LTE inter-RAT Mobility

[brochdi]

Dear Experts,

Our Strategy of CSFB is to redirect voice calls to 2G (2G has the highest priorit : CSFallBackBlindHoCfg.InterRatHighestPri (http://127.0.0.1:7890/pages/GED0304A/11/GED0304A/11/resources/EN/LTE_FDD/eNodeB/Para/MML/ratL/para/CSFallBackBlindHoCfg-InterRatHighestPri.html)=GERAN and CSFallBackBlindHoCfg.InterRatSecondPri (http://127.0.0.1:7890/pages/GED0304A/11/GED0304A/11/resources/EN/LTE_FDD/eNodeB/Para/MML/ratL/para/CSFallBackBlindHoCfg-InterRatSecondPri.html) = UTRAN). is it true that PS redirection will follow the same strategy as CSFB? i mean that when 4G signal become low, in this case does the PS UE will be redirected to 2G (same as CSFB strategy)?
if it's true, is there any method to redirect PS users to 3G (for PS services, 3G has the highest Priority).

Thanks.

[sade]

Hi,

CSFB is triggered with User behaviour (starting phone call or receiveing a paging) - so it happens independently of radio conditions of the source LTE Cell.

PS inter-rat mobility will be triggered by poor LTE radio conditions:

In Idle:
UE will perform reselection based on abolsute priority. If UTRAN has higher priority than GERAN - it will reselect to UTRAN, if GERAN has higher priority - it will reselect to GERAN. Parameters involved:
GERANNFREQGROUP\CellReselPriority - for GERAN Absolute priority
UTRANNFREQ\CellReselPriority - for UTRAN Absolute priority

(http://localhost:7890/pages/GEE01221/08/GEE01221/08/resources/EN/LTE_FDD/eNodeB/Para/MML/ratL/para/GeranNfreqGroup-CellReselPriority.html)In Connected:
Here I am actually a little surprised, beacuse based on the documentation it really seems that parameters you mention configure priority for both CS Fallback and Coverage handover:
"Similar to CSFB blind handling, the RAT priorities for blind handovers are specified by the following parameters:
CSFallBackBlindHoCfg.InterRatHighestPri (http://localhost:7890/pages/GEE01221/08/GEE01221/08/resources/EN/LTE_FDD/eNodeB/Para/MML/ratL/para/CSFallBackBlindHoCfg-InterRatHighestPri.html)
..

CSFallBackBlindHoCfg.InterRatLowestPri" (http://localhost:7890/pages/GEE01221/08/GEE01221/08/resources/EN/LTE_FDD/eNodeB/Para/MML/ratL/para/CSFallBackBlindHoCfg-InterRatLowestPri.html)


In seems obvious that it should be possible to make CSFB to GSM and Coverage PS Handover/Redirection to UMTS. I found following settings:
"The coverage-based handover from E-UTRAN to GERAN is enabled or disabled by the switch GeranRedirectSwitch or GeranPsHoSwitch under the ENodeBAlgoSwitch.HoModeSwitch (http://localhost:7890/pages/GEE01221/08/GEE01221/08/resources/EN/LTE_FDD/eNodeB/Para/MML/ratL/para/ENodeBAlgoSwitch-HoModeSwitch.html) parameter."
So, if you disable those switches, eNodeb will select second priority target which sould be UTRAN.

Anyway, you can check current situation with counters:
L.IRATHO.E2G.ExecSuccOut (http://localhost:7890/pages/31188201/11/31188201/11/resources/hert/mbts/perf/ratL/enodeb/b-enodeb-perf/Mt-1526726994.html)
L.IRATHO.E2W.ExecSuccOut (http://localhost:7890/pages/31188201/11/31188201/11/resources/hert/mbts/perf/ratL/enodeb/b-enodeb-perf/Mt-1526726991.html)

L.RRCRedirection.E2G (http://localhost:7890/pages/31188201/11/31188201/11/resources/hert/mbts/perf/ratL/enodeb/b-enodeb-perf/Mt-1526728326.html)
L.RRCRedirection.E2W

(http://localhost:7890/pages/31188201/11/31188201/11/resources/hert/mbts/perf/ratL/enodeb/b-enodeb-perf/Mt-1526728326.html)Check them out and let me know for which ones do you have values and which one are 0s - I'm curious

[fekeme]

@sade, in addition to your suggestion one should note that in order to enable UTRAN PS Handover the UtranPsHoSwitch parameter under ENodeBAlgoSwitch must be enabled if the RNC and MME both support "PS_HO". Otherwise UtranRedirectSwitch must be enabled for UTRAN Redirection.

CSFB and PS Handover (Redirection) are different procedures; both can be arranged towards different RATs.

[jenriqp]

Hi all,

You should check these parameters:
1.- UtranPsHoSwitch
2.- INTERRATPOLICYCFGGROUP ----> UTRANHOCFG=PS_HO-1 (enabled)
3.- INTERRATHOUTRANGROUP:LOCALCELLID=2, INTERRATHOUTRANGROUPID=1, INTERRATHOUTRANB1THDECN0=-24, INTERRATHOUTRANB1THDRSCP=-97 (values are examples)
4.- MOD INTERRATHOCOMMGROUP:LOCALCELLID=2, INTERRATHOCOMMGROUPID=1, INTERRATHOA1THDRSRP=-111, INTERRATHOA2THDRSRP=-115; (values are examples) .

I think, all here are waiting for your feedback @brochdi



BR (http://www.finetopix.com/member.php/112156-brochdi)