In today’s era, development in wireless communication systems has now become an emerging field for research. Now every user requires high data rate having low cost with greater efficiency. To achieve all this requirements in current communication system we have to make lot of hardware change in systems. So instead of using current communication system we are using cognitive radio approach which helps us to achieve greater flexibility and robustness. By implementing SDR we are replacing hardware part by software. GNU radio is open source, so we chose GNU radio and a device named Universal Software Radio Peripheral (USRP). SDR is more flexible as compared to conventional radio and can perform signal processing having low latency at the minimum cost. Thus by implementing SDR we spectrum mobility can be achieved.