Initial ramp-up time expected before UE achieves peak throughput

Hi All.

In 4G LTE, is there any initial ramp-up time expected before UE achieves peak throughput?

Or should it achieve peak throughput immediately after starting test?


There steps and dB defined, not necessarily time.

UE is informed to ramp up in steps until max power reached.

To clarify, actually I was talking of Peak throughput and not the Max Tx Power.

But this is fast it should not be more than 500 msec.

Max throughput should come within 1 sec.

Not more than 1 sec.

Otherwise ue is starving from higher layers.

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In my case I see the UE is taking 30-40s to reach the peak throughput.

Any suggestion as to what can be checked here?

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Check with sgw/pgw engineers.

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Do you mean after connecting with network?

Ok, thanks for the suggestion. I was wondering if anything could be checked on RAN side for this.

Yes, network is already ensured connected before starting the test.

It is after the throughput test is started on the UE.

What is link between UE’s power ramp up and reaching peak throughput?

UE power ramp up happens during initial access, isn’t it?

The more power in Uplink the more PRBs can be used in end of coverage.


From the question I assumed it was related to initial attach phase since those ramp up parameters only apply to initial access, no?

Once UE is in connected mode power is changed instantly at MAC layer.

Which is why I wasn’t sure of link between ramp up and peak throughput…

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Just a thought, eNB adjusts the Tx power of UE in ramp up steps based on it’s “hearing” ability of that UE in UL. So I don’t think it will impact anything in DL Tput.
Experts can correct me, if wrong.

By ramp-up I mean the time Tput test is started in UE and the time it achieves the full peak expected throughput.

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Ok that’s different then.

Ramp up in throughput has many variables for instance PRBs, MCS, multiple threads application server supports etc.

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But 30-40 seconds is a lot, core engineers may provide a hint.

It was not mentioned in initial post: is it an issue with UL or with DL throughput?

Yes, correct.

DL Throughput.

Either way 30-40 seconds is a lot.

We had major arguments for 8 seconds delay in throughput ramp up.

It should come max with 1 second.

If all is good except radio.

Is it possible site is just busy?

Really? Think max initial MCS you can set in Huawei is 16QAM.
Once the link stabilizes MCS changes.
Can that happen within a second? :thinking:

But then it would not slowly ramp up.

Sharing the Throughput graph for reference.

Here, one can see there is 16s delay while achieving peak Throughput.

But, worst case reported is 40s now.