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802.11g Approved By IEEE 54 mb/s on 2.4 gigahertz 141

Posted by Hemos from the but-it-interferes-with-my-phone dept.
wavecentral writes "IEEE just approved the 802.11g as the new standard in a vote late Thursday. This enables data transfer rates of up to 54 megabits per sec and works on the 2.4 gigahertz band that 802.11b uses. This in turn makes it compatable and operable between the offical standard." Ewann also writes: "By mid-2002 we should be seeing products based on this technology. Unlike 5 GHz 802.11a, 802.11g is backwards compatible with the huge installed base of 802.11b products. Cool stuff if you want to wirelessly stream video and music in your home. More info on 0211-planet."
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802.11g Approved By IEEE 54 mb/s on 2.4 gigahertz More

802.11g Approved By IEEE 54 mb/s on 2.4 gigahertz

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  • It's great that this is backwards compatable, transitioning from one technology is very difficult in itself, going cold turkey where you have to get rid of your current hardware and migrate completely is even worse.

    Being able to use your current stuff in conjunction with the new stuff is what will make technologies like this able to improve and expand.

  • Interesting plug (Score:1, Flamebait)

    by brunes69 ( 86786 )

    I find it interesting and/or odd that the line "3Com Corp., Cisco Systems Inc. and Intel Corp. are among the largest makers of wireless LAN equipment." is at the end of the yahoo article, even though NONE of these companies are mentioned anywhere in the article. Nice side-fact, or prehaps they are sponsors?

  • Interoperability with 802.11b is nice and all, but at least 802.11a uses reserved frequencies.
    • Correct me if I'm wrong, but I believe the frequency band used by 802.11a is also unlicensed. The only difference is that there aren't a lot of devices out there using it, as compared to 2.4GHz.
      • I believe that you are both right. There are bands for
        both licensed and unlicensed. I belive there are 8(?) unlicensed bands, and 3(?) licensed. I don't have a reference handy, and don't feel like looking it up. Perhaps someone knows the exact numbers? Oh, and this would only apply in the US. Just as with current 802.11b, different countries reserve different numbers of frequencies.
    • Whoever modded this up as "Informative" ought to read a book.

      802.11b, and 802.11a, use unlicensed frequency ranges. These ranges fall in the 900Mhz, 2.4Ghz, and 5Ghz bands.

      Together, the 3 bands are referred to as the ISM bands, standing for Industrial, Scientific, and Medical.

      • This is true in the US, but strangely enough there are other countries in the world - many of them (e.g. Europe) have only licensed spectrum at 5 GHz. Please remember that the US != The World....

        802.11b uses 2.4 GHz, as does .11g. 802.11a uses 5 GHz. Neither uses 900 MHz, of course.
    • Good point, but OFDM and PBCC are both supposed to be much more adaptive and responsive to frequency interference, both temporary and permanent. My understanding of OFDM is that it has some properties in common with DMT (Discrete Multitone Transform) which is part of the wavelet-based algorithm for encoding in higher-speed DSL system. DMT channelizes available bandwidth into smaller chunks, each of which has a QAM-style modulation like an individual modem. So each channel can be responsive to errors and interference, and entire channels can be shut down without radically altering the entire bandwidth profile. Further, you can step down the whole chunk (all channels) to a lower speed and still benefit from channelization within that lower speed.

  • Nice cheap labor (Score:4, Funny)

    by Reality Master 101 ( 179095 ) <RealityMaster101@gmail. c o m> on Friday November 16, 2001 @08:04PM (#2577047) Homepage Journal

    This inturn makes it compatable and operable between the offical standard.

    Man, my interns only fetch coffee and occasionally do some copying. Where do I get these interns that are able to design wireless networks? Come to think of it, where do I get Clinton-style interns?

  • Cool stuff if you want to wirelessly stream video and music in your home.

    Yup. And the neighborhood too. Can you imagine a realtime babysitter network of these things? Or, perhaps a pet watching service...

    (Hoping the frequency gives this kind of range)

  • Article on eetimes (Score:5, Informative)

    by morcheeba ( 260908 ) on Friday November 16, 2001 @08:06PM (#2577053) Journal
    more info at eetimes [eetimes.com]

    The final proposal calls for two mandatory modulation/access schemes of complementary code keying (CCK) used in 802.11b and the newly allowed orthogonal frequency division multiplexing (OFDM) used in the 5-GHz 802.11a standard. As an option, however, the 802.11g proposal allows for the inclusion of Intersil's original CCK-OFDM scheme, which supports rates of 6 to 54 Mbits/s, and of TI's PBCC-22 (packet binary convolutional coding) method, which supports rates up to 33 Mbits/s.

    Three possible coding schemes? This will either drive the price up (to support all three), or lead to incompatibilities when only portions of the spec are implemented. I'd love to find out more... is there some negiotiation in the protocol too see what coding methods are supported?
    • No problem with incompatibilities. There are the two mandatory schemes, which must be available on all devices. If a particular manufacturer wants to implement the optional schemes then that scheme can be used to communicate with similar equipment, with CCK or OFDM as a fallback.

      Although the data rates for the optional schemes are no faster, it's possible they may be more robust in some circumstances, which I guess is why they're there.

      There's already negotiation in 802.11b to support the various codings already used (1-2Mbps, 5Mbps, 11Mbps). Since 802.11g is meant to backwards compatible this must still be used.

  • Unlike 5 GHz 802.11a, 802.11g is backwards compatible with the huge installed base of 802.11b products.

    But will it be backwards compatible with 802.11a?

    • Re:Compatibility (Score:2, Informative)

      by 90XDoubleSide ( 522791 )
      No, they operate on different frequencies, and 802.11g packets are specifically designed to begin the same as 802.11b packets to ensure backwards compatibility. For this reason, many people find 802.11a to be a silly gap-filling solution for fast wireless, especially considering its range.

  • Not just backwards compatibility (Score:5, Interesting)

    by 90XDoubleSide ( 522791 ) <ninetyxdoublesid ... minus herbivore> on Friday November 16, 2001 @08:12PM (#2577070)
    802.11a has very short range, which is why Apple did not implement it in its new AirPort products, but chose to wait out for 802.11g, which will offer the same range and backwards-compatibility. As was mentioned, the products probably won't be available until mid-2002. From an ITWorld article [itworld.com]: "The range supported from access point to client in an 11M-bit/sec network is about 300 feet. The shorter, wider radio waves in a 5GHz 802.11a LAN, while offering more capacity, transmit only about 90 feet."

    • The 802.11a range myth? (Score:4, Informative)

      by Wesley Felter ( 138342 ) <wesley@felter.org> on Friday November 16, 2001 @09:49PM (#2577334) Homepage
      FWIW, Atheros claims [atheros.com] that 802.11a works up to 225 feet and provides more bandwidth than 802.11b at any range. Take it with a grain of salt since Atheros makes 802.11a chips, but it's still worth a read.

    • Re:Not just backwards compatibility (Score:1)

      by Anonymous Coward
      It seems though that the outdoor range for 5 ghz products, for some reason, probably being initial power outpout, is up to 1600 feet (6 mbit, 1600 feet, using SMC's 5 ghz 802.11a product). Can you even get 2.4 ghz to 1600 feet using omnidirctional antennas and still be within the limits set by the FCC (Part 15 I think)?
      • Yes, you can get 2.4GHz to 1600 feet with omnis and stay within the FCC limits. Though, it depends on the vertical beamwidth you need to cover (antennas produce gain by changing the space covered - directional antennas produce a more tightly focussed beam whereas high-gain omnidirectional antennas produce more of a disc shape - this is an approximation though, you need to check antenna specs to determine the space covered).

        Note that at 5GHz you need a higher power output to cover the same space as at 2.4GHz.

    • The range supported from access point to client in an 11M-bit/sec network is about 300 feet.

      Not from any 802.11b product I have ever encountered. In fact, the existing 802.11b products I have tried are lucky to get anywhere near 90 ft in a real-world environment.

      I think whether 802.11a will be better or worse than 802.11b in real life remains to be seen. If its theoretical range is shorter it may actually work better in practice because there is less interference from neighboring users. And the 5GHz band is a lot less busy than the 2.4GHz band.

      • You said:
        > Not from any 802.11b product I have ever encountered

        He's talking about 802.11g, note the "g" at the end. No such products currently exist.
      • I have gotten well over 400' from an AirPort base station outdoors, and I get about 300' indoors, depending on how sturdy the building is. And that's with a product w/o a big external antenna. Of course TiBooks/iBooks tend to have better internal antennas than most products, that could have a lot to do with it. To compensate, you can always use a bigger antenna; people have gotten over 900' using an external antenna with an AirPort base station!

        The 5Ghz band does travel much more poorly than 802.11b/g in practice, but as you pointed out there is less interference, which could be beneficial if we ever start to get many hundreds or thousands of wireless users in a building. Many companies are compensating for the 5Ghz range problem by using big gain antennas like the ones that get 802.11b/g 900', which give 802.11a about 300'.

    • I have a range type question.

      I'm in an apartment building facing North. I have a friend about 10-20 floors below me (so at minimum there are 10-20 floors worth of concrete between us, I forget exactly what floor he's on).

      I have another friend in another building that is to the south-east of my building, and he's on the south side and 15 floors lower down. So that means he's probably got 1-2.5 times as much concrete in the way.

      What are my odds that *any* of these protocols will connect us? Even if we're using directional antennas? And what are the RF 'radiation' hazzards for the people living between us :)

      (There are no tall buildings at all to the north of our buildings, just 1-2 story residential houses.)
      • A friend of mine has an Apple Airport set-up, which is 802.11b, in a three story house, and there are dead zones inside the house, on the same floor!

        Your buddy in the other building might get some usage, with a high-gain directional antenna on your base station, depending on how well the signal can be reflected.

        Or, you could put antennaes on the roof on the south side of both buildings... There are rules [lns.com] to worry about though.

        Proxim [proxim.com] amd others have complete set-ups for you to try.

        Good Luck!

  • More details please! (Score:4, Interesting)

    by pwagland ( 472537 ) on Friday November 16, 2001 @08:14PM (#2577078) Journal
    If anyone can answer any of these questions I'll buy them a beer! the article is decidely fluffy on these details, and a quick google search turned up nothing of value...

    1) How does it achieve backwards compatability?
    1a) If you throw an 802.11b into an 802.11g network, what impact does it have on performance? i.e. does the 11b drag the network down?
    1b) How are broadcast packets sent? (11b or 11g standard?)

    2) Is 802.11g more or less resisant to "hostile RF". that 2.4Ghz spectrum is crowded, does 802.11g improve resiliance to interference?

    3) How is the range of 802.11g? I understand that the range of 802.11a (the other high speed wireless at 5Ghz) has a much shorter range due largely to the fact that it is at 5Ghz. Does 11g retain the strength of 11b here?

    4) What is the security protocol? We all know that WEP in 11b is broken....

    If yo uhave the information, please pass it on!
    • How does it achieve backwards compatibility:

      (This is pretty much an assumption, but I don't see any other possibility)

      802.11g hardware (clients) must be able to connect to 802.11b network access points.

      Conversely, 802.11g network access points must be able to accept incoming 802.11b connections, albeit at the slower speed.

      Because the two occupy different spectrums, there will be some duplication of components in hardware (therefore, a higher price).

      I could be wrong, but this looks like the way it's set up.
    • The correct answer is "I don't know", but I can tell you how 802.11b maintains compatability with 802.11. In order to maintain compatability between speeds in 802.11, all packet headers are sent at 1Mbps. That way, all clients can understand the basics that each access point is sending. When an AP is involved, the clients only talk to the AP and never to each other. So, as long as the client can tell the AP to send it's own packets at the right speed, everything is good.

      I'm pretty sure all the info needed for a client to participate in the collision avoidance algorithms, in contained in most basic of the packet headers (destination address, length (so it knows how long to keep quiet for), etc.) Clients don't need to be able to understand each other, or even the data portion of all the packets. The slower hosts will just ignore the faster packets, but will watch the headers in order to try and avoid collisions.

    • We'll give it a go, given my tyro's grasp of 802.11


      It's backwards compatible in that both 802.11b and 802.11g operate on the 2.4 GHz bandwidth. 802.11a will opereate on the 5 GHz bandwidth. Please keep in mind that 802.11g is not really there yet, so I don't know how b will affect on g's network. I would imagine that there'd be minimal impact.


      802.11g should have similar range to 802.11b. I think alot of the advantages from g come from their use of orthogonal frequency division multiplexing (OFDM). This provides the resistance to interference that g will enjoy.


      AFAIK, WEP is an extension of 802.11b. Even if it's in there, we all know it sucks, and we also know the steps necessary to ensure that your wireless LAN stays relatively secure.

    • Re:More details please! (Score:2, Informative)

      by zenyu ( 248067 )
      1-a) The radio is at the same frequency so the traces are the same width, the oscilator the same freq, etc. So the only difference is that you have different encodings.
      1+a) It shouldn't interfere at all, you have one AP that does both 802.11b & g, it starts out at a 1Mbps modulation, then it tries higher rates based on what both supports and the range permits.
      1+b) I don't have the standard, but I'd guess for 802.11b backward compatability it's at 1Mbps.

      2,3) I haven't read up on the different encodings, but basically you would have the same range as 802.11b but greater speeds only when the signal is good. If your far away you'll get 1Mbps, as you get closer the signal gets stronger 2,5.5,11,33,54 Mbps... I'd bet that you'll get better range with a new 802.11g card to an old 802.11b AP just because the radios will be better a year from now.

      4) You don't want this in the standard anyway. This is an international standard, encryption makes you a criminal in some western democracies. Use IPsec, SSL, ssh...

      (I'm answering based on my moldy EE and some common sense implementation assumptions, not from reading the standard.)
    • If you can explain what all these words (broadcast packets, hostile RF, and WEP) mean, I'll buy _YOU_ a beer ;)
      Oh, how I long for the days when Computers were mechanical devices run by steam engines (although I wasn't born back then).
  • It never fails... yesterday I spent $2500 on a new laptop with 802.11b and an access point, log on today and I see that I probably should have waited another few months.

    Oh well, at least when I take my system into a place with 802.11g I know that I'll still be able to get on, even if it's only 1/5 the actual speed I should be getting.

    One thing I'm looking forward to is when this new stuff hits the streets. I'll be able to pick up access points and wireless cards for my parents very cheaply as people move to the new tech and start dumping their old 802.11b pieces on ebay.

    -C
    • This is a great point. Until Thursday, I thought that the Balkanization of high-bit-rate 2.4 GHz 802.11b-like flavors would keep 802.11b the dominant standard for compatibility. But now, you're right: cheap "b" will become even cheaper, as companies hold out for "g" equipment. Why spend money on "b" today given that "g" will only cost incrementally more, if that.

  • Countering interference (Score:5, Informative)

    by Walter Bell ( 535520 ) <(wcbell) (at) (bellandhorowitz.com)> on Friday November 16, 2001 @08:15PM (#2577086) Homepage
    One of my co-workers has been following 802.11g through the standards approval process and he said that 802.11g is designed to "fall back" to using a part of the spectrum reserved specifically for this protocol if the rest of the available frequencies are congested. Although this will help little if there are several wireless networks in a dense area (cf. downtown Chicago), it will help a lot for networks like my home 802.11b setup, which starts dropping packets when somebody fires up the microwave, cordless phone, or X-10 video transmitter. These devices should not interfere with the reserved area of spectrum and thus a moderate level of network performance will be maintained.

    It just goes to show that sometimes when the FCC serves the interests of their large corporate customers (who undoubtedly begged for the reserved 802.11g frequencies for obvious business reasons), consumers benefit. Not usually, but sometimes.

    ~wally
    • As far as i know, that is not true, 802.11g opperates on the same 2.4ghz ISM band that 802.11b and many other devices use. It may be that 802.11g uses a portion of the band that 802.11b uses, but i do not think there is any allocation specificly for 802.11g
      • This is correct. 802.11b channelizes into 14 overlapping 22 MHz bands from 2.400 to 2.485 GHz (in the U.S.; fewer frequencies are available in some other countries, but all in that range). But there's no reserved "g" bandwidth.
    • That reserved band may save you from 802.11b, your cordless phone, and hopefully the XCam, but the microwave is not going to suddeny stop giving off interference ;)

      The others are legitimate signals in the same frequency band, while th emicrowave just gives off lots of noise in that general portion of the EM spectrum.

      So yes, you will see less interference. Just not when you're popping popcorn or heating TV dinners for your "watching the neighbors have sex over the XCam while wirelessly webcasting and telling your horny uncle about it on the phone" sessions.
  • Despite the recent introduction of higher-speed 802.11g products, the outlook for 802.11b continues to be strong and we forecast that the market will grow 35 percent in 2002, according to Dell'Oro Group.

  • NOT approved (Score:4, Informative)

    by victim ( 30647 ) on Friday November 16, 2001 @08:28PM (#2577123)
    The approved standard is tentative. The group will meet again next year to approve the real standard. This isn't coming to market for some time yet. register article [theregister.co.uk]

    On the plus side, it will be usable in many countries rather than just North America like 802.11a (which is in a different spectrum) and it should be easier to share the RF section with 802.11b.

    On the down side, it is in the same spectrum with 802.11b so you won't be bringing it up in parallel without interference and possible slow downs.

    I haven't seen any predicted comparisons for cost, real world bandwidth vs. distance numbers or watts/byte numbers. These will be critical for determining which standard wins acceptance in various markets. No, I'm just kidding. The marketing departments of the manufacturers will choose which we use. I am guessing 'g' because it is later in the alphabet and clearly must be more advanced, but 'a' has that whole letter-grade thing going for it. Could go either way.
    • On the down side, it is in the same spectrum with 802.11b so you won't be bringing it up in parallel without interference and possible slow downs.
      If 802.11g is replacing 802.11b in some nodes (and presumably first in those nodes sending the most data), that would increase the performance of other nodes running 802.11b in the same network since it will take less time to transmit a packet.
  • Any idea if 802.11g is going to be limited in operating radius compared to b?
  • So much for that 802.11a 30ft range crap! Now we get a REAL revision of the wireless standard. 802.11a has just been killed.
  • I'm wondering how we managed to jump from b to g. Do other versions exist (other than a,b and now g)?
  • Now that something that's 1) backwards compatible and 2) fast fast fast exists, I predict the rise of massive wireless networks. Some professionally built for official purposes, and some built for shits and grins by maniacs...

    My reasoning here is that a lot of people who are interested in the wireless network have held off waiting for a faster standard to work with. I personally can't wait to play Rogue Spear on the net from my hammock in the yard with my g4 titanium.
  • so, how long does it usually take for hardware to be made using such standards? And, can I turn my old pentium into a server that uplinks to other computers using linux? I don't like having to buy a new router box each time something fancier comes along.
  • "I think G is really going to help move along B, especially in areas where the data rate of B was holding it back," Nogee said.
  • Yes! Now I can watch my streaming pr0n right on my porch! I can now be a truly high-tech redneck!
  • I've said it before.. I'll say it again:

    2.4 ghz SUCKS in residential areas. It just takes a new generation cordless phone to knock your connection down, or someone just has to microwave dinner, and you're offline.

    I just hope the cordless phone makers don't decide the 5ghz range "is nifty" for phones when those wireless solutions come out.

    • I did some informal testing with a 2.4 GHz cordless phone and some 802.11b wireless gear and didn't see any effect at all on the wireless link when the cordless phone was used around the equipment.
      • 802.11b uses CDMA-style code division (termed DSSS, Direct Sequence Spread Spectrum), so it occupies a whole set of frequencies at once, rather than hopping around.

        802.11 (the original low speed version) came in DSSS and FHSS variants - the latter does frequency hopping, as does Bluetooth.
  • What type of range is it possible to get in the unlicensed spectrum? I think there are power output limits that prevent you from setting up high powered antennas to deliver long-range 2.4Ghz wireless Internet access. Also, how will the higher speeds affect the range and reliability of the signal (will it be as tolerant of noise)?
    • What type of range is it possible to get in the unlicensed spectrum? I think there are power output limits that prevent you from setting up high powered antennas to deliver long-range 2.4Ghz wireless Internet access.
      Depends on the terrain and other transmitters in the area. 5-6 miles is quite possible without too much work, more is do-able but often requires high towers and may requiring tweaking timing (802.11b protocol is designed for shorter distances - the time taken to cover a very long distance can cause problems with the way the software is normally designed).

      Also, how will the higher speeds affect the range and reliability of the signal (will it be as tolerant of noise)?
      OFDM should be more resilient to noise. I wonder if the spec also covers using OFDM at lower speeds (11Mbps, 5.5Mbps, 2Mbps, 1Mbps) - if so that will be an improvement over 802.11b.
  • I know I'm opening some deep wounds in the radio community, BUT,

    What about the other users of this spectrum?

    Sure people can share radio spectrum between themselves, but there's a big difference between a phone sharing with a microwave sharing with a camera, and a world-wide rollout of a million lil radios sharing with a few private weak-signal radio users.

    Yea, it's nice they at least move if they find interference, but what about the "hidden transmitter" effect? (I hear him, he don't hear me.) If I'm listening to an amateur radio satellite, and our new friends start up, would I have to move my antenna away (to keep from overloading the sat), key the transmitter, then move the ant back?

    What if I can't send out on the signal cuz it's a listening-only frequency?

    Awe heck, it'll work itself out anyways.

    Sigh.

    -Dan
    • I've sometimes wondered what kind of effect it would have on these wireless networks if I put up a 1500 Watt omnidirectional propagation beacon on 2.4 GHz. I have an FCC license that authorizes me to use the 2390-2450 MHz frequency band. If I remember correctly, Part 15 devices must accept interference from licensed users and may not cause interference to licensed users.
  • I realize this may be far-fetched, since it's supposed to be back-compatible, however...

    Is there any chance they managed to make WAP for 802.11g not a joke? I would think that would be a major selling point, in addition to the added bandwidth.
    • Yes, I meant WEP. I'm tired. Shut up.

    • Re:encryption (Score:2, Informative)

      by karlm ( 158591 )
      A feature I'd really like to see is per-host encryption keys. That way, businesses don't have to give the master network key to every guest that uses the network.



      It would really be nice if IPv6 had mandatory encryption. It just seems to me that encryption should be implememnted above the link layer if you want good security. Link layer encryption is a nice feature, but it's not the optimal solution, IMHO.



      If it isn't 3DES or an AES finalist in OCB mode (or CBC/CFB mode with a good Message Authentication Code), I'd be very skeptical. 802.11b manufacturers have shown an inability to provide good initialization vector generators, so counter modes and OFB modes are extremely suspect. ECB mode really doesn't hide message patterns well.



      Last I heard, the 802.11e working group was planning on using AES in OCB mode. Unfortunately, OCB mode is patent encumbered. On the plus side, it's really good mathematically. Provable confidentiality and authenticity with very little overhead, assuming the underlying block cipher has certain properties.


      They used to think you couldn't get cofidentiality plus authenticity without approximately doubling your processor load. But I've seen the proof to the contrary. It looks pretty convincing. One of the best things that even if someone scews up and uses constsnt IVs, you's still better off than ECB mode.

      • A feature I'd really like to see is per-host encryption keys.
        Some vendors have this on software for their 11Mbps equipment (Lucent on their ISP kit, they are picked up from RADIUS, I think that Cisco do something similar too), unfortunately it's not a standard...
    • Is there any chance they managed to make WAP for 802.11g not a joke? I don't think WAP over 802.11g would be a joke - quite a fast way to browse the web I reckon. Just use Opera and wap.google.com to transmogrify those nasty old-fashioned html pages... ;)

      Mind you, I don't think it would really be much faster than using WAP over 802.11b.

  • When I first read the headline, I parsed it as millibits. Not a really big deal...

  • Word from a mole on the inside (Score:1, Informative)

    by Anonymous Coward
    I was there. Not in the 11g meetings, but in 802.11 all the same. This is just the latest chapter in a long, very bitter and contentious battle between a couple of chipset vendors who both wanted their pet modulation scheme in the standard, and other interest groups (notably a certain 11a chipset vendor) who wanted it to DIE.

    And die it should, really. Backwards compatibility was perfectly possible using dual mode 11b/11a NICs, which will be hitting the market end of next summer. Instead, we have a three-way kludge of modulation schemes and MAC tricks to get higher than 11 Mbps in the very congested 2.4 GHz band.

    Very interesting exercise of Robert's Rules of Order, too. At the Wednesday 802.11 Plenary meeting, there was a motion to recind the PAR for the G task group. It was decided this was a technical issue, hence needed a 75% majority. This was appealed, but the meeting ran out of time. The vote would be made on Friday. The rest of Wednesday and Thursday were spent by G probably trying to figure out how not to get offed. Then, surprisingly, one of the G group's biggest foe suggested the winning proposal.

    As far as 11a range goes, of course a higher bit rate is less range (with same power). If you operated 11a at the (mandatory) 12 Mbps rate, you'd get about the same range as 11b with its 11 Mbps rate - almost same energy per bit. You want 54 Mbps? It won't go as far at 2.4 or 5 GHz.

    The only flaw with 11a at this point is the lack of "harmonization" around the world. We're still working out how to build a radio that can operate in all the authorized bands up at 5 GHz. That's the work of the 11h task group and the regulatory folks.
    • No, the biggest problem with 802.11a is that it isn't spread spectrum. Yes, I know that some adherents like to think that FH is SS, but a quick look at a spectrum analyzer will show you how unspread the signal is, full of peaks and impulses. And then there's the 5 GHz question. Four times the path loss, and unwanted gain.

      Face it, backward compatibility matters. And for the broader market, that means 2.4 GHz and something that will do "b" in a pinch. One can argue technical merits until you're blue in the face, but what really matters is the market, and if the history of POTS modem development is any guide, "g" is the future.
  • The article discuss what many have talked about on slashdot before -- that the current 802.11b standard is too slow. I for one would love to see a faster wireless device (becides 802.11a) but people need to remember that the possiblity of something being faster dosen't make it better. In my university, all connections are maxed at 10Mbit. Of course all the buildings have cat5 and could support 100Mbit, but it was decided a long time ago that the school is not interested in upgrading. I am sure many places running wireless are the same way. Although the 802.11g standard will allow for faster connections in-house, most people won't have anywere near that big of a pipe to the internet to take advantage of the faster equipment. So, everyone stop saying such bad things about 11Mbit. It's pretty fast for most things and the prices are finaly comming down. (That I will thank 802.11a/g for...)
  • What a wonderfully orgasmically sensational news headline! "802.11g Approved By IEEE 54 mb/s on 2.4 gigahertz". Thank god for geeks.
    --
    "C line noise" anagrams with "sonic edlin", and as accidental inventions go, grunting "burp" to save file seems thought-provoking.
  • is how they manage to squeeze 54Mbps out of it while still staying within the 2.4GHz ISM regulations?
  • Has anyone observed 11Mb/s on their 802.11b WLAN? Does anyone expect to observe 54Mb/s on a 802.11g WLAN? No.


    The performance of an 802.11 WLAN depends on the MAC protocol as much as the transmission rate. 802.11b employs a collision avoidance scheme in which stations wait a random period after detecting an idle medium. For .11b, this random period starts being uniformly distributed between 0 and 31 "slots", each of which is 20us long. The range increases exponentially with subsequent collisions (63, 127 etc). Even with the initial range, the wait will last on average 15*20=300us. In contrast, the transmission time for a 1500B frame is 1ms - i.e. the MAC protocol spends 1/3 of the time waiting. This is why the maximum throghput measured with 802.11b is around 6Mb/s, and why (unless they've changed the MAC) the performance of 802.11g won't get up to 54Mb/s. Unless they've also changed the MAC protocol, or its parameters, 802.11g will only be able to achieve a throughput of about 30Mb/s - 200us for the packet and 300us waiting.


    People should be more interested in end-to-end throughput, which will improve just as much with changes to the MAC protocol as with changes to the transmission rate.


    Tim

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