Emrecan Demirors

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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)
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)
It is well known that electromagnetic radio-frequency (RF) waves that are the basis of most commercial wireless technologies are largely unsuitable to interconnect deeply implanted medical devices. RF waves are in fact absorbed by aqueous biological tissues and prone to malicious jamming attacks or to environmental interference from pervasively deployed RF(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)
We review and discuss the challenges of adopting software-defined radio principles in underwater acoustic networks, and propose a software-defined acoustic modem prototype based on commercial off-the-shelf components. We first review current SDR-based architectures for underwater acoustic communications. Then we describe the architecture of a new(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)
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)
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)
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)
This paper introduces innovative technology development that will improve performance of next-generation cognitive wireless networking among space, air, and ground assets. The paper describes methods to develop a system where cognitive users transmit wideband spread-spectrum signals that are designed to adaptively avoid the interference dynamics of the(More)