Adam "TidBITS" Engst and Glenn "WiFi Networking News" Fleishman have put together a great article that looks at the new 802.11g equipment, which interoperates with older WiFi gear, but can also support new, cheap wireless cards at 500% of WiFi speeds. The most interesting part, for me, was this info about multipath:
One of 802.11g's big advantages over 802.11b is that it better handles the inevitable signal reflection. Radio signals bounce off different pieces of matter–floors, metal, even the air around you–at different angles and speeds. A receiver must reconcile all the different reflections of the same signal that arrive at slightly different times into a single set of data. 802.11g (like 802.11a) slices up the spectrum in a way that enables receivers to handle these reflections in a simpler but more effective way than 802.11b.
There've been many contexts in which I've seen bad multipath scatter — it's evidenced when you run an application like MacStumbler and see dozens of instances of the same network — usually on crowded trade-show floors with lots of booths or in offices with twisty corridors. It really kicks the hell out of WiFi signal: this is pretty encouraging. Also interesting is this sidebar on 802.11a, which I'd always dismissed as a failure due to its incompatibility with older WiFi gear:
Because 802.11a has 12 distinct channels that can be used without interference in the same place, it offers an advantage for scenarios in which avoiding interference is important. Likewise, the four channels reserved in the upper end of the 5 GHz band for 802.11a outdoor, point-to-point use can employ higher power levels, which may provide a better throughput than 802.11g in the same circumstances.
(via Apple Airport Weblog)
