Unitary Braid Divisional Multiplexing for Wireless Signal Security
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Solution Overview
Problem
Existing wireless communication systems lack a secure and power-efficient approach for transmitting signals, particularly in multiple access communications where multiple user devices share the same channel, and current methods like OFDM do not address physical layer security or handle high peak-to-average-power ratios effectively.
Innovation Solution
The implementation of Unitary Braid Divisional Multiplexing (UBDM) with Physical Layer Security (PLS) using a generalized version of OFDM that applies arbitrary transformations, such as unitary, equiangular tight frame (ETF), or nearly equiangular tight frame (NETF) transformations to encode signals, reducing Peak-to-Average-Power-Ratio (PAPR) and enhancing security through code division multiplexing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If OFDM is used for wireless communication, then signal transmission capability is improved, but Peak-to-Average-Power-Ratio becomes very high requiring transmitters that can handle high PAPR
Solution Approach 1:
The patent applies unitary transformations (such as DFT, FFT, or other unitary matrices) to transform the signal parameters before transmission. This transformation changes the signal structure to achieve lower PAPR while maintaining transmission capability, directly addressing the contradiction between signal transmission performance and power efficiency
Solution Approach 2:
The patent replaces traditional mechanical/power-intensive transmission methods with mathematical transformations (unitary transformations). Instead of relying on high-power transmitters to handle PAPR, the system uses mathematical operations to reshape the signal, substituting computational complexity for physical power handling requirements
2Reliability
If OFDM is used for signal communication, then coping with severe channel conditions is improved, but physical layer security is not addressed
Solution Approach 1:
The patent applies different unitary transformations to different signal components or users, creating localized security properties. Each user or signal stream can have its own transformation applied, providing security at the local signal level while maintaining overall system reliability
Solution Approach 2:
The unitary transformation acts as an intermediary between the original signal and the transmitted signal. This intermediary operation embeds security properties into the signal structure itself, allowing reliable transmission through severe channels while simultaneously providing physical layer security
3Adaptability or versatility
If arbitrary transformations are applied to encode signals, then code division multiplexing capability is enhanced, but device complexity increases
Solution Approach 1:
The patent uses unitary transformations that serve multiple functions simultaneously: they provide code division multiplexing capability, maintain signal energy preservation, enable easy inversion at the receiver, and provide security. This multi-functionality increases adaptability while managing device complexity through mathematical elegance rather than physical complexity
Data Source
AI summary
A system includes first and second sets of communication devices. A processor coupled to the first set of communication devices produces a first encoded vector and transmits the first encoded vector to the second set of communication devices via a communication channel that applies a channel transformation to the first encoded vector during transmission. A processor coupled to the second set of communication devices receives the transformed signal, detects an effective channel thereof, and identifies left and right singular vectors of the effective channel. A precoding matrix is selected from a codebook of unitary matrices based on a message, and a second encoded vector is produced based on a second known vector, the precoding matrix, a complex conjugate of the left singular vectors, and the right singular vectors. The second encoded vector is sent to the first set of communication devices for identification of the message.