Hybrid Zero-Forcing Beamforming for Multi-User Interference
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Solution Overview
Problem
Conventional millimeter-wave communication systems face limitations in multi-user environments due to the lack of suitable hybrid beamforming techniques, leading to inter-user interference and performance degradation, especially when dealing with limited channel state information and hardware constraints.
Innovation Solution
A method is introduced to configure an RF precoder using Zero-Forcing (ZF) techniques for baseband precoders to cancel inter-user interference, combined with a limited feedback mechanism for acquiring per-user channel information, allowing for efficient hybrid beamforming in multi-user environments by minimizing the Frobenius norm of the total transmit precoder and utilizing a consecutive RF precoder design to reduce computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If digital beamforming is used in multi-antenna environment, then beamforming performance is improved, but hardware complexity and RF chain requirements increase
Solution Approach 1:
The beamforming function is segmented into two parts: analog beamforming using array steering vectors for spatial direction control, and digital baseband precoding for multi-user interference management. This segmentation allows the system to achieve digital beamforming performance while using fewer RF chains, thus reducing hardware complexity.
2Device complexity
If conventional analog beamforming is used, then hardware requirements are reduced, but inter-user interference increases in multi-user environment
Solution Approach 1:
The system merges analog beamforming and digital baseband precoding into a hybrid architecture. The analog RF precoder handles spatial beam formation with array steering vectors, while the digital baseband precoder applies Zero-Forcing techniques to eliminate inter-user interference, achieving both low hardware complexity and high multi-user performance.
3Measurement precision
If full Channel State Information is assumed, then beamforming accuracy is improved, but feedback overhead and system complexity increase
Solution Approach 1:
Instead of requiring full CSI feedback, the system uses partial channel information through limited feedback mechanisms. The base station acquires essential channel characteristics needed for RF precoder configuration and baseband precoding without demanding complete channel state information from all users, thus reducing feedback overhead while maintaining sufficient beamforming accuracy.
Data Source
AI summary
Communication methods of a base station and a terminal are provided. The communication method of the base station includes receiving feedback information including ray gain information from a terminal, configuring a Radio Frequency (RF) precoder to minimize a Frobenius norm of a total transmit precoder of the base station, and configuring a baseband precoder based on Zero-Forcing (ZF). The communication method of the terminal includes receiving a pilot signal from a base station; estimating a channel of the terminal using the pilot signal; configuring ray gain information based on information of the estimated channel; and feeding back a codebook index corresponding to the ray gain information to the base station.