 Nokia Networks, 'Nokia Active Antenna Systems: A step-change in base station site performance', Retrieved from http://networks.nokia.com/sites/default/files/document/nokia_active_antenna_systems_white_ paper.pdf (last accessed August 2015). LTE Key Performance Indicator Optimization Jussi Reunanen, Jari Salo and Riku Luostari 12.1 Introduction Key Performance Indicators Physical Layer Optimization 12.4 Call Setup E-RAB Drop Handover and Mobility Optimization Throughput Optimization High-Speed Train Optimization Network Density Benchmarking 12.10 Summary References 12.1 Introduction Network performance is measured using a set of key performance indicators (KPIs). The selection of those KPIs should be done in such a way that they measure both the end-user- experienced performance and the resource utilization, that is, how much of the resources are used in order to deliver certain end-user-experienced performance. Sacrificing resources for signalling to maximize, for example, the call setup success rate (CSSR) is not feasible in the long run. Instead minimum resource utilization to maximize the KPI performance should be the optimization target. In this chapter the common LTE KPIs and methods to improve those are discussed. The KPI performance is further discussed in Chapter 13 where the impact of high traffic event on various KPIs is analysed. LTE Small Cell Optimization: 3GPP Evolution to Release 13, First Edition. Edited by Harri Holma, Antti Toskala and Jussi Reunanen. © 2016 John Wiley & Sons, Ltd. Published 2016 by John Wiley & Sons, Ltd. LTE Small Cell Optimization The most common call performance KPIs, based on network statistics and drive test, are introduced. Drive test based KPIs are used for a pre-launch network. However, due to increasing traffic load after network launch, network statistics can be leveraged for performance improvement in the network. Drive testing effort can then be directed towards coverage and performance verification following physical layer optimization and some parameter changes. 