IAB Donor CU Uplink Data Lossless Transmission
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Solution Overview
Problem
In wireless communication systems, particularly in 5G NR, there is a challenge in ensuring lossless uplink data transmission during handovers between IAB-nodes, as part of the uplink data may not arrive at the IAB-donor CU due to multi-hop wireless backhaul, leading to potential data loss during handover procedures.
Innovation Solution
The method involves the IAB-donor CU receiving a delivery status of uplink data from the source IAB-node, transmitting a message to the control plane if data is incomplete, and only proceeding with handover once all data is received, ensuring that a SN Status Transfer message is sent only after complete data transfer, thereby preventing data loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If handover is performed quickly to improve mobility, then handover speed is improved, but uplink data may be lost during the handover process
Solution Approach 1:
The source IAB-donor CU receives and stores uplink data from the wireless device before the handover is executed. The delivery status is checked in advance, and data is buffered at the source CU until confirmation that it has been successfully received, ensuring no data is lost during the actual handover transition.
Solution Approach 2:
The source IAB-node provides feedback to the source IAB-donor CU about the delivery status of uplink data. This feedback mechanism allows the source CU to determine whether data has been successfully received before completing the handover, enabling data integrity verification without delaying the handover process.
2Reliability
If uplink data is buffered at source IAB-node to ensure complete data transfer, then data integrity is improved, but handover delay increases
Solution Approach 1:
The function of buffering and storing uplink data is extracted from the source IAB-node and relocated to the source IAB-donor CU. This allows the source IAB-node to quickly forward data without prolonged buffering, while the source CU maintains responsibility for data completeness, reducing handover delay while ensuring data integrity.
Solution Approach 2:
The data transfer process continues uninterrupted during handover preparation. The source CU receives data continuously from the wireless device via the source IAB-node and stores it in buffer memory, maintaining the data flow without interruption while preparing for handover, thus avoiding delays.
3Reliability
If delivery status is continuously monitored to prevent data loss, then data reliability is improved, but system complexity increases
Solution Approach 1:
A feedback mechanism is implemented where the source IAB-node reports the delivery status of uplink data to the source IAB-donor CU. This allows the source CU to determine whether data has been successfully received without complex continuous monitoring, simplifying the control process while ensuring data reliability.
Solution Approach 2:
The source IAB-node autonomously determines and reports the delivery status of data it has forwarded to the source CU. This self-service approach allows the node to independently assess whether data transmission was successful without requiring complex external verification mechanisms, reducing overall system complexity.
Data Source
AI summary
A method and apparatus for lossless uplink data transmission of IAB network in a wireless communication system will be provided. A user plane (UP) of an integrated access and backhaul (IAB)-donor central unit (CU) in a wireless communication system receives, from a wireless device, uplink data through a source IAB-node. A UP of an IAB-donor CU receives, from the source IAB-node, at least one of a delivery status of the uplink data on the source IAB-node, wherein the wireless device handovers from the source IAB-node to a target IAB-node. A UP of an IAB-donor CU transmits, to a unit-control plane (CP) of the IAB-donor CU, a first message based on the at least one of the delivery status of the uplink data.