ZigBee and others explained

You've likely heard of the phrase "home automation" and a related specification called ZigBee and simply assumed they are nerdy things within a niche industry.

Well, that's not true. For instance: Google has Nest, Apple has HomeKit, and Samsung is thinking about buying SmartThings. These acquisitions and frameworks prove that even the biggest companies in the world are thinking about and developing ways to make your home smarter. And some of these ways might use ZigBee.

That doesn't mean ZigBee isn't a complex idea to grasp. The home automation industry is emerging, evolving and welcoming new players by the second. It's the future; the movement that will supposedly change your world. But what exactly is ZigBee and how does it affect home automation or even you?

Pocket-lint is here to supply the answers.

Home automation

Home automation occurs when everyday objects in your house are connected and participating together on a single system. It is also the convergence of conventional connected devices and smart appliances‏.

Home automation could allow you to wake up and experience the "ideal" day. You could wake up in the morning to a fresh pot of coffee, for instance, because you've programmed the machine to start brewing 10 minutes before your alarm clock went off. Your home heater might have also turned on 30 minutes before, so it would have time to warm up your bathroom.

All of these connected devices are being handled by automatic systems over a single network. The result? You have a smart home, thanks to smart applications and devices. But there's just one problem: many companies make different devices. In order to get them to work together on a single network, you have to use a single common language. That's where ZigBee comes in.

ZigBee

ZigBee is based on the IEEE’s 802.15.4 personal-area network standard. All you need to know is that ZigBee is a specification that's been around for more than a decade, and it's widely considered an alternative to Wi-Fi and Bluetooth for some applications including low-powered devices that don't require a lot of bandwidth.

ZigBee is for sensor-monitoring and control of various applications/devices from multiple companies, because it lets ZigBee-enabled devices work and operate together while also giving you the ability to control them. Hence why it is ideal for home automation.

A typical example is when you own a smart light bulb (that is ZigBee-enabled) and a smart light switch (that is also ZigBee-enabled), and you want the light switch to communicate with and control the light bulb. With ZigBee, the two devices - even if they're from different manufacturers - speak a common language.

ZigBee does not focus on the point-to-point market, such as Bluetooth, where one high-powered device sends data to another high-powered device over a short range. It's also not for standard wireless uses like when you would stream audio or movies.

You should only use ZigBee if you need to send data across a large area, where it traverses multiple hops, and all the devices you want to control are low-powered or even battery-powered. For this reason, ZigBee is most used in industrial and home automation systems (such as a wireless light switch for a lighting setup).

Keep in mind that while ZigBee's network layer supports both star and tree typical networks, it's often associated with a mesh network.

Mesh networking

A mesh network is when a network connection is spread out among wireless nodes that can communicate with each other and share a network connection across a large area. Think of nodes as small radio transmitters that function in the same way as a wireless router. ZigBee's ability to support mesh networking means it can boost data transmission range and provide greater stability (even when a single connected node fails and doesn't work).

ZigBee nodes can be coordinators, routers, and end devices. Coordinators establish the network and store information like security keys, while routers act as intermediate nodes and relay data from other devices. And finally, end devices are low-power gadgets that can communicate with coordinators and routers but cannot transmit data to other end devices.

In other words, with ZigBee, you will likely have a master coordinator node that controls other connected nodes. If one node fails for some reason and cannot communicate with a second node on the mesh network, the master node and second node may communicate by linking to a third node within range. Every node acts as a repeater of sorts, and all nodes cooperate in the distribution of data in the mesh network.

ZigBee supports up to 65,000 nodes on a single network.

ZigBee vs Wi-Fi

Unlike ZigBee, Wi-Fi is based on IEEE 802.11. But you can use either ZigBee or Wi-Fi (or even a number of other alternatives) to connect objects in your home and achieve ultimate home automation.

ZigBee is for applications/devices that require a low data rate, long battery life, and long range. That said, you should examine the following four characteristics prior to deciding whether you want to use ZigBee or Wi-Fi for your home automation setup:

Power

The most common devices that use Wi-Fi are laptops and smartphones, and they usually have a battery life of 1 day or sometimes 2 days before they need more power. On the other hand, common ZigBee applications, such as the light switch we mentioned earlier, have a longer battery life of up to 7 years.

The standard you should use will directly relate to the type of device you have and how much power it needs.

Bitrate

Wi-Fi has a max bitrate of 54 Mb/s, while ZigBee allows 250 kb/s. Because there's such a huge difference between the two standards, you should consider the highest amount of through-put you want to achieve or how much data you plan to transmit. ZigBee is for applications that require a low data rate.

Range

You can typically access Wi-Fi when in a 100-metre range. ZigBee supports a 1,000-metre range. You'll therefore need to use ZigBee if you're planning to be 1,000 feet from your home automation application.

Topology

A Wi-Fi setup involves an access point and clients. If you have an ethernet network, you can use several access points to extend your range. You can then use wireless to connect access points to your clients (exactly what laptops and smartphones do).

Although ZigBee still uses ethernet, it doesn't use access points. It has a gateway that provides connectivity to distributed nodes and transmits back to the ethernet. The nodes have a wireless antenna and communicate wirelessly using ZigBee. To extend your range, just add more nodes.

A single Wi-Fi-based network can have a network size of up to 2,007 nodes, whereas ZigBee-based networks can have over 65,000 nodes.

In a home automation situation, ZigBee is the better choice if you have tonnes of nodes (that require a long range) and you need them all to be decentralised and capable of communicating with each other should a node on the network fail.

ZigBee Alliance

The ZigBee Alliance was established in 2002. It's a consortium of companies and other organisations that support the development of ZigBee and promote its use. It also performs interoperability testing, certifies products, and maintains the IEEE 802.15.4 standard.

There are more than 400 Alliance members and 600 certified products. Members include promoters (such as Philips and Texas Instruments), participants (such as Belkin and AT&T), and adopters (such as Logitech and Motorola Mobility).

Promoters have representation on the Alliance's Board of Directors and hold voting rights. Participants hold voting rights too but play a more active role in evolving ZigBee and receive early access to specifications for development. Adopters are members that receive access to completed ZigBee specifications and standards.

ZigBee alternatives

Yes. There are many alternatives to ZigBee that target the same general applications. Some alternatives are more versatile and be configured for any kind of short-range wireless task, while others are more complex and require longer development times. One of the more notable alternatives is Z-Wave.

Z-Wave has an alliance, just like ZigBee. The Z-Wave Alliance is a consortium of more than 250 manufacturers that build wireless home control products based on the Z-Wave standard. There are more than 900 different products certified by the Z-Wave Alliance, though that number is constantly growing.



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