Voice Service Continuity in LTE to 2G Handover via Gs Interface
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The deployment of Evolved UTRAN (eUTRAN) and Evolved Packet Core (EPC) in multimedia mobile networks requires migrating telephony services from a traditional circuit-switched system to a packet-switched system, but this transition can lead to voice service disruptions due to the lack of initial IMS service deployment, causing voice calls to be dropped when users leave LTE coverage areas without a domain transfer function.
Innovation Solution
A mobility management entity identifies voice service requirements and performs handovers from packet-switched eUTRAN cells to circuit-switched GERAN/UTRAN cells, allowing voice service establishment in the CS domain, leveraging existing 2G/3G infrastructure to maintain continuous service.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If telephony services are migrated from circuit-switched to packet-switched system, then network modernization and cost efficiency are improved, but voice service continuity deteriorates when users leave LTE coverage areas
Solution Approach 1:
The patent introduces an intermediary mechanism (domain transfer function and handover protocol) that enables seamless transition between packet-switched and circuit-switched domains. This intermediary layer allows the network to maintain voice service continuity by mediating between the modern eUTRAN/EPC packet-switched infrastructure and the legacy GERAN/UTRAN circuit-switched network, resolving the contradiction between network modernization and service reliability.
Solution Approach 2:
The system performs preliminary actions by pre-establishing domain transfer capabilities and handover protocols before voice service disruptions occur. The mobility management entity is pre-configured to recognize voice service requirements and initiate handover procedures to circuit-switched cells proactively, preventing call drops rather than reacting to them after they occur.
2Device complexity
If IMS service deployment is delayed, then deployment costs and complexity are reduced, but voice service reliability deteriorates in packet-switched networks
Solution Approach 1:
The patent enables the network to serve itself by allowing the mobility management entity to autonomously identify voice service requirements and trigger handovers to circuit-switched cells without requiring IMS service deployment. The system uses self-service mechanisms to maintain voice reliability through existing 2G/3G infrastructure, eliminating the need for complex IMS deployment while preserving service quality.
3Reliability
If handover to circuit-switched cells is implemented, then voice service continuity is improved, but network infrastructure complexity increases
Solution Approach 1:
The patent applies universality by designing the handover mechanism to work with existing multi-functional 2G/3G network infrastructure that already supports both circuit-switched and packet-switched operations. The mobility management entity leverages the universal capability of legacy cells to provide voice services, avoiding the need for dedicated new infrastructure and minimizing overall system complexity while ensuring voice continuity.
Data Source
AI summary
User Equipment (UE) receiving non-voice packet switched service in an Evolved Universal Mobile Telecommunications System Terrestial Radio Access Network (eUTRAN) cell undergoes handover to a circuit switched GSM/Edge Radio Access Network (GERAN)/UTRAN cell in response to a requirement for voice service. The voice service is established in the circuit switched domain of a GERAN/UTRAN cell to ensure service continuity regardless of UE mobility that would otherwise not be possible if the voice service was established in the eUTRAN cell. A Gs-like interface between a Mobile Switching Center (MSC) of the CS Core Network and the Mobility Management Entity (MME) of the Evolved Packet Core provides an interface for page requests and location update procedures to be performed.