At the moment, sitting in your habitual chair you may be thinking how good it would be to switch off the light or open the window without leaving the spot. And if the chair is a few miles away from home, for sure, you would like to check if everything is okay in your accommodation. Well, Smart House would bring you both comfort and safety in this matter. If you already live in one, you could feel all the charm of this system.
Dreaming about implementing a similar project, you might be wondering how all the 'smart devices' understand each other and how your phone actually connects with them. I'll give you a hint: there are different radio protocols that allow to send signals at different frequencies. If you dig deeper in this subject you could get lost in a flow of various data. For a clearer understanding, imagine how many radio stations play at different broadcast frequencies.
Bringing an accurate idea of the above channels is the purpose of this article. However, the most exciting thing we are going to talk about is a new Bluetooth technology that may overshadow other means of communication at the level of "machine-to-machine". Well, let's go ahead.
What is mesh technology?
Imagine that you have a home automation lighting which can be controlled through your mobile app. How do you think all the light bulbs know when they should switch on?
The scheme is rather simple:
Step 1. The app gets connected with one of the light bulbs in the network (usually, it picks up the nearest one);
Step 2. The light bulb connected with the phone sends a signal to the next bulb;
Step 3. The second light bulb connects with the third bulb;
Step n. The process moves on until all the bulbs are connected and you see the light.
Watch this video to see how it works:
Trickle Algorithm Demo
The scheme described above is called mesh networking or wireless mesh. It implies a connection of multiple devices into a single system.
In practice, the algorithm of data transmission from one device to another is the most common one. Each unit acts as a node between the sender and recipient. In case one device gets broken, the signal is sent to the next unit located at the closest direction. For the clearer understanding, take a look at the image below.
Besides the above example, there is a so-called full mesh when every unit connects to each device in the network. Such scheme is more about theory than practice, though. You are unlikely to meet it in the smart house technology because of the complexity of implementation and, actually, the absence of necessity of usage. To get clear how it differs from the above scheme, pay attention to the image below.
The secret of identification
We have understood how the wireless mesh network works in whole, and now let's try to clarify which way the phone and bulbs actually 'see' each other and get arranged into smart home technology.
The secret lies in unique IDs assigned to each bulb in the network. When you want to switch on the light with the help of your phone, an app identifies the bulb ID and sends an appropriate command to it.
The simplified procedure of IDs registration can be described as follows:
- Account creation. At this step, the device gets registered at the site of the company, for instance, this one. After the registration, the user receives a unique account ID.
- ID assigning. The application searches for a light bulb that say (broadcast) "I am free". Once it is found, the user selects the bulb and the app joins it with the appropriate account and group, e.g., account ID A, group ID - B.
- Network creation. The light bulb starts broadcasting under the assigned ID. When the application switches it on or off, the light bulb interacts only with the bulbs connected to the same account.
- The light bulbs interaction. All the light bulbs around can hear the above bulb. If their account IDs coincide, they can communicate with it and through it.
Clarifying the details
At this point, I would like to answer possible questions which might have arisen after reading the above. Here, we go.
Why is the website registration needed?
The website is necessary to get a unique ID. If you create an account on the local phone without website registration you are likely to face the following troubles:
- Your account ID may coincide with the ID of already existed account;
- You face a risk to lose control over your lighting in case the phone is lost;
- There is no way to share the account with other devices.
In which case can I avoid website registration?
The website (server) registration is not necessary if you are not going to share the access among several devices. In this case, you can randomly generate the account ID and make it long enough to avoid a possible duplication.
How can I be sure that the given ID is not taken by the third party?
As it was mentioned, the scheme described above is significantly simplified. In reality, the server doesn't give the ID in a pure form but provides you with a key to authorize on the light bulb. Thus, the ID is encrypted and can hardly be obtained by anyone.
Getting to the main point
It is time to consider the channels of communication used to join our light bulbs in order to make a smart home lighting. Take a look at the radio protocols listed below.
WiFi - a network of a wide range capable of covering a huge area and maintaining the connection of a great number of devices. According to Chris Coley, a senior system engineer at Playground:
'Wi-Fi is a whole-home network'
Nevertheless, mesh WiFi network is not the most popular solution for house automation. Why so? The answer is simple: WiFi requires a significant energy consumption. It means that either you have to supply your devices with the batteries of a great energy storage or get them constantly connected to the electrical outlet. Besides the fact that such scheme is inconvenient, it is also very expensive.
ZigBee and Z-Wave, unlike Wifi, are considered to be the solutions of low energy consumption. According to Coley:
'A lot of home control devices that are primarily Zigbee/Z-Wave are primarily driven from a range and power consumption perspective by using a mesh network'
ZigBee and Z-Wave are often used for establishing the home lighting automation. Even though they have a similar operating principle, there are still some differences to learn:
- ZigBee is considered to be a universal one due to the fact that it uses standard frequency coverage of 2.4GHz ISM, thus, not requiring hardware tying to a particular country.
- Z-Wave functions on 915 MHz ISM band in the USA and 868 MHz RFID band - in Europe.
- Unlike ZigBee, Z-Wave uses it's own radio communication system supplied by Sigma. It should not be considered as a con, though, since Z-Wave is not much about compatibility problems as Z-Wave is.
- ZigBee and Z-Wave use different modulations. In the case of ZigBee, this is direct sequence spread spectrum (DSSS), in the case of Z-Wave - frequency shift keyed physical modulation (FSK). You can find out more here.
What is bad about ZigBee and Z-Wave?
Unlike WiFi or Bluetooth, ZigBee and Z-Wave are not built in nearly each device within arm's reach. For a clearer understanding, remember how many times you said: 'I'll send you a pic via Bluetooth' or 'Turn on WiFi, I'll send you a video'. I doubt you've ever said: 'Get your ZigBee on and accept the file'.
Here comes the disadvantage #1: you need special devices supporting these technologies.
Let's imagine that you've gathered the light bulbs supporting one of the protocols. The next challenge is to make your phone understand them. How to do that if it does not support the above way of communication?
The hub comes to the rescue. It acts as a bridge between the network of light bulbs and a mobile IoT applications which control them. Supporting ZigBee/Z-Wave it communicates with the light bulbs. Supporting WiFi it connects to the WiFi router, WiFi router - to the server, and server - to a mobile application. Take a look at the image below for better understanding of the scheme.
You might have understood that the disadvantage #2 implies that you need a hub to establish mesh networking communication.
To summarize the list of drawbacks, it should be mentioned that ZigBee and Z-Wave have a limited range of coverage. So, the disadvantage #3 says that you have to use many nodes to make all the network function appropriately.
Why not Bluetooth?
You may be wondering why to bother with ZigBee and Z-Wave if nearly each phone supports Bluetooth connection. Taking into account that it has a wider bandwidth than above protocols, highly secure encryption, and a low power consumption, this option seems to be an obvious choice for smart home control.
The reason is heavy: for now, Bluetooth does not support mesh technology.
Imagine that you have three devices. The signal from the first device comes to the second device via Bluetooth. However, you need the signal to be redirected to the third device. In this scheme, the second device should be acting as a node. This is what Bluetooth cannot do at the moment.
As any fairy tale, our article is going to have a happy end:). According to the recent announcement, Bluetooth is to support mesh networking in the nearest future. According to Sven Mattisson, Bluetooth co-inventor:
'50bn IoT machines is just the start'
Just imagine the globality of plans of 'blue' technology and the level of expected connection!
The breaking news means the following for smart house systems:
- You don't need a hub for setting up a connection between a phone and devices;
- You can place the devices of your smart lighting (or any other smart solution) at a significant distance from each other without being afraid that the signal could be lost;
- If not far away from the network of devices, you can manage them without the Internet connection.
The guesses and expectations
Which changes should we expect from the upcoming release and a new level of Bluetooth connection? Well, this is hard to predict. However, one thing is clear enough - Bluetooth is growing into a dangerous competitor in the fight for IoT space and smart home products.
Given that the Internet of Things is a trend of present days we are excited to see how the events are going to develop. Will there be any counter-move from ZigBee, Z-Wave, and other radio protocols deployed at the moment? Are they going to do any steps forward to spread their technology? We'll see!
Share your thoughts and comments if you know more about this subject! We will be glad to learn new things and answer any questions. Contact us for any information you need and subscribe not to miss the upcoming discoveries and events!
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