Wireless Range Determination via Symbol Pattern Correlation

Solution Overview

Problem

Existing wireless communication systems, such as IEEE 802.15.4, are vulnerable to spoofing attacks that can mislead devices about the distance between them, potentially leading to unauthorized access by altering time-of-flight measurements.

Innovation Solution

Incorporating a sequence of symbols in wireless packets with a non-repeating pattern and correlator operations using overlapping three-symbol-length correlation windows to distinguish between direct and reflected signals, correcting time stamp information to accurately determine range, and ignoring late arrival peaks indicative of spoofed signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional wireless communication protocols are used for distance measurement, then devices can exchange timestamped messages to determine range, but the system becomes vulnerable to spoofing attacks that can mislead distance measurements

Engineering Contradiction:

Improverange measurement accuracyVSAvoidsecurity against spoofing attacks

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent applies the principle of 'Color changes' by using distinct symbol patterns as a form of digital signature or identification. Each legitimate device uses a specific, predetermined symbol pattern that acts like a unique identifier. The receiving device can verify the authenticity of incoming messages by checking whether the symbol pattern matches the expected pattern, thereby detecting and rejecting spoofed messages that use incorrect or unauthorized patterns.

Inventive Principle:

Principle #32Color changes

Solution Approach 2:

The patent applies the principle of 'Intermediary (Mediator)' by introducing a sequence of symbols as an intermediary element between the timestamp data and the range measurement process. This symbol sequence acts as a mediator that verifies the authenticity of the message before the timestamp is processed for distance calculation. The correlator serves as another intermediary that compares received symbols against expected patterns, adding a layer of verification that prevents spoofing attacks from successfully manipulating range measurements.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If devices use timestamped message exchange for ranging, then distance can be determined, but spoofed signals can create false time stamps that lead to unauthorized access

Engineering Contradiction:

Improverange determination capabilityVSAvoidspoofing attacks enabling unauthorized access

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent applies the principle of 'Preliminary action' by pre-establishing and distributing known symbol patterns to legitimate devices before the ranging process begins. These predetermined symbol sequences are stored in advance in each device's memory. When a message is received, the correlator can immediately compare the incoming symbol sequence against the pre-stored patterns without requiring complex real-time analysis, enabling quick verification of authenticity before processing the timestamp for range determination.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies the principle of 'Intermediary (Mediator)' by introducing a sequence of symbols as an intermediary element between the timestamp data and the range measurement process. This symbol sequence acts as a mediator that verifies the authenticity of the message before the timestamp is processed for distance calculation. The correlator serves as another intermediary that compares received symbols against expected patterns, adding a layer of verification that prevents spoofing attacks from successfully manipulating range measurements.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If a simple packet format is used for wireless communication, then transmission is efficient, but the packet lacks protection against spoofing attacks

Engineering Contradiction:

Improvecommunication efficiencyVSAvoidresistance to spoofing attacks

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies the principle of 'Merging (Combining)' by integrating the symbol sequence directly into the existing packet structure between the start-of-frame delimiter and the physical layer header. Rather than adding a separate verification channel or using a completely different communication protocol, the authentication symbols are merged into the data payload area of the standard packet format. This allows the packet to carry both the traditional data information and the authentication symbol sequence in a unified structure, maintaining communication efficiency while adding spoofing protection.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS10158997B2Wireless system with secure range determination

Publication Date: 2018.12.18 APPLE INC

AI summary

A wireless network may include devices that wirelessly transmit and receive packets. Each packet may include a preamble, a start-of-frame delimiter, a physical layer header, a sequence of symbols between the start-of-frame delimiter and the physical layer header, and a data payload. The sequence of symbols may have a pattern that is resistant to spoofing attacks. A receiving device may have a correlator that correlates known symbols against the symbols in the sequence using overlapping three-symbol-length correlation windows. Early arrival peaks in the output of the correlator may be used to correct time stamp information in the packets and late arrival peaks corresponding to spoofed signals from an attacker may be ignored. Time stamp information may be processed to determine ranges between transmitting and receiving devices.