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5 km Range Commercial Wi-Fi Available
prostoalex writes "Japanese company Maspro Denkoh will start selling transmission systems, enabling WiFi signal over 5 km, Network World magazine reports. From the article: "There are two types of antenna: one is a tube-shaped model about 40 centimeters long, and the other is a much shorter and square-shaped model. Combining two of the tubular antenna -- one on each end of the link -- will result in a transmission distance of about 5 kilometers while one of each antenna will work on distances up to 2 kilometers and two of the compact antenna will be fine for up to a kilometer, the company said.""
Trango, Motorola Canopy, just to name a couple of proprietary solutions. Hell, I've even made a 16+ mile link with 802.11b SmartBridge radios. How do you think WISP's can go into and stay in business?
What are "decent speeds?" 50+ Mb/s over 802.11a and 11 Mb/s over 802.11b are easily attainable at 5 km assuming line of sight. 802.11g typically isn't used for long distance links. Using yagi ("tubular"), patch ("square"), or parabolic grid antennas at both ends is standard procedure. Nothing new here.
The company I work for has got a bit more than 3,500 customers using fixed wireless covering a third of a state, and 5 km is nothing. This post, in fact, traveled 4 km to a point-multipoint residential sector, then 31 km point-to-point on another frequency, then 28 km point-to-point, and then fiber from there. We've done this for more than four years and maintain an uptime for commercial customers that usually exceeds four nines (reliable power at the customer location being the primary determinant of 99.99 vs. 99.999 reliability).
How what is described here is unique mystifies me, other than I'd have to guess Slashdot is now doing product placement. In that case (pardon me while I enjoy this tall glass of Coors Light. Remember, for a taste of the Rockies, it's Coors), I'd have to understand their position.
yes, but this poster clearly lives in the US. So if HE got it, He would get in trouble.
The Kruger Dunning explains most post on
As others have pointed out, sending a WiFi signal over distances greater than 500 feet is nothing special. I worked for an ISP in 2001/2002 that was doing wireless Internet service. At the time, Verizon did not give a rat's ass for doing DSL there, and the local cable company couldn't find their ass with GPS unit and a flashlight, so they didn't matter either. The longest distance we did was 15 miles, that was through high voltage electircal transmission lines (125,000 to 250,000 Volt range ones) and over a sizable lake.
5Km. Whoopiee.
Im sorry if I cannot fail to see why parent is modded interesting.
;)
There're lots of uses for long-range WiFi in municipal areas which lack DSL and other broadband alternatives. Where WiFi ISP's can start offering cheaper access to their customers when they dont need to put hotspots as close anymore.
I'm currently working at such ISP, where we are currently using uplinks to local hotspots over ~20km on the 2,4 and 5ghz spectrum. Achieving a high bandwidth over these long ranges has always been a problem with reasonably priced antennas and techniques. Though, I've yet to test out these new antennas and see if they are better than the antennas we are already using, free sight vs non-free sight between nodes etc.
1-2km or more to our hotspots from a customer isnt uncommon, it's relatively easy to guarantee 10mbit access aswell.
Provided there are no trees in the path
No, no it wouldn't.
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These are directional antennas, and directionality is achieved by focusing.
If you used something like this for indoor coverage, you would have one small corridor of great signal, and more dead spots than you started with.
If you want great indoor coverage use this stuff: http://www.andrew.com/products/trans_line/radiax/
--e
It would also broadcast your network 4.9 miles more than you need...
How do you expect an antenna that has a 5km range to exceed 4.9 miles? That's half again farther than it what it's range is.
Repeat after me:
KILOMETERS ARE NOT MILES!!
KILOMETERS ARE NOT MILES!!
KILOMETERS ARE NOT MILES!!
Unregulated != Unlicensed
The FCC regulates all radio communications within the United States. Just because the frequencies that WiFi utilizes don't require a license (within a certain power level), doesn't mean you have free reign of the spectrum.
BTW, this is perfect for amateur radio operators looking to extend their WiFi networks. Hey, we're licensed!
Of course. Here we go:
Windows is like decaf - it tastes like the real thing, but it won't get you through the day.
Such speed-of-light latency would exist, as you say; and would be irrelevant due to other factors, as you say. What you seem to be missing is that that latency is present for _any_ kind of link. In fact, the speed of light in fibre (just to take as an example one of the more likely convential signalling media) is slightly less than the speed of light in a vacuum you used in your calculation. Ain't no way bits'll get from point A to point B faster'n light.
This is just a random press release from a company selling boring old wireless kit. There isn't anything special about getting 5km of range with off the shelf wireless gear,
If anyone cares the math is not that hard to follow:
You take the transmitter output power, subtract any loss in the cable between the transmitter and the antenna, add the gain of the anteana. http://db.osoal.org.nz/eirp-calculator.html
Then you have to subtract the free space loss of your path ( the loss you get by putting the signal across the air ): http://db.osoal.org.nz/freespace-loss-calculator.h tml
And finally you add the recieve gain of the receiving antenna, subtract the loss from the cable on the recieving end and compare with the receive sensitivity of your wireless receiver. I have bundled the rest of the calculation into this bit of javascript.
For example, if I have two 2.4ghz radios that output 15dbm (32mw) that have a recieve sensitivity of -83db that are in waterproof boxes on the antenna mounting connected to two 22db antenna's 5km apart very roughly.
15db - 1db + 22db = 36db or ~3981mw (just under the 4 watt max).
- 121.65db for our free space loss
+ 22db - 1db = -64.65
-64.65 is the strength of the signal received at the other end, fortunately the receiver has a receive sensitivity of -83 so we are in business. There is a link margin of ~19db to account for a little bit of noise, fade, solar flares, alien abductions etc.
If you want more range, increase the power of the transmitter or the gain of your antenna. The government limits ( 4 watts for 2.4ghz, 250mw for 5.3ghz and 4 watts for 5.8Ghz in New Zealand ) are going to determine your maximum range barring some magical new wireless gear that has a better receive sensitivity.
I am a lawyer and this constitutes legal advice and I shall indemnify you against any losses arising from taking it.
Yes, you are the only one. (well actually no, but we won't talk about "them")
These wireless things are very low power, in the U.S. 2.4 is limited to 1W (30dBm) transmit power. If we give these guys _way_ more credit than they deserve, and say their antenna is 20dBi (would be illegal by FCC standards, unless you cut the TX power to ~600mW; but what the hey, lets exagerate), which gives you 50dBm EIRP (100W). Due to the 3-dimensional nature of RF propagation, the power falls of as the inverse square of the distance. So, by the time you are 5ft away, the energy density will have fallen enough to put the effective power back down around 30dBm. By 50ft, you are down below 0dBm (1mW), and by the time the beam has expanded enough to intersect people (would vary, depending on how high up / isolated the antenna is, say 500ft), it should be down to about -30dBm (1uW).
Since 2.4ghz (and all other radiation below ultraviolet) is non-ionizing, the only harm would come from heat. One micro-watt is not a lot of heat. For comparison, a 1Kw microwave oven (which operates at a similar frequency), emits at 60dBm, into an enclosed, reflective chamber; which does not significantly degrade the signal strength. And yet it takes 30seconds to warm up a burrito, with a signal 1,000,000 times stronger than what you would be exposed to.
You are getting far more energy flux just from the local TV stations, many, many miles away from the transmitter. Not to mention all the cell towers, paging systems, SCADA, telemetry systems, HDTV, AM/FM radio, ground based radar systems, police radar guns, carrier links, HAMs, 2-ways, and even cosmic background radiation. There is already a good bit of energy passing through you, and the amount added by WiFi, regardless of antennas, is minimal
Now get a really expnsive, huge antenna, say 30dBi, and dump a watt into it. Then focus it on your eyes for a few hours, and you may experience some discomfort.
This is not to say that RF systems are all harmless, don't go climbing FM radio towers while they are live, RF burns hurt, I know.
I use a homemade corner reflector. I put my AP in the front left corner of my house and aim the reflector towards the right back corner and I get full coverage everywhere I need to. Yeah there's some dead spots, but it wouldn't be practical for me to be using a computer in that area anyway. I made mine out of cardboard and the aluminium stuff that roofers use. You can get a roll for a few bucks.