Experimental Results of OFDM Rake Reception for Shallow Water Acoustic Communication

Underwater acoustic communication is used for remote control and data transmission in autonomous underwater vehicle (AUV) and underwater sensor networks. It is difficult to keep communication reliability under multipath environment, where a delay wave interferes in a desired wave due to reflections from water bottoms, surfaces, and obstacles. Orthogonal frequency-division multiplexing (OFDM) is attractive for making use of frequency domain equalization (FDE). OFDM inserts a guard interval (GI) into data blocks. A long GI induces a large delay in communication response. We have studied a new scheme of OFDM rake reception to keep stable communication performance even for a short GI. This paper reports experimental results of OFDM rake reception in harbor area comparing with other conventional methods.