Selection is based on:
if the pathloss is less than PCMAX,c (of the Serving Cell performing the RandomAccess Procedure) – preambleInitialReceivedTargetPower – deltaPreambleMsg3 – messagePowerOffsetGroupB, then:
- select the Random Access Preambles group B;
- else :
- select the Random Access Preambles group A.
PCMAX,c- maximum output power PCMAX,c of the serving cell.
preambleInitialReceivedTargetPower- taken from SIB2, Preamble initial received target power with values from -120 dBm to -90 dBm with step size of 2 dBm .
deltaPreambleMsg3 - power control related parameter .
messagePowerOffsetGroupB- Power offset for selecting preamble Group B (0, 5, 8, 10, 12, 15 or 18 dB).