Non-repetitive Waveform Ranging Packets for Secure Channel Estimation
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Solution Overview
Problem
Wireless communication systems using predictable structures like CP-OFDM are vulnerable to adversarial attacks, leading to poor quality and service disruption, and legacy 802.11 devices may interfere with secure ranging operations.
Innovation Solution
Implementing waveforms with non-repetitive structures, such as Single Carrier Physical Layer (SC-PHY) and interpolated OFDM, that include a zero prefix and zero postfix, allowing secure channel estimation and ranging without interference from hacker devices, while being compatible with legacy 802.11 systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If predictable and repetitive structures (CP-OFDM, Golay sequences) are used in wireless communication systems, then compatibility with legacy systems and ease of operation are improved, but vulnerability to adversarial attacks and service disruption increases
Solution Approach 1:
The patent changes the fundamental parameter of waveform structure from repetitive/predictable patterns to non-repetitive/random patterns. This is achieved by using different training sequences for different devices and time slots, removing cyclic prefixes, and using non-periodic pilot signals. This parameter change resolves the contradiction by making the system immune to replay attacks while maintaining compatibility through proper packet formatting.
Solution Approach 2:
The patent introduces dynamic elements where training sequences and waveforms change over time and across different devices. Instead of static repetitive patterns, each device receives unique dynamic training sequences that are refreshed periodically. This dynamic approach prevents hackers from capturing and replaying signals, while the structured dynamic nature maintains compatibility with legacy systems.
2Reliability
If non-repetitive waveforms are used for secure channel estimation, then security against adversarial attacks is improved, but compatibility with legacy 802.11 systems and ease of operation deteriorates
Solution Approach 1:
The patent segments the waveform structure into distinct functional parts: legacy-compatible preamble sections that maintain compatibility with 802.11 systems, and secure non-repetitive training sequence sections that provide security. This segmentation allows legacy devices to recognize and respect the packet structure (deferring access based on duration fields) while the secure sections prevent adversarial attacks. The segmentation resolves the contradiction by serving both compatibility and security requirements simultaneously.
3Ease of operation
If channel estimation relies on multi-path channel estimation based on pilots with repetitive structures, then ease of operation is improved, but vulnerability to interloper transmissions and incorrect range calculations increases
Solution Approach 1:
The patent changes the parameter of pilot signal structure from repetitive periodic patterns to non-repetitive random patterns. This eliminates the ability of interloper devices to predict and inject fake pilot signals that would corrupt channel estimation. The non-repetitive pilots maintain channel estimation capability while preventing measurement corruption, resolving the contradiction between ease of operation and measurement precision.
Data Source
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AI summary
Communicating wireless devices collaborate and utilize waveforms to enable secure channel estimation. To protect against a repetitive replay attack, some embodiments include Single Carrier Physical Layer (SC-PHY) waveforms and/or interpolated OFDM waveforms that do not include a repeatable or predictable structure. The waveforms are transmitted in ranging packet structures that are compatible with legacy 802.11 technologies that do not utilize secure channel estimation. The ranging packets are received in combination with the information previously exchanged to enable the receiving wireless system to securely determine a channel estimate (e.g., determine a channel estimate without an interloper transmission that is not an authentic first arrival path in a multi-path channel between the wireless systems). Thus, one or both of the wireless systems can estimate the distance between them (or range). Devices utilizing legacy 802.11 technologies may receive the ranging packet structures and determine durations for deferring access to the channel.