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The problem
GPS stops at the front door: satellite signals are far too weak to penetrate buildings reliably, yet the interesting tracking problems — where is the lab equipment, which room is the patient monitor in, how do visitors move through a museum — all happen indoors. Bluetooth Low Energy beacons are the standard low-cost answer: tiny battery-powered transmitters that broadcast an identifier several times a second, letting any receiver estimate distance from signal strength. This project builds a complete indoor positioning system around the ESP32, which has BLE and Wi-Fi on one chip. Three or more ESP32 beacons are fixed at known positions in the room; an ESP32 gateway scans their advertisements plus the tag's, converts RSSI to distance estimates with a calibrated path-loss model, and publishes the results over MQTT. A web dashboard renders the live position on a floor plan with per-beacon signal bars. The honest engineering lesson is multipath: walls, furniture and human bodies scatter 2.4 GHz signals, so RSSI positioning gives room/zone-level accuracy (design target roughly 2–5 m), not GPS-style precision — and the report measures and documents exactly that.
BLE tag carried by the asset; its advertisements are scanned for RSSI like the beacons'.
Follow the working sequence
How it works
- Each ESP32 beacon broadcasts BLE advertisements containing its ID at a fixed interval (e.g. 500 ms) from a known, configured position in the room.
- The ESP32 gateway scans continuously, recording the RSSI of every advertisement it hears from the beacons and from the tracked tag.
- RSSI values pass through a moving-average filter to smooth fast fading, then the calibrated path-loss model converts each to a distance estimate.
- Trilateration combines the distance estimates from three or more beacons into a 2D coordinate; with fewer beacons the system falls back to nearest-beacon zone.
- The gateway publishes the position fix and raw RSSI over MQTT/Wi-Fi to the dashboard backend.
- The web dashboard plots the tag on the floor plan, updates per-beacon signal bars, and logs the track history for the demo.
Tech stack:
- ESP32 (beacon firmware, gateway scanner) with Arduino framework
- BLE advertisements (iBeacon/Eddystone-style format)
- MQTT over Wi-Fi for telemetry
- Log-distance path-loss model with per-beacon calibration
- Trilateration in the gateway firmware
- Web dashboard (HTML/JS with SVG floor plan, MQTT over WebSockets)
| Parameter | Value |
|---|---|
| Beacons | ESP32 boards, battery-powered, BLE advertisements at configurable interval |
| Gateway | ESP32 scanner + Wi-Fi MQTT publisher |
| Positioning method | RSSI trilateration (log-distance path-loss model, per-beacon calibration) |
| Accuracy | Room/zone-level; design target roughly 2–5 m in a furnished room (environment-dependent) |
| Update rate | Position fix per scan cycle (configurable, typically ~1–2 s) |
| Connectivity | BLE for ranging, Wi-Fi/MQTT for telemetry, WebSocket dashboard |
| Power | Beacons run on batteries (life depends on advertising interval); gateway USB-powered |
| Dashboard | Live floor map, RSSI diagnostics, zone display, track history |
Project features
- [ESP32 BLE beacon firmware] Battery-friendly firmware broadcasting iBeacon/Eddystone-style advertisements with configurable TX power and advertising interval.
- [RSSI-to-distance engine] A calibrated log-distance path-loss model converts RSSI to distance estimates, with per-beacon calibration constants stored in config.
- [Trilateration positioning] The gateway combines distance estimates from three or more beacons into a 2D position fix, recomputed on every scan cycle.
- [MQTT telemetry pipeline] Position fixes and raw RSSI readings publish over MQTT/Wi-Fi, decoupling the embedded side from the dashboard.
- [Live floor-map dashboard] A web dashboard draws beacons, the estimated tag position and a movement trail on a floor plan, updating in real time.
- [Zone detection] Named zones (e.g. "Lab A", "Corridor") resolve from the nearest beacon or position fix, so the system answers "which room" even when the exact coordinates wobble.
- [Signal diagnostics view] Per-beacon RSSI bars, packet counts and last-seen timestamps make multipath and dead zones visible instead of mysterious.
- [Configurable beacon layout] Beacon coordinates and zone polygons are config-file driven, so the system adapts to any room without firmware changes.
What is included
- Beacon firmware source code (advertising, TX power and interval configuration)
- Gateway firmware source code (scanning, filtering, trilateration, MQTT publishing)
- Web dashboard (floor-map view, diagnostics, zone display)
- Calibration procedure (measuring path-loss constants in your room, buyer-run)
- Circuit notes and beacon placement guide
- Project report PDF (BLE theory, RSSI ranging, trilateration math, measured accuracy)
- PPT presentation for final review
- Viva Q&A preparation document (BLE advertising, RSSI vs ToF, multipath, trilateration)
Advantages
- Battery-friendly ESP32 beacon firmware broadcasts iBeacon/Eddystone-style advertisements with configurable TX power and advertising interval.
- A calibrated log-distance path-loss model converts RSSI to distance estimates, with per-beacon calibration constants stored in config.
- The gateway combines distance estimates from three or more beacons into a 2D position fix by trilateration, recomputed on every scan cycle.
- Position fixes and raw RSSI readings publish over MQTT/Wi-Fi, decoupling the embedded side from the dashboard.
- The live floor-map dashboard draws beacons, the estimated tag position and a movement trail on a floor plan, updating in real time.
- Named zones such as Lab A and Corridor resolve from the nearest beacon or position fix, so the system answers which room even when exact coordinates wobble, and a signal diagnostics view shows per-beacon RSSI bars, packet counts and last-seen timestamps.
Disadvantages
- RSSI positioning is inherently room/zone-level: multipath reflections, furniture and human bodies make 2.4 GHz signal strength noisy, so the design target is roughly 2-5 m and centimetre or sub-metre claims would be dishonest.
- Accuracy must be calibrated per room, since the path-loss constants depend on the environment, and moving the system to a new room without recalibration degrades results.
- At least three beacons with good geometry are needed for trilateration; with fewer, or beacons in a straight line, the system degrades to nearest-beacon zone detection.
- Beacon battery life trades directly against advertising interval and TX power: faster updates mean shorter battery life.
- The 2.4 GHz band is shared with Wi-Fi, so heavy nearby Wi-Fi traffic can add noise to RSSI readings, and this is a prototype demo, not a safety-critical tracking system.
Limitations & prerequisites
- RSSI positioning is inherently room/zone-level: multipath reflections, furniture and human bodies make 2.4 GHz signal strength noisy, so centimetre or sub-metre claims would be dishonest — the design target is roughly 2–5 m and the report measures your room's actual error.
- Accuracy must be calibrated per room: the path-loss constants depend on the environment, and moving the system to a new room without recalibration degrades results.
- At least three beacons with good geometry are needed for trilateration; with fewer, or beacons in a straight line, the system degrades to nearest-beacon zone detection.
- Beacon battery life trades directly against advertising interval and TX power: faster updates mean shorter battery life, documented in the power notes.
- The 2.4 GHz band is shared with Wi-Fi; heavy nearby Wi-Fi traffic can add noise to RSSI readings.
- This is a prototype positioning demo, not a safety-critical tracking system; it is not suitable for applications where a wrong position has real consequences.
Frequently Asked Questions
Which controller is used?
ESP32 for everything: the beacons (BLE advertising) and the gateway (BLE scanning plus Wi-Fi/MQTT). One chip covers both radios, which keeps the hardware bill small.
How accurate is it really?
Room/zone-level. Expect roughly 2–5 m in a furnished room after calibration — good enough to say which room or area a tag is in. Multipath makes true precision positioning a research problem, not a student-project outcome, and the report is honest about the measured error.
Does it work without Wi-Fi?
The BLE ranging side needs no Wi-Fi, but the live dashboard needs the gateway's MQTT link, which runs over Wi-Fi. Without Wi-Fi you can still log positions to the gateway's serial output.
Can I track multiple tags?
Yes. Each tag advertises a unique ID and the gateway computes a fix per ID; the dashboard renders multiple tracks. More tags mean more scan-cycle load, which the firmware notes cover.
What is actually implemented vs optional?
Implemented: beacon firmware, gateway with trilateration, MQTT pipeline, floor-map dashboard, zone detection, diagnostics. Optional on request: fingerprinting-based positioning, phone-app receiver, cloud logging.
Can the beacons be replaced with off-the-shelf BLE tags?
Yes — any BLE advertiser with a known ID works as a beacon or tag, though TX-power calibration should be redone for the new hardware. Suitable for B.E./B.Tech final-year projects in Electronics, IoT and Embedded Systems.
Components & software requirements
- ESP32 (beacon firmware, gateway scanner) with Arduino framework
- BLE advertisements (iBeacon/Eddystone-style format)
- MQTT over Wi-Fi for telemetry
- Log-distance path-loss model with per-beacon calibration
- Trilateration in the gateway firmware
- Web dashboard (HTML/JS with SVG floor plan, MQTT over WebSockets)
Delivery information
Built-to-order project. Delivery timeline is shared after order confirmation based on current queue.
Support terms
Complete documentation, setup guide, and viva preparation included. Support for setup and explanation provided.
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