Optimization of Random Access in 3G Long Term Evolution

Abstract: Before a mobile can commence services it needs to have access to a base station. The access method is often referred to as random access (RA). One way to measure the performance of the RA procedure is the access delay (AD) of the mobiles, where AD is the time from which a mobile wants to start a RA attempt until it has received access. There are different approaches to optimize the RA procedure. Manual optimization is possible but costly. Automated optimization is preferable because of the lower costs and the possibility to change configuration fast in the base station when the operational conditions change. This thesis focuses on automated optimization of the RA procedure with regard to AD. A controllability and observability study of AD is first presented in this thesis. The controllability study shows that AD can be controlled by a number of RA parameters, whereas the observability study show that AD cannot always be correctly observed. The next part of this thesis presents a controller synthesis, where three different controllers are presented to control a specified percentile of AD. It is shown, through experiments, that the controllers derived can be used to optimize the RA procedure with regard to AD.