An Efficient Node Design for underwater acoustic communication based on OFDM

Acoustics is the most efficient carrier for long-range information transmission under the water. Recently, the Orthogonal frequency-division multiplexing (OFDM) is used for high-speed underwater acoustic communication because of its high efficiency in using wideband frequency and strong resistance to inter symbol interference (ISI). However, this modulation requires large-scale computation so each node consumes huge amount of power. When the power is insufficiency, the node may collapse. In order to solve this problem, optimized transmission and receiving algorithm are developed on an ARM9-based embedded system, which equipped with an additional DSP (TI C6748). The ping-pong processing and data transmission are realized by using a DMA address list, while the modulation is optimized by using the TI's DSP function library. The optimized transmission and receiving algorithm are implemented in underwater acoustic communication. Different pilots are applied to test the system performance. Low BER is achieved and power consumption is reduced.