LAUSR

Underwater acoustic (UWA) channels exhibit double selectivity in both time and frequency domains, posing significant challenges to reliable UWA communications. This correspondence paper presents a novel spatial block coding scheme integrated with complementary code keying (CCK) modulation to exploit both spatial diversity and code diversity against doubly selective fading channels. The proposed spatial-CCK modulation utilizes multiple transmit transducers and extends the traditional CCK code set to improve receiver performance. We introduce novel code design criteria by considering maximum likelihood detection receivers under fast Rayleigh fading channel condition. Simulation and lake experiment results demonstrate substantial performance gain by the proposed spatial-CCK scheme over the conventional space–time codes without incurring additional high complexity cost for UWA channels.