Physical-Layer Symbol Phase Encryption for Wireless Air Interfaces
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Solution Overview
Problem
Wireless communication systems lack physical layer encryption, making data vulnerable to decryption by intercepting devices, especially since only user data is encrypted and not pilot symbols or synchronization symbols.
Innovation Solution
A method and apparatus that encrypts data at the physical layer by converting a bit stream into multiple symbols, shifting their phase, and modulating them with orthogonal subcarriers for transmission, with corresponding decryption on the receive side by reversing the phase shift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Layer 2 or Layer 3 encryption is used, then user data is encrypted, but the system remains vulnerable to decryption by intercepting devices and pilot symbols and synchronization symbols are not encrypted
Solution Approach 1:
The patent segments the encryption process into two layers: Layer 2/Layer 3 encryption for user data and physical layer encryption for all symbols including pilot and synchronization symbols. This segmentation allows each layer to handle specific encryption tasks, with the physical layer encryption adding an additional security layer without completely redesigning the existing encryption architecture.
Solution Approach 2:
The patent applies preliminary action by performing physical layer encryption on all symbols (including pilot and synchronization symbols) before transmission. This preliminary encryption ensures that even reference symbols are protected, and the receiving device can perform corresponding decryption operations to recover the original symbols before further processing.
2Reliability
If physical layer encryption is implemented, then security is enhanced, but device complexity and processing requirements increase
Solution Approach 1:
The patent introduces an intermediary phase shift operation as the physical layer encryption mechanism. Instead of implementing complex cryptographic algorithms at the physical layer, the system uses phase shifting as a simpler intermediary transformation that can be applied to all symbols uniformly. The receiving device applies the inverse phase shift to decrypt, avoiding the need for complex decryption algorithms while maintaining security.
Data Source
AI summary
A communication device converts a bit stream to multiple symbols and provides encryption at a physical layer by shifting a phase of each symbol of the multiple symbols to produce multiple encrypted symbols. Each encrypted symbol of the multiple encrypted symbols is modulated with an orthogonal subcarrier to produce at least one modulated subcarrier and the at least one modulated subcarrier is then transmitted via a wireless link. On a receive side, a receiving communication device receives the transmitted, encrypted symbols and provides decryption at a physical layer by shifting a phase of each encrypted symbol in correspondence with the phase used to encrypt the symbol at the transmit side.