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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."
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.
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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.
If you take a look at the 802.11 spec from 1999, you'll see a lot of stuff there that is spec'd for backwards compatibility. For example, there is the PS-Poll exchange grafted atop the normal powersave-state protocol. A lot of this backwards compatibility is at the cost of performance. A "design-from-scratch" approach could result in a much more efficient data-networking protocol design that incorporates what has been learned in the last ten years or so. However, much of the IEEE process is subject to internecine politics and hidebound practices. I am hopeful but not too optimistic.
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...
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.
- 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.