Inter-cell Interference Nulling via PMI Feedback
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Solution Overview
Problem
In next-generation mobile communication systems with reduced cell coverage, users at the edge of cells experience interference from adjacent cells, leading to unpredictable Quality of Service (QoS) due to closer inter-cell distances, and existing solutions like IEEE 802.16m and LTE-Advanced face challenges in efficiently managing inter-cell interference.
Innovation Solution
A method where a mobile station determines a Precoding Matrix Index (PMI) based on interference channels between adjacent base stations and feeds back Channel State Information (CSI) and PMI to the serving base station, allowing for reduced feedback overhead and improved precoding vector design to align interference signals in null spaces, thereby enhancing Signal to Interference plus Noise Ratio (SINR).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If inter-cell distance is reduced to prevent cell coverage reduction, then cell coverage is maintained, but inter-cell interference increases and QoS cannot be guaranteed
Solution Approach 1:
The patent segments the interference management into two parts: (1) mobile station determines PMI based on interference channels from adjacent cells, and (2) serving base station uses this PMI along with CSI to design precoding vectors that align interference in null spaces. This segmentation allows independent optimization of interference cancellation without requiring full joint processing of all cells
Solution Approach 2:
The mobile station feeds back both CSI for the serving cell and PMI determined from interference channels to the serving base station. This feedback mechanism enables the base station to obtain interference channel information without direct measurement, reducing overhead while maintaining effective interference cancellation capability
2Object-affected harmful factors
If joint processing technology is used to manage inter-cell interference, then interference control improves, but data exchange complexity and feedback overhead increase
Solution Approach 1:
The patent extracts only the essential interference channel information needed for precoding design by having the mobile station determine PMI based on interference channels and feed back only this PMI along with serving cell CSI. This extraction approach avoids the need for complete joint processing data exchange while maintaining effective interference management
Solution Approach 2:
Instead of implementing full joint processing that would require complete channel state information from all cells, the patent uses partial action by utilizing only the PMI derived from interference channels and serving cell CSI at the base station. This partial information set is sufficient for designing precoding vectors that achieve interference cancellation in null spaces
Data Source
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AI summary
The invention relates to a base station in a wireless communication system comprising a mobile station and the base station. The base station comprises a CSI receiving unit configured to receive Channel State Information (CSI) of a first channel between the base station and a first mobile station from the first mobile station, the first mobile station being located in a cell where the base station belongs, a PMI receiving unit configured to receive a Precoding Matrix Index (PMI) which is determined by a second mobile station based on a second channel between the base station and the second mobile station, the second mobile station being located in an adjacent cell and a precoder configured to design a precoding vector based on the CSI and the PMI.