5G UE Reject Message Handling via Access Retry and Counter
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Solution Overview
Problem
The 5G wireless communication system lacks a protection mechanism against denial of service attacks, particularly for non-integrity protected reject messages, which can result in permanent rejection and denial of service to users, unlike previous systems like LTE and EPS.
Innovation Solution
The user equipment (UE) in the 5G system is designed to retry the 5G mobility management procedure over alternative access networks, including 3GPP and non-3GPP access, and employs a counter-based mechanism to determine when a rejection is genuine, allowing it to select a new access network based on priority rules and reset counters upon successful registration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the network sends non-integrity protected reject messages to protect against denial of service attacks, then network security is improved, but the UE cannot distinguish between genuine rejections and fraudulent attacks, leading to service denial
Solution Approach 1:
The patent segments the reject message handling by introducing a counter mechanism that tracks the number of non-integrity protected reject messages received. Instead of treating all rejections uniformly, the system divides the response into conditional paths: if the counter is below a threshold, the UE retries; if above, the UE treats it as genuine. This segmentation allows differentiation between fraudulent and genuine rejections.
Solution Approach 2:
The patent implements preliminary action by pre-configuring a counter and threshold value in the UE before encountering reject messages. This preliminary setup enables the UE to automatically respond to non-integrity protected reject messages without needing real-time authentication, allowing service continuity while maintaining security against coordinated attacks.
2Object-affected harmful factors
If the UE immediately treats reject messages as genuine to prevent fraud, then false connections are reduced, but legitimate service access is blocked due to potential fraudulent attacks
Solution Approach 1:
The patent applies dynamics by making the UE's response to reject messages adaptive rather than static. The counter mechanism dynamically adjusts the UE's behavior based on the frequency of received reject messages. For single or occasional rejections, the UE retries to maintain service access; for repeated rejections exceeding the threshold, the UE treats them as genuine to prevent fraud. This dynamic response resolves the contradiction between preventing fraud and maintaining legitimate access.
3Productivity
If the UE retries connections after receiving reject messages, then service continuity is improved, but network resources are consumed by potential attack traffic
Solution Approach 1:
The patent implements feedback through the counter mechanism that monitors and records the frequency of non-integrity protected reject messages. This feedback loop allows the UE to learn from past experiences and adjust its retry behavior accordingly. By comparing the current rejection count against the pre-configured threshold, the system provides feedback that determines whether to retry or stop, optimizing resource usage while maintaining service continuity when appropriate.
Data Source
AI summary
Methods and apparatus are provided for handling of non-integrity reject message in the 5G system. In one novel aspect, the UE upon receiving the reject message via one access without integrity protection, retries one or more other accesses for one or more times before treating the rejection genuine. In one embodiment, the UE attempts the same 5GMM procedure over another access in the same cell/tracking area (TA). The alternative access including other types of 3GPP access and non-3GPP access. Subsequently, the UE can search the service from another cell/TA or another PLMN. In one embodiment, if the UE receives reject cause invalidating the UE with one access without integrity protection, the UE tries the system a few times before treating the reject genuine by tracking an invalidating counter, which is increased by one each time the rejection is received with a cause value invalidating the UE.