PAPR reduction using integer structures in OFDM systems

The problem of reducing the peak-to-average power ratio (PAPR) in an orthogonal frequency division multiplexing (OFDM) system is considered. We design a cubic constellation, called the Hadamard constellation, whose boundary is along the bases defined by the Hadamard matrix in the transform domain. Then, we further reduce the PAPR by applying a selective mapping (SLM) technique. The encoding method, following the method introduced by H.K. Kwok (see "Shape Up: Peak-Power Reduction via Constellation Shaping", PhD Dissertation, University of Illinois, 2001), is derived from a decomposition, known as the Smith normal form (SNF), and has a minimal complexity. This new technique offers a PAPR that is significantly lower than that of the best known techniques without any loss in terms of energy and/or spectral efficiency and without any side information being transmitted. Moreover, it has a low computational complexity.