Why is choosing a WiFi sensor a bad idea?

For several years now, many institutions open to the public (train stations, shops, shopping centres, museums, local authorities, etc.) have been turning to WiFi people counters to measure their visitor numbers. This device has many advantages, but also some disadvantages that public places may not necessarily be aware of... What's more, there are many other counting systems capable of managing and analysing your people flows more accurately and efficiently!

Let's start by reviewing how WiFi counting works and its advantages, before moving on to the significant disadvantages it can entail. We will finish by revealing the many alternatives available on the market.

Discover our guide to counting systems

WiFi counting sensors: how do they work?

The WiFi sensor works by detecting signals emitted by mobile devices connected to a WiFi network: this is the basic operation of smartphones, which are constantly searching for a WiFi hotspot to connect to. Each smartphone therefore constantly ‘calls silently’, and it is this call that WiFi sensors detect and count. It should be noted that this terminal detects signals emitted by smartphones connected to the public WiFi network.

WiFi hotspots are very easy to install, as they only need to be plugged into an electrical outlet. There are no restrictions on where these hotspots can be placed; they can be plugged into any available electrical outlet as long as they are located within the measurement area. This is therefore an inexpensive solution that is very easy to deploy, but it also has many disadvantages...

The data collected by WiFi sensors can be used to measure the performance of a public place, such as the number of people present at a given time or attendance trends. This information can be used to improve the welcome, comfort and experience of your visitors and also to optimise your organisation by adjusting your employee schedules and opening hours.

WiFi traffic counters: what are the disadvantages?

As mentioned above, WiFi beacons can be deployed relatively easily, but the data collected is moderately representative and inaccurate... They cannot count people more than 20 metres away and, on average, only use 20% of visitor traces.

This is because the number of people connected to a WiFi network does not necessarily correspond to the number of people present in a location. Some visitors may be connected to other WiFi networks, using mobile data or simply not have smartphones (usually children or elderly people). All these people will therefore not be counted, resulting in inaccurate results that do not reflect the actual footfall in the location. Furthermore, WiFi sensors cannot distinguish between people entering and leaving a location, which can lead to double counting.

It is also important to note that WiFi sensors are now relatively obsolete: most mobile operating systems have implemented an address randomisation system that makes it almost impossible to count them... The same device can change its address randomly and therefore be counted several times. In addition, WiFi sensors can be easily bypassed using tools such as VPNs or virtual private networks. These tools can hide the user's actual location and distort the results. Finally, we have no knowledge of the frequency of WiFi requests sent by smartphones, so a person could potentially have travelled several hundred metres between two requests.

Furthermore, WiFi counting beacons cannot provide detailed information about individuals present in a location, such as their purchasing behaviour or demographic profile. For example, they are unable to distinguish between adults and children, or between adults and animals.

It is also important to note that the use of WiFi sensors may violate the privacy of users by collecting data about their location and browsing behaviour. This can lead to privacy and regulatory compliance issues.

Although WiFi people counting seems to be a convenient method for measuring footfall in a location, there are many drawbacks to this approach, including inaccurate results that call into question the accuracy and reliability of the data collected, easy workarounds and privacy issues. It may therefore be preferable to use other methods of measuring footfall that do not rely on visitors' smartphones.

What are the effective alternatives to WiFi counting?

There are several alternatives to WiFi counting for measuring your footfall: on the one hand, there are technologies that are independent of smartphones but dependent on visitor equipment, such as iBeacons and RFID (Radio Frequency Identification) tags; on the other hand, there are technologies that are independent of both smartphones and visitor equipment. We have chosen to present only these technologies because they are the most effective on the market.

Infrared sensor

An infrared sensor counts visitor entries and exits by installing two small boxes between which two parallel infrared beams are emitted. This device is very easy to install and is particularly autonomous, as it runs on simple AA batteries, so no wiring is required.

However, its accuracy will be lower during busy periods or in wide passages (greater than 5 metres), so if this is the configuration of your institution, the infrared sensor is not the technology to choose! Furthermore, it is not capable of differentiated counting, so if you want to differentiate between adults and children, animals or pushchairs, for example, you will need to look for another technology.

AI Sensor

The AI Sensor is a device for counting people and objects. Placed at a height, it detects and analyses shapes in its ‘field of vision’, identifies those that can be assimilated to human beings, vehicles or animals in order to track them, and counts all those that cross a predefined virtual counting line. It then transmits updated counting data every minute via the 3G/4G network.

The most powerful AI sensors can estimate occupancy, traffic and waiting times simultaneously!

This device is relatively easy to install as it only requires a power supply and access to the 3G/4G network. The data collected by this sensor is representative and very accurate! In addition, it can be adapted to all types of structures, including open spaces such as nature parks.

3D video sensor

The 3D sensor is a system that uses stereoscopic video technology to provide a 3D view of the point of passage it is measuring. Placed directly above the passageway, it counts all the people in its capture zone in order to track their movement, and counts all those who cross a predefined virtual counting line.

It is known for its high accuracy and its ability to count high traffic and adapt to the most complex locations. However, its installation can be a little more complicated than the sensors mentioned above as it requires POE cabling.

Video surveillance

It is also possible to use cameras already present on a site to perform counting. The video sequences are simply used to perform the counting using powerful algorithms. All you need to do is install the video analysis logic unit in the network rack and connect it to the video concentrator.

However, the quality of the counting depends on the viewing angles, the quality of the available video stream and the brightness of the video surveillance system installed. It is therefore important to carry out an initial diagnosis with an expert on the subject in order to confirm the technical relevance.

Would you like to be assisted by a flow management expert to choose the best device? Contact us!