[MLB-WIRELESS] 802.11g Starts Answering WLAN Range Questions

Thu Jan 16 18:43:06 EST 2003

John, that is an excellent explanation.

Michael

John Dalton <john.dalton at bigfoot.com> on 16/01/2003 01:56:39 PM

 To:      Tristan Gulyas <zardoz at 2600.org.au>                 

 cc:      melbwireless at wireless.org.au(bcc: Michael           
          Florence/Sales/DLINK-AUST)                          

 Subject: Re: [MLB-WIRELESS] 802.11g Starts Answering WLAN    
          Range Questions                                     

> So how come it only appears to operate at 22Mbit/sec?

It could be that the diagrams refer to MAC data rate.

The 802.11a spin always seems to quote 54Mbit/s as the data rate.
These are funny numbers to the point that it could be argued
to be misleading.

54Mbit/s is based on the data rate at the bottom of the
physical layer (ie. what is actually transmitted and received).
Layered on top of this 54bit/s stream is error correction
and other such things which 'consume bits' to operate.  The end
result is that the MAC actually transmits and receives at
something closer to 20Mbit/s.  (Compared to around 10Mbit/s
under similar assumptions for 802.11b).

Ultimately the net data rate for 802.11a is not that big an
improvement on 802.11b (Depending on what you define to be big),
especially at similar ranges.

Regards
John

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