Contention analysis of MAC protocols that count (original) (raw)
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International Journal of Distributed Sensor Networks, 2015
Due to the limited capacity and high propagation delay of underwater communication channels, contention-based media access control (MAC) protocols suffer from a low packet delivery ratio (PDR) and a high end-to-end (E2E) delay in underwater acoustic sensor networks due to the reliance on packet retransmission for reliable data delivery. In order to address the problem of low performance, we propose a novel adaptive retransmission scheme, named ARS, which dynamically selects an optimal value of the maximum number of retransmissions, such that the successful delivery probability of a packet is maximized for a given network load. ARS can be used for various contention-based protocols and hybrid MAC protocols that have contention periods. In this paper, ARS is applied to wellknown contention-based protocols, Aloha and CSMA. Simulation results show that ARS can achieve significant performance improvement in terms of PDR and E2E delay over original MAC protocols.
T-Lohi: A New Class of MAC Protocols for Underwater Acoustic Sensor Networks
2008
This paper introduces T-Lohi, a new class of distributed and energy-efficient media-access protocols (MAC) for underwater acoustic sensor networks (UWSN). MAC design for UWSN faces significant challenges. For example, acoustic communication suffers from latencies five orders-ofmagnitude larger than radio communication, so a naive CSMA MAC would require very long listen time resulting in low throughput and poor energy efficiency. In this paper, we first identify unique characteristics in underwater networking that may affect all MACs, such as space-time uncertainty and deafness conditions. We then develop T-Lohi employing a novel tone-based reservation mechanism that exploits space-time uncertainty and high latency to detect collisions and count contenders, achieving good throughput across all offered loads. It employs our low-power wake-up receiver to significantly reduce energy consumption. Finally, we evaluate design choices and protocol performance through extensive simulation. The results show that the energy cost of packet transmission is within 3-9% of optimal, that our protocols achieve good channel utilization, within 30% of the theoretical maximum. We also show that our protocols are stable and fair under both low and very high offered loads.
Comparative Analysis of MAC Protocols and Strategies for Underwater Applications
Wireless Personal Communications, 2016
This research focuses on the comparison of the throughput performance of MAC protocols designed for underwater acoustic networks. Our emphasis was to study the key features of the existing MAC protocols for underwater acoustic communications and provide analytical analysis where feasible. We compared some selected underwater MAC protocols like UAN-ALOHA, CSMA, MACA, MACA-EA and S-FAMA and analyzed their throughputs. We chose to evaluate possible improvements in the throughput of S-FAMA by using the retry mechanism. We found the retry mechanism only showed marginal improvement in the throughput. The proposed mechanisms may not have practical efficacy, however, this mechanism may be helpful in saving energy of the sensor nodes by preventing the repetition of the entire transmission cycle.
Aloha-Based MAC Protocols with Collision Avoidance for Underwater Acoustic Networks
2007
Unlike terrestrial networks that mainly rely on radio waves for communications, underwater networks utilize acoustic waves, which have comparatively lower loss and longer range in underwater environments. However, the use of acoustic waves pose a new research challenge in the networking area. While existing network schemes for terrestrial sensor networks are mainly designed for negligible propagation delay and high data rate, underwater acoustic communications are characterized by high propagation delay and low data rate. These terrestrial schemes, when directly applied to the underwater channel, will under-utilize its already limited capacity. We investigate how the underwater channel's throughput may be enhanced via medium access control (MAC) techniques that consider its unique characteristics. Specifically, we study the performance of Aloha-based protocols in underwater networks, and propose two enhanced schemes, namely, Aloha with collision avoidance (Aloha-CA), and Aloha with advance notification (Aloha-AN), which are capable of using the long propagation delays to their advantage. Simulation results have shown that both schemes can boost the throughput by reducing the number of collisions, and, for the case of Aloha-AN, also by significantly reducing the number of unproductive transmissions.
Comparing underwater MAC protocols in real sea experiments
Computer Communications, 2015
Underwater acoustic networks (UANs) have drawn significant attention from both academia and industry in recent years. Even though a number of underwater MAC protocols have been proposed and studied based on simulations and theoretical analysis, few work has been conducted to test these protocols in multi-hop real sea experiments. Due to the complex multipath environment, fast varying acoustic channel and heterogenous link condition, it is difficult for existing network simulators to evaluate the performance of MAC protocols in the real world. This paper presents the results of a multi-hop sea experiment comparing three representative MAC protocols: random access based UW-Aloha, handshaking based SASHA, and scheduling based PMAC. From the experiments, we identified several problems that have never been well studied before, such as heterogeneous packet delivery, temporal and spatial transmission range uncertainty, multi-hop interference and delayed data transmissions. Discussions are provided based on the new discoveries, in hopes of giving some meaningful insights into the practical MAC design for real multi-hop networks.
Performance evaluation of underwater MAC protocols: From simulation to at-sea testing
OCEANS 2011 IEEE - Spain, 2011
Many MAC protocols have been proposed for underwater sensor networks, usually variants of wellknown terrestrial approaches. Although performance comparisons among different MAC protocols have been estimated by simulations, e.g. [1], [2], no extensive comparison has yet been performed by means of at-sea experiments.
A Comparative Analysis on Selective Mac Protocols for Underwater Wireless Sensor Network
2016
The underwater sensor communication supports a large number of applications, like, oceanographic data collection, pollution monitoring, offshore exploration, disaster prevention, navigation and tactical surveillance data collection. In Underwater Acoustic Sensor Network (UASN), sensor nodes are deployed to a given area to do collaborative work. Underwater communication relies mainly on acoustic waves. Limited bandwidth, high propagation delay, high bit error rates and limited battery power etc are the major communication challenges for underwater communications. These issues pose great challenges in underwater Media Access Control (MAC) protocol design. Although many novel protocols are designed for terrestrial MAC protocols but they perform inefficiently when deployed directly in an underwater environment. On the other hand, a range of MAC protocols has been explored in underwater networks to meet certain communication criteria. In this paper, several contentions based and contenti...
Comparing underwater MAC protocols in real sea experiment
2013
Underwater acoustic networks (UANs) have drawn significant attention from both academia and industry in recent years. Even though many underwater MAC protocols have been proposed and studied based on simulations and theoretical analysis, few work has been conducted to test and evaluate these protocols in a multi-hop real sea experiment. Due to the harsh acoustic channel condition caused by complex multi-path environment, fast varying acoustic channel and heterogenous channel quality, current simulators can hardly tell us how the protocols work in the real world. Along this direction, we conduced real sea experiments at Atlantic Ocean with 9 nodes deployed forming a multi-hop string network. In this experiment, the performance of three representative MAC protocols, random access based UW-Aloha, handshaking based SASHA, and scheduling based pipelined transmission MAC (PTMAC) are compared and analyzed at both packet behavior and node behavior levels. The end-to-end performance of these three protocols are also tested and studied in terms of throughput, delay, and packet delivery ratio. From field experiment results, the high packet loss rate and significant channel asymmetry, temporal and spatial transmission range uncertainty and delayed data transmissions are discovered to have evidential effects on the MAC performance. We provide some inspirations to address these observed issues in MAC design for real multi-hop networks.
DAMAC: A Delay-Aware MAC Protocol for Ad Hoc Underwater Acoustic Sensor Networks
Sensors
In a channel shared by several nodes, the scheduling algorithm is a key factor to avoiding collisions in the random access-based approach. Commonly, scheduling algorithms can be used to enhance network performance to meet certain requirements. Therefore, in this paper we propose a Delay-Aware Media Access Control (DAMAC) protocol for monitoring time-sensitive applications over multi-hop in Underwater Acoustic Sensor Networks (UASNs), which relies on the random access-based approach where each node uses Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) to determine channel status, switches nodes on and off to conserve energy, and allows concurrent transmissions to improve the underwater communication in the UASNs. In addition, DAMAC does not require any handshaking packets prior to data transmission, which helps to improve network performance in several metrics. The proposed protocol considers the long propagation delay to allow concurrent transmissions, meaning nodes are s...
Slotted FAMA: a MAC protocol for underwater acoustic networks
2006
Long propagation delays and low bit rates of underwater acoustic networks make these systems fundamentally different from the packet radio networks. As a consequence, many of the network protocols designed for radio channels are either not applicable, or have extremely low efficiency over underwater acoustic channels. These facts necessitate a dedicated design of protocols for an underwater acoustic network.