Communicating data in the IoT – part 2
In part 1 of this article we looked at how new ultralow-power RF transceiver technologies are bringing class-leading range performance and high resilience to interference sources.
There are a number of advantages to combining the MCU and RF transceiver into a single module. Time to market is a major consideration for the fast-moving IoT. This approach is particularly attractive to design teams that don’t have RF and digital expertise in equal measure. It also simplifies integration and reduces the risk. This is especially relevant in the case of modules that are pre-certified to specific wireless protocols.
LoRa and Sigfox are the current leading contenders in the industrial IoT for long range connectivity, and connectivity modules are available for both standards. For example, Analog Devices will have a Sigfox-certified device, whilst STMicro favours LoRa, says Paul Dawson, divisional marketing manager, Analog Devices Anglia Components.
Both standards use unlicensed ISM bands and are based on star topology. Sigfox uses ultra-narrowband technology, giving it higher spectral efficiency than LoRa’s chirp spread spectrum – hence better resilience to noise. Sigfox has better range so each base station can connect many more devices. Sigfox excels for infrequent transmissions and offers longer battery life, whilst LoRa uses more bandwidth.
Such technical issues are not so significant as the differences in business model between these rivals. LoRa is owned by Semtech and requires vendors to use Semtech modules for their development. Conversely, Sigfox shares its reference design with IC vendors, so devices with Sigfox certification can use its infrastructure.
LoRa networks are dominant in Europe, with future expansion dependent on its alliance community. Meanwhile Sigfox is rolling out its network in 100 US cities, as well as in Australia, New Zealand, Brazil and the Middle East.
Thread is arguably the leading protocol for domestic IoT communication, designed specifically for Connected Home applications including smart thermostats like Nest and voice command devices such as the Amazon Echo. The protocol uses IPv6-based networking and a variety of application layers can be used on the stack. Simple protocols for forming, joining, and maintaining Thread Networks allow IoT ‘things’ to self-configure and fix routing problems as they occur. It focuses on security, as devices cannot join the Thread network unless authorised and all communications are encrypted.
The network layer is designed to optimise the network operation based on its domestic setting. Spread spectrum technology is used at the physical layer to provide good immunity to interference. In contrast with industrial solutions, typical host devices can operate for several years on domestic AA type batteries.
Communications protocols like these look set to become more important as traditional GSM communication networks decline in favour of high-speed LTE. Nevertheless, lower data rate versions such as CAT1, CAT-M and NB-IoT could be the ideal complement to more-intelligent IoT nodes.
Open tools speed development
For developers, new open tools and embedded OS solutions will make support for these varying standards less onerous. The mbed ARM offering would appear to be gaining the most traction with all major silicon suppliers involved and basic connectivity already supported.
The mbed platform helps developers create their own embedded connected devices, from planning, through prototyping to production. Software is written on top of an operating system, mbed OS, that works with mbed-enabled hardware, and can connect to the cloud using the mbed Device Connector Service.
Designs that already have an operating system can use the mbed Client to access higher-level cloud connectivity functions of mbed OS. In this way, developers can use existing services without having to use mbed OS or mbed-enabled hardware.
ARM’s in-house operating system – mbed OS – offers a simple and consistent method of controlling the hardware and interacting with the cloud. It also offers built-in integration with tools such as debugging and automated test.
From hardware, through data communication protocols, to design and development tools, it’s getting easier, less costly and more secure to communicate data in the Internet of Things.
The author of this blog is Paul Dawson, divisional marketing manager, Analog Devices Anglia Components
About the Author:
Paul Dawson is divisional marketing manager at Anglia for Analog Devices and has been with the company for over four years. He has nearly twenty years’ experience of electronic design, including as chief engineer at AD Aerospace and as a senior applications engineer at Fujitsu Microelectronics Network Products Division. He has an honours degree in Electrical and Electronic Engineering.
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