Two-Loop Power Control Adjusting Target SIR via Hard Metric Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power control methods in communications systems, such as WCDMA, face low power control accuracy, which prevents the system from correctly converging to the required target quality due to reliance on target soft metrics that are not accurately adjusted by hard metrics.
Innovation Solution
The method involves performing first outer loop power control based on actual and preset hard metrics to adjust target soft metrics, ensuring accurate convergence of target hard metrics by using a two-loop power control system that includes outer and inner loop power control, with adjustments made by a radio network controller to achieve the desired signal-to-interference ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If outer loop power control adjusts target SIR based on soft metric (BER) only, then the control process is simple, but power control accuracy is low and target quality cannot be correctly converged
Solution Approach 1:
The power control system is segmented into two independent outer loop controllers: the first outer loop power control adjusts target SIR based on hard metric (BLER), and the second outer loop power control adjusts target SIR based on soft metric (BER). This segmentation allows each controller to specialize in one metric type, improving overall power control accuracy while maintaining manageable complexity through modular design
Solution Approach 2:
The first outer loop power control acts as an intermediary that adjusts the target soft metric (target BER) based on hard metric feedback (actual BLER). This intermediary controller bridges the gap between hard quality requirements and soft metric-based control, enabling accurate convergence to target quality by translating hard metric performance into appropriate soft metric adjustments
2Ease of manufacture
If single outer loop power control uses only soft metric for adjustment, then implementation is straightforward, but convergence to target quality is inaccurate
Solution Approach 1:
The single outer loop is segmented into two sequential outer loop controllers. The first outer loop handles hard metric-based adjustments (BLER to target BER), and the second outer loop handles soft metric-based adjustments (target BER to target SIR). This segmentation maintains implementation straightforwardness through clear separation of concerns while dramatically improving target quality convergence reliability
Solution Approach 2:
The first outer loop power control performs preliminary action by pre-adjusting the target soft metric (target BER) based on hard metric performance before the second outer loop uses this adjusted target for SIR control. This preliminary adjustment ensures that the soft metric target is already aligned with hard quality requirements, enabling reliable convergence to target quality
Data Source
AI summary
A power control method, apparatus, and system is described. First outer loop power control is performed according to an actual hard metric and a preset target hard metric to adjust a target soft metric required by second outer loop power control, to obtain an adjusted target soft metric. Therefore, this ensures that when the adjusted target soft metric is converged, the target hard metric can be correctly converged to achieve target quality required by a system.