Radio location demystified

Radio Location Demystified

It comes as a surprise to many that indoor location is a core feature of reelyActive. “Isn’t that a solved problem?” The short answer is no. A sufficiently accurate, low-energy (battery-friendly) solution that makes use of an existing, ubiquitous infrastructure simply does not exist today. The intent of this blog post is to familiarize the reader with the basic mechanics of radio location to better understand the inherent challenges, and to clarify the reelyActive approach.

Listen or Speak?

Imagine you suddenly find yourself in an unknown place and it’s pitch black. You can’t see where you are, but it’s important that you find out. Consider the following two options:

  1. you listen to decipher your location based on the unique sound environment
  2. you shout out your name hoping that someone is listening, understands and locates you

Essentially, these represent the two common and fundamentally different options in indoor location. Do you expend a lot of energy listening? Do you simply shout out your name and hope someone else figures it out? In either case, your chances are best only when there are a lot of sounds or people listening nearby.

Listen Smart Devices

The smart device is well suited to the listening model. It hears WiFi routers and cell towers in range (indoors, it struggles to hear GPS satellites, so we’ll exclude this technology from the discussion). Since routers and towers are uniquely identifiable, by knowing their fixed locations, it’s possible to estimate the device location based on their signal strength and identity.

Information about radio infrastructure location and identity, being subject to continuous update, is centrally stored in the cloud. So the smart device must tell the cloud what it hears before its location can be determined. If the cloud responds to the smart device, then both know the current location and the device is said to be “location aware”. See the diagram on the left below.

Radio Location: Listen vs. Speak

Speak RFID

Active Radio Frequency IDentification (Active RFID) devices are well suited to the speaking model. Active RFID devices transmit their unique identifier periodically and rely on nearby infrastructure to estimate their location. As long as there are infrastructure nodes that hear the transmission, given their fixed locations, it’s possible to estimate the location based on the strength of the signal received at each. Assuming that the infrastructure nodes are Internet-connected, the cloud may calculate the location of the identifying device, which, in this case, is not location aware. See the diagram on the right above.

Listen vs. Speak

Today, neither approach is perfect. Here’s how the advantages play out:

  • the listen approach enjoys far greater infrastructure prevalence (WiFi and cellular)
  • the listen approach empowers the device user and service provider with location information
  • the speak approach is far better suited to inexpensive, low-power devices
  • the speak approach requires fewer, shorter radio transmissions in a single direction
  • the speak approach also empowers the infrastructure provider with location information

The speak approach currently suffers from a major shortcoming: the lack of an accepted global standard for low-power radio communication. Standards such as Bluetooth Low Energy, ZigBee and Low-Power WiFi have yet to cross the critical adoption threshold.

Regardless of approach, the accuracy of any location estimate is generally proportional to the number of infrastructure nodes in range and their proximity, and is represented as coordinates or as a pinpoint on a map.

The reelyActive Radio Location Approach

We favour the speak approach, overcoming its current disadvantages by creating an accessible infrastructure that supports both current and emerging low-power wireless standards. The location information in our cloud may be consumed by anyone or anything anywhere with the appropriate access rights.

However, unlike most systems which rely on triangulation to locate based on coordinates, reelyActive is instead about semantic location at points of interest. This is achieved by simply installing a cost-effective reelceiver at each point of interest and providing a meaningful semantic label. As a result, for any device which can actively transmit its identity, location would be available via our API as in the following examples:

  • IV pump #4 is in room 303
  • Carmen’s car just entered parking space #78
  • Sam’s smartphone is standing in front of the pasta sauce display
  • The temperature of the fish in loading bay 3 is 4°C


Pending the ubiquitous deployment of an appropriate radio infrastructure, indoor location will continue to be a hotbed of innovation. While the technique of listening and identifying the radio signature of an environment is prevalent and provides reasonable accuracy for smart devices today, the growing number of low-power connected devices of the Internet of Things will instead require an infrastructure that identifies, senses and locates by itself listening to those devices.

Limited Edition Artisanal Hub

Limited Edition Artisinal Hub

Disclaimer: this is a sillyActive blog post and, although the featured hub is in fact real (it was our first prototype back in January 2012) nothing else in the post should be taken seriously in any way. Enjoy!

Today we are proud to unveil our limited edition artisanal reelyActive hub. The product of countless months of intensive research and development, this hub represents the cutting edge in not only reel-to-Ethernet connectivity, but also DC transmission line power injection.

Connaisseurs will appreciate the raw beauty of the solid oak base. Hand cut and unfinished, it symbolizes the natural quality of this product. The wood pairs beautifully with the stainless steel of the two meticulously selected hose clamps, each coupling an active design element in delicate balance.

The hub’s energy resonates from a vintage Atari AC/DC converter. Just as audiophiles appreciate the subtleties of power supply construction, we have spared no expense in selecting the finest examples from the late nineteen-seventies, long recognized as the golden age of 12VDC converters. A generous length of cable ensures enough reach for the hub to be showcased as the centrepiece of any modern room.

The design is brought to life by the GW215 RS-422-to-Ethernet serial device server. Its gently blinking LEDs remind that this is a fully functioning piece of art. Housed in a full-metal enclosure, and featuring exposed terminal blocks, it brings an industrial intensity to the design, in juxtaposition with the recreational air of the Atari power supply.

Finally, reel connectivity is provided with the ultimate evolution in twisted pair cable design. Building on the foundations of Denon’s revolutionary AKDL1, our Cat5e pairs are hand twisted in perfect balance by master craftsmen. Exotic, noise-suppressing tie-wraps secure the cable to the harness at carefully selected locations. Each pair is then routed to the corresponding terminal block following a geometrically-optimal curve radius.

The result is an unmatched example of form, function and art. A must for any serious IoT or RTLS collector. Reserve your limited edition artisanal hub today as quantities are limited!

Interaction Design, the Superhuman and the Superorganism

Interaction Design, the Superhuman and the Superorganism

At reelyActive, we’ve often poked fun at the smart device (see our previous blog post). It allows us to do amazing things like communicate and share voice, images, videos and data across the globe. You could easily argue that it makes us superhuman communicators. But when you see someone standing frozen in the middle of a busy street, awkwardly buried in their smart device, oblivious to the “meatspace” in which they live, these superpowers are just as easily questioned.

Enter Interaction Design, or IxD, which is about “shaping digital things for people’s use” (thanks Wikipedia). A few months ago, we discovered a great documentary called Connecting, which explores the future of this field. Astute viewers will recognize from the font that this is a Microsoft ‘n pals endeavour, hence the exclusion of some other devices you might expect. Regardless, it’s totally worth 18 minutes of your time.

The Internet of Things features prominently (7:40), with Jonas Löwgren of Malmö University presenting the value of “more of the physical world connected with the digital world”. In other words, the IoT provides our digital world with context about what is really physically happening. And context allows for adaptation and better decision making. He sees the IoT as 5-7 years out.

It goes beyond Things. Andrei Herasimchuk of Twitter explains (11:53) how “people are now actually entering their lives into a digital format”. You could argue that humans are akin to complex sensors of the IoT, representing their experiences online. Twitter is the perfect example for real-time and historical thoughts. He feels, as do many, that we’ll be able to do exciting things in the future with those digital representations.

How does IxD help us become superhuman? In the video, you’ll see people interacting with far more than smart devices. Screens are everywhere. Gestures are recognized. Ambient information is presented to humans to provide context, and to allow for adaptation and better decision making. The physical-digital connection works both ways. Remember our friend frozen in the middle of the street? Amalgamated digital and physical context would allow him to receive the appropriate information at the appropriate time via the most appropriate channel. In other words, likely not on a 4″ screen in the middle of traffic.

But it’s not just about superhuman powers. Blaise Aguera y Arcas goes further to say (15:00) that as a by-product of this intense connectivity, “there’s a superorganism building up in which humans are no longer at the top of the food chain”. Depending on who controls the data and with what intent (see Big Brother and the Identity of Things), this may be a scary thought. But with an open IoT, just like the open Internet before it, this superorganism could instead become the most beautiful evolution of humanity. It’s an exciting time to connect the physical and the digital world.