OTFS-IM with Decode and Forward Relaying

Orthogonal time frequency space (OTFS) modulation and index modulation (IM) are promising techniques in wireless communications. OTFS excels in high mobility scenarios by using information signaling in the delay-Doppler domain, while IM offers improved spectral efficiencies and bit error performance. In this study, we analyze the performance of OTFS with IM (OTFS-IM) in a decode-and-forward (DaF) relay communication system. The communication involves two hops between the transmitter, receiver nodes through a relay node. We derive a closed-form expression for the end-to-end pairwise error probability in OTFS-IM with DaF relaying and assess the achieved asymptotic diversity order. Our simulation results show that i) the use of indexing improves the performance of OTFS with DaF relaying ii) the simulated upper bound on the bit error rate (BER) validates the analytically predicted diversity orders.