Mobile Channel Noise Estimation via Multipath Interference Subtraction
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Solution Overview
Problem
Conventional channel estimation methods in mobile communication systems inaccurately estimate noise power due to interference from multiple paths, degrading receiver performance, especially when using equalizers or conventional finger combining schemes.
Innovation Solution
A method and apparatus for channel estimation in mobile communication systems that utilize a noise estimation unit to select a scheme based on the channel environment, summing unused Orthogonal Variables Spreading Factor (OVSF) powers and Received Signal Strength Indication (RSSI) values to accurately estimate thermal noise power, thereby reducing multipath interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional de-spreading scheme using OVSF is employed to estimate noise power, then the noise power can be obtained by squaring and adding I/Q components, but the estimation includes other path interference power from multiple paths which degrades accuracy
Solution Approach 1:
The patent extracts only the thermal noise component from the total measured power by subtracting the estimated multipath interference power. The noise estimation unit separates the desired noise power from the harmful multipath interference using the formula: noise power = total measured power - multipath interference power, thereby obtaining accurate thermal noise estimation free from interference contamination
Solution Approach 2:
The patent introduces channel estimation values as an intermediary to estimate and remove multipath interference power. The channel estimation unit provides channel characteristics that enable the noise estimation unit to calculate and subtract the interference component, serving as a mediator between the received signal and the final noise power estimation
2Ease of operation
If noise power is estimated using unused OVSF in conventional scheme, then the estimation can be obtained, but the receiver performance is degraded when equalizer scheme is used
Solution Approach 1:
The patent implements a feedback mechanism where the channel estimation unit continuously provides channel state information to the noise estimation unit, which then adjusts its estimation approach. The noise estimation results are fed back to improve equalizer performance, creating a closed-loop system that adapts to changing channel conditions and maintains optimal receiver performance
Solution Approach 2:
The patent changes the estimation parameters by using channel estimation values and multipath interference power calculations instead of directly using unused OVSF power. This parameter transformation allows the system to achieve accurate noise estimation that is compatible with equalizer schemes, improving receiver reliability while maintaining ease of operation
Data Source
AI summary
An apparatus and a method for estimating a channel in a mobile communication system are provided. The apparatus includes a channel estimation unit for determining a channel estimation value using a channel power for each of a plurality of fingers, and a noise estimation unit for selecting a scheme for estimating a thermal noise power according to a channel environment among schemes for determining a plurality of thermal noise powers, and for estimating a noise using the channel estimation value in the selected scheme.