Multi-Channel MAC Protocol based on Dynamic Time Slot Allocation for Underwater Sensor Networks

Abstract

The underwater sensor networks (USNs) are becoming increasingly important in ocean exploration.Compared with wireless networks, USNs have long propagation delay of acoustic signals, which pose challenges to the design of medium access control (MAC) protocol and degrade network performance.In order to improve network performance, EM-MC MAC protocol was proposed.The EM-MC protocol uses a single electromagnetic (EM) channel to reserve data transmissions, and acoustic channels to transmit data packets.The EM-MC protocol does not work well in environments where node configurations change dynamically because the number of time slots to reserve data transmissions on the EM channel is fixed.To solve this problem, we propose a new MAC protocol, which allocates time slots dynamically according to node configurations.In the proposed protocol, time is divided into superframes.Time slots are allocated to each sensor node based on the node configuration at the start time of each superframe.Performance evaluation is conducted using simulation, and confirms that the proposed protocol outperforms the previous protocol in terms of throughput.