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b or g for best distance?

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  • Wireless Network
  • Internet Connection
  • Wireless Networking
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April 11, 2004 5:19:47 PM

Archived from groups: alt.internet.wireless (More info?)

I'm setting up a wireless network in a two story brick house.
Speed is not a major concern as the network will be used mainly for sharing
a dsl internet connection and not file sharing between the 4 computers.
Would wireless "b" or "g" be the best option for maximizing distance and
penetration through brick walls?

More about : distance

Anonymous
a b F Wireless
April 11, 2004 5:19:48 PM

Archived from groups: alt.internet.wireless (More info?)

On Sun, 11 Apr 2004 13:19:47 +0800, "John" <me@mine.com> wrote:

>Would wireless "b" or "g" be the best option for maximizing distance and
>penetration through brick walls?

they are the same from a radio perspective and g falls back to b
standards at weak signal levels (long distances)

Phil
Anonymous
a b F Wireless
April 11, 2004 10:50:44 PM

Archived from groups: alt.internet.wireless (More info?)

In article <glci70p9s2tqe5ba6c65vor92gkeepr2j6@4ax.com>,
Phil Thompson <cynical_observer@hotmail.com> wrote:
:o n Sun, 11 Apr 2004 13:19:47 +0800, "John" <me@mine.com> wrote:

:>Would wireless "b" or "g" be the best option for maximizing distance and
:>penetration through brick walls?

:they are the same from a radio perspective

They are NOT the same from a radio perspective: they use different
waveform encodings that have different properties when they encounter
situations that would lead to multipath.

http://www.commsdesign.com/story/OEG20030114S0008

: and g falls back to b
:standards at weak signal levels (long distances)

That's not correct. If you look at the symbol rate specs of
combined 11b / 11g products (such as a Cisco AP1200), you will see
that they have different symbol rates at long distances. Notice for example
in the chart at http://www.54g.org/standards.html that 11g can use
the symbol rates of 9 and 6 Mbps


Atheros has an interesting White Paper about range. It's a bit old
now, but the answer isn't straight-forward.

http://www.atheros.com/pt/atheros_range_whitepaper.pdf

But check out also the commsdesign link above -- it disagrees on
some tests with the atheros one.
--
Whose posting was this .signature Google'd from?
Related resources
April 11, 2004 11:32:40 PM

Archived from groups: alt.internet.wireless (More info?)

Right. 802.11g falls back (eventually) through 12, 9, then 6 Mbps. 802.11b
uses a completely different encoding scheme, and the bitrate sequence 11,
5.5, 2 and 1 Mbps.

Some confusion arises because people hear that the 802.11g standard
includes, and requires support for, the 802.11b standard. This is correct,
but it refers to the fact that an 802.11g AP is required to support
connection of 802.11b clients using 802.11b encoding methods. 802.11g
clients are required to support "safety" measures in the presence of 802.11b
clients, to allow the 802.11b stations to detect transmit attempts by
802.11g stations.

This can lead to the incorrect conclusion that 802.11g is required to
devolve into 802.11b if the signal strength is too low. As far as I can
tell, this behavior is not required, but it might be permitted. For example,
I imagine it's okay for a client driver to give up trying to associate under
the 802.11g regime, and retry under 802.11b. Something like that would
probably be a configuration choice, and the criteria for when to do this
would not be addressed by the standards.

"Walter Roberson" <roberson@ibd.nrc-cnrc.gc.ca> wrote in message
news:c5c424$7nl$1@canopus.cc.umanitoba.ca...
> In article <glci70p9s2tqe5ba6c65vor92gkeepr2j6@4ax.com>,
> Phil Thompson <cynical_observer@hotmail.com> wrote:
> :o n Sun, 11 Apr 2004 13:19:47 +0800, "John" <me@mine.com> wrote:
>
> :>Would wireless "b" or "g" be the best option for maximizing distance and
> :>penetration through brick walls?
>
> :they are the same from a radio perspective
>
> They are NOT the same from a radio perspective: they use different
> waveform encodings that have different properties when they encounter
> situations that would lead to multipath.
>
> http://www.commsdesign.com/story/OEG20030114S0008
>
> : and g falls back to b
> :standards at weak signal levels (long distances)
>
> That's not correct. If you look at the symbol rate specs of
> combined 11b / 11g products (such as a Cisco AP1200), you will see
> that they have different symbol rates at long distances. Notice for
example
> in the chart at http://www.54g.org/standards.html that 11g can use
> the symbol rates of 9 and 6 Mbps
>
>
> Atheros has an interesting White Paper about range. It's a bit old
> now, but the answer isn't straight-forward.
>
> http://www.atheros.com/pt/atheros_range_whitepaper.pdf
>
> But check out also the commsdesign link above -- it disagrees on
> some tests with the atheros one.
> --
> Whose posting was this .signature Google'd from?
Anonymous
a b F Wireless
April 12, 2004 12:39:48 AM

Archived from groups: alt.internet.wireless (More info?)

802.11b would be your best choice for those conditions.

Bill Crocker

"John" <me@mine.com> wrote in message news:4078d53a$1@quokka.wn.com.au...
> I'm setting up a wireless network in a two story brick house.
> Speed is not a major concern as the network will be used mainly for
sharing
> a dsl internet connection and not file sharing between the 4 computers.
> Would wireless "b" or "g" be the best option for maximizing distance and
> penetration through brick walls?
>
>
Anonymous
a b F Wireless
April 12, 2004 1:44:02 PM

Archived from groups: alt.internet.wireless (More info?)

On 11 Apr 2004 18:50:44 GMT, roberson@ibd.nrc-cnrc.gc.ca (Walter
Roberson) wrote:

>That's not correct. If you look at the symbol rate specs of
>combined 11b / 11g products (such as a Cisco AP1200), you will see
>that they have different symbol rates at long distances.

actually I had looked at the specs of a b/g card and noted that as the
signal strength diminished the speed and encoding was the same.

Looking at the AP1200 I see the sensitivity speed is the same for b
and g at -89 dBm = 5.5 Mbps, -91 dBm = 2 Mbps both b and g using DSSS
so at the limit of range g is the same as b

My comment about the radio side being the same refers to signal power
and frequency, which ultimately detemrine range. Fancy coding may
improve bit rates at a given signal strength, or improve resilience to
multipath or other inerference.

The commsdesign paper compares a and g, didn't gain much on b vs g

>11g can use the symbol rates of 9 and 6 Mbps

then falls back to using 5.5 Mbps and the same rates and encoding as
802.11b


Phil
Anonymous
a b F Wireless
April 12, 2004 1:46:45 PM

Archived from groups: alt.internet.wireless (More info?)

On Sun, 11 Apr 2004 19:32:40 GMT, "gary" <pleasenospam@sbcglobal.net>
wrote:

>Right. 802.11g falls back (eventually) through 12, 9, then 6 Mbps. 802.11b
>uses a completely different encoding scheme, and the bitrate sequence 11,
>5.5, 2 and 1 Mbps.

g includes this latter encoding scheme and drops back to it once the
signal is too weak for 6 Mbps. The spec sheets I have read for 802.11g
devices all quote the same encoding and sensitivity at the ragged edge
as they quote for b, as g uses OFDM then drops back to DSSS

Phil
April 12, 2004 7:52:46 PM

Archived from groups: alt.internet.wireless (More info?)

John <me@mine.com> wrote:

> I'm setting up a wireless network in a two story brick house.

You should consider HomePlug's. No problems with wall/floors/ceilings.
--
Groeten,

Antonio (Voor email, verwijder X)
Anonymous
a b F Wireless
April 12, 2004 7:52:47 PM

Archived from groups: alt.internet.wireless (More info?)

> You should consider HomePlug's. No problems with wall/floors/ceilings.

I've tried various HomePlugs and they did not work well in my home. I gave
them all away. YMMV.

Best,
Christopher
April 13, 2004 12:35:08 AM

Archived from groups: alt.internet.wireless (More info?)

In article <J6WdnRGNTLZZXefdRVn2iQ@giganews.com>, "Christopher Glaeser" <nospam@nospam.com> wrote:
>> You should consider HomePlug's. No problems with wall/floors/ceilings.
>
>I've tried various HomePlugs and they did not work well in my home. I gave
>them all away. YMMV.


Really?? You had better results in a Brick (not stick) built home with
wireless?

>
>Best,
>Christopher
>
>
April 13, 2004 1:10:55 AM

Archived from groups: alt.internet.wireless (More info?)

The 802.11 standards do not prescribe how the fallback scheme works. Here's
clause 9.6 ("Multirate Support") from the 1999 802.11 standard:

"Some PHYs have multiple data transfer rate capabilities that allow
implementations to perform dynamic rate switching with the objective of
improving performance. The algorithm for performing rate switching is beyond
the scope of this standard, but in order to ensure coexistence and
interoperability on multirate-capable PHYs, this standard defines a set of
rules that shall be followed by all STAs."

The rules merely state that the transmit rate must be among the basic or
mandatory set of rates, and must also be in the set of rates known to be
offered by the receiving station. Other than that, the transmitter is free
to hop around among supported rates however it pleases. In practice, all
vendors implement an orderly fallback scheme, but it may differ somewhat
from vendor to vendor, or be affected by configuration settings. For
example, it is usually possible to configure an AP router to support "g"
only, which usually means it will not connect clients using 802.11b rates or
encodings, the purpose being to avoid hybrid nets which necessarily have
degraded performance.

I may have misled a bit when I referred to 11, 5.5, 2, and 1 as 802.11b
rates. Support for these rates and the associated encoding schemes is
mandatory in 802.11g. The set of required rates is defined in clause 19.1.1
of 802.11g:

"... transmission and reception capability for 1, 2, 5.5, 11, 6, 12, and 24
Mbit/s data rates is mandatory."

Obviously most vendors implement all of the optional OFDM rates up to 54
Mbps. But the support requirement does not dictate which transmit rate must
be used in a given situation.

"Phil Thompson" <cynical_observer@hotmail.com> wrote in message
news:0nlk70d08gks8gdssb66c6lca23olcv833@4ax.com...
> On Sun, 11 Apr 2004 19:32:40 GMT, "gary" <pleasenospam@sbcglobal.net>
> wrote:
>
> >Right. 802.11g falls back (eventually) through 12, 9, then 6 Mbps.
802.11b
> >uses a completely different encoding scheme, and the bitrate sequence 11,
> >5.5, 2 and 1 Mbps.
>
> g includes this latter encoding scheme and drops back to it once the
> signal is too weak for 6 Mbps. The spec sheets I have read for 802.11g
> devices all quote the same encoding and sensitivity at the ragged edge
> as they quote for b, as g uses OFDM then drops back to DSSS
>
> Phil
!