Event-Driven Link Adaptation Algorithm for Wireless Stations
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Solution Overview
Problem
Existing link adaptation methods for wireless transmissions, particularly in VoIP applications, face challenges in measuring link quality due to the infrequent nature of voice packets and limited power resources in battery-powered devices, leading to inefficiencies in energy consumption and throughput.
Innovation Solution
An event-driven, power-optimized link adaptation algorithm that uses retransmissions per time unit (ReTXrate) and acknowledgement absence as metrics to dynamically adjust PHY parameters such as TX power and rate, minimizing energy consumption by selecting the most energy-efficient settings for frame exchanges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PER (Packet Error Rate) is used as a link quality metric, then link quality can be measured, but power consumption increases and throughput is reduced due to the need for multiple packet transmissions to obtain statistically valid PER
Solution Approach 1:
The patent extracts the essential link quality measurement function from the PER calculation process. Instead of using PER which requires multiple packets, the invention uses immediate feedback from single packet transmissions (ACK/NACK) combined with retransmission count tracking to obtain link quality metrics, thereby eliminating the need for statistical accumulation and reducing power consumption.
Solution Approach 2:
The patent replaces the expensive and time-consuming PER measurement approach with a cheaper, more efficient metric based on immediate transmission feedback. By using disposable-like single-packet ACK/NACK responses and retransmission counters, the system obtains sufficient link quality information without the overhead of prolonged measurement periods required for statistically valid PER.
2Measurement precision
If PER is used as a link quality metric, then link quality can be measured, but throughput is reduced because VoIP packets are infrequent and require multiple transmissions to generate valid PER statistics
Solution Approach 1:
The patent extracts link quality measurement capability from the PER statistical process. By using immediate ACK/NACK feedback and retransmission count tracking, the system obtains link quality metrics without requiring multiple VoIP packets, thereby maintaining throughput while enabling accurate measurement.
Solution Approach 2:
The patent implements a feedback mechanism that uses immediate ACK/NACK responses and retransmission counts to continuously update link quality metrics. This feedback approach allows the system to adapt to channel conditions in real-time without waiting for statistical convergence, thereby maintaining high throughput while measuring link quality accurately.
3Use of energy by moving object
If PHY rate adaptation is implemented without TPC, then energy consumption is reduced, but link quality deteriorates due to inability to optimize transmission power
Solution Approach 1:
The patent implements dynamic adjustment of both PHY rate and TX power based on real-time link quality feedback. The system dynamically selects optimal combinations of rate and power levels by monitoring ACK/NACK patterns and retransmission counts, thereby achieving both energy efficiency and reliable link quality through adaptive coordination of multiple parameters.
Solution Approach 2:
The patent changes multiple PHY parameters simultaneously (rate and TX power) based on link quality conditions. By adjusting both parameters together rather than fixing one, the system optimizes the trade-off between energy consumption and link quality, selecting parameter combinations that maximize performance for current channel conditions.
4Object-generated harmful factors
If TPC is implemented with structured power control, then interference is reduced, but device complexity increases due to additional control mechanisms
Solution Approach 1:
The patent implements self-service power control where the system automatically adjusts TX power based on observed transmission success/failure patterns and retransmission counts. The algorithm self-tunes power levels without external intervention, using the inherent feedback from ACK/NACK and retransmission behavior to optimize power consumption and interference reduction.
Solution Approach 2:
The patent uses feedback from transmission outcomes (ACK/NACK, retransmission counts) to automatically adjust TX power. This feedback-driven approach enables the system to learn optimal power levels from actual transmission behavior, reducing interference and improving energy efficiency without requiring complex external control mechanisms.
Data Source
AI summary
An event-driven, power-saving method of controlling link adaptation for wireless transmission in battery powered stations through selectively controlled PHY parameters uses a PHY parameter controller for selectively changing the PHY parameters. The number of retransmissions required per time unit (herein ReTXrate), and missing ACK numbers (e.g., more than two) are used as first and second link quality metrics in the method, instead of the PER as in prior art. Also, the measured ReTXrate after each packet transmission is used for establishing lower and higher thresholds for the ReTXrate. Based on the lower and higher ReTXrate thresholds and based on said missing ACKs, link adaptation by way of changing the PHY parameters through the PHY parameter controller is triggered. The link adaptation method is especially suitable for VoIP traffic but applies to non VoIP traffic too (e.g., data,) including FTP and web browsing situations, and conserves battery power in mobile stations.