Spectrum sensing in cognitive radio using Labview and NI USRP

Cognitive Radio(CR) is an adaptive radio that detects empty or white bands available in wireless spectrum and sets transmission parameters to utilize radio spectrum more efficiently. In this paper the spectrum sensing or presence of primary user (PU) is detected using a Labview code and universal software radio peripheral (USRP). We have used NI USRP-2943R device as a transceiver. It has two channels and frequency range of both transmitter and receiver is 1.2 GHz to 6 GHz. The method which is used to detect primary user is called Energy Detection. In energy detection method we set a threshold energy level which depends upon noise floor and then we compare the energy detector output with it to detect the presence of primary user. To implement the cognitive radio we have made use of ISM spectrum which is a free spectrum and by performing several experiments we have set a threshold value to compare with detectors output. We have used power spectrum which shows the distribution of power levels of signals corresponding to their frequencies. Ultimately depending upon whether the PU is present or not the secondary user gets to utilize a channel.