Channel Quality Information Generation for Wireless Link Adaptation
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Solution Overview
Problem
Existing wireless communication systems face challenges in accurately determining output signal quality, especially in non-linear receivers and under rapidly changing channel conditions, leading to unreliable link adaptation and control errors.
Innovation Solution
The system employs two modes of operation to determine channel quality information based on the reliability of propagation channel estimates, using a first mode that does not depend on channel estimates for unreliable conditions and a second mode that depends on channel estimates for reliable conditions, with the wireless communication device or base station generating channel quality information using receiver performance data and cumulative distribution functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If link adaptation is performed based on channel quality information in rapidly changing channel conditions, then data rate adjustment responsiveness is improved, but control errors increase due to unreliable channel estimates
Solution Approach 1:
The system dynamically adjusts the channel quality metric calculation method based on channel condition stability. In stable conditions, it uses instantaneous channel estimates for rapid adaptation. In rapidly changing conditions, it switches to using statistical averages over multiple measurements, automatically adapting the metric calculation approach to match the current channel dynamics and prevent control errors
Solution Approach 2:
The system changes the parameter used for channel quality assessment based on detected channel conditions. When channel variations exceed a threshold, it transitions from using instantaneous signal-to-interference-plus-noise ratio (SINR) to using averaged SINR metrics, effectively changing the parameter representation to match the underlying channel stability characteristics
2Measurement precision
If channel quality information is determined using instantaneous channel estimates, then link adaptation accuracy is improved under stable conditions, but reliability deteriorates under fast-fading conditions
Solution Approach 1:
The system implements feedback mechanisms that monitor channel condition stability and use this information to adjust the channel quality metric calculation. By continuously monitoring channel variations and feeding this information back into the metric calculation process, the system can switch between instantaneous and averaged metrics based on actual channel behavior, ensuring reliable measurements across different fading conditions
Solution Approach 2:
The system performs preliminary assessment of channel condition stability before determining the appropriate channel quality metric. By evaluating channel variation characteristics in advance, it can pre-select the appropriate measurement approach (instantaneous vs. averaged) to avoid using unreliable instantaneous estimates during fast-fading periods
3Reliability
If output signal quality is used for channel quality information, then link adaptation performance is improved, but calculation complexity increases for non-linear receivers
Solution Approach 1:
The system extracts essential channel quality information from receiver measurements without requiring full output signal quality calculation. By taking out only the necessary components (such as instantaneous SINR or averaged quality metrics) needed for link adaptation decisions, it achieves good performance while avoiding the complex full output quality computation in non-linear receivers
Data Source
AI summary
A method and apparatus for generating channel quality information, such as may be used for transmit link adaptation, provide different operating modes, such as a first mode that may be used when propagation channel estimates are not reliable, and a second mode that may be used when the propagation channel estimates are reliable. In one or more embodiments, channel quality information is generated using receiver performance information that characterizes receiver performance in terms of a defined channel quality metric, e.g., supported data rates, for different values of receiver input signal quality over a range of propagation channel realizations. Channel quality information can be generated by selecting channel quality metrics according to receiver input signal quality and a desired probability of meeting a defined performance requirement over a range of propagation channel realizations, or by selecting channel quality metrics according to receiver input signal quality and particularized propagation channel realizations.