Low-Complexity SLM PAPR Reduction Approach for UFMC Systems

Abstract

The universal filtered multicarrier (UFMC) system is one of the novel candidate waveforms for 5G systems. UFMC is expected to achieve low latency, robustness against frequency offset, and reduce out-of-band (OoB) radiation that leads to a higher spectral efficiency. Although, the UFMC system offers many advantages as mentioned before, but being a multicarrier transmission technology, it suffers from high peak-to-average power ratio (PAPR). In this paper, a modified selected mapping (SLM) approach with low-complexity is proposed for reducing PAPR in UFMC systems. The main idea of the proposed modified SLM (P-SLM) approach is to utilize the linearity property of the UFMC modulator. The P-SLM approach generates U w alternative UFMC waveforms using U m UFMC modulators, where U m is the square-root of U w. Therefore, the computational complexity of the P-SLM approach is reduced compared to the existing SLM based PAPR reduction approaches for UFMC systems. The P-SLM approach is compared to the other approaches found in the literature in terms of PAPR reduction ability, bit error rate (BER) performance, and the computational complexity.

PAPR Reduction in UFMC for 5G Cellular Systems

“…For example, Dcomp-SLM gains about 1 dB over the NSLM at Pr(PAPR > PAPR 0 ) = 10 −4 , N = 512 sub-carriers and input-back-off (IBO) = 7 dB and U = 6 phase vectors. Furthermore, the proposed Dcomp-SLM technique is better than the E-SLM and P-SLM approaches that were proposed in [20,37], respectively, by approximately 0.5 dB at 10 −4 CCDF under the same simulation parameters.…”

“…We propose a Dcomp-SLM algorithm to mitigate PAPR in UFMC systems. This method not only maintains the PSD of the UFMC system but also reduces the complementary commutative-distribution function (CCDF) to remarkable levels compared to recent proposed solutions [20,37].…”

“…Nonetheless, UFMC suffers from high PAPR arising from the usage of multi-carrier transmission [11]. Several techniques for PAPR reduction were proposed in the literature [20,21]. These techniques can be classified as either signal distortion [22,23], encoding [24], or probabilistic methods [25,26].…”

“…Additionally, an efficient piecewise non-linear companding transform for PAPR reduction in UFMC systems has been proposed in [36], where the proposed companding method shows an efficient trade-off between PAPR reduction and other system performance metrics such as BER and OOB radiation. In [20,37], the authors proposed a low complexity SLM-based PAPR reduction approach for UFMC systems, in which it utilizes the linearity property of the UFMC modulator. However, to the best of our knowledge, non acceptable solution has been yet provided to reduce the high PAPR while protecting the signal from the OOB radiation effect and keeping the BER performance to its minimum levels.…”

“…Thereafter, we compare the performances of both OFDM and UFMC systems in terms of PAPR, BER, error vector magnitude (EVM), and power spectral density (PSD) in the presence of Rayleigh fading and additive white Gaussian noise (AWGN) channels. Moreover, the proposed Dcomp-SLM scheme is compared with the reduced-complexity efficient SLM (E-SLM) and the modified SLM (P-SLM) approaches in [20,37] under the same simulation parameters. The main contributions of this paper are as follows:…”