Explicit NACK Frame for Wireless Link Adaptation
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Solution Overview
Problem
Current wireless communication systems face challenges in providing efficient feedback for failed radio transmissions without adversely affecting legacy devices, as they often rely on implicit NACK mechanisms that may not provide sufficient information for link adaptation and retransmissions.
Innovation Solution
The method involves generating a second radio transmission that includes an explicit failure indication, decodable by both new generation and legacy devices, using techniques such as overlaying additional information onto legacy messages, like ACK frames, to convey NACK messages without disrupting legacy device operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If explicit NACK messages are introduced to provide feedback for failed transmissions, then link adaptation and retransmission efficiency are improved, but legacy devices are adversely affected and blocked from radio channel access
Solution Approach 1:
The patent uses an intermediary approach by introducing a new message type (NACK frame) that coexists with legacy ACK frames. The NACK frame serves as a mediator that carries explicit negative acknowledgment information without disrupting the existing ACK frame structure that legacy devices rely upon. This allows new devices to utilize explicit NACK feedback while legacy devices continue to operate with implicit NACK based on absent ACK frames.
Solution Approach 2:
The feedback mechanism is segmented into separate message types: ACK frames for successful reception and NACK frames for failed reception. This segmentation allows the system to provide explicit feedback for failed transmissions through NACK frames while maintaining the traditional ACK frame behavior for successful transmissions, thereby preserving legacy device compatibility.
2Device complexity
If implicit NACK mechanism is used to minimize protocol overhead, then device complexity is reduced, but sufficient information for link adaptation and retransmissions is not provided
Solution Approach 1:
The system dynamically selects between implicit and explicit NACK mechanisms based on device capability. New devices that support the NACK frame utilize explicit feedback for comprehensive information, while legacy devices continue with the simpler implicit mechanism. This dynamic adaptation allows the system to optimize feedback information completeness without universally increasing protocol overhead.
3Productivity
If additional information is included in ACK frames to provide feedback for failed transmissions, then link adaptation is improved, but legacy devices cannot distinguish between successful and failed reception indications
Solution Approach 1:
Instead of modifying ACK frames to carry NACK information (which would confuse legacy devices), the patent inverts the approach by creating a dedicated NACK frame structure. This NACK frame explicitly indicates failed reception, while the traditional ACK frame structure remains unchanged for successful receptions. This inversion resolves the ambiguity issue while providing comprehensive feedback information.
Data Source
AI summary
A first radio device receives a first radio transmission from a second radio device. In response to reception of the first radio transmission by the first radio device being unsuccessful, the first radio device sends a second radio transmission to the second radio device. The second radio transmission comprises an indication to the second radio device that reception of the first radio transmission by the first radio device was unsuccessful. The first radio device generates the second radio transmission to be decodable by one or more other radio devices than the second radio device as comprising a positive acknowledgement message, indicating to the second radio device that reception of the first radio transmission by the first radio device was successful, as comprising a clear-to-send message to the second radio device, or as some other legacy message supported by the other radio device(s).