802.11G slowdown with B clients attached (mixed mode)

[Esbil]

I've noticed (and read it referenced in a number of WAP reviews) that B clients attached to a G network will slow the entire transfer rate. When I did some searching, all I came up with was a reference to CTS Protection Mode -- but that's disabled on my router/WAP.

Anyone have some good white paper info on why the B client slows traffic when the WAP is in mixed mode?

[edit] meant to say that CTS is disabled on my router [/edit]

 

[RBBRMADE]

I believe that when a 'B' client connects, all wireless connections become 'B' speed.

 

[JackMDS]

It is not a matter of setting; early 802.11g use to be slow down with the presence of 802.11b signal.

If intolerable, and can not improve by flashing the newest firmware available get new hardware.

:sun:

 

[Esbil]

It's a relatively new piece of hardware (latest WRT54G version).

I've been doing some reading/searching this morning and it seems to be the general concensus that there will always be some overhead regardless of hardware because of the way the two different types (B & G) communicate with the WAP. If that's not the case anymore, I'd like to see a link/white paper that describes how it gets around the limitation (without using multiple radios that is).

 

[spidey07]

you can't get around it AFAIK.

overall data rate will slow for all clients if there are b clients on the access point. You should be able to tell your AP to do G only if it is a concern.

 

[ScottMac]

There's no way around it.

The issue is that since "b" and "g" use different encoding & modulation (even though they are on the same channels / freqs) and can't "see" each other, the AP has to go into a mode where it explicitely controls who talks when (so that the g and b clients don't talk at the same time).

That process slows the whole deal down.

It does *not* drop everyone to 'b' mode. The throughput reduction for the g clients is ~25-35% as a rule, depending on how many b clients, and how much traffic they produce or cause (i.e., response from a web server).

FWIW

Scott