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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.""
This'd be great for home, too, (if it's reasonably priced) because it would guarantee the highest bandwidth is available throughout the house, without any dead-spots, i.e. my wireless won't have to step down to 1mb/s when I'm at the other end of the house.
If this was $5,230 cheaper, and if the FCC wouldn't come after me with a sawed-off shotgun, I'd probably get one of these.
Reality test... am I dreaming?
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?
Pringles can antennas already delivered that back in 2001... Now, if there would only come someone along to pick up these pesky crumbs.
Windows is like decaf - it tastes like the real thing, but it won't get you through the day.
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.
Sure, that world record was a great accomplishment, but what does it do for the general consumer? I don't think anyone's going to want to carry a 10ft dish around with them. Maspro Denkoh's accomplishment is that it can be used practically.
End transmission.
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
Well, putting aside for the moment that the story has nothing to do with new specifications of any kind:
.
.and will they all be integrated into my laptop?
How many different wireless cards will I need to use all the different technologies. .
42.
. .
Yeah, but it's going to sting like a son of a bitch.
KFG
If you measure area of your home in units of KM, then YOU THE MAN!
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Give me LIBERTY, or give me a check.
Correct me if I'm wrong, but wouldn't you start to run into increased latency issues over such a connection? 5km at 300km/ms means that you're talking, um, 0.016ms of travel time each way, per packet. While that does not seem significant, that's assuming perfect conditions (and my ability to do math in my head), and that could build up in the case of multiple transactions. Of course, considering that you're talking a minimum of about 30ms latency to any remote server, I guess it's irrelevant. Ignore me. :-)
My Systems
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.
You are correct that latency is an issue. For 802.11 especially, since each packet is acknowledged individually before the next one is sent (imagine TCP with a fixed window size of 1), you add 1 round trip time to the time to send each packet (at 11mbps, a 1500 byte packet takes about a millisecond and a half, and the acknowledgement takes a few hundred microseconds, so this isn't really a big performance killer).
Another effect, though, is with transmission timeouts. Suppose station A sends a packet, and begins waiting for a reply. Station B sends an ACK. Normally, station A would have priority to send the next packet, since it only has to wait 10 microseconds, versus station B which must wait 50 + 10*R (where R is a random number from 0 to 31). Unfortunately, with a large propogation delay and a small value of R, station B might assume the channel is free and send a packet (a TCP ACK, perhaps) before the second packet from A arrives, resulting in a collision. But that only happens at distances over about 5 miles I believe. Caveat: I haven't tested this effect myself, so I could be wrong in my interpretation of the spec.
Even worse is if the stations are so far apart that a transmission times out before an ACK comes back, but that requires much larger distances (I think it's somewhere around 60 miles, but I could be off by quite a bit on that one).
Repeat after me:
All-caps shouting is evil!
All-caps shouting is evil!
All-caps shouting is evil!
The Tao of math: The numbers you can count are not the real numbers.