Implementation of Real-Time Interference Reduction Techniques for Cognitive Radios

In dynamic spectrum access (DSA) networks, users are allowed to access the available spectrum while keeping neighboring transmissions not interfered. Orthogonal frequency division multiplexing (OFDM) is an ideal candidate for DSA network. However, one of OFDM drawbacks is its large out-of-band (OOB) power levels that can potentially interfere with neighboring transmissions. In this demonstration, two OOB interference reduction techniques are used. Each technique, individually, can achieve significant reduction in the OOB emissions, however, at the expense of degrading the performance of the OFDM system. Combining the two techniques provides better utilization of the available resources. The Chosen techniques do not involve excessive computations which make the combination suitable for real-time transmissions. The demonstration is based on real-time implementation of the two techniques on the reconfigurable Iris 2.0 software defined radio along with the universal software radio peripheral (USRP-N210) as the hardware front-end.