RIS-Assisted Beam Selection for mmWave Shadow Areas
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Solution Overview
Problem
There is a challenge in efficiently managing beams in wireless communication systems, particularly in eliminating shadow areas in high-frequency environments like the mmWave band, where traditional methods struggle to provide reliable coverage.
Innovation Solution
The proposed solution involves a method where a base station uses beamforming to transmit control information and synchronization signals to a terminal located in a shadow area through a Reconfigurable Intelligent Surface (RIS). The method includes transmitting control information to an RIS controller, synchronizing signals with multiple beams for various reflection patterns, measuring signal strength, selecting optimal beams and reflection patterns, and generating a codebook for the RIS based on these selections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional transmission methods are used in high-frequency environments, then device complexity is reduced, but coverage reliability deteriorates due to shadow areas
Solution Approach 1:
The patent introduces a Reconfigurable Intelligent Surface (RIS) as an intermediary component between the base station and terminals in shadow areas. The RIS reflects and redirects signals to reach terminals that would otherwise be in coverage holes, thereby improving coverage reliability without requiring complex changes to the base station's core transmission system.
Solution Approach 2:
The patent segments the coverage area into different zones (line-of-sight areas and shadow areas) and applies different transmission strategies for each. Beamforming is used for direct transmission in line-of-sight areas, while RIS-assisted reflection is deployed for shadow areas, allowing optimized handling of each segment's specific requirements.
2Area of stationary object
If beamforming with multiple beams is implemented, then coverage area is improved, but device complexity increases due to need for multiple synchronization signals
Solution Approach 1:
The patent segments synchronization signals into different types (first synchronization signal for initial access, second synchronization signal for beam management) and transmits them through different paths (direct and RIS-reflected). This segmentation allows the system to manage multiple beams and large coverage areas while maintaining organized signal structures and reducing management complexity.
3Reliability
If RIS is deployed to eliminate shadow areas, then coverage reliability is improved, but device complexity increases due to RIS controller requirements
Solution Approach 1:
The patent implements a self-service mechanism where the RIS controller autonomously selects appropriate reflection patterns based on feedback information from terminals about signal quality and beam conditions. This self-service capability reduces the need for complex centralized control and simplifies the overall RIS control system while maintaining effective shadow area coverage.
4Reliability
If multiple reflection patterns are controlled, then signal coverage in shadow areas is improved, but loss of time increases due to measurement and selection processes
Solution Approach 1:
The patent implements preliminary action by having the base station transmit beam information and synchronization signals before actual data transmission. Terminals perform measurements and report feedback in advance, allowing the RIS controller to pre-select optimal reflection patterns. This preliminary preparation reduces the time required for beam selection during actual transmission, thereby reducing overall time loss while maintaining reliable signal reach in shadow areas.
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 enables efficient communication between a base station and a terminal in a shadow area by optimizing beamforming and reflection patterns, thereby improving coverage and reducing signal loss in high-frequency environments.
Implementation Method 1
transmitting synchronization signals corresponding to a plurality of beams of the base station for each of the plurality of reflection patterns controlled based on the control information to a terminal located at a shadow area via the RIS
Implementation Method 2
a base station uses beamforming to transmit control information and synchronization signals to a terminal located in a shadow area through a Reconfigurable Intelligent Surface (RIS)
Data Source
AI summary
Disclosed is a method of a base station that supports beamforming in a wireless communication system, the method comprising the steps of: transmitting, to an RC, control information for controlling a plurality of reflective patterns of an RIS; transmitting synchronizing signals corresponding to a plurality of beams of the base station via the RIS to a terminal positioned in a shadow region, wherein the synchronizing signals are sent for each of the plurality of reflective patterns controlled on the basis of the control information; receiving, from the terminal, measurement reports containing measurement results of the intensities of the synchronizing signals corresponding to the plurality of beams of the base station, wherein the measurement reports are received for each of the plurality of reflective patterns; selecting at least one of the plurality of beams and at least one of the plurality of reflective patterns as an optimal beam and an optimal reflective pattern for the shadow region on the basis of the measurement results contained in the measurement reports; and generating a code book for the RIS on the basis of the selected optimal reflective pattern for the shadow region.