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What will be the MSG3 if RACH triggered to get an UL grant alone?

+1 vote

If no SR is configured at UE side, then IF UE triggeres RACH then what will be the MSG3 content? How ENB knows UE is triggering an RACH for UL grant?

posted May 21, 2019 by Jaganathan

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3 Answers

0 votes
Best answer

In this case msg-3 would be MAC-CRNTI with/without data
And, msg-4 would be pdcch scrambled with CRNTI (as contention resolution)

answer Apr 18, 2022 by Manje Gowda K.r.
0 votes


eNB gets to know from Establishment Cause , which means that why UE need to connect to network.

answer May 22, 2019 by Sushant Bose
This is normal data transmission and already in connected mode. Why UE sends establishment cause in connected mode?
Hi, let me understand  your problem
"If UE is in connected mode, how eNB knows that UE has initiated RACH for UL Grant ?
Yeah my problem is same. UE is in connected mode but SR is not configured. (SR configuration is not mandatory in connected mode).
If UE has uplink data then UE does RACH in connected mode to get an Grant. But what UE sends in MSG3 is my question?
0 votes

If UE is in connected mode why it will go for RACH ? if it has to ask for grant it will ask in PUCCH resources right ?

answer May 24, 2019 by Sushant Bose
I have multiple question here :
1. UE is in Connected mode, does that mean RRC connected or EPC connected ?
2. If it is in RRC connected mode, then UE will have SR(PUCCH), it can ask for grant.
3. If UE is in EPC connected mode, it means that UE is in RRC Idle state and it can ask for grant.

May be better expert can comment here.