Wireless G/B interoperability confusion

[CuriousMark]

I have received confusing answers to questions about operating a mixed mode wirelessG home network with both G and B adapters. My questions relate to network speed. Linksys tech support told me that only the B adapters will communicate at 11Mbps and all the other G apapters will communicate at the full 54Mbps. D-Link tech support said that the whole network would slow to B speeds. Some forum posters on populare magazine site forums agree with Linksys and others agree with D-Link.

Is there a definitive answer out there?

Is it vendor specific? Do D-Link products all slow to lowest common denominator while Linksys products somehow adapt to the different modulation schemes so that all connections use their best possible speed?

I did an experiment with a D-Link system and a G connected computer did seem to slow about 25% (from 800 to 600 kBps for a file copy of compressed files) when I linked in a B USB adapter on an A/V component. So it seems the D-Link guy is right about his own hardware. What about the other guys? If they are right I would expect it to be a big selling point that doesn't seem to get much mention.

Curiouser and curiouser.

[Phoenix]

First off, anytime you add a computer to the network, thoughput for an individual computer will slow down due to the fact that they are sharing the bandwidth. It is much more drastic when a B radio is added to a G network (because the B device is so much slower than the G, the B device will "hog" the bandwidth). Many of the chipset vendors have enabled a technique called packet bursting to mitigate some of this slow down in mixed B/G networks.

For more info: http://www.conexant.com/servlets/DownloadServlet/102392a.pdf?FileId=1657

But to answer your question, both the Linksys people and the D-Link people are correct. The G adapters still communicate with the AP at 54Mbps, but the whole system throughput will slow way down to almost (but not quite) B speeds.

[CuriousMark]

Thanks. Your link led me several places, including a few google searches that finally explained it all to me. Whenever a B device is linked, all G transmissions start with a short burst of transmission using the B modulation scheem to tell any B devices out there to shut up for a while and not interrupt the G transmissions that the B devices cannot see. This adds a little overhead to all G transmissions and probably accounts for the 25% slowdown I saw in copying files from a G connected computer to a hardwired computer. The G transmissions were running at full rate once they got going.

I appreciate your answer.

Mark