A Method for Power Amplifier Distortions Compensation at the RX Side for the 5G NR Communication Systems

Abstract

For the past years, the Internet of Things (IoT) supported by 5G technology, has been expanding rapidly across a wide range of services, enabling inter-object connectivity for the automotive industry, consumer electronics, transportation, logistics sectors, and manufacturing. With the increasing ubiquitous usage of various small-sized sensors, manufacturing cost of each element taken remains a critical aspect. Relatively low price of individual elements is the key for enabling tightly connected environment, but may severely affect RF chains quality as well as overall performance. With 5G expansion to the sub-THz bands, power amplifier nonlinearity may significantly limit system performance even in high- grade devices, due to power amplifier design limitations. Multiple studies were done to mitigate nonlinearity impact, both at the transmitter (TX) and receiver (RX) sides. Many solutions propose for evaluation and further compensation of the PA nonlinearity effects, via decision-directed feedback, training or even statistical processing of the received signal. However, with knowledge of the PA nonlinearity function at the receiver side, the processing may be simplified by the application of the reverse function to the equivalent signal in the time domain. In this paper we propose a method for PA nonlinear distortion compensation at the RX side, which can be adjusted for several signal waveforms adopted in 5G NR (New Radio) standard, such as CP-OFDM, DFT-S-OFDM, and others. The simulation results presented demonstrate performance improvement both for the sub-THz PA models and models for the 30-70 GHz band.