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Coverage Patterns

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Anonymous
a b F Wireless
October 6, 2004 5:03:51 PM

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

Friend of mine is getting cable Internet service, and is thinking
about going with a wireless router. House is a two-story colonial,
frame construction. Is there somewhere I could see the typical
coverage pattern of such routers? That is, something that would help
us decide where in the house the best location for it would be.

John Jones, Detroit

More about : coverage patterns

Anonymous
a b F Wireless
October 8, 2004 7:30:48 AM

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

On Thu, 7 Oct 2004 14:30:04 -0700, "Tom C." <tomc70NO@SPAMcomcast.net>
wrote:

>Typical 2-story house with
>wood framing and this router totally blankets my house with a Wi-Fi signal.

Where do you have it installed?

John Jones, Detroit
Anonymous
a b F Wireless
October 8, 2004 1:10:10 PM

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

I installed the router on a shelf above my desk at the very back wall of our
house. Our house is longer than it is wide, so the backyard is out my
office window and the signal reaches up to the garage and holds more than
50% of the signal with around 75% signal quality. Surfing the web is very
fast - no slowdowns at all.


"John Jones" <jjetroit000@ameritech.net> wrote in message
news:o e2cm0pnbla00hrlh96ggh1g924tace7gv@4ax.com...
> On Thu, 7 Oct 2004 14:30:04 -0700, "Tom C." <tomc70NO@SPAMcomcast.net>
> wrote:
>
> >Typical 2-story house with
> >wood framing and this router totally blankets my house with a Wi-Fi
signal.
>
> Where do you have it installed?
>
> John Jones, Detroit
Related resources
Anonymous
a b F Wireless
October 8, 2004 1:10:52 PM

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

Oh yah - one more thing . . . my office is on the 2nd floor.


"John Jones" <jjetroit000@ameritech.net> wrote in message
news:o e2cm0pnbla00hrlh96ggh1g924tace7gv@4ax.com...
> On Thu, 7 Oct 2004 14:30:04 -0700, "Tom C." <tomc70NO@SPAMcomcast.net>
> wrote:
>
> >Typical 2-story house with
> >wood framing and this router totally blankets my house with a Wi-Fi
signal.
>
> Where do you have it installed?
>
> John Jones, Detroit
Anonymous
a b F Wireless
October 8, 2004 1:27:08 PM

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

On Thu, 7 Oct 2004 14:30:04 -0700, "Tom C." <tomc70NO@SPAMcomcast.net>
wrote:

>Sorry Jeff, but I have to disagree with you. Three walls are not
>"impossible". I just got a Netgear WGT624 Wireless 108mps Router and I'm
>going through floor framing and SIX walls total. Typical 2-story house with
>wood framing and this router totally blankets my house with a Wi-Fi signal.
>At the farthest reach, the signal reduces to 11mps, which is still very
>good. Directly below my router is my dining room where my wife surfs the
>net with a 54mps connection.
>
>I switched from a 54mps Linksys Wireless Access Point which barely worked at
>the farthest reach. This new Netgear router is great and solved many
>problems.
>
>- Tom C.

Whee... Why don't I have such good luck? I have never made it
through that many walls with a reliable connection. What's your
secret? What client radios are you using? Any open doorways and
hallways? Who's your sorcerer?

Let's play with the numbers and see where they lead.

The WRT624 belches about +13dBm into a +2dBi antenna for a +15dBm
EIRP. At the other end is probably (my guess), an laptop with a built
in antenna. At 11Mbits/sec, it has about -83dBm sensitivity. Antenna
gain is a disgusting -2dBi.

When I did my own testing in 1999, the average wood framed residential
wall was good for -6dB of loss, while the floors were -10dB. Note
that this is only the *ADDED* loss contributed by the walls and
floors, and do not include any path loss over a distance.

My guess is your overall range is about 75ft from one end of the house
to the other.

Free space loss (dB) = 96.6 + 20 log F + 20 log D
Where:
F = Frequency (GHz)
D= Distance (miles)
logs are base 10, 5280 ft/mile
FSL = 96.6 + (20 log 2.4) + (20 log 75/5280)
FSL = 96.6 + 7.6 -40 = 64.2 dB loss.
(Somebody please check my math. I haven't had my morning coffee yet).

So, we start with the TX EIRP of +15dBm, loose 64.2dB over the
distance, and end up with a receive sensitivity of -83dBm. The fade
margin is:
+15dBm - 64.2dB -(-83dBm) = 34dB
That means that we can lose 34dB more signal and still just barely
communicate with the laptop over a distance of 75ft.

With my measurements of about -6dB for walls, and -10dB for floors,
that will give you about 5 walls, or 1 floor and 3 walls which can be
penetrated.

However, please note that the receiver sensitivity reference level is
at a BER (bit error rate) of 10^5, which is fairly lossy and would not
provide reliable communications. You would need at least +10dB more
signal to make it reliable. Therefore, my guess would be 4 walls, or
1 floor and 2 walls maximum.

Drivel: When I was making the loss measurements, we had a very
difficult time making sense of the numbers. A wall should be 6dB per
wall and should be linear for additional walls. Instead, additional
walls contributed less and less loss for each additional wall. After
about 4 walls, the signal level was strictly free space loss and the
additional walls had little effect. Huh? Eventually, we figured out
that as the number of walls increased, the tendency for the signal to
leak AROUND the walls became more pronounced. It was going out
windows, bouncing around stairwells, and generally avoided going
through the walls. This might be what's happening here. Any
possibility that instead of going through 6 walls, your signal is
going around some of them?


--
Jeff Liebermann jeffl@comix.santa-cruz.ca.us
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 AE6KS 831-336-2558
Anonymous
a b F Wireless
October 9, 2004 8:36:35 AM

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

On Thu, 07 Oct 2004 21:33:31 GMT, John Jones
<jjetroit000@ameritech.net> wrote:

>Would a "g" router follow the same general pattern ("g"s are 5.8GHz,
>right)?

You've got the letters mixed up.
802.11 2.4GHz 1 or 2 Mbits/sec
802.11a 5.7GHz OFDM up to 54Mbits/sec
802.11b 2.4GHz 1, 2, 5.5, and 11 Mbits/sec
802.11g 2.4Ghz OFDM up to 54Mbits/sec
(or more with proprietary enhancements).

At 2.4GHz, the antenna patterns would be the same no matter what type
of modulation or data rate. However (insert drum roll), the faster
you go, the "stronger" the signal you need to maintain the data rate.
More accurately, a better S/N (signal to noise) ratio is needed at
higher data rates. The pattern is the same, but you'll need to be
closer to the access point in order to obtain the faster speeds.

5.7Ghz antennas have about twice the gain (+3dB) as at 2.4GHz, for the
same size antenna. However, nothing is free in this world, so the
vertical beamwidth is even narrower at 5.7GHz. Also, free space loss
is about +3dB more at 5.7Ghz. Unfortunately, many dual band antennas,
sound on 802.11a/b/g multimode access points are nothing but a best
compromise between 2.4Ghz and 5.7Ghz operation. The result is usually
a rather ugly looking "cloverleaf" type of pattern, that puts lobes
where you least need them, and almost eliminates the horizontal main
lobe at 5.7GHz.

>He's got a "work" laptop, but I don't know what OS it's running, and
>whether or not he'd have sufficient admin rights to install
>NetStumbler. Good thought, though. And the other problem is: how can
>we test this BEFORE Comcast does the install of the cable modem
>splitter?

Laptops are good. I run into the problem of the "corporate" laptop
all the time. Many users do not have administrator rights to their
own machines. So, I setup a bootable Linux cdrom with all the
necessary tools. See:
http://www.remote-exploit.org/?page=auditor
for a very nice cdrom full of wireless and wired LAN tools. Boot it
and run. If the customer is paranoid, pull the hard disk and leave it
out while testing. Try Kismet instead of Netstumbler:
http://www.kismetwireless.net/documentation.shtml


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831.336.2558 voice http://www.LearnByDestroying.com
# jeffl@comix.santa-cruz.ca.us
# 831.421.6491 digital_pager jeffl@cruzio.com AE6KS
Anonymous
a b F Wireless
October 9, 2004 3:14:00 PM

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

Very nice cdrom of software. Sure seems to be downloading slow via HTTP.
Couldn't get the FTP to connect using WSFTP

--
Bob Alston

bobalston9 AT aol DOT com
"Jeff Liebermann" <jeffl@comix.santa-cruz.ca.us> wrote in message
news:udpem09s0a14hql11vfcpu0hh53elfujpn@4ax.com...
> On Thu, 07 Oct 2004 21:33:31 GMT, John Jones
> <jjetroit000@ameritech.net> wrote:
>
>>Would a "g" router follow the same general pattern ("g"s are 5.8GHz,
>>right)?
>
> You've got the letters mixed up.
> 802.11 2.4GHz 1 or 2 Mbits/sec
> 802.11a 5.7GHz OFDM up to 54Mbits/sec
> 802.11b 2.4GHz 1, 2, 5.5, and 11 Mbits/sec
> 802.11g 2.4Ghz OFDM up to 54Mbits/sec
> (or more with proprietary enhancements).
>
> At 2.4GHz, the antenna patterns would be the same no matter what type
> of modulation or data rate. However (insert drum roll), the faster
> you go, the "stronger" the signal you need to maintain the data rate.
> More accurately, a better S/N (signal to noise) ratio is needed at
> higher data rates. The pattern is the same, but you'll need to be
> closer to the access point in order to obtain the faster speeds.
>
> 5.7Ghz antennas have about twice the gain (+3dB) as at 2.4GHz, for the
> same size antenna. However, nothing is free in this world, so the
> vertical beamwidth is even narrower at 5.7GHz. Also, free space loss
> is about +3dB more at 5.7Ghz. Unfortunately, many dual band antennas,
> sound on 802.11a/b/g multimode access points are nothing but a best
> compromise between 2.4Ghz and 5.7Ghz operation. The result is usually
> a rather ugly looking "cloverleaf" type of pattern, that puts lobes
> where you least need them, and almost eliminates the horizontal main
> lobe at 5.7GHz.
>
>>He's got a "work" laptop, but I don't know what OS it's running, and
>>whether or not he'd have sufficient admin rights to install
>>NetStumbler. Good thought, though. And the other problem is: how can
>>we test this BEFORE Comcast does the install of the cable modem
>>splitter?
>
> Laptops are good. I run into the problem of the "corporate" laptop
> all the time. Many users do not have administrator rights to their
> own machines. So, I setup a bootable Linux cdrom with all the
> necessary tools. See:
> http://www.remote-exploit.org/?page=auditor
> for a very nice cdrom full of wireless and wired LAN tools. Boot it
> and run. If the customer is paranoid, pull the hard disk and leave it
> out while testing. Try Kismet instead of Netstumbler:
> http://www.kismetwireless.net/documentation.shtml
>
>
> --
> # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
> # 831.336.2558 voice http://www.LearnByDestroying.com
> # jeffl@comix.santa-cruz.ca.us
> # 831.421.6491 digital_pager jeffl@cruzio.com AE6KS


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.774 / Virus Database: 521 - Release Date: 10/7/2004
Anonymous
a b F Wireless
October 9, 2004 3:14:01 PM

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

On Sat, 9 Oct 2004 11:14:00 -0500, "Bob Alston"
<bobalston9NOSPAM@aol.com> wrote:

>Very nice cdrom of software. Sure seems to be downloading slow via HTTP.
>Couldn't get the FTP to connect using WSFTP

Did you setup your email address as the password in the config for
anonymous logins? If you left it at the default (some gibberish about
ws_ftp), it will fail on some ftp servers that check for a valid email
address as the ftp password. Also, I suggest you setup ws_ftp to
default to the PASV mode, which seems to work better.

500MBytes is gonna be slow no matter what you use. Also, most servers
throttle (bandwidth limit) on a per connection basis to insure that
some bandwidth is always available.

I just drived into the support pages and found that a new release is
coming real-soon-now.


--
Jeff Liebermann jeffl@comix.santa-cruz.ca.us
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 AE6KS 831-336-2558
Anonymous
a b F Wireless
October 9, 2004 4:20:28 PM

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

OK Got the FTP connection to work.
<banging head against PC monitor>

--
Bob Alston

bobalston9 AT aol DOT com
"Jeff Liebermann" <jeffl@comix.santa-cruz.ca.us> wrote in message
news:1e4gm0d927851pdiu13issn8t8cljvtvrv@4ax.com...
> On Sat, 9 Oct 2004 11:14:00 -0500, "Bob Alston"
> <bobalston9NOSPAM@aol.com> wrote:
>
>>Very nice cdrom of software. Sure seems to be downloading slow via HTTP.
>>Couldn't get the FTP to connect using WSFTP
>
> Did you setup your email address as the password in the config for
> anonymous logins? If you left it at the default (some gibberish about
> ws_ftp), it will fail on some ftp servers that check for a valid email
> address as the ftp password. Also, I suggest you setup ws_ftp to
> default to the PASV mode, which seems to work better.
>
> 500MBytes is gonna be slow no matter what you use. Also, most servers
> throttle (bandwidth limit) on a per connection basis to insure that
> some bandwidth is always available.
>
> I just drived into the support pages and found that a new release is
> coming real-soon-now.
>
>
> --
> Jeff Liebermann jeffl@comix.santa-cruz.ca.us
> 150 Felker St #D http://www.LearnByDestroying.com
> Santa Cruz CA 95060 AE6KS 831-336-2558


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.774 / Virus Database: 521 - Release Date: 10/7/2004
Anonymous
a b F Wireless
October 10, 2004 3:06:01 PM

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

On Sat, 9 Oct 2004 12:20:28 -0500, "Bob Alston"
<bobalston9NOSPAM@aol.com> wrote:

>OK Got the FTP connection to work.
><banging head against PC monitor>

Ummm... I've never solved a datacomm problem by cranial impact. That
also only works with glass CRT's. I wouldn't attempt that with an LCD
monitor as you're likely to bash in the thin glass and void your
warranty. Perhaps wearing a hat might cushion the impact and still
achieve the desired effect.


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