Sorry Jim, I was but specific enough it is not the standard that is the problem but the chip makers read i.e. http://www.vnunet.com/analysis/1140873
Martin > > The issue is not that the implementation is messed-up (switching > modes), but rather that the AP must clear the air (via > promiscuous CTS) before sending any OFDM-encoded frame. > > If it doesn't, then the B units in the area might not set CCA, and, if > they send a frame while either the AP or one of its > 'G' clients is attempting to receive a frame, interference will result. > > You get 'mixed mode' as soon as a single 'B' unit is associated, even > if its not sending any traffic. > > 802.11a and 802.11b were ratified at the same time (Sept 1997). > 802.11g came along later. > > Jim > > On Jun 27, 2004, at 9:23 AM, [EMAIL PROTECTED] wrote: > >> There are wireless units that supports both 5.8 and 2.4 at the same >> time >> those are the dual-band units, i.e. >> http://www.linksys.com/products/group.asp?grid=33&scid=35 >> >> As Larry said, mixed mode is used if u have both G and B units in use >> on >> the same AP, the reason that G mode will not support B units, is that >> B units do not understand the OFDM modulation used by G (to boost >> performance to 54 Mbit/s). B uses CKK and Barker code. But in mixed >> mode >> the chipset uses different modulation for each session, this is not >> very >> well implemented so if you have G and B units on the same AP, the G >> units >> will take a big performance hit because of the switching between OFDM >> and >> CKK. >> >> Martin Madsen >> >>> Your wireless router can only transmit/receive on one frequency >>> band... >>> thus you cannot mix 2.4 GHz B and G with 5.8GHz A... A stands alone, >>> and >>> I think it has gone the way of the Betamax. >>> Your router may be allowing you to set it for "B only" or "G only", >>> and >>> I am guessing mixed mode would be used if you have some B and some G >>> enabled clients on your network. >>> Larry >>> >>> -----Original Message----- >>> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] >>> Behalf Of car val >>> Sent: Saturday, June 26, 2004 6:11 PM >>> To: [EMAIL PROTECTED]; [EMAIL PROTECTED]; >>> [EMAIL PROTECTED]; [EMAIL PROTECTED]; [EMAIL PROTECTED] >>> Subject: [SOCALWUG] the "A" protocol >>> >>> >>> Hi SOCALWUG Membership, >>> >>> I'm missing something?? >>> >>> I know the "B" was the first protocol transmitting at >>> 11Mbit/s freq 2.4MHz >>> >>> Protocol "A" was second transmitting at 54Mbit/s >>> freq 5.0 MHz >>> this was more for commercial use, and was transmitting >>> freq 5.0 MHz had less interference with wireless >>> phones (2.4 Mhz) >>> >>> then "G" came along at 54Mbit/s freq 2.4MHz >>> this protocol was able to pick up both "B & A"?? >>> >>> >>> my question, my Linksys wireless Router (WRT54GS) >>> >>> has wireless settings for transmitting at >>> >>> 1) Disabled >>> 2) Mixed >>> 3) "B" >>> 4) "G" >>> >>> >>> shouldn't it be as follows?? >>> >>> 1) Disabled >>> 2) Mixed (would be "G") >>> 3) "B" >>> 4) "A" >>> >>> Second Question, I never see Wireless "A" AP, or >>> Router advertised??, do they exist?? >>> >>> TIA >>> carval >>> >>> >>> >>> >>> __________________________________ >>> Do you Yahoo!? >>> New and Improved Yahoo! Mail - 100MB free storage! >>> http://promotions.yahoo.com/new_mail
