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Author Topic: Wireless 802.11g  (Read 1757 times)

Offline bat69

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Wireless 802.11g
« on: March 11, 2003, 16:41 »
Tom's Hardware Guides has published the 802.11g: Need-To-Know, Part 1

Go HERE for the full article. But here is the introduction as a taster:

Introduction

The wireless networking world is a'buzz with the new kid in town, 802.11g. As with most new technologies, some of the buzz is hype, some is rumor, and it's hard to tell the difference! Fortunately, one of the advantages that we have is detailed test data from the first products to hit the shelves, which I can use to help separate fact from fiction. I've also been busy corresponding with both the chip and networking product companies involved in the draft-802.11g market-share battle, most of whom have been very helpful in helping me get a better understanding of this new technology.

Part 1 of this NTK will try to address many of the questions that are being asked about 802.11g and draft-802.11g products. It will also try to answer the practical questions: Should I buy now? And if so, what should I buy?

Although I originally intended to put everything into one NTK, I found that there was just too much information to put into one article! Part 2, which will follow in a week or so, will present more of the test data that I've used to draw my conclusions. Let's get started!


What is it?

802.11g is a new IEEE standard for wireless LANs that is currently in draft form, and expected to be ratified (finally approved) in July 2003. I'll explain more about the implications of this later. Its key claims to fame are its 54Mbps raw data rate and 802.11b backward compatibility.

802.11g's higher speed comes from using the Orthogonal Frequency Division Multiplexing (OFDM) modulation scheme - the same as used in 802.11a. Backward compatibility comes from using the 2.4GHz band, supporting the old Complementary Code Keying (CCK) modulation scheme used by 802.11b, and new "protection" mechanisms described in the 11g draft standard.

802.11g's negatives are the same as 802.11b's, i.e., only three non-overlapping channels and interference from cordless phones and microwave ovens. So if you're having interference problems with your 802.11b network, you'll still have them with 802.11g.

Broadcom's 54g FAQ describes some of the technical details of the draft specification, which includes:

A new physical layer for the 802.11 Medium Access Control (MAC) in the 2.4 GHz frequency band, known as the extended rate PHY (ERP). The ERP adds OFDM as a mandatory new coding scheme for 6, 12 and 24 Mbps (mandatory speeds), and 18, 36, 48 and 54 Mbps (optional speeds). The ERP includes the modulation schemes found in 802.11b including CCK for 11 and 5.5 Mbps and Barker code modulation for 2 and 1 Mbps.
An optional MAC mechanism called RTS/CTS that governs how 802.11g devices and 802.11b devices interoperate. RTS/CTS is also optional in 802.11b.

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Offline bat69

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Re:Wireless 802.11g
« Reply #1 on: March 19, 2003, 15:47 »
And HERE is part two of the 802.11g Need-To-Know guide

and for a little taster:  ;)



In this second and final part of the NTK, I'll go into more detail on the performance differences that you'll find between current Linksys and Buffalo Tech products. I'll also present the results of my first detailed performance tests for products based on Intersil's PRISM GT chipset.

A Closer Look at "Interoperability"

Much has been made in the press over the past month or so about "interoperability problems" among draft-11g products. From what I've seen, however, this may be partly a "whisper campaign" to spread FUD to slow down the competition and partly due to incorrect conclusions drawn from the use of inadequate test methodology.

Although you may be inclined to think "functional issues" when you hear "interoperability problems," my testing with draft-11g devices has shown throughput variation to be the dominant interoperability issue. In some cases, however, the interoperability effect on throughput is so severe that it can easily be mistaken for a functional problem if simple file transfer or another technique that looks only at average or total throughput is used.
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Offline Hitch

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Re:Wireless 802.11g
« Reply #2 on: March 19, 2003, 16:10 »
Sweet dude... looks like my kit is old already :( wonder what price were gonna be talking?

Offline Clive

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Re:Wireless 802.11g
« Reply #3 on: March 19, 2003, 21:41 »
I read in a magazine article this week that the range of a wireless connection can be extended by using an empty dog food can.  I'm serious!!  Unfortunately they didn't explain how it is done.  Maybe you are supposed to place the can over the antennae.
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Offline Clive

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Re:Wireless 802.11g
« Reply #4 on: March 20, 2003, 17:36 »
An interesting wireless website which even explains the dog can improvement can be found at:

http://www.sydneywireless.org/
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Offline Hitch

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Re:Wireless 802.11g
« Reply #5 on: March 21, 2003, 01:10 »
where? cant find it mate

Offline Clive

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Re:Wireless 802.11g
« Reply #6 on: March 21, 2003, 08:35 »
Under Antenna then cantenna.

http://www.oreillynet.com/cs/weblog/view/wlg/448
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Offline Hitch

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Re:Wireless 802.11g
« Reply #7 on: March 21, 2003, 15:55 »
Cheers


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