CSFB Call Processing to Cancel Repeated ESR Retransmissions
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Solution Overview
Problem
User Equipment (UE) repeatedly transmits Extended Service Request (ESR) messages during Circuit Switched Fallback (CSFB) call establishment, leading to multiple falls back to the CS domain, disrupting normal use of LTE services.
Innovation Solution
Implement a call processing method that determines conditions for canceling ESR message retransmission, such as flag bits or radio access technology (RAT) changes, to prevent repeated CS domain falls back during CSFB calls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE repeatedly transmits ESR messages during CSFB call establishment, then the call establishment process continues, but the UE falls back to the CS domain multiple times, disrupting normal LTE service usage
Solution Approach 1:
The patent applies preliminary action by checking whether the CSFB call establishing process is suspended before transmitting the ESR message. The terminal determines the current communication state of the CSFB call and identifies suspension conditions (such as tracking area update suspension) in advance. If a suspension condition is met, the terminal cancels the ESR message transmission, preventing the harmful repeated fallback to CS domain before it can occur
Solution Approach 2:
The patent converts the potential harm of ESR message retransmission into a benefit by using the suspension state information constructively. Instead of blindly retransmitting ESR messages which causes harmful repeated fallbacks, the system uses the suspension state detection to intelligently suppress retransmission, thereby protecting LTE service continuity while still allowing normal CSFB call establishment when appropriate
2Productivity
If the UE cancels ESR message retransmission when suspension conditions are met, then LTE service continuity is maintained, but the call establishment may be delayed
Solution Approach 1:
The patent applies dynamics by making the ESR message transmission behavior adaptive rather than static. The terminal dynamically adjusts its transmission behavior based on the real-time communication state of the CSFB call. When suspension conditions are detected, the terminal dynamically cancels retransmission to maintain LTE service continuity. When no suspension conditions exist, normal transmission proceeds, ensuring call establishment is not unnecessarily delayed
Data Source
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AI summary
A call processing method includes: determining (S11) that a circuit switched fallback (CSFB) call establishing process performed by the terminal is suspended, and a release message of radio resource control (RRC) connection redirected to a circuit domain is received, and determining a current communication state of the CSFB call; and cancelling (S12) transmitting an extended service request (ESR) message to be retransmitted currently, in response to determining that the current communication state of the CSFB call meets a condition for canceling a retransmission mechanism of the ESR message.