RIS Codebook Design for Beam Squint and Feedback Overhead
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Solution Overview
Problem
Existing communication systems face challenges in maximizing channel capacity due to varying channel conditions, particularly in areas with shadowing, and current codebook designs in 5G and 6G terahertz communication systems are inadequate for handling beam squint phenomena with large numbers of antennas and wide frequency bands.
Innovation Solution
A method and apparatus for codebook design in a communication system using a reconfigurable intelligent surface (RIS) that estimates and adjusts phase characteristics of RIS elements, employing a codebook generation technique to optimize signal reflection and minimize beam squint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the base station quantizes all 360 degrees of phase to control the RIS, then the phase control precision is improved, but the radio resource consumption increases and becomes challenging
Solution Approach 1:
The patent applies partial action by quantizing only the necessary phase range rather than all 360 degrees. The base station determines a reduced phase quantization range based on channel conditions and RIS characteristics, achieving adequate control precision while consuming fewer radio resources for feedback transmission
Solution Approach 2:
The patent changes the parameter of phase quantization from a fixed 360-degree range to a dynamic reduced range. The base station adjusts the phase quantization parameters based on channel state information and communication requirements, optimizing the balance between control precision and resource consumption
2Weight of moving object
If the RIS incorporates passive elements, then the device size and weight are reduced, but the power adjustment capability is limited
Solution Approach 1:
The patent replaces active power adjustment mechanisms with passive electromagnetic field manipulation. The RIS uses passive reflecting elements that manipulate signal phases and directions through electromagnetic induction rather than active power amplification, achieving beamforming without requiring power-intensive components
Solution Approach 2:
The patent introduces the passive RIS as an intermediary between the base station and terminal. The RIS reflects and redirects signals using passive elements, mediating the communication path to overcome shadowing and improve coverage without requiring active power generation or amplification capabilities
3Quantity of substance
If the codebook uses a subset of representative phase values, then the radio resource consumption is reduced, but the phase control precision deteriorates
Solution Approach 1:
The patent dynamically changes the phase quantization parameters based on communication requirements and channel conditions. The base station determines an optimized phase quantization range and step size that achieves adequate precision while minimizing the codebook size and feedback overhead, adapting to different operational scenarios
Solution Approach 2:
The patent applies partial quantization by focusing phase resolution only where needed within a reduced phase range. Rather than uniformly quantizing all 360 degrees, the system applies finer quantization to critical phase regions while using coarser quantization elsewhere, reducing overall resource consumption while maintaining necessary precision
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
Improves network performance by enhancing signal transmission and reception, particularly in environments with obstacles, and addresses the limitations of existing codebook designs in 5G and 6G systems.
Implementation Method 1
The RIS has the ability to reflect input signals in a desired direction. It comprises multiple elements, and can adjust the phases of the signals based on these elements to achieve the desired signal reflection.
Implementation Method 2
To steer signals effectively, the RIS's controller adjusts the impedances of its elements, thereby altering the phases of the signals. Beamforming is achieved by the RIS using phase information transmitted from a base station.
Data Source
AI summary
Disclosed are a method and an apparatus for codebook design in a communication system. A method of a base station may comprise: transmitting a pilot signal to a terminal by using a reconfigurable intelligent surface (RIS); receiving, from the terminal, channel information measured based on the pilot signal; estimating characteristics of elements of the RIS based on the channel information; generating a codebook based on the estimated characteristics of the elements; and transmitting the codebook to a controller of the RIS.