Energy and spectral efficient cognitive radio sensor networks for internet of things

Abstract

The energy-efficiency of wireless sensor devices and the scarcity of wireless spectrum are two major design considerations in any wireless sensor network (WSN). Since the sensors devices are battery powered and often are embedded into the system permanently, replacing the dead battery is often difficult. Most of the battery power consumed usually in cognitive radio sensor network (CRSN) is due to the transmission of the sensed attributes and forwarding of other sensor nodes data to the upper layer or to the base station which is called cluster head (CH) role in clustered topology of the network. In this proposed work we propose two methodologies for how a cognitive sensor node acts during the network. One mode, it can operate fully which is known as full capability mode (FCM). In this mode a sensor node can be selected as CH only if its residual energy level is upper than a specified fixed threshold. Role of CH assigned is also based upon nodes previous assignment order, residual energy as well as their Euclidean distance to base station (BS) too. In case sensor node residual energy drops from the threshold, it is shifted to the reduced capability mode (RCM) where it cannot be eligible for CH role, neither it transmit data packets as in FCM mode, instead it harvest energy and stay in charging mode till it’s all neighbour node’s residual energy are drops or it gains enough power to resume in FCM mode. In this way, not only the network lifetime increases but also overall network energy is balanced.