25

Basically when it comes to IoT, the two main communication methods which come to my mind are either Bluetooth or Wi-Fi. I know that there are others as well like ZigBee, Z-Wave but I would like to stay at either Wi-Fi or Bluetooth as they are supported by smart phones and tablets by default.

Application overview, system specifications:

  • No HD cameras in any device.
  • Purpose is to have connected all the locks, both windows and entrance doors and even dog doors.
  • All light switches should be connected with feedback information about the current state of the particular lamp. (Switches can be controlled remotely and manually as well.)
  • Be able to handle proximity sensors several ones per room.
  • I want the system to be able to handle smart air conditioners (these should be controlled remotely and be able to give feedback about temperature and humidity values.)

In general, I have a lot of devices with low bandwidth requirements and the main goal is to have a system that is as scalable as possible. So if I move to a twice as big house which needs almost twice as much sensors, I want it to be the easiest to install the additional ones.


Now I know the basic advantages and disadvantages of the two compared. It is listed at this site Bluetooth vs. Wi-Fi (the image is taken from here as well).

Comparison of BlueTooth and Wi-Fi

To highlight: Some Bluetooth is cheap and easier to use. However, Wi-Fi is more secure, has a higher range and bandwidth but, of course, costs more.


So the question is: At the dawn of a project, how can one decide which one will be the more suitable for the task? I consider the scalability as the most important spec.


  • 2
    It depends upon connection utility, range, and purpose of the device. Bluetooth devices have limited range and little or no security, if you have pass key you are paired. – Chinmaya B Dec 6 '16 at 18:51
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    Bluetooth 4.x ought to be secure. It should have more sophisticated pairing functionality too. Fey factors are throughput, range and available energy at the endpoints. – Sean Houlihane Dec 6 '16 at 19:07
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    Your chart answers most the qustestion – Mahendra Gunawardena Dec 6 '16 at 23:22
  • Is WiFi really more expensive? I tried to look for Bluetooth modules for Arduino (probably the cheapest choice for BT?) on Chinese stores and they cost about 1,70 Euro, the same price of ESP8266 modules. Consider however that the ESP8266 may be used alone without any additional controller (it can be programmed easily), while the BT modules are just "modems" and require an external controller to send and process data. – FarO Oct 2 '17 at 13:43
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Wireless and Bluetooth are very close technologies. But, when to choose between one of them you have to consider many things.

Speed:

Bluetooth 4.0 offers 25 Mbps while WiFi Direct can offer you 250 Mbps. So if you want a faster transfer rate, i.e. if you need to transfer large amount of data within a short time, and it is your main concern, go for WiFi.

Range:

Bluetooth 4.0 has three different types, where the range is mostly device dependent. But we can expect 100 ft to 200 ft range from it. WiFi Direct has a range of around 600 ft, which can be vary on the real world scenarios, but seemingly, wifi can transfer data to longer distances.

Security:

WiFi Direct is using WPA2 with AES 256-bit encryption, while bluetooth 4.0 uses AES 128-bit encryption. But both of these security measures can provide enough security for most of our tasks. Why bother?

Power Consumption:

Bluetooth 4.0 has a separate mode called Bluetooth Low Energy (LE) where power consumption is very low. WiFi Direct in the other hand has also been said it have low power consumption, but in this case Bluetooth is probably the winner.

Cost:

When we build IoT devices, we also have to consider the cost. Bluetooth is clearly low costing technology, where WiFi is still somewhat expensive. This should also be concerned when you select the technology.

So, you can select any of these technologies according to your need.

  • BT modules on Chinese stores are a bit less than 2 dollars, the same for ESP8266 modules. The former however require external controllers, the latter can be programmed and used stand-alone (12 usable GPIO). – FarO Oct 2 '17 at 13:45
10
  • Bluetooth Classic: If line power is available, and the application is a data intensive application such as audio streaming
  • Bluetooth Low Energy: If the data rate is low and device is powered by battery.
  • Wifi: Base on current available technology, if line power is available and application requires large amount of data.

So for a smart home device, user base, application, region and the supporting echo system might detect the which protocol suits best. Currently in the US there few competing echo systems such as Lowes IRIS, Wink, smarthings are creating networking hubs that support BLE, Zigbee and Wifi. Therefore BLE might be good choice. Also in such cases security can be off loaded to the hub.

On the contrary if the device is not part of a echo systems, and requires higher data transfer rates such is a security camera, then wifi becomes a good choice.

7

Basically, you trade off bandwidth, range and cost.

If one of the choices does not meet your requirements for bandwidth or range, then your choice is clear.

If both meet those requirements, then it is a business decision, and you would probably go with cost.

Of course, this implies that you are providing both client and server. If you are, for instance, developing a new client to interface with an existing server, then your choice is dictated.

  • 1
    Yes ! Exactly. Considering whether we are developing both the server and the client, or the client only, will effect the decision. – Thisaru Guruge Dec 7 '16 at 10:49
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Another factor to consider is radio packet size, which is much smaller for Bluetooth than for WiFi. This means that the collision risk is lower for Bluetooth than for WiFi, and a Bluetooth transmission is more likely to disrupt a WiFi transmission than vice versa.

5

I have reached a conclusion that the Bluetooth will be a better choice with its upcoming new release of Bluetooth 5. Reference.

Kirkland, Washington – June 16, 2016 – The Bluetooth Special Interest Group (SIG) announced that its next release, coming late 2016 to early 2017, will be called Bluetooth 5 and will include significantly increased range, speed, and broadcast messaging capacity. Extending range will deliver robust, reliable Internet of Things (IoT) connections that make full-home and building and outdoor use cases a reality. Higher speeds will send data faster and optimize responsiveness. Increasing broadcast capacity will propel the next generation of “connectionless” services like beacons and location-relevant information and navigation. These Bluetooth advancements open up more possibilities and enable SIG companies – now at an all-time high of 30,000 member companies – to build an accessible, interoperable IoT.

As others have pointed out I trade off bandwidth, range and cost. But with this new promising Bluetooth release I will get the following advantages according to Texas Instruments. And there probably won't be a trade off at all.

  1. Longer range will enable point-to-point and star networks to provide reliable, whole-house coverage for smart home applications such as security systems, lighting, smoke detectors and door locks. TI’s SimpleLink ultra-low power wireless MCUs provide industry leading RF performance to enable longer range and more robust connectivity today, and will introduce up to four times longer range with Bluetooth 5. Longer range will also be a huge advantage in mesh networks, reducing the number of hops necessary to transfer packets between nodes, which in turn reduces network congestion and improves stability.


  1. Higher speeds will enable data transfer at twice the rate while improving spectral and energy efficiency and enable new higher throughput applications such as audio. Transferring large amounts of data, for instance in medical, sports and fitness applications, will also be much faster providing a better overall user experience. When combined with data length extension in Bluetooth 4.2, which is already supported on CC2640 devices, higher speeds from Bluetooth 5 will provide 500 percent increased data throughput over Bluetooth 4.0. Today, TI’s CC2640 wireless MCU supports up to 5Mbps communication.


  1. Increased broadcasting capacity will allow beacons to transmit richer and more intelligent data to enable effortless and seamless location and navigation services.

With these changes Bluetooth become a lot stronger and TI already offers a low power wireless MCU to start with. Though new smart phones and tablets should adopt to this new Bluetooth 5, but that should be only a matter of time.

Further information about Bluetooth 5 can be found here.

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