DFT Matrix Beamforming for Flexible 5G Directional Modulation
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Solution Overview
Problem
Existing directional modulation techniques are not well-suited for dynamic 5G networks due to high complexity and fixed structures, which limit their adaptability and efficiency in providing secure communication links with flexible beam widths and multiple direction transmissions.
Innovation Solution
A low-complexity method and system using a discrete Fourier transform (DFT) matrix for generating antenna array weights, allowing for adaptive direction and beam-width assignments, enabling secure communication links and flexible beam configurations in multi-directional transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional directional modulation techniques are used, then secure communication links are provided, but the system complexity increases and adaptability to dynamic 5G networks decreases
Solution Approach 1:
The patent changes the parameter of the generation matrix from direction-specific to fixed DFT structure, allowing the same matrix to be used for all transmission directions. This parameter change reduces system complexity while maintaining security through the inherent properties of DFT-based beamforming
Solution Approach 2:
The fixed DFT generation matrix serves multiple functions: it enables directional beamforming, provides security through directional modulation, and adapts to different transmission scenarios without requiring reconfiguration. This universal structure resolves the contradiction by providing secure communication across multiple directions with a single matrix
2Ease of manufacture
If fixed structure directional modulation is used, then implementation is simplified, but flexibility in beam-width assignment and multi-direction transmission is limited
Solution Approach 1:
The patent introduces dynamic beam-width control by mapping data streams to different numbers of sub-beams based on required beam-widths. The system dynamically adjusts the beam configuration by selecting appropriate numbers of sub-beams (e.g., 1, 2, or 4 sub-beams) while using the same fixed DFT generation matrix, thus achieving both simplicity and flexibility
Solution Approach 2:
The patent segments the beamforming process into sub-beam components, where each data stream can be transmitted over multiple sub-beams with different beam-widths. This segmentation allows flexible beam-width assignment by controlling the number of sub-beams used, while the overall structure remains based on the simple fixed DFT matrix
3Reliability
If zero-forcing algorithms are used in multi-user schemes, then interference cancellation is achieved, but computational complexity increases significantly
Solution Approach 1:
The patent replaces the complex zero-forcing algorithm with a DFT-based beamforming approach. Instead of using iterative optimization algorithms to cancel interference, the system uses the orthogonal properties of DFT matrices to naturally separate user signals in the spatial domain, significantly reducing computational complexity while maintaining interference cancellation capability
Data Source
AI summary
Method and system for transmitting a directionally modulated data stream via an antenna array. A first signal processing circuitry receives a data symbol of a first data stream, maps the first data stream to a specified number of sub-beams based on a stream beam-width assignment, assigns a direction angle for transmission of the data stream, and transmits in parallel, for each of the specified number of sub-beams, an instance of the data symbol to a second signal processing circuitry. The second signal processing circuitry generates antenna array element weights based on the data symbol and a matrix having a DFT structure. The matrix is independent of the assigned direction angle. The data symbol is transmitted via the antenna array utilizing the antenna array element weights. The DFT is implemented as a fast Fourier transform. White noise is transmitted in the sub-beams beams outside the beam-width requirement of the data stream.