Subcarrier Allocation for Inter-Cell Interference Reduction
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Solution Overview
Problem
In cellular wireless communication systems, the use of the same frequency band across adjacent cells can lead to inter-cell interference, particularly at cell edges, which decreases system throughput as the number of cells increases.
Innovation Solution
A base station with a communication unit and a controller that determines the location of wireless terminals relative to cell edges and alternates between using specific subcarriers to minimize interference, employing cell center and cell edge subcarriers differently based on terminal location to manage communication effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the same frequency band is assigned to all cells, then the system throughput is maximized, but inter-cell interference occurs at cell edges
Solution Approach 1:
The frequency band is segmented into cell center subcarriers and cell edge subcarriers. Cell center subcarriers are used for terminals in the cell center region, while cell edge subcarriers are used for terminals at the cell edge. This segmentation allows different frequency resources to be allocated based on terminal location, reducing inter-cell interference at cell edges while maintaining high throughput in cell center areas.
Solution Approach 2:
Different subcarrier allocation strategies are applied to different spatial regions within the cell. Terminals in the cell center use cell center subcarriers, while terminals at the cell edge use cell edge subcarriers. This local quality differentiation ensures that each terminal receives appropriate frequency resources based on its specific location, optimizing both throughput and interference reduction.
2Object-affected harmful factors
If frequency bands are time-divided and assigned to cells with time shifts, then inter-cell interference is eliminated, but the whole throughput of the system decreases as the number of cells increases
Solution Approach 1:
Multiple cells merge and share the same frequency band simultaneously, rather than using time-division multiplexing. By combining cell center subcarriers and cell edge subcarriers within the same frequency band, the system achieves frequency-efficient resource allocation that supports more cells concurrently, thereby maintaining high whole throughput while reducing inter-cell interference through spatial differentiation.
Solution Approach 2:
The patent transitions from time-domain separation (time-division) to frequency-domain segmentation (subcarrier division). By introducing frequency dimension differentiation with cell center and cell edge subcarriers, the system enables multiple cells to operate simultaneously in the same time frame without significant inter-cell interference, thus improving whole throughput compared to time-division approaches.
3Object-affected harmful factors
If cell edge subcarriers are used for terminals at cell edges, then inter-cell interference is reduced, but the complexity of subcarrier management increases
Solution Approach 1:
The system automatically determines whether a terminal is located at the cell edge or cell center based on signal reception quality measurements. This self-service mechanism eliminates the need for manual configuration or complex external control, as the terminal or base station autonomously selects appropriate subcarriers based on measured channel conditions, thereby reducing management complexity while maintaining interference reduction benefits.
Data Source
AI summary
An aspect of the invention provides a wireless communication apparatus that includes a generator configured to generate modulated signals; a mapping unit configured to map the modulated signals on at least one subcarrier in a frequency domain, the subcarrier being in a first subcarrier group corresponding to one of a plurality of subcarrier groups, wherein frequencies of the subcarrier mapped by the mapping unit is predefined by a pattern with slot, each slot including symbols in a time domain, the predefined pattern of the frequencies of each slot depending on a base station; and a transmitter configured to transmit the modulated signals mapped by the mapping unit.