ACM Link Adaptation When Receiver Feedback Fails
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Solution Overview
Problem
Existing communication systems face challenges in managing variable-rate wireless communication links, particularly when feedback information from receivers is unusable due to channel conditions or equipment failures, leading to inefficiencies and potential data loss.
Innovation Solution
The implementation of Adaptive Coding and Modulation (ACM) systems that select Forward Error Correction (FEC) codes and modulation schemes based on feedback information, with the ability to switch to alternative ACM profiles independently or jointly across communication links to maintain link quality and meet Quality-of-Service (QoS) constraints, and temporarily disabling subsets of ACM profiles to ensure reliable data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If Adaptive Coding and Modulation (ACM) is used to transmit data at variable data rates, then the efficiency and adaptability of the communication link is improved, but the system becomes vulnerable to feedback information being unusable due to channel conditions or equipment failures
Solution Approach 1:
The system performs preliminary actions by pre-configuring multiple ACM profiles with different FEC codes and modulation schemes before channel conditions change. When feedback becomes unusable, the transmitter can immediately switch to alternative pre-defined profiles without waiting for feedback, thus maintaining continuous adaptive operation.
Solution Approach 2:
The system uses feedback information from the receiver to select appropriate ACM profiles for optimal data transmission. The feedback loop monitors channel conditions and adjusts the data rate accordingly, enabling the system to adapt to changing conditions while maintaining high efficiency.
2Reliability
If the transmitter continuously monitors and adjusts data rate based on feedback, then the quality of service is improved, but the system complexity increases due to the need for multiple ACM profiles and feedback processing
Solution Approach 1:
The system segments the ACM configuration into multiple discrete profiles, each containing specific FEC codes and modulation schemes. This segmentation allows the transmitter to manage different operational modes as separate, pre-defined units, simplifying the decision-making process when selecting appropriate profiles based on feedback information.
Solution Approach 2:
The system dynamically switches between different ACM profiles based on real-time feedback about channel conditions. This dynamic adaptation allows the system to optimize performance for current conditions while maintaining a manageable structure through predefined profile options.
3Productivity
If feedback information is used to determine data rate, then the communication efficiency is improved, but data loss may occur when feedback is unavailable or unusable
Solution Approach 1:
The system prepares multiple backup ACM profiles in advance that can be activated if feedback becomes unusable. This cushioning ensures that when feedback fails, the system can switch to alternative profiles without interrupting data transmission, preventing data loss due to inability to adapt to changing conditions.
Solution Approach 2:
The transmitter independently monitors feedback availability and autonomously decides when to switch from feedback-based rate adaptation to alternative ACM profiles. This self-service capability ensures continuous operation without relying on external feedback when it becomes unavailable.
Data Source
AI summary
A method for communication includes transmitting data from a transmitter to a receiver using Adaptive Coding and Modulation (ACM). The data rate is set by selecting, based on feedback, an ACM profile defining a Forward Error Correction code and a modulation scheme. Upon detecting that the feedback is unusable, an operation of the transmitter is changed independently of the feedback.In another method, data is exchanged over two opposite directions of a bidirectional link that uses ACM by communicating using two ACM profiles. A joint constraint is defined on the two directions. The two ACM profiles are set based on first and second measured reception quality metrics of the two link directions, to meet the joint constraint. In yet another method, a subset of the ACM profiles is temporarily disabled, and the data is transmitted using only the ACM profiles that are not disabled.