(U) In the context of an information-based society the ability to reliably retrieve, transfer and process large quantities of data in a timely fashion becomes a critical technology issue. In the context of integrating submarine offboard sensors and physically supporting data connectivity with terrestrial networks: reliable, high bandwidth communications ranks as an extremely difficult technical...

A resurgence is occurring in the area of underwater laser communications. While acoustic systems are currently the more mature technology, they are ultimately band-limited to sub-MHz type data rates due to the frequency dependent absorption of acoustic energies in water. Advances in fiber optic and free space links have shown promise for optical links to provide data rates in excess of a gigabi...

The maximum potential for underwater exploration rests within the use of multiple Autonomous Underwater Vehicles (AUVs) and tasks involving human diver-AUV coordination. Such missions are gaining increasing popularity with the advent of better control mechanisms and availability of acoustic modems. However, high costs and the lack of useful tools to simulate multiAUV tasks have hindered the ful...

There has been a growing interest to incorporate Unmanned Underwater Vehicles (UUVs) in various military applications. UUVs can be easily deployed in an area of interest such as offshore fleet operating regions and littoral penetration zones to collect critical data. In many military scenarios, collected sensor data have to be transmitted to a host station which could be a land base station, a ...

A digital modulation method using Chirp-Slope Keying (CSK) is developed for coherent underwater acoustic communications. Effective signal detection is a critical stage in the implementation of any communications system; we will see that CSK solves some significant challenges to reliable detection. This thesis is primarily based on analyzing the effectiveness of CSK through simulations using Mat...

It is well known that a Code Division Multiple Access (CDMA) scheme achieves higher user density in a cellular network with radio frequency signal in a terrestrial environment than either Time Division Multiple Access (TDMA) or (Frequency Division Multiple Access) FDMA could. The concept of a cellular (cluster) network has been introduced for underwater acoustic communications. However, its per...

Recent technological improvements and application opportunities have fueled increased interest in the development and deployment of underwater acoustic sensor networks. Deployment efforts have been impeded by the prohibitive monetary cost and high power consumption of existing acoustic hardware. Alternately, we propose underwater networks that rely on widely available speakers and microphones i...

Underwater acoustic (UWA) communications have been widely used but greatly impaired due to the complicated nature of underwater environment. In order improve UWA communications, modeling and understanding channel is indispensable. However, there exist many challenges high uncertainties environment lack real-world measurement data. this work, capability reservoir computing deep learning has expl...

Underwater acoustic (UWA) communications face many challenges, such as large multipath delay, severe fading and the time-varying distortions. Chaotic modulations have shown advantages in UWA communications, but reliability of current chaotic is still not guaranteed. In this paper, a short-length protograph low-density parity-check (P-LDPC) code design framework for differential bit-interleaved ...

underwater acoustic wireless sensor network (uawsn) use acoustic signalsto transmit data. acoustic signals in underwater environment have high bit errorrate, long propagation delay and limited bandwidth. another constraint in uwasnis energy. due to these constraints, design of energy and bandwidth efficient andpropagation delay aware mac protocol is a great challenge in uwasn.underwater sensor ...