Low complexity primary user protection for cognitive OFDM

A novel active interference cancellation (AIC) scheme for primary user (PU) protection is presented for application to cognitive OFDM systems, in which out-of-band radiation spilling over the PU protected band is to be minimized. A set of cancellation subcarriers are modulated by appropriate linear combinations of the remaining data subcarriers. The combination coefficients are fixed and need not be changed on a symbol-by-symbol basis, in contrast with previous AIC approaches. Thus, the optimization can be carried out offline, drastically reducing the online implementation cost and power consumption. The proposed scheme is shown through simulations to outperform current AIC solutions at a lower computational cost.