he beginning, that is, select the preamble from preamble group and send the selected new preamble with increased power as PREAMBLE_TRANSMISSION_COUNTER is incremented by 1. The coding rate for message 4 delivery on PDSCH and CCE aggregation level for DCI transmission on PDCCH for message 4 are either fixed by parameters or adjusted by the eNodeB algorithm. Similar to random access response those parameters should be set SO that good enough RRC connection setup success rate is achieved. It should be noted that in case the UE cannot receive message 4 it cannot send message 5 and therefore from statistics point of view message 5 reception problems are detected. The RRC connection setup success rate improvement with decreased message 4 coding rate on PDSCH and increased CCE level for DCI delivery on PDCCH of one test cluster during busy hour is shown in Table 12.1. It should be noted that other parameters impacting on message 4 reception success rate that should be tuned as well are HARQ retransmission times for message 4. Related to above the contention resolution time should be long enough SO that terminal can receive all specified transmissions of message 4. For example, if 4 HARQ transmissions are allowed for message 4 then contention resolution timer should be minimum 4 X 8 ms = 32 ms. Table 12.1 Radio resource control connection setup success rate optimization depending on message 4 parameters PDSCH PDSCH PDSCH coding rate = 0.39 coding rate = 0.12 coding rate = 0.05 PDCCH CCE PDCCH CCE PDCCH CCE aggregation level = 4 aggregation level = 4 aggregation level = 8 Total number of received RRC 10,577 connection request messages (message 3) RRC connection setup success 99.41 99.96 rate (%) LTE Key Performance Indicator Optimization RRC connection setup Random access setup success rate (%) success rate (%) 200 ms 400 ms 1000 ms Figure 12.15 RRC connection setup success rate and random access setup success rate as a function of T300 T300 is started by layer 3 transmission of RRC connection request to lower layers with