nlos wifi?

snipped-for-privacy@sti.net hath wroth:

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.

Jeff Liebermann wrote in news: snipped-for-privacy@4ax.com:

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 hath wroth:

Sorry, I forgot about Canopy. Start here:

I've had no 900MHz Canopy experience.

Well, the comic book character is still around:

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:

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:

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.

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

Jeff Liebermann wrote in news: snipped-for-privacy@4ax.com:

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.

snipped-for-privacy@sti.net hath wroth:

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:

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

Ron

snipped-for-privacy@sti.net hath wroth:

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:

(more if you wannit).

You might want to read about MIT Roofnet, which is one of the better documented mesh networks.

Be sure to read their observations at:

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:

Is valuepoint any good?

Ron

And actually there was another LOS manufacturer that Motorola just bought up and sorry I can't think of the name now. Sorry.

NLOS is really notorious with WiFi. Obstructions like water bodies (trees) and terrain pretty much kill / deflect whatever signal you output from APs.

If you wanted to boost signal strength though, one of these 0.5 Watt boosters might help.

That will give a solid boost over the standard radios, especially with a good directional antenna or Yagi. Parabolic antenna is also a good choice, again a matter of experimenting:

Directional Sector Antennae:

Parabolic: Yagi: One other idea that may or may not be feasible in your environment would be to build a relay of access points. This might actually work better if you have mountainous terrain (power sources being primary concern).

HTH /