Improved Algorithms for Cancellation Carrier Optimization to Suppress the OFDM OOB Spectrum

Cancellation carriers (CCs) are known to be effective for suppressing the out-of-band (OOB) spectrum of an orthogonal frequency-division multiplexing (OFDM) signal and are useful to realize OFDM-based overlay systems. We show that the known minimum-mean-square-error (MMSE) algorithm is not sufficient to reduced the OOB spectral peaks in the vicinity of transmission band boundaries compared to a direct minmax algorithm and show that a weighted MMSE (WMMSE) algorithm can attain almost the same suppression performance as the direct min-max algorithm with the same computational cost as the MMSE algorithm.