Iterative Channel Estimation and Data Detection of OTSM With Superimposed Pilot Scheme and PAPR Analysis

Orthogonal time sequency multiplexing (OTSM), a novel modulation scheme proposed recently performs superior to orthogonal frequency division multiplexing (OFDM) under doubly dispersive channel. In this Letter, we propose iterative channel estimation and data detection for OTSM systems with superimposed pilot scheme. The channel estimation is done initially considering pilot-data interference (PDI) as noise with high power pilot signal. From the second iteration onwards, PDI is eliminated based on the estimated channel and detected symbols. Block by block symbol detection in the time domain is performed by eliminating another interference known as inter block interference (IBI) between the blocks. The peak to average power ratio (PAPR) is evaluated for OTSM and it is found to increase linearly with the number of sequency bins and not delay bins. The PAPR is reduced with this superimposed pilot scheme compared to conventional zero padded (ZP) pilot scheme. The evaluated error performance of superimposed pilot scheme is close to ZP OTSM scheme with less pilot power.