Tools to determine exact location when using ibeacons

Question

We are working with a Retail client who would like to know if using multiple iBeacons throughout the store would help track a customer\'s exact location when they are inside the

Answer 1

When discussing positioning, you need to first define your needs more concretely.

Computer/GPS geeks will assume you want accuracy down to the millimeter, if not finer, so they will either provide you with more information then you need - or tell you it can't be done[both viable answers].

However, in the REAL WORLD, most people are looking for accuracy of at most 3 feet[or 1 meter] - and most likely are willing to accept accuracy of within 10 feet[ie visual distance].

iOS already provides you with that level of accuracy - their api gives you the distance as "near, medium, far" - so within 10 feet all you need to check is that the distance is "near" or "medium".

If your needs go beyond that, then you can provide the custom functionality quite easily. You have 32 bits of information[major and minor codes] That is more then enough information to store the lattitude and longitude of each ibeacon IN the beacon itself using Morton Coding, http://www.spatial.maine.edu/~mark.a.plummer/Morton-GEOG664-Plummer.pdf

As long as altitude[height] is not a factor and no beacon will be deployed within 1 meter of another beacon - you can encode each lat/long pair into a single 32 bit integer and store it in the major and minor code.

Using just the major code, you can determine the location of the beacon[and hence the phone] to within 100 meters[conservatively]. This means that many beacons within the same 100 meter radius will have the SAME major code.

Using the minor code, you can determine the location of the beacon to within 1 meter, and the location of the phone to within 10 feet.

The code for this is already written and widely available - just look for code that demonstrates how it is "impossible" to do this, ignore what the comments about it not being possible since their focused on precision to a greater degree then you care about.

**Note: as mentioned in later posts, external factors will affect signal strength - but again this is likely not relevant for your needs. There are 3 'distances' provided by the iphone sdk, "close, near, far".

Far is the problematic one. Assume a beacon with a 150 foot range. Check with an iphone to determine what the 2 close distances are ideally... assume within 5 feet is "close" and 15 feet is "near".

If phone A is near to Beacon B[which has a known location] then you know the person is within 15 feet of point X. If there is a lot of interference, they may be 3 feet away, or they may be 15 feet, but in either case it is "within 15 feet". That's all you need.

By the same token, if you need to know if they are within 5 feet, then you use the "close" measurement.

I firmly believe that 80% of all positioning needs is provided by the current scheme - where it is not then you do your initial implementation with the limitation as a proof of concept and then contact one of the many ibeacon experts to provide the last bit of accuracy.