RIS Numerology Adaptation Using Dynamic Cyclic Prefixes
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Solution Overview
Problem
The deployment of reconfigurable intelligent surfaces (RIS) in wireless communication systems increases delay spread, which can lead to communication inefficiencies and reduced coverage in 5G networks due to the introduction of long paths with comparable pathloss, disrupting the equilibrium in MIMO systems.
Innovation Solution
Implementing flexible cyclic prefix (CP) adaptation and subcarrier spacing (SCS) switching to mitigate the increased delay spread caused by RIS deployments, allowing for dynamic adjustment of CP length and SCS based on the presence and impact of P-MIMO.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If reconfigurable intelligent surface (RIS) is deployed to extend coverage, then coverage area is improved, but delay spread increases causing communication inefficiency
Solution Approach 1:
The patent implements dynamic cyclic prefix (CP) length adaptation based on detected RIS presence and delay spread characteristics. The system transitions from a static CP configuration to a dynamic one that adjusts CP length according to channel conditions, allowing the system to maintain optimal performance across varying coverage areas and delay spread conditions introduced by RIS deployment.
Solution Approach 2:
The patent changes the parameter of cyclic prefix length based on detected delay spread values. When RIS is detected and delay spread exceeds a threshold, the system switches to a longer CP configuration. This parameter adaptation resolves the contradiction by adjusting the temporal parameter (CP length) to compensate for the increased delay spread while maintaining the spatial benefit (coverage area) of RIS deployment.
2Reliability
If reconfigurable intelligent surface (RIS) is deployed to enhance signal propagation, then signal coverage is improved, but pathloss equilibrium in MIMO systems is disrupted
Solution Approach 1:
The patent implements a feedback mechanism where the user equipment (UE) detects RIS presence by analyzing delay spread characteristics and reports this information to the network entity. The network entity uses this feedback to determine appropriate CP length configurations and adjust MIMO transmission parameters accordingly, restoring system equilibrium while maintaining the benefits of RIS deployment.
Solution Approach 2:
The user equipment performs self-detection of RIS presence by measuring delay spread on received signals and autonomously determines when RIS is deployed in the vicinity. This self-service capability allows the UE to provide accurate channel condition information to the network without requiring complex network-side detection mechanisms, simplifying the overall system while maintaining MIMO equilibrium.
3Productivity
If flexible cyclic prefix (CP) adaptation is implemented to manage delay spread, then communication efficiency is improved, but system complexity increases
Solution Approach 1:
The patent implements partial adaptation by using a limited set of discrete CP length configurations rather than continuous adjustment. The system switches between predefined CP lengths (normal and extended) based on RIS detection, rather than implementing full continuous adaptation. This partial action approach provides sufficient performance improvement while minimizing the complexity overhead of the adaptation mechanism.
Data Source
AI summary
The present disclosure relates to numerology adaptation in the presence of passive multiple-input and multiple-output (P-MIMO) communications. In one implementation, a UE may identify a delay spread of a communication channel associated with a reconfigurable intelligent surface (RIS) deployment. The UE may further transmit, to a network entity, a measurement report including the delay spread of the communication channel. The UE may further receive, from the network entity, an indication associated with a cyclic prefix (CP) length. In another implementation, a network entity may receive, from a UE, a measurement report including a delay spread of a communication channel. The network entity may further identify a CP length associated with a RIS deployment on the communication channel. The network entity may further transmit, to the UE, an indication associated with the CP length.