A hybrid MAC protocol with channel-dependent optimized scheduling for clustered underwater acoustic sensor networks

Abstract

We propose a novel optimal time slot allocation scheme for clustered underwater acoustic sensor networks that leverages physical (PHY) layer information to minimize the energy consumption due to unnecessary retransmissions thereby improving network lifetime and throughput. To reduce the overhead and the computational complexity, we employ a two-phase approach where: (i) each member node takes a selfish decision on the number of time slots it needs during the next intra-cluster cycle by solving a Markov decision process (MDP), and (ii) the cluster head optimizes the scheduling decision based on the channel quality and an urgency factor. To conserve energy, we use a hybrid medium access scheme, i.e., time division multiple access (TDMA) for the intra-cluster communication phase and carrier sense multiple access with collision avoidance (CSMA/CA) for the cluster head-sink communication phase. The proposed MAC protocol is implemented and tested on a real underwater acoustic testbed using SM-75 acoustic modems by Teledyne Benthos. Simulations illustrate an improvement in network lifetime. Additionally, simulations demonstrate that the proposed scheduling scheme with urgency factor achieves a throughput increase of 28% and improves the reliability by up to 25% as compared to the scheduling scheme that neither use MDP nor optimization. Furthermore, testbed experiments show an improvement in throughput by up to 10% along with an improvement in reliability.

DCO-MAC: A Hybrid MAC Protocol for Data Collection in Underwater Acoustic Sensor Networks

“…Several MAC protocols intended for multi-hop underwater sensor networks are also proposed. The cluster-based MAC protocol (CH-MAC) [ 16 ] and cluster-based data collection schemes with direct sink access (CDS-DSA) [ 19 ] are both designed for a clustered UASN. In both of the MAC protocols, the transmission is partitioned into two phases, namely the intra-cluster communication phase and the inter-cluster communication phase.…”

Machine learning for wireless communications in the Internet of Things: A comprehensive survey

“…A key functionality of the data link layer is to negotiate the access to the medium by sharing the limited spectrum resources in an ad hoc manner. Traditional MAC protocols designed for WANETs (including IoT networks) include carrier sense multiple access/collision avoidance (CSMA/CA) [183,184], time division multiple access (TDMA) [185,186], code division multiple access (CDMA) [187,188] and hybrid approaches [189,190,191]. Here, we discuss some of the recent efforts to employ ML to enhance the data link layer.…”

Markov Decision Processes With Applications in Wireless Sensor Networks: A Survey

“…This tridiagonal form helps in determining the state at future time slots without specifying the initial state. In a similar context, Jagannath et al [100] introduced a MAC protocol that considers the physical layer parameters for optimizing scheduling decisions. The protocol is designed for underwater WSNs where nodes' battery replacement is a laborious task.…”

“…The proposed backoff algorithm enhances the scalability of conventional MAC protocols by achieving better performance at the increased number of nodes. Unlike [100] which considers a hybrid CSMA/CA and TDMA protocols at different hierarchical levels, Shrestha et al [102] divide the channel access into two periods of contention (CSMA/CA) and contention-free (TDMA) phases. The proposed design is for tackling the problem of poor CSMA/CA's performance (i.e., energy consumption and throughput) when the channel is congested.…”