RIS Block Precoding for Large-Array Near-Field Control
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Solution Overview
Problem
The inability to fully control the wireless environment in existing communications networks due to the large size of reconfigurable intelligent surfaces (RIS) arrays and the inapplicability of existing far-field precoding schemes, leading to reduced quality of service and increased complexity.
Innovation Solution
A method for precoding based on RIS, involving a first network device obtaining unit arrangement and block information, receiving channel feedback, determining indication information, and sending it to a second network device to adjust phase shifts, thereby dividing the RIS into groups for effective precoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large-size RIS array is deployed to control the wireless environment, then the quality of service is improved, but the precoding complexity increases and the far-field hypothesis becomes inapplicable
Solution Approach 1:
The RIS array is divided into multiple blocks, with each block containing multiple units. This segmentation allows the system to apply different precoding strategies to different blocks, reducing the overall precoding complexity while maintaining the benefits of a large RIS array for wireless environment control.
Solution Approach 2:
The patent applies the near-field hypothesis to each block individually rather than treating the entire large RIS array as a single far-field source. This local quality approach allows each block to be precoded independently using appropriate near-field models, reducing complexity while maintaining service quality.
2Device complexity
If the far-field hypothesis is used for precoding, then the precoding scheme is simple, but it becomes inapplicable when RIS array size is comparable to propagation distance
Solution Approach 1:
The patent dynamically selects between near-field and far-field hypotheses based on the specific characteristics of each RIS block and its distance to the terminal. This dynamic adaptation allows the system to maintain simplicity for far-field blocks while applying appropriate near-field models for near-field blocks, ensuring broad applicability.
Solution Approach 2:
By segmenting the RIS array into multiple blocks, the system can apply different field hypotheses to different segments based on their spatial relationships with the terminal. This segmentation enables the system to adapt to various RIS sizes and positions without being constrained by a single hypothesis.
3Adaptability or versatility
If the RIS array size is made large to improve wireless environment control, then the coverage and capability are enhanced, but the interference and complexity increase
Solution Approach 1:
The RIS array is divided into multiple blocks that can be independently controlled. This segmentation allows the system to direct beams more precisely to desired locations, reducing unintended interference in other areas while maintaining enhanced wireless environment control capability through the large number of units across multiple blocks.
Data Source
AI summary
A method for precoding based on a reconfigurable intelligence surface (RIS), performed by a first network device, includes: obtaining unit arrangement information and block information of a second network device, where the block information indicates a plurality of blocks of the second network device; receiving channel feedback information sent by a terminal, where the channel feedback information is determined by the terminal according to a reference signal sent from each block of the second network device; determining first indication information according to the channel feedback information, the unit arrangement information and the block information, where the first indication information is used to determine a phase shift matrix for the second network device; and sending the first indication information to the second network device.