RIS Group Indexing for Reliable Quadrature Reflection Modulation
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Solution Overview
Problem
Existing RIS-based communication systems face challenges in controlling reconfigurable intelligent surfaces (RIS) for efficient data transmission and reception, particularly due to the passive nature of RIS and the lack of conventional RF chains, which complicates data aggregation and modulation.
Innovation Solution
Employing a quadrature reflection modulation (QRM) scheme that partitions RIS elements into groups configured in either quadrature or in-phase modes, using a predefined set of patterns to transmit data efficiently, and implementing an effective indexing scheme to maximize symbol separation and reduce channel state information overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RIS elements are partitioned into L groups with each group configurable in Quadrature or In-Phase mode, then data transmission capacity is improved, but device complexity increases due to pattern selection and control requirements
Solution Approach 1:
The RIS is divided into L groups of elements, where each group can be independently configured in either Quadrature mode or In-Phase mode. This segmentation allows the system to achieve higher data transmission capacity by creating multiple orthogonal signal dimensions, while the grouped structure simplifies the control complexity compared to controlling each element individually.
Solution Approach 2:
The system changes the operational parameters of RIS groups by switching between Quadrature mode (90-degree phase shift) and In-Phase mode (0-degree phase shift). This parameter change enables the system to create orthogonal signal spaces for data transmission, increasing capacity while maintaining manageable control through discrete mode selection rather than continuous parameter adjustment.
2Reliability
If a predefined set of patterns is used to select from all possible patterns for L groups, then reliability is improved through optimized symbol separation, but the quantity of usable transmission modes is reduced
Solution Approach 1:
Instead of using all possible patterns for L groups (which would be 2^L patterns), the system selects a predefined subset of patterns that provides sufficient symbol separation for reliable communication. This partial action approach ensures reliability by using only well-separated patterns while avoiding the complexity of managing all possible patterns.
Solution Approach 2:
The predefined set of patterns is designed to ensure that all selected patterns provide equivalent and optimal symbol separation in the signal space. This equipotentiality ensures that any pattern from the predefined set yields the same reliability performance, allowing the system to maximize transmission modes within the predefined set while maintaining uniform reliability across all modes.
3Reliability
If QRM symbols are optimized for maximum separation, then error rates are reduced, but channel state information overhead increases
Solution Approach 1:
The system segments the RIS into L groups that can be independently controlled in Quadrature or In-Phase modes. This segmentation creates L orthogonal dimensions for data transmission, allowing maximum symbol separation and minimized error rates. The grouped structure enables efficient channel state information management by reducing the overhead required to describe the configuration of each group.
Data Source
AI summary
Controller devices and control methods are provided. At the transmitting side, a data portion is obtained and a RIS is used, including a plurality of elements, to transmit the data portion. The plurality of elements are partitioned into L groups. For each group, all elements of the group are configurable in the same one of a Quadrature mode or an In-Phase mode. A pattern is selected out of a predefined set of patterns according to the data and a predefined correspondence between group patterns and respective data portions which is a subset of all possible patterns for the L groups. Each pattern in the predefined set of patterns defines for each of the L groups whether the group is configured in the Quadrature mode or in the In-phase mode. The data portion is transmitted according to the selected pattern. The corresponding demodulation is provided for the receiving side.