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Bluetooth Low Energy
The advantage of passive BLE
Bluetooth Low Energy protocol was developed by Ericsson AB to support wireless communication by battery-powered IoT devices. Battery-powered devices were the peripherals that spontaneously announced their status by broadcasting advertisements. Smartphones were the central devices that passively listened for these advertisements.
The advent of Apple’s Continuity Protocol changed everything and is the basis of advanced Apple services like Find My, Handoff, and Airdrop. These services caused smartphones to behave like peripherals and to advertise their presence incessantly: typically once each second. This new behavior made audience measurement possible with BLE–at least those members of the audience who carry iPhones.
Because smartphones broadcast advertisements typically every second, BLE is a good solution for audience measurement when dwell times are short or signage viewsheds are small. Because only iPhones broadcast advertisements and the maximum detection range of BLE is only one tenth that of Wi-Fi, BLE is a complement to Wi-Fi for retail media and digital signage applications. To learn more about the advantages and uses of passive Wi-Fi measurement visit this page.
| Technology | Wi-Fi | Bluetooth Low Energy (BLE) |
|---|---|---|
| Share of smartphones that broadcast | 100% of smartphones probe | 100% of iOS smartphones advertise, but very few Android smartphones advertise |
| Maximum detection distance (can be reduced through calibration) | Up to 300 feet (100 meters) with standard antennas. | Up to 30 feet (10 meters) with standard antennas |
| Median inter-arrival time of smartphone broadcasts | 32 seconds median | 1.2 seconds median (for iOS only) |
| Lifetime of randomized smartphone addresses | 8 hours median (for local MAC addresses) | 4.1 minutes median (for iOS only) |
| Chaining of broadcasts across address rotations | Chaining not highly relevant due to long local MAC address lifetime Long local MAC address lifetime makes in-store shopper journey easy | Chaining possible, but technique is fragile: (1) best in low occupancy zones, (2) requires continuous sensor coverage and (3) Apple payloads are proprietary and can be obfuscated (to prevent chaining) in any future OS release |
| Utility based on people present | Excellent accuracy in zones with long dwell times (e.g. slow-moving phones, large zones) Poorer measurement accuracy in zones with short dwell time (e.g. fast-moving phones, small zones) | Excellent measurement of dwell times below 1 or 2 minutes (e.g. fast-moving phones, small zones) Poorer measurement accuracy in very low occupancy environments (e.g. small panels). Non-iOS smartphones are not detected. |
While passive Wi-Fi delivers exceptional performance across large coverage areas, passive BLE is better for measuring audiences within small zones, such as the viewsheds of in-aisle retail media displays and endcaps, checkout lanes, and kiosks.
BlueZoo sensors continuously listen for these BLE advertisements using standard Bluetooth radios and report these advertisements to our cloud servers for processing. By detecting and analyzing these anonymous broadcasts, BlueZoo reports impressions delivered, momentary occupancy, and visitor dwell time. Unlike Wi-Fi, for which some smartphones broadcast probes with persistent “global” MAC addresses, all BLE device addresses are randomized ensuring complete user privacy.
Like all BlueZoo technologies, BLE detection is both passive and privacy-first. No mobile application, pairing, or user interaction is required, allowing organizations to collect reliable audience analytics while respecting consumer privacy. BLE detection is available alongside passive Wi-Fi on the same BlueZoo platform, giving customers the flexibility to choose the right measurement technology—or combine both—to match the requirements of each deployment.
BLE is best suited for:
- Measuring short dwell times with higher temporal precision,
- Counting fast-moving audiences of signage with small viewsheds (e.g. in-aisle) with high precision,
- Environments where aggregate counts of impressions are satisfactory and the unit share of iPhone is substantial (because BLE only detects iPhones)
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