Bluetooth Technology 101

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From keyboards to headsets to mobile computing, Bluetooth provides the personal wireless network needed to get around without a bunch of cables entangling our lives. Here's a close look at a key technology that empowers our mobile world.

Bluetooth Operation

Piconets

Bluetooth is designed for communication over a small network called a piconet. The simplest configuration is a point-to-point piconet, with one device designed as a "master" and the other a "slave." The master initiates the communication link, and in general, has control over the network's timing. Up to seven slaves can be connected to a master in a point-to-multipoint configuration. An example of this kind of operation is a smartphone (master) connecting to multiple Bluetooth slaves—a Bluetooth headset for streaming music, a Bluetooth keyboard as an input and a second smartphone for Bluetooth-based file transfers. This kind of system implies an ad-hoc network with no fixed roles or designations. Also, a Bluetooth master can dissolve its piconet and then go join a different piconet as a slave. Here's an example of Bluetooth network organization; Network 1 is a piconet in standalone mode, Network 2 is a scatternet:

A Bluetooth device can be a slave in more than one network (an example would be a multi-point Bluetooth headset that connects to a smartphone and a laptop simultaneously, and the data input from each source device switches the operation of the headset), or a slave in one network and a master in another. Configurations that go beyond the master-and-seven-slave setup are called scatternets.

Establishing A Bluetooth Piconet

Initiating a piconet is done by a master, and the Bluetooth protocol establishes a universal method for establishing links:

  1. INQUIRY: the master sends out an inquiry to determine which devices are in range
  2. INQUIRY RESPONSE: the devices hearing the inquiry respond with specific information (their paging parameters)
  3. PAGE: the master then pages the specific device it wants to connect to
  4. PAGE RESPONSE: the paged device acknowledges and responds
  5. LINK PARAMETER EXCHANGE: now the two devices exchange their link parameters, and bi-directional data transfer can begin.

Each Bluetooth device can be in a number of states, depending on the commands sent to it (either internal, or based upon the type/commands of received data packets over the radio) and the type of operation that is expected of it. The three overall states are "standby," "connection," and "park." Each device maintains its own state, and the master maintains a list of its slaves' states (or expected states). There are also a number of sub-states: page, page scan, inquiry, inquiry scan, master response, slave response and inquiry response. 

Gene Fabron
Gene Fabron is an Associate Contributing Writer for Tom's Hardware US. He writes reference material across a range of components.
16 Comments Comment from the forums
  • Faheemahmed125
    wow! all we need is bluetooth with hih range like wifi!!!
    Reply
  • Fernando_engen
    Bluetooth is pretty much the future. I have just started developing Bluetooth Low Energy Services/profiles for specific use cases along with the application layer. Its an awesome new world.
    Reply
  • YunFuriku
    Actually hearing aids with button cell batteries these days can use Bluetooth Smart or to be exact
    bastardized proprietary version of it by Apple and GN Resound which enables them to have wireless audio streaming from
    various devices with Bluetooth. Comes with expense of range naturally because hearing aids need to use low power version of it (1,5V doesn't give much choice on this )
    Max 10m in ideal conditions.
    Sadly, the audio stack they use is Apple Exclusive so direct connection is Apple devices only.
    Non-apple devices require intermediary devices such as TV streamer or Phone Clip to other Bluetooth Capable phones. These devices are relatively cheap compared
    to old FM tech hearing aids used to use where transmitter prices were measured in 0,5-2k range, about ~$200-300 at most.

    Unfortunate side is that if you want to use it with non-Apple phones you'll have to have intermediary device which serves as bluetooth handsfree mic/answer/volume
    buttons too beause of the audio stack which Apple won't license to others.
    At the same time Apple is pushing their made for iPhone hearing aid tech to FCC to be recognised as standard.
    Here's to hoping hardcore android fan like me won't have to buy iPhone as my next phone if this doesn't come to other phones directly because of silly audio stack :P
    Reply
  • RIluske
    Is the graphic about memberships correct? I thought the article said the third tier was free to join, but the graphic has it costing the same amount as second tier.
    Reply
  • zodiacfml
    I feel WiGig has a better future eventually. Bluetooth will be left to activation or turning on devices or IoT as already mentioned in the article.
    Reply
  • DotNetMaster777
    Very useful article !! bluesniping can be done over one km away wow !?!?


    Are there any performance tests between wifi and bluetooth ??
    Reply
  • exnemesis
    Just give me bluetooth tech that can allow me to walk away 40-50m from my phone and penetrate better through walls and objects and still retain the quality of whatever it is I'm listening to on my phone.
    Reply
  • TripleHeinz
    This is the best article I've ever read in Tom's. Didn't have a clue that bluetooth was related with Thor the god of thundervolt ;)
    Reply
  • Mpablo87
    Good))
    Reply
  • yasminpriya15
    Welcome to Bluetooth 101. Here are the top things you need to know about Bluetooth technology.

    My Bluetooth doesn’t work. What do I do?
    The Bluetooth SIG does not make, manufacture or build any Bluetooth products. We simply support our membership and help them to help make the best products on the market. The best way to solve your problem is to contact the manufacturer directly or start by researching solutions on the Internet.

    What is Bluetooth?
    Bluetooth is a global wireless communication standard that connects devices together over a certain distance. Think headset and phone, speaker and PC, basketball to smartphone and more. It is built into billions of products on the market today and connects the Internet of Things (IoT). If you haven’t heard of the IoT, go here.

    How does Bluetooth work?
    A Bluetooth device uses radio waves instead of wires or cables to connect to a phone or computer. A Bluetooth product, like a headset or watch, contains a tiny computer chip with a Bluetooth radio and software that makes it easy to connect. When two Bluetooth devices want to talk to each other, they need to pair. Communication between Bluetooth devices happens over short-range, ad hoc networks known as piconets. A piconet is a network of devices connected using Bluetooth technology. The network ranges from two to eight connected devices. When a network is established, one device takes the role of the master while all the other devices act as slaves. Piconets are established dynamically and automatically as Bluetooth devices enter and leave radio proximity. If you want a more technical explanation, you can read the core specification or visit the Wikipedia page for a deeper technical dive.

    Are there different kinds of Bluetooth?
    There are actually several “kinds”—different versions of the core specification—of Bluetooth. The most common today are Bluetooth BR/EDR (basic rate/enhanced data rate) and Bluetooth with low energy functionality. You will generally find BR/EDR in things like speakers and headsets while you will see Bluetooth Smart in the newest products on the market like fitness bands, beacons—small transmitters that send data over Bluletooth—and smart home devices.

    What can Bluetooth do?
    Bluetooth can wirelessly connect devices together. It can connect your headset to your phone, car or computer. It can connect your phone or computer to your speakers. Best of all? It can connect your lights, door locks, TV, shoes, basketballs, water bottles, toys—almost anything you can think of—to an app on your phone. Bluetooth takes it even further with connecting beacons to shoppers or travelers in airports or even attendees at sporting events. The future of Bluetooth is limited only to a developer’s imagination.

    What makes Bluetooth better than other technologies?
    The short answer is because Bluetooth is everywhere, it operates on low power, it is easy to use and it doesn’t cost a lot to use. Let’s explore these a bit more.

    Bluetooth is everywhere—you will find Bluetooth built into nearly every phone, laptop, desktop and tablet. This makes it so convenient to connect a keyboard, mouse, speakers or fitness band to your phone or computer.
    Bluetooth is low power—with the advent of Bluetooth Smart (BLE or Bluetooth low energy), developers were able to create smaller sensors that run off tiny coin-cell batteries for months, and in some cases, years. This is setting the stage for Bluetooth as a key component in the Internet of Things.
    Bluetooth is easy to use—for consumers, it really can’t get any easier. You go to settings, turn on your Bluetooth, hit the pairing button and wait for it start communicating. That’s it. From a development standpoint, creating a Bluetooth product starts with the core specification and then you layer profiles and services onto it. There are several tools that the SIG has to help developers.
    Bluetooth is low cost—you can add Bluetooth for a minimal cost. You will need to buy a module/system on chip (SoC)/etc. and pay an administrative fee to use the brand and license the technology. The administrative fee varies on the size of the company and there are programs to help startups. http://www.traininginsholinganallur.in/qtp-training-in-chennai.html
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    Reply