Frequency-Domain Equalization for Single Carrier MIMO Underwater Acoustic Communications

This paper describes a frequency-domain equalization (FDE) method for single carrier (SC) multiple input multiple output (MIMO) underwater acoustic communications with multiple transducer transmitters and multiple hydrophone receivers. The proposed MIMO SC-FDE method is applied to fixed-to-fixed undersea data collected during the RACE08 ocean experiments in March 2008, where single carrier transmission was employed with phase shift keying (PSK) modulations. The time-varying multipath channels are estimated in the time domain by training symbols at the front of each data block. The average uncoded bit error rate for two-transducer twelve-hydrophone with QPSK modulation is 1.8% for a 1000 meter range system and 1.2% for a 400 meter range system, when the data block length is 1024, which includes 150 training symbols, the channel bandwidth is 3.90625 kHz and the carrier frequency is 11.5 kHz.