WiFi for Indoor Positioning

Picture of an indoor floor plan on top of a pattern of WiFi symbols
Illustration: © IoT For All

This text discusses the usage of WiFi for indoor asset tracking. Whether or not or now not you may well be at your local coffee retailer, space, or place of work, WiFi is in every single place. Being able to apply belongings the usage of WiFi may well be very exciting given that group infrastructure is already ubiquitous and standardized. WiFi networks are reasonably inexpensive, easy to prepare, and inconspicuous. For spacious indoor puts where GPS is fallacious, WiFi provides a actually best selection. We can be taking a deeper dive into what WiFi is and the best way indoor positioning strategies leverage WiFi connectivity.

What Is WiFi?

WiFi describes a space wireless group that uses radio waves to keep up a correspondence knowledge, maximum regularly from the Internet. To be thought to be WiFi, the radio signal will have to use the IEEE 802.1 same old to keep up a correspondence. There are a couple of permutations of WiFi as defined inside the IEEE specifications, which include now not odd ones paying homage to 2.4 GHz and 5GHz frequency radio waves. WiFi is maximum regularly used to modify large amounts of information. It has transfer speeds of up to a variety of gigabits in keeping with second evidently permutations.

How Does WiFi Observe Location?

There are a couple of methods for tracking an indoor WiFi-enabled asset. The two primary methods are RSSI and fingerprinting. RSSI (or Gained Signal Energy Indication) of a WiFi signal is inversely proportional to distance. At the side of trilateration, RSSI can be used to approximate an asset’s location. Alternatively, the measured RSSI of an indication can be  decreased on account of obstructions and/or reflections, leading to erroneous RSSI measurements and, therefore, location determinations.

A method referred to as fingerprinting can be used to beef up this accuracy significantly. Fingerprinting uses historic RSSI wisdom along with identified puts to come to a decision the site of an asset given its provide RSSI values. Fingerprinting could be very dependent on the atmosphere, so if a chair or table is moved, the fingerprint will need to be up-to-the-minute. Together with RSSI and fingerprinting, Point of view of Arrival (AoA) and Time of Flight (ToF) can be used to come to a decision location. While the ones methods are proper, they require pricey equipment and techniques paying homage to a couple of antennae and clock synchronization.


The important thing advantages of WiFi are accessibility, large range, and a most sensible knowledge throughput price. WiFi may be widely available. In some instances, there may be a variety of WiFi get right of entry to problems in a room or floor. Generally, the additional WiFi get right of entry to problems there are, the higher the accuracy of the indoor tracking may also be. For some applications, there might be little to no infrastructure costs for implementing a WiFi group for asset tracking. Additionally, WiFi has an excessively long range up to 150 meters, which is excess of Bluetooth. Compared to Bluetooth, WiFi moreover has a a long way higher knowledge transfer, which might be useful if the asset should transfer a large amount of knowledge (e.g. pictures, video, or uncompressed audio).


Probably the most primary disadvantages of WiFi is its accuracy. With an accuracy at the higher end of 15 meters, it’s going to now not be as suitable for precise location applications, where Bluetooth excels by means of comparison with its 2-4m accuracy. Alternatively, accuracy can be as low as 2-3m with fingerprinting, a very important amount of WiFi get right of entry to problems, and/or combining tracking knowledge with other technologies (regularly known as sensor fusion). Oregon State School, in collaboration with Intel, is working on SAIL, a WiFi indoor tracking technology that “achieves a location accuracy upper than 1m.” Each different downside of the usage of WiFi is protection issues. WiFi is this type of now not odd technology that it has already professional numerous hacks and resulting protection patches. Protection will all the time be a concern for WiFi, alternatively given this, there will all the time be corporations operating to harden WiFi from malicious attacks.


WiFi is evidently a viable resolution for indoor asset tracking. For a trade place of work, purchasing groceries mall, or school campus, WiFi generally is a best low value technique to apply belongings indoors. While accuracy and protection issues would perhaps impede WiFi, the ones drawbacks can be mitigated the usage of ways paying homage to fingerprinting, sensor fusion, and protection hardening. Hopefully, indoor tracking may also be further prevalent given the preferred use of WiFi. 

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