Bluetooth Smart and IoT
Bluetooth is a global standard for low-power, low-cost, small-form-factor wireless tech which allows devices to connect and communicate over radio channels. The attach rate for Bluetooth is nearly 100% for all laptops tablets, and mobile phones and is gaining traction as a feature in headsets, speakers, printers, keyboards, etc. Bluetooth Low Energy (LE) is the most recent iteration to improve the Bluetooth Smart (4.0) specification. Bluetooth LE retains the functionality of Bluetooth Smart while extending the range, packet size, and energy conserving capabilities of the specification.
Bluetooth LE is on the forefront of IoT (the Internet of Things), swiftly becoming the language of choice for devices to communicate. Turning on a lightbulb wirelessly, receiving ETA alerts while in a hospital waiting room, or finding lost items (or meandering children)are all applications that can be realized easily with BLE technology.
Bluetooth LE is: Ad hoc, ultra-low power, small in size, low cost, short range, secure, and interoperable.
Bluetooth LE has applications in: IoT, Healthcare, Automation, Green Energy, Marketing, Mobile Payments, Telematics, and Security.
Bluetooth Smart (4.2) was released by Bluetooth SIG in December of 2014. Bluetooth SIG is a privately-held, NFP trade group. The Special Interest Group made Bluetooth smarter, faster and more capable of facilitating IoT scenarios. All Bluetooth Smart devices can be discovered, accessed, and controlled, via the Internet.
There are three ways in which Bluetooth Smart devices communicate with the Internet:
Bluetooth-enabled devices send intermittent signals, and these signals needed a bridge to the Internet. Nearly 100% of Smart Devices are capable of being that bridge. For when Smart Devices are not nearby to act as gateways, the SIG created standard RESTful APIs for Bluetooth GAP (Generic Access Profile) and GATT (Generic Attribute Profile). These APIs are within devices called gateways.
Another IoT bridge is called HTTP Proxy Service (HPS). The intermittent signals of a Bluetooth Smart Device can be relayed to a cloud server via HPS service in a router. An HPS Client such as a temperature gauge chirps messages containing packets of data to an HTTP Client which then posts the data to an HTTP Server.
IPv6 (over Low Power Wireless Personal Area Networks) is an Internet Protocol Support Profile (IPSP) which makes it possible for IP packets to be both sent and received by Bluetooth Smart Devices. Bluetooth Smart Devices such as a lightbulb receive packet instructions from a Bluetooth Smart Router controlled by a Smart Device. Bluetooth sensors can send and receive messages through gateway devices such as smartphones, tablets, and routers.
Bluetooth 4.0 and subsequent releases were a radical divergence from past specifications. Bluetooth Smart uses extremely short packets to maintain ultra-low power consumption. Bluetooth devices such as beacons can operate for years on a Lithium Coin battery. The more recent release of Bluetooth Low Energy (Bluetooth LE) has kept the ultra-low power consumption but expanded the size of packets by 10, allowing for greater quantity and quality of data transmission.
Bluetooth employs a Frequency Hopping Spread Spectrum (FHSS) mechanism to ensure nearby devices which emit radio waves do not interfere with data transmission. The hopping happens in a pseudo-random pattern which makes establishing a clear connection an immediate reality. f(k) = 2402 + k MHz, k = 0, …, 78 derives the frequency of the hopping. At 1600 hops per second across 79 radio frequency channels, data will get where it needs to be despite nearby interference. Bluetooth LE is able to ignore channels with interference through a feature called adaptive frequency hopping (AFH). When AFH is enabled, the Master device marks interference ridden channels as unused and removes these channels from the frequency hopping pattern. AFH can reduce the number of channels in use to 20, saving time and boosting efficiency.
Enhanced Power Efficiency
Bluetooth Low Energy (Bluetooth LE) has been optimized for power efficiency. Functionalities such as address resolution of remote devices has been moved to lower layers of the stack to save upper layers from involved activities. Since a BLE device is kept in sleep mode for much of the time, communications happen in a burst which saves on power consumption. A single coin battery can keep a Bluetooth Beacon in commission for years. For smart devices, battery drain is nearly negligible.
Bluetooth is the language of choice for IoT because it works everywhere and is compatible with nearly 100% of smart devices. The Bluetooth SIG is made up of 33, 462 companies and organizations (as of February, 2018). Membership is free to all companies hoping to develop products using the Bluetooth protocol. The SIG mandates that all devices undergo qualification before being marketed and launched for sale, ensuring compliance and interoperability. When a customer purchases a device with the Bluetooth logo, he or she can be confident that the purchased device will pair with other devices bearing the Bluetooth logo. In addition, Bluetooth uses a free radio frequency channel called ISM (Industrial, Scientific, and Medical). The free 2.4 GHz band does not require a license and functions perfectly globally.
Bluetooth Low Energy powers the devices we carry with us throughout our day. Bluetooth SIG developed features to ensure that our Bluetooth enabled mobile phones, running shoes, fitness bands, etc can not be used to track the user. A feature called Privacy 4.1 ensures addresses in a connection are scrambled so that eavesdroppers may not capture information. Random Address is another feature of Bluetooth LE which ensures third parties cannot access information. With Random Addresses, every time a Bluetooth device such as a fitness band transmits a message, it does so from a different address in a pseudo-random pattern. Bluetooth LE provides identity resolution keys (IRK) for paired devices to unscramble the real address of devices, letting intended devices receive data which they know originates from the same device despite arriving from a constantly changing string of random addresses.