Description

The amount of data traffic in cellular networks has been increasing dramatically in the past few decades. To cope with the traffic increase, heterogeneous cellular network has been introduced to improve network performance by offloading traffic to access points (APs) with better link quality. The increase of energy consumption directly increases the greenhouse gas emissions which threatens the environment. Radio frequency (RF) energy transfer and harvesting techniques have recently become alternative methods to power the next generation wireless networks. An energy-efficient decision that considers the tradeoff between energy consumption and continuous transmission needs to be taken as to whether to switch the channels. The proposed scheme divides the available channels into two groups and performs sensing on both simultaneously, i.e., one group, consisting of the operating channel alone, is sensed using narrowband sensing by the sensor nodes, and the other group, consisting of the remaining channels, is sensed using wideband sensing by the SU. A vacant channel in the latter group is selected as a backup channel. An energy-efficient spectrum handoff scheme is developed for a sensor network-assisted cognitive radio network, where the SUs are energy-constrained nodes with an energy harvesting capability from the environment. When actual sensing process, select the nodes from active subset and while performing the scheduling process switched the active subset to sleep mode. The sensor nodes are performing sensing process based on the respective time duration. For using the PU activity, only few number of sensors are switched to active subset to sleep mode during the respective time slots.