Physical Distance Enforcement for Data Distribution
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Solution Overview
Problem
Existing methods for restricting content distribution to a narrow physical domain, such as a single dwelling, are ineffective due to the use of virtual private networks (VPNs) that can hide intermediate nodes, making it difficult to enforce geographical limitations.
Innovation Solution
A method and apparatus that estimate the distance between entities and authorize data transmission only if within a threshold distance, using techniques like clock synchronization and propagation delay measurement, ensuring physical locality and preventing VPN bypasses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If IP hop counting is used to limit content distribution to a single location, then geographical limitations can be enforced, but VPN connections can bypass this restriction by hiding intermediate nodes
Solution Approach 1:
The patent replaces the logical/IP-based hop counting mechanism with a physical measurement mechanism using time-of-flight (ToF) calculations. By measuring the actual propagation time of data packets and converting it to physical distance using the speed of light, the system enforces geographical limitations based on physical reality rather than network topology, which cannot be manipulated by VPN connections.
Solution Approach 2:
The patent changes the parameter used for geographical limitation enforcement from logical network hops to physical distance measurements. By calculating actual physical distance through ToF measurements and comparing against a distance threshold, the system creates an unbreakable geographical barrier that VPN connections cannot circumvent, as the physical distance remains constant regardless of network routing.
2Reliability
If physical distance measurement is implemented to enforce geographical limitations, then VPN bypass is prevented, but system complexity increases due to clock synchronization and time measurement requirements
Solution Approach 1:
The patent introduces a mediator component (distance calculation module) that handles the complex clock synchronization and time-of-flight calculations. This mediator receives timestamps from source and destination devices, performs the necessary calculations to determine physical distance, and makes the authorization decision, thereby isolating the complexity from the endpoint devices.
Solution Approach 2:
The patent performs clock synchronization as a preliminary action before actual content transmission. By pre-synchronizing clocks between source and destination devices using protocols like NTP or PTP, the system ensures that time measurements are accurate without adding complexity during the actual content delivery process.
3Measurement precision
If time-of-flight measurement is used to determine physical distance, then accurate geographical enforcement is achieved, but measurement precision requirements increase due to the need for accurate clock synchronization
Solution Approach 1:
The patent uses excessive clock synchronization precision beyond what is strictly necessary for the application. By implementing clock synchronization with precision far exceeding the minimum requirement (e.g., using hardware timestamps with nanosecond or picosecond resolution), the system ensures that measurement precision is not limited by timing inaccuracies, even though this requires more time and resources for synchronization.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively enforces geographical limitations by accurately determining the distance between entities, preventing unauthorized data distribution beyond a defined physical domain, even with VPN usage.
Implementation Method 1
estimating a physical distance between the source device and the sink device... measuring the time for the data packet to travel from the source device to the sink device
Implementation Method 2
synchronizing clocks of the source device and the sink device... clock synchronization and propagation delay measurement
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A method and system for ensuring that data is only distributed within a certain physical area are disclosed. In one embodiment, a method provides that data is distributed only if the distance between a source and a sink is within a distance threshold. Under this system, the distance between the source and the sink may be estimated directly or indirectly. In some embodiments, the distance may be estimated by estimating the propagation delay for a signal traversing between the devices. The physical distance between the devices may be determined from the propagation delay. If the physical distance is outside a threshold value, the source may be prohibited from transmitting the data or the sink may refuse to display the data.