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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."
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?
Sometimes it's best to just let stupid people be stupid.
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
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: "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."
"Reality is just a convenient measure of complexity" -Alvy Ray Smith
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!
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.
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.
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
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