Performance Analysis of MIMO-OTFS with Decode and Forward Relaying

In this paper, we analyze the performance of multiple-input multiple-output orthogonal time frequency space (MIMO-OTFS) modulation with decode and forward (DaF) relaying. Communication between the transmitter and receiver nodes happens through a relay node in two hops. All the nodes are provided with multiple transmit and multiple receive antennas. We derive a closed-form expression for the end-to-end pairwise error probability in MIMO-OTFS with DaF relaying and characterize the achieved asymptotic diversity order. 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 performance.