Towards easier compliance with out-of-band emissions regulations

Orthogonal frequency division multiplexing (OFDM) is widely used in many wireless communications standards. One of OFDM drawbacks is its large out-of-band (OOB) power that may interfere with the neighbouring transmissions. Regulatory agencies avoid this problem by imposing regulations to insure that the OOB power levels are kept below a certain threshold. In this paper, we propose a solution that helps to meet these regulations with a better utilization of the available resources. The solution combines the cancellation carriers technique with digital filtering. The integration of the two techniques is fully investigated throughout the paper. A new algorithm is proposed which takes into account the transmitter filter in calculation of the cancellation subcarriers. Simulation results show that considerable reduction in the OOB emissions can be achieved using the proposed framework.