CU-DU Handover Control for 5G IoT Wireless Systems
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Solution Overview
Problem
In 5G communication systems, existing handover methods between distributed units (DUs) in an evolved node B (eNB) architecture face challenges in efficiently managing data transmission during inter-DU handovers, leading to delays and redundancy due to the separation of central units (CUs) and DUs, which complicates the signaling process and affects user equipment mobility.
Innovation Solution
A method and apparatus for controlling handover between DUs by signaling with a central unit (CU) that involves transmitting specific messages for handover initiation, downlink data delivery, and radio resource control reconfiguration, allowing for early forwarding of data to a target DU before complete reconfiguration, thereby reducing transmission delays and redundancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If existing handover methods are used between DUs in eNB architecture, then handover control can be maintained, but transmission delays and redundancy occur due to CU-DU separation
Solution Approach 1:
The patent applies preliminary action by enabling the target DU to receive and prepare downlink data before the handover is complete. The CU forwards downlink data to the target DU in advance based on handover indication, allowing the target DU to have data ready when the UE actually switches, thereby reducing transmission delays during handover.
Solution Approach 2:
The CU acts as an intermediary between the source DU and target DU during handover. It receives handover indication from the source DU, determines downlink data to forward, and sends this data to the target DU. This intermediary role streamlines the handover process by centralizing control and reducing direct signaling complexity between DUs.
2Loss of time
If downlink data is forwarded early to target DU before complete reconfiguration, then transmission delays are reduced, but data transmission accuracy may be affected
Solution Approach 1:
The patent implements feedback mechanisms where the source DU sends handover indication messages to the CU, and the CU forwards data to the target DU based on this feedback. The target DU also provides feedback through random access procedures and RRC reconfiguration complete messages, ensuring that early data forwarding is coordinated with actual handover completion status.
Solution Approach 2:
The CU performs preliminary action by determining and forwarding downlink data to the target DU before the handover is fully complete. This preliminary data preparation reduces the time needed for actual data transmission after handover, while the feedback mechanism ensures accuracy.
3Reliability
If handover signaling is coordinated between CU and DUs, then service continuity is improved, but signaling overhead increases
Solution Approach 1:
The patent extracts the handover control function from the individual DUs and centralizes it in the CU. The CU handles the complex signaling of determining downlink data and coordinating with both source and target DUs, while the DUs themselves have simplified roles. This extraction improves service continuity through centralized control while managing signaling overhead by reducing redundant messages between DUs.
Data Source
AI summary
A method and apparatus are provided that controls the handover between DUs in an eNB including a CU and a DU. The method and system fuses 5G communication systems with IoT technology to transmission data at a high rate after 4G systems. The communication method and system is applied to intelligent services, based on 5G communication technology and IoT related technology. The method includes transmitting, to a source DU of the base station, a first message related to a handover; receiving, from the source DU, a second message for downlink data delivery information related to a PDU transmitted from the source DU to a terminal; receiving, from a target DU of the base station, a third message based on a random access procedure of the terminal toward the target DU; and transmitting, to the target DU, downlink data based on the downlink data delivery information after receiving the third message.