Use Multiple Channels for Faster Wireless Networking

icypyr0 writes "The Register reports: 'Current dual-mode 802.11 'a' and 'b' access points use only one of Wi-Fi's 11 RF channels at a time, with users taking turns. The Engim chipset can 'see' all 11 at once, and can use the three non-overlapping ones (1, 6 and 11) in parallel, increasing total throughput and enabling features to be incorporated in silicon that are usually implemented, at extra cost and performance degradation, in software.'"

Comments

Re:that's 110 kilometers...

[zerocool^]

I don't know about across the english channel. At some point, you pass the horizon, where you can't go any further due to the curvature of the earth. I was pretty sure that level was around ... either 50 or 100 miles, I don't remember. Can you see France from Kent?

~Will

overlap?

[StateOfTheUnion]

Are 1,6, and 11 the only channels that don't overlap?

Tragedy of the commons forming!

[LostCluster]

Of course, if you use the entire 2.4 GHz band, your neighbor can't. That's part of the reason why we have multiple channels to keep everybody from running into each other time. I highly doubt this group has bothered to test what kind of downside there is for a standard-issue WiFi setup operating 100 yards away.

Re:Tragedy of the commons forming!

[Anonymous Coward]

Just log in to their default-passworded APs and set them to use channel 1. Then set yours to use channel 6. Let them deal with packet loss.

As if Wi-Fi space wasn't crowded enough already...

[misleb]

I've been in places where you can't find a free channel because there are too many other people using Wi-Fi in the area. Now we're going to have individuals using ALL of the non-overlapping frequencies? That really sucks. As far as I am concerned, Wi-Fi as we know it will not go very far. There is just no way people are going to be able to share such a limited frequency spectrum... not in densly populated areas, anyway. I'll take good ol' reliable wires any day. Wireless is overrated.

-matthew

Interference

[Ctrl-Z]

This type of idea is not new, and I have seen it in wireless routers/nics for months. The primary drawback is that if you are using up all those channels, your neighbour's wireless network won't have anywhere to go. Conversely, if you are that neighbour, it wouldn't make you very happy.

I consciously decided against buying something like this for that very reason when I bought my wireless hardware, even though the cost difference was negligible.

Re:What about 802.11G?

[timeOday]

If I understand correctly, you're saying 10base2 is shared while 10baseT is not? That's not true. Both wire types are used for ethernet, and both are shared. Ether way, collisions aren't that big a deal after all, see the classic reference:

Ethernet works in practice, but allegedly not in theory: some people have sufficiently misunderstood the existing studies of Ethernet performance so as to create a surprisingly resilient mythology. One myth is that an Ethernet is saturated at an offered load of 37%; this is an incorrect reading of the theoretical studies, and is easily disproved in practice. This paper is an attempt to dispel such myths.

...

Figure 10 shows excess delay , a direct measure of inefficiency. It is derived from the delays plotted in figure 8. The ideal time to send one packet and wait for each other host to send one packet is subtracted from the measured time. The time that remains was lost participating in collisions. Notice that it increases linearly with increasing number of hosts (offered load). When 24 hosts each send 1536-byte packets, it takes about 31 milliseconds for each host to send one packet. Theoretically it should take about 30 mSec; the other 1 mSec (about 3%) is collision overhead. Figure 4 agrees, showing a measured efficiency of about 97% for 1536-byte packets and 24 hosts.

The upshot is that ethernet can carry very close to its rated capacity even if there are a lot of hosts and a lot of collisions. (Of course nowadays we tend to use switches instead of hubs anyhow, but that's not a at all inherent in 10baseT wiring).

Whether wireless will work quite this well, I don't know.

Noooooooooo!

[Jahf]

This will destroy wireless ISP communities.

I already have only -2- channels that I can reliably use in my house without interference. Every other channel is in use for ISP access in our community or gets interference from cordless phones and microwaves.

If you want more throughput, use different frequencies. Even if they are close to 802.11b/g that is better than going into the already established spectrum.

Yes, I know that this is not mandated or regulated space, so there is not much I can do to enforce my needs. However unregulated waves only work if people make an effort to play well together.