Bluetooth beacons enable proximity-based, contextual awareness using simply a smartphone with applications. Wireless proximity detection technology is not new, but with Bluetooth Low Energy's features, beacons can be designed for retail customers, business loyalty programs, industrial asset monitoring, and more.
Beacon Basics
In general terms, a beacon is a small, battery-powered, wireless device that uses Bluetooth low energy technology (Bluetooth Smart) to advertise its presence and services. It does this by repeatedly broadcasting or advertising a beacon identifier to compatible smartphones or tablets within its proximity. The smartphone or tablet can then use the beacon’s information to determine its location and services. By monitoring beacons, a device can detect when it has entered or exited a particular area, and then use that information to create interactive experiences based on what’s nearby.
Beacons are typically used in one of two scenarios. The first and most common is for a beacon to be placed either in a fixed location or on a movable object, then relying on a smartphone to correlate beacon proximity to a desired behavior such as opening an app or offering contextually-relevant content.
The second uses a fixed wireless node to monitor beacons on objects that pass by or through its monitoring area. It then can report back to another application using a wired or wide-area network. This model might apply to asset tracking for expensive tools and equipment, livestock, or even people (wearing a bracelet tag for example).
The two usage scenarios above rely on proximity awareness. In the first scenario, a user's smartphone comes into proximity with a beacon. In the second, beacons come into proximity with a beacon-monitoring node. Both models are finding applications in retail and commercial businesses.The most established applications focus on retail shopping. Beacons distributed throughout a store allow loyalty apps to offer personalized experiences to its customers. The applications serve tailored messages and coupons and track the customer’s reactions for additional customization.
Commercial beaconing applications are also being designed and deployed. As mentioned above, beacons can track and help manage important assets like expensive power tools. A beacon-enabled tool allows it to “check in” to a monitoring node to determine when it is in a tool bin, on the shop floor, or not in range. The same beacon application can monitor and report tool status such as charge level, operating time, and performance. This has obvious implications to the lifetime and security of the tool as well as its optimized utilization.
Designing a Bluetooth Beacon
Although a beacon can be relatively simple, the designer will need to take into consideration the hardware and software building blocks, trade-offs with battery life, how the beacon will be provisioned or deployed into the field, security and privacy, etc. Here's a quick overview:
- Hardware Building Blocks: In its most basic form, a beacon can be implemented with a wireless System-on-Chip (SoC) or a module, along with a battery and a mechanical enclosure. More typically a beacon will include other components that provide functional user interaction such as pushbuttons, LEDs, piezo buzzers, and/or reed switches. If a beacon is embedded into a product with other features, it might include additional sensors such as temperature, light or hall-effect sensors, which can interface directly to the wireless SoC. A pre-certified module provides the fastest time to market, avoiding significant up-front engineering investments and RF compliance testing, while a discrete SoC design might provide size or cost savings.
- Software: It’s fundamentally important to choose a widely deployed and field-proven Bluetooth stack. Most often, this market success is more important than any promises of new cutting edge features. Market success indicates good customer support and a stable stack, both of which help get to market quickly. For beacons in particular, it’s very important that the protocol efficiently manages sleep modes. When a beacon broadcasts on 100 ms intervals, it only transmits for about 1 ms and sleeps for the other 99; thus spending 99% of its life in sleep mode. Some proven protocol stacks include special features designed specifically to make Bluetooth and beacons more power efficient. One example is the ability to define multiple beacon frame types (iBeacon, Eddystone-URL, etc.) along with their timing parameters which the stack can then interleave autonomously without the more power-hungry application code running. Other important software features include watchdog timers as a fail-safe mechanism, real-time clocks to set beacon on/off cycles to preserve power, and the ability to support firmware updates.
- Application Code: Beacon application code can be relatively simple and implemented with a high level programming language like BGScript
from Silicon Labs. BGScript is a simple, high-level, BASIC-like programming language that’s human readable and allows Silicon Labs devices to run standalone without an external processor. The benefit of this type of high-level programming language is that the developer can focus on the application itself without concerning himself/herself with the timing and complexities of the protocol stack underneath.
- Battery Life: As with any product, the size of the battery versus its power consumption will determine its operating life. Battery size is sometimes dictated by the beacon industrial design, so a compromise must be made between battery life and the physical constraints of the final product.The beacon’s transmit power and beaconing interval also play an important role in battery life. These parameters are typically trade-offs against the desired range and proximity accuracy. Higher transmit power provides longer range and a wider coverage area, but the transmitter will draw more power from the battery for each beacon event. The application usage model needs to be considered: Will the application benefit from a larger coverage area? Or is it better to have its proximity limited to a few square meters? Likewise, the beaconing interval is an important factor in determining a beacon’s battery life. A beacon’s power consumption peaks at several milli-amps while transmitting. Otherwise, it only draws micro-amps while in deep sleep. In terms of performance, a shorter beaconing interval means there are more beacon events to capture, providing more motion resolution and therefore better location accuracy. A longer interval means the beacon will have longer battery life but fewer opportunities to get captured, especially by a moving smartphone.
- Privacy and Security Issues: Typically, beacons do not collect data since they are one-way devices—they only broadcast.They do however, provide the ability for a smartphone to know when it’s near a known beacon, and in some cases (if the beacon is stationary), the smartphone might have access to information about the location of that beacon. The smartphone translates this information to provide location and usage-based services, either through an app or in the case of the Physical Web, with contextually-relevant search results. It’s important to note that the same smartphone can provide the same services based on GPS, Wi-Fi, or cell towers, so beacons are not exposing new concerns, just making them more widespread through their success. In all cases, smartphone users can simply enable or disable proximity services in their settings. Similarly, concerns have been raised about beacons creating added security risks for IT systems. But this again implies capabilities that most beacons do not have. The typical beacon is a standalone device with no connection to any other network, wired or wireless.However, some beacons are designed with infrastructure network access which allows for central management of a beacon fleet. In these cases, the beacon manufacturer provides the same level of tamper security as they would for any other device attached to their IT network. On the beaconing side, the beacon’s data is, by design, broadcast for all to hear so does not necessarily need to be encrypted or protected in any way. In beaconing applications where proximity to the beacon may have tangible value, such as reward points for example, the beacon OEM will implement additional safeguards against beacon spoofing. Without them, spoofed beacons might fool the system into crediting events too often or to the wrong person. The safeguards could include simple timestamps for each proximity event with a test for an improbable or unanticipated frequency, the use of ephemeral IDs, or the use of randomized security keys, generated with each proximity event and validated by the back-end system.
To learn more about Designing Bluetooth Beacons, please download the attached document by Silicon Labs called "Developing Beacons with Bluetooth
Low Energy (BLE) Technology," which was the source of information for this document.