Information in DCI that indicates if the scheduled PDSCH is Old or New

[TelecomLover]

Hi Experts.

When UE doesn’t decode PDSCH correctly it sends a NACK.

Then gNB sends DCI again for scheduling a retransmit.

Does anyone know if there is an information in DCI that indicates if the PDSCH scheduled is Old or New?

Admin note: this post was updated with image below.

[C_j]

NDI bit toggled if new tx.

[TelecomLover]

Is that for both UL and DL?

[C_j]

Yes, for both.

[Nitin]

@TelecomLover

Does anyone know if there is an information in DCI that indicates if the PDSCH scheduled is Old or New?

Yes. RV - Redundancy Version

@C_j

NDI bit toggled if new tx.

I think this one is for PUSCH.

[TelecomLover]

@Nitin

I think this one is for PUSCH.

That’s my understanding as well…

@Nitin

RV - Redundancy Version

How exactly?

[Nitin]

@TelecomLover

How exactly?

This is a field in DCI.

I think it’s sent like 0 2 1 3

0 for tx

Rest for retx

[TelecomLover]

So through this field UE can know if PDSCH is new or no?

[Nitin]

Yup, correct.

[C_j]

@C_j

NDI bit toggled if new tx.

[Nitin]

@C_j

Makes sense…
Because 4 RV values and up to 8 TX possible.

[C_j]

@Nitin

Makes sense…
Because 4 RV values and up to 8 TX possible.

Infact 16 in 5G.

[TelecomLover]

@C_j

So it’s both NDI and RV?

[C_j]

Yes, correct.

[gkreddy]

@C_j

Infact 16 in 5G.

What does 16 indicate here?

[susbose10]

@gkreddy

What does 16 indicate here?

I think he’s mentioning HARQ process.