Predictive Link Adaptation for Wireless Interference
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Solution Overview
Problem
Current wireless communication systems face challenges in accurately determining link adaptation feedback due to varying interference levels caused by neighboring transmitters, leading to underserved receivers during low interference conditions.
Innovation Solution
The method involves predicting future interference conditions by signaling future transmit resource allocations from data sending nodes to receiving nodes, allowing for more accurate signal quality estimation and link adaptation, especially in high-speed packet access services like HSDPA in WCDMA networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transmit link adaptation is used to adjust data rates based on received signal quality, then data transmission efficiency is improved, but interference variations cause signal quality measurements to become inaccurate
Solution Approach 1:
The patent applies preliminary action by having transmitters signal their future transmit resource allocations (codes, frequencies, power levels) in advance of the actual transmission. This allows receivers to predict future interference conditions before making signal quality measurements, thereby resolving the contradiction between improving data transmission efficiency through link adaptation and maintaining measurement accuracy despite interference variations. The receiver uses the signaled resource allocation information to estimate what interference will be present and adjusts its signal quality assessment accordingly.
2Speed
If receivers calculate signal quality based on current interference conditions, then immediate feedback is obtained, but the feedback becomes outdated when interference conditions change
Solution Approach 1:
The patent resolves this contradiction by having transmitters provide preliminary information about their future transmit resource allocations before the actual transmission occurs. This allows receivers to calculate signal quality based on predicted future interference conditions rather than current conditions, maintaining both the speed of feedback (since calculations are still performed in real-time) and the reliability (since the measurements reflect actual future conditions rather than outdated current conditions).
Solution Approach 2:
The patent enhances the feedback mechanism by incorporating transmitter-signalized resource allocation information into the receiver's signal quality calculation process. The receiver uses this feedback loop where transmitters announce their intentions, receivers adjust measurements accordingly, and this information flows back to transmitters to refine future resource allocations. This creates a more reliable feedback system that accounts for actual interference conditions.
3Productivity
If transmitters allocate significant resources when packet data is available, then highest achievable data rates are obtained, but interference to surrounding receivers varies dramatically
Solution Approach 1:
The patent applies feedback by having receivers communicate their predicted signal quality measurements back to transmitters, which then use this information to adjust their transmit resource allocations. When receivers indicate that high interference is expected (based on neighboring transmitter activity), transmitters can scale back resource allocations to reduce interference. This feedback loop allows the system to achieve high data rates when conditions permit while automatically reducing interference when neighboring transmitters are active, resolving the contradiction between productivity and harmful interference.
Data Source
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AI summary
Method and apparatuses taught herein enable link adaptation feedback to be determined in advance for future transmit intervals, based on one or more data sending units sending indications of future transmit resource allocations, and receiving corresponding link adaptation feedback from data receiving units. Knowledge of the future transmit resource allocations enable individual data sending units to predict interference conditions for the future transmit interval, and thereby compute link adaptation feedback that takes advantage of low-interference conditions. Individual data sending units receive link adaptation feedback for the future transmit interval from the data receiving units they are supporting, and make corresponding link adaptations for the future transmit interval. Such operations are, in one or more embodiments, carried out in a Wideband Code Division Multiple Access (WCDMA), Long Term Evolution LTE), or WiMAX network, wherein the data sending units comprise radio base stations, and the data receiving units comprise wireless communication devices.