apacity grant. 12.4.2 RRC Connection Setup The RRC connection setup success rate can be measured as the number of received (by eNodeB) RRC connection setup complete (message 5) messages divided by the number of received (by eNodeB) RRC connection setup request (message 3) messages. Poor performance of RRC LTE Key Performance Indicator Optimization Random access setup RRC connection success rate setup success rate Day 1 Day 2 Day 3 Figure 12.14 Average random access setup success rate and average RRC connection setup success rate in a small cluster of sites over a period of 3 days connection setup success rate can be caused by message 5 reception problems at eNodeB or message 4 (RRC connection setup message) reception problems at the UE. Problems in receiving the respective message capacity grant by the UE or scheduling request (SR) reception (for message 5) problems at the eNodeB can cause problems in RRC connection setup success rate. Any capacity limitation in terms of number of RRC-connected users reduces RRC connection setup success rate as shown in Chapter 13. Figure 12.14 shows one example of traffic increase impact on the random access setup success rate and RRC connection setup success rate. Typically when the traffic increases the inter-cell interference also increases (caused by more users in general and more users under poor radio conditions) and therefore more failures in signalling message reception at the eNodeB and at the UE occur and performance decreases. Message 4, Contention Resolution and RRC Connection Setup Message Reception Once the eNodeB receives message 3, it prepares to send message 4, which is concatenated message including contention resolution and RRC connection setup messages, to the UE. For message 4, containing the contention resolution message, downlink grant is addressed temporary C-RNTI, allocated to the UE in random access response message, on PDCCH. The contention resolution is simply the copy of the 40 bit UE identity (allocated by the UE itself based on SAE Temporary Mobile