When devices whisper to each other – Part 1: Intro

Hello Internet. Today I am starting a series of posts that will explain how devices whisper to each other. Er.. what does that mean? Well, when devices are within a few millimetres to single digits of metres of each other, they don’t need to shout out, do they? That’s why we are learning about a few communication protocols that are used when devices are near each other.

“But isn’t it better that devices are able to communicate from really far away? What’s the point if they just communicate when really close?” Bear with me, as I am going to give you some good reasons for why devices should communicate only when close to each other.

Why have close range communication?

Since Marconi developed the voice transmission radio in 1894, humanity has been fascinated with long distance communication. Telephones, television, satellite communication, mobile phones and the Internet have seen their share of limelight as the people are able to communicate with their loved ones in another hemisphere of earth. Astronauts and satellites are able to send communication back to earth. I am one of the biggest benefactors of remote communication, since I have established myself as a freelancer working from home, delivering software projects to clients in multiple cities.

This limelight has been at the expense of short distance communication, some of which is equally important. Let’s look at some wonderful use cases.

  1. Remote control appliances: You can control an electrical appliance from across the room without having to walk upto its panel to change settings. Think televisions, air conditioners and a media player such as Google Chromecast or Amazon Firestick.
  2. Voice control: Voice control is a form of short distance communication too. It is useful to make requests to voice activated devices such as Google Home or Amazon Echo.
  3. Wire free usage: Bluetooth speakers, wireless mice and wireless keyboards have made it possible for us to add peripherals to our computers / laptops / media players without having to get caught up in a tangle of wires around your desk or your house.
  4. Tap for payments: Now stop fiddling with your wallet to find change. In fact no need to fiddle with your phone’s home screen to open a payment app. Using technology such as tap-to-pay, tapping a credit card’s chip or a mobile phone’s NFC device on top of a specially designed payment terminal transfers money instantly or opens an app automatically to authorise payment.
  5. Share with those around you: Short range communication can be used to quickly share your favourite photos, videos and songs with those around you, without having to connect to a nearby WiFi or Internet.
  6. Get guidance in new places: Museums, railway stations, airports and bus terminals in experimental smart cities are using smart devices to send beacons from art exhibits, platforms, lounges and other pieces and places of interest. When you arrive close to an important museum exhibit, the beacon will send a URL to your phone based on which you can look for more information about that exhibit. Platforms, terminals, lounges and kiosks at transport hubs can send beacons to your phone to guide you to the right place.
  7. Track packages: RFC chips attached to packages send short bursts of communication to receivers placed at strategic locations during their shipment, say at the gate of dispatch facilities, inside the holding bay of transport trucks, at receiving and sorting facilities, etc.
  8. Never lose your keys: So far, we have seen how interesting things can happen when short range communication happens. But what about when communication stops happening? Take this example. A small transmitter attached to your important keys, such as car keys, home keys or locker keys keep sending beacons to your phone or to a small receiver sewn to your trouser / skirt pocket. When you forget your keys and wander a short distance away from them, your phone or your receiver beeps in panic and reminds you that you have forgotten something.

I believe that the above examples have convinced you that close range communication is as important as long distance communication. Special devices and phone applications are made all the time to harness the possibilities of communication between devices less than 10 metres from each other. In fact, the Internet of Things (IoT) is rife with applications, patents and proposals for devices which communicate with each other within short distances and then send data about such nearby communication to the Internet.

Protocols covered in the series

Here are the communication protocols we will cover in this series.

  1. Bluetooth Classic: We start the coverage of short distance communication with Bluetooth classic, that the world refers to as simply Bluetooth. I am making the distinction because of point 2.
  2. Bluetooth Smart: While the versions of Bluetooth from 1.0 to 3.0 are called Bluetooth Classic, a new version of Bluetooth, different from the classic version, was introduced in 2010, with the idea of operating bluetooth on tiny devices powered by batteries that power wrist watches. Bluetooth 4.0 through 5.1 are called Bluetooth Smart or Bluetooth Low Energy.
  3. Near-field communication (NFC): While the idea behind NFC was to use phones or electronic devices as wallets to pay at payment terminals by tapping, other ideas such as tapping to share files, media and contacts have also been showcased. The word ‘tap’ is not to be taken literally. You do not want to be smashing your precious phone against receiving devices. The ‘tapping’ refers to bringing your phone to within 2 – 3 cm of the target, so close that it feels like a tap.
  4. Zigbee: While not as popular as Bluetooth, NFC or even WiFi, Zigbee was started as an open standard protocol to enable home automation, wherein appliances from your home will talk to each other and to controllers to co-ordinate among themselves. Zigbee was to be the driving force behind smart homes. However, the advent of WiFi, which uses the same language (Ethernet, Internet Protocol and IP addresses) as the Internet itself, made it possible to make Internet-driven smart homes without having to inter-convert signals between Ethernet and Zigbee.
    But Zigbee still offers some advantages over using WiFi for home automation. So we will look at Zigbee in this series.

We won’t look at IrDA that uses infrared communication. This protocol is outdated. Likewise, we won’t look at methods like Walkie-Talkie, which is still in use, but only supports voice communication and is not suitable for data transfer or automation.


Despite all the advances in remote communication, such that we can now talk to satellites in outer space, there are still use cases and a growing need for devices to speak to each other even if they are just 3 centimetres away. We are going to study how such close range communication works and what protocols are the industry standards.


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