nlos wifi?

Does anyone have experience with nlos wifi internet? if so, what was
your success and with what equipment?

Ron

(E-Mail Removed) hath wroth:

>Does anyone have experience with nlos wifi internet?
>
>if so, what was
>your success and with what equipment?

Zero success with NLOS (non line of sight) wireless. The problem is
that it's almost always possible to obtain an initial connection by
carefully positioning the antennas. However, it's almost impossible
to maintain the connection. As things move around, reflections and
path obstructions change, causing the signal levels to go up and down
erratically. To the user, it looks like severe fading in and out. I
have some MRTG graphs (somewhere) of an NLOS link going through a mess
of trees and buildings. You can see the effect of cars going in and
out of the parking lot. When the trees get wet from the temperature
going above the dew point, the signal would take a huge dive. For 2.4
or 5.7GHz, not recommended.

However, all is not lost. There are systems that are made to
penetrate foliage at 900MHz. They're only legal in the US as the
900MHz band is used for cellular in Europe. If this sounds
interesting, kindly describe your requirements and topography.
<http://www.trangobroadband.com/products/m900s.shtml?id=bb>
<http://www.ubnt.com/super_range9.php4>
<http://www.vecimanetworks.com/waverider.html>

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann <(E-Mail Removed)> wrote in
news:(E-Mail Removed):


> <http://www.trangobroadband.com/products/m900s.shtml?id=bb>
> <http://www.ubnt.com/super_range9.php4>
> <http://www.vecimanetworks.com/waverider.html>

Motorola Canopy gear is quite popular, but the AP is fairly expensive.

Was WaveRider bought out ? Didn't realize that.

When I was working for Clearwire, I had problem getting product info from
them. Sure there specs sound decent, but I was unable to get anyone to
claify them for me.

DanS <(E-Mail Removed)> hath wroth:

>Jeff Liebermann <(E-Mail Removed)> wrote in
>news:(E-Mail Removed) :
>
>> <http://www.trangobroadband.com/products/m900s.shtml?id=bb>
>> <http://www.ubnt.com/super_range9.php4>
>> <http://www.vecimanetworks.com/waverider.html>
>
>Motorola Canopy gear is quite popular, but the AP is fairly expensive.

Sorry, I forgot about Canopy. Start here:
<http://motorola.canopywireless.com/products/specshome.php>
I've had no 900MHz Canopy experience.

>Was WaveRider bought out ? Didn't realize that.

Well, the comic book character is still around:
<http://en.wikipedia.org/wiki/Waverider_(comics)>

Yeah. Vcom bought Waverider about 9 months ago and changed the name
to Vecima Networks. They also bought a other companies to expand the
product line. See press releases at:
<http://www.vecimanetworks.com/news.html>

>When I was working for Clearwire, I had problem getting product info from
>them. Sure there specs sound decent, but I was unable to get anyone to
>claify them for me.

Hmmm... Waverider sells through dealers which tend to be better
informed than the marketing types. Engineering is usually
inaccessible.

If you were trying to get proof of NLOS performance, you're not going
to get it from anyone. There's no common ISO or IEEE test procedure,
no standards, and commonly acceptable definition of NLOS. In other
words, converting marketing hype into reproducible numbers is
impossible with NLOS. One measurement is fade margin, which really
worthless in the presence of multipath and other deep fade phenomenon
likely to exceed the fade margin. The best I can do is reliability
(or downtime), which includes all the statistical dropout mechanisms
and gives a good clue as to how many complains are going to be
received from irate customers. See SOM (system operating margin)
chart at:
<http://wireless.wikia.com/wiki/Wi-Fi#Link_Calculations>
However, even this is useless because the fade margin changes as the
highly unstable NLOS environment changes. Most vendors have given up
advertising NLOS or have invented new buzzwords to replace NLOS with
something even less specifically defined. Trango still pushes their
900MHz products as having "NLOS like features". What I find amusing
is that every time there's an advance in the technology, marketing
drags out the NLOS buzzword claiming that the new technology somehow
allows NLOS functionality, while the previous technology obviously
would not. I've seen it happen with the introduction of
OFDM(802.11g), MIMO, WiMax, and various proprietary error correction
schemes.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Thanks to both Jeff and Dan

This is what I am looking for. The place for this application has many
hills much more trees to reach 252 RV sites. However, I am supprised
of the few trees a router can penitrate. I now have a lot of data to
work through.

Thanks again

Ron




On Wed, 25 Apr 2007 09:16:07 -0700, Jeff Liebermann
<(E-Mail Removed)> wrote:

>DanS <(E-Mail Removed)> hath wroth:
>
>>Jeff Liebermann <(E-Mail Removed)> wrote in
>>news:(E-Mail Removed) m:
>>
>>> <http://www.trangobroadband.com/products/m900s.shtml?id=bb>
>>> <http://www.ubnt.com/super_range9.php4>
>>> <http://www.vecimanetworks.com/waverider.html>
>>
>>Motorola Canopy gear is quite popular, but the AP is fairly expensive.
>
>Sorry, I forgot about Canopy. Start here:
><http://motorola.canopywireless.com/products/specshome.php>
>I've had no 900MHz Canopy experience.
>
>>Was WaveRider bought out ? Didn't realize that.
>
>Well, the comic book character is still around:
><http://en.wikipedia.org/wiki/Waverider_(comics)>
>
>Yeah. Vcom bought Waverider about 9 months ago and changed the name
>to Vecima Networks. They also bought a other companies to expand the
>product line. See press releases at:
><http://www.vecimanetworks.com/news.html>
>
>>When I was working for Clearwire, I had problem getting product info from
>>them. Sure there specs sound decent, but I was unable to get anyone to
>>claify them for me.
>
>Hmmm... Waverider sells through dealers which tend to be better
>informed than the marketing types. Engineering is usually
>inaccessible.
>
>If you were trying to get proof of NLOS performance, you're not going
>to get it from anyone. There's no common ISO or IEEE test procedure,
>no standards, and commonly acceptable definition of NLOS. In other
>words, converting marketing hype into reproducible numbers is
>impossible with NLOS. One measurement is fade margin, which really
>worthless in the presence of multipath and other deep fade phenomenon
>likely to exceed the fade margin. The best I can do is reliability
>(or downtime), which includes all the statistical dropout mechanisms
>and gives a good clue as to how many complains are going to be
>received from irate customers. See SOM (system operating margin)
>chart at:
><http://wireless.wikia.com/wiki/Wi-Fi#Link_Calculations>
>However, even this is useless because the fade margin changes as the
>highly unstable NLOS environment changes. Most vendors have given up
>advertising NLOS or have invented new buzzwords to replace NLOS with
>something even less specifically defined. Trango still pushes their
>900MHz products as having "NLOS like features". What I find amusing
>is that every time there's an advance in the technology, marketing
>drags out the NLOS buzzword claiming that the new technology somehow
>allows NLOS functionality, while the previous technology obviously
>would not. I've seen it happen with the introduction of
>OFDM(802.11g), MIMO, WiMax, and various proprietary error correction
>schemes.

Jeff Liebermann <(E-Mail Removed)> wrote in
news:(E-Mail Removed):


>>When I was working for Clearwire, I had problem getting product info
>>from them. Sure there specs sound decent, but I was unable to get
>>anyone to claify them for me.
>
> Hmmm... Waverider sells through dealers which tend to be better
> informed than the marketing types. Engineering is usually
> inaccessible.
>
> If you were trying to get proof of NLOS performance, you're not going
> to get it from anyone.

Not tryng to get NLOS performance results at all. I was just trying to
clarify some of the specs I read in their datasheets.

And.....when I was working for Clearwire, it was the original CW, before
Craig McCaw bought it and started to claim he started CW. I was there in
2001 when the initial $100M investment came in, $30M or $40M went
immediately to acquiring the MMDS licenses.

Unfortunately, the people that took over wanted nothing to do with my
side of the business, engineering, and were only interested in the
Internet service side, so the engineering department was spun-off as
Clearwire Equipment LLC and given several million of the remaining
investment money. The managers of the service side managed to quickly
squander threw the rest of the money frivilously. They purchased a brand
new building in Dallas and promptly furnished it with all Cherry
furniture, and this and that, all in an attempt to do nothing more than
build up the company image, sell it, and get the hell out. Subsequently,
CWeq had to close down because there was no more money coming in from the
(now non-existant) service, and the Gen 2 product development had not
been finished yet to start selling product.

The Gen2 stuff would have been sweet if it was finished. The design was
tri-band (900 mHz, 2.4 & 2.5 Ghz), had a 2ms timeslicing scheme split up
between all of the subscribers. The best feature of it though was that
all of the typical setting's.....modulation type, bandwidth setting,
power levels, and even the freq. band (900, 2.4, 2.5) could be chosen on
a per subscriber basis. One master radio could send to Sub1 in 2.5Ghz in
a fast modulation scheme, and Sub1's uplink could be 900 mhz BPSK. Sub 2
could be 2.5 Ghz both ways, etc.

It was a serious carrier-class design.

If CW wasn't bought by Craig McCaw when it was, they would have been
completely bankrupt in a few more months. The only real asset they had
left were the MMDS licenses.

(E-Mail Removed) hath wroth:

>Thanks to both Jeff and Dan
>
>This is what I am looking for. The place for this application has many
>hills much more trees to reach 252 RV sites. However, I am supprised
>of the few trees a router can penitrate. I now have a lot of data to
>work through.

I just finished a bid for shared internet in a manufactured housing
trailer park. 102 places of which 88 are essentially permanent. Lots
of trees, hedges, and three 2 story buildings in the way. 26ft height
above terrain antenna limit, so no tower is possible. The permanent
sites are rent controlled by the city meaning that any improvements
have to be cleared with the planning department or they might risk
losing their cheap rent. Mostly aluminium siding which RF is never
going to penetrate. In other words, the wireless nightmare from hell.

Fortunately, the land owner also owns all the conduit in the ground.
He was smart when he built the place and has star topology conduit
running all over the park. So, I bid flooded CAT5 or coax cable
wiring in the conduit. It turned out to be cheaper than wireless
because none of the clients would need to buy CPE hardware, antennas,
or pay my exhorbitant installation charges. The remaining open issues
are cost distribution (not my problem), monitoring, repair, abuse
control, and the usual warranty mess.

In short, there are alternatives to wireless, which do not require
drilling through trees with high power RF or high gain antennas. If
you don't have conduit or can't run CAT5, then consider piggy backing
on the CATV coax cable, which every trailer park I've seen has in
place. See:
<http://www.coaxsys.com/products/tvnet_c.php>
<http://www.multilet.com>
<http://www.mocalliance.org>
--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

There is another idea members of the parks suggested and that is
networking routers between park members to cover the park with wifi.

Ron

(E-Mail Removed) hath wroth:

>There is another idea members of the parks suggested and that is
>networking routers between park members to cover the park with wifi.

You're thinking of a "wireless mesh network". This is what the
municipal wireless networks are doing. I think they suck. The
problem with store and forward mesh is that it generates huges amounts
of airtime and traffic for each packet delivered. The maximum thruput
is also cut in half for each additional hop. It can be made to work
better with two radios in each poletop and/or subscriber unit, but I
don't think you'll appreciate the cost. It usually works acceptably
with one or two repeaters, but creates way too much self interference
with more. You might be able to get away with 2 or 3 strategically
located repeaters (poletops), but then you could also install wire
connected access point at those locations and get superior
performance, less interference, cheaper hardware, and fewer hassles.

Why mesh sucks:
<http://www.smallworks.com/archives/00000072.htm>
<http://wifinetnews.com/archives/003972.html>
<http://black.csl.uiuc.edu/~prkumar/ps_files/exp.pdf>
(more if you wannit).

You might want to read about MIT Roofnet, which is one of the better
documented mesh networks.
<http://pdos.csail.mit.edu/roofnet/doku.php>
Be sure to read their observations at:
<http://pdos.csail.mit.edu/roofnet/doku.php?id=interesting>
to get an idea of how it works. Note that the "typical" delivery rate
shows that 50% of the packets just don't get through. 50% packet loss
is considered *NORMAL* for such a mesh network. Retch.

The commercial version of Roofnet is:
<http://meraki.net>

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Is valuepoint any good?

Ron