Hybrid Interference Alignment for Macro-Femto Base Stations
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Solution Overview
Problem
Current interference alignment schemes in wireless communication systems, particularly for macro-femto base stations, are inadequate in effectively mitigating interference due to the imbalance in the number of users served by macro and femto base stations, necessitating a hybrid approach that combines deterministic and opportunistic methods.
Innovation Solution
A hybrid interference alignment method is introduced, where macro base stations employ opportunistic schemes and femto base stations use deterministic methods to determine direction vectors for data transmission, aligning interfering signals to facilitate better cancellation by user equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional interference alignment schemes are used in macro-femto base station systems, then the system can operate with standard protocols, but interference mitigation is inadequate due to imbalance in user distribution between macro and femto base stations
Solution Approach 1:
The interference alignment scheme is segmented into two distinct components: a deterministic component that aligns interfering signals from femto base stations, and an opportunistic component that exploits channel variations in macro base stations. This segmentation allows each component to address specific aspects of the interference problem, improving overall effectiveness while adapting to the imbalanced user distribution between macro and femto networks
Solution Approach 2:
The patent combines two different interference alignment approaches (deterministic and opportunistic) into a hybrid composite scheme. The deterministic part provides structured interference alignment based on channel state information, while the opportunistic part leverages natural channel variations. This composite approach creates a more robust interference mitigation system that adapts to the heterogeneous user distribution in macro-femto networks
2Reliability
If deterministic interference alignment is applied to all base stations, then interference signals can be aligned for cancellation, but the complexity increases due to the need for precise channel state information and coordination
Solution Approach 1:
The hybrid scheme applies different interference alignment strategies to different base station types based on their local characteristics. Femto base stations, which serve fewer users in specific locations, use deterministic alignment. Macro base stations, which serve many users across wide areas, use opportunistic alignment. This local differentiation reduces overall system complexity while maintaining effective interference cancellation where most needed
3Adaptability or versatility
If opportunistic interference alignment is used for macro base stations, then the scheme adapts to channel variations, but interference alignment effectiveness is reduced due to the large number of users served
Solution Approach 1:
The system segments the interference management responsibility: macro base stations handle opportunistic alignment adapting to channel variations, while femto base stations handle deterministic alignment for precise interference cancellation. This segmentation allows each base station type to operate in its optimal regime, with macro stations providing adaptability and femto stations providing effectiveness
Data Source
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AI summary
A method, an apparatus, and a computer program product for wireless communication are provided. The apparatus is a first BS. The apparatus (BS2) determines (1102) a first channel (H1, 3) between a second BS (BS1) and a first UE (UE3) served by a third BS (BS3), determines (1104) a second channel (H2,3) between the first base station (BS2) and the first UE (UE3), and determines (1108) a first direction vector (v1) to be used by the second base station (BS1) for sending a data transmission. The apparatus transmits (1112) a set of resource blocks to a second UE (UE2) served by the first base station (BS2) with a second direction vector (v2) determined based on the first channel (H1, 3), the second channel (H2,3), and the first direction vector (v1) to be used by the second base station (BS1).