PDCP Message Bypass for Low-Latency UE Data Delivery
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Solution Overview
Problem
Existing 5G NR systems face challenges in maintaining continuous user plane transmission when control plane connections fail due to unreliable cloud infrastructure, particularly for Ultra Reliable Low Latency Communication (URLLC) services, leading to service interruptions and failure to meet stringent latency and reliability requirements.
Innovation Solution
A mechanism is introduced to bypass the PDCP reordering process in the UE, allowing PDCP messages to be delivered directly to higher layers without waiting for sequence number verification, and a network mechanism to store and retrieve UE context at predefined intervals or upon specific events to ensure seamless resynchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PDCP reordering process is used to ensure reliable message delivery, then message delivery reliability is improved, but transmission latency increases
Solution Approach 1:
The patent dynamically adjusts the PDCP reordering process based on the reliability of the control plane connection. When the control plane connection is reliable, normal reordering is performed. When failure is detected, the reordering process is bypassed for user plane data, allowing dynamic adaptation to changing network conditions and resolving the contradiction between reliability and latency.
Solution Approach 2:
The patent changes the operational parameters of the PDCP layer by modifying the reordering behavior based on control plane connection status. The system transitions between different operational modes (normal reordering vs. bypass mode) by changing the parameter that controls whether reordering is applied, thus optimizing performance for different network conditions.
2Reliability
If dual radio capability is implemented to support independent control plane connections, then connection reliability is improved, but device cost increases
Solution Approach 1:
The patent makes the single control plane connection serve multiple functions: it not only controls the UE but also provides reliability information to the user plane PDCP layer. By making the control plane connection's status information multi-functional (used for both control and reliability assessment), the system achieves improved reliability without requiring additional radio hardware.
Solution Approach 2:
The patent introduces an intermediary mechanism where the control plane connection status acts as a mediator between the control plane and user plane. The status information from the control plane connection mediates the behavior of the user plane PDCP reordering process, allowing indirect reliability improvement without direct hardware duplication.
3Speed
If PDCP reordering is bypassed to reduce latency, then transmission speed is improved, but message delivery reliability deteriorates
Solution Approach 1:
The patent dynamically switches between reordering and bypass modes based on real-time control plane connection status. This dynamic adjustment allows the system to optimize for speed when the control plane is unreliable, while maintaining reliability when the control plane is functional, thus resolving the contradiction between speed and reliability.
Solution Approach 2:
The patent uses feedback from the control plane connection status to control the user plane PDCP reordering process. The control plane connection reliability information provides feedback that determines whether reordering should be applied or bypassed, creating a closed-loop system that adapts to maintain appropriate reliability levels while optimizing speed.
Data Source
AI summary
Methods and apparatus are provided. In an example aspect, a method in a User Equipment (UE) of providing data in a PDCP message to a layer above a PDCP layer is provided. The method includes receiving an indication that a PDCP message received at the UE should bypass a PDCP reordering process, and providing data in the PDCP message to a layer above a PDCP layer without using the PDCP reordering process.