EPS Fallback Timer for 5G Call Drop Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing 5G NR network faces high call drop rates due to failed connections and handovers between the 5G NR and LTE networks, primarily caused by poor signal conditions and inefficient EPS fallback mechanisms, leading to prolonged call setup times and user experience issues.
Innovation Solution
Implementing an EPS FB timer and Quality of Service (QoS) timer in the UE and server to manage handovers and bearer allocations, enabling the UE to initiate service requests or updates when EPS FB commands are not received, and performing Tracking Area Updates to ensure stable call establishment over dedicated bearers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE uses the existing preconditioning mechanism and waits for a certain time for dedicated bearer establishment, then the call setup procedure follows the standard flow, but the call drop rate becomes substantially high due to access failure and repeated return behavior
Solution Approach 1:
The patent applies preliminary action by initiating the EPS FB timer immediately when the EPS FB command is received, before the dedicated bearer establishment process completes. This allows the system to proactively detect bearer establishment failures and trigger call recovery procedures in advance, rather than waiting for the standard preconditioning mechanism timeout. The timer is set to expire before the standard call setup time, enabling early intervention to prevent call drops.
Solution Approach 2:
The patent implements feedback by continuously monitoring whether the dedicated bearer is successfully established within the EPS FB timer duration. If the bearer is not established by the time the timer expires, the system receives feedback about the failure condition and automatically triggers the call recovery mechanism by sending a service request or update message to the network, thereby improving call establishment reliability.
2Productivity
If the UE returns to the 5G NR network as part of fast return after access failure, then the return behavior can be repeated many times, but the call drop rate becomes substantially high
Solution Approach 1:
The patent applies preliminary action by detecting dedicated bearer establishment failure through the EPS FB timer expiration before the UE repeatedly returns to the 5G NR network. This early detection allows the system to intervene with a service request or update message to the network, preventing the repeated fast return behavior that leads to call drops. The preliminary detection and intervention occur before multiple failed return cycles can degrade call establishment success.
3Reliability
If SIP signaling is re-initiated as a new call setup procedure after EPS FB failure, then the call can be re-established, but the time required to re-establish the voice session/call becomes considerably high
Solution Approach 1:
The patent applies preliminary action by detecting dedicated bearer establishment failure through the EPS FB timer before the standard SIP call setup procedure is re-initiated. By setting the timer to expire before the full call setup time, the system can proactively send a service request or update message to the network to trigger bearer establishment, thereby avoiding the need to completely re-initiate SIP signaling and significantly reducing call re-establishment time while maintaining recovery capability.
4Reliability
If the IMS core supports call recovery by using additional SIP signaling procedures, then call recovery is possible, but these mechanisms may not be linked efficiently with NAS protocols, resulting in call drops
Solution Approach 1:
The patent merges the SIP signaling layer and NAS protocol layer by integrating the EPS FB timer mechanism that operates at the NAS level with the SIP call recovery procedures. The timer expiration triggers a service request or update message that simultaneously addresses both the NAS bearer establishment and the SIP call continuity, creating an efficient linked mechanism between the two protocol layers that reduces call drops without excessive complexity.
Data Source
AI summary
The present disclosure provides a method for improving call performance in a wireless network. The method includes sending an invite request to a server to initiate a Voice over New Radio (VoNR) service, where the UE is connected with a first network entity, and where the invite request comprises a media feature tag. The method includes initiating an Evolved Packet System fallback (EPS FB) service timer based on the media feature tag and a quality of service (QoS) timer and establishing a call over a second network entity using a dedicated bearer when the EPS FB command is received from the server. The call is established over the second network entity using the dedicated bearer by sending a service request to the server and/or sending an update request to the server when the EPS FB timer is expired and the EPS FB command is not received from the server.