Multi-RIS Beam Control for Signal Blockage and Interference
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Solution Overview
Problem
Existing wireless communication systems face challenges in maintaining reliable signal strength and mitigating interference, particularly in 5G/6G communication systems using high-frequency bands like millimeter-wave, where direct-path signals are often blocked by obstacles, leading to signal blockage and interference issues.
Innovation Solution
The implementation of a method for controlling multiple reconfigurable intelligent surfaces (RISs) that receive control information to group reflecting elements and transmit signals as reflection, pass-through, or suppression beams, effectively combining reflected signals with direct-path signals to enhance received signal strength and mitigate interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple RIS nodes are deployed to overcome signal blockage, then signal reliability is improved, but system complexity increases
Solution Approach 1:
The system divides the coverage area into multiple zones, each served by a specific RIS node. The base station segments the control process by determining which RIS node serves which terminal based on angle of arrival/departure and signal quality metrics. This segmentation allows multiple RIS nodes to operate independently without full system coordination overhead.
Solution Approach 2:
Instead of having each RIS node independently select terminals, the base station performs the selection by determining the appropriate RIS node for each terminal based on channel state information. This inversion of the selection process simplifies the overall system complexity while maintaining reliability through coordinated multi-RIS operation.
2Reliability
If reflecting elements are grouped into multiple groups, then signal beamforming capability is improved, but control complexity increases
Solution Approach 1:
Reflecting elements are divided into multiple groups, with each group independently controllable. The base station determines the appropriate RIS node and reflects signals accordingly, segmenting the beamforming control into manageable units rather than controlling all elements uniformly. This enables targeted signal enhancement while reducing control complexity.
Solution Approach 2:
Different groups of reflecting elements are configured with different phase shifts and beamforming parameters optimized for specific spatial directions or terminal locations. This local quality approach allows the system to enhance signal quality for specific users without requiring complex global optimization, as each group operates with locally optimized parameters.
3Area of stationary object
If RIS nodes are used to reflect signals around obstacles, then coverage area is improved, but energy consumption increases
Solution Approach 1:
RIS nodes act as intermediaries that passively reflect signals around obstacles without requiring active signal generation or amplification. The base station determines the appropriate RIS node to serve each terminal, and the RIS node simply adjusts the phase of incident signals to redirect them toward the terminal. This intermediary approach extends coverage area while consuming minimal energy compared to active relay nodes.
Solution Approach 2:
The RIS nodes use passive reflecting elements that require minimal power consumption compared to active amplification or regeneration of signals. By using these low-power passive elements, the system can extend coverage to areas around obstacles without the high energy costs associated with active signal processing, making the coverage extension economically viable.
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 improves signal strength and reduces interference by combining reflected and direct-path signals, effectively addressing signal blockage and interference issues in mobile communication environments, including buses, aircraft, and ships, while being cost-effective and power-efficient.
Implementation Method 1
The RIS may include RIS reflecting elements. The RIS may adjust phases of the RIS reflecting elements. By adjusting the phases of the reflecting elements, the RIS can transmit reflected signals to a terminal.
Data Source
AI summary
A method of a reconfigurable intelligent surface (RIS) node may comprise: receiving, from a first transmitting node, control information for controlling the first RIS node; grouping reflecting elements of the first RIS node into at least one reflecting element group using the control information; and transmitting at least one signal incident on the at least one reflecting element group to a receiving node.