In this paper, a Media Access Control (MAC) protocol is investigated for multichannel underwater acoustic sensor networks and a distributed channel allocation scheme is proposed for acoustic nodes equipped with a multichannel bi-directional transceiver. To ensure that a minimum of one channel is allocated for each transmitter-receiver pair, a novel distributed channel allocation scheme, the High Coverage High Fairness (HCHF) algorithm, is proposed. The algorithm requires the exchange of channel sensing information among neighbor nodes at the beginning of each transmission time slot. To compare HCHF and existing schemes, various performance metrics are assessed including spectrum utilization, coverage, fairness, and control packet overhead. Simulation results indicate that the HCHF scheme can improve the coverage and fairness in comparison to other schemes without sacrificing much on the spectrum utilization. The performance improvement of HCHF is constrained by a higher control message overhead, since local packet exchange between neighbor nodes is required to share spectrum sensing information.

Introduction

The deployment of underwater networks is attracting significant interest to monitor subsea infrastructure, and submarine activity. Enabling underwater acoustic sensor networks (UWASNs) is key for ocean monitoring and data collection. For example, commercial and scientific UWASN applications target oil and gas and aquaculture industries and include instrument monitoring, pollution control, climate recording, offshore exploration and pipeline surveillance. Moreover, the Internet of Underwater Things (IoUT) extends the Internet of Things (IoT) to subsea applications, and interconnects a large number of sensors of various types to collect data in a distributed fashion for various applications [1]. However, UWASN impose challenges to the IoUT due to the band-limited underwater acoustic channels. The primary design goal of the proposed underwater wireless network is to exchange sensor information using acoustic nodes (ANs). A multi-hop peer-to-peer network is formed by establishing communication links only between neighboring nodes. Messages are transferred from source to destination by hopping packets from node to node [2]. For this purpose, it is important to define a distributed channel allocation scheme. An important challenge is that the communication resources are limited: acoustic propaga- ∗ Corresponding author. E-mail addresses: h.ghannadrezaii@dal.ca (H. Ghannadrezaii), JBousquet@Dal.Ca (J.-F. Bousquet). tion presents a limited bandwidth and it depends on the geometry of the deployment which varies as a function of time and location [3].