HF Skywave Massive MIMO Communications with Interference Sparsity-Aware Turbo Receiver

In this paper, we propose a low complexity turbo receiver for high frequency (HF) skywave massive multiple-input multiple-output (MIMO) systems. By leveraging the beam based channel model (BBCM), we reveal the interference sparsity of HF skywave massive MIMO systems. Exploiting the interference sparsity, we provide a condition of extracting sufficient observation for signal detection. Motivated by this condition, we construct the interference user terminal (UT) set (IUS) and extract the observation vector from the received signal after matched filtering (MF) for each UT. Then, a low-dimensional interference sparsity-aware detector (ISD) is separately designed for each UT, and the interference sparsity-aware turbo receiver (ISTR) is subsequently formulated using ISDs. Further, we develop an efficient implementation of the ISTR, involving approximate computations of the ISD and the signal reconstructed by ISD. Simulation results confirm that the proposed ISTR achieves excellent performance with relatively low complexity.