Voice Handover Control in 5G to 3G SRVCC Systems
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Solution Overview
Problem
In the context of 5G to 3G single radio voice call continuity (SRVCC), there is a need for a method to control the radio access technology (RAT) and public land mobile network (PLMN) access for user equipment (UE) after a voice call is completed, as existing systems lack parameters related to the 5G network and SRVCC is only applicable in connected mode mobility.
Innovation Solution
A method involving a user equipment (UE) connected to a 5G network, which receives control information from a base station (BS) of a 3G network to determine the appropriate RAT and PLMN to use after a voice call, allowing seamless handover and prioritization of networks, using control information that includes subscriber profile IDs and PLMN IDs, even in connection mode mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SRVCC handover is performed from 5G to 3G network, then voice call continuity is maintained, but control information for RAT and PLMN selection after call completion cannot be transmitted
Solution Approach 1:
The network side performs preliminary actions by determining the RAT and PLMN that the UE should use after voice call completion, and includes this control information in the handover command message transmitted during SRVCC handover. This allows the UE to be pre-configured with network selection preferences before the handover is completed.
Solution Approach 2:
The handover command message acts as an intermediary carrier to transmit control information from the network side to the UE. By embedding the RAT and PLMN selection control information within this existing message structure, the patent enables information transmission without requiring separate signaling channels.
2Adaptability or versatility
If control information is transmitted during connected mode mobility, then RAT and PLMN selection is enabled, but existing 3G network parameters and standards must be modified
Solution Approach 1:
The handover command message is made multi-functional by enabling it to carry both the traditional handover control information and the additional RAT/PLMN selection control information. This universal approach allows existing message structures to serve multiple purposes without requiring separate dedicated messages.
Solution Approach 2:
The patent introduces new parameters (RAT selection control information and PLMN selection control information) into the existing handover command message framework. These parameter additions enable enhanced functionality while maintaining compatibility with the existing 3G network structure through controlled parameter extensions.
3Ease of operation
If RFSP index or SPID is delivered to UE in idle mode mobility, then network selection priority is provided, but these parameters cannot be transmitted in connected mode mobility
Solution Approach 1:
Instead of delivering control information during idle mode mobility as in conventional approaches, the patent inverts the timing by transmitting RAT and PLMN selection control information during connected mode mobility through the handover command message. This reversal enables network selection priority to be established before the UE transitions to idle mode.
Data Source
AI summary
The present disclosure relates to a 5G or pre-5G communication system for supporting higher data transmission rates than 4G communication systems such as LTE. The present invention relates to a method and device for supporting voice handover in a wireless communication system and increasing service quality in a mobile communication system, and more specifically, to a method for a UE connected to a first network to communicate with a network in a wireless communication system, the method comprising the steps of: connecting a voice call to a second network; receiving, from a base station of the second network, a message including control information for controlling wireless access of the UE; and using the control information to determine the radio access technology (RAT) to be used and the PLMN to be accessed after the voice call is completed, wherein the first network and the second network communicate using different RATs, and the voice call is connected to the second network by circuit switching (CS).