OFDM spectrum sculpting with active interference cancellation: Keeping spectral spurs at bay

Active interference cancellation (AIC) is an effective technique to shape the OFDM spectrum, providing deep notches over protected bands without affecting receiver design. However, AIC typically introduces spectrum overshoot, of concern if compliance with a spectral emission mask is required. Most AIC designs neglect these spectral spurs, focusing on minimization of out-of-band radiation. We present a novel design that explicitly takes spectral spurs into account. The resulting optimization problem is convex and can be efficiently solved, although for systems with a large number of subcarriers the computational effort can be significant. A suboptimal solution based on a previous AIC design with a maximum power constraint is also proposed. Its performance is close to optimal while obtained at a much lower computational cost, comparing favorably to previous schemes.