A Multiple Sequences Spread-Spectrum System with In-phase/Quadrature Index Modulation for Underwater Acoustic Communications

In the multiple sequences spread system (MSSS), multiple modulated spreading sequences by a groups of symbols are superimposed at the transmitter. In this paper, we propose a new multiple sequences spread-spectrum system with in-phase/quadrature index modulation (MSSS-I/Q-IM), which can achieve higher spectrum efficiency by using code index modulation to carry two groups of additional bits. In the...