Adaptif OFDM tabanlı akustik su altı iletimi: Sistem tasarımı ve deneysel doğrulama

In this study, we design and implement an adaptive Underwater Acoustic (UWA) orthogonal frequency division multiplexing (OFDM) system employing adaptive modulation and transmit power. Recently, UWA communications gain more attractions as there has been a growing interest in exploring the communications possibilities for underwater applications such as oil field monitoring, oceanographic data collection, maritime archaeology and disaster prevention. However, the harsh characteristic of underwater environments imposes various difficulties for communication in this medium. Thus, proposing a reliable UWA communication system which has a high data rate can improve these applications performance significantly. Since UWA communications suffer from low data rates, we propose an adaptive OFDM communication system to support higher data rates over UWA channel. OFDM is an attractive technique for underwater channels due to the fact that inter-symbol-interference resulted from frequency selective channels can be removed completely. Additionally, adaptive communications achieve significant improvements in transmission data rate. For the sake of implementation, we take advantages of LabVIEW software to generate OFDM blocks. The generated data is transmitted to the receiver side with the aid of Software defined radios (USRPs) and acoustic front-ends. The received data at the acoustic hydrophones are transferred to the USRPs and then processed in LabVIEW for information detection. We conduct our experiments at the pool to investigate the performance of the proposed system over a real UWA channel.