In response to developments in Location Based Services and concerns regarding privacy, Apple introduced Random Mac Address in iOS8 to hide device’s actual MAC from Wi-Fi negotiations.
Since then, Random MAC Address has also been adopted by Android and Windows. While the mechanisms and triggers of the Random MAC Address differs from vendor to vendor, (for example, only in Windows 10 can Random MAC Addresses be enabled or disabled by the user) it can be safely assumed that whenever a Wi-Fi device is probing for Wi-Fi networks, it is probing with a Random MAC Address. In all cases though, if the WiFi device decides to associate with the Wi-Fi service (guest SSID or employee SSID e.g.), then the device uses the actual MAC for the duration of the Wi-Fi session.
A single Wi-Fi device may send out multiple Random MAC Addresses while probing for Wi-Fi networks. This further reduces the ability for Wi-Fi based location technology to track the WiFi device across time due to a lack of a common identifier for a single WiFi device.
When observing the effects of the Random Mac Address on Omaya Analytics, we found that it skewed the numbers for Unique Devices detected, New vs Repeat count and Dwell Time.
Omaya was able to detect and position 50%-70% of Wi-Fi devices in Omaya deployments. The percentages depend on factors such as reliance on WiFi in the country, the type of deployment (transport vs retail), smart phone penetration etc. Going forward, the number of Wi-Fi devices that Omaya can detect and position move towards the percentage of associated WiFi devices. This is currently estimated to be 20%. Again, depending on factors specific to the deployment.