Mounib Khanafer

A Survey of Beacon-Enabled IEEE 802.15.4 MAC Protocols in Wireless Sensor Networks

IEEE 802.15.4 is the de facto standard for Wireless Sensor Networks (WSNs) that outlines the specifications of the PHY layer and MAC sub-layer in these networks. The MAC protocol is needed to orchestrate sensor nodes access to the wireless communication medium. Although distinguished by a set of strengths that contributed to its popularity in various WSNs, IEEE 802.15.4 MAC suffers from several limitations that play a role in deteriorating its performance. Also, from a practical perspective, 80.15.4-based networks are usually deployed in the vicinity of other wireless networks that operate in the same ISM band. This means that 802.15.4 MAC should be ready to cope with interference from other networks. These facts have motivated efforts to devise improved IEEE 802.15.4 MAC protocols for WSNs. In this paper we provide a survey for these protocols and highlight the methodologies they follow to enhance the performance of the IEEE 802.15.4 MAC protocol.

WSN Architectures for Intelligent Transportation Systems

The emergence of, and advancement in, integrated digital circuitry technology along with the development of efficient software algorithms made it possible to build small, lightweight wireless nodes equipped with embedded processors, sensors and radio transceivers. By densely deploying these nodes, in a highly distributed manner, we can build a Wireless Sensor Network (WSN). In this network, sensors collaborate in monitoring physical parameters or environmental conditions, such as temperature, sound, vibration, etc. Sensor nodes frequently report the data they capture to a central collection unit that analyses the data and takes appropriate actions if needed. Intelligent Transportation Systems (ITSs) emerged as a potential candidate for benefiting from the unique features and capabilities of WSNs. In ITSs, transportation infrastructure is supported with the ingenious achievements of computer and information technology to resolve severe situations like traffic congestion and cope with emergency conditions like major accidents. In this paper, we study the requirements for an efficient WSN architecture for ITSs, survey the WSN architectures proposed for this type of applications highlighting their strengths and weaknesses, and shed light on future directions in this field of research.

Adaptive Sleeping Periods in IEEE 802.15.4 for Efficient Energy Savings: Markov-Based Theoretical Analysis

The strict resource-constrained conditions under which Wireless Sensor Networks (WSNs) operate impose primary restrictions on power consumption. Algorithms implemented on sensor nodes should refrain from performing complex computations in order to prolong the lifetime of the overall WSN. The IEEE 802.15.4 standard is the appropriate suite of specifications that conforms to the distinguished characteristics of WSNs. This standard is suited for low data rate, low power, and low radio transmission ranges that are typical in WSNs. This paper proposes a modification to the IEEE 802.15.4 standard that achieves efficient power savings for the sensor nodes, better channel utilization, and improved reliability. The proposal is based on the addition of a sleeping state that allows nodes to save more power while reducing the level of packet collisions. The sleeping periods can be tuned such that the highest level of channel utilization is achieved. A theoretical analysis based on Markov chain is performed to derive a mathematical model for our proposal. Using Matlab software, we show that we can achieve high levels of channel utilization, enhance reliability, and save more power compared to the performance of the original IEEE 802.15.4 standard.

Intrusion Detection System for WSN-Based Intelligent Transportation Systems

The application of Wireless Sensor Networks (WSNs) in Intelligent Transportation Systems (ITSs) has been the topic of extensive research in the last decade. Various aspects of WSNs have been addressed in the context of transportation networks. In particular, the different aspects of security (confidentiality, integrity, and availability) strongly enticed the research devoted to ITSs. However, those efforts concentrated on preventive techniques constituting a first line of defense (like cryptography and authentication), which are effective in inhibiting the diverse malicious attacks. Relatively, little attention has been paid for employing a second line of defense that can detect intrusive behavior after successfully penetrating the first one. The latter line of defense is known as the Intrusion Detection System (IDS). While mature in wired and many types of wireless networks, IDSs are envisaged to have more opportunities in WSNs. In this paper, we study the incorporation of IDSs in WSN-based ITSs. We distinguish the characteristics of ITSs that affect the design of effective security measures and propose a novel IDS based on the WITS architecture (proposed in [1]).

A realistic and stable Markov-based model for WSNs

Certain Wireless Sensor Network (WSN) applications such as patient monitoring, smart grid and equipment condition monitoring require accurate estimation of specific WSN parameters such as the end-to-end delay, the reliability and the power consumption. The estimation of these parameters calls for an accurate and lightweight WSN model that is suitable for the low processing capabilities of sensor nodes. In this paper, we present a realistic and stable Markov based model for WSNs. We perform a comprehensive performance analysis using different traffic and network conditions. Furthermore, we test the accuracy of our model by conducting extensive simulations in environments that are equivalent to the analytical model. The proposed model takes into account the traffic generation probabilities and considers the impact of a finite MAC-level buffer size on the end-to-end delay, reliability and power consumption.

Modeling of variable Clear Channel Assessment MAC protocol for Wireless Sensor Networks

Toward devising a new efficient Medium Access Control (MAC) protocol that overcomes the shortcomings of the IEEE 802.15.4 standard MAC, we work on exploiting the Clear Channel Assessment (CCA) feature in a more efficient fashion. This paper proposes the Variable CCA MAC protocol; a new MAC protocol that increases the number of CCAs performed by a node beyond the standard value of two. We develop a Markov-based mathematical model that describes the functionality of this new protocol. We also validate our mathematical model through conducting extensive simulations that focus on a rich set of performance parameters, including the probability of collision, throughput, channel idle time, channel collision time, energy consumption, delay, and reliability.

MAC finite buffer impact on the performance of cluster-tree based WSNs

Certain Wireless Sensor Network (WSN) applications such as patient monitoring, smart grid, and equipment condition monitoring require accurate estimation of specific WSN parameters such as end-to-end delay, reliability and power consumption. The estimation of these parameters calls for an accurate and lightweight WSN model that is suitable for the low processing capabilities of sensor nodes. In this paper, we present a Markov-based model for WSNs that considers the impact of inserting a MAC-level finite buffer on the performance of WSNs. We perform a comprehensive performance analysis of the end-to-end delay, reliability and power consumption using different traffic and network conditions in star and cluster-tree WSN topologies. Furthermore, we test the accuracy of our model by conducting extensive simulations in environments that are consistent with the analytical model.

Extending Beacon-Enabled IEEE 802.15.4 to Achieve Efficient Energy Savings: Simulation-Based Performance Analysis

Wireless Sensor Networks (WSNs) operate in hostile environments under resource-constrained conditions. Power conservation is a primary factor that drives the design of these networks. Therefore, WSNs should not utilize complex algorithms that are power-hungry. The IEEE 802.15.4 standard is the appropriate suite of specifications that conforms to the distinguished characteristics of WSNs. This standard is suited for low data rate, low power, and low radio transmission ranges that are typical in WSNs. In this paper, we propose an extension to 802.15.4 that not only achieves efficient power savings, but also improves the reliability and the channel utilization in WSNs. In essence, we force each node that has just finished a successful packet transmission to sleep for a tunable period of time before contending for sending the next packet. We show through simulations that this behavior not only prolongs the lifetime of the WSN, but also achieves, compared to the original 802.15.4 standard, higher levels of channel utilization, better reliability, while preserving fairness among the nodes in the network.

Intrusion detection in WSN-based intelligent transportation systems

The application of Wireless Sensor Networks (WSNs) in Intelligent Transportation Systems (ITSs) has been the topic of extensive research in the last decade. Various aspects of WSNs have been addressed in the context of transportation networks. However, those efforts concentrated on preventive techniques constituting a first line of defence (like cryptography and authentication), which are effective in inhibiting the diverse malicious attacks. Relatively, little attention has been paid for employing a second line of defence that can detect intrusive behaviour after successfully penetrating the first line of defence. The latter line of defence is known as the Intrusion Detection System (IDS). In this paper, we study the incorporation of IDSs in WSN-based ITSs and propose a novel IDS based on the WITS architecture.

An Optimized WSN Design for Latency-Critical Smart Grid Applications

The growing popularity of the Internet of Things (IoT) systems such as the smart grid, Body Area Networks (BANs), and the Intelligent Transportation System (ITS) is driving Wireless Sensor Network (WSN) systems to the limit in terms of abilities and performance. WSNs were initially designed for low power, low data rate, and latency-tolerant applications. However, this paradigm is changing because of the nature of the new applications. Therefore, instead of only focusing on power-efficient WSN design, researchers and industries are now developing Quality of Service (QoS) protocols for WSNs. In addition to that, latency- and reliability-critical protocol designs are also becoming significantly important in WSNs. In this paper, we present an overview of some important smart grid latency-critical applications and highlight WSNs implementation challenges for these smart grid applications. Furthermore, we develop and evaluate two novel optimization models that solve for the optimum values of the end-to-end latency and power consumption in a clustered WSN given lower bounds on reliability and other network parameters.