A tale of five Ebook protocols The ultimate guide to the IoT wireless communication Revision 3.0 landscape February 2018 2018 EDITION Ebook by Silvair Table of Contents In pursuit of interoperability 3 Can we talk? 5 Why not Wi-Fi? 8 Riding the Z-Wave 13 ZigBee – is the sting still sharp? 19 THREADing the way through a connected home 24 Bluetooth: a technology in transition 30 And the winner is... 40 Copyright © 2018. All rights reserved. page 2 Ebook by Silvair Introduction: 1 In pursuit of interoperability Companies venturing into the IoT market are facing some difficult choices. One of the crucial de- cisions they need to make relates to the wireless communication technology their future smart products will employ. At the most basic level, the IoT is all about connectivity. The idea is that countless numbers of smart devices are able to communicate seamlessly, producing massive benefits across all aspects of our lives and having a remarkable impact on our society. The reality, however, is still far from that concept. At this early stage of market development, the Internet of Things is heavily fragmented and lacks interoperability. A recent report from McKinsey Global Institute predicts that the global economic impact of the IoT could reach even up to $11.1 trillion per year by 2025, representing 11% of the entire world economy. But at the same time, it identifies several major obstacles on the road to this IoT promised land. Topping the list is the problem of varying standards which prevent devices and systems from communicating with each other. According to the report, interoperability is required to capture roughly 40% – and in some cases, as much as 60% – of the potential value across IoT applications. The matter of interoperability does not revolve solely around connectivity protocols. Barriers also include lack of standard data formats or common software interfaces. Yet, getting smart devices to talk to one another and interoperate is an elementary need that must be met to make the connected world a reality. page 3 Ebook by Silvair A number of wireless communication technologies have attempted to dominate the smart home and connected building automation market, but so far none has emerged as a clear leader in this race. Each brings certain attributes to the table, and each approaches the challenge of interoperability in its own way. In fact, the differences between them are often so fundamental that drawing a direct comparison is virtually impossible. And while it’s still uncertain whether all the specific needs of various industries and environments can be addressed by a single universal connectivity solution, only the fittest will survive, eventually becoming the global standards for the IoT. This will benefit vendors and end users alike, contributing to further market growth and accelerating mass adoption of connected products. This situation mirrors the challenges faced by the technology industry in the early days of network- ing. A number of competing protocols proliferated back then, including IBM’s SNA, Xerox’ XNS, Novell’s IPX/SPX, Apple’s AppleTalk and many others, but it was TCP/IP that emerged as the protocol of choice for most networking applications, eventually becoming basically synonymous with the technical definition of the Internet. Without agreed-upon protocols and standards, the Internet and the World Wide Web would not have become what they are today. With the Internet of Things, history is repeating itself, although on an incomparably larger scale. Eventually, the “things” of the IoT will also learn to communicate with each other, but until that hap- pens, device makers are forced to make bets in an immature environment. This creates both certain complications and risks, as well as big opportunities. Some of the communication technologies will inevitably fade away over time, forcing all the companies utilizing them to retool and switch to other solutions, in the meantime withdrawing their products from the market. But those who bet on the winning horse will enjoy all the benefits of being ahead of the curve. So which of the available communication protocols is most reliable? Which offers the most for man- ufacturers of smart products, and has the greatest potential to survive the standards war, eventually becoming the go-to technology to connect the IoT? These are some of the questions we will try to answer here. We feel that we’ve learned several important lessons that we can share on this matter, since we also had to face the same exact dilemma, being fully aware of how significant the conse- quences of our decision would be. Wireless connectivity is behind everything we do, so we have put an enormous effort to ensure that we know each of the available solutions inside out, and that we are able to identify all of their strengths and weaknesses in particular applications. Our goal is not to promote one or another communication technology. Our goal is to make every- thing connectable, and interoperability is the only way to get there. So our guide to wireless com- munication protocols is, in fact, a guide to interoperability. Hopefully, these resources will prove valuable to manufacturers who are aching to get into the exciting market of connected devices, but still hesitate, being unsure of which technology to embrace. page 4 Ebook by Silvair Can we 2 talk? First things first. What are communication protocols and why do we need them to make our homes and offices smart? Simply put, a protocol is a set of predefined rules that are followed by two or more devices in a network to establish reliable communication and successfully exchange data between each other. For the Internet of Things to become a reality, an enormous part of this com- munication has to be wireless, and so a wide range of machine-to-machine wireless connectivity technologies have emerged over the past years. Features most of them have in common include low energy and low bandwidth requirements, as this radically extends battery life and allows mul- tiple devices to be used within a limited space. With radio being a shared medium, frequency bands are very scarce resources. In order to accommodate many devices in a given frequency band, the requirement for them to be low bandwidth is extremely important. Since many popular radio protocols have numerous overlapping qualities, at first glance it might seem that all of them basically do the same job. But as we already mentioned, there are fundamental differences between them. Some wireless communication technologies do completely different things than the other ones, and were developed with different goals and assumptions in mind. This becomes clear once we look at how they relate to the OSI reference model. page 5 Ebook by Silvair The International Organization for Standardization (ISO) developed the Open Systems Interconnec- tion (OSI) model back in the 80s to provide a framework for the coordination of communications standards development. To this day, it remains the primary reference model for network commu- nication. The OSI framework breaks the network communication process down into a manageable hierarchy of seven layers. Each of them has a specific function and deals with clearly defined tasks, interfacing with the layers located directly below and above it. The 7-layer OSI reference stack looks as follows: Application Presentation Session Transport Network Data Link Physical The name of each layer tells a bit about the types of services provided there. We won’t describe all these services and tasks at this point; the OSI model has been around for ages and there is plenty of detailed information about it all over the Internet. However, we will keep returning to the above stack in this document, explaining where on the OSI model a particular connectivity solution op- erates, and what consequences this entails both for end users and manufacturers. That’s because the OSI model is where the fundamental differences between individual protocols originate from. Some of the standards aspiring to connect the IoT define only a small part of the 7-layer OSI refer- ence model, while relying on other available technologies to take care of the remaining aspects of communication. Others go all the way from the physical layer up to the application layer. By itself, this does not make any of them better or worse. What it means is that they are often based on com- pletely different principles, and this is something one should be aware of when trying to answer the question “which technology will be the best one for my application?”. Another important thing is that there is no perfect technology. Different applications have different requirements, and there is no one-size-fits-all solution. Back to the OSI, in order to better visualize this 7-layer concept and how the protocols fit into this model, you can think of it as a framework for communication between humans. This might not be something we pay any attention to, but two persons who want to communicate with each other must share certain clearly specified rules. Just like protocols. Similarly as in the OSI reference model, these rules can be easily broken down into a number of layers. Starting from the lowest one, i.e. the physical layer, humans also need what can be called a physical infrastructure for their communica- tion. In the case of verbal communication, this would include such mediums as voice or sound in general. Human speech organs would also fit somewhere in the lower part of the OSI layer, and as we move towards the top, our communication rules would become more narrow, specifying phones, phonemes, words with their various meanings, grammatical structures, and so on.