Performance Analysis of MIMO-OTFS with Selective Decode and Forward Relaying

In this paper, we analyze the performance of multiple-input multiple-output orthogonal time frequency space (MIMO-OTFS) modulation with selective decode-and-forward (SDaF) relaying. Communication between the sender and destination nodes happens in two hops using multiple relays out of which some selected relays aid the communication. All the nodes are provided with multiple transmit and multiple receive antennas. We derive closed-form expressions for the end-to-end pairwise error probability and bit error probability upper bounds in MIMO-OTFS with SDaF relaying, and characterize the achieved asymptotic diversity orders. We also investigate the considered system when phase rotation of OTFS frames is performed to improve the diversity performance. Simulation results are shown to validate the analytically predicted diversity results.