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What is Bluetooth?

Posted on 10-Jan-2003 08:05 by M Freitas | Filed under: Articles

What is Bluetooth?
Think of Bluetooth as a cable replacement. It’s a personal technology created to connect multiple personal devices, in a small Personal Area Network.

The idea is to have a technology cheap enough and low power consumption, easy to implement in different devices.

Bluetooth is radio-based, using the unlicensed 2.4 GHz radio spectrum. Up to seven simultaneous connections can be established and maintained. Although it uses the same frequency as Wi-Fi (802.11b) it is not conflicting with this wireless network technology, because Bluetooth uses frequency hop, changing frequency 1600 times a second.

What Bluetooth can do for me?
Bluetooth allows the creation of “islands” of information for you. Your devices can talk to each other and share services. Examples of devices available are mobile phones, printers, USB dongles, headsets, car kits, digital cameras, Palm devices, Pocket PCs, Access Points, and others.

These devices will share information or resources in between them.

How do I use Bluetooth?
Each device implements different profiles. It can have one or more of these. Each profile determines one resource or information your device is able to share.

A headset will have the “Headset” serve profile, while a mobile phone will have the “Headset” client profile, plus “Business Card” exchange server and client profiles. The mobile phone may also have the “Dial Up Networking” server profile, the “Serial” server profile and the “Fax” server profile.

Your notebook or desktop can have all these profiles, in both server and client versions. Your printer can have the “Print” server profile.

You “introduce” one device to each other. This introduction is called “pairing”. Paired devices will be authorised to use selected “profiles” between them. After a device is paired, you don’t need to repeat the process.

Give me an example!
We’ll talk in generic terms, since each device has different menus and ways of doing it. In my case I have the following:

  • Mobile phone with GPRS and data account enabled
  • Desktop
  • Headset
  • Pocket PC

  • First let’s pair the Pocket PC and mobile phone. After this step is completed, you can select the “Make this my Dial Up device” option in your Pocket PC. From now on, every time you want to access the Internet on the go, just turn your Pocket PC on and start your application. It’ll automatically connect to your mobile and instruct it to dial up to your provider, or connect to the GPRS network.

    After our surfing session we pair the headset with the mobile phone. From now on, if a new call comes in, it will ring both the mobile and headset. Put the headset on, press the button and you’re talking, without cables! And your mobile can be in your pocket, in your briefcase, anywhere within the Bluetooth range.

    Great, but I want to synchronize my Outlook Contacts with my phone. Yes, you can do it. Mobile makers supply the software to sync this information. Pair your mobile and notebook or desktop. Select the “Serial” services and use the software. Your contacts will “fly” from your computer to your phone. Change the information in one side, and it will change in the other, on the next sync! And if your Pocket PC is connected to your computer, via Bluetooth or USB, the information will be updated there too!

    Can I use the headset with my computer? Yes! Depending on the USB dongle you use in your computer, you may have the headset profile client there. Just pair the headset and computer and you can have a cordless headset, to listen your favourite MP3 around the house.

    All good… But can I share my fast home Internet access with my Pocket PC? If your device has the appropriate profile, yes. When you install your Bluetooth device in your computer it will create a “virtual” Ethernet adapter. Just use Internet Connection Sharing and connect to this profile from your Pocket PC. Of course the speed is not great, but you can surf, check e-mails, have ICQ up and running, while away from your desktop.

    We didn’t talk about file exchange, business card exchange, appointments, notes, etc… There are lots of profiles and each device will use it in a different way.

    This is a short list of Bluetooth profiles:

  • SPP – Serial Port Profile used for serial port emulation
  • GAP – Generic Access Profile used link management and device discovery
  • GOEP – Generic Object Exchange Profile used for object push, transferring files, and synchronization
  • SDAP – Service Discovery Application Profile used for information and service discovery
  • SP - Synchronization Profile
  • FP - Fax Profile
  • FTP - File Transfer Profile
  • OPP - Object Push Profile for sending data objects between devices (e.g. business cards)
  • HS - Headset Profile (e.g. headset and cell phone connections)
  • DNP or DUN - Dial-up Networking Profile for modems, mobile phones (e.g. Access your ISP using Pocket PC and cell phone)
  • IP - Intercom Profile for speaker phone type of functionality
  • LAP - LAN Access Profile (e.g. A low bandwidth method for accessing a LAN)
  • CTP - Cordless Telephone Profile (e.g. handset to base telephone connections)

  • And these are the main characteristics of a Bluetooth implementation:

  • wire and cable replacement technology
  • short range – typically up to 10m
  • low bandwidth - around 720kbps max
  • low component cost – less than $20 US
  • low power – 0.3 mA standby and 30 mA maximum during data transfer
  • 2.45 GHZ ISM does not require licence
  • limited interference issues - Spread Spectrum Frequency hopping and very fast hopping between the 1-MHz bands (1,600 times/sec)
  • secure with built in encryption