ETSHRA: Energy Efficient Threshold SensitiveHierarchical Routing Algorithm for Cognitive WirelessSensor Networks

Abstract

Today's wireless networks are regulated by government organizations where a fixed spectrum is assigned to license holders for a specific geographic region. The spectrum usage is dominated in some areas and a major amount of it is underutilized. The spectrum utilization ranges from 15% to 85% depending on the area and time of usage. The limited spectrum availability and its inefficient use have lead to the development of new approaches where licensed and unlicensed networks can exist in the same area and utilize the existing spectrum in the most efficient manner. One such approach is to use a spectrum sensor network to sense the spectrum availability in the primary network (licensed network) and provide the details to the cognitive wireless sensor network (secondary network or unlicensed network). In this paper we propose a novel algorithm for cognitive wireless sensor network to use the available spectrum in the primary network in an opportunistic manner. The main aim of our algorithm is to optimize the data aggregation and transmission process by using hard and soft thresholds while routing the data in the cognitive wireless sensor network. Our approach when applied to a sensor field reduces the amount of data being transmitted throughout the network and helps in increasing the lifetime of the network. This helps the cognitive wireless sensor network in making quick and right decision while selecting the channel in which it can operate in the primary network. We show that our approach outperforms other existing solutions such as leveling, gossiping and PASCAL up to 35% and is more energy efficient than these solutions. Recent advances in wireless sensor networks (2) have lead to many new algorithms where energy utilization and reliability were the key areas of concern. These routing protocols may differ based on the application and the network design. With the reduction in the size and cost of sensor nodes and the increasing need to monitor the process in remote areas, cognitive wireless sensor networks are gaining importance. For this reason, cognitive wireless sensor networks should be set up in such a way that the nodes utilize least amount of energy and maximize efficient utilization of the resources to increase the lifetime of the network and achieve reliability. Recent advances in wireless communications show that spectrum sensors can be deployed in a cognitive radio environment to support the existence of both licensed and unlicensed users in the same area by providing information on current spectrum occupancy. Spectrum sensor nodes can detect the temporally unused spectrum (also known as spectrum hole or white space) in the licensed band of the primary network and provide this information to the