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Member
Reputation: 44
Query about UMTS Open Loop Power Control Paramter: "PowerOffsetPpm"
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
Last edited by Osman Nayeem; 2012-12-06 at 08:09 PM
Reason: to edit line break
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2012-12-06 08:06 PM
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Member
Reputation: 295
Re: Query about UMTS Open Loop Power Control Paramter: "PowerOffsetPpm"
Originally Posted by
Osman Nayeem
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
Hi! Check the thread below.
http://www.finetopix.com/showthread....ntrol-question
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