ABSTRACT
A wireless sensor network (WSN) consists of a set of sensor nodes that are deployed in a field and interconnected with a wireless communication network. Traditionally, almost all WSNs operate in unlicensed frequency bands, which are also used by wireless applications, such as Wi-Fi, Bluetooth WiMAX, and ZigBee. Sensing data without knowing the sensor location are meaningless; hence, localization deals with determining the locations of wireless devices in a WSN. Traditionally, wireless networks run with fixed spectrum assignment policy regulated by government agencies. A spectrum is assigned to service providers on a long-term basis for large geographical regions. While sensing the spectrum, the two major sources of getting degraded signals are multipath and shadowing for a given frequency. Sensing of backup channel has to be done regularly in order to make sure that the backup channel is readily available and clean.
