Distance factor g vs b

All things considered which format will receive further and have
greater sensitivity - a b adapter or a g ?
It has been said on this forum that the newer electronics ( g as
opposed to the b) are better.
Which format travels further and with more sensivity - g or b or is it
better to use a g adapter with b ?

On 21 Sep 2005 21:50:44 -0700, "frankdowling1@yahoo.com"
<frankdowling1@yahoo.com> wrote:

>All things considered which format will receive further and have
>greater sensitivity - a b adapter or a g ?
>It has been said on this forum that the newer electronics ( g as
>opposed to the b) are better.
>Which format travels further and with more sensivity - g or b or is it
>better to use a g adapter with b ?

G goes farther because the receivers are more sensitive.
These are the reciever sensitivities from the DI-624 and are fairly
typical.

54Mbps OFDM, 10% PER, -68dBm)
48Mbps OFDM, 10% PER, -68dBm)
36Mbps OFDM, 10% PER, -75dBm)
24Mbps OFDM, 10% PER, -79dBm)
18Mbps OFDM, 10% PER, -82dBm)
12Mbps OFDM, 10% PER, -84dBm)
11Mbps CCK, 8% PER, -82dBm)
9Mbps OFDM, 10% PER, -87dBm)
6Mbps OFDM, 10% PER, -88dBm)
5.5Mbps CCK, 8% PER, -85dBm)
2Mbps QPSK, 8% PER, -86dBm)
1Mbps BPSK, 8% PER, -89dBm)

PER is packet error rate.

Note that 6Mbits/sec OFDM (802.11g) sensitivity at -88dBm is better
than the equivalent 5.5Mbits/sec CCK (802.11g) at -85dBm sensitivity.

For reference, 3dB is about 1.4 times as far. 6dB equals twice as
far. 12dB is 4 times as far.


--
Jeff Liebermann jeffl@comix.santa-cruz.ca.us
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff,

will a g receiver receive b at a greater distance than a b receiver ?


Jeff Liebermann wrote:
> On 21 Sep 2005 21:50:44 -0700, "frankdowling1@yahoo.com"
> <frankdowling1@yahoo.com> wrote:
>
> >All things considered which format will receive further and have
> >greater sensitivity - a b adapter or a g ?
> >It has been said on this forum that the newer electronics ( g as
> >opposed to the b) are better.
> >Which format travels further and with more sensivity - g or b or is it
> >better to use a g adapter with b ?
>
> G goes farther because the receivers are more sensitive.
> These are the reciever sensitivities from the DI-624 and are fairly
> typical.
>
> 54Mbps OFDM, 10% PER, -68dBm)
> 48Mbps OFDM, 10% PER, -68dBm)
> 36Mbps OFDM, 10% PER, -75dBm)
> 24Mbps OFDM, 10% PER, -79dBm)
> 18Mbps OFDM, 10% PER, -82dBm)
> 12Mbps OFDM, 10% PER, -84dBm)
> 11Mbps CCK, 8% PER, -82dBm)
> 9Mbps OFDM, 10% PER, -87dBm)
> 6Mbps OFDM, 10% PER, -88dBm)
> 5.5Mbps CCK, 8% PER, -85dBm)
> 2Mbps QPSK, 8% PER, -86dBm)
> 1Mbps BPSK, 8% PER, -89dBm)
>
> PER is packet error rate.
>
> Note that 6Mbits/sec OFDM (802.11g) sensitivity at -88dBm is better
> than the equivalent 5.5Mbits/sec CCK (802.11g) at -85dBm sensitivity.
>
> For reference, 3dB is about 1.4 times as far. 6dB equals twice as
> far. 12dB is 4 times as far.
>
>
> --
> Jeff Liebermann jeffl@comix.santa-cruz.ca.us
> 150 Felker St #D http://www.LearnByDestroying.com
> Santa Cruz CA 95060 http://802.11junk.com
> Skype: JeffLiebermann AE6KS 831-336-2558

On 22 Sep 2005 04:51:53 -0700, "frankdowling1@yahoo.com"
<frankdowling1@yahoo.com> wrote:

> will a g receiver receive b at a greater distance than a b receiver ?

[Insert standard rant on not supplying what you're trying to
accomplish and what you have to work with.]

Ouch. That's a tough one. On the bench, the sensitivities for
802.11b CCK modulation are the same for an 802.11b/g and 802.11b only
access points. I theory, they should be identical. In practice, the
802.11g access points use better technology and less noisy chipsets.
I find the 802.11b coverage to be somewhat better with the 802.11g
access points. For example, I had a DLink DI-614+ router in my office
for a while. My own laptops use Orinico classic cards, so it was a
good match. When I switched to a WRT54G 802.11b/g wireless router, I
found that my coverage had increased somewhat throughout the building.
Antennas, locations, and my laptops were about the same. It's kinda
bad anecdotal evidence, but it seems consistant among the
installations I've tested with my laptop.

The big question is how much different? I would guess(tm) about 5-10%
better coverage. That's not much but every bit helps.

If you're trying to do a long point to point link, look into using
802.11g at the slowest OFDM rate of 6Mbits/sec. The sensitvity is
about 3dB better than CCK at 5.5Mbits/sec and will go quite a bit
farther (about 30% farther). I've replaced marginal 802.11b links
with 802.11g links and found substantial improvements in thruput and
reliability.

Also, I should point out that OFDM 802.11g is much better at dealing
with reflections and multipath than CCK 802.11b. That alone will make
a big difference in range and reliability.



--
Jeff Liebermann jeffl@comix.santa-cruz.ca.us
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558