Filtered-Prefix OFDM

A new out-of-band (OOB) emission reduction technique for OFDM is presented which combined filtering of a cyclic prefix (CP) with appropriate complex subcarrier weighting. First, it is shown that for any filter shorter than the CP, filtered-OFDM can equivalently be decomposed into these two processings. This first directly leads to a low-complexity implementation of filtered-OFDM, while it also opens additional degrees of freedom to design OOB reduction methods non-equivalent to conventional filtering. Subcarrier weights can notably be smoothed to attenuate the original Gibbs effect of filtering, which enables trading off in-band distortion against OOB emission while maintaining the slope of the transition band.