Determine optimal bandwidth for modulation in underwater communication channel based on PSO

Underwater acoustic communication is paid more and more attention with the development of marine researches in recent years. Underwater acoustic communication channel is considered to be one of the most complicated channels, it suffers from the less available bandwidth, the more serious multipath effect and the even complex noise. Due to the severe distortion of the received signals, the underwater acoustic communication always experiences a high Bit Error Rate (BER). To solve this problem, Carrier Waveform Inter-Displacement (CWID) modulation was proved to be an effective method to decrease BER in our previous work. The Linear Frequency Modulation (LFM) carrier-waves are used in CWID modulation. The frequency band of LFM carrier-waves has an important effect on the communication performance. The Particle Swarm Optimization (PSO) is introduced to search the optimal frequency band of the LFM carrier-waves in this paper, due to its excellent performance in solving complicated optimization problems. The multiple objective optimization nature of the PSO gives a clear hint to deduce the relationship of upper band and lower band of the LFM carrier-waves. Simulations verify the improved performance and effectiveness of the optimization method.