Dina M. Ibrahim

Modelling of CVBF algorithm using Coloured Petri Nets

Modelling is a general method used throughout the development of systems. Numerous modelling languages were proposed for analyzing and building systems. Petri Nets language is considered as one of the formal modelling and analysis techniques. These techniques allow users to do both the performance evaluation and model checking. Coloured Petri Nets (CPN) is one of the modelling languages especially for discrete-event systems. In this paper, we use Coloured Petri Nets to model and analyze the behavior of the Clustering Vector-Based Forwarding (CVBF) routing protocol in Underwater Wireless Sensor Networks (UWSNs). Our proposed model is tested and verified by the state space statistics analysis which results that the proposed CPN model is liveness, responsiveness and free from deadlocks. The results of the performance evaluation of the proposed model demonstrate the proposed model capability to increase both the packet delivery ratio and the average end-to-end delay.

A communication load balanced dynamic wireless sensor network topology management algorithm based on AODV (CLB-AODV)

In this paper, a communication load balanced dynamic topology management algorithm (CLB-AODV) is proposed to extend the wireless sensor network (WSN) lifetime via managing the participation in communication process among all nodes in the network. The idea is that, each time there is a failure in the network topology; the topology is adjusted only on-demand by choosing the best path according to paths weights between source and destination nodes. The path weight reflects the nodes participation in communication process through the lifetime of the nodes. Our algorithm is based on the routing protocol AODV instead of using a separate protocol for dynamic topology control in order to reduce the routing load among nodes. Simulation results show that CLB-AODV can prolong the lifetime of the network, increase the number of alive nodes and reduce the average routing load when compared with some of the most powerful recent algorithms.

Contention-based MAC protocol in UWSNs: Slotted_CS_ALOHA proposed protocol

Energy in MAC protocols becomes an important research issue because sensor nodes are mostly take their power from batteries that are not easily to be recharged. The aim of this paper is to improve MAC protocol in underwater sensor networks by enhancing the performance of ALOHA protocol, which considered as one of the most popular MAC protocols. This work proposed a method for preserving the energy consumption in underwater sensor networks. We propose a protocol that we called Slotted_CS_ALOHA. This approach based on three stages before the original Aloha cycles is working, the first stage is buffer that if the node has any numbers of packet it will be able to send them continuously to the buffer. The second stage has two parallel steps the first one is a slot time that check if slot time begins or not. The second one is CS to check if channel free or not by sending small message (RTS and CTS) to make sure that channel is free. The third stage considered as another buffer. Our simulation results demonstrate that the proposed protocol efficiently reduces energy consumption especially in dense networks, increases the throughput ratio, increases the alive nodes ratio, and reduces the dropped node. On the other hand, our proposed cannot decrease the average delay.

Enhancing DCCP-TCP-like mechanism for Wireless Sensor Networks

Congestion is a significant problem that faces streaming media applications in Wireless Sensor Networks (WSN). This problem occurs when the sensor receives traffic that exceeds its maximum forwarding rate causing more packet loss, more delay and overall quality degradation. The Datagram Congestion Control Protocol (DCCP) is a congestion control protocol that works on the transport layer and is suitable for use by multimedia applications. DCCP supports many congestion control mechanisms that the application can choose among them according to the type of data being transmitted. In this paper, we propose an algorithm to enhance the performance of DCCP-TCP-like mechanism by adapting slow start threshold (ssthresh) and congestion window (cwnd) with respect to the reset function. The proposed algorithm is analyzed with respect to some important metrics like: packet loss, time delay and consumed energy using the NS-2 simulator. The simulation results indicate that the proposed algorithm can achieve better results than the native mechanisms. We found, during our experiments, that the initial values of ssthresh, cwnd and Retransmission Time Out (RTO) during the reset function have significant effect on the packet delivery ratio (or packet loss). So, determining these values is vital for the stability of the network.