonized orthogonal matching pursuit (NOMP) algorithm. Towards that, we first derive an NOMP approach for joint parameters updates. Further, to reduce the computational overhead of the updates, we relax the Hessian to be block diagonal. Simulations demonstrate that the both algorithms achieve an approximately similar performance as compared to the recent approach in [1], while incurring lower overheads.