Today smart home development is at its early stage, but industry analysts forecast the market growth at more than $50 billion by 2022. No wonder that more players are launching new home automation projects to get their share of the market – and often fail, being unable to include disparate devices into one ecosystem and provide effective connectivity between them. So it is better to get a clear idea about standards and their performance right from the start.
Connectivity Protocols Market: Searching for ‘One-Size-Fits-All’ Solution
Connectivity lies at the heart of IoT development, including home automation projects. However, there is no ultimate connectivity solution which will assure its effective and stable functioning whatever the case may be. Today fragmentation on the market of IoT connectivity standards is very high and is often referred to as one of the key constraints of the market development.
Why do smart home project owners need to configure connectivity standards from the start?
- The chosen protocols need to be widely adopted by device manufacturers, otherwise their maintenance will never pay off.
- Maintaining many different standards comes at a high price. Setting an aim to configure as many connectivity standards as possible within your project ecosystem will be a waste of precious resources.
- Using the standard chosen for your smart home product must be as user friendly and seamless for the end customer as possible.
There are several standards on the smart home market, and while some of them are applied to all IoT projects (Wi-Fi, Bluetooth), others have been developed to tackle the specific requirements of smart home projects (ZigBee, Z-Wave, Thread).
Why not Wi-Fi?
Wi-Fi is ubiquitous: it is present by default in every home, as a result all smart home devices are developed as compatible with this protocol from the start.
Then, why hasn’t it become a silver bullet solution for smart home projects?
- Extremely power intensive protocol. Wi-Fi is a suitable solution for transferring data-heavy content, like video and audio, but this comes at a price of battery draining. A smart home project is much less power consuming, as it is based upon the work of sensors and controllers, which broadcast simple commands (e.g. on/off), state change signals, and small bits of data (e.g. sensor data).
- Topology of a Wi-Fi network. Wi-Fi network has a central gateway, i.e. a router, which handles all the traffic. If it fails, individual nodes of the network cannot communicate with each other anymore – and the whole smart home ecosystem fails to work.
- Complexity of the setup process. For any solution to become widespread, it must provide a flawless user experience. In the case of Wi-Fi, one needs the assistance of a specialist to deploy a Wi-Fi network for a smart home system.
As a result, Wi-Fi is a great fit for the Internet of People, interested in streamlining heavy content like video and audio files. However, it falls short when applied to the Internet of Things.
Choosing the Right Protocol for Your Home Automation Project
So, if Wi-Fi turns out to be a non-ideal solution for home automation structures despite its ubiquity, what are the alternatives chosen by custom applications development companies?
Z-Wave
This low-power wireless communication protocol appeared in 2001 and since then has become widespread in the world of smart home solutions. The notion ‘widespread’ is not to neglect here, as it means that a growing number of smart home devices manufactures are making their products compatible with the Z-Wave protocol. Today there are more than 2,400 interoperable products from more than 700 leading worldwide brands on the market. Moreover, even if developed by different manufacturers, these devices have an in-built compatibility with each other.
Z-Wave is a classic mesh technology solution. Its work is based upon a system of connected devices, i.e. nodes, which get interconnected in a non-hierarchy, direct and dynamic manner for routing data from one node to another over the covered area.
This type of functioning contains its key advantage: messages can reach their destination via multiple hops, not depending on a central gateway and its stable functioning.
Then, what prevents Z-Wave from becoming the gold standard in the smart home connectivity industry?
- Shortcomings of the Source Routing Algorithm (SRA). With source-based routing, a device which initiates data transfer generates a complete route through the mesh network to the recipient. Possible communication routes are built by the primary controller, i.e. a device which analyses the entire network and comes up with optimal routes between its nodes in the form of ‘routing tables’. If one of the nodes fails, e.g. a bulb burns out or a device goes down, the primary controller starts a network healing procedure, which takes up to 1-2 hours, to update the whole network and its routing tables.
- Limited scalability. First, a Z-Wave network contains up 232 nodes in a structure. Today a typical smart home contains less than this number, but an expected expansion of home automation sensors and other connected devices (Gartner predicts that within a couple of years there could be more than 500 smart devices in a typical home) will be putting more and more pressure on the protocol, making the Z-Wave alliance augment this number. When it will happen and how stable a greater network will work remains an open question today.
Second, Z-Wave provides for up to 4 repeating nodes between 2 routing nodes. With a typical indoor range of a Z-Wave module around 50m indoors, a Z-Wave network allows to transmit data within an average apartment, but can be insufficient for a greater surface.
ZigBee
ZigBee is another popular mesh solution on the market – and the key competitor of Z-Wave, which has overcome some limitations of the latter:
- Proprietary vs. Open source. Z-Wave is a proprietary protocol run by Silicon Labs, while ZigBee is an open protocol solution run by the ZigBee Alliance. In practice this means that Sigma Designs, acquired by Silicon Labs in May 2018, licenses Z-Wave for a fee, and devices using this standard can be pricier than those using the other protocol.
- Destination-based routing. With this type of routing, forwarding a packet depends only on the destination of the packet and is independent of the choice of a particular optimality criterion for paths. As a result, ZigBee presents a self-healing network, which can quickly reroute data packets to ensure they reach destination should any of the nodes fail.
- Extreme scalability. Zigbee can support way more devices when Z-Wave – in fact, the number exceeds 65,000 nodes in one network. Hence, it can provide enormous coverage despite relatively low range of individual modules (10-20m indoors).
Besides, ZigBee doesn’t have a limitation of 4 repeaters between the two interconnecting nodes.
Looks like ZigBee has tackled the principal problems unresolved by its competitor? Don’t rush into conclusions.
Among its main shortcomings one can list:
- Interoperability remains the principal problem of the ZigBee protocol. The Zigbee Alliance, interested in attracting more device developers and making it easier for them to implement their protocol, broke its solution into standardized protocols: Home Automation, Smart Energy Profile, SEP energy management, Light Link, digital health, home hospital care, and more. Each of the protocols specifies the pattern of communication between smart devices of the same category – but doesn’t oblige device manufacturers to adopt these pre-developed profiles, which has led to many developers establishing their own proprietary connectivity solution. As a result, we have many devices classified under the same Zigbee protocol which don’t interoperate with each other.
Hence, technical fragmentation which remains the principal problem in IoT, doesn’t get resolved within the Zigbee ecosystem. Moreover, it gets even sharper.
- Low speed. Though quicker than Z-Wave (250kbit/s vs. 100kbit/s), it still cannot be compared with the speed, let’s say, of Bluetooth (2 Mbit/s). This relatively low speed can be sufficient for transmitting simple commands and small data packets. But taken into account a great number of nodes which can be included into a Zigbee network, their stable functioning can be seriously challenged.
Thread
Compared to the previously mentioned solutions, Thread is a relative newcomer which was launched in 2015. It was developed and presented as a connectivity protocol for smart homes, tailored to its specific requirements.
From the technical standpoint, its main advantage is the dual-mesh principal of work. Thread uses both wireless and hardwired communication; as a consequence, the devices in its protocol communicate even when the Wi-Fi network goes down.
The technology was warmly welcomed by tech specialists and IT journalists, who named Thread ‘a mesh protocol that works’ soon after its release. The expectations were high – but here are some stats: as of the time of writing, only 15 technologies are marked as Thread certified, and 2 – as Thread ready (which means that they have applied not all core features of the network protocol but have picked up only some of them). The Thread technology was launched when some well-reputed technologies had already taken their share, and it didn’t manage to offer a solution efficient enough to become an ultimate leader in the eyes of IoT developers.
In order to overcome this limitation, the Thread Group and Zigbee Alliance announced their partnership in 2016, aimed at creating an interoperable solution between the two standards. As a result of this partnership, a new specification has appeared that uses Zigbee’s open application layer called Dotdot over a low-power wireless Thread network.
So far this remains one of the brightest examples of key smart home industry players cooperating in order to address the fragmentation of IoT protocols.
Solving the Interoperability Issue: Here Comes the Hub
Though the above-mentioned solutions turn out to be more effective for home automation projects than Wi-Fi, they bring about a new problem, i.e. the interoperability issue. Devices need to be connected not only to the smart home network, but also to each other in order to realize the full potential from IoT.
To pull the technologies together, a hub is needed. It collects and translates protocol communications from smart home devices, hence, even if one device supports Wi-Fi and Bluetooth, while another uses a mesh technology, their signals are collected by one centralized point, which ties together all the devices into one ecosystem, translates different protocols to each other and acts as a single application for the end user to rule all the elements of this ecosystem.
Today on the market one can find smart home hubs of different types:
- Dedicated smart home hubs. SmartThings, Wink, and Harmony are the most well-known solutions, developed with the main aim to make different protocols work together. Technically they are the most exquisite ones, which can do much more than just ‘translate’ sensors and switches to each other. Dedicated smart home hubs let their owner customize the whole network by performing some processing and automating things that the manufacturer didn’t provide by default.
- Smart speakers. Amazon Echo and Google Home are not technically defined as hubs, but in most situations can replace the latter ones, when additional configuration is not needed. Moreover, controlling a smart home with the help of a voice assistant has become a widespread practice.
- Software hubs. Yonomi, Wink (which can be pretty useful without its hardware part), Stringify and Elgato EVE can be set up on a smartphone to control the devices in a smart home structure with no need to buy a physical router type of device.
While more and smarter home devices are coming to the market, developers are trying to integrate them all ineffective home automation services, where all switches and sensors work as an orchestra. However, today connecting all these devices into one ecosystem is not an easy task, as the connectivity standards market is fragmented, and many technologies are still under development.
