Non Line of Sight Broadband 168
gfilion writes "IEEE Spectrum has an
article about nifty wireless adapters that don't require LOS. At first, NLOS wireless may not sound like a big deal. After all, ordinary radios and cellphones are non-line-of-sight devices. But they don't carry broadband data. What makes the latest generation of NLOS wireless technology worth talking about and having is that it delivers data at high rates over substantial distances."
ordinary radios ...are non line of sight (Score:2, Informative)
Re:ordinary radios ...are non line of sight (Score:2, Informative)
Re:ordinary radios ...are non line of sight (Score:2)
Re:ordinary radios ...are non line of sight (Score:1)
Re:ordinary radios ...are non line of sight (Score:1)
Re:ordinary radios ...are non line of sight (Score:2)
Cinder block is a poor conductor. Unless there's a lot, radio goes right through.
Re:ordinary radios ...are non line of sight (Score:2)
I'm curious why you made that comment. Don't worry, I'm not assuming you're a dumb ass, I'm assuming you know more about it than I do and was hoping you could explain a little more clearly what you meant.
Re:ordinary radios ...are non line of sight (Score:2, Informative)
I hope that this clears up some confusion.
Re:ordinary radios ...are non line of sight (Score:2)
Yes it does, thank you.
Re:ordinary radios ...are non line of sight (Score:2, Insightful)
First, FM is a modulation mechanism; many frequencies only propagate through the ionosphere under rare conditions. This includes the VHF (30MHz-300MHz) used by FM radio and much of TV.
However, VHF is substantially propagated by diffraction and refractive modes. I receive a VHF TV station regularly which is on the other side of a mountain from me.
High bandwidth technologies often require line of sight because other propagation modes create "multipath"-- there are multiple paths that provide nearly equivalent signal strengths. This smears bits together. The bandwidth of what you're expressing limits multipath from being such a concern for FM radio-- to express an audio signal that is mostly under 10KHz, as long as the paths don't differ by more than
Re:ordinary radios ...are non line of sight (Score:1)
Re:ordinary radios ...are non line of sight (Score:2)
So are you saying that the radio wave enters the tunnel and then bounces around? If so, that explanation is better than the 'radio passes through concrete' explanation I got a couple of posts ago.
Re:ordinary radios ...are non line of sight (Score:2)
So are you saying that the radio wave enters the tunnel and then bounces around? If so, that explanation is better than the 'radio passes through concrete' explanation I got a couple of posts ago.
Different frequencies are blocked or impeded by different substances, depending on stuff like wavelength. For instance, microwaves are heavily attenuated by water, so a rainstorm can degrade the transmission
Re:ordinary radios ...are non line of sight (Score:1)
EM will pass through concrete at these frequencies but most tunnels are built to go under something, and that something usually reflects or absorbs a large portion of the wave.
Re:ordinary radios ...are non line of sight (Score:1)
Um... what's YOUR definition of Line of Sight? Because it doesn't appear to be the same as everyone else's definition. (Unless of course, you can "see" radio waves with your eyes!)
If you read the entire article, you would have read:
"LOS systems rely on a high-power transmitter at the base station, an unimpeded line of sight between transmitter and customer, and a highly directional outdoor antenna at the customer premises,
How would you explain people being able to listen to a radio in their house/apartment/dorm-room? (And don't go telling me that "the radio signal goes in through a window and bounces around your house until it finds your radio antenna", because it just isn't true.)
Re:ordinary radios ...are non line of sight (Score:5, Informative)
FM is Frequency Modulation. it is a mode of transmitting. what you are talinkg about FM or the 88-108Megahertz broadcast band, is not line of sight. that low of a frequency has both ground waves and sky-waves. this is how in west michigan I can recieve WLUP Chicago on 97.9MHZ easily by swinging a directional gain antenna in that direction. Also, Frequencies from 88MHZ up past 450MHZ also can take advantage of tropospheric ducting.
Line of sight doesn't start until past 1.2 GHZ 802.11 equipment at 2.4ghz act like line of sight outside because of water vapro and water bearing items (leaves, squirrels, children) suck up large amounts of signal..
so NO FM is not line of sight. not in the correct term nor in your definition.
Re:ordinary radios ...are non line of sight (Score:2)
Also vhf/uhf ducting is a pretty rare occurance - I only seem to hear it happening a few times a year - like when you get the chance to talk on a repeater thats way up in Canada (done that) when you normally can't.
Re:ordinary radios ...are non line of sight (Score:2)
Re:ordinary radios ...are non line of sight (Score:1)
Fine by me - if it weren't for the fact I'm extra class already
Re:ordinary radios ...are non line of sight (Score:2)
I do not that 2 meters is primarily LOS, which is just slighly higher than broadcast at 150 MHz.
Another thing I am not sure of is whether or not the mode comes into play or not.
Re:ordinary radios ...are non line of sight (Score:1)
For example, KGO radio, a 150,000W AM station in San Francisco, CA, has an array that is designed to propagate the radio waves up and down the west coast, and not into the mountains to the east or to the ocean to the west. Reception in northern Canada of the KGO signal is not uncommon.
Amateur radio operators often use high-gain antennas for non-LOS propagation modes, as long as the high-gain antennas for the given frequency are of a reasonable size. (Obviously, a directional antenna on 1MHZ, with a 160M wavelength, would be rather large).
It is true that exceptionally narrow-bandwidth antennas, like parabolic dishes, are generally only used for LOS or reflective propagation modes. However, low-element yagis are routinely used for ionospheric propagation, tropospheric ducting, ground-wave propagation, etc.
Re:ordinary radios ...are non line of sight (Score:2)
Re:ordinary radios ...are non line of sight (Score:2)
We're talking about electromagnetic radiation. Forms include "radio", "tv signals", "light", and "X-rays". It's all one phenomenon.
None of these is "line of sight". (Catch the paradox?
They all bounce off some stuff, get diffracted by different stuff, and pass through still others.
So in our normal world FM radio waves tend to go "line of sight", but pass through several meters of concrete without problems. Mountains are a problem though. (try seeing through a mile of fog: you can see fine for several tens of meters, but a mile becomes a problem). But FM radio also bounces off some atmospheric phenomena.
Somewhere beyond 1GHz, you get less of that bouncing off the atmosphere, and more and more absorption by water (remember the fog example?!).
Roger.
Re:ordinary radios ...are non line of sight (Score:3, Informative)
Modulation schemes have nothing to do with whether a particular transmission is line-of-sight or not. Carrier frequency does. I assume by "FM radio" you mean commercial broadcast FM as in 88-108 MHz. Why then was I receiving 96.5 WFLB (which is in Fayetteville, NC) in Richmond, VA the other morning (which has a 96.5 of its own)? Hint - Tropospheric Ducting (or tropo-ducto, as I call it, since it's nearly indistinguishable from magic - presto-chango and all that).
In general, as frequency increases, so does the line-of-sight nature of the RF. Light, being extremely high frequency RF, is very much line-of-sight. AM Radio, being between 540 kHz and 1600 kHz, can span the globe because of groundwave bending and ionospheric ducting. Amateur radio operators deal with lots of different propagation modes all the time.
Re:ordinary radios ...are non line of sight (Score:1)
Re:ordinary radios ...are non line of sight (Score:2, Informative)
FM radio is more line-of-sight than is AM radio. But of course line-of-sightedness is a characteristic that has absolutely nothing to do with the modulation method but everything to do with carrier frequency. The higher the frequency, the more line-of-sight it is. Consider light, which is very line-of-sight.
FM = Frequency Modulation in which information is encoded by varying (modulating) the frequency of the carrier.
AM = Amplitude Modulation in which information is encoded by varying the amplitude of the carrier.
Mod this up (Score:2, Informative)
FM broadcast radio, as well as cell phones, and broadcast television work in the VHF and UHF bands.
Because of the frequency of the carrier wave, these bands propagate using line of sight which means that the signal's means of propagation are not by reflecting off of something such as the ground or sky.
Lower frequencies, such as local AM broadcast use ground wave propagation, because the signal reflects off of the ground.
Short wave radio tends to propagate using sky wave propagation, because the radio signal bounces off of the earth's ionosphere. This is often refered to as "skip" and can cause signals to travel across the globe.
Re:Mod this up (Score:1)
See this for some cursory information on how diffraction works as a propagation mode for VHF and above. It is not uncommon for the TV signals, etc you receive to be on the other side of a mountain. And reflective propagation modes are -heavily- used to obtain cellular coverage in urban areas.
http://www.crc.ca/en/html/crc/tech_transfer/101
Now if.. (Score:1, Offtopic)
Re:Now if.. (Score:2, Interesting)
It costs on average about $1000-$5000 per home passed by cable. So you can start out building your network small. Or you can spend several hundred thousand dollars to over a million to build a TV station and reach a whole city.
Michael
--
The opinions expressed above are those off one side of my brain, the other side and my employer may not agree.
rural areas (Score:2, Interesting)
Hopefully something useful is done with this and some committee in congress doesn't deem it a threat to 'homeland security'.
Re:rural areas (Score:1)
Re:rural areas (Score:1)
Not that I'd need to, as most communities in my province have broadband, but still.
Re:rural areas (Score:1)
getting my life back (Score:5, Funny)
Re:getting my life back (Score:2)
Finally I can take down my tent under that tower and move in with girl I really love.
When you brought the personal impact of this new technology into focus for us, my first reaction was one of happiness for you. But then I started wondering how you would break it to the one in the tent? I hope you have planned something less blunt than, "Sorry, you're not the girl I really love." We need to be cognizant of the human costs of new technologies. You should at least leave the tent up, I think.
Noone wants broadband? (Score:5, Interesting)
That's really strange. Doesn't AOL cost $30/mo already? What this apparently says is that even though users can have 24x7 net access at a higher speed that doesn't tie up their phone line for a lower cost, they'll stick with what they have.
Who paid for the study, Disney?
Re:Noone wants broadband? (Score:1)
AOL did.
Re:Noone wants broadband? (Score:3, Insightful)
Saving $5 a month but having to learn a new interface, change email, or any other impediment, will stop a large number of users who read maybe 2 sites a week and read email on a non-daily basis. Broadband as a business model is shaky to say the least. Those consumers who want it happen to be those that are least wanted as consumers by the ISPs. Their cuddly minimal use people will be tying up modem pools for decades to come.
Of Course Not... (Score:2, Funny)
I love the "No Broadband Killer App" Argument (Score:2)
Outside of playing interactive games, which is hardly a universal activity, no broadband "killer app" has yet emerged.
I don't know about you, but isn't quickly pirating movies and music a KILLER app? If I had broadband connection like my brother, I would probably have a collection of 200 some movies too.
So what's the real reason? You have a killer app, and a low price in some areas, yet only a fraction of people are subscribing to it? Something is fishy...
Re:I love the "No Broadband Killer App" Argument (Score:1)
Most people want email and web access. I bet a lot of that is for occasional porn, too... statistics somewhere probably suggest that.
I think that for some low usage types, broadband adds nothing to the experience. If they have to wait 2 or 20 minutes for that one mp3 they download a week, what does it matter? They're probably online for a 30-40 minute session anyway.
HDTV hasn't had a big pickup either. A killer app won't be just more speed, but something completely new available. Most people who want good movies are perfectly happy to subscribe to cable or rent, rather than the hassle (and it is a hassle) of downloading movies "for free (not)" from the 'net.
The true broadband usefulness I see for corporate WAN and teleworking. Can't see it being useful to the home user who doesn't do much with the 'net in his/her home. Just those who are already pushing their modem to its limits and staying online forever. Chat users with no local call fees wouldn't get broadband anyway, unless they are big DCC users.
Re:Noone wants broadband? (Score:3, Informative)
Am I the only one that's tired of radiation? (Score:5, Interesting)
I know nothing about this field... but I am curious.
Re:Am I the only one that's tired of radiation? (Score:5, Funny)
Re:Am I the only one that's tired of radiation? (Score:2, Interesting)
It's all very low power (less than 1 watt) and you should be fine, just make sure you keep the antenna pointed away from your head. Now, if it was a big 100watt transmitter you would have something to worry about. If you're really, really nervous the FCC recommends you only broadcast for 6 minutes at a time.
You're much more likely to get killed trying to make cellphone calls whilst driving.
Re:Am I the only one that's tired of radiation? (Score:2)
What happens to human flesh when the power increases? A CB radio puts out 4 watts and it can put the burns much deeper into the skin when contacted. That may be an example of a lower frequency, but higher frequencies such as microwaves, can be accidentally "focused" much like the sun with a magnifying glass. You can catch something on fire across the room (or set ablaze the tires to that black van parked across the street) by attatching a directional 2.4GHz antenna to the waveguide of a microwave oven.
A few hundred milliwatts here, a few hundred there, who's counting? Pretty soon, we won't need jackets in the winter.
Re:Am I the only one that's tired of radiation? (Score:1)
How about that nasty burn you get from a 60 Watt light bulb? Or have you ever watched toast burn in an oven? That's RF baby. Radiated heat is RF.
The cool thing is that thanks to the inverse square rule, the energy levels drop off pretty quick as you move away from the source. That why the light bulb is hot if you put your hand near it, but it's not from a few more inches away.
Perhaps you need to learn the difference between RF heating and ionizing radiation. One is dangerous, the other isn't any more deadly than a hot light bulb.
Re:Am I the only one that's tired of radiation? (Score:2)
You appear to have read too much thoery and not have worked with antennas too much. If the wavelength is small enough, it indeed can be focused.
Re:Am I the only one that's tired of radiation? (Score:1)
Also, I didn't say RF couldn't be focused. ALL RF can be focused, What I said was that 1 Watt wouldn't burn no matter how much it's focused. The statement was in relation to RADIO, not light or ionizing radiation.
I work with antennas all the time, I'm a licensed ham and I operate everything from HF to 10GHz. I know of what I speak.
Re: (Score:2)
Re:Voltages generated by broadcast RF are tiny (Score:1)
Re:Am I the only one that's tired of radiation? (Score:1)
Re:Am I the only one that's tired of radiation? (Score:2)
Re:Am I the only one that's tired of radiation? (Score:1)
I'd worry more about the ones that can't transmit through stuff - if the evil rays went straight through your body that's fine, but if they don't go through that means they're trapped inside you!
Cheers, Paul
Calling people 'mate' since 1991
Skip! (Score:2, Funny)
Re:Skip! (Score:1)
This is good news(great if you're in the sticks)! (Score:3, Interesting)
My house is encircled and enshrouded by a dense cover of mature mapple and walnut trees, such that I'm unable to mooch off my company's wireless internet because there is no line of sight and the trees degrade the connection so badly that it's not even worth trying if there were.
Once this comes down in price(I'm guessing it's still semi-expensive since it's newer technology) it will be great for all the rural areas out here in the sticks.
A friend that owns an ISP in this area already has plans in the works to create a 802.11x grid in the areas surrounding my town in order to provide high-speed access to the farmers and very small towns(less than 50 people) that don't have any form of cable or dsl. So far the only hang-up has been the construction of towers in the void areas where there are no grain bins or elevators tall enough out in the areas where an access point and repeater is needed. Judging by the information provided in this article he may be able to skip out on some of these towers due to the greater distance provided by the NLOS technology.
Re:This is good news(great if you're in the sticks (Score:2)
Re:This is good news(great if you're in the sticks (Score:1)
Yes, I like to call it "Security through shrubery"
You want into my network? NIT!
Re:This is good news(great if you're in the sticks (Score:1)
Re:This is good news(great if you're in the sticks (Score:2)
Only the antenna itself has to be outside the blockage.
Re:This is good news(great if you're in the sticks (Score:1)
Isn't that going to bring 1.1 gigawatts into your house during thunderstorms? Handy for running flux capacitors, perhaps, but not so good for electronics.
Re:This is good news(great if you're in the sticks (Score:1)
You haven't seen my yard or neighborhood. I'm not talking about a few trees here. My yard is more like a forest in the amount and height of mature trees. Most of the trees are well over 50' tall, and those that aren't that tall provide foliage that provides an even better horizontal wall. Add to that the hedge of lilac bushes around the perimeter of the yard, and the large amount of trees in the neighbor's yards and you have not only a large amount of very nice shade and pretty decent privacy, but also a veritable fortress when it comes to getting any form of line of site.
A 30' tall would do little to no good since the trees range in height from 6' tall (lilacs), to 20' (smaller maples), to 50' (largest maples and walnuts). The foliage from all of these trees creates a pretty good area of blockage on both the horizontal and vertical planes.
If I put the antenna up in a high up limb of one of my trees, then the neighbor's trees would do an equally adequate job of blocking the LOS. Also of note is that I don't live in a large city where lots are only marginally larger than the house itself. To reach the edge of my property with antenna cabling to reach an antenna would require a cable that would loose enough dB of signal strength such that the antenna would have to have a pretty high gain on it in order to counteract this. The only other option would be to actually put the access point itself up in the tree, but then I run into the issue of powering the unit, which I suppose is possible via PoE, but generally tends towards being a higher cost of ownership, not to mention digging up my yard to run cable up a tree, which generally defeats the purpose of being 'wireless' in the first place.
Re:This is good news(great if you're in the sticks (Score:2)
As for defeating the purpose of wireless, I think you may have missed the point. The point is getting broadband access, not the fact that you can get it wireless, right? Personally, wireless is only good for my iPaq, and to a lesser extent, my laptop. Put up your own cheap WAP, if that's what you want.
Someone addressed the whole lightning risk thing... again, I'm no expert, but aren't there decent ways to fix this?
Signal loss is a big issue, not sure how I'd handle it. If you're talking cat5, that means you're within 100 meters, which is plenty close to not worry about this. If it is indeed too far for cat5, it's still unlikely to be too far for whatever coax is appropriate for this, is it not?
As for running conduit, you're only talking $1.50 per 10ft... I just checked at Home Depot the other day. It's shitty work, but only ever has to be done once.
Re:This is good news(great if you're in the sticks (Score:1)
As someone else mentioned, in your case the solution is to either get your antenna up higher or make your trees a lot shorter
would work even in urban areas (Score:1)
the article didn't mention the speed, but compared it to Bluetooth. would that be fast enough for video and voice?
Packet Sniffers (Score:1)
Re:Packet Sniffers (Score:1)
...and I just need to encrypt my data.
Have you ever heard of encryption?
Transmitting non-encrypted data over the air is stupid.
Well, but there is a lot of people that do stupid things, out there
Re:Packet Sniffers (Score:1)
TV (Score:3, Insightful)
Re:TV (Score:1)
Yes, but TV is a one-way street (ie - shouting at it doesn't do you any good)
Re:TV (Score:1)
Re:TV (Score:3, Funny)
Re:TV (Score:1)
Whoa there, Trigger. (Score:2)
LOL (Score:1)
Well, that depends on your definiton of broadband. (Score:1)
And it depends on your definition of "substantial" (Score:2)
50 meters? Hmmm...
WTF? (Score:3, Interesting)
Huh? I pay $21.95 for 40Kbps dialup access and $22/month for a second phone line. I'd sure as hell pay $40 a month for HIGH SPEED access. In fact, I'd pay double that without blinking. Right now I'm looking into frame and 802.11 solutions, but I have trouble stomaching $550/month for T-1 speeds, and I've had only minimal luck finding people who are interested in $50/month colo (hey, if you're interested, e-mail me). All I want is high speed, no restrictions on running VPNs, and low latency (so I can use ssh).
And frankly, it seems MARKETING is the real problem. If you offered $20/month dialup users access which was 2.5 times their existing speed for the same cost, they'd be crazy not to take it. So, MARKET it at 128kbps for $20/month, $30/month for 256kbps, $40 for 512kbps, etc. Bandwidth is like a drug - once you realize what you can do with it, you always want more. Maybe people aren't interested in paying $40/month when they spend $20 and use a computer 30 minutes each week, but if you get them in the habit of sitting down whenever they want to look something up, find a recipe, phone number, etc, they will soon *realize* what benefits a permanent, high speed connection have. Heck, think how many trees the phone company would save if everyone used the internet to look up phone numbers, and they stopped printing phone books.
Phone books (Score:1)
I posted this a while ago... (Score:2)
The highlights: non-line of sight, near symmetric T1 speeds to the home user, VOIP, low latency, and adaptive beam-forming. If you're too far for DSL or cable, check us out.
Re:I posted this a while ago... (Score:2)
Already installed at my house (Score:1)
For anyone in the San Francisco Bay Area, take a look at Gatespeed.com. For those of us too far from the CO for DSL, where cable modem service isn't available (if you even wanted it), but still want 256k symmetrical or better, check them out. They had it up and running 4 days after I called them to ask about prices and availability. And it costs about the same as IDSL. They'll also give you static IPs, and don't mind if you actually USE the bandwidth you're paying for.
Re:Already installed at my house (Score:1)
Gatespeed is LOS, which isn't what we're talking about here. Check the article out for the differences. And at $99/mo for 256Kbps, I don't think most folks would consider them a bargain.
NLOS Broadband Already Available (Score:1)
Sprint already in trials (Score:2)
I want MURS (Score:3, Interesting)
Yawn.. (Score:1)
A Plug for WaveRider (Score:2)
Re:Not first post! (Score:1)
Network cards, SCSI cards, etc..., now that'd be a different story.
So take your Linux smackdown out of here.
Re:Not first post! (Score:2)
Dontcha think he meant a 'fast modem' in a PCI configuration? I haven't been able to find the reference you mentioned so I can't read the context.
On a side note: Would a 64-bit PCI slot be better suited for a Video Card than an AGP port? Just curious, I'm not very knowledgable of such things.
Re:Not first post! (Score:1)
LOL!! WTF is your problem!? You must be really riled up if you're going to hide behind an AC just to avoid being modded down.