A Constrained Optimization Approach to Compander Design for OFDM PAPR Reduction

In this paper, we derive new multi-component companders for reducing peak-to-average power ratio (PAPR) in orthogonal frequency-division multiplexing signals, using a constrained optimization approach. The new companders provide out-of-band power rejection performance improvements over current state-of-the art companders, while maintaining comparable demodulation performance. The newly designed companders are derived by minimally perturbing the Rayleigh signal amplitude distribution, while enforcing the constant power and probability density function constraints. The use of a multi-component approach to compander construction provides design flexibility, and expands the space of tradeoffs between demodulation performance, PAPR reduction, and out-of-band power rejection. Furthermore, the new companders provide solutions in operating regions where certain current companders fail to exist due to violation of one or more constraints; for example, solutions may be derived for cutoff amplitude values that are unobtainable using other companders. We formulate the constrained optimization problem for compander design and derive the compander and decompander forms. Through numerical simulation, we generate performance results demonstrating the capability of the new companders.