Offloading 4G Traffic to 3G

Hello Team,
From the recent customer complain, 4G Layer is over utilized (High PRB Utilization, High number of connected users, Poor User experience) yet the 3G Layer is not fully utilized. 3G Layer has 3 Frequencies.
Which parameters to modify to offload users from 4G to 3G?


if ericsson equipment, you can try to activated inter rat offload to WCDMA feature and tuning related parameters, i.e lbUtranOffloadThreshold.


better to refarm your 3G carrier to 4G carrier for example you can use additional 10MHz for LTE and still using 5MHz for 3G. Of course if your 3G utilization it’s no issue

Customer is not planning to add another L1800 Layer

Reduce the cell radius.

I think reducing cellradius would be a mistake.
People will stay without service after cellradius is reached.
No RACH will pass no HO will pass after cell radius if you reduce cellradius.

It’s more of strategic question than simple optimization.

You need to check reason for high PRB:

→ If it is due to higher number of users and they all have good average user throughput then it means you just have high traffic. And general solution is add more capacity without compromising user experience Moving these people to 3G by any optimization is going to get you some annoying customers.

→ if high PRB is due to too many users in bad RF conditions consuming too many resources then you need to fix your HOs to move them to better sites. Or there are other optimization options.

→ if customer has VoLTE enabled , you could potentially SRVCC/CSFB them to 3G.

This can work only if 4G band is higher frequency than 3G otherwise far end customers may suffer with low coverage.

Yes, I agree.
Need to analyse the RI & CQI parameters of the cells and no of users as well.
High PRB utilisation and low throughout may indicate poor radio conditions.

Huawei and Ericsson has “Offload to WCDMA” feature.

Does cell radius has to coincide with cellrange?
Ways of defining the cell radius are power, tilts and crsgain, right?
But do we need to define also the cellrange?

Yes cellradius is cellrange. It has to be defined according to your power, tilts, antenna height, terrain geography. Not according to one’s wishes! Because if the cell is best server at 8km away on a small piece of land and there are users at this location small piece of land and your cellradius is just 5km then those users will be without service.

To offload from 4G to 3G you can try with idle mode parameters: threshservinglow ( to send users quickly to 3G) and threshxhigh ( to force them not to comeback so easy to 4G from 3G). Similar parameters for connected mode A2 and B1 events.

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