Centralized Gateway Circuit Switch Fallback Latency Reduction
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Solution Overview
Problem
The existing solutions for Circuit Switch Fallback (CSFB) operations in mobile communication networks, such as MSC upgrading and virtual MSC methods, are costly and introduce significant delays in call setup times, making them unviable for widespread implementation.
Innovation Solution
Centralizing CSFB functionality through a centralized gateway that registers mobile devices with both LTE and CS networks using LTE and CS protocols, allowing pre-registration and minimizing delays by informing mobile devices to switch to the CS network before call establishment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MSC upgrading is performed to support CSFB operations, then voice service compatibility is improved, but implementation cost increases significantly
Solution Approach 1:
The patent segments the CSFB support functionality from the MSC by introducing a separate SGs interface and associated network elements (MME, HSS) that can provide CSFB operations independently of MSC upgrades. This allows CSFB capability to be implemented in the LTE core network without modifying legacy MSC equipment, thereby reducing implementation costs while maintaining voice service compatibility.
Solution Approach 2:
The patent introduces an intermediary mechanism (the SGs interface and associated signaling procedures) that enables communication and coordination between the LTE network (MME) and the CS network (MSC/VLR) without requiring direct integration or upgrades to the MSC. This intermediary approach allows CSFB operations to function while avoiding the high costs of MSC upgrading.
2Ease of manufacture
If virtual MSC method is used for CSFB operations, then deployment cost is reduced, but call setup time increases significantly
Solution Approach 1:
The patent implements preliminary registration and authentication procedures through the SGs interface before actual CSFB calls are initiated. The mobile device and network establish registration status and exchange necessary signaling information in advance, so that when a CSFB call is needed, the setup time is minimized because the preliminary work has already been completed. This reduces call setup time while maintaining the cost benefits of the virtual MSC approach.
Solution Approach 2:
The patent implements feedback mechanisms where the network and mobile device exchange signaling information to confirm registration status, network capabilities, and call setup readiness. This feedback loop ensures that both sides are synchronized and prepared for rapid CSFB operations, reducing unnecessary delays in call setup while maintaining deployment cost efficiency.
3Productivity
If mobile device defaults to LTE network, then data communication efficiency is improved, but voice service switching delay increases
Solution Approach 1:
The patent enables mobile devices to perform preliminary registration with both LTE and CS networks simultaneously through the SGs interface. This preliminary action allows the device to maintain readiness for both data (LTE) and voice (CS) services without needing to switch networks when a voice call is initiated. The device can default to LTE for data communication while having pre-established connectivity options for voice, thereby reducing switching delay.
Solution Approach 2:
The patent implements a universal registration mechanism where the mobile device registers with the LTE network while the network maintains awareness of and connectivity to the CS network through the SGs interface. This multi-functionality allows the device to operate primarily on LTE for data communication while seamlessly accessing CS network services when needed, eliminating the need for manual or delayed network switching.
Data Source
AI summary
Systems and methods herein utilize interworking protocols with centralized functionality to perform CSFB with minimal latency for an inbound and/or outbound communication with a mobile device that is attached to a communication network not operable to service the communication. Embodiments utilize a centralized gateway that communicates in both an LTE network and CS network. In embodiments, the mobile device may be concurrently attached to the LTE network, registered with the centralized gateway, and registered with an MSC of the CS network. Upon the CS network receiving an inbound call for the mobile device or upon the mobile device originating a call, the MSC may set up the call with the mobile device with minimal latency because the mobile device is pre-registered with the MSC.