Non-Coherent MIMO Scheme Based on OFDM-MFSK

We propose a non-coherent transmission system based on orthogonal frequency division multiplexing (OFDM) for low-power applications. The proposed system uses M-ary frequency shift keying (MFSK) and employs two transmitting and two receiving antennas, with encoding across the space, frequency and time domains. For the resulting scheme, we develop a novel optimal non-coherent detector that produces soft bit information for a state-of-the-art error correction decoder. The proposed solution eliminates the need for channel knowledge and enables a simple receiver structure. Simulation results demonstrate an up to 8 dB coding gain of the proposed scheme over single-antenna OFDM-MFSK. When compared with coherent systems based on OFDM and binary phase shift keying (BPSK), the designed scheme offers a receiver sensitivity gain of 9 dB and beyond.