How Far Can a Bluetooth Beacon Measure Distance?

A common misconception is that beacons can measure distance. In reality, beacons, with the exception of some specialist social distancing beacons and sensor beacons with an additional distance sensor, are designed to send signals rather than receive them.

Instead, measuring distance happens on the receiving end. Devices such as smartphones are equipped to detect these beacon signals. When a beacon sends out its Bluetooth radio signal, the receiving device knows the received signal strength (RSSI). This RSSI can be used to infer the distance between the beacon and the device.

In the proximity of a few metres, the variation in RSSI is significant enough to deduce the distance with a reasonable degree of accuracy. However, as the distance increases, the variation in RSSI becomes less pronounced. This means that while you can determine if a beacon is close or far away, pinpointing an exact distance becomes challenging.

For example, the iOS programming API, CoreBluetooth, provides classifications for the detected beacon signals. These classifications are ‘immediate’, ‘near’, and ‘far’. They don’t give a precise measurement in metres or feet but rather a general idea of the beacon’s proximity.

In terms of maximum range, depending on the specific beacon, it can be detected from distances up to 50m or even 100m. However, as mentioned earlier, at these longer ranges, the RSSI doesn’t provide a clear indication of exact distance. Instead, it offers a more general sense of whether the beacon is nearer or farther away.

Location System Anchor Optimisation

Researchers from Department of Computer Science, University of Jaén, Spain have a new paper on OBLEA: A New Methodology to Optimise Bluetooth Low Energy Anchors in Multi-occupancy Location Systems.

This paper introduces a new methodology called OBLEA, which aims to optimise BLE anchor configurations in indoor settings. It takes into account various BLE variables to enhance flexibility and applicability to different environments. The method uses a data-driven approach, aiming to obtain the best configuration with as few anchors as possible.

The OBLEA method offers a flexible framework for indoor spaces where the occupants are fitted with wrist activity bracelets (beacons) and BLE anchors are set up. The anchors then collect and aggregate data, sending it to a central point (fog node) via MQTT.

A dataset was generated with the maximum number of anchors in the indoor environment, and different configurations were then trained and tested based on this dataset. The best balance between fewer anchors and high accuracy was chosen as the optimal configuration.

This methodology was tested and optimised in a real-world scenario, in a Spanish nursing home in Alcaudete, Jaén. The experiment involved seven inhabitants in four shared double rooms. As a result of this optimisation, the inhabitants could be located in real time with an accuracy of 99.82%, using a method called the K-Nearest-Neighbour algorithm and collating the signal strength (RSSIs) in 30-second time windows.

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What is the Difference Between iBeacon and Eddystone?

iBeacon, a standard developed by Apple, was introduced in 2013 as part of the iOS 7. It’s based on Bluetooth Low Energy (BLE), a power-efficient variant of Bluetooth technology. The strength of iBeacon lies in its background support on iOS devices, which allows for easier detection of beacons.

Google introduced Eddystone in 2015. This protocol for beacons was developed to embrace a broader range of uses. Eddystone offers multiple frame types to cater to various data needs like URLs, unique identifiers and sensor data. One most distinctive feature of Eddystone was the Eddystone-URL, where the beacons could send out a web address. However, this has been limited by the discontinuation of Google Nearby in Android.

Despite the differences in their design and features, both iBeacon and Eddystone share common ground in their use of standard Bluetooth advertising. They send different data in the same standard Bluetooth advertising packets. This shared aspect of technology ensures that they can both communicate effectively to both iOS and Android.

While Eddystone’s versatile frame types and open protocol initially made it appealing, it has seen a decline since the discontinuation of Nearby in Android. Currently, most new systems requiring smartphone applications to detect a beacon opt for iBeacon.

However, when it comes to locating and detection using gateways rather than smartphones, iBeacon vs Eddystone becomes less relevant and the beacons’ Bluetooth MAC addresses are usually used. The advertising packets can instead be used for sensor data, for example, temperature and humidity.

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Monitoring Sheep Location Using Bluetooth Beacons

There’s new research from Scotland, UK on Calibration of a novel Bluetooth Low Energy (BLE) monitoring device in a sheep grazing environment. Knowing an animal’s location and proximity can offer insights into landscape use, animal performance, behaviour and social contacts. However, the technologies currently used to collect these data are costly and challenging to implement, particularly due to the low value of individual animals and typically large flock sizes.

A device was specifically designed for a study to assess the relationship between the Received Signal Strength Indicator (RSSI) of a BLE beacon and BLE reader and to develop a distance prediction model. This model was then applied in a static situation and on-sheep studies, using a multi-lateration approach to determine a beacon’s location within a field setting. A purpose-built Wearable Integrated Sensor Platform (WISP) was developed for the study, featuring a BLE reader and other sensors. It was designed to report the identity and RSSI of the 16 ‘closest’ beacons seen for each duty cycle.

The findings revealed that the height of the device had an impact, with fewer beacons reported at a shorter distance in WISPs at the lower height of 0.3 m. RSSI can vary greatly based on factors like transmission power, device orientation, enclosure and the operating environment.

Using the distance prediction and adjusted distance prediction, beacon locations could be estimated for most of the beacons. Not all beacons could be located due to issues such as being reported by too few WISPs or the resulting multi-lateration circles not intersecting.

The study suggests that BLE can potentially be used for sheep localisation in outdoor environments. The multi-lateration approach is dependent on receiving RSSI readings from multiple readers at a similar timepoint, it could offer more information about localisation and movement than simple proximity ranges or presence/absence. Locating a sheep to within about 30 m in a field environment represents a significant step forward.

Does Bluetooth Signal Go Through Walls?

One question that often comes up is whether Bluetooth signals can go through walls. The answer is a bit more nuanced than a simple yes or no.

Bluetooth operates on a 2.4 GHz ISM (Industrial, Scientific, and Medical) radio frequency band. This frequency is also shared by other wireless technologies like Wi-Fi. Bluetooth signals are designed to be robust but are generally short-range, typically extending up to 50 metres. As it uses the same frequency as Wi-Fi which most people have a knowledge of range of, a very rough approximation is to think of Bluetooth as being similar to Wi-Fi.

The material of the wall plays a significant role in how well a Bluetooth signal can pass through it. Materials like drywall, glass and wood are generally more permeable to Bluetooth signals. In contrast, concrete, brick and metal can severely limit or block the signal altogether.

The strength of the Bluetooth signal also matters. Higher-powered Bluetooth devices can transmit signals that are more likely to pass through walls. However, even with a strong signal, the quality may degrade as it passes through obstacles.

The distance between the transmitting and receiving devices will also impact the signal’s ability to pass through walls. The closer the devices are to each other, the more likely it is that the signal will successfully penetrate the wall.

In practical terms, while it’s possible for Bluetooth signals to go through walls, the quality and reliability of the connection can be compromised.

So, does Bluetooth signal go through walls? The answer is yes, but with caveats. The type of wall, the strength of the signal, interference from other devices, and the distance between the connected devices all play a role in determining how well a Bluetooth signal can penetrate walls.

Can I Set the Maximum Distance the Beacon Transmits?

Many people inquire about adjusting the transmission distance of a beacon. They often wish to either conserve battery or restrict the range at which a beacon is detectable.

While some third-party platforms and SDKs offer distance settings, it’s a misconception to think you can directly set the distance. What you’re actually adjusting is the transmission power, which in turn influences the transmission distance. But since this involves radio waves, which are prone to reflections and interference, it’s impossible to guarantee that a specific power will equate to a precise distance.

When using an app to detect beacons, you can employ the Received Signal Strength Indicator (RSSI) to focus on those within a desired range. However, it’s challenging to precisely correlate RSSI with the actual distance.

Some wonder if they can set the distance in terms of centimetres, similar to NFC. Typically, this isn’t feasible because even at their lowest power setting, most beacons transmit over a distance of about a metre.

Rather than asking if the transmitter’s distance can be minimised, it might be more practical to configure the receiver to disregard detections from further away. By using the RSSI value on the receiving app or another Bluetooth scanning device, you can filter out distant beacons. Specifically, you can dismiss detections with an RSSI below a certain threshold, allowing you to focus on detections within a centimetre range.

We have an article on Choosing the Transmitted Power.

The Limitations of Bluetooth Mesh

Earlier this year, we made the decision to retire SensorMesh™, a product that was built on top of the standard Bluetooth mesh framework. At first glance, Bluetooth mesh appeared to be a promising technology—serverless, open, adaptable and with an extended range compared to standard Bluetooth LE. However, as we got into its implementation and use, we found that the limitations outweighed the benefits.

Our SensorMesh™ was designed to be a versatile solution for various applications. It provided a new Bluetooth Mesh model that allowed the participation of any Bluetooth beacons or other devices without them requiring firmware updates. The system also allowed for payload filtering and time-based control to manage throughput. It was capable of transmitting data from a variety of sensors, such as location, movement, button press, temperature, humidity, air pressure, light level, open/closed status, and proximity, over the mesh network:


One of the first issues we encountered was the complicated provisioning and setup process. Unlike turnkey solutions, Bluetooth mesh required a provisioner, usually an app on a smartphone, to store encryption keys. This made the initial setup far from straightforward and ongoing management difficult.

Another significant limitation was the very low throughput, which was in the order of a few thousand bits (yes bits!) per second. For most applications, especially those requiring IoT data transmission, this was not sufficient. In many cases, using gateways proved to be a more effective solution.

The Bluetooth SIG’s chosen flooding architecture, while excellent for low latency, consumed too much power for battery-operated devices. As a result, we had to resort to installing firmware on USB dongle -style devices, which were permanently powered. This was inconvenient for many applications we saw from potential clients where mesh networks would have been ideal, such as in mines, hospitals, factories, farms and even battlefields where existing networks are already congested or non-existent.

We also found that Bluetooth GATT clients at the edge of the mesh, responsible for relaying the mesh data somewhere else, easily became congested despite the low throughput. Our workaround involved using USB dongle with mesh firmware and a COM port rather than GATT.

Bluetooth mesh offered no way to trade latency for less power consumption. Its throughput was too limited for most uses, a problem inherent to the technology. Since its announcement in 2017, Bluetooth mesh hasn’t seen many implementations outside the lighting industry. We believe this is because it was driven, designed and optimised for lighting scenarios, which require low latency and permanent power but can tolerate low throughput. Sadly, enhancements recently provided by Mesh 1.1, such as directed forwarding, device firmware update, remote provisioning and subnet bridging have come about mainly to solve problems found in Network Lighting Control (NLC).

In the end, we retired SensorMesh™ because it didn’t have a good product-market fit. The underlying characteristics of Bluetooth mesh were too limiting to make it a useful solution for the applications our customers envisioned. While Bluetooth mesh may have its niche uses, we believe its limitations make it currently unsuitable for broader applications.

Development of a Bluetooth LoRa Gateway Using ESP32

There’s new research on the Design and Implementation of a BLE Gateway Using ESP32 chipset (PDF). Bluetooth Low Energy (BLE) and Long Range (LoRa) are commonly used wireless technologies for IoT devices, useful for their low power use and long range respectively. The mixing of BLE and LoRa in a single gateway significantly improves the flexibility of IoT networks, providing efficient data gathering and transmission.

An affordable, flexible gateway was developed, combining the benefits of BLE and LoRa communication and taking advantage of the ESP32 microcontroller’s capabilities. This setup allows for effective data collection from BLE devices and transmits the consolidated data to an MQTT server or a LoRaWAN cloud.

An initial prototype was produced, which led to a customised solution based on a PCB.

Looking to the future, the author says there’s scope to improve the software and firmware further, optimising the algorithms, reducing power usage, and exploring additional features such as multiple communication protocol support or advanced security measures. Such advancements could offer a more adaptable and reliable solution for users’ wireless communication needs.

However, the necessity of refining this solution is questionable as there are existing solutions, such as the LW003-B LoRaWAN Probe, already available, that solve these issues and productise in a case.

Can Bluetooth Beacons Track Individual User Data?

Bluetooth beacons themselves are generally not designed to track individual user data. They are small devices that transmit a Bluetooth signal at regular intervals, which can be picked up by smartphones or other Bluetooth-enabled devices within a certain range. The primary function of a beacon is to broadcast its presence and certain identifying information such as a unique ID.

However, the apps on your smartphone that interact with these beacons could potentially collect and store data about your location or behaviour. For example, a retail store might use beacons to send promotional messages to your phone when you’re near a particular product. The app on your phone that interacts with the beacon could collect data on which promotions you’ve seen, how long you spent in a particular area of the store and other information.

While the beacon itself is not tracking you, the software that interacts with it could be. It’s essential to be aware of the permissions you’re granting to apps on your phone, particularly those that request access to your location services.

Using Bluetooth Beacons for Medical Equipment Tracking

There’s recent research from Faculty of Sciences and Technology, Bansomdejchaopraya Rajabhat University, Bangkok on Development of Prototypical Indoor Real-time Location System for Medical Equipment Management Based on BLE Devices.


The research proposes a prototype for an indoor real-time location system (RTLS) using Bluetooth Low-Energy devices for tracking medical equipment. The ESP32 microcontroller acts as a receiver node in each room, collecting the MAC address from the HM-10 beacon attached to the equipment and sending this data to a web server.

To calculate the distance between the node and the beacon, the Received Signal Strength value is filtered to reduce noise. Tests show that the average distance error between the beacon and node is roughly 3 metres and and the maximum time to update the location from node to node is less than 15 seconds.

This solution offers precise timestamps and location information based on distance, range, duration or direction.