Your concerns about bad data from dodgy hardware seem real, but it seems like their system is meant to be used while in motion. From the article: "We therefore

Your concerns about bad data from dodgy hardware seem real, but it seems like their system is meant to be used while in motion. From the article: "We therefore use past measurements and constrain the location evolution over time using a motion model adapted to the application (e.g., pedestrian vs. vehicular motion)." … "Over time, the probability weights and particle locations evolve based on the measurements and the motion model." Presumably this means something along the lines of throwing out hypothesized locations based on impossible movements. If they were very sure that a car was at a particular location 5 seconds ago and now it is at another location 100 meters away, then that's believable because cars can travel at that speed (~40 mph or ~65 km/h). But if dealing with a pedestrian, it indicates low probability of the latest measurement being correct. I'm just guessing on the specifics of what the motion model does. But it seems like they're trying to use history in more cases than just when someone is sitting still.