Secure Ranging Packets Using Asymmetric Waveforms
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Solution Overview
Problem
Wireless communication systems using predictable structures like CP-OFDM and Golay sequences are vulnerable to adversarial attacks that disrupt secure ranging by tampering with time of arrival measurements, and legacy 802.11 devices may interfere with secure ranging communications.
Innovation Solution
Implementing waveforms without repetitive structures, such as Single Carrier Physical Layer (SC-PHY) and interpolated OFDM waveforms, that include a zero prefix and zero postfix, allowing secure channel estimation and compatibility with legacy 802.11 systems, enabling secure ranging packet structures that prevent interloper transmissions and ensure accurate distance calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If predictable and repetitive structures (CP-OFDM, Golay sequences) are used for wireless communication, then compatibility with legacy systems and ease of implementation are improved, but vulnerability to adversarial attacks and security issues worsen
Solution Approach 1:
The patent applies asymmetry by using asymmetric training sequences where the transmitted training sequence is not equal to its conjugate reverse, breaking the symmetry that hackers exploit. This asymmetric design makes it computationally infeasible for attackers to perform brute-force attacks on the training sequence while maintaining compatibility with legacy 802.11 systems through the use of standardized preamble structures.
Solution Approach 2:
The patent changes key parameters of the training sequence including using non-Golay sequences, implementing cyclic shifts rather than simple repetitions, and using different root sequences for different spatial streams. These parameter changes maintain the functional requirements for channel estimation while eliminating the predictable patterns that vulnerability to adversarial attacks.
2Ease of operation
If cyclic prefix OFDM structures are used for wireless transmission, then ease of operation and implementation are improved, but susceptibility to interloper transmissions and service disruption worsens
Solution Approach 1:
The patent applies preliminary action by implementing security measures at the training sequence level before actual data transmission begins. The asymmetric training sequences are established in the preamble phase, allowing the system to detect and reject interloper transmissions early in the communication process before significant data exchange occurs, thereby preventing service disruption.
Solution Approach 2:
The patent implements feedback mechanisms where the receiving device verifies the authenticity of training sequences by checking against expected asymmetric patterns. When interloper transmissions are detected through failed verification, the system provides feedback to reject the transmission and maintain secure ranging operations, preserving the ease of operation while blocking harmful factors.
3Reliability
If secure waveforms without repetitive structures are implemented, then security against adversarial attacks is improved, but compatibility with legacy 802.11 systems and ease of operation worsen
Solution Approach 1:
The patent applies universality by designing a ranging packet structure that serves multiple functions: it provides secure asymmetric training sequences for resistance to adversarial attacks, while simultaneously maintaining compatibility with legacy 802.11 systems through standardized preamble formats. This multi-functional design allows the same packet structure to achieve both security enhancement and legacy compatibility.
Solution Approach 2:
The patent uses the legacy 802.11 preamble as an intermediary layer that bridges secure new technology and existing legacy systems. The asymmetric training sequences are embedded within the standardized preamble structure, allowing legacy devices to recognize and process the packets while secure ranging operations benefit from the enhanced security of non-repetitive sequences.
Data Source
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.