Synchronous Medium Access Control Protocol Research Articles

Collision-free distributed MAC protocol for passive optical intra-rack data center networks

In this paper, we present a distributed medium access control (MAC) protocol and a network architecture suitable for optical intra-rack data center networks (DCNs). The intra-rack communication is performed using passive optical components, over four data wavelength division multiplexing (WDM) channels of either 40 or 100 Gbps each, keeping low power consumption. On the other hand, the inter-rack communication is performed over a separate network through upper layer routers. In this study, we focus only on the intra-rack communication. We introduce an intra-rack DCN (IR-DCN) architecture that works in the optical domain, and two IR-DCN configurations with different total nominal capacity: 160 and 400 Gbps, respectively. Also, we propose a synchronous pre-transmission coordination fair access intra-rack MAC (intra-MAC) protocol taking into account the traffic characteristics and priority classes within existing DCNs. The proposed intra-MAC protocol totally eliminates packet collisions, achieving high performance. Particularly, it reaches high bandwidth utilization even under heavy loads: 90% and 87.5% for the two IR-DCN configurations of 160 and 400 Gbps total capacity, respectively. Also, it achieves low mean end-to-end (e2e) packet delay, lower than 0.25 and 0.12 ms, respectively, providing a reliable solution for time-sensitive DCN traffic. Specifically, simulation results demonstrate that the highest priority traffic experiences e2e delay lower than 1.9 and 1.1 µs, respectively, which is sufficient for the service of the strictest delay requirements of time-sensitive cloud applications. The intra-MAC protocol is decentralized, without the need for a network controller, providing high flexibility. Our IR-DCN proposal is studied in comparison to other currently dominant intra-rack/cluster DCNs, and it achieves from 6% to 57% higher throughput and from 20% to 99% lower e2e delay at high loads. Comparatively, it is on average 80% and 68% more energy and cost efficient, respectively.

HAS-MAC: A Hybrid Asynchronous and Synchronous Communication System for Energy-Harvesting Wireless Sensor Networks

In Energy-Harvesting Wireless Sensor Networks (EH-WSNs), sensors have to continuously adapt their duty cycle to regulate energy consumption according to available energy. Therefore, it is unpractical to preserve an invariable working-schedule for a sensor and relay on a fixed routing path for a long time. For achieving packets forwarding effectively with low transmission latency, asynchronous and synchronous Medium Access Control (MAC) protocols are adopted widely regulating energy consumption in EH-WSNs. Since they bear a clear set of advantages and disadvantages, we propose a communication scheme that hybridizes asynchronous and synchronous MAC protocols for reducing average End-to-End delay in EH-WSNs, where a sensor will switch between the asynchronous and synchronous systems according to its energy supplement and practical scenario for adapting to its duty cycle. Our algorithm is suitable for not only low traffic load, but also high/periodic traffic situation. Especially, when working-schedules of sensors are adjusted dynamically depending on the energy environment, our algorithm provides better performance in EH-WSNs. Through extensive simulation and experiments, we demonstrate that our algorithm is efficient in reducing data transmission latency in EH-WSNs.

A synchronous duty-cycled reservation based MAC protocol for underwater wireless sensor networks

To design an energy-efficient Medium Access Control (MAC) protocol for the Underwater Wireless Sensor Networks (UWSNs) is an urgent research issue since depleted batteries cannot be recharged or replaced in the underwater environment. Moreover, the underwater acoustic channels are affected by hindrances such as long propagation delay and limited bandwidth, which appear in the design of the MAC protocol for the UWSNs. The available MAC protocols for the terrestrial wireless sensor networks exhibit low performance in energy efficiency, throughput and reliability in the UWSNs, and cannot be used in the UWSNs directly because of their unique characteristics. This paper proposes a synchronous duty-cycled reservation-based MAC protocol named Ordered Contention MAC (OCMAC) protocol. The basic mechanism of this protocol is to schedule data transmission by transmitters through the scheduling of Ready To Send (RTS) frames. The protocol eliminates the possible collision during data transmission and improves communication efficiency. The paper analyzes the performance in energy efficiency, throughput and reliability of the protocol by modeling the queuing behavior of OCMAC with a Markov Chain process. Furthermore, the analytical model is validated through a simulation study. The analysis results demonstrated that while providing good throughput and reliability, OCMAC can achieve energy saving.

Beacon Optimization for Optimized Routing Model using Tsch Network

TSCH (Time-Slotted Channel Hopping) protocol is introduced recently by IETF 6TiSCH working group for achieving low energy consumption and highly reliable IEEE 802.15.4e. TSCH is a synchronous MAC (Medium Access Control) protocol with IPv6 enabling Internet of Things (Io T) that are deployed in environments that are prone to interference. However, the IEEE 802.15.4e only describes TSCH link-layer design without a study of communication scheduling and network formation for high density and rapid mobile ad hoc network (MANET) which are still an open issue to the research community. The exiting model incurs high latency and energy overhead for performing device association. To address aforementioned issues, this paper present an Adaptive Routing (AR) model for MANET using mobility enabled TSCH network. Our model reduces the overhead of mobile device within mobility enabled TSCH network by introducing a novel modified beaconing for achieving Adaptive Routing design. Experiment are conducted to evaluate performance of AR over existing approaches shows significant reduction of energy overhead and attain good packet routing outcomes.

Energy Efficient Mobility Aware Clustering Hybrid MAC Protocol in WSN

Mobility in Wireless Sensor Networks (WSN) poses many challenges to design Medium Access Control (MAC) protocol. In this paper, Energy efficient clustering Mobility Hybrid MAC (EMH-MAC) protocol is introduces to manage throughput, delay and energy consumption in WSN. EMH-MAC protocol merges the features of synchronous and asynchronous MAC protocols. EMH-MAC works in two stages: Clustering and Data transmission stage. In the clustering stage MMCDD protocol is used for election of Cluster Head (CH). Data transmission stage works in four segments: two-hop neighbor information, intra-semi synchronous, inter-synchronous communication and data transfer. EMH-MAC is evaluated using Network Simulator-3 and performance is compared with BN-MAC. Simulation results show that EMH-MAC performs well in comparison with BN-MAC in terms of throughput, delay and energy consumption by varying number of nodes and speed of nodes.

A Novel Synchronous MAC Protocol for Wireless Sensor Networks with Performance Analysis.

Synchronous medium access control (MAC) protocols are highly essential for wireless sensor networks (WSN) to support transmissions with energy saving, quality services, and throughput in industrial, commercial and healthcare applications. In this paper, a synchronous channel access mechanism is designed, where sensors can reserve the contention free data transmission slots in different available channels. To reduce the delay of data transmission among the nodes in the mesh topology, a linear programming problem (LPP) model is designed to select suitable relay nodes. Moreover, the performance of the proposed MAC is analyzed and our models are validated with simulation and analytical results. The results show that our proposed MAC protocol outperforms the IEEE 802.15.4e MAC mechanism in terms of throughput, reliability, delay, energy, packet drop rate and transmission success rate.

A Joint Routing and MAC Protocol for Transmission Delay Reduction in Many-to-One Communication Paradigm for Wireless Sensor Networks

We propose a joint routing and medium access control (MAC) protocol, named as JRAM, for reducing transmission delays in a many-to-one communication paradigm for wireless sensor networks (WSNs). Due to the wide variety of WSN applications, there is a need for protocol solutions optimized for specific application classes. JRAM is proposed for WSNs deployed for monitoring multiple events in the same geographic region which require prompt detection and response. In existing contention-based synchronous MAC protocols designed for this, a node gets only one chance to succeed in data transmission scheduling per cycle, and a sink can also only receive data packets from at most one node in a cycle. Therefore, endto-end transmission delay (E2ETD) and packet delivery ratio (PDR) of these protocols drastically degrade with the increase in event occurrence rate (EOR). In contrast, JRAM proposes a novel approach to provide k (k > 1) chances to a node to succeed in data transmission scheduling in a cycle, and also allows a sink to receive data packets from k nodes in the same cycle. This is done, in JRAM, by partitioning the network nodes into k disjoint sets and then using a novel cycle structure. We evaluate JRAM through extensive NS-2.35 simulations and compare its performance with existing pipelined data collection (PDC), adaptive data collection (ADC), and CROPMAC protocols, for different types of traffic loads and traffic patterns. Results suggest that in case of high EOR, JRAM outperforms PDC, ADC and CROPMAC both in terms of the E2ETD and the PDR.

PRIN: A Priority-Based Energy Efficient MAC Protocol for Wireless Sensor Networks Varying the Sample Inter-Arrival Time

Wireless sensor networks (WSNs) are used in a variety of applications to sense and transfer information to the centralized node with energy efficiency increasing the network's lifespan. Other factors, such as quality of service (QoS) is also important to improve the performance of the WSNs, by increasing throughput and reducing end-to-end delay. In this paper, we evaluate the importance of QoS in the Medium Access Control (MAC) protocol for WSNs using different metrics and parameters such as energy efficiency, throughput, delay, and the network lifespan. We propose a new QoS MAC protocol, "PRIority in Node" (PRIN), using static priority in the source and the intermediate node and priority among the node which is one hop from the sink node to achieve QoS in WSNs. Simulation results are compared with those of the synchronous MAC protocol in terms of QoS parameters to show the improved performance of the proposed MAC protocol.

SR-MAC: A Low Latency MAC Protocol for Multi-Packet Transmissions in Wireless Sensor Networks

Event detection is one of the major applications of wireless sensor networks (WSNs). Most of existing medium access control (MAC) protocols are mainly optimized for the situation under which an event only generates one packet on a single sensor node. When an event generates multiple packets on a single node, the performance of these MAC protocols degrades rapidly. In this paper, we present a new synchronous duty-cycle MAC protocol called SR-MAC for the event detection applications in which multiple packets are generated on a single node. SR-MAC introduces a new scheduling mechanism that reserves few time slots during the SLEEP period for the nodes to transmit multiple packets. By this approach, SR-MAC can schedule multiple packets generated by an event on a single node to be forwarded over multiple hops in one operational cycle without collision. We use event delivery latency (EDL) and event delivery ratio (EDR) to measure the event detection capability of the SR-MAC protocol. Through detailed ns-2 simulation, the results show that SR-MAC can achieve lower EDL, higher EDR and higher network throughput with guaranteed energy efficiency compared with R-MAC, DW-MAC and PR-MAC.

A Traffic-Aware Energy Efficient Scheme for WSN Employing an Adaptable Wakeup Period

Recently, Wireless Sensor Networks (WSN) have come to require an energy efficiency and a guaranteed delivery delay time, on the contrary to traditional Medium Access Control (MAC) protocols that have mostly aimed for a high throughput. In order to satisfy these new significant requirements, many of the newer WSN MAC protocols employ duty cycled mechanism, in order to improve energy efficient techniques in the MAC layer. This duty cycled mechanism is oriented to the toggling of the transceiver's conditions composed of the wakeup and sleep states. However, regrettably, the channel conditions of a wireless network can be changed anytime according to the traffic congestion. If a high congestion is present, an insufficient wakeup period can cause the successful communication ratio to worsen. This can be a weakness in previous duty cycled mechanisms due to their lack of consideration for the network conditions. Therefore, we have devised and designed an efficient new scheme, the adaptable wakeup period, which can resolve this issue. We present analyses and the simulated results of our work, together with a comparison between the synchronous and asynchronous MAC protocols, using two types of analysis models that we suggest.

Performance Evaluation of Synchronous Energy Efficient MAC Protocols for Wireless Sensor Networks

Energy efficient medium access control (MAC) protocol designs for wireless sensor networks (WSNs) have already generated interests among researches due to ever increasing range of applications of WSNs. Nodes in a WSN typically operate unattended with a limited power source, energy efficient operations of the sensor nodes especially at the MAC level is very important because majority of energy expenditure take place at the radio level. MAC protocols in WSNs for diverse applications with different objectives have been proposed by researchers. In this paper, we investigate three energy-efficient synchronous MAC protocols for WSNs emphasizing their strength and weakness. Our analysis as well as simulation studies reveal the suitability of these protocols in deployed sensor fields. As a result of our investigation, we found out some open research issues in energy-efficient MAC layer design which we highlighted toward the end of this paper.