UE not following reselection priorities

Hello Experts,
Anyone faced issue with handsets not following reselection priorities and always camping on higher frequency layer (which has low BW)?

  1. From UMTS to LTE Fastreturn on L900
  2. No reselection from L900 to L1800 despite L1800 has higher reselection priority and good coverage.

At the same location other hansdsets follow priorities and camp on L1800.
Vendor is Huawei.
Kindly comment.

Does that handset support L1800?

Yes, sometimes it camps on L1800.

Check TheshXHigh from 900 to 1800.
If very high value make it relax.

Check also Treselection, not just Threshx-high.
All should be in SIB5.

L1800 to 900:

L900 to 1800:

L900 (priority 6) to L1800 (priority 7) UE moves to higher priority if nrb cell is better than -114dBm (hys 4dB and 1s).
RSRP Target > QRxLevMin(-60) + ThreshXhigh(3). L1800 RSRP is way better than this but still doesn’t re select.

What is the value of sNonIntraSearch of L1800?

sNonIntraSearch = 4 dB.

What you have here is L900 to L1800 threshXhigh=6dB with prio7; also L1800 to L900 Threshxlow=10 dB prio6.
It is only 4 dB delta you may have pingpong in reselections.
You may want to increase this delta to 8 dB like this: L900 to L1800 threshXhigh=4dB with prio7; also L1800 to L900 Threshxlow=12 dB prio6.

Do you mean this setting but for higher to lower layer do we need to change source measurements? CellResel.SNonIntraSearch and CellResel.ThrshServLow.


There are also conditions for serving cells in case of moving to lower prio cells.


To reselect to lower priority RSRP should be less than sNonIntraSearch.
Which is not case here, as L1800 RSRP is better.
If RSRP quite good, then no ping pong issue suspected here.

I think RSRP has to be lower than threshservinglow to start checking criteria for lower prio reselection.

Both sNonIntrasearch and threshservinglow need to satisfy.
Generally they are kept equal.

What’s the value of L1800 threshservinglow in SIB3?
What’s the value of L1800 s-nonintrasearch in SIB3?

L1800 to L900 snonintra low value and L900 to L1800 snonintra high value to start measurement.
L1800 to L900 thresxlow high value and L900 to L1800 threshxhigh low value.

This is current scenario for L1800 to L900.
But point is signal level is better than -114 dBm.
It reselects to L900 even on -80 dBm.

It will reselect after measurement of minus 116.
Measurements will start at minus 116 to interfreq.
And reselect better than minus 110.
Discard hyst and offset for a moment.
Threshxlow make high.
For late reselection.
Make 5 to 9 or 10.
But will be aggressive.
As reselection will go less to L900.

Reselection to low priority inter freq:

  1. Snonintrasearch
  2. threshserving low for serving
  3. Neighbor must be better then interfreqthreshlow

threshservinglow 0dB is for L1800?