5GS Return Handover Using Stored Target Cell IDs
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Solution Overview
Problem
Current 5G systems (5GS) lack a solution for quickly returning to 5GS after handover to Evolved Packet System (EPS) due to EPS fallback from 5GS, leading to prolonged stay in EPS even after voice sessions end, which can result in suboptimal network utilization due to better coverage of EPS compared to 5GS in overlapping deployments.
Innovation Solution
Implementing a method for generating a handover request with an indication of no QoS flow for voice, selecting a serving gateway, and re-establishing a connection with the UE to 5GS after voice signal termination, using a base station to manage the handover process and include last used 5GS PLMN IDs in the handover command.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If handover to EPS is performed due to EPS fallback from 5GS, then voice service continuity is maintained, but UE remains in EPS for prolonged period after voice session ends, reducing network utilization efficiency
Solution Approach 1:
The base station stores the target cell ID of the 5GS cell before handover to EPS occurs. This preliminary storage of return path information enables rapid redirection back to 5GS after voice session termination, eliminating the need for UE to perform lengthy network searches and achieving quick return to optimize network utilization
2Productivity
If UE returns to 5GS after voice session in EPS, then network utilization is optimized, but additional handover signaling and processing are required
Solution Approach 1:
The target cell ID of the 5GS cell is stored in advance at the base station before EPS handover. When voice session ends, this pre-stored information is immediately used to construct the redirection command, significantly reducing signaling exchange and processing time compared to performing all handover parameters negotiation at that moment
Solution Approach 2:
The base station uses the previously stored target cell ID information to quickly reconstruct the handover command for returning UE to 5GS. This copying of pre-stored identification data avoids repeating complex parameter matching and cell selection procedures, simplifying the return handover process
Data Source
AI summary
Some embodiments of this disclosure include apparatuses and methods for managing a fast return of a user equipment (UE) to 5G systems (5GS) after handover to Evolved Packet System (EPS) due to EPS fallback from 5GS. The method can include at least generating a handover request including an indication indicating a handover reason of no presence of quality of service (QoS) flow for a voice signal to the UE; receiving a handover command generated by an access and mobility management function (AMF) to transfer the UE from the 5GS to the EPS based on the handover request; transmitting the handover command to the UE for the UE to establish a connection with the EPS; and after the flow of the voice signal has terminated, re-establishing a connection with the UE to reconnect the UE to the 5GS, wherein the connection with the BS is re-established based on a target ID of the BS.