Implementation of Gradient Broadcast (GRAB) in NS-2 and Simulation Construction

Abstract

Recent advancement in wireless communications and electronics has enabled the development of Sensor networks, a network that consists of a number of sensors spread across a geographical area. Each sensor has wireless communication capability and some level of intelligence for signal processing and networking of data. The application of sensor networks is wide spread, from disaster recovery to military installations. A lot of research is being carried out in this field, the results of which are the proposed routing protocols for such networks. These are Directed Diffusion, Gradient Broadcast (GRAB) and Two Tier Data Dissemination (TTDD). GRAB is a protocol designed specifically for robust data delivery in face of unreliable nodes and fallible wireless links. This is made possible by constructing a forwarding mesh, multiple nodes forwarding the same message. The redundancy in forwarding messages gives robustness but also increases the overall energy consumption of the sensor network. The energy consumed by nodes in a sensor network using GRAB is greatly affected by variation in topology size, node density and distance between nodes. The deployment of sensor networks should be done by balancing the node density and also the distances between the nodes, as both these factors greatly affect the energy usage in the network.