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The field of underwater acoustic networking is growing rapidly thanks to the key role it plays in many military and commercial applications. Among these are disaster prevention , tactical surveillance, offshore exploration, pollution monitoring and oceanographic data collection. The underwater acoustic propagation channel presents formidable challenges ,(More)
This article describes the design of a custom software-defined modem with adaptive physical layer for underwater acoustic (UWA) communications. The modem consists of a commercial software-defined radio (SDR) interfaced with a wideband acoustic transducer through amplifying circuitry. With this custom-built platform, we focus on the unique physical layer(More)
—We propose a receiver configuration and we develop a software-defined-radio testbed for real-time cognitive underwater multiple-access communications. The proposed receiver is fully reconfigurable and executes (i) all-spectrum cognitive channelization and (ii) combined synchronization, channel estimation , and demodulation. Online (real-time) experimental(More)
Existing commercial wireless systems are mostly hardware-based, and rely on closed and inflexible designs and architectures. Moreover, despite recent significant algorithmic developments in cross-layer network adaptation and resource allocation, existing network architectures are unable to incorporate most of these advancements. While software-defined radio(More)
As of today, Underwater Acoustic Networks (UANs) are heavily dependent on commercially available acoustic modems. While commercial modems are often able to support specific applications, they are typically not flexible enough to satisfy the requirements of next-generation UANs, which need to be able to adapt their communication and networking protocols in(More)
We propose a novel optimal time slot allocation scheme for clustered underwater acoustic sensor networks that leverages physical (PHY) layer information to minimize the energy consumption due to unnecessary retransmissions thereby improving network lifetime and throughput. To reduce the overhead and the computational complexity, we employ a two-phase(More)
—We create new software signal processing blocks and provide transmitter and receiver designs in GNU Radio and MATLAB to experimentally demonstrate the theoretical concepts of all-spectrum cognitive channelization in a software-defined-radio (SDR)-based testbed. Three low-cost, SDR nodes (USRPN-210) are deployed in an indoor, multipath-fading, lab(More)
—In this paper we design, implement, and experimentally evaluate a wireless software-defined radio platform for cognitive channelization in the presence of narrowband or wideband primary stations. Cognitive channelization is achieved by jointly optimizing the transmission power and the waveform channel of the secondary users. The process of joint resource(More)