OAM Multiplexing via Multi-UCA Basis Transformation

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Solution Overview

Problem

Existing OAM multiplexing systems using uniform circular arrays (UCAs) face challenges in efficiently utilizing two-dimensional space resources and require a large number of devices and complex calculations for signal processing, especially in MIMO transmission scenarios.

Innovation Solution

The use of a multi-UCA (M-UCA) configuration with concentrically disposed UCAs allows for basis transformation in both rotational and diameter directions, enabling multiplex transmission through independent transmission paths with reduced device requirements and calculation complexity by employing Fourier series and singular value decomposition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a single UCA is used for OAM multiplexing, then OAM modes can be generated with orthogonality in rotational direction, but two-dimensional space resources cannot be fully utilized

Engineering Contradiction:

Improvespace resource utilizationVSAvoidantenna array configuration

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Multiple UCAs are nested concentrically with different radii, where each UCA generates OAM modes with orthogonality in both rotational and diameter directions. This nested configuration enables two-dimensional space resource utilization while maintaining manageable device complexity through modular arrangement

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The system transitions from single-dimension (rotational direction only) to two-dimensional space resource utilization by adding the diameter direction dimension through multiple concentric UCAs. This enables independent transmission paths in both rotational and diameter directions, fully exploiting spatial resources

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Productivity

If MIMO signal processing is used with two-dimensional array antenna, then high resource usage efficiency is achieved, but large amount of calculation is required for signal processing

Engineering Contradiction:

Improveresource usage efficiencyVSAvoidsignal processing complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The system changes the fundamental parameters of signal processing by utilizing the inherent orthogonality of OAM modes in both rotational and diameter directions. This allows for simpler separation and demultiplexing operations compared to conventional MIMO, reducing computational complexity while maintaining high resource usage efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces complex MIMO signal processing mechanisms with OAM mode-based separation mechanisms. By using the natural orthogonality properties of OAM modes in two dimensions, the system achieves high productivity without requiring intensive matrix operations and weight multiplications associated with traditional MIMO

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If conventional UCA-based OAM multiplexing is used, then OAM modes are generated with rotational orthogonality, but device count and calculation complexity increase for MIMO scenarios

Engineering Contradiction:

Improveindependent propagation pathsVSAvoidnumber of devices and calculations

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Concentric UCAs are nested to create independent transmission paths in both rotational and diameter directions. This nested structure provides reliable independent propagation paths while avoiding the need for large numbers of separate devices and complex MIMO calculations

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

By adding the diameter direction dimension through multiple concentric UCAs, the system creates additional independent propagation paths without proportionally increasing device complexity. The two-dimensional orthogonal basis provides reliable independent paths while maintaining manageable system complexity

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP3691153B1OAM multiplexing communication system and OAM multiplexing communication method

Publication Date: 2022.06.22 NIPPON TELEGRAPH & TELEPHONE CORP

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AI summary

In an OAM multiplexing communication system that subjects a plurality of signal sequences to multiplex transmission by using an OAM mode as a base in a rotational direction dimension, a transmitting station includes a transmitting antenna using an M-UCA formed of a plurality of UCAs that are concentrically disposed, each of the UCAs having a plurality of antenna elements disposed circularly at an equal interval, and a unit performing basis transformation in each of the rotational direction dimension and a diameter direction dimension in a polar coordinate system having a center of the plurality of UCAs as an origin, and subjecting the plurality of signal sequences to multiplex transmission for each complex mode formed by a combination of different bases in each dimension. A receiving station includes a receiving antenna using an M-UCA formed of a plurality of UCAs that are concentrically disposed, and a unit receiving a signal subjected to multiplex transmission from the transmitting station, performing basis transformation in each of the rotational direction dimension and the diameter direction dimension by using the received signal, and demultiplexing the plurality of signal sequences subjected to the multiplex transmission.