Bluetooth Device Geo-location via Packet Time Delay
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Solution Overview
Problem
Existing methods for geo-locating Bluetooth devices require user interaction and established connections, which is not feasible for unattended or passive location tracking, especially for Un-Discoverable Classic Bluetooth Basic Rate devices.
Innovation Solution
A method involving a wireless receiver that initiates a paging sequence with a second wireless transmitter/receiver, records packet reception times, and calculates a time delay to determine the location of the second device without establishing an explicit ACL connection, using a Link Management Protocol (LMP) name request and packet types like POLL and NULL to facilitate location determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If user interaction and established connections are required for geo-location, then location accuracy can be determined, but the system cannot track unattended or passive devices
Solution Approach 1:
The target Bluetooth device automatically responds to paging messages and exchanges packets without requiring user interaction. The device self-manages the connection establishment and location determination process by automatically responding to POLL packets and sending NULL packets, enabling unattended tracking.
Solution Approach 2:
The system performs preliminary packet exchange and connection establishment actions before actual location determination is needed. By pre-establishing the communication channel through automated paging and packet exchange, the system prepares the groundwork for subsequent location measurements without requiring user intervention at the time of tracking.
2Reliability
If an explicit ACL connection is established for location determination, then reliable packet exchange can occur, but the tracking process becomes more complex and intrusive
Solution Approach 1:
The system performs a partial connection establishment through packet exchange without completing the full ACL connection process. By exchanging only the necessary POLL and NULL packets required for timing measurement, the system achieves sufficient reliability for location determination while avoiding the complexity and intrusiveness of a complete connection setup.
3Measurement precision
If packet exchange is used to calculate time delay for location determination, then accurate geo-location can be achieved, but the process requires precise timing measurement which complicates the system
Solution Approach 1:
The Bluetooth devices themselves generate and respond to the timing signals through their standard packet exchange protocol. The POLL and NULL packets are transmitted at predetermined intervals defined by the Bluetooth specification, allowing the system to utilize the devices' inherent timing mechanisms rather than requiring external timing infrastructure, thus reducing overall system complexity while maintaining precision.
Data Source
AI summary
A method, device and system are disclosed for geo-locating a device. In one embodiment, a first wireless transmitter/receiver pages a second wireless transmitter/receiver to establish a communication. A plurality of packets transmitted by the first wireless transmitter/receiver and transmitted by the second wireless transmitter/receiver are received by a wireless receiver. The reception time of packets transmitted by the first wireless transmitter/receiver and the second wireless transmitter/receiver is recorded. A time delay based at least in part on the recorded reception times of each packet is calculated, and a location of the second wireless device based on the calculated time delay is determined. A target location of the second wireless transmitter/receiver is determined based on a plurality of the determined locations of the second wireless transmitter/receiver.