05 – Smartphones and sensors

Situm can be used with most Android & iOS smartphones. In this section, we will review what smartphone sensors Situm use, how the smartphone can be carried by the user and the minimum and recommended hardware requirements to have the best experience with Situm.

Operating System compatibility #

Android compatibility #

The following table contains the list of Android versions compatible with Situm.

VersionCompatibility comments
Android 5, 6, 7, 8Not known compatibility issues.
Android 9We recommend using BLE beacons in combination with WiFi networks to achieve acceptable performance.
Android 9 devices limit the capacity to scan WiFi signals (one scan per 30 seconds vs one scan per 1-6 seconds in previous and higher versions). This restriction is called “WiFi throttling”, and it significantly reduces the accuracy when using WiFi.Impedes the WiFi calibration of a building.  
Android 10, 11, 12Android 10 introduced a developer option to deactivate the “WiFi Throttling”. This allows Situm to scan WiFi networks at a normal rate.
This option can be turned on by any user. However, being a developer option it is unlikely that end-consumer users (e.g. users of a shopping mall app) activate it. On the contrary, corporate users (e.g. professional workers using a tracking app) are likely to activate it.
The operation of Situm in Android 11 is similar to Android 10.
We recommend:
For wayfinding apps: use BLE beacons like in Android 9.
For tracking apps: you may use WiFi networks only (no BLE beacons required in general), but only if your users can deactivate the WiFi Throttling.

iOS compatibility #

The following table contains the list of iOS versions compatible with Situm.

VersionCompatibility comments
iOS 8, 9, 10, 11, 12, 13, 14, 15Apple does not allow scanning for Wifi access points. Therefore, it is mandatory to use BLE beacons to achieve an acceptable positioning performance.

Smartphone black list #

SmartphoneReasonAffects Wayfinding, Tracking or both
Nexus 5XCompass issues: orientation may be inaccurate from time to time.Affects both but the effects are not catastrophic.
Samsung S4Gyro issues: orientation may be inaccurate from time to time. Affects both but the effects are not catastrophic.
Any Xiaomi model with MIUIThe MIUI personalization layer prevents continuous positioning in the background unless specific configurations are applied to the smartphone.Only affects tracking use cases. Can be corrected by applying the mentioned configurations.
Any Huawei or Honor model The EMUI personalization layer (under 8)  prevents continuous positioning in the background. However, it is possible to use EMUI 8 if some device settings are changed (contact our Support Team for more information).Only affects tracking use cases. Can be corrected by applying the mentioned configurations.
Any Meizu modelCompass issues: orientation may be inaccurate from time to time. Affects both but the effects are not catastrophic.
Any Huawei (Android 10) Only WiFi throttling can be disabled via ADB.Only affects tracking use cases.

Sensor requirements #

In order to compute the most accurate estimate, Situm fuses all the available sensor information that modern smartphones provide. Not all sensors are required: Situm is always able to make the most of the available information. The following table summarizes how Situm uses the smartphone sensors. You can check the sensors available on your smartphone in GSM Arena.

SensorDescriptionRequired
WiFi and/or BLEWiFi Access Points (WiFi APs) signals can be received by all Android smartphones to provide accurate indoor positioning (after those signals have been mapped through the calibration step).

Similar to WiFi APs, BLE beacons emit wireless signals (Bluetooth) that can be received by all modern smartphones (both Android and iOS). These signals can be captured during the calibration step and used to provide an accurate indoor location. 
Android
BLE & WiFi signals are totally complementary: Situm will work with either of them or with both at the same time. WiFi signals alone are usually enough to provide good positioning accuracy: chances are that you will not need to install any BLE beacon. In this case, BLE beacons are an optional complement for greater accuracy or to enable areas where no WiFi signal is available.

iOS
WiFi signal scanning is not allowed, therefore BLE beacons are required to provide indoor positioning.
GPSThis sensor provides an absolute location (latitude, longitude) within the whole Earth. Sadly, it is not accurate in indoor environments, but the information that it provides can be used outdoors to improve the geolocation estimation provided by Situm, or to provide proper geolocation anywhere in the world, even if Situm technology is not available.Only if you want to achieve outdoor positioning.
AccelerometerThis sensor captures the acceleration that the smartphone experiences. At rest, the accelerometer is only subject to the Earth’s gravity, but when the smartphone moves there will be other forces at play. These forces can be measured in order to estimate how the user moves around the environment.Yes, the accelerometer is always required.
GyroscopeThis sensor measures the angular velocity of the smartphone: that is, the rate at which the smartphone turns. The gyroscope can be used to update the device’s orientation.Not strictly required but highly recommended, since it enhances the accuracy a great deal.
MagnetometerThe magnetometer is the sensor that measures the direction and strength of the magnetic fields surrounding your smartphone. Typically, based on the magnetometer data the Earth’s magnetic field can be isolated, providing the device’s orientation with respect to the North. In this case, we typically call the magnetometer a compass. 
Compass information can be used to determine the device’s orientation, which may play a great deal in enhancing the location accuracy. Raw magnetometer information can also be used to measure the building’s magnetic fields (interferences caused by objects & currents) in order to enhance the location accuracy.
Not strictly required but highly recommended, since it enhances the accuracy a great deal.
BarometerThe barometer is a sensor that measures air pressure. Since the air pressure depends on the altitude, the barometer can help in estimating the floor where the user is in.Not required, recommended to speed up floor transitions.
Summary of how Situm uses the smartphone sensors

Connectivity requirements #

Although Situm uses WiFi and BLE signals to pinpoint the user location, it does not need to connect to them in order to do this: Situm just detects the signal strength without needing to establish a network connection with WiFi APs or BLE beacons. Situm does, however, need to connect to Situm cloud to download the information required to perform the positioning (e.g. signal maps of the building) and to upload some kinds of data, such as the geolocations of the user computed by the smartphone.

We highly recommend using a mobile data network to provide such connectivity. Mobile data networks are usually stable and fast enough to perform all networking tasks required by Situm. Additionally, Situm has been optimized to have a small data consumption footprint. You may check the compatibility of your smartphone with the mobile network of any country here.

On the contrary, on Android phones, we do not recommend using Situm while you are connected to a WiFi network. This is because Situm will scan the WiFi signals while your phone may be communicating through WiFi. This may result in worse WiFi data quality, and therefore in an accuracy reduction. Anyway, if you really need to use Situm while connected to the WiFi network, Situm will still work but with reduced accuracy.

Situm Support validated Android smartphones #


Blackview and Motorola devices are recommended for industrial environments and security while Samsung devices are recommended for corporate use:

ModelOSBatteryGyroCompassAccelerometerBarometerRuggedWiFiSpain price
BV6600Android 108580 mAhYesYesYesNoYes5 GHzFrom 180€
BV4900 pro Android 10 5580 mAhYesYesYesNoYes5 GHzFrom 140€
Motorola G9 PlayAndroid 10, upgradable to Android 115000 mAhYesYesYesNoNo5 GHzFrom 200€
Samsung Galaxy M21Android 10, upgradable to Android 11 6000 mAhYesYesYesNoNo5 GHzFrom 220€
Samsung Galaxy Xcover 5Android 113000 mAhYesYesYesNoNo5 GHzFrom 210€

If the building network does not have 5 GHz, 2.4 GHz smartphones can be used:

ModelOSBatteryGyroCompassAccelerometerBarometerRuggedWiFiSpain price
Motorola G8 PowerAndroid 10, upgradable to Android 11 5000 mAhYesYesYesNoNo2.4 GHzFrom 185€
Samsung Galaxy A21sAndroid 10, upgradable to Android 11 5000 mAhYesYesYesNoNo2.4 GHzFrom 220€

How can you carry a smartphone? #

Situm’s location technology is designed to locate people walking with their mobiles in their hand. However, unlike other indoor positioning technologies, it is also able to operate robustly in the pocket, on a vehicle, etc.

Walking with the phone in the hand #

This is the default and preferred mode of operation for wayfinding. As shown in the following figure, the user carries the smartphone in his hand, with the screen turned on and facing upwards. The smartphone is facing in the user’s walking direction.  

Results are optimal in this situation, usually achieving average accuracies of 1-3 meters. Unlike other location technologies, Situm is also robust against the following user actions:

  1. While standing still, the user is talking on the phone, typing, swinging the smartphone, etc.  Situm is specifically built to detect those situations and distinguish them from the real user movement, enhancing accuracy and robustness. 
  2. Wayfinding while the user moves the phone and changes its position and orientation. As long as the user keeps walking, Situm will be able to correct the deviations introduced by those actions. Sometimes, these actions may result in a momentary accuracy loss (5-20 seconds).

On smartphones that have a magnetometer sensor, it is important to take into account that Situm can not operate correctly if the user walks around with the phone in horizontal orientation (see next figure). In this case, the smartphone’s orientation with respect to the North does not match the user’s orientation, reducing the accuracy of the positioning estimate. If the smartphone does not have a magnetometer, this issue does not exist.

Walking with the phone in the pocket/backpack #

Situm also works perfectly when the smartphone is not in the hand of the user, but in her pocket/backpack/belt. In this case, the accuracy is 1-5 meters on average. This is a bit less than in the ideal case (smartphone in the users’ hand), but nevertheless more than enough to enable tracking use cases: real-time workforce monitoring, heatmaps, etc.

Vehicle tracking #

Situm is also able to track vehicles both indoors and outdoors. The average accuracy is usually 5-15 meters and the typical use case is forklift / AGV tracking in warehouses or industrial plants.

Smartphone cases #

Smartphone cases are typically used in tracking use cases (e.g. security staff positioning). If you want to use them, please pay attention to the following considerations:

  • We advise against the use of smartphone metallic protective covers since they alter the sensor measurements of the device and favor internal heating.
  • In order to avoid overheating, we strongly recommend using a belt case to carry the smartphone.
  • The belt case must be a little bigger than the smartphone.
  • For correct use, the screen of the smartphone should be oriented towards your body. The top part of the smartphone must be in the top part of the case.

Compatibility with tablets #

Calibrating with an Android tablet #

If you want to calibrate your building with an Android tablet using Situm Mapping Tool App, you will be able to do it with any tablet that has the following sensors:

  • WiFi sensor: if you need to capture WiFi signals.
  • BLE sensor: if you need to capture BLE signals.
  • Gyro sensor. This is required by Situm Mapping Tool application to ensure the best experience while calibrating & testing Situm. If your tablet doesn’t have this sensor, contact us (support@situm.com) and we will provide you with a Situm Mapping Tool version that works without gyro.

Wayfinding and tracking in tablets #

Android & iOS tablets can be used in wayfinding & tracking applications, provided that they comply with:

  1. Connectivity requirements as detailed here.
  2. Sensor requirements as detailed here.

Take into account that:

  • If in wayfinding, the user must walk with the tablet in the hand in vertical position (as opposed to landscape position), pointing forward. More details here.
  • In general, walking patterns in tablets are different than in smartphones. Situm is optimized with smartphone data so this may result in a subtle drop in accuracy performance (e.g. 20% error increase).

Recommended settings for Android devices #

Battery Settings #

If your app implements a tracking use case, it will probably need to run for hours in the background. However, by default Android may prevent apps to run for long periods of time in order to save battery. You may disable this Android feature by:

  1. Disabling the Power Saver mode in your smartphone.
  2. Disabling the battery optimization feature for your app.

To find out how to visit the following section.

WiFi scan throttling (Android 9 and onwards) #

In Android 5, 6, 7 and 8, applications can scan WiFi signals once every few seconds (1-3 seconds). This is optimal to provide accurate indoor positioning.

Unfortunately, from Android 9 onwards, Android implements a limitation called WiFi Throttling, which limits the number of WiFi scans to 1 every 30 seconds.  Therefore, Situm receives less frequent data than in previous versions, which means:

  • Reduced indoor position accuracy. Situm is able to provide a location even with this reduced information rate, but you will notice a drop in inaccuracy. 
  • WiFi calibration may not be possible. Calibrating at a rate of 1 scan every 30 seconds can take an unrealistic amount of time.

In order to avoid the effects of WiFi Throttling, we recommend:

Calibration vs positioning

App type

Recommendations

Calibration

Situm Mapping Tool

- Do not use Android 9 smartphones.
- If you use an Android 10 or superior smartphone, remember to disable WiFi Throttling both in your smartphone (see below) and to enable the "Ignore WiFi Throttling" option in Situm Mapping Tool.

Positioning

Tracking apps

- Do not use Android 9 smartphones.
- If you use an Android 10 or superior smartphone, remember to disable WiFi Throttling both in your smartphone (see below) and to enable the "Ignore WiFi Throttling" option in Situm Mapping Tool.

Wayfinding apps

Use beacons as a complement to WiFi network. This should not be an issue because you may have to use them anyway if you plan on providing wayfinding services to iOS devices as well.

Android 9 does not allow you to disable WiFi Throttling, but in Android 10 and superior versions, you may do it. If you do so, everything will work just fine (same accuracy as in Android 5, 6, 7 or 8). This is especially relevant for tracking applications, which typically target Android devices (not iOS devices). Once they disable WiFi Throttling, these apps will work with WiFi-only infrastructure, avoiding the installation of beacons.

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