As underwater communications adopt acoustics as the primary modality, we are confronting several unique challenges such as highly limited bandwidth, severe fading, and long propagation delay. To cope with these, many MAC protocols and PHY layer techniques have been proposed. In this paper, we present a research platform that allows developers to easily implement and compare their protocols in a...

In Underwater Sensor Networks (UWSNs), sensor nodes have limited energy resource and consume a lot of power during message transmission. Since expensive transmitting power consumption is an inevitable feature of underwater acoustic transmission, to extend network operation time, it is desirable for nodes to avoid energy wastage resulting from transmission collisions. Enabling nodes to use multi...

The properties of underwater acoustic channel are quite different from those of terrestrial wireless sensor networks. There are many challenges to design an efficient media access control (MAC) protocol for underwater acoustic sensor networks (UWASNs). In order to overcome the long propagation delay and low available bandwidth of UWASNs, an enhanced dynamic token protocol (EDTP), is proposed in...

The principles of sensor networks—low-power, wireless, in-situ sensing with many inexpensive sensors—are only recently penetrating into underwater research. Acoustic communication is best suited for underwater communication, since other methods (optical and radio) attenuate very quickly. Yet acoustic propagation is five orders-ofmagnitude slower than RF, so propagation times stretch to hundreds...

This paper is focused on the description of the physical layer of a new acoustic modem called ITACA. The modem architecture includes as a major novelty an ultra-low power asynchronous wake-up system implementation for underwater acoustic transmission that is based on a low-cost off-the-shelf RFID peripheral integrated circuit. This feature enables a reduced power dissipation of 10 μW in stand-b...

Underwater Wireless Sensor Networks (UWSNs) can be used in ocean exploration and lake pollution monitoring. They use acoustic media to achieve sensor communications. UWSNs are essentially different from terrestrial RF-based sensor networks due to its highly variable, long propagation delay, and mobility nature. In this paper, we first describe our experimental design of low-cost underwater sens...

In Underwater Acoustic Sensor Networks (UASN) designing Medium Access Control (MAC) protocol is a challenging issue. This is due to low bandwidth and high propagation delay in UASN. This paper proposes a MAC protocol for UASN called Aloha with Virtual Back off Algorithm (AlohaV). The VBA approach is the collision avoidance mechanism for wireless networks. In this proposed work we use VBA with n...

Considering the energy constraint for fixed sensor nodes and the unacceptable long propagation delay, especially for latency sensitive applications of underwater acoustic sensor networks, we propose a MAC protocol that is latency-optimized and energyefficient scheme and combines the physical layer and the MAC layer to shorten transmission delay. On physical layer, we apply convolution coding an...

In this chapter, we focus on acoustic underwater networks, which utilize acoustic communication links to communicate between the nodes. It is wellknown that RF signals do not propagate well underwater, and the optical signals [1] are useful for short distances and under clear water propagation conditions. For long distances, the Navy has utilized acoustic communication. More recently, there has...