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Bluetooth 5 is bold. It’s trending. And it’s triggered a new wave of excitement for Bluetooth developers because of the plethora of devices that can be controlled from devices like smartphones (see figure). Now that we’ve watched the confetti fall from this big launch, let’s sift through the details to debunk the biggest myths of Bluetooth 5.
1. Bluetooth 5 isn’t backwards-compatible with legacy Bluetooth devices.
The beauty of Bluetooth 5 is that it’s completely backwards-compatible with Bluetooth 4.0, 4.1, and 4.2 devices. Another added benefit is that you can apply all of the features of legacy Bluetooth core specifications to Bluetooth 5. For example, you can use the data-length extensions from Bluetooth 4.2 in conjunction with the high speed of Bluetooth 5 to leverage an optimal feature set for your design.
2. Bluetooth 5 has higher speed and longer range.
One of the biggest misnomers about Bluetooth 5 is the idea that users can operate at 2 Mb/s with extended range, which isn’t the case. The high-speed and long-range features are at opposite ends of a spectrum: You must choose whether data rate or range is most important, because a device can’t operate in both modes at the same time. For instance, to achieve maximum range, you must sacrifice the data rate, which drops to 125 kb/s.
3. Bluetooth 5 long range is achieved by increasing the output power of the radio.
A big advantage of long-range modes is that there’s no increase in power consumption. By using coded physical layers (PHYs), receiver sensitivity improves while maintaining the same transmit (TX) and receive (RX) current as Bluetooth 4.0, 4.1, and 4.2. Bluetooth 5 uses forward error correction (FEC) to expand the payload data bits 1-to-2 or 1-to-4 at data rates of 500 kb/s or 125 kb/s, respectively. The receiver can now more readily distinguish between a signal and noise.
4. Bluetooth 5 includes Bluetooth Low Energy (BLE) mesh.
Countless Bluetooth developers were eagerly awaiting the ratification of BLE mesh with Bluetooth 5. To the surprise of many, BLE mesh was released independently, and after the announcement of Bluetooth 5. This is a subtle but important fact –BLE mesh is outside the core Bluetooth specification. This means that you can use mesh in conjunction with Bluetooth 4.0, 4.1, 4.2, or 5.
5. Bluetooth 5 improves coexistence with Wi-Fi devices.
Bluetooth 5 was marketed as improving wireless coexistence and interoperability, a statement that can easily be misunderstood as enhanced coexistence with a Wi-Fi device. The real improvement in coexistence is with other nearby BLE devices. The random frequency-hopping scheme of Bluetooth 5 decreases the chance of a neighboring BLE device transmitting on the same radio-frequency (RF) channel at the same time, thus increasing the overall robustness of each connection.
Bluetooth 5 allows a user to control many devices from Bluetooth-equipped smartphones and other devices.
6. In high-speed mode, the time between packets is faster.
Another misconception of Bluetooth 5 is that the high speed is in terms of the speed between packets. In reality, the speed is in terms of link speed. Historically, BLE was capped at a 1-Mb/s data rate; that’s doubled to 2 Mb/s with Bluetooth 5. This means that it takes half the time to transmit data packets while maintaining the same time interval between packets.
7. A 2-Mb/s connection has the same range as 1 Mb/s.
When operating at 2 Mb/s with Bluetooth 5, there’s a loss in sensitivity when compared to 1 Mb/s. The higher data rate yields a shorter range than 1 Mb/s. But the slight range loss is also counteracted by improved radio architectures since the launch of the first BLE devices. Compared to a Bluetooth 4.0 radio, a Bluetooth 5 radio at 2 Mb/s will see a big advantage in application throughput when placed the same distance apart.
8. Bluetooth 5 devices can directly connect in 2-Mb/s mode.
This is false. Two Bluetooth 5 devices must first establish a connection at 1 Mb/s and then can switch to 2-Mb/s mode. This negotiation tactic between devices is similar to the Bluetooth 4.2 data-length extension feature mentioned earlier. The feature negotiation gives you the flexibility to dynamically change data rates based on your application needs and ensures interoperability with BLE devices that don’t support the high-speed feature.
9. A Bluetooth 5 long-range connection must be established at short range.
What a significant limitation this would be if it were true! Fortunately, with the Bluetooth 5 specification, a device can initiate and connect at long range through advertising extension. Offloading the advertising channels and using the data channels establishes a more efficient connection at long range and enables substantial application benefits where coverage is critical.
10. A long-range device can communicate with a smartphone that doesn’t support Bluetooth 5.
Here’s another crucial myth to expose. To harness the features of Bluetooth 5’s high speed and long range, both the central and the peripheral must have Bluetooth 5 support. To illustrate, for a sensor node to communicate with a smartphone at long range, the smartphone and the sensor node must support Bluetooth 5 coded PHYs.
11. BLE is only for body-area network applications.
Saving the biggest topic for last, let’s demystify the limit on BLE applications. After conception, BLE quickly picked up a stereotype as a personal-area-network technology with an application emphasis on wearables and fitness trackers. With the formation of Bluetooth 5, these barriers are breaking as the technology extends to retail, home, factory, and automotive applications. The expectation of only single-room coverage is rapidly changing; whole-home connections are now possible.
Bluetooth 5 is furthering the expansion of connected things, places, and vehicles. From industrial sensors to remote keyless entry for cars, BLE is infiltrating new and innovate spaces. Now that I’ve set the record straight, imagine where Bluetooth 5 will take developers next.
