Talking to each other in a Smart Home – Part 1

No, it’s not what you think. We haven’t stopped talking to each other after we made our home smart. I mean, I wasn’t referring to not having to tell the wife to switch off the lights… I refer to how your smart devices talk to each other in your home.

Now in order for devices to work together, they must be able to talk to each other, just like how we must be able to convey our intentions to our colleagues in order to collaborate. Here I give you a quick introduction to the types of communication protocols that are common to smart home devices.

No one will understand each other if we all spoke a different language.

While the list below is not exactly languages, it helps us understand what it means to us as end users. I will briefly explain each protocol, starting with those that we are most familiar with however note that this is not a technical discussion. It is meant to help the layman understand the different protocols enough to use them properly – the same way most people don’t even understand how the gear train of a car works before they can drive it – they just understand enough what each gear does and how it helps achieve their end goal.

Explain why it is not possible to put your car into first gear directly from fourth at 90km/h.

While you may not need to comprehend how something works in full detail, you need to understand just enough to use it properly – said me.

In general, list of “languages” includes:

  1. Wi-Fi
  2. Bluetooth
  3. ZigBee/Z-Wave
  4. Proprietary systems

Covering all of these in a single sitting can be an information overload, therefore I will split this into 2 parts. Today we shall cover the more straight forward ones – Wi-Fi and Bluetooth.

1. Wi-fi

This is the easiest to understand, since most people are familiar with this term and how it roughly works. A Wi-Fi device, let’s say switch, works by using the existing Wi-Fi network in your home. This is not limited to Wi-Fi switches – smart speakers, TVs, Google Home, Alexa, Chromecast etc all work on Wi-Fi. It does this by communicating with the Cloud via your router at gimme home router.

In a general sense, the below image explains what goes on in your home. When you turn on a switch (physically, with your hands), it sends a signal to the router, which then passes it to the Cloud – the status of your switch is now “ON” and is stored in the Cloud.

How the Wi-Fi Switch communicates with the Cloud to show you a “live” status on your phone

When you open the app on your phone to check on the status of the switch, your phone then pulls that status from the Cloud and presents that on your phone. Without this cloud, you will not be able to know if your switch is on or off, which means you may be turning the light on when in fact you want to turn it off. Note that your phone never really communicates directly with the switch.

A couple of more reputable companies making Wi-Fi Switches are Sonoff, Belkin, TP-Link Kasas and D-Link.


  1. Closest to “plug and play”

The advantage is clear with this one – you just buy a device and connect it to your Wi-Fi network.


  1. Require internet to work
  2. Limit on number of devices

The disadvantage is you would require an internet connection for stuff to work with your phone The switch that is physically connected to your light should still work when triggered manually by hand, so you would still be able to turn on/off your appliances at home. Just that you can’t do it over Wi-Fi or your phone.

Another disadvantage is the limit on the number of devices you can connect to your router. This limit includes your mobile phones, laptops, TVs etc, which is easily 4-10 devices depending on the size of your home. The rule of thumb is to not go beyond 32. Depending on how extensive your set up is, you can very easily max this out.

2. Bluetooth

Next, you should also be fairly familiar with the term Bluetooth, although a good 50% of the people I speak with do not really have an understanding on how it works (disclaimer: statistics not backed by data).

Compared to Wi-Fi, Bluetooth works over much shorter distances, data transfer is slower and it uses less power. Bluetooth also does not require an internet connection to work. This is why you can use your bluetooth headset when you’re flying over the Pacific Ocean, or beam music to your in-car stereo even when you have exceeded the data quota for the month.

That said, Bluetooth within a smart home will work slightly differently from the above.

Connecting your bluetooth device at home – without cloud

First, you will need a HUB. This is because while the Bluetooth device (say light bulb or lamp) can connect to your phone directly, it will stop working if you head out of home, since your phone is the only one that understands the bulb (thinking about speaking a common language). On the other hand, if you connect the bulb to a HUB, which can be connected to a router, then the bulb will always have “someone to talk to”. Because the HUB is connected to the router, your phone, when connected to the same router, is able to talk to your bulb via the HUB.

Note that in this set up we do not necessarily have to connect to a Cloud. The advantage of Bluetooth is that it can technically work offline. However you can still connect it to a Cloud if you prefer. This allows you to control the devices when you are, say, at work (away from home). More on that in future chapters.

Bluetooth communication routes in a smart home – cloud is optional


  1. Ability to work offline

As above, this is one of the advantages of this system.


  1. Bluetooth has short range

As mentioned above, because of Bluetooth’s relatively short range, if your HUB or phone is too far away from the device, it will not work because it “cannot hear” what each other is speaking. You need to be able to shout loud enough or place the devices close enough – typically 2 to 3 metres without any obstructions in between. This is a major disadvantage for home automation because you need all your devices to work as seamlessly as possible with minimal ‘breaks’ in the network. Think of it as a direct, non-stop flight vs a flight with stop-overs.


Alright, let’s take a break and allow you to digest all of these information. We will cover ZigBee, Z-Wave and other proprietary systems in our next post. Meanwhile, do you now have a better understanding of how these systems work?

Please reach out if any of the points above isn’t clear!

Image credits:
Original Wi-Fi symbol taken from freepik. Modified by HouseToSmart.

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