On Sun, Jun 17, 2007 at 12:51:40PM +1000, Amos Shapira wrote: FNN> I realize I'm diverting from the original question (because he's asking > about hardware he already owns) but the 802.11N looks like an almost done > deal. In a computer show a couple of months ago I saw D-Link > 802.11Nhardware which already went through one firmware upgrade to > comply with the > latest standard's draft (the standard is expected to be closed in September > 2008). > > Does anyone here have practical experience with 802.11N? It sounds like it > should be able to replace, and sometimes even improve on, current 100Mbit > "wire-full" networks.
No, but it won't replace wired networks 100%. All wireless networks have several "features" which slow them down. First they are a "bus". That means that eveyone shares the same channel. Received data has to wait for its turn to come to you. Sent data is harder. You don't have fixed times to transmit, you wait for a clear channel and start sending, Often two or more units send at once and you get a collision. If that happens you wait a random delay and try again. Hopefully, there is not another collison. This is simialr the way ethernet coax networks worked. Cell phones don't because they use very little data (for example 9.6k of data on a 1.5mb channel) and are assigned "slots" which they use. That was the difference between D-AMPS (Cell-Com circa 1996) and GSM. They both use similar technology, GSM assigns a slot when the phone starts a call, while D-AMPS assigned it as it was needed. The result was D-AMPs systems had lots of dropped calls, missed data packets, etc. Using slot assignments won't work with data networks, because most of the time you would spend waiting for your slot to come up. Throughput would be consistant, but slow. The other problem is interference. 2.4gHz is used for everything from microwave ovens, baby monitors, cordless phones, police and aircraft radar. etc. Every time one of them sends out a signal, it causes the network to "crash". My network is a slow 11mbps network, but I was able to speed it up considerably by locking the speed at 11mbps. Otherwise the normal method is to recover from a "crash" by starting a 1mbps and working up in speed until it stops working or 11mbps was reached. This took about a minute. Locking it at 11mbps, just had it stay down until the interference stopped, and then resume at normal speed. Another problem is range. My network can not be heard, nor can I hear signals from the street. I can hear a network nearby, but I don't know whose it is. It was on the same channel as mine for about 5 minutes when it was first installed, but the owner moved it quickly. If not, it will share the bandwidth with mine. :-( With the forthcoming WiMax technology, range will go from about 100 feet or so, depending upon what's in the way, antennas, etc, to several miles. You can imagine the interference you will get then. :-( Geoff. -- Geoffrey S. Mendelson, Jerusalem, Israel [EMAIL PROTECTED] N3OWJ/4X1GM IL Voice: (07)-7424-1667 U.S. Voice: 1-215-821-1838 Visit my 'blog at http://geoffstechno.livejournal.com/ ================================================================= To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
