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New Member

DSSS and 33Mbps

hello:

i was reading through a cisco wireless presentation and found a slide that said that since dsss uses non-overlapping channels (3) you have a combined rate of 33Mbps (when using 802.11b) if you use 3 separate APs. "Total Bandwidth=33Mb!!!" it says. I see no way that this can happen. I understand i might be able to increase the number of users without having interference, but certainly not increase BW (speed in the cell).

Can anyone shed some light on this? Maybe I took the text the wrong way or something.

Thanks,

carlos.

2 REPLIES
New Member

Re: DSSS and 33Mbps

If you put the 3 APs close to each other, the cell coverage will be roughly the same. And if you configure each one to use a different non-overlapping channel, there will be no interference between them. So, you'll get a combined rate in the cell of 33 Mbps (3 x 11 Mbps) to share between the clients of the 3 APs. Each client will communicate at no more than 11 Mbps, but you will be able to put 3 times the number of clients.

Think of it as using 3 hubs to serve the clients in an Ethernet wired environment. The total bandwidth could be seen as 30 Mbps. Just a little tricky ;-).

As I see it, the problem could arise with the association between the clients and the APs. You can configure one third of the clients to prefer AP#1, another third to prefer AP#2 and so on. It doesn't seem to be a good solution. Or, you can rely on the inherent load balancing mechanisms that makes a client, according to Cisco, select the best AP to associate with.

Has anyone deployed a scenario like this? Do the clients distribute evenly with respect to the APs? Or do they begin to disassociate and reassociate frequently?

Javier

New Member

Re: DSSS and 33Mbps

thanks, javier...it seems i got it right all along. really, i just wanted to know if i missed something or if this was more like...a trick (to paraphrase you).

no, this scenario i have never seen deployed.

c.

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