Abstract
Underwater Sensor Networks (UWSNs) utilise acoustic waves with comparatively lower loss and longer range than those of electromagnetic waves. However, energy remains a challenging issue in addition to long latency, high bit error rate, and limited bandwidth. Thus, collision and retransmission should be efficiently handled at Medium Access Control (MAC) layer in order to reduce the energy cost and also to improve the throughput and fairness across the network. In this paper, we propose a new reservation-based distributed MAC protocol called ED-MAC, which employs a duty cycle mechanism to address the spatial-temporal uncertainty and the hidden node problem to effectively avoid collisions and retransmissions. ED-MAC is a conflict-free protocol, where each sensor schedules itself independently using local information. Hence, ED-MAC can guarantee conflict-free transmissions and receptions of data packets. Compared with other conflict-free MAC protocols, ED-MAC is distributed and more reliable, i.e., it schedules according to the priority of sensor nodes which based on their depth in the network. We then evaluate design choices and protocol performance through extensive simulation to study the load effects and network scalability in each protocol. The results show that ED-MAC outperforms the contention-based MAC protocols and achieves a significant improvement in terms of successful delivery ratio, throughput, energy consumption, and fairness under varying offered traffic and number of nodes.
Highlights
Underwater sensor networks (UWSNs) have a promising future in the area of information collection with increasingly more applications in recent years
The simulation results within two parameters studies the traffic effect and network scalability in every protocol and shows how these three Medium Access Control (MAC) protocols perform in practical underwater networks
Outperforms that of other two MAC protocols, T-Lohi and UWAN-MAC. This is because Efficient Depth-based MAC protocol (ED-MAC) has the ability to address the hidden node and the spatio-temporal uncertainty problems which cannot be detected by UWAN-MAC protocol resulting in more packet loss and collisions
Summary
Underwater sensor networks (UWSNs) have a promising future in the area of information collection with increasingly more applications in recent years. To enable collision-free scheduling of transmissions and receptions, these problems should properly be addressed To solve these issues, some handshake-based MAC protocols have been proposed [6,12]. While the above-mentioned classes of MAC protocols are expected to achieve high performance, some recent observations, have reported that long propagation delay, narrow bandwidth, and high bit error rate make the contention-based MAC protocols costly [18,19,20] Both handshake-based and random access-based MAC protocols are not as efficient as expected [19,20,21]. ED-MAC schedules the transmissions and receptions of data packets at both the sender and receiver sides to achieve the above-mentioned objectives, and to address the spatial-temporal uncertainty and hidden terminal problems.
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