Tasneem Darwish

Traffic density estimation in vehicular ad hoc networks

Nowadays, vehicular Ad hoc Networks (VANETs) are gaining enormous research interest. Even though the leading reason for developing VANETs is traffic safety, many applications such as traffic status monitoring, road traffic management, routing and distribution of data, have been considered. Road traffic density estimation provides important information for such applications. Various infrastructure-based mechanisms were proposed to estimate traffic density relying on vehicle detection devices that require pre-deployment. However, as utilizing wireless communication capabilities in vehicles is developing rapidly, more accurate and real-time infrastructure-free density estimation methods are emerging day-to-day. Some of the infrastructure-free methods depend mainly on statistical estimations, while others are based on VANET communications and traffic flow information. In addition, clustering and group members counting are the main characteristic of a third type of infrastructure-free methods. This review paper explored different techniques and algorithms used in both infrastructure-based and infrastructure-free density estimation methods. Furthermore, the main features, limitations and critical issues for each density estimation method are depicted.

Traffic aware routing in vehicular ad hoc networks: characteristics and challenges

Vehicular ad hoc networks (VANETs) are gaining tremendous interest among researchers and industries. Although the main reason for developing VANETs is traffic safety, many applications such as traffic status monitoring, road traffic management, routing and distribution of data, have emerged. VANETs exploit multi-hop communications among vehicles to deliver data packets. However, with fast mobility and intermittent link connectivity between vehicles, efficient and reliable routing in VANETs is becoming a challenging task. In order to make routing protocols robust to frequent communication disruptions and aware of unstable traffic and network conditions, several new routing metrics have been integrated with routing protocols. Such protocols are called traffic aware routing (TAR) protocols as their routing decisions are influenced by traffic and network status. The goal of this paper is to review the most recent traffic aware routing protocols while emphasising on traffic and network conditions awareness issues. In addition, this review investigated TAR protocols capabilities and limitations in terms of routing process, routing metrics measurement, forwarding mechanisms and recovery techniques. Moreover, challenges, critical issues and open research problems were discussed in the “Challenges and issues to consider” sections.

Adaptive energy aware cluster-based routing protocol for wireless sensor networks

Wireless sensor networks (WSNs) have grown excessively due to their various applications and low installation cost. In WSN, the main concern is to reduce energy consumption among nodes while maintaining timely and reliable data forwarding. However, most of the existing energy aware routing protocols incur unbalanced energy consumption, which results in inefficient load balancing and compromised network lifetime. Therefore, the main target of this research paper is to present adaptive energy aware cluster-based routing (AECR) protocol for improving energy conservation and data delivery performance. Our proposed AECR protocol differs from other energy efficient routing schemes in some aspects. Firstly, it generates balance sized clusters based on nodes distribution and avoids random clusters formation. Secondly, it optimizes both intra-cluster and inter-cluster routing paths for improving data delivery performance while balancing data traffic on constructed forwarding routes and at the end, in order to reduce the excessive energy consumption and improving load distribution, the role of Cluster Head (CH) is shifted dynamically among nodes by exploit of network conditions. Simulation results demonstrate that AECR protocol outperforms state of the art in terms of various performance metrics.

An Energy-Efficient Mobile Sink-Based Unequal Clustering Mechanism for WSNs

Network lifetime and energy efficiency are crucial performance metrics used to evaluate wireless sensor networks (WSNs). Decreasing and balancing the energy consumption of nodes can be employed to increase network lifetime. In cluster-based WSNs, one objective of applying clustering is to decrease the energy consumption of the network. In fact, the clustering technique will be considered effective if the energy consumed by sensor nodes decreases after applying clustering, however, this aim will not be achieved if the cluster size is not properly chosen. Therefore, in this paper, the energy consumption of nodes, before clustering, is considered to determine the optimal cluster size. A two-stage Genetic Algorithm (GA) is employed to determine the optimal interval of cluster size and derive the exact value from the interval. Furthermore, the energy hole is an inherent problem which leads to a remarkable decrease in the network’s lifespan. This problem stems from the asynchronous energy depletion of nodes located in different layers of the network. For this reason, we propose Circular Motion of Mobile-Sink with Varied Velocity Algorithm (CM2SV2) to balance the energy consumption ratio of cluster heads (CH). According to the results, these strategies could largely increase the network’s lifetime by decreasing the energy consumption of sensors and balancing the energy consumption among CHs.

Green geographical routing in vehicular ad hoc networks: Advances and challenges

Abstract Information and Communication Technologies consume about 3% of the worldwide energy. Therefore, developing green communication systems is necessary for all sectors of technologies. In addition, as other wireless devices might inter-communicate with Vehicular Ad hoc Networks (VANETs), power constraints for such devices have to be considered. Moreover, with the introduction of full and hybrid electrical vehicles, efficient energy consumption in vehicles communication is becoming necessary. Although geographical routing is a dominant routing approach in VANETs, packets routing through multi-hop communications consumes most of the communication energy of vehicles’ wireless devices. This paper investigates the advances and challenges in green geographical routing protocols for VANETs, whereas existing protocols are classified to beacon based and beaconless. In particular, this review explored the different methods used by the green geographical routing protocols to reduced their energy consumptions. However, a considerable research work is required to improve VANETs green geographical routing and solve the problems highlighted in the “Challenges and critical issues” section.

A dynamic Energy-aware fault tolerant routing protocol for wireless sensor networks

In recent decades, cluster-based schemes have emerged as viable solutions for energy conservation problem in wireless sensor networks (WSN). However, most of the existing solutions incur imbalanced energy consumption and high network overheads. In addition, existing cluster-based solutions do not optimize route discovery based on the restricted resources of sensor nodes. Moreover, most of the cluster-based solutions perform periodical re-clustering for load balancing, which results in shortening network lifetime. This research paper presents a Dynamic Energy-aware Fault Tolerant Routing (DEFTR) protocol that exploits uniform-sized network partitioning based on network size and utilizes a multi-facet routing mechanism, which takes into consideration the residual energy, and position and link quality of neighbors. Furthermore, DEFTR not only offers reliable and energy efficient data routing but also supports fault tolerance. Simulation results demonstrate that DEFTR improved the network lifetime by 20.9% and throughput by 35%, also it reduced the delay by 29% and transmission cost by 46% in comparison to the existing work.