Osman Nayeem
2012-12-06, 08:06 PM
Dear Experts,
Following is the formula to calculate initial preamble power for UMTS outer loop power control:
P_RACH(Preamble_Initial_Power) = PCPICHPower - CPICH_RSCP + RTWP + constantValueCprach
For a particular moment, lets say, CPICH_RSCP= -67dBm, RTWP = -100dBm, PCPICHPower = 33dBm & Constantvalue = -27(e******* default), which gives, P_RACH = -27dBm
Lets say, last submitted preamble power is -20dBm when UE receives a positive acquisition indicator. Next we have to calculate RACH transmitting power, RACH Transmitting power = last submitted preamble power + "PowerOffsetPpm"
As per my understanding, RACH transmitting power should be equal to or greater than -20dBm(last submitted preamble power), which means "PowerOffsetPpm" should be equal to or greater than zero.
Question: My confusion is, E******* recommended value for PowerOffsetPpm is -4dBm (negative offset !!). Huawei is also used a negative offset for this parameter. Can anyone please explain why?
Thanks,
Osman Nayeem
Following is the formula to calculate initial preamble power for UMTS outer loop power control:
P_RACH(Preamble_Initial_Power) = PCPICHPower - CPICH_RSCP + RTWP + constantValueCprach
For a particular moment, lets say, CPICH_RSCP= -67dBm, RTWP = -100dBm, PCPICHPower = 33dBm & Constantvalue = -27(e******* default), which gives, P_RACH = -27dBm
Lets say, last submitted preamble power is -20dBm when UE receives a positive acquisition indicator. Next we have to calculate RACH transmitting power, RACH Transmitting power = last submitted preamble power + "PowerOffsetPpm"
As per my understanding, RACH transmitting power should be equal to or greater than -20dBm(last submitted preamble power), which means "PowerOffsetPpm" should be equal to or greater than zero.
Question: My confusion is, E******* recommended value for PowerOffsetPpm is -4dBm (negative offset !!). Huawei is also used a negative offset for this parameter. Can anyone please explain why?
Thanks,
Osman Nayeem