802.11, Horizon Drop-Off And Range 74
tadghin writes: "Rob Flickenger at O'Reilly Network has written a neat little piece about the range of wireless networks and how high antennae need to be to reach the maximum promised range, given factors such as the earth's curvature and the fresnel zone." Not that most people have solid transmitter disks and clear lines of sight to a wireless reciever miles away, but the more the better when it comes to bypassing modems and expensive per-computer hookups.
Earth's curvature? (Score:3)
And then, the scientists came along and pursued their righteous agenda of proving that the world wasn't flat. But we didn't mind, since we were busy milking our cows and scratching an existence out of the ground.
But the same scientists who took away our earth's flatness are now telling us they're running into trouble. They say they can't handle the curvature they invented. Their antennas aren't long enough. They can't even master what they themselves have wrought.
Why couldn't they have left us in peace?
Re:Repeaters and limits (Score:2)
I am a customer, as is my company and 3 co-workers. We run a VPN over the wireless network so we can comfortably work from home. Of course, most of their other customers are brainless Windows lusers with unprotected file sharing, but we sure get great throughput outside the 9-5 moron window.
In case you're wondering, the residential service provides bandwidth-limited internet access, but the bandwidth limiting is done at the ISP. Internal communications over the wireless network run at whatever speed the network is currently capable of. Typical speeds in the evening are in the 2.5 - 3.0 mbit/s range, with latency between stations of about 10 - 15 ms.
These guys run on an all-wireless network, with access points scattered all over the Ogden, Salt Lake City, and Provo area. The access points are connected to each other via 802.11 links also. The network is, of course, sensitive to rain and snow, but is quite reliable. Most of the service outages I've experienced in the past year have been human (operations) rather than weather or technology failures.
How about indoor range? (Score:2)
The reason I ask is that I just switched from HomeRF (Intel Anypoint/Symphony RangeLan) to 802.11b (Apple Airport/Linksys WPC11)
My indoor line-of-site range with the 802.11b gear is only about 30' at 11Mbs. Might be caused by the el-cheapo Linksys card, I'm not sure. I'm going to try a 3Com card just to try to eliminate that possibility.
The HomeRF gear gave me much better signal quality out to about 150' in every direction (including past my yard). I'm curious why my 802.11b results seem to be so terrible. I've tried turning off every RF source in my house and still see crappy signal quality.
For now, I've got two access points set up and I'm roaming between them but I'd still like to figure this out.
Re:Well.. (Score:1)
Re:Corporate Bandwidth Providers (Score:1)
Re:Corporate Bandwidth Providers (Score:1)
Nevermind (was Re:Corporate Bandwidth Providers) (Score:1)
(1) For frequency hopping systems operating in the 2400-2483.5 MHz or 5725-5850 MHz band and for all direct sequence systems: 1 watt.
Re:Corporate Bandwidth Providers (Score:1)
Re:No insight. (Score:1)
Re:Assuming terrain is all flat. (Score:1)
Re:Assuming terrain is all flat. (Score:1)
Re:Assuming terrain is all flat. (Score:5)
Hills and things do improve the situation with the equipment that we use with our 2.4 network. The perfect situation is one where you have some sort of blockage just a little before the end of your range. This helps to prevent your transmitters from interfering with their counterparts in case they're transmitting just a bit farther than they should be able to. The best idea would be a cellular style delivery. No reason to go 25 miles with a link. Why not saturate a town or city with transmitters? Build the system (as we are beginning to build ours) where the customer only has to have a small, inexpensive 11db (or lower) flat-panel antenna on their house, without an expensive amplifier or huge LMR-1200 cable.
Wireless is in its infancy, and it's probably going to give us all cancer, but I like being able to take the telco out of the loop (no pun intended).
Re:Bluetooth vs. 802.11b (Score:2)
They both operate in the same frequency range.
This is where you lose me. 802.11b is not upcoming, it is here and there are products on the market for it. It is an extension to 802.11 to increase the data rate, change the encoding and some other things. Many times when people are talking about 802.11 they are referring to 802.11b. There is an upcoming 802.11a that will be a significant change but that is a ways off yet.
Chris Cothrun
Curator of Chaos
Re:Corporate Bandwidth Providers (Score:1)
Re:No insight. (Score:2)
This is hillarious. The story is about the FCC clamping down on a wireless Internet provider using 2.4 GHz devices in an apartment complex for interfering with amateur radio television.
While the Hams are clearly in the right legally, morally I cannot equate 2 guys doing ATV (probably a static image of their callsigns) with an entire apartment complex's high-speed Internet connectivity. If they really wanted to send video, why don't they get the 2.4 GHz Internet service and use Netmeeting???
-ex N3HAU
Re:On the same note (Score:2)
Re:On the same note (Score:2)
Re:Non-News (Score:1)
Re:Non-News (Score:1)
Without amplifiers, there is no "free-lunch." If you're going to increase gain, you're going to reduce coverage somewhere. In the case of omni-directional antennas, when you increase gain in the antenna, you're narrowing the coverage angle. With a Uni-Directional, you're directing all the energy and energy capture to a very small (15 degree X 8 degree for 24dBi) area.
There are ways to configure diversity antennas so that one supports transmit only, one for receive. Then you can put amps on each. You do have to make sure you are not exceeding the FCC gain limits. Usually if you're using amps, you have to do a point-to-point application. Any one interested in wireless network design should check out some of the documents on Breezecom's site. They give a good tutorial on how to increase range and still stay within the FCC requirements....
Non-News (Score:4)
We've been using long-range 802.11d for about a year. We have demonstrated good connections (5.5Mb) between a 5dBi omni-directional and a 24dBi Unidirectional across 17 miles. However our main tower is 165ft in the air, and has a feed line of 10ft to limit cable losses.
We see a number of installations where the users have put up an antenna, run 200ft of feed line, and wonder why they can't get a connection. A good rule of thumb is 7dB/100ft. For each 3dB your signal losses double, so a person with a 200ft feed line has a signal level 1/16th of the antenna level. You would need 14dB of antenna gain just to recover from your feed line losses.
Basically, if you're trying to run wireless, don't expect miracles. If you play by the posted rules things will work, but if not, don't blame the equipment...
Re:Height (Score:1)
When I first started here, one of our clients was an ag business that advertised on DTN and another sat-delivered weather info station. The guy in charge of the account had a station installed in his office and said getting the dish onto the roof was a major hassle.
He said that the entire roof space was actually leased out by the building to a third party whose business was renting roof space for communications. They actually did the installation and placement of the dish, and of course collect a healthy fee for the square footage.
I think it mostly depends on the building, ours is 38 stories with excellent southbound LOS. I notice that some buildings that are ~20 and surrounded by much taller buildings have one or two DirectTV dishes but nothing else, just acres of tar...
Re:No insight. (Score:1)
Oh, man...this couldn't happen to a better person.
I went to middle school with Jeff Wellemeyer (the article mis-spelled his name I believe), and he is *SUCH* a twit. He was a twit in middle school, and in past dealings with my company he has been a twit, and even criminal.
Of course, it probably doesn't help that Darwin is in Chapter 11 right now.
Jeff
Assuming terrain is all flat. (Score:4)
But hills and mountains migth as well *improve* the situation as getting in the way, for the simple reason that all smart access-providers will put their transmitters on one of those high spots.
With a 25 mile range, all you need to do if there's moutains around is put the transmitter at the top of a high one, and everyone who can see that peak, and is closer than 25 miles will get access. Doesn't sound half bad to me.
I'm a lot more skeptical to if the 25 mile range actually is realistical, even taking into account weather and such and not just some laboratory-theoretical limit.
Well.. (Score:2)
Though to get 25 miles, you'll need precicion installation... good cable, solid connections.. 2.4Ghz is very succeptible to small errors in cabling.
Also.. having a high point is good.. but you'll need to cover several channels in order to service many people from that distance...
I get a kick out of wireless articles on /. (Score:2)
This article is rather useless. First of all, Cisco's coverage range (supposedly) goes beyond LOS (that's Line Of Sight). This is due to VOFDM modulation that is using multipath signals in a non-LOS environment. Yes, this may be total marketing hype, but the author of the article doesn't have a clue about this and totally misses the point, assuming that LOS is the only issue.
Slashdot should really give up any attempts at covering wireless technologies. The editors don't know what is valuable information, and the resulting discussions are rather useless as well.
Re:802.11 over long distances (Score:1)
They have nice stuff but it doesn't appear to be all standard 802.11b, which is what I was talking about.
Of course, the round trip delay effects are of little consequence if your MAC has been designed to take that into account. 802.11b has not.
In fact, standard 802.11b will fail completely at 50-60 miles distance, because every transmission will result in an ACK timeout.
Vendors of long-distance bridge links will either use a different MAC, or modify 802.11b in a non-standard way to increase things like ACK timeout.
802.11 over long distances (Score:4)
If you're going to use 802.11 for outside links, you have to take the propagation delay into account. For every mile between the two stations, there is a >10 usecs round trip delay. The 802.11 standard uses a 20 usec time as a slot length. These slots are the basis for the random backoff procedure, and can also be found in the difference between the various inter frame spaces. When the total round trip delay (air+rx+tx delays) becomes greater than 20 usecs, you'll get (some) performance degradation.
The degradation in DCF mode is graceful, but the PCF will basically break down completely in the face of long delays. Fortunately, most vendors don't even support PCF.
Things get worse if you have more than a simple point-to-point link.
In short, 802.11 can work over long links, but don't bet the farm on it, and results may vary with equipment.
Re:Height (Score:2)
This doesn't suprise me. Most buildings aren't short of roof space, and removing them would take effort & dollars. However, if a building did get short on roof space, I guarantee that an audit of what's up there would take place, and anything that a tenant wouldn't justify & probably pay for, would be removed.
Re:Corporate Bandwidth Providers (Score:3)
FCC regs and explanation:
http://www.lns.com/papers/FCCPart15_and_the_ISM_2
Height (Score:3)
You'd be surprised at how little owners know about their rooftops. We had several defunct satellite dishes up there for years, just taking up space. No one knew nor cared. On most buildings, a person could stick an antennae/satellite dish and no one would be the wiser. If enough sys admins that run the networks for large buildings got together, it would be relatively easy to pull this off in even small cities.
Thoughts (Score:3)
As a side note, it's gotten me on some interesting rooftops. The most memorable was a mental institution in southern VA. They didn't keep me, so I guess it turned out okay...
-Omar
How do you prequalify a wireless installation? (Score:2)
Wireless LAN fetish? (Score:2)
I understand that it's cheaper for the networking people if they don't lay cable. However, I can't adequately allow for the management of our desktop computers on a shared 11Mb/s network, even if only 10 people use each wireless node.
I can understand the benefits for mobile users, but we've only a small number of those, and we can accommodate them with wireless if necessary.
Has anyone else come across similar issues? I'd put a wireless network in my home, but not at work... is this issue being addressed by forthcoming protocols?
Re:Bluetooth vs. 802.11b (Score:1)
Re:Well.. (Score:1)
We've got a 17mi link, 9mi of which is water, at "11Mbps" (11Mbps is actually 6.4Mbps).
--
Stupid (Score:1)
Perhaps this gentleman should stick to wired networks, maybe recalculating the maximum lenght of cat5.
a good antenna can help a lot (Score:3)
[Disclaimer: I don't work for HyperLinkTech.]
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Earth's Curvature (Score:3)
Rob's calculations are a little flawed. The horizon for RF signals is not the same horizon for a laser beam.
McGraw Hill's "Electronics Engineers' Handbook" gives and effective earth radius factor "k" as 4/3 for frequencies greater than 30 MHz. This would extend the distance of Rob's calculations significantly.
When doing path calculations, there are a number of other factors that affect reception such as conductiviity, permittitivity, roughness and curvature. Reflected signals which also change the receptive strength are dependant on polarization, grazing angle and ground constants.
In general, creating RF paths can be considered black magic, based on the FM principle (magic). The 25 mile figure is really a best case scenerio, where only atmospheric attenuation is hampering the signal. Still, with some adequate hieght, RF communications can be established near 25 miles if the system is set up properly (ie minimizing signal loss at every stage as was pointed out earlier).
It should also be noted that the system discussed is only point to point and would have little value in reaching a mobile user. Mobile use is severly limited by the type and directionality of the antenna and the amount of RF power on the mobile computer. My own 801.11b link is good for 150 feet and most of that is due to the 10mW on an omni antenna sticking out of my laptop.
Re:Earth's curvature? (Score:1)
If you would have just kept on milking your cows instead of picking up each new gadget these scientists wrought, you'd be in plenty 'o peace.
Re:Simpler equation (Score:1)
[Boy, do I feel stupid!]
Re:Assuming terrain is all flat. (Score:1)
I'm battling just such a situation here in the Detroit area. I've got a client with two campuses separated by three miles over mostly flat ground with the standard trees and 1-2 story buildings cluttering the ground. One building has a 60' tower on the roof, putting that antenna 80' in the sky, and the other has just a small 20' antenna mast on the other building, creating a point-to-point link using Breezecom's 11 mbps gear. Wintertime rolls around and the guy gets great signal strength and quality. We're anxiously awaiting the end of the month, when the trees here in Michigan will start sprouting leaves again. Last year, his signal strength and quality were seriously degraded during the summer. Add a good rainstorm and the resulting water collecting on those leaves and there were days when his point-to-point was completely fucked.
I've recommended he get a second tower on the roof but since it's suburban Detroit, the power mongers in the city building department won't let him have the permits. Thppt.
Re:Balloons (Score:1)
Grab.
Radio Waves (Score:1)
Atmospheric conditions? (Score:1)
Bluetooth vs. 802.11b (Score:2)
But... Bluetooth and the upcoming IEEE 802.11B [cnet.com] (note the B) are going to go head to head. It doesn't have the cool name or logo, but it does have the backing of both IEEE and Intel [zdnet.co.uk]. You may hate Intel, but they have a lot of weight to throw around.
I must admit that I was really excited about the Bluetooth standard, but I would always choose an IEEE standard over an industry consortium. I'm still ticked off that USB has gained wide acceptance.
Unrelated but worth noting: There is some chance of interference between bluetooth and 802.11 [wireless-nets.com].
Alternative (Score:2)
In some cases, the wireless towers would be 1000 ft tall. But that only gets you to just under 38 miles to the horizon. As noted in the article 10k feet gets you 126 miles. There is a diminishing returns factor here.
second minor nitpick point. The formula in question is very practical but only works for near earth heights. The geometry it uses is in fact based on the shape of the parabola (note the simple square root element). The higher the object, the less accurate it is, but it doesn't get bad until you get to hundreds on miles high above the surface. At which point alot of other factors are getting in the way as well.
Check out the Vinny the Vampire [eplugz.com] comic strip
Re:Alternative (Score:2)
More on the Formula, since I looked into this when I used to work with RF stuff.
Let the radius of the Earth = A
Let the distance from the transmittion point to the horizon = B
Let the height of the tower (ie, the transmission point) = H
Let the Radius of the Earth plus the Height of the tower = C
We can now put this into the classic form of the Pythagorean theorem.
A Squared plus B Squared = C Squared Where we want to solve for B
(Make sure that the Units of measure are uniform throughout.)
We could even get geekier by wanting to get the distance as measured along the surface, using trigometric tools, etc. Drawing it out for illustration purposes is useful, too.
The resulting formula is more combersome that the old rule of thumb given in the O'Reilly article, based on the Parabola, etc. But the formula is Good Enough(tm)
Check out the Vinny the Vampire [eplugz.com] comic strip
extrapolation and other issues. (Score:2)
It's also a benchmark. Does this mean it can ever be reached? Looking from the comments of the obviously intelligent slashdot community, I don't think so. But benchmarks are just that. Theoretical performance indicators. All it means is that 802.11b has nifty error control protocols and other stuff that allows you to keep communications integrity at 25miles in a very hypothetical situation. Isn't that what Ph.Ds are supposed to do? As in generate some number from some obscure formula somewhere using obviously hypothetical situations.
However, to look on the bright side: It would be interesting if every 200foot high structure had a dish mounted as relay points in, say, a metro or even suburban area. You are no longer limited to 25miles, regardless of topology. In fact, 802.11b can replace traditional LOS microwave dishes (the huge telco ones) and lower the cost of transmission across borders. Imagine GTE beaming 802.11b from the US to Canada. FCC and CE violations anyone?
List Price (Score:1)
The 25-mile antenna (most expensive) has a list price of $1,069.00. The others are cheaper, going as low as around $100.
Reference: ScanOnline [scanonline.com] (the Bridge Antennas link, in particular)
ObDisclaimer: I'm only referencing ScanOnline because they came up "lucky" in Google.
K45
Re:Earth's curvature? (Score:1)
You're absolutely right. Further confirmation of the Curved Earth Conspiracy comes with the news [mercurycenter.com] that C.K. Johnson, President of the International Flat Earth Society has died. Even though he was 76, I think it was the CIA. He was getting too close to the truth ...
Re:Non-News (Score:1)
Re:Balloons (Score:1)
Re:Balloons (Score:1)
Re:Balloons (Score:1)
Say yes to high rise buildings (Score:1)
Re:Bluetooth vs. 802.11b (Score:1)
Usb isnt good for scanners, or anything that is high bandwidth (thats why you would be streching it with a nic) but its perfect for mice and keyboards, it allows you to use hardware in a more effeciant manner. I would rather have a usb keyboard then a just plain serial one. Same with my optical logitec mouse.
Fight censors!
Re:Finding antennas (Score:1)
http://www.ydi.com [ydi.com]
http://www.netnimble.com/products/index.html [netnimble.com]
http://www.superpass.com/ [superpass.com]
HTH! :-)
Re:Finding antennas - oops... (Score:1)
http://www.netnimble.com/products/index.html [netnimble.com]
Re:802.11 over long distances (Score:1)
Re:I do this -- you should too (Score:1)
"Maybe if the technology could be improved to be a fraction of that of land lines, we wouldn't need ISPs in the first place and connections would be maintained by users themselves for their own personal benefit, but also contribute to the overall system - ala distributed aggregate like Napster. Completely free, diffuse, and powerful. Wireless is the natural medium because it doesn't require any land licensing or other utility fees."
Ummm...if you wouldn't need ISP's how would you be able to share your connection via a wireless infrastructure in the first place? Curious...
Re:802.11 over long distances (Score:1)
Re:Assuming terrain is all flat. (Score:1)
Yeah, it's only been 100 years since Marconi transmitted his famous trans-atlantic England to Canada. Microwave frequencies have been used for about 40-50 years for communications, and digital wireless is about 20-25 years old.
Unlicensed 2.4GHz is not designed for long distance, in fact it is designed not to be long distance. This is to reduce the work of people like the FCC Enforcement, NAB (broadcast radio) engineers and other licensed 2.4GHz radio spectrum users from tracking down interfereing transmitters. Remember, radio waves do not respect politic or property boundaries, so successful (i.e. effective and reliable) use requires coordination and co-operation.
Unless you put the antenna (or other EMF radiators) next to your head, it is not likely you will get cancer from Wireless ethernet.
Re:Non-News (Score:1)
To clarify, there are two cables, at the transmitter and at the receiver. With many RF grade cables, there is significate signal lost in the cable above 1GHz. So if your transmitter loses most of the signal in the cable (mixes with noise), amplifing at the antenna would result in louder noise. Amplification at the transmitter itself is only limited sucess, because increased amplication also amplifies the noise already present at the transmitter though it does overcome signal lose in the cable.
We are talking licenseless (Part 15 in the US) 2.4GHz 802.11(b) here. You cannot amplify the transmitted signal very much, and I believe there is a limit to how high a gain antenna you can use (14db perhaps?), the specs are lower in Europe (7db gain for antennas I believe).
The receivering antenna then has to send that microvoltage RF signal through the cable to the receiver.
Using low-lose cable is a good thing for maximum performance, and using a clear unobstructive path (2.4 is partly absorbed by buildings) is the single best thing you can do to gain distance.
Re:Assuming terrain is all flat. (Score:1)
Sorry, I live in a country where the large daily newspapers print garbage articles about "kids who use cell phones will get cancer".
I also have seen people have actual problems with neighbours because of their amateur radio antennas or external wireless ethernet and fears of cancer.
No insight. (Score:4)
If anyone (i.e. not an electical engineer) wants to learn about radio frequency (RF) propogation, I suggest finding some amateur radio publications such as The ARRL Handbook (2001 edition) [arrl.org]. It provides plain english explaination and particial experience about the operating in the microwave bands.
Typical 802.11(b) usage is under license-free operation for local "ad-hoc" networks. The equipment is designed to operate locally such as a college campus or a company building, not across town. This relates to the license-free usage exemptions (Part 15 or 11, I believe).
If you want higher power or higher gain antennas, you will need a license from the FCC (in USA) or similiar government agency in your country. Interference with other users of the radio spectrum can result in a fine from the FCC. Story about a wireless ISP being investigated by the FCC [arrl.org].
Re:Say yes to high rise buildings (Score:1)
A lot of them don't even know how to turn their computers on. So what's to think that our elected officials will take this into consideration, and they will more likely take the cons into sight, as few as they are.
I do this -- you should too (Score:1)
I purchased it to provide extended converge of my 802.11 network through as much of the surrounding city. Currently, I do not have an amplifier but I am planning to get one.
I have the antenna on top of my Condo, which is about four stories high at the roof. When I first got the antenna and hooked it up I was disappointed with the performance. This, however, is due to the highly collimated beam (8 degrees). The problem was you could get a very good connection for miles away, but you had to have relative line of sight. That is, you had to be facing the direction of the antenna, and vice versa.
This provided limited, unidirectional coverage. I ended up fixing the problem by attaching a rotating stage to the Antenna and having it do 360 degree constant rotations and a few degree pan/tilts. This is controlled by the network, which looks for a signal. Once one is found, the antenna is adjusted to get the best reception and left in that position. This was all done with a simple C program, a bit of math, and a DAC card to control the motor.
This has increased the range significantly and given the simulation of a cell with a radius of equal reception. I was even able to maintain a good connection while driving and changing directions in a car; The system "tracking" the signal as it changes.
Some limitations include the fact it can only track one user at a time, although multiple users could be given equal amounts of connectivity "bust" time by spinning the antenna continuously, similar to the way a streaming server "bursts" data to a local streaming cache which then relays it to the slower client. This might be difficult (on the network), as a connection would be in a constant state of variation going on and off, but is still interesting.
What would really be interesting is if home users connected their wireless networks to one another, forming another totally separate network, analogous to ham radio IP, except a lot faster. Maybe if the technology could be improved to be a fraction of that of land lines, we wouldn't need ISPs in the first place and connections would be maintained by users themselves for their own personal benefit, but also contribute to the overall system - ala distributed aggregate like Napster. Completely free, diffuse, and powerful. Wireless is the natural medium because it doesn't require any land licensing or other utility fees.
One can only dream ~
Re:I do this -- you should too (Score:1)
Simpler equation (Score:2)
The assumtion above permits us to make the approximation
sin(t) = tan(t) = t (+ parts per thousand)
cos(t) = 1 - t^2 (+ parts per ten thousand)
The angle subtended at the earth's surface by two locations r apart is r/R where R is the earth's radius.
Therefore the ratio of the the radius of the earth to the radius plus the tower required is cos(r/R):1.
We approximate this to (1-(r/R)^2):1
However, the radius R is the known quantity, we want to know the height of the tower (which we'd get from the right hand side of the ratio).
The ratio becomes R:R/(1-(r/R)^2)
Now 1/(1-x) for small x is 1+x, and we've agreed that (r/R)^2 is small. Therefore the ratio becomes
R:R*(1+(r/R)^2)
So, the contribution of the tower to the RHS is
R*(r/R)^2 = r^2 / R
So h= r^2 / R
Or hR = r^2
The assumtion here is that h, R and r are measured in the same units. As some deal with values in 'human sized units' (the height), and the rest are far larger (particularly the planetary radius), you can either start throwing conversion factors in, or use metric values where the conversion factors are no more than powers of 10. I'll chose the latter.
I'll assume the mean earth's radius is 6370km. Adjust to taste as you move towards the poles, or vary angles at the equator.
h*6.37e6 = r^2 (h, r both in meters.)
So one way round gives
h = r^2 * 1.57e-7 if r is meters
= r'^2 * 0.157 if r' is in km
(h here is in meters)
The other way round
r = sqrt(h * 6.37e6) gives r in meters
r'= sqrt(h * 6.37) gives r' in kilometers
The guy's equation had already combined foot to mile conversions with the earth's radius in miles, and then applied the square root. That's why the 1.224 (or whatever) may have appeared a bit mysterious. However, the h~r formulations are more transparent as they show the physical constant in the equation rather than some mysterious magic number.
For those worried about the approximations, you don't need to really, because the parts in a thousand and parts in ten thousand were for a 637km range. At a 63.7km range, where r/R is 0.01 the part in a thousand term becomes a part in a million! (and hundred million for the 10000 one).
Enjoy.
THL.
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Which doesn't matter much... (Score:1)
What we need is a 768 Terabit wireless thingy in every city center. But that will probably never happen since even cell phone radiation seems to be enough to fry your brain, according to some people. Imagine what a wireless link that fast will do to your brainstem.
Guacamole dip, anyone?
Re:Which doesn't matter much... (Score:1)
That can't be too healthy either :-)
Corporate Bandwidth Providers (Score:5)
Although most corporate Wavelan users are considerate enough to not use encryption or passwords to protect their networks, a few paranoid companies have begun to implement these revolting practices.
Don't they understand that networks want to be free?
Repeaters and limits (Score:1)
Why can't we use the same idea (multiple antennaes used as repeaters ) for the wireless lan / wan idea?
the only reason not to that I could imagine is the signal strength. But cellphone's signals are relatively weak... I don't see why they're isn't any sort of talk of this.
Re:Which doesn't matter much... (Score:1)
the only anyone even thought of health risks was the close proximity to the brain that cellphone users place the phones.
When will people stop being afraid of radio transmissions?
in the 50's, television broadcasts were feared
then cellphones, now wireless net
I'm moving to cheap land under power lines as a self case study to shut you all up!