OTFS Modulation and PAPR Reduction for loT-Railways

The internet of things(IoT)has been widely considered to be integrated with high-speed railways to improve safety and service.It is im-portant to achieve reliable communication in IoT for railways(IoT-R)under high mobility scenarios and strict energy constraints.Orthogonal time frequency space(OTFS)modulation is a two-dimensional mod-ulation technique that has the potential to overcome the challenges in high Doppler environments.In addi-tion,OTFS can have lower peak-to-average power ra-tio(PAPR)compared to orthogonal frequency division multiplexing,which is especially important for the ap-plication of IoT-R.Therefore,OTFS modulation for IoT-R is investigated in this paper.In order to decrease PAPR of OTFS and promote the application of OTFS modulation in IoT-R,the peak windowing technique is used in this paper.This technique can reduce the PAPR of OTFS by reducing the peak power and does not require multiple iterations.The impacts of differ-ent window functions,window sizes and clipping lev-els on PAPR and bit error rate of OTFS are simulated and discussed.The simulation results show that the peak windowing technique can efficiently reduce the PAPR of OTFS for IoT-R.