Amping Up, Saving Power: Digital Predistortion Linearization Strategies for Power Amplifiers Under Wideband 4G\/5G Burst-Like Waveform Operation

Abstract

ourth-generation (4G) communication systems based on orthogonal frequency division multiplexing (OFDM) and the proposed backwards compatible fifthgeneration (5G) variants, like filter-bank multi-carrier (FBMC), are based on modulation techniques that allow significantly increased spectral efficiency and capacity in mobile radio access networks (RANs). However, the use of these modulation techniques impacts the requirements of the radio base stations, which have been traditionally the most energy consuming-element of mobile networks, accounting for up to 80% of the energy consumption of RANs [1]. Non-constant envelope-modulation techniques with high peak-to-average power ratios (PAPRs) require highly linear power amplifier (PA) amplitude and phase responses to fulfill stringent spectral mask and modulation accuracy requirements. This is often achieved with significant PA back-off, which considerably reduces PA efficiency because the PA's maximum efficiency is achieved near the saturation point. The adoption of gallium nitride (GaN) PA technologies and use of digital linearization techniques are playing a key role in building more efficient base

Predistortion-Based Linearization for 5G and Beyond Millimeter-Wave Transceiver Systems: A Comprehensive Survey

“…On the other side, the 5G-CA schemes have imposed major limitations on DPD wideband running capabilities, especially in targeting nonlinearities of the gigabit broadband spectrum. In this way, it is important to determine an appropriate rate of sampling bandwidth in the presence of memory effects (MEs) to meet the target performance of intra-band (within carrier), and inter-band (outside carrier) signal modulations [28], [29]. It is also worth highlighting that the worst-case scenario of ambient MEs occurs in the wideband systems, where the inter-band distortion coincides with DPD modulated intra-band signal [15], [30].…”