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Sensoro Class: How does iBeacon realize positioning?

This passage elaborates to you the working principles and positioning solutions of iBeacon—a new position sensing technology, through the commercial practices of Sensoro engineers.

In iOS7, Apple introduces a new position sensing technology”iBeacon”, which is seen as an alternative for GPS in indoor positioning.

What is iBeacon?

iBeacon is a signal broadcast device using BLE Low Energy. Every device has a unique ID(UUID+Major+Miner), which enables iBeacon to broadcast its own signal and mark specific regions. When users are at proximity to iBeacon regions, related Apps will waken be taken. With the help of an iBeacon, a smartphone can pinpoint the user’s changes to physical locations or whether certain Apps should wake. Currently, Apple provides complete support in iOS SDK to realize the mentioned functions.

How to measure distance?

We use RSSI value to show the signal strength of iBeacon. Like other wireless signals, RSSI values change with the distance. We can identify if the user is near or far away with the help of RSSI value. The distance (in meters) between end users and iBeacon can be directly read from Accuracy available on iOS SDK.

The following figure shows the distance measured are 1m and 4m.

Sensoro finds in practice that distance measurements are not always accurate due to the fluctuation of signals and complex environmental factors of the physical world. Apple defines four range values:

  • Immediate. Very close, less than 1 m。
  • Near. About 1-3m.
  • Far.
  • Unknown. Often occurs in startup or unidentifiable due to some reasons.

One thing to be noted Far doesn’t definitely equal to a long distance from iBeacon. It’s highly likely that we are very close to an iBeacon (e.g. 1m), but can not be proved by enough data. So here Far only suggests a large range with the device being anywhere in it.

Sensoro’s practice: Positioning solutions

Poisoning accuracy of traditional GPS is around 10m, while iBeacon can reach 1 to tens of meters. In this sense, iBeacon is superior to GPS. GPS can locate targets in a range within bigger errors, e.g. in certain buildings. iBeacon can identify if the user is near to some location and the distance from it. Sensoro will discuss with you about different positioning solutions in the following part.

Solution 1: Single-spot positioning

The coordinate of iBeacon within Near will be marked when identified. This method guarantees higher accuracy in case of intense deployment of iBeacons, e.g. positioning coffee tables. The indoor positioning of lower accuracy (acceptable within 5m) can also be realized, e.g. identifying the current location in shopping malls. This solution requires the minimum of the deployers.

Solution 2: Two-spot positioning

Deploy two spots on one line. When the user is between the two spots, we can calculate the distances ratio using RSSI formula so as to tell the user’s position. X/Y = n; the user is at one hyperbola area, and then the location can be determined by Accuracy Value from the nearest iBeacon. This solution requires experienced deployers and is suitable in narrow spaces, such as corridors.

Solution 3: Multi-spots positioning

Sensoro can figure out the coordinate location of users after recording the coordinates of every spot and after complex calculations using RSSI values. This solution requires the maximum of deployment and suitable for empty rooms.

To sum up, in current Sensoro practices, the single-spot positioning solution is most widely used with minimum difficulty and adjustable positioning accuracies. Position identification and mutual interaction are of great practice importance in coffee shops and museums. While multi-spot positioning is mostly applied in spacious rooms where the user’s rough location can be timely recorded, but this method is comparatively difficult, plus there might be some signal blockages by indoor objects. So support from professional personnel is necessary for implementation.

Sensoro’s suggestion: single-spot positioning is the most desirable solution in indoor positioning. Lack of accuracy can be fixed by deployment density and the two-spot solution can be added where the need for accuracy is not high.

Difficulties in iBeacon implementation

  1. iBeacon’s deployment locations (map coordinates) need to be recorded. No blockage over signals.
  2. Signals will always more or less be affected in physical environments; hence multi-spot positioning method is highly challenged.
  3. To ensure iBeacon’s proper functioning, we should always consider the issues of routing inspection, anti-theft, repairmen and so on.

Summary

As an emerging new position sensing technology, iBeacon surely bears a promising future. Though we still have a long way to go, with the development of technology and improvement of the ecosystem, Sensoro holds the faith that iBeacon will someday change the world.

Follow Sensoro, you are welcome to the world of iBeacon!

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