[ previous ] [ next ] [ threads ]
 
 From:  Alex Sandini <asandini at blue dash chip dot be>
 To:  Pat Ellison <pat at zbit dot net>
 Cc:  daniele dot guazzoni at gcomm dot ch, m0n0wall at lists dot m0n0 dot ch
 Subject:  Re: [m0n0wall] Wireless g 54M
 Date:  Wed, 18 Aug 2004 22:56:25 +0200
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
>