Slashdot Mirror
Introducing 802.11s - Wireless Mesh Networking
ikewillis writes "Intel has introduced a new wireless networking standard called 802.11s. This standard utilizes a mesh topology, allowing for fully self-configuring networks where each node can relay messages on behalf of others, thus increasing the range and available bandwidth with the number of nodes active within the system, versus the point-to-point structure of existing WiFi networks. This will radically transform WiFi hotspots, allowing the geographical area and available bandwidth on the network to scale with the number of participants."
You could also combine the two. Create a short range wireless LAN using mesh technology. And connect those short range WLAN's using WiMAX.
That depends ... if your city happens to be somewhere where it's not banned (ie. not in the US) then things will be good :-)
http://computer.howstuffworks.com/wireless-network 2.htm
Check out the whole article to find out more about the various 802.11x standards (excluding the new 's' one).
What do the letters mean?
"Task groups within the 802.11 WG enhance portions of the 802.11 standard. A particular letter corresponding to each standard/revision, such as 802.11a, 802.11b, and so on, represents the different task groups. For example, Task Group B (i.e., 802.11b) was responsible for upgrading the initial 802.11 standard to include higher data rate operation using DSSS in the 2.4GHz band."
From 802.11 Alphabet Soup.
to tell the truth, 802.11a, 802.11b, 802.11c, 802.11d, ... exists, but some are less used (and known) than others.
More info (with explanations) here
I recall the Wifi band is somewhere around 2.4GHz, which also happens to be the band absorbed by water. You know... like in your microwave oven... wave absorption heats the water, hence the "cooking".
Just an FYI, WiMAX runs across both licensed and unlicensed bands.
I recall the Wifi band is somewhere around 2.4GHz, which also happens to be the band absorbed by water. You know... like in your microwave oven... wave absorption heats the water, hence the "cooking".
... don't you trust the FDA and FCC ...
Radiation is the square of the distance from the emitter. More likely the barrista will get cooked than a customer with less exposure, unless they put the 802.11s devices outside the coffee area, or embed them in the fake wood supports for the coffee place.
You act as if humans were made of 98 percent water
-- Tigger warning: This post may contain tiggers! --
The other problem would be the number of hops required for long distance. If 1,000 hops are needed to go from NY to CA, what would the latency be?
The performance will always be less than an "every AP has its own landline" topology, but networks will be much easier to build (and perhaps simpler to maintain).
As for the details of what has been discussed so far in the 11s task group, anyone can sign up for an account at 802wirelessworld, and obtain access to all the documents submitted for consideration to the task group so far. (Once you register and login, a link for Documents shows up under 802.11 WLAN WG on the left of the page.)
Various usage scenarios have been considered, from the scale of the home ( a few devices) to larger scale community meshes. The standard will work on any "mesh-aware" point, which may be an AP or a client device. It will likely run at layer 2 (below the IP layer) and provide a standards based mechanism for multi-hop access to a wired gateway (or "mesh portal" as they refer to it).
Capsule summary--the privately-owned WLAN infrastructure should bypass and where possible replace the wired corporate-owned network infrastructure. There are three main facilitating aspects:
Freedom = (Meaningful - Coerced) Choice != (Speech | Beer^2), and sad sock puppets' bad mods avail them naught.
However, what I read on the IEEE Web site recently made it sound like merely a self-configuring version of WDS (so that only access points participate in the mesh).
Yes, that's basically the idea behind the 802.11s Task Group-- but the phrase "self-configuring version of WDS" really doesn't quite go far enough in describing the concept. It's sort of like describing the Internet protocol as a "self-configuring version of frame-relay". Probably not helpful.
Wireless mesh networks are multi-hop in a way fundamentally more complicated than the simple access point and a bunch of associated stations. They'll have to run a routing protocol and forward from mesh node to mesh node in an efficient and secure way. They'll have to be robust in the face of individual node failure. They'll have to support stations roaming securely between nodes in the same mesh network. It's a whole lot more then just self-configuring WDS.
Folks shouldn't get too excited about this standard. There are a lot of obstacles to making large multi-hop 802.11 networks as efficient as similarly wired topologies. The 802.11s task group isn't chartered with fixing the problems in the MAC layer that keep multi-hop networks from scaling up to very large meshes.
What are the problems? The big one is that they have a profoundly negative effect on TCP fairness. Next up is that multicast is just horrible. Even on regular 802.11 infrastructure networks, it's just horrible. On mesh networks, don't be surprised if it's even worse.
jhw
What happens when a node goes down between several other nodes and the other nodes are now out of range of each other? The network will split and the result will be two seperate networks that are unable to reach each other until the connecting node is up again.
(Assuming they did it right...)
If the connecting node that dies was the ONLY PATH LEFT between you and the guy you want to talk to, yes it splits.
If there is another path available you reroute.
Just like when an earthquake or flood takes out highways and bridges.
Just like the internet used to be - and to a large extent still is in the core.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
You might want to check this out... there are practical problems with large diameter networks. Some of the problems lay at the MAC layer (i.e. in the specs), so solving them probably requires radically new thinking.
The problem with the rosy view is that most real study has been done in simulation. There are not a lot of papers detailing real, large scale testbeds (with a literal handful of exceptions).
And the airport is nice, but I wouldn't want to participate as a mobile node with that card without an energy-aware network stack - I gather it is one of the worst in terms of power efficiency.
But if you've ever had a roommate who runs p2p apps with uncapped upload bandwidth, you'd know why sharing a 'net connection sucks. It only takes a single computer on a cable modem based lan to make the connection unusable for everyone else.
Apps like edonkey/emule and limewire will gladly use every bit of upstream bandwidth you have, bringing pings to sites like google and yahoo up to 1000+ ms for the rest of the lan. And of course, the majority of people are do not know that they should limit their apps' network usage, much less how to do so.
I don't know about you, but I'm not interested in sharing my internet connection with people who aren't computer literate enough to be 'good neigbors'.
Yes, but how often are you really connecting to a server within a couple hundred feet of where you are sitting. While correct I think your response isn't quite relevant.
However, I think the initial assumption, that a mesh network is necessarily broadcast, is simple incorrect. One can use broadcast packets to collect routing information and then implement a point-point network. Well as point to point as one can get using wireless networks, i.e., your packet needs only be replicated by one host amoung your neighbors. After all to some extent any wireless network is broadcast.
If you liked this thought maybe you would find my blog nice too: