Hello Experts.
In DL we have harq feedback from UE ack/nack.
What is the analogy in UL?
gNB doesn’t send ack nack. How does UE know if data was successfully decode or not?
New data indictor flag in the next DCI for same HARQ process
It figures it out based on whether it gets retransmission request from gNB or not.
In DL we have harq feedback ACK NACK for UE to send and then gNB knows whether it has to retransmit.
But in the UL there is no HARQ ACK NACK.
How does UE know gNB successfully decoded the uplink Data and it doesn’t need to retransmit in the UL?
We have feedback for UL packets as well where ACK/NACK is given back to UE.
In LTE we have dedicated channel as PHICH.
For NR it will be on pdcch as PHICH not there.
I have different view here for NR.
There is no Ack/Nack for UL in NR.
If I’m not wrong, it is managed smartly with NDI/RV bit in UL DCI.
If pocket didnot received property, NDI value will be not toggled for next transmision with same harq.
If UL pocket received property, NDI value will be toggled.
Still, I will validate my understanding and confirm.
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Did you figure this out ?
In the next UL DCI for the same HARQ process, NDI toggled means ACK, not toggled means NACK.
no ack nack for UL in 5g, handset checks NDI bits, if it is true, handset understand gnb decoded handset packet , if ndi:false , it makes retransmission.