A scheme combining layered space-time coding with spectrum spreading for underwater acoustic communication system

Underwater acoustic (UWA) communication researches continue to focusing on higher spectrum-efficiency. This paper proposes a low complexity spatial parallel transmitting scheme based on layered space-time coding and spectrum spreading, named LST-SS scheme, to increase spectrum efficiency of UWA communication systems. In this scheme, layered signals are spread by the spreading code. Detection of signals from different layers is implemented based the channel delays and Rake receivers with only one receiving hydrophone. The autocorrelation and cross correlation properties of spread-spectrum sequence are used to achieve the signal separation and interference suppression. Simulation and the lake trial results show that the LST-SS scheme has better error performance compared with single transmitting transducer scheme when the systems have the same data rate.