Bluetooth Low Energy Is Everywhere—and Now BLE Is Teaming Up with Other Wireless Protocols

Where Is BLE Technology Making the Most Impact?

The Bluetooth standard as a whole is enjoying a healthy growth rate, with annual shipments of 7.6 billion units by 2027, according to ABI Research and the Bluetooth Special Interest Group (SIG). Platform-type devices such as PCs, tablets, and cell phones tend to deploy dual-mode Bluetooth (Classic plus BLE), though their growth rate is fairly flat. What’s driving most of the growth is the peripheral device side, where battery-powered devices that benefit from BLE-only solutions dominate. BLE operates in the 2.4GHz unlicensed radio band, providing wireless connectivity to devices nearby. Over the next few years, BLE-only shipments are expected to triple.

Use cases can be grouped into four key segments, according to ABI Research and Bluetooth SIG:

• Audio streaming includes wireless speakers, headsets, and earbuds, as well as in-car systems, such as hands-free infotainment. Bluetooth SIG’s Auracast broadcast audio capability enables a smartphone, tablet, TV, or other audio source device to broadcast an audio stream to an unlimited number of audio sink devices, such as earbuds and speakers. This opens up new possibilities, such as enabling moviegoers to select a preferred language at the theater or being able to tune into a particular TV in a public venue like a gym or a sports bar.
• Data transfer involves syncing devices such as wearables and PC peripherals with apps or host systems. Fitness trackers, smart watches, keyboards, and trackballs fall into this segment, as do health and wellness devices such as remote heart rate and blood pressure monitoring tools. Another area pertaining to data transfer is device provisioning and access for other wireless devices, such as switches, door locks, and utility meters.
• Location services is one of the fastest growing segments, covering asset tracking, indoor navigation, and positioning. Examples include real-time location services (RTLS) such as those used for work-site tools, medical devices, or even with hospital patients; visitor navigation systems used in airports, museums, and stadiums; digital keys for secure entry into cars, homes, and buildings via cell phones; and personal asset tracking tags for keys, wallets, etc.
• Device networks is another segment that is poised for healthy growth in the coming years. Examples include control system mesh networks for lighting, commercial building automation, and smart homes; monitoring systems for factory control, HVAC equipment, and parameters such as lighting, temperature, vibration, occupancy, and humidity; electronic shelf labels that enable dynamic pricing; and automotive applications like electric vehicle battery monitors and tire pressure monitors. 

Why Multi-Protocol Wireless Solutions Are Trending

From the use cases covered, we can see that Bluetooth and particularly BLE are thriving as stand-alone wireless protocols. We are now seeing more instances of BLE being used as a complimentary wireless technology with other wireless protocols to enable access, control, and provisioning/commissioning applications. Let’s take a closer look at some key wireless protocols that can be paired with BLE.

• Zigbee Direct uses BLE to simplify network on-boarding by setting up nodes on Zigbee-based mesh networks. For the past 20 years, Zigbee has been seen as a competing low-power, short-range technology to Bluetooth. Zigbee Direct reduces complexity because it doesn’t require cloud access or hubs for device on-boarding and maintenance of large commercial applications and smart home networks. Combined with BLE, it is ideal for residential, commercial, and utility/energy applications.
• Thread has defined a methodology for BLE commissioning via the use of a Thread/Bluetooth dual-mode device within the Thread mesh network. This requires a certificate-based authentication over a direct link transport security layer (TSL) connection, which provides a level of security. More robust and secure BLE commissioning methods have been added to the original specification, which was defined in 2019.
• WiFi is proving to be a popular dual-protocol solution with BLE. Since these two protocols operate as separate radio systems on an SoC, they use packet traffic arbitration to coordinate the use of the airways so they can co-exist. Examples of these combo chipsets in action include BLE access to hotel room locks and BLE provisioning for smart switches.
• Ultra Wide Band, or UWB, has emerged as a complimentary wireless technology for very accurate distance measurements. Before UWB came into the picture, BLE had been used in vehicle key fobs and even phones for accessing and, in some cases, starting cars. Now, UWB and BLE interact via a hand-off approach depending on range, application, and security level.
• Wireless wide area network (WWAN) with BLE is being used for commissioning, particularly in smart city applications. One of the most prominent examples of this is smart metering for electricity, water, and gas. There are a range of WWAN protocols in use based on regional and/or utility company preferences. During installation, all the protocols must be on-boarded or commissioned onto the network of choice. However, there’s no access port in the enclosed, water-tight meter to allow this. This is where BLE comes in—adding the protocol to the main MCU on the motherboard provides wireless set-up, commissioning, and maintenance functions. 

Emerging BLE Applications on the Horizon

As rich as the BLE landscape already is, there’s a number of emerging applications that should be exciting to watch. The automotive space, for instance, offers great potential. With the rise of decentralized zonal architectures in cars, BLE can be used as cable replacements, reducing weight and improving reliability. Electric vehicle battery monitoring systems is a rapidly growing BLE application. Again replacing cables, BLE can enable charging as well as control of individual battery cells for maximum performance, safety, and cell lifetime management. In tire monitoring systems, BLE could become the standard, replacing proprietary wireless protocols. With the addition of MEMS sensors, tire monitoring systems can potentially provide not only tire pressure data but also monitoring of temperature and vibration as well as predictions on tire tread. BLE is starting to support applications for engine and system diagnostics and maintenance and be used in production assembly facilities.

Hearables—including over-the-ear, on-ear, and in-ear devices—are another market segment that benefits from the low power consumption of audio over BLE, also referred to as LE Audio. Bluetooth SIG’s Auracast is anticipated to spark a major inflection point for hearables. Currently, wireless speakers and over-the-ear devices primarily use dual-mode Bluetooth. However, considering the limited battery life of smaller in-ear devices—think hearing aids and ear buds—BLE-only audio solutions are expected to take hold here before migrating over time to larger devices like over-the-ear headphones.

Electronic Shelf Labels (ESLs) present a very interesting and growing application for BLE. Somewhat driven by supply chain issues seen during the COVID-19 pandemic and compounded by recent inflation, price changes on products can be an almost daily exercise. Compared to the manual process to change prices on paper labels, ESLs make fast and easy work of these updates. Powered by coin-cell batteries, ESL devices are expected to last several years before the batteries need to be changed. This can only happen if the electronic labels are mostly off, waking to check for periodic pricing changes. BLE, with its new “Periodic Advertising with Responses” (PAwR) feature, supports this mode of operation, allowing bi-directional, energy-efficient communication to thousands of end nodes. 

What’s Next for Bluetooth Low Energy?

Various working groups in the Bluetooth community continue to define and develop new BLE features that can open the door to new functionalities. Some of the most promising features include: channel sounding or High-Accuracy Distance Measurement (HADM) to support locating systems that provide even higher levels of accuracy/positioning. Additional future BLE specifications will support higher data throughput, up to 8Mbps as well as operation in higher frequency bands (5-6GHz).

Regardless of whether BLE is used alone or in conjunction with other wireless protocols, wireless SoC designs need to be optimized for unique PPA requirements. Many of the end applications are power- and space-constrained, which is why BLE is a great fit. However, the chips need to meet these demands as well, and this is where wireless IP plays an important role. While you can design your own IP, this takes expertise and time (which equates to cost and risk). Most silicon vendors these days already license several IP blocks to build their SoC. BLE can just as easily be a part of this mix.