With Bluetooth, you can place gadgets wherever you want, and finally have a clean office desk. But perhaps more importantly, Bluetooth saves time and improves mobility by supporting a portable network anywhere. You do not have to stop, sit down, and mess with the cables in order to use your electronics. This portable personal network is typically anchored in a smartphone or laptop computer. To fully understand the power of Bluetooth, let's first check out some common use cases for the Bluetooth technology.
Supported by almost all electronics and computer vendors, Bluetooth can be found everywhere. The following is just a partial list of uses of Bluetooth today.
Wireless headsets: Perhaps the most widely used Bluetooth devices are the wireless headsets of mobile phones. Using these headsets, you can talk on the phone while in motion (e.g., while walking or running), without the hassle of wires. New Bluetooth headsets can be so small that they can be embedded into a pair of sunglasses. In addition to mobile phones, there are also Bluetooth headsets and speakers for portable music players like the iPod.
Car kits: A natural extension of the Bluetooth headset is the hands-free car kit. A Bluetooth car kit allows you to use your voice to operate the phone, and talk on the phone via the car's built-in audio system. They can also display caller IDs, caller pictures, and other call information in the dash. You never need to plug the phone into the car, which would require different connectors for different phones.
Keyboards and mice: Common computer accessories like keyboards and mice can be connected to the PC via Bluetooth. This helps to keep the office desk tidy. But more importantly, some Bluetooth keyboards and mice also work with smartphones and PDAs. They are essential tools for mobile email.
Device synchronization: Old PDAs synchronize their contact lists, calendars, and email with computers via bulky cradles. The newer generation of smartphones (and PDA phones) support synchronization via Bluetooth. If you carry multiple devices on the road, you'd probably appreciate the elimination of the cradle.
Wireless access points: Bluetooth can provide connectivity from devices to an internet access point. For instance, you can share a wireless internet connection from a mobile phone to a laptop via Bluetooth. This way, you can use your laptop to browse the internet whenever your phone has a signal. Compared with regular WiFi, the wireless internet via the mobile phone network (i.e., the GPRS/UTMS/EV-DO networks) is more pervasive, cheaper, and often faster.
Printing: With a Bluetooth-enabled printer, you can print photos or documents directly from a digital camera, a camera phone, or a laptop. This type of printer is ideal for field workers or busy professionals.
File transfer: Computers, including mini-computers like PDAs and smartphones, can send files to each other via Bluetooth connections. You can transfer photos from a camera phone to a computer, install smartphone applications from a computer, or exchange documents between laptops in a conference room.
Content provision: As mentioned earlier, Bluetooth can be used to provision photos, ringtones, and other multi-media contents to smartphones from computers. In fact, some retail stores have even installed Bluetooth booths to sell mobile-phone content to customers.
Handheld navigation: Bluetooth-enabled GPS receivers can be connected to PDAs, smartphones, or laptops. You can leave the GPS receiver in your pocket or backpack, and use the mapping software on the computer to navigate.
Remote control: Bluetooth smartphones or touch/type pads can be used as a remote control for computers (PCs and Macs). You can control PowerPoint presentations, media playback, or arbitrary applications on the computer. The smartphone screen displays information relevant to the task running on the computer. For instance, the remote control smartphone can display the current slide note during a PowerPoint presentation, or the album cover of the current MP3 song. Sony Ericsson has a free utility to turn any of their Bluetooth phones into a PC remote control. Similar software is also available for Nokia Series 40 and Series 60 smartphones.
Social networking: Bluetooth devices can discover and communicate with nearby devices. They can facilitate communications between strangers who happen to be in the proximity. Nokia Sensor is a free Bluetooth application for Series 60 smartphones. You can publish your personal profile, including photos, on your Bluetooth smartphone, and nearby Sensor users can then view your profile on their smartphones. You can also search for and view Sensor profiles nearby. If you find an interesting profile, you can message that person, or simply walk over to strike up a conversation.
There are many other use cases that I cannot cover in the limited space of this article. For any specific use case, it might seem that it is not a big deal to use a cable connection instead of a Bluetooth wireless connection. But if you have multiple devices that need to communicate with each other, the number of cables increases geometrically as the number of the devices does. Bluetooth becomes more and more important as we carry more and more personal gadgets. The Bluetooth solution is especially useful for smartphones, as most smartphones use non-standard and expensive data cables.
To take advantage of Bluetooth devices and applications, we need to learn a little about technology behind Bluetooth.
The Bluetooth network uses an unlicensed radio frequency at 2.45 GHz. It is the same frequency used by WiFi networks, cordless phones, and microwave ovens. A Bluetooth device typically has a range of ten meters (32 feet), and a data rate close to 300kbps. Since the 2.45GHz radio wave can penetrate walls, you can connect Bluetooth devices across rooms.
Bluetooth networks are ad hoc networks. A Bluetooth device automatically detects devices within its range and forms networks with them. If a device goes out of range, the network automatically drops its membership.
The details of the Bluetooth network topology and discovery protocols are not important for most users. You just need to know that once a Bluetooth device joins a network, it can "see" all devices in the network. And Bluetooth networks can connect to each other via bridge devices. For instance, in a very large conference hall, the localized Bluetooth networks (devices within a ten-meter radius) can join each other and form a big network that covers the entire hall (much larger than ten meters). When a device at one of the end of the hall communicates with a device at the other end, the traffic might be relayed via several bridge devices. Any Bluetooth device can become the bridge, and the device owner does not need to know whether his/her device is a bridge--it is all done transparently at the network level.
Most Bluetooth-enabled computers, PDAs, and smartphones support the basic serial communication profile. Potentially, Bluetooth applications on those devices can exchange arbitrary complex data via the serial port interface.
The Bluetooth specification defines not only low-level radio communication protocols, but also high-level content exchange protocols, known as profiles. Two Bluetooth devices supporting the same profile can exchange content with each other. For instance, a mobile phone and its wireless audio headset support the headset profile; Bluetooth digital cameras, including camera phones, and Bluetooth portable printers support the printing profile; PDAs, smartphones, and PCs support the synchronization profile for address book/calendar/to-do list/email synchronization; mobile phones supporting the dial-up network profile can be used as wireless modems for laptop computers; devices that exchanges file with each other, such as a smartphone, a PDA, a camera, and a PC, support the file transfer profile.
For your Bluetooth device, you can find its supported profiles, and how to set it up to work with other devices, in the owner's manual. You can also find out more information about Bluetooth profiles from this website.
As a network protocol uniting many different types of devices, Bluetooth is only useful when it enjoys wide industry support. In reality, Bluetooth is an industry standard supported by all major electronics and computer vendors. The industry-wide collaboration of Bluetooth is done through a forum called the Bluetooth Special Information Group (SIG). You can find Bluetooth specification documents and a list of Bluetooth devices on its website.
To use Bluetooth, you have to set up the devices and authenticate them with each other. The exact instructions, obviously, are different for each device, and you have to look them up in the device's manual. However, the same general principles apply. Below is a brief overview of the process.
By default, Bluetooth is turned off on most handheld devices in order to reduce power consumption.
For most Bluetooth-compatible handheld devices, such as smartphones or PDAs, you do not need to install additional hardware or software to enable Bluetooth. You just need to navigate to the connectivity configuration menu on the device UI, and turn on the Bluetooth radio. Once Bluetooth is on, you can typically see a Bluetooth symbol or a small black dot on the idle screen. The device also has built-in Bluetooth utility software for changing the device name, changing the discovery mode, authenticating with other devices, sending files/messages, etc.
For computers, setting up Bluetooth is a little more complex. You first need to make sure that there is Bluetooth hardware installed on the computer. If not, you can easily purchase a USB-based Bluetooth dongle and just plug it in. If you do not want the dongle to stick out of your computer or have no spare USB port, you can purchase a Bluetooth card that can be installed inside of the computer. Different operating systems provide different levels of support for Bluetooth hardware.
Mac OS X: If you use a late-model Mac computer with the Mac OS X operating system, you can simply open System Preferences and click on the Bluetooth icon to turn on Bluetooth. The Mac OS X system has built-in Bluetooth utilities to perform common network tasks (e.g., searching for nearby devices, transferring files). It is recommended that you leave the Bluetooth icon in the system menu bar so that you can easily access the Bluetooth features with one click of the mouse.
Windows before XP with SP2 (Service Pack 2): If your Windows computer has an operating system older than Windows XP with SP2, you have to install the driver software that comes with your Bluetooth dongle or card. The driver software comes with common utilities to configure the Bluetooth properties of the PC and communicate with other devices on the Bluetooth network.
Windows XP with SP2 and later: A major new feature in Windows XP SP2 is the built-in Bluetooth support. When you plug in the Bluetooth dongle, Windows prompts you to install new hardware and select the appropriate driver already bundled in the operating system. After the hardware is successfully installed, you will see a Bluetooth icon in the system icon tray. Click on that icon to access Bluetooth network utilities.
Linux: To make Bluetooth work on a Linux box, you have to make sure that you have a recent Linux kernel (2.4.22 or the 2.6 series). Then, you can install the BlueZ Bluetooth support package. However, as a command-line tool, BlueZ is not particularly user-friendly. You have to issue multiple complex commands to complete simple tasks like authenticating a peer device or transferring files. If you use the GNOME or KDE desktop systems, you can download the GNOME Bluetooth Subsystem or KDE Bluetooth Framework packages to add an easy-to-use GUI for Bluetooth network utilities.
Since the Bluetooth drivers in the operating system must support Bluetooth profiles, those drivers come with native utilities for communication tasks defined in the profiles, such as device authentication, business card/file transfer, PIM synchronization, and so on. Nokia Smartphone Hacks covers details on how to set up Bluetooth on Mac, Windows, and Linux computers to connect to a smartphone.
Due to the dynamic nature of Bluetooth networks, you can often find devices owned by total strangers joining your network in a crowded room. To ensure security and privacy, Bluetooth devices are typically required to authenticate with each other before they can exchange data. The simplest form of authentication is to ask for the user's explicit approval. For instance, if you send a business card or photo from one smartphone to another, the recipient device would prompt its owner to "accept the incoming data item" by explicitly acknowledging a pop-up alert box on the screen.
For long-running data exchanges, such as PIM synchronization, hands-free operation, and dial-up networking, we cannot require manual approval for each data item exchanged. Those operations also typically transfer sensitive data that need more protection than simple recipient acknowledgment. In those cases, we need to establish a trusted relationship between two Bluetooth devices by pairing them. You can initiate pairing from any device by selecting the "pair/set up new device" menu in the Bluetooth utility software. The initiating device searches for all Bluetooth devices nearby and ask you to select a recipient device from the search results. You will be promoted enter a random security code (i.e., a PIN) on the initiating device. The recipient device would then receive a pairing quest and prompt you for the security code you just entered on the initiating device. Once the security code is confirmed, the two devices are paired.
Security is an important issue in Bluetooth networks, given the ad hoc nature of network membership. The Bluetooth specification is designed with security in mind. You are required to authenticate or even pair devices for certain tasks. And communication data between paired devices can be encrypted. However, individual devices might still have weaknesses in their Bluetooth implementation, which would allow Bluetooth attacks ranging from harmless pranks to serious data theft or device-crippling viruses. Here are some typical Bluetooth attack scenarios:
Bluejacking: When you send a business card to a smartphone via Bluetooth, the recipient phone screen typically displays the card sender's name in an alert box. If a prankster creates an empty business card with a fake message in the "name" field (e.g., a prank message like "Your phone is hacked!"), he or she can make your phone appear as if it is malfunctioning.
Bluesnarling: Some Bluetooth devices have implementation bugs that allow other devices to establish trusted relationships (i.e., pairing) without user approval. Those attacks are serious, since the attacker can steal or overwrite your personal data on the device, make phone calls using your service account, or even spread virus programs.
Bluetooth viruses: Some mobile phone viruses spread via Bluetooth networks. They detect vulnerable devices nearby and install unauthorized virus programs on them for further spreading. Those viruses can cause damage to your device and your data.
To prevent Bluetooth attacks, you could turn off your Bluetooth radio or make your device invisible by turning off the discovery mode. You can also install anti-virus software or even use a Bluetooth firewall to filter out unwanted traffic.
Bluetooth evolved from a cable replacement technology for existing applications. It is now a ubiquitous personal area network technology enabling applications never possible in the cable world (e.g., social networking and remote control). The Bluetooth SIG is working with other standards bodies, including Ultra Wide Band (UWB) specification committees, to develop the next-generation Bluetooth technology. It could cover areas up to 100 meters, and have a data rate exceeding 100Mbps, making it suitable for streaming high-quality video contents in your home. The best of Bluetooth is still ahead of us.
Michael Juntao Yuan specializes in lightweight enterprise / web application, and end-to-end mobile application development.
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