Improved energy detector based spectrum sensing for cognitive radio: An experimental study

Cognitive radio (CR) is a technology that addresses the problem of scarcity of spectrum and paves the way for efficient use of the same. In recent times, it has been observed that most research is focused on building theoretical models which are backed mostly by simulation results. In order to successfully support any theoretically developed model, it is necessary that the algorithm be tested in practical environment using hardware. Since some assumptions made to satisfy simulation requirements may not hold under practical circumstances, the implementation and testing of a theoretical concept is quite challenging. In this paper, we present experimental test results from our implementation of improved energy detector for single node and co-operative CR networks. The theoretical model is taken from [1], while GNU Radio and universal software radio peripherals 2 (USRP2) kits serve as software and hardware, respectively, in the implementation. Shadowed fading (due to obstacles and hidden node problem) makes single node sensing sometimes unreliable. Use of cooperation among secondary nodes, along with proper fusion rules, not only exploits the advantage of spatial diversity but also improves the reliability of spectrum hole sensing, as evident from the test results. It has been demonstrated by using the practical testing that cooperative sensing is better than single node sensing.