Performance evaluation of different precoding matrices for PAPR reduction in OFDM systems

Abstract

Orthogonal frequency division multiplexing (OFDM) is an attractive technique for wireless communication systems due to its ability to mitigate frequency selectivity. However, OFDM suffers from high peak‐to‐average power ratio (PAPR) problem, which reduces the power amplifier (PA) efficiency or worse it degrades bit error rate (BER) performance and increases out‐of‐band radiation. In literature, there are different PAPR reduction techniques. Among them PAPR reduction by precoding matrices has small computational complexity along with high PAPR reduction gain. In this paper the six precoding matrices found in the literature are compared. Results showed that, all precoding matrices, except the one that based on square‐root raised cosine function (SRC), are not effective in terms of BER performance in presence of nonlinear PA, especially in high modulation order schemes (eg, 16‐QAM and 64‐QAM). However, precoding technique based on SRC matrix requires high data rate loss, to enhance the BER performance in presence of nonlinear PA. So, it can be said that, precoding technique worsens the problem especially in high modulation order schemes, except the SRC matrix‐based precoding technique, which cannot be used without high data rate loss.

A Novel Hybrid Precoding-Companding Technique for Peak-to-Average Power Ratio Reduction in 5G and beyond

“…The authors in [ 11 , 10 ] showed that SRC precoding ( Section 3.1 ) and Log companding ( Section 3.2 ) are the best precoding and the best companding techniques from BER and OOB-radiation reduction points of view. Therefore, they are selected to be hybridized in the proposed technique, and their parameters are adjusted to increase the reduction of BER and OOB-radiation.…”

“…Fortunately, the SRC matrix does not increase the distortion. However, it causes some data rate loss [ 11 ]. Precoding matrix R is given as: …”

“…Several PAPR reduction methods are introduced, such as clipping [ 4 ], Partial Transmit Sequence (PTS) [ 5 ], Selective Mapping (SLM) [ 6 ], Interleaving [ 7 ], Active Constellation Extension (ACE) [ 8 ], Tone Reservation (TR) [ 9 ], Tone Injection (TI) [ 9 ], companding techniques [ 10 ], and precoding techniques [ 11 ]. There are mainly three categories for PAPR reduction techniques: (i) coding techniques, (ii) Multiple Signal Representation (MSR) techniques, and (iii) adding-signal techniques [ 12 ].…”

“…On the other hand, companding techniques have small PAPR reduction gain with trivial computational complexity [ 10 ]. Also, precoding techniques have moderate PAPR reduction gain with small computational complexity [ 11 ].…”

“…Also, the SRC precoding outperforms all other techniques [ 11 ]. Hence, hybrid SRC-Log can better reduce the BER and OOB radiation than the previous precoding-companding techniques.…”