Short Range Wireless
Dispelling the ‘short-range’ Bluetooth myth
Martin Woolley, technical program manager, Bluetooth SIG, talks about how Bluetooth could be used in the home automation sector
Martin Woolley T
he home automation sector has seen frenzied activity over the past few years. Just six years ago, there was a global installed base of only four million smart home devices. Today, the installed base is estimated by IHS Markit to be around 165 million devices worldwide, as many organisations and industry bodies have made their moves to exert their influence over this burgeoning market. But as the industry yearns for a single unified network or protocol to ‘crack’ the smart home, the truth is that the sheer number of uses cases means that there won’t be one standard to rule them all.
That being said, technologies such as Bluetooth and Wi-Fi are so pervasive and the install base so massive that it becomes a bit of a no-brainer for chip developers to focus their efforts on creating smart home platforms that build on these technologies. 2.4 GHz Wi-Fi is well suited for high bandwidth applications. It offers excellent range and network capacity for many single-location smart home applications, as well as the opportunity for strong security (if implemented appropriately). However, Wi-Fi’s cost, power utilisation and issues with coexistence (with other 2.4GHz radios and interference) may put this technology out of the running for wireless technology of choice for smart home implementations. While Bluetooth operates in the same 2.4 GHz band as Wi-Fi, it uses a feature called ‘adaptive frequency-hopping’ which helps reduce the impact of congestion from other frequencies in the radio environment. For non-streaming applications, Bluetooth offers unmatched advantages in cost, size and energy use. This makes Bluetooth perfect for devices that have constrained power sources and/or are installed in physically difficult to access locations. And as a single global standard it enables a wide range of devices from different manufacturers to communicate, no matter where they’re installed. All the major smartphone, tablet, and laptop and desktop computing platforms support Bluetooth low energy,
establishing a viable ecosystem for nearly any connected device. For smart home chip developers, that eases many connectivity concerns, as consumers can use their smartphone apps to control multiple Bluetooth devices anywhere and anytime, offering services and data to other Bluetooth devices and connection points, including the cloud.
One of the myths
surrounding Bluetooth however, is the perception that it is an exclusively ‘short- range’ wireless technology, which for some smart home developers working on solutions that aim to achieve whole home coverage, may result in hesitation. In actual fact, ‘Classic Bluetooth’ (i.e. when Bluetooth is being used for devices that need a maintained and often high- throughput connection, for example in audio streaming) has been implemented in motorcycle headsets so that it has a range of over a mile. However, due to a modified modulation scheme, the low energy feature of Bluetooth, as featured as part of the Bluetooth 4.0, 4.1 and 4.2 specifications, has a better link budget compared to Classic Bluetooth. This means a low energy Bluetooth module can offer a range in the many hundreds of metres when in line of sight. Although sensors and actuators in the home generally only need a range in the tens of metres, it is important in the aspects of robustness and reliability to have a large reserve in order to bridge temporary obstacles and interference. And Bluetooth 5, set to land at the end of 2016, is primed to increase the maximum range even further. Bluetooth 5 will introduce not only quadruple the range, but also increased speed and broadcast messaging capacity. Most importantly for smart home developers, extending the range will deliver the robust IoT connections that will make home and building automation all the more reliable. The low energy data throughput transmission of Bluetooth in its current form is 1 Mb/s. Bluetooth 5 is set to double this to 2 Mb/s. Practically speaking, this increase will reduce latency and increase responsiveness in home sensors. It will also make the technology’s performance to power consumption ratio even more impressive, especially when compared with competing technologies such as 802.15.4 (which is limited to 250Kbps) or Wi-Fi (which requires higher power consumption).
28 November 2016 Components in Electronics
It is worth noting that the distances the Bluetooth SIG provides are approximate, since discussing absolute range is contingent on a large amount of variables. It is dependent on Bluetooth chipsets, antenna design and, as is the case with all wireless technologies, the amount of background electromagnetic ‘noise’ in the environment. Right now, even before the launch of the Bluetooth 5 specification, there are commercially available modules which use the low energy features of Bluetooth and which have a range of 400 metres. With Bluetooth 5 set to quadruple this range, this will enable far more possibilities for whole home coverage with Bluetooth sensors and devices. Users will be able to place Bluetooth sensors anywhere in their home, even in the most hard-to-reach places, all of which would be able to connect back to a sensor hub. It also makes Bluetooth even more viable for use in commercial and industrial environments, whether that is for enhanced beacon deployments in shopping centres or smart lighting implementations in large office blocks.
Range, combined with the ubiquity of the technology in mobile devices, makes Bluetooth perfect for a huge variety of IoT applications in both home and wider network deployments. Stay tuned for more specific technical details from the Bluetooth SIG when the Bluetooth 5 specification officially launches at the end of the year.
www.bluetooth.com www.cieonline.co.uk
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