Will UE Transmit the scheduling request (SR) for every PUSCH?

RAN
1

Hello Experts.

Will UE Transmit the scheduling request (SR) for every PUSCH?

2

There is a timer to transmit SR.

5 or 10 msec.

3

Thanks, correct.

But my doubt is:
Is SR required before every PUSCH?
Is there any case where UE will transmit PUSCH without SR?

4

SR is required to get UL grants.

5

To my understanding SR is sent initially for first UL data then it will be used BSR buffer status report.

So eNodeB will allocate UL grants based on BSR.

6

Seems logical.

7

SR is a physical layer to request one time UL grants.

If UE need large amount of UL grants to send big chunk of data then MAC CE BSR needed.

8

It’s not like SR is required before every PUSCH channel.

SR is sent by UE whenever UE is in connected state but do not have UL resources i.e. PUSCH.
SR config is sent to UE in setup or reconfiguration message.
From where UE will cal on what SFN and SF, it has to send SR whenever requesting UL resources

Ideally, UE gets UL resources related info inside DCI0, basee upon which UE sends PUSCH channel.

Hope this clarifies your doubt.

Regarding BSR, it is a MAC CE, and MAC CE’s can be sent over DL-SCH or UL-SCH only.
So the time when UE do not have PUSCH resources, it can not send BSR, therefore UE first sends SR based upon which it gets PUSCH resources and then UE sends BSR on that PUSCH.

9

Yes, with Configured Grant there is no need for SR.