Design and implementation of bidirectional OFDM modem prototype for high-speed underwater acoustic communication systems

Recently, underwater acoustic communication system has been received a great interest due to its wide application areas. Since acoustic modem is one of the core technologies for underwater communication systems, there have been many efforts to improve the performance of acoustic modem in terms of data rate, working range, power consumption, size and cost by utilizing state-of-the-art physical layer techniques. In this paper, we design and implement a prototype of a micro modem based on orthogonal frequency division multiplexing (OFDM), which is equipped with a digital module, an analog module, and an omnidirectional transducer. Also, we build a frame structure for the micro modem to perform an efficient communication in underwater. Indoor and outdoor experiments are conducted in a water tank and a pond and performances are investigated. Since the micro modem provides high-speed and reliable communication in underwater, it could be applied for various aquatic applications including underwater wireless sensor networks and underwater mobile systems.