Is wifi/bluetooth Triangulation(not trilateration) using a mobile device possible?

Question

Well for triangulation you need to have the direction from which your device is receiving the signal.We can calculate Angle of Arrival for that but calculating that angle requires an array of receivers. Is a cell phone capable of calculating Angle of Arrival? I am asking this because I have came across the terms like wifi/BLE triangulation, calculating position by triangulation etc but they're actually referring to Trilateration in most of the cases. I know how trilateration works for a mobile and all the details but I don't think Triangulation is possible. And if it is possible, how is it possible and which one (triangulation or trilateration) is expected to give better result if you use ibeacons to approximate positions?

Rugged

Answer 1

Lot of people are misleading terms as you pointed out. Triangulation is not possible with standard ble beacons or WiFi (I mean without modify the standard ble 4.0 or 4.1 and WiFi) right now because the standard doesn't report useful information like the phase (if you have phase and an array of directional antennas that are powered on one per time at a predetermined frequency you can use algorithms like MUSIC and deal with angles) but we only have Rssi and TX power at one meter(if it's an iBeacon) with those information we can estimate the distance that is very imprecise and fluctuate rapidly over time because of multipath and diffraction. In Nextome we have invented an algorithm to mitigate multipath fading that causes signal to bounce and achieve high accuracy Indoor Positioning of about 1 meter without fingerprinting. No one has tested triangulation with standard iBeacons right now but trilateration. I would start looking at least square approximation to solve the trilateration problems, but don't expect big results without filtering out the noise.

Weatherboarding

Thank you that's what I wanted to know. And this algorithm to mitigate multipath fading, is it private or I can have a look at it somewhere sir? 1 meter accuracy is very impressive. – Rugged

Dear friend and researcher the algorithm is private because it's in patent pending form right now. I think that soon will be publicly available when the patent will be filed. Thanks – Weatherboarding

Is the algorithm available now?? – Overlord

Answer 2

Mobile mast triangulation usually uses the power level to estimate how far a phone is from a particular cell tower. At any given time a phone will generally be in touch with several towers, even though it is only using one at a time for calls etc.

If you have an estimate of the distance from two or more towers you can imagine drawing a circle around each tower with the radius equal to this distance.

Where the circles intersect is the 'likely' position(s) of the mobile device.

WiFi estimation works on roughly the same principles but is much more accurate as there are so many more WiFi networks.

The big data aggregators (Goggle, Apple etc and their partners) receive data from millions of phones which allows them accurately locate where a particular WiFi network is located. When you then ask your phone to check you position they are able to see what WiFi networks you are close to and vey accurately narrow down your position, especially in a built up area with many WiFi networks.

Most phone positioning systems will use a mix of technologies, GPS, cell strangulation, WiFi to help narrow down your location.

Of course if you are on top of a mountain or in desert the options are a bit more limited, and GPS becomes more important...

Observation

Again what you said is Trilateration, I was enquiring about Triangulation which is little different : en.wikipedia.org/wiki/Triangulation I was aking if getting angles and then pinpointing the position (Triangulation) possible for a cell rather than getting distances and then finding out the position (Trilateration). – Rugged

I think you'll find this is one of those cases where the terminology may not be precisely applied - the technique I mention above is commonly referred to as triangulation in the GSM location domain. – Observation