Use of aerial platforms for energy efficient medium access control in wireless sensor networks

Wireless Sensor Networks (WSNs) have been widely recognized as a promising solution for enhancing various aspects of electric power grid and realizing the vision of smart grid. However, energy crisis and challenging wireless environment in smart grid create a number of challenges for WSNs, as a result of which energy efficiency become critically important. On the other hand, cognitive radio (CR) technology is expected to play a vital role in smart grid networks. Cognitive Sensor Networks (CSNs) can effectively address some unique challenges of WSNs in smart grid. In this paper, we aim to design an energy efficient Medium Access Control (MAC) protocol for CSNs. In this regard, we propose ECR-MAC, which is an energy-efficient receiver-based MAC protocol for CSNs. ECR-MAC uses a energy-efficiency based auction mechanism and preamble sampling techniques for providing high energy efficiency and reliability. In addition, ECR-MAC explicitly accounts for the peculiarities of a CR environment. Analytical and simulation results demonstrate the effectiveness of ECR-MAC as a viable solution for CSNs.

Design of energy efficient medium access control (MAC) protocol for wireless sensor network (WSN) containing mobile nodes is a challenging task. Majority of the MAC protocols for wireless sensor networks assume static sensor nodes, which results in poor performance of such protocols in a network containing mobile nodes. In this paper we propose a MAC protocol which is energy efficient as well as suitable for a WSN containing mobile nodes. The proposed protocol is based on both TDMA and CSMA. It adjusts the frame size to adapt to the changes in mobility and traffic conditions. The performance of the proposed protocol has been compared with LEACH-C protocol. It outperforms LEACH-C in terms of average energy consumption, packet delivery ratio and network life time.

Wireless sensor networks (WSNs) are one of the very active research area. They have many applications like military, health care, environmental monitoring and industrial monitoring. The sensor nodes have limited energy source. Since in many cases the nodes are deployed in unreachable areas, hence recharging or replacing the battery of the sensor nodes is not an option. Therefore, one must employ techniques to conserve the energy by reducing the energy consumption by the nodes. In this paper, we discuss about the different energy saving schemes investigated by different research community in WSNs to reduce the energy consumption of the nodes and thereby improving the lifetime of the overall network. Energy saving protocols such as duty cycle, energy efficient routing, energy efficient medium access control (MAC), data aggregation, cross layer design and error control code (ECC) are discussed. Sleep/wake up method is adopted by the duty cycle approach to reduce the active time of the nodes and conserve their energy. The routing and MAC protocols use suitable energy efficient algorithms for saving energy. The data aggregation aims to save energy by reducing the number of transmissions. On the other side, cross layer approach looks for a cross layer optimization solution to improve the energy efficiency of the network. ECC reduces energy consumption by virtue of coding gain it offers which allows lower signal-to-noise ratio (SNR) to achieve the same bit error rate (BER) as an uncoded system. Some techniques such as use of directional antennas, topology control and transmission power control which have been widely investigated for other ad-hoc networks for energy conservation are also discussed in brief in this paper.

Multimedia applications require significantly higher bandwidth than conventional textual applications. Furthermore, multimedia stream requires time sensitive and involves high‐energy consumption, which become more challenging on resource constrained networks such as wireless multimedia sensor network (WMSN). As a result, developing an energy efficient algorithm to prolong the network lifetime is the main reoccurring issue in WMSN. Although the duty cycling mechanism has been proven to be an efficient solution for energy saving in various WSN applications, the tradeoff between energy efficiency and quality of service (QoS) on WMSN remains striking. In this article, an adaptive dynamic duty cycle mechanism for energy‐efficient medium access control (ADE‐MAC) is proposed for WMSNs. ADE‐MAC uses a unique asynchronous duty cycle approach to schedule the sleep pattern of each sensor node which can be adapted according to the incoming traffic rate and queuing delay at each node. In the proposed system, the overhead of synchronization is avoided because every node has its own scheduling sleep, and the only sender node must wake up the receiver nodes by using preambles packets. The findings that result from comprehensive simulation show that ADE‐MAC outperforms the baseline approaches in term of delivery ratio by 12%, less packet overhead by 28%, less end‐to‐end delay by 19%, and less power consumption by 41% compared to the baseline mechanisms.

Directional antennas have numerous advantages over traditional omnidirectional antennas, which include more spatial reuse, extended range, less interference, and less energy consumption. Directional antennas introduce deafness and new hidden terminal problems. Deafness may cause more collisions, and hidden terminal problems may result in more retransmissions, poor quality of service, more energy consumption, and less packet delivery ratio. Hence, it is important to design of an effective medium access protocol specifically for directional antennas in order to reap the benefits of directional antennas while managing deafness and hidden terminal problems, otherwise the challenges can adversely affect system performance. In wireless sensor networks, the sensors are battery powered with limited supply of energy. Therefore, energy efficient protocols and solutions are immensely important with the desired goal of extending the network lifetime longer than what is possible through the omnidirectional antennas. In this thesis, I have proposed an energy efficient scheduled directional medium access control protocol (DTRAMA) which is specially designed for the wireless sensor nodes which use directional antennas in wireless sensor networks. It is a traffic adaptive scheduled medium access protocol in which nodes create their transmission and sleep schedules on the basis of their traffic. Scheduled medium access for packet transmission is used to address the deafness and hidden terminal problems caused by the use of directional communication in contention based MAC protocols. Use of directional antenna reduces interference which indirectly improves packet delivery ratio by improving the signal to noise ratio and by reducing the packet error rate. DTRAMA is energy efficient: firstly because the nodes use directional data communication which requires lower node transmit power than the omnidirectional data communication for the same transmission range; and secondly, because the nodes schedule their sleep period to reduce idle listening and overhearing which improves energy efficiency. In DTRAMA, sleep schedule of the node is traffic adaptive which is essential to maximize the sleep period. The node, by using spatial reuse checks, reuses the wireless medium to the maximum extent to reap the spatial reuse benefits of the directional antenna. The nodes reduce their packet latency through spatial reuse. Through simulation and by using different topologies, I have compared the performance of DTRAMA with those of omnidirectional schedule MAC protocol (TRAMA) and contention based directional MAC protocol (DMAC), which clearly shows that DTRAMA outperforms TRAMA and DMAC in packet delivery ratio and outperforms TRAMA in terms of packet latency.

Directional antennas have numerous advantages over traditional omnidirectional antennas, which include more spatial reuse, extended range, less interference, and less energy consumption. Directional antennas introduce deafness and new hidden terminal problems. Deafness may cause more collisions, and hidden terminal problems may result in more retransmissions, poor quality of service, more energy consumption, and less packet delivery ratio. Hence, it is important to design of an effective medium access protocol specifically for directional antennas in order to reap the benefits of directional antennas while managing deafness and hidden terminal problems, otherwise the challenges can adversely affect system performance. In wireless sensor networks, the sensors are battery powered with limited supply of energy. Therefore, energy efficient protocols and solutions are immensely important with the desired goal of extending the network lifetime longer than what is possible through the omnidirectional antennas. In this thesis, I have proposed an energy efficient scheduled directional medium access control protocol (DTRAMA) which is specially designed for the wireless sensor nodes which use directional antennas in wireless sensor networks. It is a traffic adaptive scheduled medium access protocol in which nodes create their transmission and sleep schedules on the basis of their traffic. Scheduled medium access for packet transmission is used to address the deafness and hidden terminal problems caused by the use of directional communication in contention based MAC protocols. Use of directional antenna reduces interference which indirectly improves packet delivery ratio by improving the signal to noise ratio and by reducing the packet error rate. DTRAMA is energy efficient: firstly because the nodes use directional data communication which requires lower node transmit power than the omnidirectional data communication for the same transmission range; and secondly, because the nodes schedule their sleep period to reduce idle listening and overhearing which improves energy efficiency. In DTRAMA, sleep schedule of the node is traffic adaptive which is essential to maximize the sleep period. The node, by using spatial reuse checks, reuses the wireless medium to the maximum extent to reap the spatial reuse benefits of the directional antenna. The nodes reduce their packet latency through spatial reuse. Through simulation and by using different topologies, I have compared the performance of DTRAMA with those of omnidirectional schedule MAC protocol (TRAMA) and contention based directional MAC protocol (DMAC), which clearly shows that DTRAMA outperforms TRAMA and DMAC in packet delivery ratio and outperforms TRAMA in terms of packet latency.

Energy efficiency is of utmost importance for wireless sensor networks deployed without any possibility of battery replenishments. Thus, design of energy efficient algorithms and protocols must consider resource constraints while maintaining the desired level of QoS. In this paper, we present EE-MAC, an Energy Efficient medium access control (MAC) protocol for distributed wireless sensor networks. EE-MAC achieves a low-duty-cycle and hence low energy consumption through optimized sleep intervals while transitioning between sleep and active states. We consider a weighted linear combination of delay and energy saving as the performance metrics and through extensive simulations, we observe reduced energy consumption at the cost of increased delay. EE-MAC also improves the delay performance for fixed number of nodes compared to S-MAC.

Energy efficiency is one of the important critical metrics during protocol design in Wireless Sensor Networks (WSNs). Existing Medium Access Control (MAC) protocols do not take the initial node power into consideration, which may result in unfair power consumption, especially for low-power nodes. This paper presents an energy-efficient dual-layer MAC protocol with adaptive layer duration for WSNs. The suggested MAC protocol aims to minimize the energy consumption for low-power nodes. Performance evaluation is conducted to compare the proposed MAC protocol with both Sensor-MAC (S-MAC) and Multi-Layer MAC (ML-MAC) using computer simulations. The simulation results show that the proposed MAC protocol saves energy more than both S-MAC and ML-MAC. The proposed protocol saves 66.2% and 34.1% of the energy compared to S-MAC and ML-MAC, respectively.

In this paper we propose a simple relay enabled medium access (SRMAC) protocol that enables cooperative relay transmissions. Due to the wireless signal power attenuation with distance, using a relay in a wireless network can make wireless networking more bandwidth efficient at the expense of requiring multiple transmissions for a single packet. Standard MAC protocols such as the IEEE 802.11 MAC protocol, while useable with relaying, however are not designed explicitly for relay communication. When IEEE 802.11 MAC protocol is used for cooperative communication such a relaying, each packet transmission would need to separately contend for the channel via a channel access procedure which can use significant resources (both energy and bandwidth). Because using a single relay requires two transmissions, an efficient medium access control (MAC) protocol that supports two hop transmission is needed. We introduce a protocol, SRMAC, which is a simple cooperative MAC protocol that utilizes information from the physical layer for the MAC operation of relay networks. We consider the bandwidth efficiency of SRMAC protocol considering both the physical layer and MAC layer. The SRMAC protocol includes the possibility of both cooperative transmission and direct transmission. With SRMAC, cooperative transmission (relaying) can be dynamically chosen when it is more beneficial than direct transmission. The SRMAC protocol can improve the throughput by up to 20% compared to conventional MAC protocols.

Two important criteria of wireless body area networks (WBANs) are low power consumption and delay. These criteria can be met by designing efficient medium access control (MAC) protocols. In this paper, two TDMA-based MAC protocols are proposed. The first protocol, TM–MAC makes use of only a main radio. The second proposed protocol, TWM–MAC makes use of a WUR alongside the main radio. The two proposed protocols are compared with different categories of standard MAC protocols and it is shown that they outperform the standard ones by improving the power consumption and delay. The TWM–MAC consumes 55% less power consumption than the Scheduled Channel Polling MAC (SCP–MAC) protocol for a high traffic scenario on the high-rate platform while the TM-MAC consumes 85% less power consumption than the SCP–MAC. For a low traffic scenario, the TWM–MAC performs 53.5% better than the SCP–MAC protocol and 77.5% better than the very low power MAC (VLPM) protocol on the high and low-rate platforms respectively. An improvement in delay was observed with the TWM–MAC protocol for high traffic situations. The TWM–MAC protocol surpasses the VLPM protocol by 81.1% in terms of latency for a high traffic scenario and 3.2% for a low traffic scenario.

Medium Access Control (MAC) protocol is one of the key network protocols that ensure Wireless Sensor Networks (WSNs) maintain high performance during communication. MAC protocol design plays an important role in improving the performances of the whole network. First, Wireless Passive Sensor Networks (WPSNs) and MAC protocols are introduced in this paper. Second, some existing MAC protocols are introduced. Sensor MAC (S-MAC) protocol is analyzed and existing improved backoff algorithms are introduced. A new MAC protocol called Improved Sensor MAC (IS-MAC) is then proposed to solve the problem that the contention window (CW) during carrier sense is fixed in S-MAC protocol. IS-MAC protocol is able to adjust CW in terms of network load, so energy consumption can be decreased. Finally, according to the simulation results on NS2, the proposed protocol has better performance in terms of throughput and energy consumption.

The properties of underwater acoustic channel are quite different from those of terrestrial wireless sensor networks, which brings many challenges to design an efficient media access control (MAC) protocol for underwater acoustic sensor networks (UWASNs). In order to overcome the long propagation delay and the funneling effect of UWASNs, a MAC protocol, named path-oriented code assignment (POCA) CDMA MAC (POCA-CDMA-MAC) protocol, is proposed in the paper. In the proposed protocol, a round-robin method and the CDMA technology are used to make the sink receive packets from multiple neighbors at the same time. Unlike other CDMA-based protocols using the transmitter-oriented code assignment (TOCA) or the receiver-oriented code assignment (ROCA), the POCA is used in the CDMA technology. Since the number of the path is much less than the number of nodes, the length of the spreading code used in systems with POCA is greatly shorter than those of the spreading code used in systems with TOCA or ROCA. Simulation results show that compared to existing MAC protocols for UWASNs, the proposed MAC protocol achieves a higher throughput, and a lower end-to-end delay.

Power efficient ultra-wideband based wireless communication for wireless body area network applications

In wireless sensor networks, in order to satisfy the requirement of long working time of energy-limited nodes, we need to design an energy-efficient and lifetime-extended medium access control (MAC) protocol. In this paper, a node cooperation mechanism that one or multiple nodes with higher channel gain and sufficient residual energy help a sender relay its data packets to its recipient is employed to achieve this objective. We first propose a transmission power optimization algorithm to prolong network lifetime by optimizing the transmission powers of the sender and its cooperative nodes to maximize their minimum residual energy after their data packet transmissions. Based on it, we propose a corresponding power-optimized cooperative MAC protocol. A cooperative node contention mechanism is designed to ensure that the sender can effectively select a group of cooperative nodes with the lowest energy consumption and the best channel quality for cooperative transmissions, thus further improving the energy efficiency. Simulation results show that compared to typical MAC protocol with direct transmissions and energy-efficient cooperative MAC protocol, the proposed cooperative MAC protocol can efficiently improve the energy efficiency and extend the network lifetime.

Medium access control (MAC) protocols provide a means to nodes to access the wireless medium efficiently and collision free to the best of their ability. In this paper we provide a survey of MAC protocols developed for mobile ad hoc (MANETs) in the past based on certain methods and techniques such as multiple radios, multiple channels and specialized beamforming antennas. We discuss some of the MAC protocols designed for wireless sensor networks (WSNs) and their applicability in a MANET environment. There are some similarities between MANETs and WSN's in general but there is also critical differences between the two that affect the design of MAC protocols for both these networks. Traditionally, MAC protocols have been classified on the basis of two broad categories of contention free and contention based MAC protocols but a number of new algorithms proposed in the recent past merge the two schemes together in a single MAC solution and thus there is a need for a new classification approach. MANETs have their unique constraints and characteristics. In this classification, we will discuss various MAC solutions proposed in the past in the light of these constraints and characteristics. We do not intend to explain each and every protocol since the number of MAC solutions proposed in the past decade or so is very large. The purpose of this article is to give the readers a general idea on the various techniques and methods used in literature to develop MAC protocols for MANETs. The techniques range from algorithmic changes such as cross-layer design to enhancement in hardware such as directional antennas.