PAPR Reduction With Mixed-Numerology OFDM

Abstract

High peak-to-average power ratio (PAPR) is a critical problem in orthogonal frequency-division multiplexing (OFDM). The fifth-generation New Radio (5G NR) facilitates the utilization of multiple heterogeneous bandwidth parts (BWPs), which complicates the PAPR problem even further and introduces inter-numerology interference (INI) between the BWPs. This paper proposes two novel schemes to reduce the PAPR of mixednumerology OFDM signals. The first scheme is an original enhanced iterative clipping-and-error-filtering (ICEF) approach that cancels efficiently the INI along with PAPR reduction. This allows to achieve efficient PAPR reduction while being compatible with well-known windowed overlap-and-add (WOLA) processing. The second scheme is based on fast-convolution (FC) processing, where PAPR reduction is embedded in the FC filtering carried out using overlapping processing blocks. This allows one to use any existing block-wise PAPR reduction method to reduce the composite signals' PAPR with arbitrary BWP waveforms, and it is thus especially well suited for processing mixednumerology composite waveforms carrying multiple BWPs with different OFDM numerologies. The performance of the proposed algorithms is evaluated in the 5G NR context, and the essential performance advantages are demonstrated and quantified.

SDR Prototype for Clipped and Fast-Convolution Filtered OFDM for 5G New Radio Uplink

“…As it will be shown with measurement and simulation results, FC-F-OFDM supports very low PAPR levels because it can effectively attenuate the OOB emission caused by clipping and therefore it provides higher transmission power than WOLA-OFDM, which confirms the discussion presented in [24]. For interested reader, more advanced techniques relating to, e.g., base-station implementation and enabling support for mixed-numerology signal PAPR reduction and transmission are described in [25].…”

Novel Iterative Clipping and Error Filtering Methods for Efficient PAPR Reduction in 5G and Beyond

“…Clipping noise and INI free reference any mechanism to prevent these issues and existing PAPR algorithms also do not support mixed-numerology utilization. In line with this, mixed-numerology ICEF method, presented in [11], effectively reduces PAPR in mixed-numerology systems. The mixed-numerology ICEF method includes an INI cancellation mechanism and interference cancellation is realized in the PAPR reduction process, resulting in an effective PAPR reduction for mixed-numerology systems.…”

“…Specifically, the subband CP-OFDM signals already suffer from high PAPR and, even if separate PAPR reduction is applied on each subband signal, final combination of the subband signals renders a significant increase in the total waveform PAPR. The PAPR reduction problem in mixed-numerology systems was introduced and preliminary addressed in [11], while a more comprehensive and efficient formulation of the mixednumerology PAPR suppression is presented in this article.…”

Performance Analysis and Optimization of Uplink Cellular Networks with Flexible Frame Structure

“…In [7], the authors formulate the cost function based on the long-term average SINR of a multinumerology system and propose a new resource allocation scheme that accounts for the Doppler and delay spreads. The authors in [8] proposed an analytical expression of peak-to-average power ratio (PAPR) distribution for a mixednumerology system and [12] presents two PAPR mitigation schemes for a multi-numerology cyclic prefix OFDM (CP-OFDM) system. In [9], the authors present a precoding scheme to mitigate INI in the downlink and, [10] considers multinumerology in non-orthogonal multiple access (NOMA) using successive interference cancellation.…”