Advantages And Disadvantages

Bluetooth has a lot to offer with an increasingly difficult market place. Bluetooth helps to bring with it the promise of freedom from the cables and simplicity in networking that has yet to be matched by LAN (Local Area Network).

In the key marketplace, of wireless and handheld devices, the closest competitor to Bluetooth is infrared. Infrared holds many key features, although the line of sight it provides doesn't go through walls or through obstacles like that of the Bluetooth technology.




Unlike infrared, Bluetooth isn't a line of sight and it provides ranges of up to 100 meters. Bluetooth is also low power and low processing with an overhead protocol. What this means, is that it's ideal for integration into small battery powered devices. To put it short, the applications with Bluetooth are virtually endless.

Disadvantages
Bluetooth has several positive features and one would be extremely hard pressed to find downsides when given the current competition. The only real downsides are the data rate and security. Infrared can have data rates of up to 4 MBps, which provides very fast rates for data transfer, while Bluetooth only offers 1 MBps.

For this very reason, infrared has yet to be dispensed with completely and is considered by many to be the complimentary technology to that of Bluetooth. Infrared has inherent security due to its line of sight.

The greater range and radio frequency (RF) of Bluetooth make it much more open to interception and attack. For this reason, security is a very key aspect to the Bluetooth specification.

Although there are very few disadvantages, Bluetooth still remains the best for short range wireless technology. Those who have tried it love it, and they know for a fact that Bluetooth will be around for years to come.

How Bluetooth Works

Bluetooth devices will normally operate at 2.4 GHZ in the license free, globally available ISM radio band. The advantage to this band includes worldwide availability and compatibility. A disadvantage to this however, is that the devices must share this band with other RF emitters. This includes automobile security systems, other wireless devices, and other noise sources, such as microwaves.



To overcome this challenge, Bluetooth employs a fast frequency hopping scheme and therefore uses shorter packets than other standards within the ISM band. This scheme helps to make Bluetooth communication more robust and more secure.

Frequency hopping
Frequency hopping is basically jumping from frequency to frequency within the ISM radio band. After a bluetooth device sends or receives a packet, it and the device (or devices) it's communicating with hop to another frequency before the next packet is sent. This scheme offers three advantages:

1. Allows Bluetooth devices to use the entirety of the available ISM band, while never transmitting from a fixed frequency for more than a short period of time. This helps insure that Bluetooth conforms to the ISM restrictions on the transmission quantity per frequency.
2. Ensures that any interference won't last long. Any packet that doesn't arrive safely to its destination can be resent to the next frequency.
3. Provides a base level of security as it's very hard for an eavesdropping device to predict which frequency the Bluetooth devices will use next.
   

The connected devices however, must agree upon the frequency they will use next. The specification in Bluetooth ensures this in two ways. First, it defines a master and slave type relationship between bluetooth devices. Next, it specifies an algorithm that uses device specific information when calculating the frequency hop sequences.

A Bluetooth device that operates in master mode can communicate with up to seven devices that are set in slave mode. To each of the slaves, the master Bluetooth device will send its own unique address and the value of its own internal clock. The information sent is then used to calculate the frequency hop sequences.

Because the master device and each of the slave devices use the same algorithm with the same initial input, the connected devices will always arrive together at the next frequency that they have agreed upon.

As a replacement for cable technology, it's no wonder that Bluetooth devices are usually battery powered, such as wireless mice and battery powered cell phones. To conserve the power, most devices operate in low power. This helps to give Bluetooth devices a range of around 5 - 10 meters.

This range is far enough for wireless communication but close enough to avoid drawing too much power from the power source of the device.

Bluetooth In Action

In the United States, Bluetooth gets absolutely no respect. It is however, becoming more and morecommon in notebooks, PDAs, and especially cellphones. Bluetooth will provide wireless users a way to transmit small amounts of data over short distances.



Now, Bluetooth is facing stiff competition from new wireless technology. Referred to as UWB or
Ultra Wideband, it promises data transfer of up to 480 MB a second - while most current Bluetooth devices transfer data up to 721 KB a second.

For the time being, Bluetooth devices are surely cropping up. Below, we will look at some of the accessories offered with Bluetooth technology.

Talking to the dashboard
When pairing it with a cell phone, the CCM Blue Warrior car kit becomes a great speaker phone that plugs into the power adapter of your vehicle. The noise cancelling microphone will reduce background noise efficiently, with the large buttons making adjusting the speaker volume a snap. Although the Blue Warrior is far from sexy or sleek, it's very practical.

Tiny tuning box
Part MP3 player and part hands free phone, the compact and lightweight Sony HBM-30 is an attractive gadget that lets you accept calls with minimal interruption of your tunes. When you get an incoming call it will automatically pause your music, then you speak into the built in microphone that you can wear around your neck or clip to your clothes.

The pen
With Nokia's SU-1B digital pen, you can doodle and make hand written notes in ink on a special pad then transmit them from the pad to your Bluetooth phone. Being an alternative to typing on a cell phone keypad, the pen is very handy, although a pricey tool from MMS fans.

Snapshots
If you want to make slide shows with your camera photos, the Nokia SU-2 image viewer will let you disply your pictures on a TV or projector. Simply hook this square gray device to your TV's input with the built in cable, then beam the pictures to the SU-2 from your Bluetooth enabled phone and the photo fest will begin.

This device is a snap to set up and use, although it displays resolutions of up to 640 by 480. If
you have a newer phone that takes high resolution photos, you won't be able to use the Nokia SU-2 image viewer.

Keep in mind, the 640 by 480 pixel photos will appear blocky on TV screens, no matter what you do. If your phone can send batches of photos, you can create a slide show - although Nokia claims you can use sequentially beamed shots as well.

Bluetooth And Apple

The new Apple powerbook G4 are among the first computers to offer Bluetooth technology 2.0+EDR. The 2.0+EDR technology, which still backwards compatible with 1.0, is up to three times faster than previous versions, offering maximum data rate transfers of up to 3 MBps. Being the first company to certify a system with 2.0+EDR, Apple continues to make great use of the Bluetooth technology.


Full support
In addition to the powerbook G4 portables, there are other Bluetooth enabled computers available from Apple, including the iBook, iMac G5, eMac, and the Power Mac G5.

Making life easier
When you turn the Bluetooth feature on, your Mac can easily perform a file transfer or even a
synchronization. From the Bluetooth selection menu, you can choose to either send a file or
browse devices, quickly and easily. Or, you can click the sync button in iSync to update your
cell phone or Palm OS handheld.

The Mac and GSM/GPRS mobile phone with Bluetooth work to make each other more useful. By using iSync, you can keep your phone updated without having to type any info, as you can keep the information in the more manageable address book on your Mac instead.

You can also use your Bluetooth enabled Mac to print documents and digital images to select a
printer that also supports the technology of Bluetooth. Or, you can also use a headset to talk to your friends during an iChat session.

Your Mac also has the ability to use Bluetooth technology to communicate with your Palm OS
handheld. This way, you can perform a HotSync operation without using any cables. You can also send your business card or calendar events directly to someone else's handheld usingthe technology of Bluetooth.

The implementation of Bluetooth by Apple is the latest in a series of moves that have caused
great shift in the computer industry. Apple established USB as the standard interface with the launching of the first Mac back in 1998.

Since then, Apple established the 802.11 wireless standard of networking with the launch of the
iBook and AirPort in 1999. During 2003, Apple launched AirPort Extreme, which was based on
the new 802.11g high speed technology of wireless.

Now, Bluetooth helps to further strengthen the dominant position of the Mac in wireless
communications, helping to preserve Apple's reputation for being the first to market with
innovative technology that integrates right into the operating system.

Bluetooth Technical Operations

Bluetooth is a high speed, low powered wireless link technology that's designed to connect phones or other portable equipment together with little to no work required by the user. Unlike infrared, Bluetooth doesn't require line of site positioning to work.

Current prototype circuits are contained on a board that is 0.9 cm square, with a much smaller circuit board being developed.

When one Bluetooth device comes in contact with another, they will automatically exchange addresses and details of capability. Then, they can establish a 1 MB link with security that they will use as required. The protocols involved with handle both data and voice, with a very flexible topography.

The technology achieves its goal by embedding tiny, non expensive short range tranceivers into the devices available today. The radio operates on the 2.45 GHz frequency band, and supports up to 721 KBps, along with three voice channels.

Each devices offers a unique 48 bit address from the IEEE 802 standard, with the connections being point to point or multipoint. The max range is 10 meters, although it can be extended to 100 meters by increasing the power. The devices are also protected from radio interference by changing their frequencies, also known as frequency hopping.

What's important, is the fact that Bluetooth devices won't drain battery life. The specification
targets power consumption of the device, limiting the drain on the battery. The radio chip will
consume only 0.3mA in stand by mode, which is less than 5% of the power that standard phones use.

Bluetooth will also guarantee security at the bit level. The authentification is controlled by the
user via a 128 bit key. The radio signals can be coded with anything up to 128 bit. With the
frequency hopping, Bluetooth is already very hard to listen into.

The baseband protocol is a combination of both circuit and packet switches. Slots can be reserved for synchronous packets as well. Each packet will be transmitted in a different hop frequency. Normally, a packet covers a single slot although it can be extended to cover up to five slots.

Bluetooth can also support data channels of up to three simultaneous voice channels. Therefore,
it's possible to transfer the data while you talk at the same time. Each individual voice channel
will support 64 KB.

From a technical standpoint, Bluetooth is very different indeed. It's the best wireless method
in the world, surpassing even infrared. For communication on the go, Bluetooth is indeed very hard to compete with.