Abstract
This paper proposes an improved metric-based active constellation extension scheme for peak-to-average power ratio (PAPR) reduction in orthogonal frequency-division multiplexing (OFDM) systems. In the proposed scheme, we first compute metrics of the real and/or imaginary parts of each extendable frequency-domain symbol (i.e., exterior constellation points) for evaluating their contributions to the time-domain peak samples, and then select an appropriate number of terms (real or imaginary parts) with the largest metrics for extension. As compared to a previous related work, the proposed one adopts refined metrics for active constellation extension and adaptively adjusts the extension factors during each iteration. These features make it gain significant performance improvement in PAPR reduction, with a little increase in the computational complexity and the average power.