A range of solutions are vying to replicate what GPS does outdoors in an indoor environment, from Wi-Fi to Bluetooth to “terrestrial” GPS, plus many others. Which one is likely to be successful? IMS Research (recently acquired by IHS Inc.) said the answer will not simply be just “one.” Locating a smartphone in an outdoors environment is straightforward, with more than 90 percent of smartphones providing GPS functionality. However, GPS becomes less useful in built-up areas and can be useless indoors, reports IMS Research.