Communication protocols

As an Alexien, you have surely heard of protocols, ZigBee, Z-Wave and others… But what is it? People using these terms seem so knowledgeable and on top of everything! And that annoys and it can even make you mean. So calm down, we'll explain what it is in a very simple way. No detail in all directions, no endless explanation. We are like that, we like popularization but not vulgarity.

A protocol? Did you say protocol?

But what is a protocol? Let's start from the beginning. Because everyone uses this word, but concretely, what is it? A protocol is, in the broad definition of the term on the Larousse, a "set of rules, questions, etc., defining a complex operation". If applied to computing, it is a set of rules defining the mode of communication between two computers, or between connected devices. Basically, it's the grammar of a specific language. And like all languages, the grammars are different. If you can speak English, you will be able to understand (or guess) a little bit of Dutch or Danish at best, but not Finnish or Japanese. It is the same for communication protocols between connected devices: a bulb operating under ZigBee will not be compatible with Wi-Fi or Z-wave, or at least without hack. Internet is a set of protocols in itself and TCP / IP, HTTP, HTTPS,…, are all rules of grammar.

But why use different protocols? Because each will have its advantages and disadvantages and will thus be more suited to a specific use.

Wi-Fi: 

Yup, Wi-Fi is a protocol. It's even the first in terms of use, because most homes, hotels, public places, etc., are provided with it via a Box. The vast majority of devices work via Wi-Fi: TV, PC, laptops, smartphones, bulbs, sockets, printers ... Governed by the IEEE 802.11 standards (this acronym probably tells you something), it will allow communication by radio waves between different devices.

The communication speed will depend on the type of Wi-Fi network: 11 Mbit / s theoretical for 802.11b, 54 Mbit / s for 802.11a or 802.11g, 600 Mbit / s theoretical for 802.11n3,4 and 1,3, Theoretical 5 Gbit / s802.11 for XNUMXac. When you look at the characteristics of your box or of an object to be connected to it, this will give you a good idea of ​​its power and therefore of the possible communication speed.

La Wi-Fi range is a few tens of meters without obstacles, hence sometimes the need to put repeaters to mesh routers. It has the advantage of being able to allow substantial data exchanges such as streaming, online work, internet browsing… thanks to its wide bandwidth. The problem with this technology is that it is easy to hack if not secure and is quite power hungry. Also, if you have a few devices connected, it will quickly saturate, especially if they are all connected on the same frequency, which is often the case since connected devices often operate on the same bands. In that case, you will go on mesh or CPL router to mesh your network and therefore dispatch your connections to several access points.

ZigBee:

 

Most of you must have heard about the ZigBee protocol through the Philips Hue, marks Osram or Trådfri but also thanks to theAmazon Echo More and at Echo Show 2.

Le ZigBee will allow communication between different devices via radio waves of low power frequency 868,42 MHz (therefore short distance) but also and above all in 2,4 GHz, such as Wi-Fi. It is governed by the 802.15.4 standards.

This protocol open-source has several advantages when compared to Wi-Fi:

  • It consumes very little energy : it is therefore quite possible to have autonomous wireless devices with batteries operating for several years. This is also why some manufacturers are turning to this technology (especially since it is free).
  • It is a protocol setting up a mesh network, that is to say that each device connected to this network will make it possible to extend the latter by serving as a relay, such as a Mesh for Wi-Fi. With this operation and the dedicated hub, your Wi-Fi network will be less involved.
  • Le production cost of a ZigBee node is less than Wi-Fi or Bluetooth products.
  • Installation simple devices that work with this protocol.

However, it also has drawbacks:

  • It requires much less amount of transferred data to work than Wi-Fi but transfer speeds are much lower. This is why it is only used for simple actions on simple devices such as light bulbs, switches… and not for streaming or anything else.
  • La radio frequency 868 Mhz is possible to jam. So drop this protocol for the alarms if they work on this band only… Also be careful that your bridge supports the radio bands of the ZigBee devices you buy. Most are in 2,4 Ghz but be careful if you buy them abroad, some devices may not be on 2,4 Ghz nor on 686 Mhz, but on 915 Mhz for example…
  • It cannot be understood natively by PCs, boxes or home networks (remember the grammar). Must therefore have what is called a hub or a bridge who will act as an interpreter between the Wi-Fi network and ZigBee. This is why some brands also sell you bridges more or less expensive or you have to use an Echo with an integrated bridge.
  • Due to thea security key specific to each connected device, it is necessary to follow a dedicated procedure to change a device of this type of network or even simply to change the room ...

Z-Wave:

 

It is also a “Z protocol”, like ZigBee, but not compatible with each other, specially developed for home automation.

Like the ZigBee, it allows communication between different devices via low-power radio waves with a frequency of 868,42 MHz (therefore short distance) exclusively. Z-Wave is a protocol based on proprietary technology, it was designed by the Danish Zensys but it is used by a large number of manufacturers.

 

In principle, it has the same advantages and disadvantages as the ZigBee but others should be highlighted:

  • As this is a proprietary protocol, manufacturers cannot change it as it can with the ZigBee. Thereby, all devices under this protocol are compatible with each other and operate on the same frequency.
  • Z-Wave works exclusively on 868,42 Mhz, very little saturated, and therefore allows better and much more stable communication. Your Wi-Fi network will be even less saturated than with ZigBee.

But beware, the only 868 MHz frequency band makes it more sensitive to interference. This can cause problems for single band alarm systems for example. But even if on paper it seems simple, the 128-bit encryption keys make it possible to secure everything effectively (like the ZigBee). Another negative point, the price of compatible peripherals is quite high...

That said, its inter-compatibility between different brands due to its proprietary protocol, its mesh network and the fact of not saturating your Wi-Fi at all means that it is the preferred protocol in home automation via boxes like Jeedom, Eedomus, Rapsberry ... But for some, to go up to the card, you are free to choose the protocol you like.

This is the end of this quick owner's tour of the most well-known protocols, in particular Wi-Fi and ZigBee for Alexians (Bluetooth was not discussed because it is used a little less by Alexa). There are of course others such as Enocean, Edisio… Purists will find these explanations too succinct, and will add “buts” or “No! "...

However, if they are purists, they are bound to know a lot more and do not need this article. On the other hand, we hope that thanks to these few lines your frustration has disappeared and that these protocol names are no longer bad words for you.

Did i choose Alexa or did she choose me? Let's say that as a beta tester, it's a bit of both! And I do not regret having met our favorite assistant nor this adventure undertaken with Alexien Modo. Technophile, self-taught and loving popularization, I try to make our common passion easy to access!