UE AMBR Segmentation for Flexible Bitrate Management
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Solution Overview
Problem
The existing 5G NG-RAN architecture lacks a flexible method to manage user equipment (UE) aggregate maximum bit rate (AMBR) for dedicated radio bearers (DRBs), particularly in scenarios with split DRBs, which can lead to network performance impairment due to inflexible bit rate distribution across distributed units (DUs).
Innovation Solution
The proposed solution involves dividing the UE AMBR into shares and signaling these shares between the control unit's user plane (CU-UP) and control plane (CU-CP), allowing for dynamic distribution of bit rates across DRBs associated with different DUs, enabling flexible bit rate management and enforcement of maximum bit rates on DRBs and sets of DRBs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If maximum aggregate bitrate per DU is enforced, then network performance is protected from overload, but flexibility to shift traffic between DUs is lost when a DU is in outage
Solution Approach 1:
The UE AMBR is segmented into multiple bearer AMBRs, each associated with specific DRBs. This segmentation allows the gNB-CU-UP to enforce bit rate limits at the bearer level rather than at the DU level, enabling flexible traffic redistribution across DUs while maintaining overall rate control. When one DU is in outage, traffic can be shifted to other DUs within the constraints of the segmented bearer AMBRs.
2Ease of operation
If UE AMBR is divided into shares per DU, then bit rate distribution is controlled, but gNB-CU-UP flexibility to shift data traffic between DUs is constrained
Solution Approach 1:
The gNB-CU-UP acts as an intermediary between the gNB-CU-CP and the DUs, managing bearer AMBR enforcement centrally. This intermediary role allows the system to maintain bit rate distribution control through configured bearer AMBRs while enabling flexible traffic shifting decisions at the gNB-CU-UP, which can dynamically adjust traffic distribution across DUs without being constrained by DU-specific AMBR shares.
3Device complexity
If DU-specific AMBR shares are assigned, then maximum bit rate enforcement is simplified, but network performance degrades when a DU is in outage
Solution Approach 1:
The system transitions from static DU-specific AMBR shares to dynamic bearer AMBR enforcement managed by the gNB-CU-UP. This dynamic approach allows the system to maintain simple enforcement mechanisms while adapting traffic distribution in real-time based on DU availability. When a DU is in outage, the gNB-CU-UP can dynamically shift traffic to other DUs while continuing to enforce the configured bearer AMBRs, thus maintaining network performance without increasing enforcement complexity.
Data Source
AI summary
In one aspect, one or more network nodes configured to manage bitrates for dedicated radio bearers (DRBs) allocate (502) respective shares of a pre-determined aggregated maximum bit rate (AMBR) to a plurality of DRBs or to a plurality of sets of DRBs or to a combination of DRBs and sets of DRBs. The one or more network nodes also enforce (504) maximum bit rates on the DRBs and/or sets of DRBs, according to the allocated shares.