Constellation Compaction Design to Reduce Both PAPR and Average Power in OFDM Systems

This paper proposes a novel way to compact the constellation points in QAM modulation schemes and exploits this compaction to reduce the peak to average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. The compaction is accomplished using one dimensional product code (PC). Significant PAPR reduction is achieved by carefully mapping the points in the compact version of the constellation to their radial symmetric points and choosing for transmission signalling points which result in lower PAPRs. Specifically, the complementary cumulative distribution function (CCDF) of the modified OFDM signal shows about five dB improvement in PAPR at a clipping probability of 10−4 over the original OFDM signal. This performance is comparable to that in similar PAPR reduction schemes; however, it is achieved using simple single parity check (SPC) product code and at lower average power.