Acoustic Communications Modem Using MIMO Technology

The proposed Phase II STTR project is a joint effort between Heat, Light and Sound Research Inc (HLS Research), Arizona State University (ASU), and BAE Systems, titled Acoustic Communications Modem Using Multiple Input, Multiple Output (MIMO) Technology. The Phase I contract (N00014-05-M-0224) was awarded HLS Research and ASU under STTR Topic N05-T022, titled Underwater Acoustic Communications. The Phase I effort has demonstrated the feasibility of using MIMO technology for shallow water (horizontal) acoustic communications at ranges of several kilometers. The objectives achieved using MIMO communications include: 1) dramatically increased data rates with reliable decoding performance (48 kbps using 4 transmitters with BER less than 1%, 32 kbps using 4 transmitters with BER of 0%, both in a 25 kHz band at 2 km range using packet sizes of 19200), and 2) dramatically increased spectral efficiencies (4 bits/sec/Hz using 6 transmitters with BER of 1.3% at 2 km range in 3 kHz band using packet sizes of 57600). These results were demonstrated by processing realistic shallow water data collected during the ONR-funded at-sea Makai experiment off the coast of Kauai. For our Phase II effort, we are proposing to further develop the basic algorithms, to demonstrate higher rates on already recorded at-sea data (using more transmitters and higher order constellations), and a number of enhancements that will lead to fully autonomous operation, including adaptive modulation and improvements to enable operation in Doppler conditions.