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| Mesh and Mimo. Fiberoptics = EXPENSIVE. »en.wikipedia.org/wiki/Multiple-i···ications
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»en.wikipedia.org/wiki/Mesh_network | |
patcat88
join:2002-04-05
Jamaica, NY
kudos:1 | Your kidding, you dont realize the more users you jam on 1 wired node the slower everyone's speed will be?
Take your 54 (one node's bandwidth)/4(nodes connected to the first)/5(users on each node)=2.7mbs. Now lets make those numbers real world, 2.7/2(wifi never can do 54mbs)=1.35mbs. Dialup-like DSL anyone? Atleast you usually symetrical rates, so it might be worth it for p2p. Mesh networking is a joke. You cant use wifi to backhaul wifi, and wifi just doesnt deliver the bandwidth, plus it operates in a TINY amount of unlicensed spectrum. Mesh networking really should be called "wifi repeater network", thats what it is, and what happens when you put 1/4 OF AN ENTIRE CITY on a single Linksys? lol | |
| Not working here?
»news.thomasnet.com/fullstory/482806 | |
patcat88
join:2002-04-05
Jamaica, NY
kudos:1 | Read the specifics, I call BS, it uses WIMAX and other spectrum. "Over 100mbs per node" yeah sure, in a perfect lab situation with each user being on the correct antenna, and the node is backhauling to "perfectly" places nodes, "maintaining continous throughput of 35 Mb/s over multiple hops" (quote from site) is what it really is, and that is obviously for one user. | |
Time4aNAPPremium
join:2007-04-09
Des Plaines, IL | reply to patcat88
said by patcat88:You cant use wifi to backhaul wifi Actually I can, and do. All it takes is a standard Wi-Fi radio and a directional antenna pointed at the utility drop sites(s). What's so hard about that?
As a matter of fact, IMHO the best use of mesh technology in many applications is as the backhaul itself. This would certainly include rural areas, where user terminal equipment on the ground would have little ability to contribute to a mesh of nodes that would need to have a line of sight covering many square miles per node.
...and what happens when you put 1/4 OF AN ENTIRE CITY on a single Linksys? You get fired for incompetence. | |
patcat88
join:2002-04-05
Jamaica, NY
kudos:1 | said by Time4aNAP:said by patcat88:You cant use wifi to backhaul wifi Actually I can, and do. All it takes is a standard Wi-Fi radio and a directional antenna pointed at the utility drop sites(s). What's so hard about that? ...and what happens when you put 1/4 OF AN ENTIRE CITY on a single Linksys? You get fired for incompetence. In alot of mesh situations Ive read about not enough wired nodes, and then automatic mesh algorithms send all the traffic through 1 node, and the whole network comes to a crawl.
Also what about other traffic, residential wifi APs, etc? Dont they degrade the speed between nodes? A directional antenna cant be perfect. And also, do the node to node links use one channel (max 40ish mbs), or aggragate channels (there are only 3 BTW), and if they aggragate wont they deprive residential users of speed? What about FCC rules about using the entire 2.4 spectrum per device?
Also then sometimes mistakes are made to use 802.11b as backhaul, and serve a wired mesh node with a SINGLE T1. Watch the traffic jam. | | |
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| 3rd gen?
»wireless-straight-talk.blogspot.···ion.html | |
Time4aNAPPremium
join:2007-04-09
Des Plaines, IL | reply to patcat88
said by patcat88:In alot of mesh situations Ive read about not enough wired nodes, and then automatic mesh algorithms send all the traffic through 1 node, and the whole network comes to a crawl. I think it goes without saying that a mesh algorithm that doesn't mesh is faulty, and needs to be replaced. But one bad algorithm is the exception to the rule.
I'm not sure what you mean by "wired nodes". If you mean conventional copper service drops, that's an expense that wireless mesh is designed to eliminate. Under what conditions would a customer truly need a wired connection?
Also what about other traffic, residential wifi APs, etc? Dont they degrade the speed between nodes? For large installations like this, site surveys are conducted to determine what's in the air. Interference can be limited by designing the system to avoid areas of strong interference, negotiating with current spectrum users for a compromise, etc. A home AP isn't a meaningful radiator, and because it's not part of the big network, it's just ignored even if it can be seen.
A directional antenna cant be perfect. And also, do the node to node links use one channel (max 40ish mbs), or aggragate channels (there are only 3 BTW), and if they aggragate wont they deprive residential users of speed? On the contrary, it's the backhaul that brings the bits to the users. No antenna is perfect, but plenty are good enough. Part of the RF engineer's job is in selecting the right antenna for the job.
I think you might be confusing the three Wi-Fi 802.11 radio standards with channels. Each of the three (a, b and g) have 11-14 actual channels, depending on the country. Furthermore, The CDMA technology used in 802.11b allows simultaneous operation of several hosts on the same channel. Which channels, and how many channels are used for the tower to home links is another engineering task, where a lot of local factors come into play.
On the backhaul it's customary to use a different frequency band that's best suited for that purpose, and to be able to retain all channel and modulation options on the tower to home links. While the tower to home links must be Wi-Fi compatible for use with common retail equipment, the backhaul for large projects can use other types of radios. The 900MHz band is a common choice, since there are reams of data about signal propagation at those frequencies, and more than a few radio and antenna manufacturers. OTOH, using off-the-shelf 802.11a radios (which operate in the 5GHz band) can help keep costs down.
What about FCC rules about using the entire 2.4 spectrum per device? I don't follow you. The 2.4 GHz ISM band has been allotted for operating many different kinds of unlicensed "Part 15" devices. Cordless phones, for example. A portion of the band has been allotted and channelized for 802.11a/b/c operation. Any Wi-Fi installation would have to meet FCC regulations. Using the whole 2.4 ISM band simply isn't an option.
Also then sometimes mistakes are made to use 802.11b as backhaul, and serve a wired mesh node with a SINGLE T1. Watch the traffic jam. First off, 802.11b is not suitable for backhaul purposes because it's still widely used on home equipment, and because it doesn't offer enough throughput to feed 802.11 "last mile" towers. Also, the multiple users per channel advantage of 802.11b isn't needed for tower-to-tower communication. A mesh backhaul needs to be able to serve multiple towers, each of which can be serving upwards of 100 customers.
Again, the whole reason for using wireless is to avoid the great expense and environmental aspect of running wire or fiber. Yes there is mesh technology on the Internet, but that's not applicable here. | |
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