Novel Medium Access Control (MAC) Protocols for Wireless Sensor and Ad Hoc Networks (WSANs) and Vehicular Ad Hoc Networks (VANETs)

Efficient medium access control (MAC) is a key part of any wireless network communication architecture. MAC protocols are needed for nodes to access the shared wireless medium efficiently. Providing high throughput is one of the primary goals of the MAC protocols designed for wireless networks. MAC protocols for Wireless Sensor and Ad hoc networks (WSANs) must also conserve energy as sensor nodes have limited battery power. On the other hand, MAC protocols for Vehicular Ad hoc networks (VANETs) must also adapt to the highly dynamic nature of the network. As communication link failure is very common in VANETs because of the fast movement of vehicles so quick reservation of packet transmission slots by vehicles is important. In this thesis we propose two new distributed MAC algorithms. One is for WSANs and the other one is for VANETs. We demonstrate using simulations that our algorithms outperform the state-of-the-art algorithms

Medium Access Control for Wireless Sensor Networks based on Impulse Radio Ultra Wideband

This paper describes a detailed performance evaluation of distributed Medium Access Control (MAC) protocols for Wireless Sensor Networks based on Impulse Radio Ultra Wideband (IR-UWB) Physical layer (PHY). Two main classes of Medium Access Control protocol have been considered: Slotted and UnSlotted with reliability. The reliability is based on Automatic Repeat ReQuest (ARQ). The performance evaluation is performed using a complete Wireless Sensor Networks (WSN) simulator built on the Global Mobile Information System Simulator (GloMoSim). The optimal operating parameters are first discussed for IR-UWB in terms of slot size, retransmission delay and the number of retransmission, then a comparison between IR-UWB and other transmission techniques in terms of reliability latency and power efficiency

A Study On Protocol Stack In 6lowpan Model

Due to recent advances of heterogeneous network and the emergence of Internet of Things (IoT), wireless personal area networks including wireless sensor networks are assumed to be part of the huge heterogeneous network. This calls for a smooth integration between the higher network layer protocols Internet Protocol version 6 (IPv6) and the lower media access control (MAC) layer protocol IEEE 802.15.4. IEEE 802.15.4 is a standard that specifies the physical layer and MAC layer for Wireless Personal Area Network (WPAN). This standard is suited for Low-Rate Wireless Personal Area Networks (LR-WPANs), a constrained network of tiny, low power, low rate, small size memory with low computation and communication capabilities. However, IPv6 is forming the backbone of the desired heterogeneous network. Direct integration between IPv6 and IEEE 802.15.4 lower network layers is not possible. Hence, latest technology development is the transmission of IPv6 packets over Low-power Wireless Personal Area Networks (6LoWPAN). This has enforced some modification to the existing protocol stack and introduced the 6LoWPAN protocol stack. The 6LoWPAN protocol stack involves 802.15.4 physical (PHY) and Medium Access Control (MAC) layer, 6LoWPAN adaptation layer, network layer, transport layer and application layer with specific 6LoWPAN application. This review paper describes all layers in 6LoWPAN protocol stack including its routing protocols, namely the Route-over and Mesh-under. These routing schemes are applied in 6LoWPAN adaptation layer and network layer

Energy-efficient hybrid system for Wireless Body Area Network Applications

Wireless Body Area Networks (WBANs) consist of a number of miniaturized wearable or implanted sensor nodes that are employed to monitor vital parameters of a patient over long duration of time. These sensors capture physiological data and wirelessly transfer the collected data to a local base station in order to be further processed. Almost all of these body sensors are expected to have low data-rate and to run on a battery. Since recharging or replacing the battery is not a simple task specifically in the case of implanted devices such as pacemakers, extending the lifetime of sensor nodes in WBANs is one of the greatest challenges. To achieve this goal, WBAN systems employ low-power communication transceivers and low duty cycle Medium Access Control (MAC) protocols. Although, currently used MAC protocols are able to reduce the energy consumption of devices for transmission and reception, yet they are still unable to offer an ultimate energy self-sustaining solution for low-power MAC protocols. This paper proposes to utilize energy harvesting technologies in low-power MAC protocols. This novel approach can further reduce energy consumption of devices in WBAN systems

Has time come to switch from duty-cycled MAC protocols to wake-up radio for wireless sensor networks?

Duty-cycled Medium Access Control (MAC) protocols certainly improve the energy efficiency of wireless networks. However, most of these protocols still suffer from severe degrees of overhearing and idle listening. These two issues prevent optimum energy usage, a crucial aspect in energy-constrained wireless networks such as wireless sensor networks (WSNs). Wake-up radio (WuR) systems drastically reduce these problems by completely switching off the nodes' microcontroller unit (MCU) and main radio transceiver until a secondary, extremely low-power receiver is triggered by a particular wireless transmission, the so called wake-up call. Unfortunately, most WuR studies focus on theoretical platforms and/or custom-built simulators. Both these factors reduce the associated usefulness of the obtained results. In this paper, we model and simulate a real, recent, and promising WuR hardware platform developed by the authors. The simulation model uses time and energy consumption values obtained in the laboratory and does not rely on custom-built simulation engines, but rather on the OMNET++ simulator. The performance of the WuR platform is compared to four of the most well-known and widely employed MAC protocols for WSN under three real-world network deployments. The paper demonstrates how the use of our WuR platform presents numerous benefits in several areas, from energy efficiency and latency to packet delivery ratio and applicability, and provides the essential information for serious consideration of switching duty-cycled MAC-based networks to WuR.Peer ReviewedPostprint (author's final draft

Performance evaluation of MAC transmission power control in wireless sensor networks.

In this paper we provide a method to analytically compute the energy saving provided by the use of Transmission Power Control (TPC) at the MAC layer in Wireless Sensor Networks (WSN). We consider a classical TPC mechanism: data packets are transmitted with the minimum required power to achieve a given packet error probability, whereas the additional MAC control packets are transmitted with the nominal (maximum) power. This scheme has been chosen because it does not modify the network topology, since control packet transmission range does not change. This property also allow us to compute analytically the expected energy savings. Besides, this type of TPC can be implemented in the current sensor hardware, and can be applied directly to several MAC protocols already proposed for WSN. The foundation of our analysis is the evaluation of L ratio, defined as the total energy consumed by the network using the original MAC protocol divided by the total energy consumed if the TPC mechanism is employed. In the L computation we emphasize the basic properties of sensor networks. Namely, the savings are calculated for a network that is active a very long time, and where the number of sensors is supposed to be very large. The nodes position is assumed to be random -for the sake of example a normal bivariate distribution is assumed in the paper- and no node mobility is considered. In the analysis we stress the radio propagation and the distribution of the nodes in the network, that will ultimately determine the performance of the TPC. Under these conditions we compute the mean value of L. Finally, we have applied the method to evaluate the benefits of TPC for TDMA and CSMA with two representative protocols, L-MAC and S-MAC using their implementation reference parameters. The conclusion is that, while S-MAC does not achieve a significant improvement, LMAC may reach energy savings up to 10-20%

Fixed chain-based wireless sensor network for intelligent transportation systems

Wireless Sensor Networks (WSNs) are distributed and interconnected wirelessly sensors that are used in a variety of fields of our daily life, such as the manufacturing, utility operations and traffic monitoring. Many WSN applications come with some technical weaknesses and issues, especially when they are used in Intelligent Transportation Systems (ITS). For ITS applications that use a fixed chain topology which contains road studs deployed at ground level, there are some challenges related to radio propagation, energy constraints and the Media Access Control (MAC) protocol. This thesis develops a ground level radio propagation model for communication between road studs, and energy efficiency metrics to manage the resources to overcome the energy constraints, as well as a MAC protocol compatible with chain topology and ground level communication. For the challenges of the physical layer, this thesis investigates the use of a WSN for communicating between road-based nodes. These nodes are situated at ground level, and two-way wireless communication is required between the nodes and from the nodes to a roadside control unit. Field measurements have been carried out to examine the propagation close to the ground to determine the maximum distance between road-based nodes as a function of the antenna height. The results show that for a frequency of 2.4 GHz, a range of up to 8m is achievable with 2mW equivalent isotropically radiated power (EIRP). An empirical near-ground level radio propagation model has been derived, and the predicted results from this model are shown to match closely to the measured results. Since wireless sensor networks have power constraints, green energy efficiency metrics have been proposed for low-power wireless sensors operating at ground level. A numerical analysis is carried out to investigate the utilisation of the green energy efficiency metrics for ground level communication in wireless sensor networks. The proposed metrics have been developed to calculate the optimal sensor deployment, antenna height and energy efficiency level for the near ground wireless sensor. As an application of the proposed metrics, the relationship between the energy efficiency and the spacing between the wireless sensor nodes has been studied. The results provide guidance for energy efficient deployment of near ground level wireless sensors. To manage the communication between large numbers of nodes deployed on a chain topology, this research presents a time division multiple access (TDMA) MAC protocol that is specifically designed for applications requiring periodic sensing of the sensor field. Numerical analysis has been conducted to investigate the optimum transmission scheduling based on the signal-to-interference-plus-noise-ratio (SINR) for ground level propagation model applied on wireless chain topology. The optimised transmission schedule considers the SINR value to enable simultaneous transmission from multiple nodes. The most significant advantages of this approach are reduced delay and improved Packet Received Ratio (PRR). Simulation is performed to evaluate the proposed protocol for intelligent transport system applications. The simulation results validate the MAC protocol for a fixed chain topology compared with similar protocols

A Collision Avoidance Based Energy Efficient Medium Access Control Protocol for Clustered Underwater Wireless Sensor Networks

Underwater Wireless Sensor Networks (UWSNs) are typically deployed in energy constrained environments where recharging energy sources and replacing batteries are not viable. This makes energy efficiency in UWSNs a crucial directive to be followed during Medium Access Control (MAC) design. Multiplexing and scheduling based protocols are not ideal for UWSNs because of their strict synchronization requirements, longer latencies and constrained bandwidth.This paper presents the development and simulation analysis of a novel cross-layer communication based MAC protocol called Energy Efficient Collision Avoidance (EECA) MAC protocol. EECA-MAC protocol works on the principle of adaptive power control, controlling the transmission power based on the signal strength at the receiver. EECA-MAC enhances the conventional 4-way handshake to reduce carrier sensing by implementing an enhanced Request to Send (RTS) and Clear to Send (CTS) handshake and an improved back-off algorithm.Simulation analysis shows that the measures taken to achieve energy efficiency have a direct effect on the number of packet retransmissions. Compared to the Medium Access with Collision Avoidance (MACA) protocol, EECA-MAC shows a 40% reduction in the number of packets that are delivered after retransmissions. This reduction, coupled with the reduced signal interference, results in a 16% drop in the energy utilized by the nodes for data transmission

Adaptive Duty Cycling MAC Protocols Using Closed-Loop Control for Wireless Sensor Networks

The fundamental design goal of wireless sensor MAC protocols is to minimize unnecessary power consumption of the sensor nodes, because of its stringent resource constraints and ultra-power limitation. In existing MAC protocols in wireless sensor networks (WSNs), duty cycling, in which each node periodically cycles between the active and sleep states, has been introduced to reduce unnecessary energy consumption. Existing MAC schemes, however, use a fixed duty cycling regardless of multi-hop communication and traffic fluctuations. On the other hand, there is a tradeoff between energy efficiency and delay caused by duty cycling mechanism in multi-hop communication and existing MAC approaches only tend to improve energy efficiency with sacrificing data delivery delay. In this paper, we propose two different MAC schemes (ADS-MAC and ELA-MAC) using closed-loop control in order to achieve both energy savings and minimal delay in wireless sensor networks. The two proposed MAC schemes, which are synchronous and asynchronous approaches, respectively, utilize an adaptive timer and a successive preload frame with closed-loop control for adaptive duty cycling. As a result, the analysis and the simulation results show that our schemes outperform existing schemes in terms of energy efficiency and delivery delay