Fronthaul C-Plane ACK/NACK Extensions for Transmission Failure Detection
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Solution Overview
Problem
Current O-RAN fronthaul networks lack the ability for the sender to detect transmission failures or decoding failures of messages, leading to potential outages due to the lack of feedback on message reception and decoding status at the receiver.
Innovation Solution
A new section extension is introduced for acknowledgement/negative acknowledgement (ACK/NACK) requests, allowing the sender to request feedback on message reception and decoding status, with specific fields indicating the ACK/NACK request ID and size of the section extension, enabling robust message transmission and reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If no feedback mechanism is implemented in the fronthaul network, then the network structure remains simple and protocol overhead is minimized, but the sender cannot detect transmission failures or decoding failures leading to potential outages
Solution Approach 1:
The feedback mechanism is segmented into distinct components: an ACK/NACK request indicator field in the downlink C-plane message, and separate ACK/NACK response messages sent upstream. This segmentation allows the reliability feedback to be added without fundamentally restructuring the entire fronthaul protocol, thus improving reliability while controlling complexity growth.
Solution Approach 2:
A feedback mechanism is introduced where the receiver sends ACK/NACK responses to the sender based on successful reception and decoding of C-plane messages. The sender can set an ACK/NACK request indicator in the downlink message, and the receiver responds with appropriate acknowledgment or negative acknowledgment, enabling failure detection and retransmission without overwhelming protocol complexity.
2Reliability
If ACK/NACK feedback mechanism is added to detect transmission failures, then message transmission reliability is improved, but protocol overhead and message structure complexity increase
Solution Approach 1:
The ACK/NACK feedback is implemented as a partial action rather than requiring full protocol restructure. The ACK/NACK request indicator is only set when feedback is needed, and the full ACK/NACK response message is only transmitted when the indicator is present. This partial implementation reduces protocol overhead while maintaining the ability to detect transmission failures when necessary.
Solution Approach 2:
The ACK/NACK request indicator is nested within the existing C-plane message structure rather than requiring a separate message exchange. The indicator field is embedded in the downlink message, and the ACK/NACK response is nested within the uplink message structure, allowing feedback functionality to be integrated without adding significant external overhead to the protocol framework.
3Reliability
If no retransmission mechanism is implemented, then the system operates with simpler logic and faster processing, but lost or incorrectly decoded messages cause network outages
Solution Approach 1:
The system performs preliminary action by setting the ACK/NACK request indicator in the downlink C-plane message before transmission. This preliminary marking enables the receiver to prepare appropriate ACK or NACK responses, and allows the sender to anticipate the need for potential retransmission. The preliminary setup of the feedback request simplifies the overall error handling logic compared to implementing complex error detection and correction codes.
Data Source
AI summary
Methods and apparatuses for handling an acknowledgement of C-plane message in a wireless communication system. A method of a transmitter device comprises: generating a section extension for an ACK/NACK request including an ackNackReqId field and an extLen field, wherein the ackNackReqId field indicates the ACK/NACK request ID of a section description and the extLen field indicates a size of the section extension; transmitting, to a receiver device, the C-plane message including the section extension for the ACK/NACK request; and receiving, from the receiver device, an ACK message corresponding to the C-plane message.