IW-MAC: a invite and wait MAC protocol for power efficient wireless sensor networks

Energy efficiency of the MAC protocol is a key design factor for wireless sensor networks (WSNs). Due to the importance of the problem, a number of energy efficient MAC protocols have been developed for WSNs. Preamble-sampling based MAC protocols (e.g., B-MAC and X-MAC) have overheads due to their preambles, and are inefficient at large wakeup intervals. SCP-MAC, a very energy efficient scheduling MAC protocol, minimizes the preamble by combining preamble sampling and scheduling techniques; however, it does not prevent energy loss due to overhearing; in addition, due to its synchronization procedure, it results in increased contention and delay. In this paper, we present an energy efficient MAC protocol for WSNs that avoids overhearing and reduces contention and delay by asynchronously scheduling the wakeup time of neighboring nodes. To validate our design and analysis, we implement the proposed scheme on the MicaZ platform. Experimental results show that AS-MAC considerably reduces energy consumption, packet loss and delay when compared with SCP-MAC.

In monitoring wireless sensor networks (WSNs) with event-driven applications, the generated traffic usually has bursty characteristics when an event occurs. Transient congestion in the networks would increase delay and packet loss rate severely, reducing the network performance greatly. Through the analysis on delay and packet loss rate in congestion, this paper proposes a congestion-aware mac protocol (C-MAC) for wireless sensor networks. In C-MAC, backoff delay of the nodes around contention area is adopted as a congestion indication. In normal state, the CSMA/CA is working well at sensor nodes. And when the congestion occurs, localized TDMA replaces the CSMA/CA in the congestion nodes. With the above mechanism, the congestion nodes only deliver their data during its assigned slots to control the contention overhead. Finally, we implement the C-MAC in our sensor network testbed. The experiment results show that the proposed MAC protocol could effectively operate on the congestion caused by burst information, and reduce both the delay and packet loss rate significantly.

The problem of idle listening is one of the most significant sources of energy consumption in wireless sensor nodes. Many techniques have been proposed based on duty cycling to reduce this idle listening. This paper presents Adaptive Scheduling Predictive-Wakeup MAC (AS-PW-MAC), a new MAC protocol based on asynchronous duty cycling. AS-PW-MAC introduces RTE and RAS messages for pending data transmission. RTE and RAS are beneficial for varying traffic loads. We evaluate the performance of AS-PW-MAC through detailed ns-2 simulation and compare it to RI-MAC and PW-MAC, two well-known MAC protocols. Our evaluation includes clique, grid and random network scenarios. In all experiments, AS-PW-MAC significantly out performs RI-MAC and PW-MAC protocols. AS-PW-MAC achieves higher packet delivery ratio under a wide range of traffic loads compared to RI-MAC and PW-MAC. Especially, when there are contending flows, such as bursty traffic or transmissions from hidden nodes, AS-PW-MAC significantly improves the packet delivery ratio and delivery latency. The delivery latency for AS-PW-MAC is less than 21% compared to RI-MAC and PW-MAC. In all experiments, AS-PW-MAC maintained approximately 100% packet delivery ratio.

In this paper, we propose a light-weight and adaptive scheduling-based media access control protocol (LASMAC) for wireless sensor networks. Our primary goal is to achieve an energy-efficient and traffic-adaptive TDMA-based MAC protocol with low-overhead slot reservation. In our protocol, each node dynamically and flexibly assigns slots by exchanging information on the number of slots it wants to send within neighbors by contention-based access. The overhead of control packets in slot reservation is reduced. In addition, the duration of active period in random access for slot reservation is dynamically changed based on the traffic. Performance evaluation by simulation shows that our proposed MAC protocol is more energy-efficient than previous methods keeping throughput under hotspot traffic

Directional antennas have been extensively used in designing MAC protocols for wireless ad hoc networks in recent years. Directional antennas provide many advantages over the classical antennas which are omnidirectional. These advantages include spatial reuse and increase in coverage range. One of the main considerations in designing MAC protocols for static wireless networks is to reduce power consumption at the sensor nodes. This is usually done by imposing transmission and receiving schedules on the sensor nodes. Since it is desirable for a sensor network to be self managed, these schedules need to be worked out by individual nodes in a distributed fashion. In this paper, we show that directional antennas can be used effectively to design an energy efficient MAC protocol for wireless sensor networks. Our MAC protocol conserves energy at the nodes by calculating a scheduling strategy at individual nodes and by avoiding packet collisions almost completely.KeywordsSensor NetworkSensor NodeWireless Sensor NetworkTime SlotPacket Delivery RatioThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Performance analysis of an adaptive, energy-efficient MAC protocol for wireless sensor networks

The efficient use of energy is an important performance metric to extend the lifetime of wireless sensor networks. Since major energy consumption of node is due to its transceiver, the design of MAC protocol plays a vital role in sensor network design. In cluster based sensor networks, due to the different functions of member node and cluster head node, the usage of common MAC protocol results increased energy consumption. To overcome this problem, a novel energy efficient hybrid MAC protocol (EEHMAC) for cluster based wireless sensor networks is proposed in this paper. The proposed EEHMAC protocol uses E-TDMA (Energy efficient TDMA) for intra-cluster communication and FDMA (Frequency Division Multiple Access) for inter-cluster communication. IDS (Iterative Deepening Search) based Scheduling algorithm is used for assigning time slot and frequency slot to nodes. Nodes in EEHMAC follow the periodic duty cycle, which reduces the idle listening, and overhearing problems. Simulation results reveal that an average of 18% energy saving is achieved compared to LEACH (Low Energy Adaptive Clustered Hierarchy) protocol and 10% energy is saved in comparison with GH-MAC (Graph theory based Hybrid MAC) protocol. It is evident that delay of EEHMAC is reduced by 17% and throughput is increased by 15% under all traffic conditions. These results demonstrate that EEHMAC performs better than existing MAC protocols in terms of energy efficiency, delay and throughput.

In wireless sensor networks (WSNs), most energy saving asynchronous MAC protocols are custom tailored for unicast communications only.However, broadcast protocols are very commonly used in WSNs for a variety of functionalities, such as gathering network topology information, event monitoring and query processing.In this paper, we propose a novel low-power asynchronous broadcast MAC protocol called Alarm Broadcast (A-CAST).A-CAST employs the strobe preamble that specifies the residual waiting time for the following data transmission.Each receiver goes back to sleep upon hearing the strobe preamble for the residual time duration, to conserve energy and to wake up just before data transmission starts.We compute the energy consumption of A-CAST via rigorous mathematical analysis.The analytic results show that A-CAST outperforms B-CAST, a simple broadcast extension of the well-known B-MAC.We also implement A-CAST on sensor motes and evaluated its performance through real experiments.Our experimental results show that A-CAST reduces the energy consumption by up to 222% compared to the previously proposed protocols.

The unique nature of wireless sensor networks (WSNs) poses new design challenges for development of applications, protocols and algorithms. In recent years, a substantial amount of research effort has been directed towards overcoming the underlying challenges to minimize energy consumption by the sensor nodes. The exchange of routing control packets has a significant impact on energy consumption from the small irreplaceable and non rechargeable batteries of the sensor nodes. In this paper, we propose a cross-layer adaptive routing (CLAR) protocol for WSNs, which aims to minimize the use of routing control packets in WSNs; thereby minimizing energy consumption which in turn prolongs network-lifetime. We also develop analytical model to derive energy consumption for route establishment and present simulation results, which reveal better performance and improved energy efficiency in WSNs when using the proposed cross-layer adaptive routing protocol.

In wireless sensor networks, MAC protocol is used to achieve efficient, fair and balanced allocation of wireless channel resources and access control of nodes in the network, and to control the communication process of nodes in the network. The energy consumption of wireless sensor nodes is mainly concentrated in the communication unit, including: data transceiver, idle listening, protocol control overhead, etc. A good MAC protocol is beneficial to reduce unnecessary energy consumption and enhance node life time. At the same time, MAC protocol, as the bottom protocol of wireless sensor network, provides a stable and reliable communication foundation for the realization of the upper protocol. Therefore, a large number of scholars at home and abroad have carried out extensive and in-depth research on MAC layer protocol of network. In this paper, the research process and progress of MAC layer protocol in wireless sensor networks are analyzed, and the research progress of MAC layer protocol in multi-radio frequency and multi-channel wireless sensor networks is analyzed.

MAC protocols for Wireless Sensor Networks based on channel checking to detect incoming packets (such as Low Power Listening, LPL) require some form of synchronization among sensors, in order to schedule the times in which the sender and the receiver should turn on their radios, and to ensure correct packet delivery. However, while travelling along multihop paths, packets may accumulate delays that force the sensors either to incur packet losses and retransmissions or to readjust the planned scheduling. In both cases this fact impacts on the energy budget of the sensors. In this paper we propose a cross-layer optimization for MAC protocols that use LPL. This optimization takes into account high-level information of the application in order to compute adaptive delays in every sensor along a multihop path, with the goal of adjusting precisely the activity time window of the sensor along the path. We validate our delay-based model by evaluating different scenarios, and we compare it against the LPL model. The simulation results confirm the validity of our approach and demonstrate that a delay-based model can improve the synchronization achieved through the LPL strategy.

Naturopathic approaches to weight loss in clinical practice – a mixed methods study

The efficient use of energy in wireless sensor networks is critical issue as the battery of a sensor node, in most cases, cannot be recharged or replaced after deployment. In order to detect an event, a sensor node spends most of the time in monitoring its environment, during which a significant amount of energy can be saved by placing the radio in the low power sleep mode when no reception and/or transmission of data is involved. In this paper, we discuss the design of a new MAC protocol for wireless sensor networks whose goal is to extend the lifetime of the network by avoiding major energy waste causes, such as collisions, overhearing and idle listening, without compromising other network performance measures such as network throughput. The performance of the protocol is studied by simulation and is compared to that of the well known S-MAC protocol which is designed to save energy and to the IEEE 802.11 protocol which is designed to maximize throughput.

We propose a pseudo-random asynchronous duty cycle MAC protocol in wireless sensor networks. The proposed protocol adopts a hash function to determine the next wake-up times. As the next wake-up times are known in advance, the sensor nodes do not need to remain active until their intended receivers wake up. Given an end-to-end delay requirement, the proposed protocol significantly decreases energy consumption by reducing the idle listening time.

Wireless Sensor Networks use battery-operated computing and sensing devices. It is often impractical or even impossible to charge/replace the exhausted batteries of the nodes. Thus, energy consumption is the main concern in a wireless sensor network. Moreover, a critical event detected by the sensor network should be delivered to the user as soon as possible. Thus, for sensor networks, both energy efficiency and transmission latency are important parameters. In this paper, we propose a novel asynchronous, duty cycled, energy efficient, and low transmission delay for wireless sensor networks, which addresses all the sources of energy waste to make the medium access more energy efficient, while keeping transmission delay low.The currently available asynchronous contention-based MAC protocols require that proper strategies for sender and receiver nodes are provided to rendezvous. However, the proposed protocol does not rely on any rendezvous between sender and receiver. For evaluating the novel MAC protocol, we have simulated this protocol and two very efficient and established MAC protocols, RTS/CTS IEEE 802.11 and S-MAC. The simulation results indicate that the proposed protocol has very good performance. In addition, as the results show, the novel protocol provides a very suitable balance between energy efficiency and transmission delay.