Mobility Management Entity Circuit Switched Fallback
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Solution Overview
Problem
Current cellular communication systems face challenges in efficiently interworking different radio access networks to provide circuit switched services while supporting both packet and circuit switched services, leading to increased call setup times and complexity, especially when transitioning between E-UTRAN and UTRAN/GERAN networks without IMS functionality.
Innovation Solution
A cellular communication system that includes a core network, a packet switched first radio access network, a packet switched and circuit switched second radio access network, and a mobility management entity, where user equipment detects the initiation of a circuit switched application and initiates an access network reselection from the first to the second network, allowing the mobility management entity to update routing associations, thereby reducing call setup delays and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a user equipment camped on E-UTRAN switches to UTRAN/GERAN to set up a circuit switched call, then circuit switched services can be provided using existing infrastructure, but call setup time increases due to network routing updates
Solution Approach 1:
The system performs preliminary routing association updates at the mobility management entity before the actual handover is completed. When a user equipment initiates a circuit switched call from E-UTRAN, the network proactively updates routing associations in advance, so that when the handover to UTRAN/GERAN occurs, the routing is already optimized, reducing overall call setup time
Solution Approach 2:
The mobility management entity acts as an intermediary between the radio access networks and the core network elements. It maintains routing associations that map user equipment to appropriate radio access networks, and proactively updates these associations during handover to minimize disruption and reduce call setup time
2Adaptability or versatility
If the system maintains routing associations for user equipment across multiple radio access networks, then network flexibility is improved, but system complexity increases
Solution Approach 1:
The mobility management entity serves as a centralized intermediary that manages all routing associations between user equipment and radio access networks. It maintains a mapping of user equipment identities to current radio access network locations, and automatically updates these associations during handovers, shielding the rest of the network from complexity while maintaining flexibility
Solution Approach 2:
The mobility management entity performs multiple functions: it manages routing associations for both packet switched and circuit switched services, handles handovers between different radio access network types, and maintains user equipment location information. This multi-functionality consolidates complexity into a single entity while providing universal routing support
3Productivity
If the mobility management entity proactively updates routing associations during handover, then call setup efficiency is improved, but signaling overhead increases
Solution Approach 1:
The mobility management entity performs routing association updates as a preliminary action triggered by the handover initiation itself, rather than waiting for separate call setup procedures. This proactive update, triggered by existing handover signaling, improves call setup efficiency while minimizing additional signaling overhead by reusing the handover signaling pathway
Data Source
AI summary
A cellular communication system comprises a core network, a first access network not supporting circuit switched services and a second access network supporting circuit switched services. A user equipment detects that an application using circuit switched communication is initiated and accordingly initiates a reselection from the first to the second access network. The user equipment transmits a location update message to a circuit switch mobile switching center of the core network which in response notifies a mobility management entity for the first access network that the access network reselection has been initiated. In response to the notification the mobility management entity initiates a change of a routing association from being with the first access network to being with the second access network. The invention may e.g. allow improved circuit switched fallback for a 3rd Generation Partnership Project cellular communication system comprising an access network supporting only packet switched services.