Event-based performance monitoring for inter-system cell reselection: A SON enabler

It has been observed that in overlaid 3G/2G networks certain user equipments (UE) may stay camped on 2G for long periods despite the fact there is available 3G coverage. In this paper we present a framework to enable network operators to identify these occurences, not easily recognized using counter-based observability. The proposed methodology relies on the post processing of performance monitoring (PM) events from the radio access and core networks, feature provided by most major network vendors. Based on that, new key performance indicators (KPI) are defined e.g. the time UEs camp on 2G. Then, we show how these event-based KPIs may be used as inputs to self-optimization algorithms, functioning as a self-organizing networks (SON) enabler. Results are shown using data from live 3G/2G networks.