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Bluetooth Wireless Networking Explained

Part 1 of a series on Bluetooth

Please also see How to Choose a Bluetooth Headset.
See also other articles linked on the top right.

If your PC doesn't have Bluetooth built in, a USB adapter is inexpensive and simple to add.

But don't buy a D-Link adapter.  Their service is dreadful!

The number of ways to wirelessly connect an increasing number of formerly wired devices is becoming confusing. Wi-Fi, 802.11a, 802.11b, 802.11g, GPRS, IrDA and Bluetooth are just some of the terms now being used to describe different types of wireless connectivity.

This article explains the differences between the main types of wireless connectivity, and explains how Bluetooth can be useful for you.

Different Types of Connectivity Compared

To start off the discussion, here is a table to show the major differences between the main types of wireless connectivity and traditional networking.

Type Speed Range Comment

IrDA

9.6kb - 115kb (- 4Mb)

< 6ft

Infra-red.  The two devices must have their IR ports facing each other.  For simple data exchange.  Uses very little power.

Wi-Fi

1Mb - 54Mb see below Wi-Fi refers to any of the three 802.11 types of wireless service below, and to future new subcategories yet to be released.  Acts like a regular wired network in most respects.  Either built in or available as add-on cards or adapters for desktop computers.

802.11a

1 - 54Mb

50ft - 150ft

Not commonly used, uses different frequency than 802.11b/g.

802.11b

1 - 11Mb

100ft - 300ft

Most common version at present.

802.11g

1 - 54Mb

120ft - 350ft

The latest version, backwardly compatible with 802.11b.

Bluetooth

120kb - 3Mb

30ft - 300ft

Class 3 devices (eg in most personal computing type devices) have a short 30ft range, high powered Class 1 devices have the longer range, and Class 2 are somewhere in between.  Either built in or available as add-on cards.

Faster data rates possible with v1.2 (1 Mbit/sec) or V2.0 + EDR (3 Mbit/sec).

GPRS

< 115kb

wherever suitable cellphone coverage

Data service used by GSM cellphones and by some add-on cards for laptops and pda's.  Speed typically about 30kb depending on how many users are sharing the service on each cell at any given time.  A 2.5G service.

2.5G

variously up to about 128kb

wherever suitable cellphone coverage

Various compromise new types of 'always on' data service for cell phones that are better than nothing but not nearly as good as the 3G service that all cell phone companies are hoping to introduce when funding and technology allows.

3G

varies widely, up to about 7Mb

wherever suitable cellphone coverage

A current technology now becoming more common in the US which promises amazingly fast data transfer.

4G is under development with even faster speeds.

Modem

< 56kb

not wireless

The 'old fashioned' way to dial up from a computer to the internet.

DSL/Cable

100kb - 1.5Mb

not wireless

Not wireless.
'Broadband' connections to the internet.

LAN

10Mb - 10 Gb

not wireless

Not wireless.
Common type of cabled network in most offices (using Ethernet cabling).

So What is Bluetooth?

Bluetooth is a very simple type of wireless networking that can allow up to eight devices to be connected together in a mini-network.

It is very short range in operation, and so is considered to be for 'personal' networking. With a range typically under 30ft, this allows enough distance to perhaps communicate across your office, but not any further. This short range is also its major security feature - anyone wishing to eavesdrop on your Bluetooth communications would not only need special equipment but would also need to be quite close to you.

It is a moderately slow type of networking, but it can transfer data sufficiently fast enough for most typical applications.

Bluetooth is hoped to be a very low cost type of networking, and, as it becomes more widespread, the cost of adding Bluetooth to devices should drop down to perhaps no more than an extra $5-10 on the selling price.

Bluetooth is designed to be compatible across a range of very different operating systems and devices, including things that you would not normally think of as being 'computer' type items - for example, some types of headset. Bluetooth networking can enable the headset to connect with other devices such as your phone, your MP3 player, your computer, or your PDA.

A Bluetooth enabled headset would mean that you can leave your cellphone in your pocket or briefcase, but still receive incoming phone calls. If your cellphone supports voice recognition for dialing out, you can even place calls as well as receive them, while never needing to reach for your phone. The safety benefits of this, if you're driving, are obvious.

It is probably better from a health point of view to have a very low powered headset close to your head than it is to have a phone that might be generating 100 or even 300 times as much radio energy close to your head.

Bluetooth can also help different devices to communicate with each other. For example, you might have a phone, a PDA, and a computer. If all three devices have Bluetooth capabilities, then (with the appropriate software on each device) you can probably share contact information between all three devices quickly and conveniently. And you can look up a phone number on your PDA (or laptop) and then place a call direct from the laptop or PDA, without needing to touch your cellphone.

Bluetooth is not a magical solution giving universal connectivity between devices. Each device also needs to have the appropriate software as well as the basic Bluetooth communication capability, and so sometimes the promise and theory of what could be possible is not fully matched by the reality.

For best compatibility, devices should support the Bluetooth 1.1 standard. A new standard - 1.2, was formalized in early November 2003 and this is now the dominant standard.  A newer Bluetooth 2.0 standard, allowing for three to ten times faster network speeds, and more careful use of battery power, is becoming widely adopted.

Bluetooth has been slow to become accepted in the market, but now is starting to become increasingly prevalent. Prices are falling and increasing numbers of devices are offering Bluetooth connectivity. Over one million Bluetooth devices are now being sold every week (although mainly outside the US).

More information on Bluetooth can be found on the official Bluetooth website.  And here is a very useful site full of information on how to get Bluetooth devices communicating with each other and your PC.

Bluetooth Range

Bluetooth has three different defined ranges, based on their output power ratings.

Class 1 devices are the most powerful.  These can have up to 100 mW of power, and a regular antenna will give them a range of about 40 m - 100 m (130 - 330 ft).

Class 2 devices are lower power, with up to 2.5 mW of power.  A regular antenna will give them a range of about 15 m - 30 m (50 - 100 ft).

Class 3 devices use even less power, with up to 1 mW of power.  A regular antenna will give them a range of about 5 m - 10 m (16 - 33 ft).

Most Bluetooth devices will be Class 2 or Class 3.

Greatest range is not necessary the best

Bluetooth has never been intended for anything other than very short range communication.

With Bluetooth, short range is actually a benefit for two reasons.  Firstly, it reduces the chance of interference between your Bluetooth devices and those belonging to other people nearby.  This is a very basic type of security measure.

Secondly, lower power means longer battery life.  Most Bluetooth applications get their power from a battery, and anything that can be done to lengthen the life of the battery is obviously important.

More powerful Bluetooth devices can run into (and/or cause) problems due to swamping too many other Bluetooth devices with their signals and exceeding the eight device per network limit.

Devices that Use Bluetooth

A limited, but growing number of devices use Bluetooth at present. Devices that are starting to have Bluetooth connectivity built in include :

  • Digital cameras and camcorders
  • Printers
  • Scanners
  • Cell Phones
  • PDAs
  • Laptops
  • Keyboards and Mice
  • Headsets
  • In-car handsfree kits
  • GPS navigation receivers
  • Home appliances (microwaves, washers, driers, refrigerators)

In addition, add on Bluetooth adapters are available for computers (eg with a USB interface) and for PDAs (eg SD cards).

Bluetooth and the Internet

Bluetooth can be used to connect between a device that has internet connectivity and another device that does not, for example, you might use Bluetooth to connect from your PDA to your laptop, and then your laptop might use Wi-Fi to connect to a Wi-Fi router and from there you would be connected to the internet.

Sometimes when buying a PDA you may find yourself with an apparent 'either//or' choice - either buy a device with Bluetooth; or a device with Wi-Fi capability. In such a case, it would seem at first glance that if you want to connect to the internet - especially while traveling out of your office, Wi-Fi would be a better choice.

However, this is not quite such a clear choice. Wi-Fi 'hotspots' are few and far between. A much better approach might be to get Bluetooth on your PDA and also on your cellphone and use Bluetooth to connect to your cellphone and then connect through your cellphone and out to the internet from there. I use T-Mobile's GPRS service - they offer unlimited connect time and unlimited bandwidth usage for only $20/month extra on top of my regular cellphone service (and GPRS connection time does not count against my monthly minutes - it truly is unlimited for only $20/month).

In my opinion, this is the perfect solution. GPRS coverage is much more widespread than Wi-Fi coverage, and while it is not fast, it is adequate for simple mail sending/receiving, instant messaging, and occasional web browsing such as you're likely to do on a PDA. Although I also have Wi-Fi in my laptop, these days I never use it, and indeed if I'm sitting in a Starbucks with my laptop, I'll be connecting to the internet not through the Wi-Fi in Starbucks, but via Bluetooth and my cellphone's GPRS!

Which is better - Bluetooth or Wi-Fi

Wi-Fi is primarily used as an alternate to traditional cable based networks. It has a longer range than Bluetooth, and supports faster data transfer speeds, and so it might seem better than Bluetooth.

But, in reality, Bluetooth and Wi-Fi have different purposes. Bluetooth is intended for limited data transfer between many different types of devices, Wi-Fi is more focussed on faster data transfer between computers on a network.

One of the distinctive elements of Bluetooth is that is uses very much less power than Wi-Fi. Class 3 devices (such as are in PDAs, phones, headsets, etc) transmit a very low power signal (1 mW) and only transmit intermittently when in standby mode, saving even more power. Wi-Fi, on the other hand, consumes a great deal of power, and so for any type of portable battery operated device, Bluetooth will allow for substantially more battery life than would Wi-Fi.

If you're simply wanting to swap data between different devices in your office and elsewhere on a casual and occasional basis, then - assuming that the software and Bluetooth hardware is available - Bluetooth is probably a better choice for you. If you need more range, and higher bandwidth; perhaps if you want to connect computers into your office LAN, then Wi-Fi is a better choice for you.

Bluejacking

Bluejacking is a moderately harmless 'fun' type trick that some people have discovered. It involves sending messages from your Bluetooth device to other people close to you with Bluetooth devices, and surprising the recipient in the process.

The easiest way to Bluejack is to create a new phonebook contact, with the message you want to send in the name field. Then, in a busy place with lots of people (so that there is a chance that someone might have a Bluetooth enabled phone or PDA), choose the option to send your new contact via Bluetooth. Your phone or PDA will then search for all Bluetooth devices in range, and present you with a list. Choose whichever device you wish from the list and send it. The recipient will get a message asking if they wish to accept your contact, and showing the text you entered as the contact's name (eg something like 'Bad weather today isn't it' or whatever else you wish to say).

More details on Bluejacking can be found on this website.

If you're planning to enjoy Bluejacking (or Toothing, below) you'll probably want to get your eye in to guessing how far away 10 m/33 ft is so as to know how many people and devices might be within range.

Toothing

Harmless Bluejacking didn't take long to evolve into a more goal oriented social activity, now known as 'toothing', whereby people communicate to other Bluetooth equipped people around them, trying to arrange casual and immediate trysts.  Discussed in this article and more information on this website.

Summary

Bluetooth promises to be a low cost, convenient, and simple way of enabling your various computer devices to talk to each other and to their peripherals. The reality has yet to match the promise, but Bluetooth is becoming more widespread and functional every day. Bluetooth is almost certainly in your future.

Bluetooth is not a competitor to Wi-Fi. It offers different functionality for different purposes.

Part 1 of a series on Bluetooth

Please also see How to Choose a Bluetooth Headset.
See also other articles linked on the top right.

Originally published 20 Nov 2003, last update 15 May 2010
You may freely reproduce or distribute this article for noncommercial purposes as long as you give credit to me as original writer
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