A Low-Complexity Peak-to-Average Power Ratio Reduction Technique for OFDM Systems Using Guided Scrambling Coding

Abstract

One major drawback of orthogonal frequency division multiplexing schemes is the high peak-to-average power ratio (PAPR) of the output signal. Selected mapping (SLM) and partial transmit sequences (PTS) are two important techniques for reducing PAPR, but they need to transmit side information to indicate how the transmitter generates the signals. Guided scrambling (GS) SLM and GS-PTS techniques use augmenting bits to set the scrambler's initial condition. With different patterns of the augmenting bits, different candidate signals can be generated. GS-SLM and GS-PTS do not require the transmission of side information, but they still need a bank of inverse fast Fourier transforms (IFFT's), i.e., involving high computational complexity. In this paper, we focus on reducing the high computational complexity of the GS-SLM and GS-PTS methods. We separate the operations of the augmented data word into the operations of the augmenting bits and the operations of the source data word. Different augmenting bits are processed in advance and the results are saved into a read-only memory (ROM). The proposed methods only need one IFFT, few adders, and a ROM and thus significantly reduce the computational complexity of the original GS-SLM and GS-PTS methods. The simulation results also show that the proposed GS-SLM and GS-PTS methods have almost the same PAPR reduction performance as the original ones.

Guided Scrambling As a Peak to Average Power Ratio Reduction Technique for Digital Video Broadcasting-Terrestrial 2

“…A previous research paper elaborated on the use of Guided Scrambling to reduce PAPR in OFDM but the technique was limited to N=256 subcarriers, QPSK modulation mode and an unstated number of information bits [4]. Another paper on the subject utilised an OFDM system of N=256 subcarriers, BPSK modulation and again an unstated number of information bits [5]. There is a need to state the length of source word or information bits as it may affect the scrambling process and overall design.…”

A partial transmit sequence technique with error correction capability and low computation

“…Consequently, methods to improve the PAPR reduction performance of this approach are also popular topics in PTS research. In addition, methods to integrate side information into transmission signals or protect the side information in communication channels so that the receiver can restore the transmitted data correctly are also topics of focus .…”