MOBICOM

Autonomous underwater vehicles (AUVs) typically communicate with scientists on the surface over an unreliable wireless channel. The challenges of underwater acoustic communication result in very low data throughput. While there are several examples of ...

The key aspect in the design of any contention-based medium access control (MAC) protocol is the mechanism to measure and resolve simultaneous contention. Generally, terrestrial wireless MACs can only observe success or collision of a contention attempt ...

Time synchronization is an essential service in underwater networks, required for many functionalities such as MAC, sleep-scheduling, localization, and time-stamping of sensor events. However, there exist two fundamental challenges to underwater ...

In this paper, we process channel Signal-to-Noise-Ratio time series gathered in the proximity of the Pianosa island, Italy, in Summer 2009. These traces are used to model the performance of capacity-achieving code ensembles as employed in an Incremental ...

Channel variability and a high level of ambient noise lead to significant probability of packet loss in many underwater networks. Techniques based on acknowledgements and re-transmissions (such as ARQ) can be used to build robust networks over the ...

In this paper, we investigate OFDM based MAC protocols for underwater acoustic networks. Due to the severe multi-path effects of underwater acoustic channels, the guard time between OFDM blocks becomes significant, which greatly degrades the system ...

Nature has had millions of years to develop and optimize life in the ocean. Nocturnal oceanic animals and those that live at depth cannot rely upon optical notions of vision to navigate, hunt, or avoid predators. Instead, many rely upon an ...

Mapping and exploration of closed fluid tanks, such as nuclear waste storage tanks and water sewage treatment ponds, by a swarm of underwater robots requires them to be aware of their positions, as they traverse the depths of the tank. This paper ...

Multi-carrier modulation (MCM) has a significant potential for achieving high bit rates over multipath-distorted (frequency selective) channels and provides both power and processing efficiency. Each frequency channel has relatively low delay spread ...

We propose a hierarchical underwater acoustic sensor network architecture in which the sensors and the collector stations operate in distinct layers. The hierarchical architecture is motivated by the property of the acoustic underwater transmission ...

Signal scaling due to Doppler in underwater acoustic communications results in inter-carrier interference (ICI) and severely degraded detection performance in OFDM based systems in the absence of interference mitigation. Using a recently proposed ...

To fully understand the ocean environment requires sensing the full water column. Utilizing a depth adjustment system on an underwater sensor network provides this while also improving global sensing and communications. This paper presents a depth ...

Researchers are working on using freshwater mussels as biological sensors. A sensor placed on the mussel detects the mussel's rhythmic opening and closing, or gape. Changes in the gape can indicate changes in the mussel's environment. We plan to attach ...

Due to high energy efficiency and fast data query, data-centric storage (DCS) is a promising technique for underwater acoustic sensor networks (UASN). However, the harsh sea environment poses new challenges to the design of underwater DCS protocols. ...

Recent years witnessed an increasing requirement of marine missions like oceanographic investigation, environmental monitoring, underwater structure inspection and sea bottom resource exploitation, which urged the R&D of high performance underwater ...

Deep water horizontal channels usually have very long delay spreads relative to shallow water channels. The delay spread can be several hundreds of milliseconds, which covers several blocks of orthogonal frequency division multiplexing (OFDM) ...

In designing an underwater acoustic sensor network, the main bottleneck a field designer faces is the acoustic communications range of the sensors. Since communications is done at relatively high frequencies, as compared with frequencies emitted by ...

UnderWater Acoustic Sensor Networks (UW-ASNs) [1] are envisioned to enable applications for oceanographic data collection, environmental monitoring, navigation, and tactical surveillance. Geocasting, which is the transmission of packet(s) to nodes ...

It is well acknowledged that CDMA scheme could achieve higher system capacity in cellular type Radio Frequency networks (RFN) than either TDMA or FDMA, since the system capacity of TDMA or FDMA is resource (bandwidth) restricted, while the one of CDMA ...