Slashdot Mirror
802.11g Approved By IEEE 54 mb/s on 2.4 gigahertz
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."
more info at eetimes
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?
HIV Crosses Species Barrier... into Muppets
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.
"Reality is just a convenient measure of complexity" -Alvy Ray Smith
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
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
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.
802.11c
802.11d
802.11e
802.11f
802.11h is already under development!
Disclaimer: I really don't know what any of this stuff is, I just searched on google.
The man who trades freedom for security does not deserve nor will he ever receive either. - Benjamin Franklin
FWIW, Atheros claims 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.
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.
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.
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.)
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.
Mea navis aericumbens anguillis abundat
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.
Copyright Violation:"theft, piracy"::Anti-Trust Violation:"thermonuclear price terrorism"<-Overly dramatic language.
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....
.11g. 802.11a uses 5 GHz. Neither uses 900 MHz, of course.
802.11b uses 2.4 GHz, as does