Sudden variations in DL Throughput

Hi Dears,
I have the following case: in 4G the UL have always about 26 Mbps, is correct.
In DL some time 30 Mbps, but another time 3 Mbps. Always have very different values.
RSRP -89 dBm SINR 8 dB
What can be possible cause and solutions?
Vendor is ZTE.

image image

It is better if you test with TEMS Pocket or another device and do ftp DL/UL to Speedtest Server.
I don’t like to use this tool…

Couple things to check:
What is the rank, and what is the expected MIMO config for the site?
Check the number of DL PRBs being allocated to UE.
For 20 MHz it should be 100 PRBs and UE should receive > 90 PRBs for Peak Throughput.
If you see less PRBs, then site is congested.
Check Downlink BLER.

User in site, in blue color sector with problems.

PRB Usage:

In Walk Test, PRB 100%:





Throughput DL always down:


Throughput FTP agree with Speed Test.

Throughput UL is agree that FTP UL:

MIMO is only 2x2:


This looks like a Configuration issue rather RAN issue, as difference is too large.
Have you checked UE profile in SGW/PGW or HSS profile for maximum DL per APN?

UE profile is not because the problem is in all UE in coverage of this sector.

You have 150 avg user per cell, thats a lot!
Is that active connected users?

RRC connected users.
Active users is less.

This is congestion problem then.
Your SINR is bad even in good RSRP but that is possibly due to too many users.
20 MHz with 2x2 MIMO and 64QAM has max throughput of 150 Mbps.
150 users active is avg 1 Mbps per user.
You may want to reduce your cell load.
Lower inactivity timer and see if that helps.

1 Like

Yes, correct, I’ll try. Thanks.
And I will also change tilt for reduce coverage.


I think you should also check Transmission capacity & configuration. Verify MAX PDCP DL / UL Throughput in order to check if there is any kind of limitation on the Transmission path.


Hola Jorge!
There are a couple of things I’ll check:
1- Are both UE camped in the same cell/carrier?
2- From the stats you share seems that you have a congestion issue in that cell, so check if the user profile on both phones are the same. It happened to me that for an unknown reason one phone was having an HBB profile while another had a mobility unlimited offer which ends up in congested sites with very different THP between both.
3- Carrier aggregation is the same for both UE’s?

Probably there are more reasons, but those are the ones that pop in my mind now. Cheers! Diego

1 Like