Indoor detection

Knowing when GNSS is useless - and acting on it

GNSS is one of the most versatile positioning technologies available. It’s accurate, global, and infrastructure-free. But it doesn't work indoors. As consumer demand for battery life and reliability of position accuracy have grown, the focus on how GNSS-enabled devices function indoors has sharpened. 

Detecting when a device is indoors reliably enables you to build more power-efficient devices that also deliver greater certainty around position to users.
 

 

What happens when GNSS goes indoors

Power consumption rises  

When a GNSS receiver moves indoors, it keeps trying to get a position fix by searching satellite signals. Searching satellites to achieve a position fix is more power-intensive than maintaining a fix, decreasing battery life.

Position accuracy degrades

The satellite signals that do reach a receiver indoors are predominantly reflected off walls, ceilings, surrounding structures and heavily attenuated. The positions calculated from these signals are unreliable - sometimes significantly offset from the device's actual location. Depending on the application, reporting these positions can be worse than reporting nothing at all.

When to deploy alternative localisation?

Some tracking devices are built with additional sensors designed to provide location data when GNSS signal is blocked. But without a mechanism for the MCU to detect that it is indoors, the system may not always prioritize data from additional sensors when reporting position and movement.

How u-blox indoor detection works  

Indoor detection is a proprietary u-blox algorithm that determines whether a GNSS receiver has moved into an indoor environment. It is triggered within a few seconds when GNSS quality falls below predefined thresholds, typically because too few satellite signals are available. Signals that are too weak are excluded from the assessment. Because the algorithm relies solely on satellite data already being processed by the receiver, it requires no additional sensors, no extra hardware, no added BOM cost.

The algorithm continuously analyses the quality of received satellite signals and reports its assessment as part of the UBX-NAV-STATUS message sent by the u-blox hardware. This gives the host MCU a real-time, reliable signal it can act on, whether that means switching the GNSS receiver off when indoors, initiating a handoff to an alternative location technology such as Wi-Fi, or both.

Implementation is straightforward, and the absence of additional hardware requirements keeps integration complexity low. 

Indoor detection use cases 

Asset tracking 

Asset trackers typically wake up periodically to report position, then return to sleep. If a device wakes while indoors, it will spend its GNSS on-time searching for signals it can't properly receive, draining battery without producing useful positioning data. Indoor detection allows the host MCU to recognize this situation and skip the GNSS cycle entirely, preserving battery for the moments when a position fix is actually achievable.

Vehicle tracking

Entering a tunnel can product significant position offsets as reflected signals distort the receiver's location estimate. For fleet management or logistics applications, these corrupted positions can introduce errors into route data or trigger false alerts. Indoor detection allows the MCU to ignore GNSS output while the vehicle is in the tunnel, ensuring only reliable positions reach the application.

Pet and people tracking

Indoor detection integrates naturally with other location technologies. Combined with Wi-Fi home zone detection, it improves the overall quality of indoor/outdoor classification - allowing GNSS to be switched off sooner and more reliably when a pet or person is inside. The result is lower average power consumption without any reduction in tracking capability when it matters.