Hovannes Kulhandjian

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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 new secure underwater acoustic communication scheme designed to let a user (Alice) transmit a confidential message to another user (Bob) in the presence of an eavesdropper (Eve). A typical approach in conventional wireless physical-layer security is to rely on a friendly jammer to jam Eve through artificial noise (AN). Instead, for the first(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)
In this paper, we present our ongoing work on developing a reconfigurable underwater networking testbed based on the Teledyne Benthos Telesonar SM-75 modem. The testbed is designed with the objective of allowing researchers and developers to advance research activities in the field of underwater networking and communications through a flexible testbed(More)
The performance of multi-hop underwater acoustic network is known to be limited by the long propagation delays and by the limited bandwidth of the underwater acoustic (UW-A) channel. Recent work on analog network coding (ANC) has shown that significant throughput gains can be achieved in multi-hop wireless networks. However, implementing ANC for UW-A(More)
We propose ANC-CDMA, a CDMA-based analog network coding scheme for underwater acoustic sensor networks (UW-ASNs) that can significantly improve the underwater acoustic channel utilization. First, we analyze a unidirectional multihop network, in which two acoustic nodes separated by two hops are assigned the same code-division channel (i.e., spreading code)(More)
We analyze the statistical channel properties of short to very short-range shallow water communication environments based on real channel measurements taken in a water-tank, a swimming pool, very shallow and shallow lakes. More specifically, we estimate the channel impulse response (CIR), the probability density function (PDF) of channel fading and fit to(More)
Localization and time synchronization are both essential services for Internet-connected underwater acoustic testbeds. Although the two are mutually coupled, they are often treated separately. We propose a new low-cost distributed networked localization and time synchronization framework for underwater acoustic sensor networks. The proposal is based on(More)
We present our ongoing work on developing a reconfigurable underwater acoustic (UW-A) networking testbed based on the Teledyne Benthos Telesonar SM-75 modem [1]. The SM-75 modem is customized to allow the research community to conduct advanced networking and communication experiments as follows. First, a programmable Gumstix [2] network processor is(More)
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