Comparison of SC-FDM with OFDM in underwater acoustic communication system

This paper compares Single Carrier Frequency Division Multiplex (SC-FDM) with Orthogonal Frequency Division Multiplex (OFDM) for underwater acoustic communication. One of the drawbacks of OFDM transmission is the large variations in the instantaneous transmit power. This implies a reduced efficiency in power amplifiers and results in lower average power of the transmission signal. SC-FDM is utilized for 4G radio access technology such as Uplink communication of Long Term Evolution (LTE) in order to mitigate the above drawback of OFDM. Among the modulations in this communication system are QPSK, 16QAM and 64QAM. Zadoff-Chu sequence is used as Pilots for SC-FDM both for Channel Estimation and Phase Compensation of Doppler shift. Both Field Experiment at sea port in Okinawa, Japan and computer simulation show the quantitative merits of SC-FDM than OFDM. Peak-to-average Power Ratio (PAPR) of the transmitted signal has been successfully reduced by 1.5–2.0 dB for various modulations and roughly 50% of communication distance can be extended.