– Equipement 4G Huawei
– Your Network using CSFB
– You have GL and GUL Collocated
– Your InterRat Mobility using Redirection
– L.RRC.Redirection.E2G.Coverage to High possibility UE directly Redirect to 2G while in the neighbor 3G RSCP still good for Target Redirection
Highest priority InterRat = GERAN
Second priority InterRat = UTRAN
CSFB Highest priority InterRat for Idle UE = GERAN
CSFB Second priority InterRat for Idle UE = UTRAN
In site GL (without UTRAN Collocated) When you Set CSFALLBACKBLINDHOCFG Highest priority InterRat to GERAN, actually not only make your CSFB priority to GERAN but also trigger L.RRC.Redirection.E2G.Coverage for priority, HEDEX Reference Below:
Triggering and Stopping of Blind Handling
Events A2 and A1 for blind handling trigger and stop coverage-based inter-RAT blind handling in the same procedures as they trigger and stop coverage-based inter-frequency blind handling. Coverage-based inter-frequency blind handling and inter-RAT blind handling share the same thresholds related to events A2 and A1 and have the same working principles. For details, see Intra-RAT Mobility Management in Connected Mode.
The eNodeB selects the target RAT based on the RAT priorities specified by the following parameters:
CSFallBackBlindHoCfg.InterRatHighestPri: specifies the RAT with the highest priority.
CSFallBackBlindHoCfg.InterRatSecondPri: specifies the RAT with the second-highest priority.
CSFallBackBlindHoCfg.InterRatLowestPri: specifies the RAT with the lowest priority.
MOD CSFALLBACKBLINDHOCFG:CNOPERATORID=0, InterRatHighestPri=UTRAN, InterRatSecondPri=GERAN, IdleCsfbHighestPri=UTRAN, IdleCsfbSecondPri=GERAN;
* in case SRAN 13 you should check your CELLALGOSWITCH
L.RRC.Redirection.E2G.Coverage switch out to L.RRC.Redirection.E2W.Coverage
CSFB maintain to G
Actually this optimization depend on your strategy in GL and GUL network, in this case we prefer for triggering coverage UE maintain to UMTS and for CSFB on GL Network we prefer to G