Indoor Positioning System Explained: BLE, UWB, and Wi-Fi Accuracy Compared

Why GPS Fails Indoors — and What Replaces It

GPS relies on a clear line of sight to satellites, so signal strength drops sharply behind concrete, steel, and low-E glass — the exact materials most buildings are made of. An Indoor Positioning System (IPS) solves this by using short-range radio technologies already present inside a building — Bluetooth Low Energy (BLE), Ultra-Wideband (UWB), Wi-Fi, or RFID — to estimate where a tagged person or asset is, room by room or even centimetre by centimetre.

Accuracy vs. Precision: Two Different Questions

These terms get used interchangeably, but they answer different questions. Accuracy is how close a position reading is to the true location. Precision is how consistent repeated readings are with each other, even if they are consistently off-target. A system can be precise but inaccurate (tight cluster of readings, all 2 metres off) or accurate but imprecise (readings centred on the right spot but scattered widely). A serious IPS deployment needs both: consistent, repeatable readings that are also close to ground truth — which is why vendors should quote accuracy as a distribution (e.g. the 90th percentile), not a single best-case number from a clean lab environment.

How the Technologies Actually Compare

Real-world accuracy depends heavily on the environment — metal racking, forklifts, and dense Wi-Fi interference all degrade performance versus a lab test. Typical ranges seen in production deployments:

• UWB (time-of-flight ranging): 10–30 cm accuracy. The gold standard for precision, but requires dedicated anchor infrastructure and a higher upfront cost.
• BLE with Angle of Arrival (AoA): roughly 0.5–1 m accuracy using multi-antenna locators — a strong middle ground between UWB precision and BLE's low cost.
• Wi-Fi RTT / fingerprinting: 3–10 m accuracy, but reuses access points you likely already have installed.
• BLE RSSI (signal-strength trilateration): 5–10 m accuracy in typical conditions — walls, metal shelving, and body attenuation all distort the raw signal.
• RFID: not a continuous positioning technology at all — it confirms an asset passed a specific checkpoint or gate, which is often all that is actually needed.

Choosing the Right Technology for Your Use Case

The most expensive, most accurate option is rarely the right default. A warehouse that only needs to confirm pallets left the loading dock doesn't need sub-metre UWB — RFID checkpoints or BLE RSSI zones are cheaper and simpler to maintain. A hospital that needs to find a specific infusion pump on a specific floor within seconds needs room-level accuracy, which BLE AoA delivers at a fraction of UWB's infrastructure cost. Reserve UWB for scenarios where centimetre precision genuinely changes the outcome — automated guided vehicles, precision manufacturing lines, or safety-critical proximity zones.

Test Before You Commit

Vendor spec sheets are measured in ideal conditions. Before standardising on a technology, run a paid pilot in your actual space — the same racking, the same forklifts, the same RF noise you'll operate in day to day. Cubeacon runs a free site survey for exactly this reason: a floor plan and a stack of shelving can change which technology makes sense more than any brochure will.