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#8923 - 12/10/02 06:01 PM IEEE 802.11 Defined
Infinite Offline



Registered: 03/09/02
Posts: 1041
Loc: Canada eh
I had to write a comparison report as a final project in my Comm class. As I chose a technical topic I figured some of you may like to check it out. It's not hella technical, but it should give some of you a better understanding of what Wi-Fi is and how it works.

Also a shout out goes to pergesu, his mad proof-reading skills helped me a lot with the language I used. perg, I hope the rest wasn't too "passive" [kissmyass]

If you decide you like this and would like a copy of the original word document you can find it here: http://members.shaw.ca/theonesum/final.doc

Feel free to use this for whatever purposes you like, as long as it's unmodified and gives credit where credit is due.

=================================================================

Looking at WiFi

Wireless networking technology is still a relative newcomer in the IT industry. The technology is still more expensive then its wire counterparts, and does not offer the same bandwidth. Despite these current drawbacks WiFI is making an inroad into networks starting at the home user and going right on up to corporate business. The freedom of movement and ease of connecting to a network are fast making WiFi an attractive solution for today’s networking needs.

Currently on the market are two related WiFi technologies for creating wireless data networks; the older, better-known 802.11b, and the newer, faster 802.11a.

The similarities in name of the various WiFI standards can be a source of confusion for many people. To compound the problem further the 802.11b standard was finalized and made public before the 802.11a standard was, casting the continuity of the alphabet away. There is however many differences between the two standards.

When looking at wireless network solutions there are a few points to consider. Each of the two dominant technologies has their own strengths and weaknesses. Factors such as bandwidth and range play important roles, as does the ever deciding cost factor. As well upgradeability and scalability must be considered due to the rapid advancements made in technology today. The final point that should be considered when comparing these standards is security. While the average home user does not necessarily need to worry about upgradeability or scalability, the other criteria mentioned almost certainly will influence the final decision.

What is WiFi?

In 1990 the Institute of Electrical and Electronic Engineers (IEEE) formed the original 802.11 committee to establish set of standards for wireless local area networks (WLAN). It was seven years later that that committee approved the 802.11 standard and began what is known today as WiFi. The term WiFi is an acronym for Wireless Fidelity, and has been chosen to represent both the 802.11a and the 802.11b standards.

The original 802.11 standard was a break through in the world of computing. For the first time network connections did not require the typical mess of cables associated with networks. Access points could provide internet connectivity anywhere within their influence; networks no longer required cables for expansion, and mobile computers could remain connected as they moved about within the cell.

Around the same time that the IEEE approved the 802.11 standard, the 802.11 committee recognized the need for faster, more reliable methods of wireless data transmission in the future of WLANs. After the 802.11 committee released the original 802.11 standard they began working on these newer and better standards of the future. These new standards were given the names 802.11a through 802.11i. Of all these subgroups the 802.11a and 802.11b standards are the most noteworthy, with 802.11g deserving of a passing nod.

802.11a

The IEEE 802.11a standard defines data transmission using radio frequency (RF) transmission in the 5GHz range. The 5GHz Unlicensed National Information Infrastructure (UNII) band has relatively few devices operating with its boundaries. 802.11a utilizes an encoding scheme called Orthogonal Frequency Division Multiplexing (OFDM) to achieve a maximum transfer rate of 54Mbs. The indoor range is stated to be approx 100m, and an outdoor range approx 350m. Wired Equivalent Privacy (WEP) is used as the encryption mechanism for 802.11a.

802.11b

The IEEE 802.11b standard defines data transmission using radio frequency (RF) transmission in the 2.4GHz range. The 2.4GHZ range is an unlicensed radio band in which other devices such as microwaves, cordless phones, and the new Bluetooth devices operate. 802.11b utilizes an encoding scheme called Direct Sequence Spread Spectrum (DSSS) to achieve a maximum transfer rate of 11Mbs. The stated indoor range is stated to be approx 150m, and an outdoor range of approx 500m. Wired Equilivent Privacy (WEP) is used as the encryption mechanism for 802.11b.

A note on 802.11g

The IEEE 802.11g committee is currently working on a third wireless data transfer standard in addition to 802.11a and 802.11b. The goal of the 802.11g committee is to create faster data transfer on the currently used 2.4GHZ band. This new standard will be backwards compatible with the 802.11b standard, and will offer transfer speeds of up to 54Mbs. As of this writing the standard has not been approved for release.

Radio Frequencies

When comparing WiFi standards the first point to consider is the frequencies at which a given standard operates. The difference in the operating frequencies between 802.11a and 802.11b make distinguishing one standard from the other easier. The 802.11b standard operates in the 2.4GHz band (2.4 GHz to 2.4835 GHz) while the 802.11a standard operates in the 5GHz band (5.725 GHz to 5.850 GHz). The properties of these two spectrums directly affect both the available bandwidth and range of WiFi.

The 2.4GHz range of frequencies is an unlicensed band used for various devices that emit RF interference. Medical equipment broadcasts in this band, as do microwaves. 802.11b’s Direct Sequence Spread Spectrum (DSSS) encoding utilizes the 2.4GHz band’s available three simultaneous channels of transmission to achieve a maximum transfer rate of 11Mbs.

The 5GHz range of frequencies is also an unlicensed band, but has been set aside for data transmission purposes. Therefore this spectrum does not have the amount of interference as the crowded 2.4GHz band. 802.11a uses Orthogonal Frequency Division Multiplexing (OFDM) to manage the eight available channels of simultaneous transmission to achieve transfer speed of up to 54Mbs.

One of the characteristics of RF transmission is that the signals degrade over distance. To compensate for this property of RF, both 802.11 standards discussed here decrease the transmission rate as the communicating nodes become farther apart. Each standard has a pre-set series of speeds to cycle through as the distances become greater or lesser. As 802.11a has a higher possible transmission rate it cycles through a broader range of speeds than does 802.11b

Cost

There are many makes and models of both 802.11 standards for sale today. 802.11b has been available for a longer period of time than 802.11a has, and has therefore “matured” somewhat. Generally a PCMCIA 802.11b wireless network card will cost about $120 for a low end model, and can reach about $300 for the high end models. In comparison, a similar PCMCIA 802.11a card would start at about $175 and can range to $500. When comparing access points the same ~50% difference in favor of 802.11b emerges. Both 802.11a and 802.11b prices have steadily decreased with time and continue to do so.

Security

Wired Equivalent Privacy (WEP) is the encryption scheme used for both the 802.11a and the 802.11b standards. WEP is a relatively efficient form of data encryption, and if implemented properly can provide a satisfactory level of security. However, there has been proven methods of circumventing WEP through the use of tools such as airsnort. Any deployment of WiFi should include other methods of security. In this respect 802.11a and 802.11b are equal.

Conclusion

In many respects the IEEE 802.11a and 802.11b standards represent two sides of a coin. 802.11a offers higher bandwidth at lesser distances while 802.11b’s range can nearly double its opponent at the cost of speed. The fact that realistically the transfer speeds offered by 802.11b are sufficient for most applications is not enough for rapid advancement the technology industry goes through.

802.11b has enjoyed deployment in the workplace for a longer period of time and therefore has a greater install base and lower prices, but this is changing. As data networks become more and more sophisticated the demand for the technologies of the future increase.

802.11a is an example of a technology designed to meet the next generation of issues facing wireless networks. The unlicensed 5 GHz range is an example of this; a dedicated, unlicensed spectrum purely for data transmission. No chance of your microwave taking down your network with 802.11a.

802.11b does stand one chance of living on: 802.11g. 802.11g being designed to operate in the 2.4GHz range will be backwards compatible with 802.11b. But as 802.11g is still in development it remains to be seen if it will challenge 802.11a in the future.



Works Cited

Flickenger, Rob “802.11b Tips, Tricks, and Facts” 03/02/2001
Online: http://www.oreillynet.com/pub/a/wireless/2001/03/02/802.11b_facts.html
(03/12/02)

Geier, Jim “802.11a becomes a contender” 06/17/2002
Online: http://www.nwfusion.com/reviews/2002/0617bg1.html
(03/12/2002)

Brown, Bruce “802.11a--Fast Wireless Networking”
Online: http://www.extremetech.com/article2/0,3973,83888,00.asp
(03/12/2002)

Athena Semiconductors Inc. “Technology”
Online: http://www.athenasemi.com/technology/
(03/12/2002)

Geier, Jim “The BIG Question: 802.11a or 802.11b?” 01/24/2002
Online: http://www.80211-planet.com/columns/article.php/961181
(03/12/2002)

Moran, Joseph “Wireless Home Networking, Part II - Wi-Fi Standards” 11/05/2002
http://www.80211-planet.com/tutorials/article.php/1495031
(03/12/2002)

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#8924 - 12/10/02 07:59 PM Re: IEEE 802.11 Defined
BackSlash Offline
UGN's Resident Homo

Registered: 03/16/02
Posts: 599
Loc: TN
nice article sum
_________________________
"It's better to burn out, than to fade away."

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#8925 - 12/10/02 08:06 PM Re: IEEE 802.11 Defined
§intå× Offline


*****

Registered: 12/03/02
Posts: 3255
Loc: Maryland
Very nice! I was just reading the latest Telephony on this. Verizon is banking very heavy on this catching on in the near future. It didn't answer all my questions, however gave me some new ones to look into. Mind if I post additional info below this post?

Such as research notes on WEP, and maybe some protocol/data packet info here?
_________________________
My New site OpenEyes

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#8926 - 12/10/02 08:17 PM Re: IEEE 802.11 Defined
§intå× Offline


*****

Registered: 12/03/02
Posts: 3255
Loc: Maryland
2 tools to crack WEP

http://airsnort.shmoo.com/

http://sourceforge.net/projects/wepcrack

A pic to illustrate how WEP encrypts. Rad about it here.

http://www.wirelessdevnet.com/articles/80211security/
_________________________
My New site OpenEyes

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#8927 - 12/10/02 09:58 PM Re: IEEE 802.11 Defined
Infinite Offline



Registered: 03/09/02
Posts: 1041
Loc: Canada eh
No, post away. We might as well turn this thread into one big wireless circle-jerk.

I realize I left out some of the more fundamental aspects of WiFi. But seeing as how I threw most of this together in one night while really baked, and that I was aiming to satisfy the criteria of the assignment and nothing else, it'll have to do.

But yeah, post any additional info, and ask those unanswered questions. For once I might be able to answer.

Infinite

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