KPIs Affecting CSFB and Fast Return Success Rate

4G LTE
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What are the KPIs that affect the success rate of CSFB and Fast Return to LTE?

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Evidence Intake Perspective

CSFB (Circuit Switched Fallback) and Fast Return to LTE (FRLTE / IRAT Return) success rates are not driven by a single KPI. They are composite behaviors affected by:

  • LTE accessibility and mobility KPIs

  • CS domain accessibility KPIs (2G/3G)

  • Inter-RAT signaling health

  • Paging and redirection performance

  • UE capability/vendor behavior

  • Core network latency and congestion

CSFB itself is standardized within EPS mobility and voice domain procedures in EPC architecture.

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CSFB can happen in 2 methods one is vis ESR( Extendard Service request in S1 interface) and second is SIP 380 Alternate services from IMS.But Neither IMS or EPC or even MSC has no control or no trigger for mobile for a fast return.Fast return is totally depend on RAN config and Next mobility event of the subscriber.

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