Key Performance Indicators for QOS Assessment in TETRA Networks
  Key Performance Indicators (KPIs) are widely used by GSM and UMTS carriers with the aim of evaluating the network performance and the Quality of Service (QoS) delivered to users. TETRA networks are basically designed to provide telecommunication services to Public Safety & Security (PSS) organizations, thus the compliance of the QoS levels required by these clients is usually critical. Despite that, the use of KPIs to assess the network performance and the QoS achieved in TETRA systems is not very common. This paper not only states the need of monitoring and evaluating these parameters, but also introduces a set of KPIs which is considered necessary and sufficient in order to allow TETRA operators to be aware of whether provided services meet the QoS requirements established by end users. 
Jose Dario Luis Delgado and Jesus Maximo Ramirez Santiago
cs.NI