S1SIG Connection Setup Success Rate

Description

The S1SIG Connection Setup Success Rate KPI indicates the success rate of signaling connection setups over the S1 interface. This KPI includes counters such as the number of setup attempts of S1 signaling connections related to UEs and the number of successful setups of S1 signaling connections related to UEs.
The number of setup times of S1 signaling connections related to UEs is incremented by 1 each time when the eNodeB sends an INITIAL UE MESSAGE to the MME or receives the first message from the MME. INITIAL UE MESSAGE is the first S1 message that the eNodeB sends to the MME. It contains the NAS configuration information related to UEs, based on which the MME sets up S1 signaling connections for UEs. The first S1 message sent by the MME may be INITIAL CONTEXT SETUP REQUEST, DOWNLINK NAS TRANSPORT, or UE CONTEXT RELEASE COMMAND. Receiving any of these messages indicates that the S1 signaling connection is set up successfully.
As shown at point A in Figure 1, the L.S1Sig.ConnEst.Att counter is incremented by 1 when the eNodeB sends an INITIAL UE MESSAGE to the MME.
As shown at point B in Figure 1, the L.S1Sig.ConnEst.Succ counter is incremented by 1 when the eNodeB receives the first S1 message sent from an MME after sending an INITIAL UE MESSAGE to the MME.

Figure 1 signaling connection setup triggering point

Definition

The S1SIG Connection Setup Success Rate KPI is defined in Table 1. Note that the number of setup attempts of S1 signaling connections and the number of successful setups of S1 signaling connections are collected based on the description in Description.

Table 1 S1SIG Connection Setup Success Rate

Name	S1SIG Connection Setup Success Rate
Object	Cell/Radio Network
Formula	S1SIGS_SR = (S1SIGConnectionEstablishSuccess/S1SIGConnectionEstablishAttempt) x 100%
Associated Counters	S1SIG Connection Setup Success Rate =(L.S1Sig.ConnEst.Succ/L.S1Sig.ConnEst.Att) x 100%
Unit/Range	Percentage (%)