gNB CU-UP Data Forwarding for NR Handover
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Solution Overview
Problem
Handover processes in cellular networks, particularly in disaggregated base stations, often result in undesirable effects such as lost packets and congestion due to challenges in communication between mobile devices and base stations.
Innovation Solution
The implementation of a method that involves a Next Generation Node-B (gNB) with a central unit (gNB-CU) and a distributed unit (gNB-DU), which facilitates efficient handover by encoding XnAP handover requests and initiating data forwarding between gNBs, using XnAP and E1AP messages to manage user equipment context and bearer operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If handover is performed in disaggregated base station, then mobility management is enabled, but packet loss and interface congestion occur
Solution Approach 1:
The base station is divided into separate control plane (gNB-CU) and user plane (gNB-DU) functions. The control plane handles mobility management and signaling, while the user plane handles data forwarding. This segmentation allows independent optimization of control and data paths, preventing congestion propagation and reducing packet loss during handover.
Solution Approach 2:
The F1 interface acts as an intermediary between the gNB-CU and gNB-DU, enabling coordinated control of handover procedures. The E1 interface serves as intermediary for communication between CU-CP and CU-UP entities, facilitating synchronized user plane context setup during handover to minimize data loss.
2Adaptability or versatility
If handover is performed in disaggregated base station, then mobility management is enabled, but interface congestion occurs
Solution Approach 1:
By segmenting the base station into separate control and user plane functions connected via F1 interface, the patent creates independent processing paths. This segmentation distributes the handling of control messages and user data, preventing interface congestion and enabling parallel processing of handover procedures.
Solution Approach 2:
The target gNB-DU performs preliminary actions by receiving and processing the handover request before actual data forwarding begins. The user plane context is established in advance, and data forwarding is pre-configured, so that when handover executes, the path is already ready, reducing processing delays and interface congestion.
3Productivity
If control plane and user plane are separated, then signaling efficiency is improved, but coordination complexity increases
Solution Approach 1:
The separation of control plane (gNB-CU) and user plane (gNB-DU) into independent functional entities with standardized F1 interface enables parallel processing of control signaling and user data. This segmentation improves signaling efficiency by allowing simultaneous execution of handover procedures without blocking data forwarding operations.
Solution Approach 2:
The F1 interface implements feedback mechanisms where the gNB-CU receives status information from the gNB-DU about user plane context setup and data forwarding completion. This feedback enables the control plane to coordinate handover procedures effectively while maintaining independence, reducing coordination complexity through automated status monitoring and adjustment.
Data Source
AI summary
Embodiments of a Next Generation Node-B (gNB) and methods of communication are disclosed herein. The gNB may be configurable to operate as a source gNB (S-gNB). The S-gNB may transfer, from a control plane (CU-CP) of the S-gNB to a CU-CP of a target gNB (T-gNB), an XnAP handover request message that indicates an Xn handover of a User Equipment (UE) from the S-gNB to the T-gNB. The S-gNB may initiate data forwarding, from a user plane (CU-UP) of the S-gNB to a CU-UP of the T-gNB, of downlink data packets. The data forwarding may be terminated based on reception of end marker packets from a user plane function (UPF) entity. The CU-UP of the S-gNB may transfer end marker packets to the CU-UP of the S-gNB to indicate termination of the data forwarding.