Hybrid Beamforming for Inter-Beam Interference in 5G MIMO
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Solution Overview
Problem
In multi-antenna 5G communication systems, particularly in millimeter wave frequency bands, forming multiple beams simultaneously leads to inter-beam interference, making it difficult to achieve desired data rates, especially in environments where channel measurement-purpose pilot symbols are not available.
Innovation Solution
A method for configuring analog beam patterns to minimize inter-beam interference by determining channel matrices based on beam direction information and antenna element configurations, using a digital front end to remove interference signals without additional complexity, and employing hybrid beamforming to optimize signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple beams are formed simultaneously to multiple terminals, then the total throughput is increased, but inter-beam interference occurs making it difficult to achieve desired data rates
Solution Approach 1:
The patent changes the phase parameters of antenna elements to create directional beams. By adjusting phase shifters in the analog beamforming network, beams are steered toward specific terminals while maintaining control over interference patterns through parameter optimization
Solution Approach 2:
The patent applies different phase and amplitude weights to different antenna elements based on their spatial locations. This creates locally optimized beam patterns where each antenna element contributes differently to the overall beamforming pattern, enabling simultaneous service to multiple terminals with reduced interference
2Productivity
If channel measurement-purpose pilot symbols are not used, then transmission resources are saved, but channel estimation becomes difficult in multi-antenna systems
Solution Approach 1:
The patent enables the system to estimate channels using existing data transmission signals rather than requiring separate pilot symbols. The channel estimation is performed self-service style by utilizing the uplink data signals that are already being transmitted for communication purposes
Solution Approach 2:
The patent makes the data transmission signals serve dual purposes: both for actual data communication and for channel estimation. This multi-functionality eliminates the need for separate pilot symbols while maintaining accurate channel knowledge for beamforming operations
3Loss of energy
If analog beamforming is used in millimeter wave frequency bands, then propagation loss is decreased and transmission distance is increased, but device complexity increases due to multiple antenna elements
Solution Approach 1:
The patent segments the beamforming function into two parts: analog beamforming for directional signal steering and digital signal processing for interference management. This segmentation allows the system to leverage analog beamforming's high gain properties while using digital processing to handle the complexity of multi-terminal interference
Solution Approach 2:
The patent introduces a digital front-end processing stage as an intermediary between the analog beamforming network and the data transmission. This intermediary layer provides channel estimation and signal processing capabilities that simplify the overall system management while maintaining the benefits of analog beamforming
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces inter-beam interference and enhances data rate capabilities in multi-user MIMO environments without requiring channel measurement-purpose pilot symbols, improving the efficiency of signal transmission and reception.
Implementation Method 1
a phase shifter based on a channel matrix determined by a preferred beam index
Implementation Method 2
beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, analog beam forming, and large scale antenna techniques
Data Source
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AI summary
Disclosed are a communication technique for merging, with IoT technology, a 5G communication system for supporting a data transmission rate higher than that of a 4G system, and a system therefor. The disclosure can be applied to an intelligent service (for example, smart home, smart building, smart city, smart car or connected car, health care, digital education, retail, security and safety-related services, and the like) on the basis of 5G communication technology and IoT-related technology. According to an embodiment of the present invention, a method by which a base station transmits a signal in a wireless communication system comprises the steps of: transmitting, to a terminal through at least one beam, at least one beam index including information on beam direction; receiving, from the terminal, a preferred beam index determined by the terminal; determining a channel matrix between the base station and the terminal on the basis of the preferred beam index; and allowing the base station to transmit a signal to the terminal on the basis of the channel matrix. The study has been performed under the support of the "Government-wide Giga KOREA Business" of the Ministry of Science, ICT and Future Planning.