How to Maximize Bluetooth® Interoperability Between IoT Devices and Smartphones？

Bluetooth^® interoperability is an essential quality of an IoT device. There are thousands of smartphone models in the field with various combinations of operating systems, software, and hardware. Whichever combination your customer has, the Bluetooth stack on your IoT device must connect with it smoothly to meet and even exceed user expectations. However, testing Bluetooth interoperability against thousands of smartphone models is time-consuming and expensive. This post explains how to maximize Bluetooth interoperability on an IoT device.

Why Does Bluetooth Interoperability Matter?

Imagine the excitement when your new customer is eagerly unboxing your IoT device, switches it on, downloading the smartphone app, and connects Bluetooth. But then something goes wrong. The smartphone is searching…, searching…, searching…. and it cannot establish a connection to the IoT device.

A smartphone app is an inseparable component (e.g., the user interface) of a modern IoT device. If Bluetooth connectivity between the app and device doesn’t work, the entire product doesn't either. That's why Bluetooth interoperability is so critical in many IoT applications.

Bluetooth Interoperability Challenge

Why is Bluetooth interoperability between IoT devices and smartphones a challenge for device makers? There are thousands of smartphone models out in the market with various operating systems, firmware, and hardware variants. The number of variables grows further when all the possible applications are factored in the interoperability equation.

Whichever combination of software and hardware your customers have on their smartphones, the Bluetooth stack on your IoT device must be fully compatible and able to connect with the smartphones to meet user expectations – regardless of whether you provide wireless medical devices for consumers, smart HVAC solutions for enterprises, or access control devices for commercial.

Benefits of Bluetooth Interoperability

Smooth Bluetooth interoperability is an essential quality of an IoT device. Quick pairing, reliable connectivity, and high throughput are fundamental components of the IoT user experience. On the other hand, interoperability issues are hard to debug, which increases problem resolution time and maintenance costs. Whether consumers, enterprises, or utilities, the users want wireless that works and devices that can talk to other devices. Better interoperability improves customer satisfaction and reduces customer care calls and product returns, translating to lower risks and costs, and increased revenue.

Bluetooth Interoperability vs. Standardization and Qualification

Bluetooth interoperability is a function of all the layers of the protocol and application. An application uses the protocol to address the use case, so there are many ways of building the application.

Bluetooth SIG, the Bluetooth standardization organization, maximizes the interoperability across the protocol layers by developing and managing the standard and establishing a rigorous qualification process. However, standardization and qualification testing alone cannot ensure full Bluetooth interoperability considering the rapidly evolving and fragmenting smartphone and application space.

Testing Bluetooth Interoperability

While the benefits of interoperability are clear, so are the challenges. How can it be tested with such an extensive smartphone base and so many use cases? Moreover, not every device can be tested against every phone for all use cases.

This is where breaking up the problem into smaller pieces helps. The Bluetooth Low Energy protocol comprises building blocks such as pairing using various security methods, data transfer, and manipulating characteristics in the GATT database. Testing these building blocks with an application gives IoT device makers extra confidence – their application will be interoperable when complete.

SILICON LABS'Bluetooth Low Energy hardware and software products undergo extensive Bluetooth interoperability testing in addition to the Bluetooth SIG's qualification tests. The extra testing reduces development and maintenance costs for IoT device makers and application developers while giving your products a clear user experience and reliability advantage in the markets.

Here is a brief overview of how Silicon Labs runs Bluetooth interoperability testing. 

Test Setup

Bluetooth interoperability testing is performed in a regular office environment with Silicon Labs hardware and embedded software. This setup works well mirroring a home environment too. A Wi-Fi access point is approximately five meters away, with 15 randomly placed devices generating interference on the 2.4 GHz spectrum. The device under test (DUT) is placed one meter away from the smartphones.

Fig.1

Test Cases

The Silicon Labs test team runs numerous interoperability test cases against smartphones in the following categories: Bluetooth LE scanning, Bluetooth LE connection, GATT operations, characteristics, OTA update, throughput, security, and encryption.

Smartphone Coverage 

The most recent testing was conducted with 17 iOS devices and 77 Android devices with different Bluetooth qualification IDs. All smartphone models sharing a Bluetooth qualification ID share an identical Bluetooth design, functional behavior, and interoperability characteristics. As a result, testing against these 94 device models effectively ensures a high level of confidence for Bluetooth Low Energy interoperability with 2,256 different smartphone models. The device models (i.e., qualification IDs) were chosen to maximize smartphone interoperability for your Bluetooth-enabled IoT devices with Silicon Labs!

Bluetooth Interoperability Test Results

See Silicon Labs'application notes for the complete test reports on Bluetooth Low Energy.

How Can You Test Bluetooth Interoperability Easily?

If you want to test Bluetooth interoperability, Silicon Labs provides a smartphone app, EFR Connect, allowing you to test mobile interoperability quickly.