Bluetooth Low Energy (BLE) and the Internet of Things (IoT)

The speculation over the Internet of Things (IoT) phenomenon has been gaining grounds in recent years, and there seem to be no signs of it slowing down anytime soon. Despite all the headlines and hype, it is fair to say most people are still in the dark as to what the impact of this soon to be mainstream technological sensation will be. In all honesty, IoT has been around for some time now. However, it will soon become a part of life that people take for granted. Let’s examine what IoT is, and the role Bluetooth Low Energy (BLE) plays in its development.

What is Bluetooth Low Energy?

For a novice, it is simple to see BLE as a type of Bluetooth that uses less power, consumption or energy. It is an eco-friendly form of Bluetooth that has been developed specifically to facilitate the “Internet of Things”. I guess by now almost every soul on the planet is familiar with what Bluetooth is, right? Anyways, to shed more light; think of using a wireless headset to listen to your favorite song on your smartphone. Yes, that is an application of Bluetooth.

However, a new wave of technological advancement is on the horizon known as the Internet of Things or for short (IoT). This next wave of mainstream tech will enable the connectivity of your everyday household devices (like the washing machine, cooker, toaster, kettles, etc.) to one another and to the internet. These devices will be able to communicate with you directly or be controlled by a smart device such as your smartphone or tablet. Yes, that’s right! You won’t need to border about turning “on” or “off” the washing machine or heating the kettle manually as these would be possible just by the touch of a button on your smartphone. How cool is that?

So, what is the Internet of Things?

In short, the Internet of Things is the connection of a device to other devices (usually through some form of wireless connectivity such as Bluetooth low energy) and to the Internet to help them communicate and share data across wireless networks. Therefore, IoT is a humongous connection of “things” which also includes people, animals and basically whatever you choose to connect. Bluetooth chips can be used to make animals part of the internet of things, as some people do with their pets already. So, the connection could be between people-to-things, people-to-people, people-to-animals, things-to-things, things-to-animals, etc… you get the point, the possibility is endless!

The “Internet of Things” is not limited to within the house; it extends to the workplace, cars and even entire cities. It is extraordinarily huge. The scale at which it will change the way we live and work is yet to be determined. For example, in cities think about the connection of traffic lights and security cameras to share data with security offices. Through IoT, our devices will be able to communicate to us by voice or text just like our smartphones and computing devices do today (e.g. Cortana, Siri, Google Now). Our energy meters will tell us when to turn them off; our cars will tell us to stop driving if they’re tired of being driven without being serviced properly. Okay, might be a bit exaggerated! But who knows? The limit to your imagination is your only limitation with the Internet of Things.

But what is the role of BLE in IoT?

BLE’s energy efficiency has made it a preferred and and one of the most compatible options for IoT. BLE, for example, is more energy efficient than ZigBee, Bluetooth classic and Wi-Fi. What this means is that BLE can better support the connectivity of IoT devices for longer periods than the above (especially when the devices are battery-powered). Also, BLE’s low data rate makes it extremely suitable for utilization in cases where only state data has to be exchanged such as sensors. It is also the dominant low power technology in smartphones these days, unlike ZigBee, Z-Wave, LoRa and others.

Applications

BLE (Bluetooth low energy) was introduced by the Bluetooth SIG in the 4.0 spec of Bluetooth. As the name suggests, BLE focuses on low energy consumption. Low energy focus comes with some sacrifices particularly around data transfer rates and the range of operation. But that’s not a bad thing, in fact BLE is very suitable for many applications. With all the hype around IoT (Internet of Things) and the slew of technologies and devices out in the market, BLE is attempting to position itself as a leader for the future of IoT. Some of the many suitable applications for BLE are:

• Fitness trackers (such as Fitbit, Misfit..etc)
• Smartwatches (such as the Apple Watch, Moto 360, and Pebble)
• Beacons (Apple iBeacon, Google Eddystone)
• Medical devices such as glucose meters, insulin pumps
• Home automation devices such as door locks, light bulbs, sensors, and others

Advantages

• Low power consumption
• Low bandwidth – perfect for collecting data from sensor devices
• Proliferation in smartphones
• Relatively simple development process
• No fees to access the core spec
• Low development and module costs
• No outrageous licensing costs compared to other low power wireless technologies

Disadvantages

Every technology has its disadvantages and BLE is no exception. The main ones are:

• Low bandwidth – not suitable for large data transfer applications
• Limited range (typically 30 -100 m, but steadily increasing with each iteration of the spec)
• Requires a gateway device to connect the end devices to the Internet (smartphones, dedicated gateway devices)
• Interference and noise from other protocols in the 2.4 GHz spectrum (WiFi, Bluetooth classic, ZigBee..etc)
• Can be difficult to debug issues with communications especially relating to longer ranges and interference
• A bit of a learning curve for newcomers to the technology

Types of Bluetooth devices

There are 4 types of Bluetooth devices in regards to support for low energy and classic:

• Bluetooth devices implementing a pre-4.0 spec -> do not support BLE
• Bluetooth devices implementing both the classic and low energy features. Typically smartphones, PCs, tablets..etc (formerly known as Bluetooth Smart Ready devices)
• Bluetooth devices implementing only the low energy features – sensor devices, and others typically running on batteries. Examples include smartwatches, fitness trackers, beacons…etc (formerly known as Bluetooth Smart devices)
• Bluetooth devices implementing only the classic features. Think headsets, wireless speakers, car infotainment systems..etc

Architecture of a BLE device

There are three main software levels in the architecture of a BLE device:

• Application: the application interfacing with the stack and implementing the specific user applications
• Host: high level layer of the protocol stack.
• Controller: low level layer of the protocol stack including the physical layer

Modes of operation

HCI (Host Controller Interface) is a standard communications protocol defined by the Bluetooth SIG to allow developers to use multiple processors from different vendors (one as a radio device, and another as the main processor for implementing the application).

Two main modes in BLE:

• Broadcasting: a broadcaster device initially advertises its presence and an observer device will discover these broadcasters by scanning the surroundings. Some devices stay in this phase, such as Apple iBeacons and Google Eddystone devices. This allows the broadcasting device to make itself visible to any observer and advertise a limited amount of useful info.
• Connection: starts with a device advertising (Peripheral/Slave) and another (Central/Master) scanning the specific advertising channels. The connection is then initiated by the central device. This mode connects the two devices allowing data transfer and a private communications channel between the two (this is the typical case outside of beacon devices). Once a connection is established, the end device (the embedded device) can turn off the radio leading to a lower power consumption.

Profiles

• Generic profiles: these are the generic profiles defined by the Bluetooth spec. They lay out the fundamentals for all BLE devices.
• GATT (Generic Attribute Profile): a basic data model that allows devices to discover, write, and read elements.
• GAP (Generic Access Profile): layer responsible for managing connections, advertisements, discovery and security features.
• Use-case profiles: Adopted by the Bluetooth SIG and defining common behavior to make implementation simple for specific use-cases. Examples: Glucose profile, Heart Rate Monitor profile, Proximity profile.

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