An Eficient Energy Two Mode Error Correction Technique in Underwater Wireless Sensor Networks Amar Elyas Babiker, M. Nordin B. Zakaria Computer and Information Science Dept Universiti Teknologi PETRONAS 31750 Tronoh, Perak, Malaysia ammaralyas@gmail.com Abstract- Research in underwater acoustic networks has developed quickly to support large variety of applications such as mining equipment and environmental monitoring. As in terrestrial sensor networks; reliable data transport is demanded in underwater sensor networks. The energy eiciency of error correction techniques should be considered because of the severe energy constraints of underwater wireless sensor networks. FEe and ARQ are the two main error correction techniques in underwater networks. In this paper, a mathematical energy eiciency analysis for FEe and ARQ techniques in underwater environment is done based on communication distance, packet size and wind speed. And a comparison between FEe and ARQ in terms of energy eiciency is done, it was found that energy eiciency of both techniques increases with increasing packet size in short distances, but decreases in longer distances. There is also a cutof distance below which ARQ is more energy eicient than FEe, and ater which FEe is more energy eficient than ARQ. Wind speed has great effect on energy eiciency and on cutoff distance for both techniques. Based on this analysis an eicient energy two mode error correction technique is proposed, this technique depends on RTT, distance, packet size, and the energy level in the nodes to determine where and how error can be corrected. Kywords- ARQ; FEC; energy eiciency, error correction techniques, underwater communications I. INTRODUCTION Underwater wireless sensor networks have received growing interest in the last few decades [1, 2, 3, 4]. As in terrestrial sensor networks; in most applications, reliable data transport is demanded in underwater sensor networks [5]. FEC and ARQ are the two main error correction techniques that guarantee the reliability of data transmission in underwater acoustic links [2, 6, 7]. To design a good reliable data transport protocol,a traditional concen is the energy eiciency issue, since many applications require nodes to operate underwater for long periods without recharging their batteries. It is also hard to recharge or replace batteries in some aquatic environments [5, 8]. 978-1-4244-6716-7110/$26.00 ©2010 IEEE In this paper we analyze the energy eficiency of FEC and ARQ in underwater wireless sensor networks. Based on this analysis energy eicient two mode error correction technique is proposed,this technique depends on distance,RTT,packet size, and the energy level on the nodes to determine where and how error can be corrected. The analysis start by calculating the minimum AN factor in terms of requency irst, then a mathematical analysis for energy eiciency for ARQ and FEC in underwater are presented for diferent distance,packet size, and wind speed. ARQ is compared with FEC in terms of energy eiciency, and the status where each one outperforms the other is presented. Based on this the two mode error correction techniques is proposed. To the best of our knowledge, this paper is the irst which compare ARQ with FEC techniques in terms of energy eficiency in underwater environments using diferent variable parameters. The proposed technique is the irst which uses network conditions to determine where and how the error will be corrected based on this energy analysis. The rest of the paper is organized as follows: literature is reviewed on section II, underwater propagation model is given in section III, mathematical energy eficiency analysis for both error correction techniques is provide in section IV,in section V we present energy eficiency results and analysis. In section VI the two mode error correction technique is presented. In section VII the paper is concluded and the uture work is presented. II. LITERATURE REVEW According to [9, 10], conventional end-to-end reliability solutions (TCP) are inapplicable in underwater ield. The primary objective in transport protocol is to save scarce node resources and increase network eiciency. Due to [9] In underwater packet losses may occur due to high bit error rate or due to network congestion, so rate based mechanism (assume packet loss is due to congestion only) is not suitable in underwater. Also RTT estimation is not accurate, so windows based mechanism is not suited. In [9] they propose integration of unctionality between transport and data lik layer to make use of the information about the condition of the variable underwater channel which is known only at physical 580