Get Location without wi-fi connection

I'm using Xam.Plugin.GeolocatorPlugin in xamarin forms portable project, and i'm trying to get the GPS location , the code works when wi-fi is turned on. But when wi-fi of device is turned off, never works.
Someone know why?

var locator = CrossGeolocator.Current;
locator.DesiredAccuracy = 50;
var position = await locator.GetPositionAsync(timeoutMilliseconds: 30000);