Noise Rise Estimation in WCDMA Load Management
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Solution Overview
Problem
Existing load estimation methods in cellular communication systems, particularly in WCDMA, face significant uncertainties in determining the true noise floor, leading to underestimated noise rise measures and increased risks of power rushes, especially at higher loads.
Innovation Solution
A method for noise rise estimation that involves measuring received total wideband power multiple times, computing multiple estimates of the noise floor, and calculating biased noise rise measures, followed by filtering to represent long-term behavior and correcting for noise floor bias using a model, thereby improving the accuracy of noise floor estimation across a wider operating load range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing load estimation methods are used, then the method is simple, but the measurement precision of noise floor is poor leading to underestimated noise rise measures
Solution Approach 1:
The patent performs preliminary actions by measuring received total wideband power multiple times before computing the noise floor estimate. This preliminary sampling allows the system to capture the statistical distribution of power measurements, enabling more accurate noise floor estimation through subsequent analysis of the measurement history rather than relying on a single measurement.
Solution Approach 2:
The patent implements feedback by using the measured power values to compute a noise floor estimate that feeds back into the noise rise calculation. The noise floor estimate is continuously updated based on the measured power values, creating a feedback loop that refines the estimation accuracy. The biased noise rise measure is then used to correct the noise floor estimate, improving the overall measurement precision.
2Reliability
If noise rise measure is calculated using minimum power values, then the calculation is simple, but the reliability is poor at higher loads due to bias
Solution Approach 1:
The patent uses feedback by calculating a biased noise rise measure from the minimum power values and then using this biased measure to correct the noise floor estimate. The correction process feeds back the bias information into the estimation system, allowing the system to compensate for the underestimation that occurs at higher loads. This feedback mechanism significantly improves the reliability of noise rise measurement across different load conditions.
Solution Approach 2:
The patent applies parameter changes by transforming the noise floor estimate through a correction function that adjusts the estimate based on the biased noise rise measure. The correction function modifies the noise floor parameter dynamically, changing it from an underestimated value to a more accurate value. This parameter transformation enables the system to maintain measurement accuracy across a wider operating load range.
3Reliability
If power control is applied to maintain SIR, then service quality is improved, but the risk of power rush increases when capacity channel appears
Solution Approach 1:
The patent performs preliminary action by estimating the noise rise measure before scheduling enhanced uplink channels. This preliminary estimation allows the system to assess the current load conditions and capacity margin in advance. By knowing the accurate noise rise level beforehand, the system can make informed scheduling decisions that prevent power rushes before they occur, rather than reacting after they begin.
Solution Approach 2:
The patent implements feedback by continuously monitoring the noise rise measure and using this information to adjust the scheduling decisions. The feedback loop allows the system to respond to changing load conditions in real-time, adjusting the allocation of power and capacity channels to maintain cell stability. This feedback mechanism enables the system to prevent power rushes by detecting when the capacity margin is insufficient.
Data Source
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AI summary
An arrangement (90) for noise rise estimation in a wireless communication system comprises a power measuring means (45) for measuring received total wideband power. A means (52) for computing estimates of a noise floor measure bases its computation on a number of the measured received total wideband powers. A means (80) for calculating values of a biased noise rise measure bases its calculations on a number of received total wideband powers or an estimation derived therefrom and a respective one of the estimates of a noise floor measure. A means (91) for providing a measure representing a long term behaviour of the values of the biased noise rise measure is provided. A means (93) for obtaining a value of a present, unbiased noise rise measure, bases its function on the measure representing a long term behaviour of the values of the biased noise rise measure. A corresponding method is also disclosed.