A High-throughput routing metric for multi-hop Underwater Acoustic Networks q Saiful Azad a , Khandaker Tabin Hasan a , Dip Nandi a , Al-Sakib Khan Pathan b,⇑ a Department of Computer Science, American International University – Bangladesh (AIUB), Kemal Ataturk Avenue, Banani, Dhaka 1213, Bangladesh b Department of Computer Science, International Islamic University Malaysia, Kuala Lumpur, Malaysia article info Article history: Received 1 September 2014 Received in revised form 15 March 2015 Accepted 16 March 2015 Keywords: Underwater Acoustic Networks Routing Metrics CMAS abstract In most wireless network architectures, a routing metric plays an important role for a rout- ing protocol to select suitable paths (or, links) for communications. An inefficient routing metric may increase overall transmission cost per packet by selecting lossy links and thereby may lead to poor throughput. Underwater Acoustic Networks (UANs), where most of the nodes operate on battery power, prefer topology-based routing metrics over active probing based routing metrics. Considering this fact, in this paper, we investigate the per- formance of various topology-based routing metrics over UAN-architecture. We then apply the acquired knowledge to design a new routing metric called Cubic Min to Avg Signal-to- Noise Ratio (CMAS), which is capable of selecting high-throughput links. We evaluate the performance of the proposed metric with other available topology-based routing metrics in underwater scenario. Simulation results demonstrate that the proposed metric attains sig- nificantly higher throughput than that of the other compared metrics. Ó 2015 Elsevier Ltd. All rights reserved. 1. Introduction In the recent years, underwater acoustic communication has received immense attention from the researchers, industries, and various militaries due to its current and future applications, like oceanography, pollution monitoring, offshore explo- ration, disaster prevention, navigation assistance, monitoring, coastal patrol and surveillance, etc. [1,2]. These seasonable applications are encouraging people from different corners of the globe to invest their valuable efforts in the development of this emerging field of communication. Unlike any terrestrial wireless network, acoustic signals are preferred in Underwater Acoustic Networks (UANs) over electro-magnetic or light signals due to large transmission range. However, since the transmission speed of an acoustic signal is very limited which is several magnitudes lower than electro-magnetic signals, UANs experience higher propagation delay. Moreover, an underwater channel faces higher bit error rate due to multi-path, fading, formation of shadow zones, and refractive properties of the sound channel [2]. Furthermore, limited bandwidth, limited energy and impact of the environment over channel make underwater communication more challenging than its other wired or wireless network counterparts. In such a challenging environment, selection of a suitable high throughput routing metric plays an important role in multi-hop communication. Fig. 1 shows a typical model of an UAN. The term, ‘‘AUV’’ in the figure means Autonomous Underwater Vehicle. An AUV is basically a robot (unmanned underwater http://dx.doi.org/10.1016/j.compeleceng.2015.03.020 0045-7906/Ó 2015 Elsevier Ltd. All rights reserved. q Reviews processed and recommended for publication to the Editor-in-Chief by Associate Editor Dr. M. Shadaram. ⇑ Corresponding author. E-mail addresses: sazadm684@aiub.edu (S. Azad), tabin@aiub.edu (K.T. Hasan), dip.nandi@aiub.edu (D. Nandi), sakib@iium.edu.my, sakib.pathan@gmail. com (A.-S.K Pathan). Computers and Electrical Engineering 44 (2015) 24–33 Contents lists available at ScienceDirect Computers and Electrical Engineering journal homepage: www.elsevier.com/locate/compeleceng