Nearables ranging in iOS

Currently we have a requirement like, needs to get the list of nearables with a state of Immediate/Near to the iPhone/iOS app with in a specific time i.e. 5 sec. For that we are using nearales ranging. We have around 30 strikers are there with in 5-10 sec we are getting only 4-7 stickers listing with the above criteria.
So we want to know what was the maximum stickers that will list with in 5-10 sec with out any obstacles in between the iPhone and sticker ?