HFN Synchronization for Packet Loss Handling in LTE Voice Calls
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Solution Overview
Problem
In LTE networks, bulk packet loss during voice calls can cause deciphering failures due to de-synchronization of hyper frame numbers (HFN) between user equipment (UE) and evolved Node B (eNB), leading to call disconnections.
Innovation Solution
A method and apparatus that receive uplink packets, decipher them based on a first HFN, and change the HFN value to a second HFN in case of deciphering failure, allowing further deciphering to maintain call continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If packet loss occurs during voice call in LTE network, then call disconnection happens due to HFN de-synchronization, but maintaining continuous connection requires preventing deciphering failure
Solution Approach 1:
The system detects packet loss before it causes complete HFN de-synchronization and call disconnection. By monitoring for deciphering failures and proactively adjusting the HFN counter at the eNB side to match the UE side, the system cushions against the harmful effects of packet loss and maintains call continuity.
Solution Approach 2:
The system implements a feedback mechanism where the eNB monitors deciphering results of received packets. When deciphering failure occurs, the system detects HFN de-synchronization and adjusts the HFN counter accordingly, creating a closed-loop control that maintains synchronization between UE and eNB despite packet loss conditions.
2Reliability
If HFN value is changed to recover from deciphering failure, then call continuity is maintained, but system complexity increases due to additional HFN management
Solution Approach 1:
The system performs self-diagnosis and self-correction by monitoring its own deciphering operations. When the eNB detects deciphering failure, it automatically identifies the HFN de-synchronization issue and adjusts its own HFN counter without external intervention, maintaining call continuity through autonomous error correction.
Solution Approach 2:
The system dynamically changes the HFN parameter value at the eNB side to restore synchronization with the UE. By adjusting this critical parameter in response to detected deciphering failures, the system maintains call continuity while managing the complexity through conditional parameter modification rather than constant monitoring.
Data Source
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AI summary
A method and an apparatus for handling packet loss in a mobile communication network are provided. In the method for handling a call when packet loss occurs, the apparatus receives an uplink packet from a user equipment (UE) and deciphers the packet based on a first hyper frame number (HFN). When the deciphering based on the first HFN fails, the apparatus changes an HFN value from the first HFN to a second HFN and then further deciphers the packet based on the second HFN.