5G User-Plane Mode Selection for Flexible CU/DU Traffic Handling

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

The existing radio access network architectures, such as those in 3G and 4G, lack flexibility in user-plane protocol layer distribution, which is inadequate for the diverse and complex traffic requirements of 5G networks, including high bandwidth, low latency, and reliable services.

Innovation Solution

A method and apparatus for dynamically selecting and adjusting user-plane protocol-layer modes between centralized and distributed units in a 5G RAN architecture, allowing flexible distribution of protocol layers based on traffic type and requirements, using a CU/DU architecture to optimize latency, bandwidth, and QoS.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a fixed user-plane protocol layer distribution is used in traditional RAN architecture, then the system structure is simple, but the system cannot adapt to diverse 5G traffic requirements including high bandwidth and low latency services

Engineering Contradiction:
Improveadaptability to diverse traffic requirementsVSAvoidsystem structure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The user-plane protocol stack is segmented into multiple configurable parts that can be distributed between CU and DU. The PDCP layer can be placed in CU while RLC/MAC layers can be in DU, or vice versa depending on traffic requirements. This segmentation allows flexible adaptation to different service types without requiring complete architectural redesign.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic user-plane mode selection where the network can switch between different protocol layer distribution modes (e.g., option 1-8) based on real-time traffic characteristics. This dynamic adjustment enables the system to adapt to varying service demands while maintaining a manageable system structure through standardized switching mechanisms.

Inventive Principle:
Principle #15Dynamics

2Quantity of substance

If protocol layers are distributed closer to the network core, then bandwidth utilization is improved, but transmission latency increases for edge services

Engineering Contradiction:
Improvebandwidth utilizationVSAvoidtransmission latency
Core Design Contradiction:
Quantity of substanceVSLoss of time

Solution Approach 1:

Different protocol layers are assigned to different network nodes based on local service requirements. For example, PDCP layer processing can be localized at CU for bandwidth-intensive services, while RLC/MAC layers are kept at DU for low-latency edge services. This local quality differentiation allows simultaneous optimization of bandwidth utilization and transmission latency for different service types.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent introduces an additional dimension of flexibility by allowing multiple user-plane mode options (option 1-8) that represent different protocol layer distribution configurations. This dimensional expansion enables the system to select optimal bandwidth-latency tradeoffs for various services without being constrained to a single fixed architecture.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Loss of time

If more protocol layers are deployed in distributed units, then service latency is reduced, but system complexity and deployment difficulty increase

Engineering Contradiction:
Improveservice latencyVSAvoiddeployment ease
Core Design Contradiction:
Loss of timeVSEase of manufacture

Solution Approach 1:

The patent establishes a standardized set of user-plane mode options (option 1-8) that predefine protocol layer distribution configurations. These pre-configured modes simplify deployment by providing ready-made solutions for different service scenarios, reducing the complexity of custom configuration while still enabling low-latency performance when needed.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system manages deployment complexity by parameterizing the protocol layer distribution through selectable modes rather than requiring custom configuration. By changing the user-plane mode parameter, the system can achieve different latency performances without increasing deployment difficulty, as all modes follow the same standardized configuration process.

Inventive Principle:
Principle #35Parameter changes

4Productivity

If user-plane protocol layers are flexibly distributed between CU and DU, then traffic requirements are better met, but configuration and management complexity increases

Engineering Contradiction:
Improvetraffic requirement satisfactionVSAvoidconfiguration complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent creates a universal user-plane mode selection mechanism that can handle diverse traffic requirements through a standardized set of options. The same mode selection framework serves multiple service types (eURLLC, eMBB, mMTC) and different protocol layer distributions, reducing configuration complexity through universality while maintaining high productivity in meeting traffic requirements.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP3675405B1User plane mode selection method, adjustment method, device, equipment and medium
Publication Date: 2025.11.05 ZTE CORP
  • EP3675405B1 patent drawingFigure 1~3
  • EP3675405B1 patent drawingFigure 4~5
  • EP3675405B1 patent drawingFigure 6~7

AI summary

Disclosed is a method for selecting a user-plane mode. The method includes that a centralized unit (CU) acquires a user-plane protocol-layer division mode supported by all cells in a service area of broadcast or multicast traffic, and determines a user-plane protocol-layer division mode of the broadcast or multicast traffic based on the centralized unit and a distributed unit according to the user-plane protocol-layer division mode supported by all cells. Further disclosed are a method and apparatus for selecting a user-plane mode, a method and apparatus for adjusting a user-plane mode, a centralized unit device, a core network element, and a storage medium.