A 31.8kbps/8kHz Underwater Acoustic Single Carrier Frequency Division Multiplexing (SC-FDM) Communication System with Forward Error Correction

摘要

This paper proposes an underwater acoustic Single Carrier Frequency Division Multiplexing (SC-FDM) communication system with a forward error correction to transmit image or movie data packet from deep sea ROV (Remotely operated vehicle) etc. to surface ship. Since the SCFDM is basically Orthogonal Frequency Division Multiple Access (OFDM) with pre- and post-coding, frequency bandwidth is efficiently utilized to deliver high data bandwidth as well as lower Peak-to-Average-Power Ratio (PAPR) of the transmitting signal. In order to realize error-free communication adaptively to wide range of Carrier signal to Noise power Ratio CNRs, 3 carrier modulations such as QPSK/16QAM/64QAM and 5 code rates are supported. Using 64QAM with code rate R=7/8, a 31.8 kbps in 8kHz maximum channel bandwidth has been achieved. The system utilized 20-28 kHz and subcarrier spacing of 50 Hz. Total number of sub-carriers is 161. The system is verified by Ocean experiment at Suruga Bay with 1000m deep sea in Shizuoka, Japan. At the depth of 100m, with 64QAM and code rate R= 3/4 (Rate=27.241 kb/s), Packet Error Rate (PER) =0 % is observed. At the depth of 400m, with 64QAM and R=2/3 (Rate=24.213 kb/s), PER=0 % is also achieved. At the depth of both 700 and 1000m, with 16QAM and code rate R= 2/3 (Rate=16.140 kb/s), PER closed to 0 % is realized.