Out-of-Band Power Suppression for Cyclic SLM with Delayed Correlation and Matched Filter

Abstract

Orthogonal frequency-division multiplexing (OFDM) has been used in many communication systems. However, OFDM suffers from undesirable high peak-to-average power ratio (PAPR) as it uses inverse discrete Fourier transform (IDFT) operation at the transmitter. One of the simplest schemes of the PAPR reduction is the cyclic-selective mapping (SLM). This paper presents cyclic-SLM without side information (SI) which employs delayed correlation with a matched filter (DC-MF) at the receiver. The cyclic-SLM combines the original OFDM signal and its cyclically shifted ones. In the previous conventional cyclic-SLM, the cyclically shifted signal samples are multiplied by a phase sequence which is drawn from Barker code sequence. However, this scheme results in higher out-of-band (OOB) power leakage. In this paper, we propose to use different phase sequence for each OFDM symbol in one OFDM frame to overcome the OOB problem. As a consequence, multiple matched filters are used at the receiver. Simulation results show that the proposed method has the same OOB as the conventional OFDM. In addition, we also analyze the performance of the proposed scheme in terms of the PAPR reduction and bit error rate (BER).