Opportunistic Configurations of Pilot Tones for PAPR Reduction in OFDM Systems

Abstract

This paper introduces a peak-to-average power ratio(PAPR) reduction methodology in orthogonal frequency division multiplexing (OFDM) systems by deploying pilot tones in PAPR optimized configurations. Conventionally, the pilot tones in OFDM are used for channel estimation and carrier tracking. In this paper, in addition to maintaining their conventional functions, pilot tones, i.e., their signaling points and positions, are carefully chosen to "balance" the envelope peaks in the OFDM frame. Specifically, two methods are proposed, where both the magnitude and the phase information of the pilot tones are modified to reduce the PAPR of the OFDM signal. In the first method, similar to conventional applications, the pilot tones occur at the deterministic, known to the receiver, subcarriers whereas in the second method, a relaxation in the position of pilot tones is allowed. The proposed schemes achieve significant reduction in the PAPR, as measured using the complementary cumulative distribution function (CCDF) of the OFDM signal, without affecting the data rate of the system.