Securing underwater wireless communication networks

1. Introduction to Underwater Wireless Communication Network

Securing underwater wireless communication networks (UWCNs) are constituted by sensors and autonomous underwater vehicles (AUVs) that interact to perform specific applications such as underwater monitoring (Fig. 1). Coordination and sharing of information between sensors and AUVs make the provision of security challenging. The aquatic environment is particularly vulnerable to malicious attacks due to the high bit error rates, large and variable propagation delays, and low bandwidth of acoustic channels. Achieving reliable intervehicle and sensor-AUV communication is especially difficult due to the mobility of AUVs and the movement of sensors with water currents. The unique characteristics of the underwater acoustic channel, and the differences between underwater sensor networks and their ground based counterparts require the development of efficient and reliable security mechanisms. This article discusses security in UWCNs. It is structured as follows. The following section explains the specific characteristics of UWCNs in comparison with their ground-based counterparts. Next, the possible attacks and countermeasures are introduced. Subsequently, security requirements for UWCNs are described. Later, the research challenges related to secure time synchronization, localization, and routing are summarized. Finally, the article is concluded.

Figure 1. Underwater sensor network with AUVs.

2. CHARACTERISTICS AND VULNERABILITIES OF UWCNs

Underwater sensor networks have some similarities with their ground-based counterparts such as their structure, function, computation and energy limitations. However, they also have differences, which can be summarized as follows.Radio waves do not propagate well underwater due to the high energy absorption of water.Therefore,underwater communications are based on acoustic links characterized by large propagation delays. The propagation speed of acoustic signals in water (typically 1500 m/s) is five orders of magnitude lower than the radio wave propagation speed in free space. Acoustic channels have low bandwidth. The link quality in underwater communication is severely affected by multipath, fading, and the refractive properties of the sound channel. As a result, the bit error rates of acoustic links are often high, and losses of connectivity arise. Underwater sensors move with water currents, and AUVs are mobile. 

3. ATTACKS  ON UWCNS AND COUNTERMEASURES

Both intervehicle and sensor-AUV communications can be affected by denial-of-service (DoS)attacks. Next, we summarize typical DoS attacks, evaluate their dangers, and indicate possible defenses to muffle their effects.

3.1 JAMMING

A jamming attack consists of interfering with the physical channel by putting up carriers on the frequencies neighbor nodes use to communicate.Since underwater acoustic frequency bands are narrow (from a few to hundreds of kilohertz), Securing underwater wireless communication networks are vulnerable to narrowband jamming.

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