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Pat Ellison wrote: >>- my personal legal record (within the +20dBm limit) is 50km with 802.11g >> using 1.2m dishes and a 25dB 2.4GHz RX-preamp. > > > That's a good haul! 50km I don't think I ever heard of that distance. > What's your illegal record? ;) ha ha http://www.bbwexchange.com/publications/newswires/page546-1086045.asp 802.11b, ok. > > -Pat > I am not connected in any way to any policing authorities! > > -----Original Message----- > From: Daniele Guazzoni [mailto:daniele dot guazzoni at gcomm dot ch] > Sent: Tuesday, August 17, 2004 6:17 PM > To: m0n0wall at lists dot m0n0 dot ch > Subject: RE: [m0n0wall] Wireless g 54M > > > Out of topic but... > > my 2 cents about wireless: > > About bitrate and throughput: > - with 802.11b you have a RF bitrate of 11 Mbps wich means a pure IP > throughput of about 4 Mbps. > - 802.11g provides 54 Mbps of RF bitrate, also about 22 Mbps of IP > throughput. > - 802.11a has about the same properties of the "g" standard. > - some chipset maker have introduced proprietary (but backward compatible) > pseudo-standards like 22 and 100 Mbps > This is obtained by grouping several frame together before RF encoding, > thus reducing the overhead. > Practically you get more "speed" only if you can fill up frames and this > is not always the case. > - Of course if you are 500m apart from your AP you will have more errors, > retries and therefore less throughput. > > Technology and Compatibility: > - 802.11b and "g" works on 2.4GHz and g is backward compatible with b > - 802.44a is on 5GHz and compatible with itself. > - Depending on your local low you may be allowed or not to use 802.11a for > outer links (not inside a building). > > World standards: > - I know in US you can use more TX power than in Europe (ETSI limit to > +20dBm EIRP = 100mW) > > Range: > - the "g" standard use more bandwidth then "b" and is therefore less > sensitive. > For instance Linksys specs "b" with -80dBm and "g" with -65dBm. > - since "a" and "b/g" are on different frequency ranges, radio propagation > may cosiderably differ. > - my personal legal record (within the +20dBm limit) is 50km with 802.11g > using 1.2m dishes and a 25dB 2.4GHz RX-preamp. > The link provided 19Mbps of IP thoughput. > > Settings and tips: > - on most "new" AP for 802.11g you can set the operating mode to "g-only" > thus you switch off the "b" compatibility. > This ensures that no one can tear down your AP to "b" speeds. > - Be sure you upgrade the firmware !!! > There may be huge difference between a "g-draft" and the standard release. > - Choose carefully the emplacement of your AP and antennas. > Run some tests, for instance the distance between antennas and walls is > critical. > A move few cm (or inches) can act as a wonder. > - Some AP allows to set the TX power (either per default or via "hacked" > firmware) > Also the default TX power varies: most AP in europe are set to +15dBm, > other to +12. I also saw a +8. > 6dB less means about half the distance !!! > - I you cannot "push" more out of your AP, get external antennas. > > Daniele > > -----Original Message----- > From: Fred Wright [mailto:fw at well dot com] > Sent: Dienstag, 17. August 2004 22:41 > To: m0n0wall at lists dot m0n0 dot ch > Subject: RE: [m0n0wall] Wireless g 54M > > > On Tue, 17 Aug 2004, Pat Ellison wrote: > > >>Now that is my problem.... I've been so happy with this system that I >>neglected to learn anything about the A/B/G...etc systems. Not I'm >>forced to become a quick study.. > > > One thing I don't know is whether the A/B/G cards can run A simultaneously > with B/G. My guess is that the answer is no, since it's *very* difficult to > design something that can send and receive at the same time through the same > antenna, even in different frequency bands, and sharing the transmit/receive > scheduling between the two would get messy, if it's even possible. > > On Tue, 17 Aug 2004, Chet Harvey wrote: > > >>Just a side note, I am always curious as to why people think they need >>such fast rates like 75 to 100mbps. Most businesses I see have 512 or 768 > > pipes. > >>Some go crazy and get 10mb pipes so unless you are moving A LOT of >>data internally I just dont get it. I'd rather have range and signal >>strength over high transfer. As signal strength drops so does transfer. > > > I presume the "512 or 768 pipes" you're talking about is for the WAN. I > can't imagine anyone wanting a LAN that slow. It's not even that fast for a > WAN; I have 6M/600k DSL at my *house*. :-) > > Anytime you start doing something ike file sharing, it's almost impossible > to have too much bandwidth. Or using VNC, though that's mostly VNC's fault. > :-) VNC is annoyingly slow over Gb Ethernet. > > On Tue, 17 Aug 2004, Robert Staph wrote: > >>From: "Fred Wright" <fw at well dot com> >>Sent: Monday, August 16, 2004 3:53 PM >> >> >>>1) How poor the range usually is for G (*much* shorter than B with >>>the same equipment). >> >>Actually I've found my Linksys WAP54G to have superior range than my >>Linksys BEFW11S4. I can get 36M out to where the B signal was >>dropping to 5M. I > > > Well, I did say "same equipment". :-) > > >>>2) How the presence of a single B station causes all the Gs to drop >>>down to B. I'm not sure it even needs to be an "authorized" B >>>station to have this effect. >> >>I have a B AP about 50-60 feet from my G AP, no issues getting beyond >>B speeds when connected to the G AP. Different SSID's and channels (1 >>and 6), one WEP one not, one does its own DHCP other doesn't, two very >>different configs. However since they do not share a SSID, I would >>think it possible a B station and G station using the same SSID and >>config might cause the G client to dumb down and not talk G (or if the >>AP's are very, very close; or both are passing as much traffic as they can > > handle). > > I wasn't referring to independent networks, but to the "upward > compatibility" feature of G with B. This is in the same sense that 66MHz > PCI is "upward compatible" with 33MHz PCI, i.e. plug in a single 33MHz card > and everything switches to 33MHz. Similarly, *on the same network*, the > presence of a B station drops everything to B speeds. > > On Tue, 17 Aug 2004, Pat Ellison wrote: > > >>I know what you mean.. it's like a family going to Circuit City for a > > "New" > >>computer.. >>"So sir, what are you looking to do with your new computer?... Well >>the wife plays Solitaire.." >>so the salesman needs to make sure that the computer is suited for his >>needs.. "oh well then, We have this 3.2 Ghz Intel with Hyper >>Threading(tm)..." > > > Hey, don't knock HyperThreading. Recently a case came up where Linux needed > HT just to be able to output text to the console at a reasonable speed. :-) > > Fred Wright > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: m0n0wall dash unsubscribe at lists dot m0n0 dot ch > For additional commands, e-mail: m0n0wall dash help at lists dot m0n0 dot ch > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: m0n0wall dash unsubscribe at lists dot m0n0 dot ch > For additional commands, e-mail: m0n0wall dash help at lists dot m0n0 dot ch > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: m0n0wall dash unsubscribe at lists dot m0n0 dot ch > For additional commands, e-mail: m0n0wall dash help at lists dot m0n0 dot ch > |