CINR Estimation in Fractional Frequency Reuse Systems
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Solution Overview
Problem
In mobile communication systems with fractional frequency reuse, estimating the carrier to interference and noise ratio (CINR) for restricted zones is challenging due to increased co-channel interference, leading to performance reduction and overhead in channel quality indicator (CQI) feedback.
Innovation Solution
A method and apparatus for estimating CINR in a mobile communication system based on fractional frequency reuse, where a base station receives CINR information from a mobile station allocated to a restricted zone, calculates the received signal power, and estimates the CINR value using the interference level for the restricted zone, reducing the overhead of CQI feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If fractional frequency reuse is applied to reduce co-channel interference in restricted zones, then interference level decreases, but CINR estimation accuracy deteriorates due to increased estimation complexity
Solution Approach 1:
The patent introduces an intermediary relationship between common zone CINR measurement and restricted zone CINR estimation. Instead of directly measuring restricted zone CINR (which is complex), the system uses common zone CINR as an intermediary parameter, combined with path loss difference calculations, to derive the restricted zone CINR. This mediator approach simplifies the estimation process while maintaining accuracy under fractional frequency reuse.
Solution Approach 2:
The patent replaces the direct measurement mechanism (mechanical approach of measuring restricted zone signals directly) with a computational substitution method. The system substitutes direct restricted zone CINR measurement with a calculation based on common zone CINR and path loss differences, thereby simplifying the measurement mechanism while accounting for fractional frequency reuse effects.
2Measurement precision
If direct CINR measurement in restricted zone is performed, then CINR estimation accuracy improves, but feedback overhead increases due to additional CQI reporting requirements
Solution Approach 1:
The patent extracts only the necessary information (common zone CINR and path loss characteristics) that is already available or easily obtainable, and uses it to derive restricted zone CINR. This extraction approach avoids the need to collect and report additional full restricted zone CINR measurements, thereby reducing feedback overhead while maintaining estimation accuracy.
Solution Approach 2:
The system enables the mobile station to self-estimate its restricted zone CINR using locally available measurements (common zone CINR) and pre-configured path loss information, without requiring additional network-side measurements or extensive feedback. This self-service mechanism reduces the burden on the feedback channel while maintaining accurate CINR estimation.
3Object-affected harmful factors
If frequency reuse factor is increased to reduce interference, then co-channel interference decreases, but system throughput is reduced due to fewer available frequency resources
Solution Approach 1:
The patent applies local quality by implementing different frequency reuse factors in different spatial zones: frequency reuse factor of 1 in common zones (cell center) for high throughput, and frequency reuse factor greater than 1 in restricted zones (cell boundary) for low interference. This localized approach allows the system to optimize both throughput and interference management simultaneously by adapting resource allocation to spatial characteristics.
Data Source
AI summary
An apparatus and method for estimating a carrier to interference and noise ratio (CINR) in a mobile communication system based on a fractional frequency reuse are provided. The method includes receiving a report on CINR information on a common zone from a mobile station (MS) allocated a restricted zone, calculating a received signal power value using a CINR value and an interference level value for the common zone of the MS, and estimating a CINR value for a restricted zone using the received signal power value of the MS and an interference level for the restricted zone.