CINR Compensation for Accurate Channel Information in Multi-Cell Systems
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Solution Overview
Problem
In multi-cell or multi-sector radio communication systems, mobile stations face challenges in accurately estimating downlink channels and measuring Carrier to Interference and Noise Ratio (CINR) due to insufficient pilots and interference from adjacent cells or sectors, leading to erroneous Channel Quality Information (CQI) reports, which affects scheduling and resource allocation.
Innovation Solution
An apparatus and method that include a CINR checking unit, a loading checking unit, and a CINR compensation unit to calculate an effective loading factor from adjacent cells or sectors, compensating the CINR to accurately determine channel information for resource allocation and scheduling control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the MS measures CINR by using all pilots in a DL sub-frame, then the MS can perform channel estimation, but the CINR measurement becomes erroneous due to interference from adjacent cells or sectors
Solution Approach 1:
The patent extracts only the necessary pilot signals from the set of all pilots in the DL sub-frame. Specifically, it identifies and uses only the pilot signals that are not overlapped with or interfered by adjacent cells or sectors, thereby removing harmful interference sources while retaining useful channel estimation capability
Solution Approach 2:
The patent applies different quality criteria to different pilot signals based on their spatial location and interference characteristics. Pilot signals in regions with high interference from adjacent cells are excluded, while pilot signals in cleaner regions are used for accurate CINR measurement, creating a non-uniform selection based on local quality
2Measurement precision
If the MS measures CINR by using pilots located in allocation region for the MS, then the MS can perform channel estimation, but the channel estimation becomes wrong due to insufficient pilots
Solution Approach 1:
The patent makes the selected pilot signals serve multiple functions simultaneously: they are used for both channel estimation and accurate CINR measurement. By carefully selecting pilots that are not interfered with, the system achieves multi-functionality that resolves the contradiction between having enough pilots and maintaining measurement accuracy
3Productivity
If the scheduler performs scheduling based on erroneous CINR, then the scheduling can be performed, but resource allocation becomes inefficient and transmission rate decreases
Solution Approach 1:
The patent implements a feedback mechanism where the MS reports accurate CINR values (after excluding interfered pilots) to the BS, and the BS uses this feedback information to perform accurate scheduling. This feedback loop ensures that scheduling decisions are based on reliable channel quality information, improving both transmission rate and scheduling accuracy
Data Source
AI summary
The present invention relates to an apparatus and to a method for acquiring downlink channel information in a radio communication system having a multi-cell/sector structure, comprising receiving channel quality information of a mobile station and loading information of cells/sectors adjacent to the mobile station, checking the carrier to interference and noise ratio (CINR) contained in the channel quality information, checking the average loading factor of the adjacent cells/sectors contained in the loading information, summing the average loading factors for each of the adjacent cells/sectors to calculate an effective loading factor, and compensating for the CINR with the effective loading factor to acquire channel information of the base station.