The History of Positioning ② — Where GPS Stops: The Battle of Indoor Positioning Technologies

In the previous installment, we traced the history of positioning from whale song to sonar, radar, radio navigation, and finally GPS. That story ended with a paradox: GPS, which can tell you where you are anywhere on Earth, falls silent precisely where we spend most of our day — indoors. This is why indoor positioning was born as a separate field of technology.

This installment begins with that paradox. Where GPS stops — inside buildings — indoor positioning technologies have long fought a fierce contest to locate people and assets. WiFi, BLE beacons, UWB, vision AI, inertial sensors — challengers each armed with a different principle and a different weapon.

Let it be said up front: this contest has no single winner. And that very fact has shaped the direction of today's indoor location industry. How does each technology fight, why has no champion emerged, and what, then, is the practical answer? Let's take them in turn.

I. Where the Last Signal Dies — Why Indoor Positioning Is Hard

GPS signals arrive from satellites in distant orbit. By the time they complete that long journey to the ground, they are already extremely faint — and concrete walls and steel structures let almost none of that fragile signal through. That is why the connection to the sky is severed the moment you step inside a building.

The problem is not only that the signal cannot get in. To radio waves, an indoor space is a kind of hall of mirrors. Walls and ceilings, metal shelving and equipment — every surface indoors reflects radio waves. A single signal bounces along multiple paths and reaches the receiver several times, a phenomenon called multipath. From the receiver's point of view, it is hard to tell which arrival is the true line-of-sight signal, and distance calculations blur accordingly.

In the end, indoor positioning was never a matter of "extending" GPS indoors — it was a separate problem requiring entirely different tools. And here, five lines of challenge begin.

II. Five Challengers — The Candidate Technologies of Indoor Tracking

1. WiFi — The Power of Infrastructure Already in Place

WiFi positioning starts from a simple premise. Buildings are already full of WiFi access points (APs), and the signal strength (RSSI) a device receives generally weakens with distance from the AP. That signal strength serves as a clue for estimating distance — or, going one step further, a technique called fingerprinting maps the signal patterns across a building in advance and matches current measurements against that map.

Its greatest appeal is that existing infrastructure can be reused. You can start without any new hardware. But signal strength is a jittery metric, swayed by a human body, a passing forklift, even a single closed door. WiFi positioning accuracy therefore typically stays at the meter level. It is enough for "which floor, which zone" — but little beyond that.

2. BLE Beacons — Low-Cost, Low-Power Pragmatism

A BLE (Bluetooth Low Energy) beacon is a small transmitter the size of a coin. It runs a long time on a single battery and costs little, so it can be installed throughout a building without much burden. The principle is signal-strength-based like WiFi, so accuracy is likewise at the meter level — but BLE's real stage lies elsewhere. Proximity detection and zone-level awareness: for problems like "this asset has entered warehouse zone 3" or "a visitor is standing in front of this exhibit," BLE is the most practical answer for the cost.

3. UWB — Measuring Distance with a Nanosecond Clock

UWB (ultra-wideband) takes a fundamentally different approach. It measures not how strongly a signal arrives, but how fast. It fires extremely short pulses on the order of nanoseconds and measures the Time of Flight (ToF) — how long the radio wave took to travel — then converts that into distance. The speed of radio waves never changes, so if time can be measured precisely, distance becomes precise too.

Sharp pulses are also resilient to multipath, because reflected, late-arriving signals can be separated from the direct signal along the time axis. As a result, UWB achieves accuracy in the tens of centimeters indoors. Of course, it is not free: an infrastructure of anchors — fixed positioning reference points — must be installed throughout the space. This is why UWB is the choice in factories, logistics centers, and heavy-equipment sites, where accuracy translates directly into safety and cost.

4. Vision AI — Eyes That See Without Tags

The three technologies above all require the tracked target to carry a tag or device. Vision (camera AI) flips that premise. AI analyzes camera footage to recognize people and objects, so it can capture even outside visitors and vehicles that cannot be handed a tag. In exchange, anywhere a camera cannot see might as well not exist. The physical limits of blind spots and lighting come attached, and when the view is blocked, tracking breaks off with it.

5. Inertial Sensors and Geomagnetics — The Quiet Supporting Cast

An IMU (inertial measurement unit) senses acceleration and rotation to compute "which direction, and how far, did I just move," while geomagnetic methods use each building's subtly distinct magnetic field patterns as a map. Operating without any external signal is their appeal, but inertial approaches cannot escape drift — small errors that accumulate over time. So these technologies shine not as protagonists but as supporting players that fill the gaps other technologies leave behind.

III. Side by Side — Indoor Positioning Technologies at a Glance

Technology	Principle	Accuracy (approx.)	Strengths	Weaknesses
WiFi	Signal strength (RSSI), fingerprinting	Meter-level	Reuses existing infrastructure	Swayed by interference and environmental change
BLE beacons	Signal-strength-based proximity detection	Meter-level	Low cost, low power; ideal for zones	Insufficient for precise coordinates
UWB	Time of Flight (ToF) of nanosecond pulses	Tens of centimeters	High precision, resilient to multipath	Requires anchor infrastructure
Vision AI	AI analysis of camera footage	Varies by installation environment	No tags needed; detects outsiders and vehicles	Blind spots and lighting limits
IMU / geomagnetic	Inertia and magnetic field patterns	Supplementary	No external signal needed	Cumulative error (drift)

As the table makes clear, no technology wins in every column. UWB, the king of accuracy, needs infrastructure; WiFi, which needs no infrastructure, gives up accuracy; vision, which needs no tags, is bound to its field of view. Beside every strength, a weakness stands like a shadow.

IV. The Answer to a Contest Without a Winner: Combination

So what do real sites choose? The answer is not choosing — it is combining.

It makes sense when you think about it. Even within a single building, requirements differ from place to place. One area may need to watch the distance between workers and heavy equipment within tens of centimeters for safety, while another only needs to know which warehouse zone an asset is in. Entry by outside vehicles that cannot be tagged has to be handled by cameras. Depending on how the three variables — accuracy, cost, and tracking target — combine, the optimal technology differs zone by zone.

The trouble comes next. The moment you mix technologies, you mix screens too. If UWB keeps its own system and screen, BLE its own, and cameras their own, the person doing the monitoring gets lost in a forest of monitors. That is why the decisive battleground of indoor tracking is shifting beyond individual technology performance to platform capability — the ability to bring data from multiple technologies together onto a single map.

This is exactly where ORBRO stands. ORBRO delivers both precision positioning and zone-based tracking through ORBRO RTLS, which spans UWB and BLE, and detects untagged people and vehicles with its vision AI product, AI Event Manager. All of that data then meets on a single screen in the monitoring platform ORBRO OS. However the technology mix differs from site to site, the person watching sees one unified site — that is ORBRO's answer to a technology contest without a winner.

Closing

The indoor positioning contest that began where GPS stops arrived not at a single champion but at an answer: combination and integration. Yet even within that combination, one technology clearly serves as the reference point for precision — UWB, which resolves tens of centimeters with nanosecond pulses.

In the next installment, we open up UWB itself. How do you measure invisible nanoseconds of time, and how does that sliver of time become centimeter-level coordinates? The story continues in Part 3 of the History of Positioning: "The Science of the Nanosecond — How UWB Measures Centimeters."