To clarify the scope of the initial MLS use in FxOS: We are first looking at Tarako devices, which don’t have a GPS chip. So in order to provide user-value, all we have to do is beat “no position estimate”.
One primary way to achieve this is using GeoIP, which will give you country or city-level position estimates. That’s not great for many use-cases, but it’s better than nothing. One example might be an app showing you restaurants around you. The alternatives are either to show a default world-wide view (with no position estimate) or to zoom the map view to the country / city you are actually in. The latter still requires the user to pan and zoom a bit to get to the right area, but it’s better than a world-wide view. While GeoIP is pretty bad for mobile networks, a lot of the target users will use WiFi networks to access the internet, as the data connections are too unreliable/slow/expensive. GeoIP works better for those landline-based WiFi networks. In addition the code is already in FxOS to send observed cell and wifi networks along to MLS. So once we get more and better data for the countries in question, the user experience will get better without any need to update the client software. A second use-case on more capable hardware is around misconfigured or missing A-GPS support in FxOS devices. One part of A-GPS is to inject a coarse position estimate into the GPS chip with an accuracy required to be in the order of 100-200km. This helps the GPS chip to figure out which satellites should be visible in the sky and look for their specific signals. As this use-case only requires a very coarse grained position estimate, it’s also something we can provide based on the current MLS. This helps with reducing the “time to first fix” from a worst case of 12 minutes to much less time. Of course we want to provide better position estimates and make the service useful for other use-cases. But that requires a mixture of getting much more data and better algorithms and approaches on collecting and processing that data. Those things are underway, but don’t have to block MLS use in FxOS, as we can already provide some user value. On 25.03.2014, at 06:05 , Adrian Custer <[email protected]> wrote: > It would be interesting to have the discussion of the work you are doing to > bring the whole system up to production quality on the > https://mozilla-ichnaea.readthedocs.org/en/latest/calculation.html > web page. That should probably include a discussion of all the different > error terms you are considering in the position analysis and how multiple > observations attenuate the different terms. The short answer is: We aren’t doing any real work in the current codebase. The assumption so far is that we only get a single or very few observations for any given cell or wifi network, as most of the areas are only stumbled once or very infrequently for each cell network / cell standard combination. With so little data per network, there’s not a whole lot of algorithms you can use. We are fully aware that this leads to position estimates with low accuracies. To cover the widest area we are going to rely on cell networks. As a result of limitations in GSM networks, the devices will only send us a single cell observation for the currently connected cell. The best we can do here is to equate the estimated user position with the center of the cell and a range estimate of the cell size (this method is generally known as CellId). That leads to accuracies in the kilometer range for urban areas or tens of kilometers in suburban/rural areas. The GPS inaccuracies or inaccuracies from sensor / timing mismatch aren’t having a big impact at this scale. I’m more than interested in hearing about your work and your own conclusions. We will look at better algorithms in the near future. But those are a secondary priority after getting any data at all. We are following a very incremental approach here, where we try to provide value at each step of the process and not wait until we can beat the current market offerings from competitors with many years of experience. Hope this clarifies the current situation a bit. Hanno _______________________________________________ dev-geolocation mailing list [email protected] https://lists.mozilla.org/listinfo/dev-geolocation
