An Efficient Scalable Scheduling MAC Protocol for Underwater Sensor Networks

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.

A Collision-Free Hybrid MAC Protocol Based on Pipeline Parallel Transmission for Distributed Multi-Channel Underwater Acoustic Networks

“…Many TDMA protocols used the time domain parallel transmission to optimize their time slot allocations [6][7][8][9][10][11][12]. Some of them also made use of the network topology to reuse some time slots [8][9][10][11][12], which can be regarded as passive space domain parallel transmission. Some information such as propagation delay, link attenuation or node location needed to be known prior for calculating the communication resource in these protocols.…”

“…In the contention-free MAC protocols, because CDMA and FDMA can provide each node an independent channel, which means that nodes can send data packets whenever needed, the researches on parallel transmission were mostly focused on time division multiple access (TDMA). Time and space domain parallel transmission opportunities were often used to optimize the TDMA time slot allocation [6][7][8][9][10][11][12]. Because no control information is needed in TDMA, the design of parallel transmission is simplified to the question of static communication resource allocation, which can be efficiently solved by many mathematical tools and methods.…”

A Stateless Opportunistic Routing Protocol for Underwater Sensor Networks

“…In other words, argmax gives a node at which EPA is maximised. The expected packet advancement of each neighbouring node can be measured by [50] = × Δ (19) where Δ is the depth difference between a node and its neighbouring node, and is the packet error probability over the distance between these two nodes. Based on this metric, the neighbouring node which can simultaneously maximise packet advancement and packet delivery probability is selected as the best candidate node.…”

“…Low available bandwidth, slow propagation speed, ineffectiveness of Global Positioning System (GPS), and a lossy environment are a number of such restrictions [14][15][16]. Finally, there are some restrictions on the energy consumption of underwater sensors due to the difficulties of replacing or recharging their batteries, and also using the acoustic communication for transmitting the packets [17][18][19]. Therefore, designing an efficient void-handling technique to improve the greedy routing protocol efficiency in UWSNs is crucial.…”

DCN-MAC: A Dynamic Channel Negotiation MAC Mechanism for Underwater Acoustic Sensor Networks

“…However, such reservation-based protocols are often not adapt to the dynamic adjustment of the network, including the dynamic traffic and the dynamic topology of nodes in the network. Although some protocols, such as ED-MAC [14], add a sub-slot mechanism to ensure that newly joined nodes access the network, there is still consumption of sub-slot resources for dynamic burst traffic conditions between multiple nodes. In comparison, contention-based MAC protocols based on random access or handshake mechanisms are more suitable for network dynamics.…”