06 – Infrastructure: WiFi & BLE

Situm uses WiFi and BLE to pinpoint the user’s location inside buildings. In this section, we will explain the most important factors that you may take into account regarding your WiFi & BLE infrastructure.

WiFi infrastructure #

Most buildings have a WiFi infrastructure in place. In Android, Situm is able to read the strength of WiFi signals already available in these buildings in order to determine the user’s location. Sadly, iOS does not allow reading WiFi signals and therefore WiFi can not be used to provide indoor positioning with them.

WiFi density requirements #

Situm can work accurately with most WiFi network settings found in buildings. In fact, Situm can provide indoor positioning even in areas where only one WiFi Access Point can be heard. As a rule of thumb, if in a certain area three or more Access Points (AP) can be detected, Situm accuracy will be in the range of 1-4 meters on average.

Anyway, 99% of the time you will not have to worry about WiFi density: Situm will just work. If it doesn’t work properly in some specific areas, installing a few beacons to complement the WiFi signal will be enough.

Using WiFi for communications and navigation (Android only) #

Sometimes, being connected to a WiFi network may interfere with Situm’s WiFi scanning for positioning purposes.  The effects can range from a slight decrease in the positioning accuracy to a temporal blockage of the WiFi chipset (after which Situm will not be able to use WiFi to compute locations for a while). This only applies to Android devices, since on iOS devices Situm positioning does not use WiFi signals.

For these reasons, in Android devices, we recommended disabling WiFi connectivity on your smartphone during positioning and/or calibration (you may do this using your smartphone settings menu). Keep in mind that the smartphone will need an active mobile data connection to exchange information with Situm Platform.

If you really need to use WiFi communications concurrently with Situm, you have 2 options:

  • Use BLE beacons.  In addition to WiFi, Situm is also able to provide location by using Bluetooth, in case BLE Beacons are installed. The default behaviour is to use both WiFi and Bluetooth, but you can decide whether to use only one of them, or both.
  • Just don’t follow this recommendation. Even with the smartphone connected to the WiFi network, most users will get a good performance. Anyway, keep in mind that in some smartphone models a temporal blockage of the WiFi chipset might occur (after which Situm will not be able to use WiFi to compute locations for a while).

Dealing with WiFi infrastructure changes #

WiFi Access Points (APs) may change after a building has been calibrated. Some of them will be removed, some new ones will be installed… Situm is pretty robust to these changes:

  • Introducing new WiFi APs. New WiFi APs will have no effect at all. Optionally, you may recalibrate to gather these new signals and make the most of them (usually leading to a higher accuracy), but this is not necessary. If you do recalibrate, make sure that you cover all the areas where the new access points can be heard (this may include, of course, different floors).
  • Removing WiFi APs. Situm will usually keep working until you remove 50-70% of them. This is, of course, provided if you have sufficient coverage in the first place.
  • Changing the place of WiFi APs. This may produce unexpected errors, and therefore should be done with care. First of all, please inform our Support Team (support@situm.com) so that we can manually remove these APs from your original calibrations. After that, if you want to use the signals of theses APs in the new areas were you have installed them, you will need to recalibrate those areas.

Dealing with MAC-changing WiFi APs #

Some routers are configured to change their MACs periodically. Situm can handle this kind of infrastructure, but we must perform a few configurations for your first. Please contact our Support Team (support@situm.com) and we will be happy to assist you.

Managing WiFi infrastructure #

Once the building is calibrated, changing some Wi-Fi APs will not affect the working system. Situm is pretty robust to antenna changes:

  • Adding new antennas. Situm will keep on working. Optionally, you may recalibrate to make the most of the new antennas (more accuracy), but this is not necessary.
  • Removing some antennas. Situm will usually keep working (until you remove 50-70% of antennas of that area), no recalibration is required. This is, of course, provided if you have sufficient coverage in the first place.
  • Changing the place of some antennas. You may need to recalibrate only the affected areas. Optionally, we may disable those antennas in our backend, so they do not affect Situm (situation number 2) and no recalibration is required.

BLE beacons #

Bluetooth Low Energy (BLE) beacons are an amazing technology.  In case you don’t know them, they are small devices that broadcast their identifier using Bluetooth technology. By this way, they enable smartphones, tablets and other devices to perform actions when they are in close proximity to them. 

Beacon compatibility: iBeacon #

Situm is compatible with any beacon that emits BLE signals using the iBeacon Protocol, since this is the most common, standard, and widely used protocol. Other protocols, such as Eddystone, can not be used with Situm: however, it is usually easy to configure Eddystone beacons to emit in iBeacon protocol.

An iBeacon advertisement provides the following information:  

FieldSizeDescription
UUID16 bytesThis is an identifier that can be shared among many beacons. Usually, you will want to assign one UUID to all your beacons. Situm can be configured to detect specific UUIDs.
Major and Minor2 + 2 bytesTogether, major and minor act as the unique identifiers for your beacon.

Does Situm require the use of BLE beacons? #

In general, the answer is no. However, it really depends on some aspects, like the OS and its version and mainly if the building has other broadcasting resources. You can check this information here:

Operating System  Does Situm require beacons? Could beacons improve accuracy?
Android No. Situm will work accurately if the building provides a Wi-Fi network.

Except for Android 9 for which, by now, the use of beacons is necessary.
Yes. Beacons can help to achieve high accuracy in areas where the Wi-Fi signal is weak.
iOSYes. Unfortunately, iOS does not allow retrieving the smartphone Wi-Fi scans, so Situm must rely on BLE signals to locate the smartphone accurately.Yes. Beacons are used to set the primary location and to correct the positioning estimation periodically.

How many beacons do I need to use? #

It depends on the building distribution as well as on the transmitting characteristic of the beacons. For a typical configuration using an advertising period of 750 ms and transmission power of -4dBm or 0dBm:

Type of building Minimum beacon density Recommended beacon density
Open space1 beacon per 625 square meters (25×25 meters)1 beacon per 400 square meters (20×20 meters)
Corridors1 beacon for each 30 meters1 beacon for each 20 meters

In addition, we do not recommend placing beacons at a height higher than 4 meters. 

Configuring your beacons #

By default, Situm Mapping Tool and Situm SDK only detect beacons configured with Situm’s UUID 73697475-6D73-6974-756D-736974756D15 and Kontakt’s UUID f7826da6-4fa2-4e98-8024-bc5b71e0893e. If yours are not in these, enter them as follows.

These are the most important parameters that you should configure:

Parameter Description Recommended value
Advertising periodThe interval between consecutive broadcasts750ms

This will allow Situm to retrieve enough BLE frequency to provide good accuracy while being able to extend the beacon battery time.
Transmission powerThe beacon power to broadcast the BLE signalBetween -4 dBm and 0 dBm (0dbm is indicated for all the spaces, except floor plan transitions, where -4dbm is the most recommendable).

This will ensure that the beacon is received at a range between 15 meters (-4dBm and 0dBm).
UUIDUniversally Unique Identifier that allows you to distinguish your own beacons from all the other beacons that aren’t by your control. Usually, all the beacons from the same dealer will have the same UUID, thus when you order the beacons you will be assigned a unique UUID. If you want to use other beacons than the ones provided by Situm, you just have to create a custom field in your building with:
– Key: beacons_uuids
– Value: your UUIDs separated by commas (e.g. 00000000-0000-0000-0000-000000000001, 00000000-0000-0000-0000-000000000002).This value SHOULD NEVER be 00000000-0000-0000-0000-000000000000.
This is used by default in electrical household appliances (TVs, Bluetooth cars, etc.).

Knowing your beacon’s UUID #

Knowing your beacon’s UUID is very easy! You just have to download a beacon scanner application from Google Play or Apple Store. Most of them will be able to scan beacons around you and give you their UUID. For example, you may use the Beacon Scanner app :

click the blue play button at the bottom right

  1. In the main screen, just click the blue Play button (left screen) at the bottom right and it will start scanning.
  2. After a few seconds, beacons will appear. You will be able to see different beacon parameters, such as signal power, major, minor and UUID. 
  3. You should notice that most beacons have the same UUID.

Placing beacons in your building #

Where & how to place them #

Beacons can be installed on the walls, ceilings, or other elements of your building. Usually, you will be able to attach them through an adhesive that they carry on their back part (some beacons also allow you to screw them).

We recommend not installing them near sources of electromagnetic emissions, such as WiFi APs, operating machines or electrical panels. We also suggest placing them at between 2.5 and 4 meters.

Beacon distribution: open areas, corridors and small rooms #

As a general rule, you should distribute your beacons so that you:

  • Cover as much space possible while respecting at least the minimum number of beacons recommended.
  • All areas are covered at least by the signal of 2-3 beacons.
  • The imaginary perimeter formed by the outer beacons of each floorplan encloses all the areas that you want to cover.

More specifically, follow these tips for placing beacons in the section How to place beacons.

Optimizing beacon placement for floor detection #

There are some cases, mainly offices in large buildings, that the distribution may be assorted. If your building has more than one floor, it is important to place the beacons close to the floor changing points (elevator, stairs) in order to provide the best floor detection accuracy. 

Recommended vendors and models #

Situm was designed to work with any beacon available in the market and nowadays, to our experience, there are plenty of vendors that produce high-quality beacons with different characteristics and price ranges.

However, two brands have stood out for us because of their good quality/cost ratio: Accent Systems and Kontakt.io.

ACCENT SYSTEMS

iBKS is a Bluetooth Low Energy family based on Nordic Semiconductors nrf51822 chipset.

The three protocols that beacons comply with are iBeaconTM , EddystoneTM (UID, URL, TLM & EID), and Firmware update over the air.

iBKS family has FCC Certification (USA) and CE Certification (EU).

Beacons are provided out of the box with custom configuration, but all parameters can also be modified through the iBKS Config Tool App (available for iOS and Android).

MODELTX POWER (dBm)BATTERY LIFETIME
(depending on Tx power and interval)
RANGE OF COVERAGESENSITIVITYUSEFUL RESOURCESRECOMMENDED USES
iBKS 105[-30 dBm / +4 dBm]Replaceable – Up to 46 monthsUp to 50m
(We recommend to limit the range to 40m or less) 
Up to -102 dBmiBKS 105 DatasheetIndoor & outdoor positioning with smartphones
iBKS Card[-40 dBm / +4 dBm]Replaceable – Up to 18 monthsUp to 100m 
(We recommend to limit the range to 90m or less) 
Up to -92 dBmiBKS Card DatasheetIndoor asset tracking
iBKS Plus[-30 dBm / +4 dBm]Replaceable – Up to 104 monthsUp to 100m 
(We recommend to limit the range to 90m or less) 
Up to -102 dBmiBKS Plus DatasheetIndoor & outdoor positioning with smartphones
iBKS USB[-30 dBm / +4 dBm]Works as long as it is pluggedUp to 100m
(We recommend to limit the range to 90m or less)  
Up to -102 dBmiBKS USB DatasheetIndoor & outdoor positioning with smartphones
iBKS 105
iBKS Card
iBKS Plus
iBKS USB

KONTAKT.IO

Kontakt.io is a Bluetooth Low Energy family based on Nordic Semiconductors nRF52832 chipset.

The three protocols that beacons comply with are iBeaconTM , EddystoneTM (UID, URL, TLM & EID) and Firmware update over the air.

Kontakt beacons have FCC Certification (USA), CE Certification (EU) and RoHs Certification.

It is quite simple to identify all Kontak.io beacons because of their ID number and their administration can be done with Kontakt.io Panel or App (available for iOS and Android).

More information on: Kontakt.io Secure – FAQ

MODELTX POWER (dBm)BATTERY LIFETIME
(depending on Tx power and interval)
RANGE OF COVERAGESENSITIVITYRECOMMENDED USES
TAG S18- 3[-20 dBm / 4 dBm]Replaceable – Up to 20 monthsUp to 50m
(We recommend to limit the range to 40m or less)
Up to -96 dBmIndoor asset tracking
TOUGH TB15-1[-30 dBm / 4 dBm]Irreplaceable – Up to 30 monthsUp to 70m
(We recomend to limit the range to 60m or less)
Up to -93 dBmIndoor & outdoor positioning with smartphones
PRO BP16-3[-20 dBm / 4 dBm]
Replaceable – Up to 96 monthsUp to 70m
(We recommend to limit the range to 60m or less)
Up to -96 dBmIndoor positioning with smartphones
TAG S18-3
TOUGH TB15-1
PRO BP16.-3

If you’re still unsure about purchasing beacons, please send an email to sales@situm.com and we will be happy to guide you towards choosing the best ones for your need.

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