Is Bluetooth a Viable Alternative to 802.11b?
by Wei-Meng Lee11/21/2002
This article is not a point-by-point comparison of Bluetooth versus 802.11b. There are many good places on the Web to get that information, such as this resource page on wallstreetweb.nl.
What I will do here, however, is provide some detail about my recent experience of using a Bluetooth Access Point for Internet connectivity and consider the notion of using Bluetooth in place of 802.11b wireless networking (in certain situations).
Using the Bluetake Bluetooth Access Point
The test unit that I'm working with is the Bluetake BT300 Bluetooth Access Point (AP), which is Bluetooth 1.1 compliant and supports an operating range of 100 meters (300 feet). The AP comes with two interfaces: RS232 and a 10/100 Base-T Ethernet port. It supports the Bluetooth LAN Access profile and operates at a maximum data rate of 1Mbps.
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| Figure 1 -- The Bluetake BT300 Access Point |
To connect the AP to the network, I plugged it in into my network hub and powered it up.
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| Figure 2 -- The Bluetake Class 1 (100 meters) USB Bluetooth dongle and a Class 3 (10 meters) Billionton USB Bluetooth adapter |
I used two USB Bluetooth adapters: one from Bluetake (the BT007 Bluetooth USB Dongle) and one from Billionton (the USBBT02-X Bluetooth USB adapter). The BT007 Bluetooth adapter is a Class 1 device, which means that it has a wider operating radius of 100 meters (300 feet). The Billionton adapter, however, is a class 3 device, operating at a range of 10 meters (30 feet). Both can transmit at a maximum rate of 1Mbps.
After installing the Bluetooth software provided by the USB Bluetooth adapters, I am able to use it to perform a search for the AP. If the AP is working correctly, you should see the AP, as shown in the diagram below:
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| Figure 3 -- Searching the Bluetooth Access Point |
Once the AP is found, right-click on it and select Connect LAN Access using PPP.
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| Figure 4 -- Using PPP to connect to the Access Point |
The computer will then attempt to establish a PPP connection with the AP.
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| Figure 5 -- Establishing a connection to the Access Point |
When prompted for User name and password, simply leave it empty and click Connect.
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| Figure 6 -- No authentication needed |
That's it. Your computer is now connected to the AP. You can view the status of the PPP connection by right-clicking on the LAN Access using PPP icon (which appears after the successful PPP connection) and selecting Status.
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| Figure 7 -- Check the signal strength in the Status window |
Here you can see the signal strength of the connection. If you were sitting right next to the AP, you would obviously get a good signal, but if you are separated from your AP by walls, you probably get a weak signal.
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| Figure 8 -- Signal strength is dependent on how far you are away from the AP |
I realized that the default maximum speed is set to 115200 bps, which does not do justice to Bluetooth, as it is capable of a much higher data rate. So you probably need to set it to a higher number, which is 921600 bps for my case.
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| Figure 9 -- Setting the connection speed to the highest you can find |
The AP by default comes with a fixed IP address of 1.1.1.1, and you can configure it using your Web browser. You can set the AP to use DHCP as well as set a passkey (PIN code) for authenticated access. Remember to set the Security level to Level 3 if you want to enable this feature. Be sure to disable your proxy server access in your Web browser before you configure the AP.
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| Figure 10 -- Enabling passkey access |
With that set, the next time someone tried to connect to the AP, they will be prompted with the passkey request.
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| Figure 11 -- Prompting for a passkey |
Performance Issues
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Related Reading 
802.11 Wireless Networks: The Definitive Guide |
With my AP in place, I went ahead to test the connection using my two USB Bluetooth adapters. Performances were comparable except that the Class 1 Bluetake Bluetooth adapter is able to operate at a longer distance. I was able to surf the Web comfortably, without any noticeable difference. One thing I gathered is that Bluetooth works best if there are a lot of free spaces for the radio wave to reach you. I tried locating the AP in a closed room (with concrete walls) and tried accessing the network two rooms apart, and the signal drops to a rather weak level. I did, however, still maintain the connection, albeit a slow one. With Bluetooth, you can connect up to seven devices to the AP, a number that should be sufficient for most home use.
There have been many debates as to which is the ultimate wireless technology that will prevail, and I fully subscribe to the suggestion that Bluetooth is a wire replacement technology, whereas 802.11b is more suitable for network connectivity. However, in certain environments, Bluetooth can be an attractive option for setting up a network.
Most cable modems in the home operate at a speed of 256 or 512 bps. While your 802.11b operates at an 11Mbps speed, it is nevertheless capped by the speed of the cable modem. Add to that, network latency and server delays effectively reduce the actual bandwidth that you get from your cable modem. So, even if you have a fast connection from your computer, you are not fully realizing the benefits from it.
This is where Bluetooth is attractive. The theoretical speed of 1mbps (lower in practice) is still significantly higher than the speed of your cable modem. In terms of cost, the price of Bluetooth adapters and AP are dropping. You can get a Bluetooth AP for around $100 and an adapter for $50.
For coverage, while Class 3 Bluetooth devices have significantly lower operating radius than 802.11b, Class 1 devices with wider operating range are actually suitable for the home environment.
One final word about performance. If you are operating an 802.11b network together with Bluetooth, Bluetooth performance will take a hit. Since they both operate in the 2.4Ghz spectrum, collision of packets will cause Bluetooth devices to resend. Hey, if your mum is operating her microwave in the kitchen, that is also going to interfere with your wireless network. As I was testing in an environment where 802.11b is prevalent, I was not able to do an accurate test of the comparative transmission rate. But hey, I was able to watch without problems the latest version of The .NET Show using my Bluetooth connection.
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| Figure 12 -- Watching the 300K stream version of The .NET Show |
Summary
I know the topic of Bluetooth versus 802.11b is a fiercely debated one. And I'm bracing myself for some interesting feedback. For me, Bluetooth technology works fine at home. It's also a useful tool to use in the classroom, where I can provide network access (though my network-connected, Bluetooth-enabled notebook) to students equipped with Bluetooth-enabled devices (such as PDAs). Tell me where you have successfully used Bluetooth.
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Related Reading Windows XP Unwired |
You must be logged in to the O'Reilly Network to post a talkback.
Showing messages 1 through 12 of 12.
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Bluetooth safer than WiFi
2003-01-29 16:56:31 anonymous2 [Reply | View]
802.11b was designed as an open architecture - easy to add new machines, but hard to lock it down (as many many articles/web pages/shows have shown). Bluetooth is designed to be more secure - the required 'pairing' before devices will even think about talking...and I _love_ the ~30 foot range (on the class 3 devices) - it's enough to allow all the computers in my pad to talk to each other but nobody "driving by" will be able to see a thing!
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Bluetooth do slow down 802.11b
2003-01-12 05:20:48 anonymous2 [Reply | View]
Not the other way around.
At least when I tested, I could keep having filetransfer over bluetooth at high speed, my adapter had a max at 768Kbit/sec (most bt devices still have), despite BT support for max 1Mbit.
So BT transfered the files OK, but the 802.11b connection slowed down considerably, and went nearly slower than bluetooth.
Tried files of size 1GB, from one Mac to another.
I have been told its like this, because bt doesnt check before sending, its quite brute. That will be fixed in revision 1.2.
Dont understand how Ericsson could lower their bar so much, as to do that implementation in BT. They ought to know better.
orjan@mac.com
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Biggest advantage over 802.11
2002-12-16 09:35:41 anonymous2 [Reply | View]
Bluetooth currently has a working standard security model. That's why it can be used in brokerages, where any use of 802.11 is forbidden.
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RE: 802.11b and Bluetooth coexist
2002-12-09 12:52:45 anonymous2 [Reply | View]
Bluetooth is a frequency-hopping technology, 802.11b is direct-sequence spread spectrum (DSSS). This means that 11b transmits across a wide channel (22MHz), while Bluetooth rapidly hops through a sequence of narrow channels. So when "collisions" occur, bluetooth tranmissions will likely experience interference, but 11b should not be affected since the "noise" should be averaged out. -
RE: 802.11b and Bluetooth coexist
2003-05-23 10:29:43 anonymous2 [Reply | View]
Bluetooth's dominence in the low power sector of the market means when it is running as a class 2/3 device at 4dBm or 0dBm which covers adequate distance of 10m it does not guzzle your power in your mobile device this is why it is prefered to 802.11b. Now the question that poses is well since we are going to slap it in our mobile systems should we start to look at it's viability as a WLAN..... I think no! It serves well for ftp and sync work and even cable replacement but I fear by splitting the stack into a services orientated thing it seems to have taken away the simplicity it was originally intended to bring with it. I think technical knowledge needs to improve around this standard and the realisation that if you want to research into it it's very time consuming (opensource project 18mnths with experts in different fields. My concern is OK when we operate Bluetooth /802.11b side by side they don't seem to impact to much. That is Bluetooth on 802.11b because of it's ruthless way over 802.11b's curtious approach sniff first, but reality says when Bluetooth floods the market and now we are talking scatternets the more spectral density these collisions are going to occur more frequent and boy when you take your phone and laptop into work along with every one else in the coorporation you could end up grinding the system to a halt. 802.15 TG2 have come up with avoidance techniques for these technologies to employ and I think this will be the way forward.... -
RE: 802.11b and Bluetooth coexist
2003-05-23 10:27:12 anonymous2 [Reply | View]
Bluetooth's dominence in the low power sector of the market means when it is running as a class 2/3 device at 4dBm or 0dBm which covers adequate distance of 10m it does not guzzle your power in your mobile device this is why it is prefered to 802.11b. Now the question that poses is well since we are going to slap it in our mobile systems should we start to look at it's viability as a WLAN..... I think no! It serves well for ftp and sync work and even cable replacement but I fear by splitting the stack into a services orientated thing it seems to have taken away the simplicity it was originally intended to bring with it. I think technical knowledge needs to improve around this standard and the realisation that if you want to research into it it's very time consuming (opensource project 18mnths with experts in different fields. My concern is OK when we operate Bluetooth /802.11b side by side they don't seem to impact to much. That is Bluetooth on 802.11b because of it's ruthless way over 802.11b's curtious approach sniff first, but reality says when Bluetooth floods the market and now we are talking scatternets the more spectral density these collisions are going to occur more frequent and boy when you take your phone and laptop into work along with every one else in the coorporation you could end up grinding the system to a halt. 802.15 TG2 have come up with avoidance techniques for these technologies to employ and I think this will be the way forward.... -
RE: 802.11b and Bluetooth coexist
2002-12-14 08:36:43 cbaatar [Reply | View]
Can someone tell me what Bluetooth does that 802.11b CANNOT? Reading Wei-Meng's article, I get the impression that BT is merely a "me too" type technology. An earlier post claims that BT is better for connecting computers and 802.11b is better for networking. But what's the difference? Doesn't a 802.11b based home LAN (or HAN) necessarily "connect" home computers together?
I'd appreciate if someone could clarify this for me.
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802.11b and Bluetooth coexist
2002-12-03 03:39:32 anonymous2 [Reply | View]
shouldn't be 802.11b taking a hammer when it's coexist with Bluetooth because BT frequency hoops 1600 times in a second? Have you actually tested their coexistence?
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Consider using PNG
2002-11-26 14:31:03 anonymous2 [Reply | View]
Consider using PNG's instead of JPG's for your screenshots. JPG's just aren't suited to high contrast images, causing the smearing and blurring seen in these images.
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macblue.sh
2002-11-25 06:18:42 Brian Jepson [Reply | View]
Cliff Skolnick's macblue.sh script runs a ppp daemon with nat support on Mac OS X's Bluetooth-PDA-Sync port so you can connect to it from another device and get on the Internet. It's similar to the LAN access point idea.
http://www.toaster.net/wireless/bluetooth/
The script includes instructions for connecting from a PalmOS device, but it could probably be adapted for others.
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Bluetooth vs. 802.11b?
2002-11-24 07:19:17 anonymous2 [Reply | View]
I didn't realize they were competing. That seems like USB competing with Ethernet, meaning one is a peripherial connection technology and the other is an inter-computer connection technology. I love Bluetooth (I have a Sony-Ericcson T68i and iSync is awesome) but I would never use it for networking. Pricing is mentioned as an issue, but I've seen 802.11b cards and access points for the same prices mentioned in the article in the latest Best Buy ad.
I guess if someone made this someone needs to review it, but the entire exercise seems like a geek project with little real world applications.
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Bluetooth faster than cable?
2002-11-22 21:27:30 mcarney [Reply | View]
Your cable may be well under 1mbs but mine is not. I regularly have bandwidth well above that -- up to 2mbs. Bluetooth is too little and too late. Ubiquitous and inexpensive equipment is built around 802.11 and it fits neatly into existing standards and infrastructure. The burden of proof required is substantial to justify having a second air interface on the same frequency as 802.11b and performing many of the same functions. Cable replacement? I have a wireless keyboard and mouse that I purchased three years for half the price of Bluetooth versions. The enormous effort on Bluetooth would be better spent producing a low power 802.11 device.
