Is HARQ retransmission adaptive or non-adaptive in LTE DL?

Hi All,
Is HARQ retransmission adaptive or non-adaptive in LTE DL?
I know that it is asynchronous.

DL is always adaptive.

Also: in the UL LTE although it is synchronous HARQ retransmission does the eNB take a call whether its going to be adaptive or non-adaptive or is it always non-adaptive?

When DCI is there with HICH is there it’s adaptive, otherwise non adaptive only HICH.

Okay, so perhaps eNB takes the control here and doesn’t take any chance of signalling conditions of the UE.
So it keeps DL HARQ as always adaptive.
Is this understanding correct?

Yes, eNodeB takes control, resource allocation is deceided by eNodeB.
If UL BLER is high mg factor values shoud not be less.

So it means the UE has to always read the presence or absence of DCI to decide so?

Yes, ng factor.

Also, one more thing since UL is synchronous so UE doesn’t need to communicate the HARQ process id right?
Then how the situation is taken care when using spatial multiplexing?

eNodeB is the decision maker. :wink:

It’s beautifully explained here by @Tech_Playon:

1 Like

Yes very nicely explained with details.