Everything you need to know about location tracking.

Blog Published 2017-04-04

Most people have probably tried services to view their own, their families or friends location via GPS in their smartphone. This seldom work indoors or meet mission critical requirements. So what are the alternatives for tracing lone workers or managing resources?

Applications

In order to utilise the collected location data, some kind of software is needed to decode the information, especially if the positions are to be tracked from a remote location. Software design and features may vary depending on the current application, purpose and tracking method.

Enterprises protecting lone workers might settle with present location data in plain text to managers and co-workers in case of emergency. Utility companies managing resources remotely probably need a map-centric application, possibly with the addition of building layouts. For stores analysing customer flows basic tables or heat maps might fit the bill. Warehouses tracking goods likely need an integration with current inventory management system while zoo’s that want to make their visitors experience more interactive require a tailored smartphone app.

Positioning outdoors

Outdoor positioning is usually managed by GNSS, Global Navigation Satellite System. For most people this is synonymous with the American GPS but, Russia and China actually also have working GNSS named Glonass and Beidou. The EU are also working on their own system under the name Galileo but it is not yet operational.

The systems are set-up very similar, using a form of triangulation. Satellites continuously transmit signals containing their own location and direction bundled with a timestamp. Since the receiver knows how long the signal has travelled, it can use the satellite as a point-of-reference. Using four or more satellites, the device can calculate its own location and present the data locally or forward it as coordinates.

By being connected to a network of control stations on earth, the satellites can keep track of their own location in a similar way. All system components are also synchronised to enable them to calculate distances and locations using an exact point-in-time and the constant speed of light.

Positioning indoors

To determine positions inside, out of reach of GPS signals, a number of technics are available where precision, range and/or ready available devices determine the best fit for current application.

Bluetooth

In recent years Bluetooth positioning has become increasingly popular thanks to the Bluetooth Low Energy (BLE) protocol enabling a range of new applications. In general, there are two types of Bluetooth based positioning solutions, server-based and client-based.

A server-based system uses receivers to detect Bluetooth-enabled devices in its vicinity. The receivers then forwards the information to a computer over the LAN, as long as the device in within reach. Since the system distinguishes between the devices by its own, basically all Bluetooth-enabled devices can be used. Even devices without any native intelligence, like ID card holders with integrated Bluetooth.

By adjusting the number, placement and settings of the receivers the required precision can be provided, varying from entered buildings to a specific point in a room. The technic is highly reliable and is particularly suitable for tracking lone workers, managing resources remotely or to track unauthorized movement.

The client-based method instead uses a network of Bluetooth beacons that continuously transmit a signal that is registered by the user device. The information can then be forwarded to a computer using the device ordinary data connection (3G, LTE, Wi-Fi, two-way radio).

These battery-powered beacons are cheap and easy to place since they do not require any external connection. Instead, all tracked devices are equipped with a dedicated app to navigate and transfer location to the computer. In a client-based system, there is also a risk that the data load gets too heavy on the connection, depending on the amount of location data that is being sent.

The solution is suitable for providing museum visitors with information about nearby exhibits or for navigating large venues, in their own smartphones.

RFID

Radio Frequency Identification (RFID) works like barcodes where the lines have been exchanged with a weak magnetic field. A passive RFID-tag (barcode) lacks internal power supply, making them small enough to fit into a regular price tag. Instead, the RFID readers provide enough current through induction to enable the tag to transmit a weak signal. When a tag passes a reader the event is logged an sent to a computer.

Unlike the other methods, passive RFID does not provide real-time location tracking since only changes are registered. The readers are also relatively expensive and limited range making it challenging to provide high precision. RFID tags can also be active, meaning they have an internal power supply. This method is similar to server-based Bluetooth system, besides that RFID requires dedicated tags.

Applications vary from tracking in- and outgoing packages in warehouses, tagging animals or anti-theft protection in stores.

Wi-Fi

Wi-Fi positioning solutions (WPS) use the device Media Access Control (MAC) address and Received Signal Strength Indicator (RSSI) to calculate approximate distances to access points. WPS typically has range but the precision is rarely high and varies with the number of access points. The systems are also typically server based, requiring a dedicated app.

A WPS can be used for roughly the same things as a client-based Bluetooth system but is especially suitable if an extensive WLAN already exists and the devices you wish to track are WLAN enabled.

More methods

You can actually install GPS repeaters to provide equivalent functionality indoors but even in the best case, you only see your horizontal location. That works fine in a tunnel but does not help much in a skyscraper.

Recently concepts for that use visible light for positioning have been demonstrated. These so called VLC, Visual Light Communication, systems use LED lights and other lighting to determine positions. However, these are not yet market mature, so we will have to get back to them later.