Effects of phase discontinuity due to power amplifiers on a WCDMA uplink
Liu Shi-jia · Chalmers Publication Library (Chalmers University of Technology) · 2015
The major objective of this study is to identify and understand the way that a power amplifier affects a signal at a WCDMA uplink.More specifically, the phase distortion that is produced when a signal enters the power amplifier in order to get amplified and then sent over a channel.An end-to-end link simulator is built in order to come as close as possible to a realistic system.Furthermore, the phase distortion is modelled and added to the signal in order to finally study the performance of the system in terms of bit error rate.The study was conducted at Ericsson AB in Gothenburg.Insights about real WCDMA systems were used in order to implement a realistic simulator.The thesis introduces the WCDMA air interface and describes it in terms of the components that were used for the simulations.Matlab was used as the main simulation platform for all the components of the simulated link.The phase distortion was modelled with models that already exist in the literature, and is added to the simulation chain.The study was performed at baseband frequencies.The channel knowledge was assumed to be perfect.For this study only one user was simulated.Results were acquired which showed that the simulated WCDMA air interface system can easily cope with the phase distortion of a typical power amplifier considering QPSK.The distortion that was produced was not able to degrade the robust performance of the system.Based on our simulation results about the power amplifiers that are nowadays used for the uplink user equipments, there should be no need of taking further measures to cope with the phase distortion.