Predictive Link Adaptation for Inter-Cell Interference
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Solution Overview
Problem
Existing link adaptation methods in LTE networks fail to accurately capture rapid variations in signal quality due to inter-cell interference and own cell signal variations, especially when user equipment (UE) is moving, leading to suboptimal throughput and channel quality prediction errors.
Innovation Solution
A method and radio network node that predict the future position of the UE based on its current position, speed, and direction, estimating the Signal to Interference and Noise ratio (SINR) using path-loss values and transmission power of interfering cells to determine link adaptation parameters for improved channel quality estimation and scheduling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If link adaptation parameters are determined based on current channel quality measurements, then the system maintains stability in parameter selection, but it fails to capture rapid variations in signal quality when UE is moving, leading to suboptimal throughput
Solution Approach 1:
The system performs preliminary actions by predicting the future position of the UE based on current position, speed, and direction. Path-loss values are pre-calculated for the predicted future position, and link adaptation parameters are determined in advance for the upcoming scheduling occasion. This allows the system to proactively adapt to channel conditions before the UE actually moves into the predicted position, capturing rapid signal quality variations that would otherwise be missed by reactive measurement-based approaches.
2Device complexity
If the system uses feedback timing and scheduling timing delays for link adaptation, then it reduces processing complexity and overhead, but it results in using outdated channel quality measurements that do not reflect current conditions
Solution Approach 1:
The system performs preliminary calculations of path-loss values for the predicted future position of the UE before the actual scheduling occasion. By using the current position, speed, and direction to forecast future channel conditions, the system eliminates the need to wait for delayed feedback measurements. This preliminary action allows link adaptation parameters to be determined based on predicted current conditions rather than outdated historical measurements, effectively removing the time loss introduced by feedback delays while maintaining reasonable processing complexity.
3Reliability
If link adaptation parameters are adjusted conservatively to maintain reliability, then the system avoids rapid fluctuations in transmission quality, but it prevents timely recovery from channel quality drops and reduces throughput
Solution Approach 1:
The system performs preliminary determination of link adaptation parameters for the predicted future position before actual transmission occurs. By calculating path-loss values and determining appropriate modulation and coding schemes in advance based on predicted channel conditions, the system can proactively adjust parameters to match upcoming signal quality. This allows timely recovery from channel quality drops without conservative delays, as the system is already prepared with appropriate parameters for the predicted future state, thereby maintaining both reliability and throughput.
Data Source
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AI summary
The present invention relates to a method for determining link adaptation parameters for a wireless device. The method is performed in a first radio network node of a wireless communication system. The first radio network node hosts a first cell serving the wireless device. The wireless device is interfered by a second cell. The method comprises predicting (410) a future position of the wireless device. The method also comprises estimating (420) a first radio channel quality value for the wireless device in the predicted future position, based on: pathloss values related to the wireless device in the predicted future position for the first and the second cell respectively; and a transmission power of the second cell. The method further comprises determining (430) link adaptation parameters for the scheduling of the wireless device in the future position using the estimated first radio channel quality value.