Mobile Device CSFB Call Setup Time Reduction
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Solution Overview
Problem
The existing technologies face delays in processing Circuit-Switched Fallback (CSFB) calls due to unsuccessful attach procedures in Packet-Switched networks, leading to prolonged call setup times during Tracking Area Updating procedures.
Innovation Solution
The mobile communication device selects an alternative network capable of providing Circuit-Switched services upon receiving a rejection message with specific cause values, thereby bypassing the need for re-attachment to the initial PS-only network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE performs the attach procedure with the LTE network after receiving TRACKING AREA UPDATE REJECT message, then the UE can potentially re-establish PS services, but the CSFB call setup time is significantly prolonged due to multiple retry attempts and guard periods
Solution Approach 1:
The patent applies preliminary action by checking whether a CSFB-related call is pending before executing the attach procedure after receiving TRACKING AREA UPDATE REJECT message. If a CSFB call is pending, the UE proactively selects an alternative network capable of providing CS services immediately, rather than waiting to complete the attach procedure first. This preliminary check and conditional network selection prevents time wastage while preserving the ability to re-establish PS services when needed.
2Reliability
If the UE waits for the attach procedure to complete before processing CSFB call requests, then the attach procedure can be completed properly, but the CSFB call processing is seriously delayed
Solution Approach 1:
The patent applies dynamics by making the network selection behavior adaptive based on the calling state. The UE dynamically adjusts its network selection strategy: if a CSFB-related call is pending when TRACKING AREA UPDATE REJECT is received, the UE immediately selects an alternative network for CS services; otherwise, it proceeds with the attach procedure. This dynamic decision-making allows the system to optimize between attach completion and call processing speed based on real-time conditions.
3Reliability
If the UE retries the attach procedure multiple times with guard periods, then the PS service can be re-established, but the overall time consumption increases significantly
Solution Approach 1:
The patent applies preliminary action by checking whether a CSFB-related call is pending before executing the attach procedure after receiving TRACKING AREA UPDATE REJECT message. If a CSFB call is pending, the UE proactively selects an alternative network capable of providing CS services immediately, rather than waiting to complete the attach procedure first. This preliminary check and conditional network selection prevents time wastage while preserving the ability to re-establish PS services when needed.
Data Source
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AI summary
A mobile communication device including a wireless transceiver and a controller is provided. The wireless transceiver performs wireless transmission and reception to and from a first network supporting only Packet-Switched (PS) services or a second network supporting Circuit-Switched (CS) services. The controller receives a rejection message of a Tracking Area Updating (TAU) procedure from the first network via the wireless transceiver when a Circuit Switch Fallback (CSFB) -related call originated from or terminated to the mobile communication device is pending, determines whether the rejection message includes a predetermined rejection cause, and in response to the rejection message including the predetermined rejection cause, selects the second network to make the CSFB-related call via the wireless transceiver without re-attaching to the first network.