Link Adaptation via Interference Probability Distribution
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Solution Overview
Problem
In wireless communication systems, channel quality feedback information used for scheduling and link adaptation becomes unreliable due to discontinuous interference in packet-switched systems, leading to errors in downlink transmissions as interference conditions change rapidly.
Innovation Solution
Mobile terminals derive channel quality feedback information based on the probability of interference present, using statistical distributions of interference measurements to provide more reliable feedback to the base station, which then adjusts transmission parameters accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If channel quality feedback information is derived from a single interference measurement, then the feedback is quickly obtained, but the feedback becomes unreliable due to discontinuous interference changes
Solution Approach 1:
The mobile terminal performs preliminary actions by measuring interference multiple times before deriving channel quality feedback information. Instead of using a single instantaneous measurement, the terminal accumulates multiple interference measurements and derives feedback based on this accumulated data, ensuring the feedback reflects the statistical characteristics of interference rather than transient fluctuations.
Solution Approach 2:
The system implements a feedback mechanism where the mobile terminal continuously monitors interference and updates channel quality feedback information based on changing interference conditions. The base station uses this feedback to adapt transmission parameters, creating a closed-loop system that responds to interference variations while maintaining reliable communication.
2Measurement precision
If interference measurements are averaged over a longer period, then random noise errors are reduced, but the measurements become outdated due to discontinuous interference
Solution Approach 1:
The mobile terminal performs a limited number of interference measurements - not a single measurement and not an excessive long-term average, but an optimal number of measurements that balances precision and timeliness. This partial action approach derives channel quality feedback from a sufficient sample of interference measurements to reduce random noise errors while ensuring the feedback remains current and reliable for discontinuous interference conditions.
3Productivity
If channel quality feedback indicates less interference than actually present, then data rate is increased, but transmission errors occur
Solution Approach 1:
The system uses feedback from multiple interference measurements to derive accurate channel quality information, which the base station uses to select appropriate transmission parameters. This feedback mechanism ensures that data rates are optimized based on actual interference conditions rather than transient measurements, maintaining both high productivity and transmission reliability.
Solution Approach 2:
The base station dynamically changes transmission parameters including data rate, modulation scheme, and coding rate based on derived channel quality feedback. When interference is high, the system transitions to more robust but lower-rate parameters; when interference is low, it uses higher-rate parameters, thereby optimizing the trade-off between productivity and reliability according to actual channel conditions.
4Reliability
If channel quality feedback indicates more interference than actually present, then transmission reliability is maintained, but data rate is reduced below optimal
Solution Approach 1:
The system performs a sufficient but not excessive number of interference measurements to derive channel quality feedback. This partial action approach ensures that random noise does not cause overestimation of interference, which would unnecessarily reduce data rates. The optimal number of measurements maintains transmission reliability while avoiding excessive conservatism that would limit productivity.
Data Source
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AI summary
A mobile terminal measures interference over multiple measurement periods and generates interference probability data based on the statistical distribution of the interference measured. The interference probability data may describe, for example, the probability of each possible level of interference expected at the mobile terminal. The mobile terminal derives channel quality information as feedback to a base station based on this interference probability data (e g., when noise at the mobile terminal falls below a threshold) Ln one embodiment the mobile terminal does so by estimating from the interference probability data the probability of success folly receiving a transmission if certain feedback information is reported. Derived in this way, the feedback information more reliably indicates interference likely present at the mobile terminal when the base station sends the transmission. Accordingly, the base station controls the transmission based on the feedback information, and in some embodiments, also based on the interference probability data.