UE Traffic Fallback During 5G Slice-Unaware RAN Handover
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Solution Overview
Problem
Existing wireless communication systems face challenges in mitigating Quality of Service (QoS) impact during unavailability of radio access network (RAN) support for network slicing, particularly in 5G NR systems, leading to degraded user experience and inefficient data transmission.
Innovation Solution
User Equipment (UE) devices implement strategies such as back-off periods, timer-based retries, and default radio bearer establishment to manage network slice PDU failures, monitor user experience metrics, and switch to default bearers when network slicing is unsupported, ensuring seamless data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE continuously retries network slice PDU establishment requests, then the network slice connectivity may be restored, but the user experience degrades due to repeated transmission failures and increased latency
Solution Approach 1:
The patent implements a back-off mechanism where the UE applies exponential back-off timing between retry attempts. Instead of continuous retry, the UE waits for progressively longer periods (e.g., 1 second, 2 seconds, 4 seconds) between each retry attempt. This periodic action with increasing intervals reduces the frequency of failed transmission attempts, thereby improving user experience while maintaining eventual connectivity restoration capability.
2Speed
If the UE immediately re-attempts network slice PDU establishment after failure, then connectivity restoration is faster, but QoS degradation occurs due to repeated failures affecting data transmission
Solution Approach 1:
The patent establishes a default data radio bearer (DRB) as a preliminary action before network slice PDU establishment fails. When the default DRB is already in place, the UE can route data through this reliable path during the back-off period, preventing QoS degradation. This preliminary preparation ensures that even if slice establishment fails, data transmission continuity is maintained, thus preserving QoS while allowing faster retry attempts.
3Reliability
If the UE implements exponential back-off with default bearer establishment, then QoS is maintained during retries, but the device complexity increases due to additional state management
Solution Approach 1:
The patent makes the back-off mechanism and default bearer establishment universal by implementing them as standardized procedures applicable to all network slice PDU establishment scenarios. The UE maintains a universal back-off counter and default DRB state that can be applied regardless of which specific network slice is being established. This multi-functional approach allows the same mechanism to handle various slice types (eMBB, URLLC, mMTC) and failure scenarios, reducing the need for separate complex state management for each case.
Data Source
AI summary
Apparatuses, systems, and methods for QoS impact mitigation during unavailability of RAN support of network slicing, e.g., in 5G NR systems and beyond. A UE may determine, while connected to a first cell of a network, whether handover instructions include DRB setup instructions on a second cell of the network for a PDU session established towards a first network slice on the first cell. The UE may, upon expiration of a timer initiated in response to the determination and/or confirmation that the second cell does not support network slicing, route, upon determining that there is not a neighboring cell that supports the first network slice and/or that there is not a routing rule for the first network slice that allows routing of traffic to another established DRB, user plane traffic to an eMBB DRB.