MCS Selection Using ACK/NACK Feedback for Dynamic Link Adaptation
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently adapting modulation and coding schemes to dynamic channel conditions, particularly in ultra-reliable and low-latency communications, leading to resource wastage or failure to meet reliability and data rate requirements due to outdated feedback-based MCS selection.
Innovation Solution
A method using reinforcement learning to estimate channel state information through ACK/NACK feedback, calculating a posteriori probability distribution, and selecting an optimal modulation and coding scheme by sampling this distribution, considering historical data and location information to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If feedback-based MCS selection is used, then link adaptation is enabled, but accuracy of channel state estimation deteriorates leading to resource wastage or failure to meet requirements
Solution Approach 1:
The system performs preliminary actions by calculating a posteriori probability distributions and computing expected values before actual transmission occurs. Historical channel quality information and location data are processed in advance to predict optimal MCS, enabling accurate channel state estimation before the transmission takes place.
Solution Approach 2:
The system utilizes feedback mechanisms by incorporating ACK/NACK feedback and CQI feedback into the MCS selection process. The access node continuously monitors transmission outcomes and channel conditions, using this feedback to refine and update the probability distributions for future MCS selection, thereby improving estimation accuracy over time.
2Reliability
If conservative MCS selection is used to meet reliability requirements, then error probability is reduced, but data rate and resource efficiency deteriorate
Solution Approach 1:
The system dynamically changes the MCS parameters by selecting from multiple possible modulation and coding schemes based on calculated probability distributions. Instead of using a fixed conservative approach, the system adjusts MCS parameters adaptively, choosing higher order modulation when channel conditions indicate low error probability, and falling back to more robust schemes when reliability is compromised, thus optimizing the trade-off between reliability and data rate.
3Adaptability or versatility
If frequent MCS reselection is performed to adapt to changing channels, then channel condition utilization is improved, but processing complexity and latency increase
Solution Approach 1:
The system performs preliminary calculations of a posteriori probability distributions and expected values before MCS selection is needed. By pre-processing historical channel quality information and location data, the system reduces the computational burden during actual transmission decisions, enabling frequent adaptations without proportionally increasing processing complexity.
Solution Approach 2:
The system employs self-service mechanisms where the access node automatically updates probability distributions and selects MCS without requiring complex external intervention. The algorithm self-adjusts based on incoming feedback and channel conditions, simplifying the control logic and reducing processing overhead while maintaining effective channel adaptation.
Data Source
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AI summary
A modulation and coding scheme for a transmission to an apparatus may be selected by at least sampling a posteriori probability distribution that has been calculated using a first probability distribution and a second probability distribution. The first probability distribution is calculated using at least a newest first feedback and a plurality of older first feedbacks, a first feedback indicating channel quality. The second probability distribution is calculated using at least a newest second feedback and a plurality of older second feedbacks, a second feedback indicating a success or failure of an earlier transmission transmitted from the apparatus.