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802.11n: High Throughput, Not Just Fast Wireless
eggboard writes "Unstrung reveals that the 802.11 working group is spawning 802.11n, a high-throughput task group to work on increasing the actual data:symbol ratio in wireless networks while also boosting speed to 108 Mbps to 320 Mbps. Most people who use 802.11a, b, or g know that actual net throughput, or the real data that's carried, is a fraction of the cited rate: maybe 7 Mbps in the 11 Mbps 802.11b flavor and 25 Mbps in the 54 Mbps a and g flavors. The goal of 802.11n is to increase speed, sure, but also to increase the percentage of symbols that don't bear overhead. The bad news: they predict 2005 or 2006 for completion."
Come on - by then UWB coupled with cellular and mesh will offer those speeds. "n" should stand for "n" significant.
I think I speak for everyone when I say put egos aside, gather the best of each protocol into one protocol and make it the standard and release products for it. I think people (in general) are scared right now because they don't want to buy a product that will not be usuable in a year or two. I want my WiFi already.
Visit www.seriouslythough.com
so why hasn't this been done before? Shouldn't a good spec already be lean? We've gone through six incarnations or so of 802.11 and we still have this kludge going around? I'm sure its not as easy as I'm making it out to be, but I would get fired if someone could take my spec and cut out this much overhead from it. The time to spend the four or five years crafting a good symbol set is before the thing goes public, not after.
If you want highspeed wireless networking just buy some of the at&t microwave bunkers. As a bonus you can have huge w/lan parties and microwave your food free of charge at the same time.
Checking out my form of escapism.
Favorite quote from the article:
802.11 Specification letter suffix: O
What it does: Not being used, because it looks confusing.
In all seriousness, this would be an incredibly useful technology--802.11b at it's current real speed is quite unusable for transferring files of significant size. However, I have to admit that I'm tired of seeing a Baskin-Robbins offering of wireless flavors...802.11g is a noble effort at standardization, but backwards-compatible technology is a must. I can't afford to have twenty 802.11g, 802.11n, 802.11-whatever cards sticking out the side of my notebook/PDA/random useless all-in-one wireless device of the week.
I'm glad someone is focusing on the overhead and efficiency of the standards and not just trying to get something out there with a big unrealistic marketable speed. I guess comparing advertised Mbps on wireless devices could be like comparing MHz for CPUs by different companies.
This has to do with information theory, source and channel coding and modulation.
It'd be nice if these people standardised on a framework that can be combined with various coding and modulation schemes, in a modular sense, instead of creating 802.11xyz groups every now and then...
Guess marketers and managers (ie The Incompetent at best, The Illiterate as per usual) have taken over from the engineers.
/. Where the truth
Have they taken into consideration that they might run out of letters at some point? ..especially if we skip from g to n.. there's some cool letters in there...
Throughput on 802.11b networks is actually only around 3-4 Mbps in optimal conditions, less than 50% of the theoretical maximum.
They might as well just give up and start saying "Oh, you don't want 802.11[n] anymore - you should throw away all your hardware and get 802.11[n+1] instead, since it'll be so much better! No, really!"
In Soviet Rush, today's Tom Sawyer gets high on you.
I just wanted to point out that if we accepted 11Mbps and 54Mbps as the speeds of 802.11b and 802.11a/g then we would have to call regular fast ethernet 200Mbps. 802.11b is 5.5Mbps full-duplex and a and g both are 27Mbps full duplex. It is true that the radio signals are capable of carrying 11 and 54 respectively, but half of this bandwidth is dedicated for each direction, so that the MAXIMUM one-way speed you can achieve with 802.11a/g is 27Mbps. This means that if they're hitting real-life numbers of 24Mbps (I doubt it) of data throughput, then they're doing really well - about 88% of theoretical. That's as good as you can really expect from wired networks, in terms of throughput to bandwidth ratios.
I did not design this game/I did not name the stakes/I just happen to like apples/And I am not afraid of snakes-AniD
I think you're a bit confused about how the ways are going. At any given time, they're developing several different specs for wireless communication. Some of these, such as the publicized 802.11a, b, and g are hardware-side, meaning they have to deal with the way these things are actually transmitted. Others are more software-side, meaning they have to do with encrypting data and whatnot. Furthermore, all of these (except for a few earlier strange circumstances such as 802.11a) are backwards compatible.
In short, the hardware you buy today WILL be usable in a year or two. It just won't be the fastest, bestest thing on the market. Think of it as Moore's Law translated to wireless communication.
Maybe they should concentrate on approving the 11g standard first.
Just to comment on the "users of 11g" stuff: The implementations you are currently seeing in the shops are based upon more or less early *drafts* of the standard. The fit will really start hitting the shan when people start combining devices from different manufacturers: Incompatibilities range from different modulation schemes (TI) over incompatible MAC protocol elements (dataset identifiers in AP capabilities) to legacy support (some old legacy devices refuse to associate with APs supporting the new modulation modes due to excessive supported-rates-list lengths).
The origin of the slow effective transfer speed by the way is the MAC layer timing. Each information frame is transfered independently and ACK'ed by the receiving station on MAC layer -- the time delays in these frame exchanges take up enough time to reduce the effective transfer rate to about half for the 54Mbps mode. Besides QoS 11e will introduce burst frame acknowledge which should improve the situation considerably and therefore the new modulation schemes may actually make sense.
Depends verry nuch on the environment. You'll get 60% in the countryside while 20% in crouded spectrum metropolitan area might be a good asumption.
http://ebgp.net/ccc/
If you can find an access-point that will do 802.1x properly with rolling keys, you are in great shape, even with RC4 WEP. The WEP attacks that have been published exploit a vulnerability with poorly-chosen IV values, and if enough encrypted packets are captured, the keys can be inferred. But, if you rekey on a frequent basis, and use a "modern" implementation of WEP which avoids the weak IV values, then you will be fine. Unfortunately, I don't know which SOHO access-point devices currently support an optimum 802.1x implementation. On the client side, Windows XP SP1 does it right, and I believe that Meetinghouse has client implementations for Linux and Mac OSX.
- Technically we call it "100baseT Full Duplex"
- The 100 refers to 100 bits/second as a maximum channel capacity, not the maximum transfer rate between two hosts. it takes multiple hosts using the channel at the same time to saturate the channel.
- Half of the bandwidth of 802.11b is NOT set for " each direction". The full amount can be used for either direction.. it's half duplex. Further, the 11mbps refers to the radio channel, not any " direction".
- Full channel usage happens with multiple hosts, not with only two. with two hosts.. just like ethernet, but the delays and wait times are larger, adn there is more protocol overhead, due to the lack of collision detection.
As long as you have multiple access points and put them on different channels it should work.
For virtually all consumer applications, 60% (or less!) of 802.11b's throughput is an ample plenty.
Why? Because the VAST majority of data they schlep goes through their broadband provider on the way to or from the Internet, where they don't get anything even APPROACHING 5 Mb/s. The line out of the house is the bottleneck in my home and in many, many other homes.