Wireless Backhaul F1AP Message Transmission via LTE Uu Interface
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Solution Overview
Problem
Current signaling transmission solutions in the NSA mode for IAB networks do not specifically address how to transmit F1AP messages between the IAB node DU and the IAB donor CU, posing a technical challenge.
Innovation Solution
A wireless backhaul system and communication method that involves generating F1AP messages on the DU, mapping them to a signaling-plane bearer of the LTE Uu interface, and sending them to the MT function unit, which then encapsulates these messages into X2AP messages for transmission to the secondary base station CU, ensuring reliable F1AP message transmission between the IAB node DU and the IAB donor CU.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If F1AP messages are transmitted between IAB node DU and IAB donor CU in NSA mode using existing signaling solutions, then communication can be established, but the transmission path and protocol mapping are not specifically defined, leading to implementation ambiguity
Solution Approach 1:
The patent introduces an intermediary mechanism where the F1AP message is first encapsulated into an X2AP message at the DU side, then mapped to an NR RRC message container, and finally transmitted through the LTE Uu interface. This multi-layer encapsulation acts as an intermediary that bridges the F1 interface (between DU and CU) and the Uu interface (between MT and primary base station), resolving the ambiguity in transmission path definition.
Solution Approach 2:
The patent implements a nested message structure where the F1AP message is nested within an X2AP message, which is in turn nested within an NR RRC message container. This nested doll approach allows the F1AP message to be transported through the LTE interface by embedding it within protocol layers that are natively supported by the interface, thereby defining a clear transmission path without adding external complexity.
2Adaptability or versatility
If existing signaling transmission solutions are used without specific F1AP message transmission definitions, then general communication functionality is maintained, but specific F1AP message routing and protocol adaptation are ambiguous
Solution Approach 1:
The patent segments the F1AP message transmission process into distinct stages: (1) F1AP message generation at DU, (2) encapsulation into X2AP message, (3) mapping to NR RRC message container, (4) transmission through LTE Uu interface, and (5) extraction and delivery at CU. This segmentation provides clear routing instructions at each stage, making the overall process easier to implement and operate while maintaining adaptability through the standardized encapsulation formats.
3Adaptability or versatility
If F1AP messages are transmitted through LTE eNB as primary base station, then NSA mode operation is enabled, but the message format adaptation between NR and LTE protocols is not specifically addressed
Solution Approach 1:
The patent applies parameter changes by transforming the F1AP message format through multiple protocol layers. The message format is changed from native F1 interface format to X2AP format, then to NR RRC container format, and finally to LTE Uu interface format. Each transformation step modifies specific parameters (message structure, encoding, header fields) to match the target interface requirements, ensuring protocol format accuracy while maintaining NSA mode compatibility.
Data Source
AI summary
A wireless backhaul method, including: a wireless backhaul device generates a first F1AP message, maps the first F1AP message to a signaling-plane bearer of an LTE Uu interface, and sends the first F1AP message to a primary base station of the wireless backhaul device via the signaling-plane bearer of the LTE Uu interface. The primary base station obtains the first F1AP message via the signaling-plane bearer of the LTE Uu interface, encapsulates the first F1AP message into a first X2AP message, and sends the first X2AP message to a secondary base station of the wireless backhaul device. The secondary base station receives the first X2AP message and obtains the first F1AP message based on the first X2AP message.