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."

Comments

Goofy letters

[Fisch2]

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).

Re:s?

[Xeo 024]

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.

Re:s?

[Evan Meakyl]

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

WiMAX runs over unlicensed freqs too

[mveloso]

Just an FYI, WiMAX runs across both licensed and unlicensed bands.

Making hardware do what people expect it to do

[j1m 5n0w]

Have you ever installed one wireless access point, and wished you could install a second, within wireless range of the first, without running a second cable? Most access points can't do that, even though most people expect them to be able to before being told otherwise. Mesh networking would enable this sort of networking, and much more.

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).

Re:A clarification and question

[e271828]

Actually, Intel has not yet issued a formal proposal to IEEE, but since they are playing a key role in the 11s task group, they will almost certainly be issuing their proposal in response to the call for proposals that just went out in late January. Proposals are due June 15th, I believe.

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).

Re:A clarification and question

[j h woodyatt]

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.

Re:Sounds great but unreliable?

[Ungrounded Lightning]

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.