Yasuhiro Shimazu¹, Yushi Shirato² and Masahiro Muraguchi³, ^1,3Tokyo University of Science, Japan and ²NTT, Japan

A major drawback of orthogonal frequency division multiplexing (OFDM) signals is extremely high peak-to-average power ratio (PAPR). Signals with high PAPR lead to a lowering of the energy efficiency of power amplifiers and the shortened operation time causes a serious problem in battery-powered wireless terminals. We have found the CAZAC precoding makes the PAPR of M-array quadrature amplitude modulation (M-QAM) OFDM signals into the PAPR of M-QAM single-carrier signals. Therefore, it can dramatically improve the PAPR of OFDM signals. However, to satisfy the 3GPP-LTE specification of frequency spectrum, severe bandpass filtering of CAZAC-OFDM signal lead to unacceptable regrowth of the PAPR. The paper provides available control procedure for PAPR and spectrum managements. It is confirmed that the CAZAC-OFDM signal controlled by our procedure maintains enough low PAPR and can provide comparable spectral specifications in the downlink channel of 3GPP-LTE standard.

OFDM, CAZAC, PAPR, spectral specifications