Constrained Clipping for Crest Factor Reduction in Multiple-user OFDM

Crest factor reduction (CFR) techniques aim to solve the high peak-to-average power ratio (PAR) problem encountered in the transmission of modern communication signals such as orthogonal frequency division multiplexing (OFDM). Constrained clipping is a promising CFR technique that is capable of large PAR reductions while guaranteeing that EVM and spectral mask constraints are met. In this paper, we analyze the computational complexity of constrained clipping and show that it is a practical technique that can be readily implemented. We then demonstrate its performance in a multiple-user OFDM environment such as the IEEE 802.16 OFDMA forward link. More than 5 dB of PAR reduction can be achieved in a four-user scenario