RIS Sub-Surface Configuration for NOMA Uplink Latency
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Solution Overview
Problem
In wireless communication networks, especially in IoT-enabled 5G and beyond 5G networks, the high volume of IoT device traffic leads to increased latency due to resource allocation challenges, particularly in NOMA systems where receiver complexity is high and channel conditions are difficult to maintain.
Innovation Solution
The integration of reconfigurable intelligent surfaces (RIS) with NOMA systems, where a controller dynamically configures the RIS sub-surfaces to establish indirect radiation paths between devices and the base station, ensuring that each device's received signal power is equal to or greater than the sum of lower power devices, thereby maintaining channel conditions and reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If NOMA is used to support massive connectivity and enhance spectral efficiency, then system capacity and spectral efficiency are improved, but receiver complexity increases due to successive interference cancellation requirements
Solution Approach 1:
The patent introduces an intelligent reflecting surface (IRS) as an intermediary component between devices and the base station. The IRS dynamically adjusts phase shifts and amplitude coefficients of reflected signals to create favorable channel conditions, enabling the base station to more easily separate NOMA signals through reduced interference, thus maintaining high system capacity while lowering receiver complexity requirements
Solution Approach 2:
The patent employs parameter optimization by dynamically adjusting the phase shift and amplitude coefficients of the IRS elements. By changing these parameters adaptively based on channel conditions, the system optimizes signal separation at the base station, reducing the complexity of successive interference cancellation while preserving the high spectral efficiency benefits of NOMA
2Quantity of substance
If more devices are deployed to support IoT applications, then network coverage and connectivity are improved, but latency increases due to resource allocation challenges
Solution Approach 1:
The patent implements dynamic resource allocation through the intelligent reflecting surface, which can rapidly reconfigure phase shifts and amplitude coefficients in response to changing channel conditions and device activity. This dynamic adaptation enables efficient handling of multiple IoT devices with varying latency requirements, reducing overall system latency while supporting massive device connectivity
Solution Approach 2:
The patent employs preliminary channel conditioning by using the IRS to pre-establish favorable propagation paths for multiple devices before data transmission occurs. By proactively optimizing the wireless environment through coordinated phase shifting and signal reflection, the system reduces processing delays and enables faster resource allocation for massive IoT deployments
3Power
If RIS is used to improve spectrum and energy efficiency, then signal power at the receiver is increased, but system complexity increases due to coordination and control requirements
Solution Approach 1:
The patent implements feedback mechanisms where the base station receives channel state information and performance metrics from devices, then uses this feedback to optimize the IRS configuration. This closed-loop control enables the system to maintain high signal power at receivers while managing complexity through adaptive, data-driven parameter adjustment rather than exhaustive optimization
Solution Approach 2:
The patent enables the IRS system to self-configure by leveraging channel reciprocity and local channel state information available at the IRS location. The system autonomously determines optimal phase shift and amplitude coefficients without requiring complex centralized optimization, reducing control overhead and system complexity while maintaining enhanced signal power delivery to receivers
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 solution enhances network coverage and spectral efficiency while reducing latency and complexity in resource allocation, making it suitable for massive IoT systems by leveraging the passive reflection capabilities of RIS without adding noise.
Implementation Method 1
RIS can reconfigure the wireless propagation environment and facilitate the creation of effective wireless networks through a control link to the base station (BS). In fact, each reflective element of the RIS can adjust the reflection coefficients of the incident signal, such as phase shift and amplitude, to increase the signal power at the receiver side.
Data Source
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AI summary
NOMA uplink communications via Reconfigurable Intelligent surfaces are proposed based on the determination of Reconfigurable Intelligent surfaces sub-surface configurations compatible with NOMA successive interference cancellation requirements. For multiple sets of RIS sub-surfaces, the solution extends to reconfiguring user device to sub-channel attributions either in a coordinated mode or an uncoordinated mode based on a multi-player Multi-armed Bandit framework with zero-reward.