Wireless connectivity is ubiquitous; an invisible technology that has changed the networking infrastructure and is now enabling the IoT. The implementation of wireless data communications is achieved on many levels, and in its simplest form can exist purely as a link between two devices communicating over a short range, without the need for any kind of protocol. Increasingly, of course, applications require a more sophisticated solution that supports some form of networking between multiple devices and, here, the landscape is very different; one dominated by standards.
The proliferation of wireless communications is largely thanks to the openness of the RF spectrum. The vast majority of standard-based and proprietary protocols operate in the license-free part of the spectrum which, while open to anyone, still comes with strict restrictions in terms of operating power. Because of this, implementing a wireless connection is easiest to achieve using either technology designed to comply with an industry standard, or proprietary technology that has already been approved for use by the appropriate governing bodies.
Increasingly, it is the ability to create networks of devices that is propelling the popularity of industry standards, but in broad strokes the different technologies available can be categorised by range and bandwidth; both of which influence the operating power which is becoming an increasingly important design parameter.
Choosing a protocol
There are many protocols used in the licence-free ISM (Industrial, Scientific and Medical) and SRD (Short Range Device) frequency bands, both Sub-1 GHz and 2.4GHz. Some standards-based protocols such as Zigbee operate in both bands but for historic reasons proprietary protocols are more likely to operate in the Sub-1 GHz band. Semiconductor providers such as Texas Instruments offer a wide range of solutions for wireless connectivity, from transducers to fully-integrated wireless microcontrollers (MCUs); the SimpleLink MCU Platform now supports over ten wired and wireless protocols, ensuring there is a solution to fit every application.
Know your area
Although the concept of range still exists as the maximum distance between two devices over which a reliable wireless connection can be sustained, the advent of mesh networking has rendered its relevance somewhat moot. A network of many devices connected using a short-range wireless standard can theoretically span an area many times greater than the range of one point-to-point connection. The latest version of Bluetooth, Bluetooth 5, now supports mesh networking and so, in principle, has the ability to create a single network of devices with unlimited range. However, Bluetooth has its foundations in Personal Area Networking; short-range communications between small devices with relatively low bandwidth demands.
While there may be no ‘wrong’ choice when selecting a wireless technology, there are still excellent reasons for choosing a particular standard for a specific application area. Range may be less crucial but bandwidth is still a major consideration, primarily because the amount of data sent/received still has a direct impact on both the power required and the complexity involved. Fortunately there is a growing number of highly-integrated solutions that successfully address both of these design challenges.
The IoT will see many devices with low bandwidth requirements, such as smart sensors, home appliances and entertainment systems, industrial control and monitoring, as well as emerging applications within the home, office and car. For applications with higher bandwidth requirements, Bluetooth becomes more relevant. As bandwidth requirements or network complexity increase further, Wi-Fi steps in, supporting direct connection to the internet with bandwidths as high as 100Mbit/s.
Another consideration is the frequency of operation, and the choice here will be based on a combination of range, bandwidth and operating power. Many standards are capable of operating in both the Sub-1 GHz and the more common (and crowded) 2.4GHz range. Co-existence and resilience to a crowded spectrum may also be a design consideration, with some standards offering greater benefits in this area than others.
Typical Applications and solutions
In many cases the application will indicate which wireless technology to use. For example, a system which includes a number of sensors distributed around a building, each of which is in direct contact with a central controller (or Gateway), might be best implemented using a Sub-1 GHz technology based on a star network, while a star network avoids the processing overhead associated with a mesh network and would therefore allow the sensors to operate longer from a single battery.
With the right integrated solution, the low power nature of a Sub-1 GHz application of this type would allow a smart sensor to operate for as much as 20 years from a single coin cell battery.
As the IoT develops it has become apparent that a hardware platform (SimpleLink family) can be extended to address more application areas.
Connecting to the world
Of course, a major part of creating an application that forms part of the IoT involves connecting it to the internet, and in many applications the wireless protocol that most easily achieves this is Wi-Fi. A Wi-Fi connection provides global access to the functionality and data of an application, however the complexity of the protocol reflects this and is consequently more challenging to implement than, say, protocols intended for private networks.
As the value of data collected through distributed Wireless Sensor Networks (WSNs) increases, manufacturers are looking for reliable yet simple ways to create WSNs and start collecting that data. In this application area, Sub 1 GHz wireless connectivity can excel in both range and power
The CC3120, part of Texas Instruments’ SimpleLink Wi-Fi family, has been designed to make adding Wi-Fi to an application as easy as possible. It is a self-contained network processor with a fully-integrated web server and includes the TCP/IP stack needed to connect to the internet. Alternatively, the CC3220 provides even greater integration by including an ARM Cortex-M4 core dedicated to running application code. Manufacturers also takes into consideration security concerns seen in the growing IoT space. TI’s latest generation of Wireless Microcontroller provides multilevel security features that enable developers to protect their products against hostile takeover, as well as IP and data theft.
The latest revision of the specification sees Bluetooth 5 now supporting mesh networking, as well as an increased bit rate of up to 5Mbit/s. With the same low power credentials, it means Bluetooth can now be used in a wider range of applications that need a more direct internet connection, with the added benefit of greater range through the use of mesh networking.
The internet is enabled through the Internet Protocol, or IP; one of the latest wireless standards to provide IP functionality is 6LowPAN, as defined by the Internet Engineering Task Force. With full support for IPv6 on all nodes in a network It is perhaps the most future-proof of all wireless technologies, as it can operate in either the Sub-1GHz or 2.4GHz frequency bands and on a number of physical layers.
The IoT will be dominated by low power wireless technologies. In addition to those already mentioned, engineers are anticipating the wide scale availability of solutions targeting one of the latest protocols in this exciting and rapidly evolving application space; Thread. Unlike most other wireless technologies, Thread has been developed with just one objective; to provide a way to connect and control devices in the home.
Conclusion
Harnessing the capabilities of wireless connectivity has never been easier, thanks to highly integrated single-chip solutions and the availability of royalty-free software (including protocol stacks). The range of devices available covering all of the major standardised wireless protocols is now significantly accelerating the development of IoT applications.
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