Nonlinear Effects of Wireless Transceivers

Kapitel i bok, 2019

All communication transceivers suffer from nonlinearities in the analog components, such as amplifiers, mixers, ADCs/DACs, etc. Such nonlinearities lead to distortion of the communication signals, and may lead to the transceiver interfering with victims operating at neighbor frequencies. The effects of nonlinearities have been a focus area since the start of digital mobile communication, and particularly the power amplifier in the transmitter has received much of attention. However, with 5G there are a few features that lead to a change in how nonlinearities are affecting the system. The usage of large antenna arrays, the introduction of millimeter-wave frequencies, and the large signal bandwidths all lead to new effects due to nonlinearities - some beneficial, some problematic. In this article, we present a comprehensive overview of the underlying reasons for nonlinearity and how to model them. We study the effects of nonlinearity in several scenarios, including single- and multi-antenna transceivers, phased array and hybrid digital/analog beamforming, single- and multi-carrier signaling, and concurrent multi-band signaling, and we briefly discuss compensation of the effects.