New Phased-Array AP Boosts 802.11b Range

ttul writes "Vivato, a well-funded wireless startup, today came out of stealth mode to announce its "WiFi" switch product, a super high performance 802.11b access point that uses an array of hundreds of antennas to provide wide-area coverage to standard 802.11b clients. See stories at Wired, and The New York Times. Vivato's new AP completely changes the economics of WiFi especially for providers such as FatPort and WayPort, who now have the technology to deliver 11Mbps to your laptop even if you're miles from a location -- it's the Jetson's, folks!"

Comments

Why?

[Anonymous Coward]

um, why is it the jetson's? I'm sure it is obvious to everyone but me.

Re:Why?

[Anonymous Coward]

I want to hold back from saying duh.

Here is a quick grammar lesson without being nasty:
Jetsons is plural (like the family; many of them)
Jetson's is posessive (like it belongs to Jetson)

WA4OSH

Repost ?

[Merkins]

Umm, didn't this already get posted today ??
Timothy, do you not not read Slashdot ?

Re:Repost ?

[Anonymous Coward]

Maybe they should add safety precautions to article posting:

Slow down cowboy! You must wait at least 10 hours before posting a story that's already been posted. If you think this is unfair, send an email to everyonethatreadsslashdot@slashdot.org.

Re:Repost ?

[Anonymous Coward]

It's because the advertisement team didn't tell the editors that they've posted this story before.

Re:Repost ?

[Anonymous Coward]

Dude,

You need some serious medical attention OR possibly a stay in a drug rehab facility (and most probably both).

Re:Repost ?

[Anonymous Coward]

It's still on the same damn page too.. It's bad enough when it's a day or two apart, but at least check if anyone else already ran the same story TODAY for goodness sake...

Re:Repost ?

[Anonymous Coward]

To me its more than timothy not reading slashdot. He consistently posts dups, and he is doing nothing to stop it. One of slashdot's editors is constantly reposting and no one else at slashdot is doing anything to make him stop. Slashdot survives on its readers, but it does nothing to improve their experience anymore. C'mon, we bitched enough to get rid of Jon Katz eventually, what exact steps are necessary to make Timothy do a decent job?

cool

[Anonymous Coward]

i just bought a laptop today! :-)

Re:cool

[Anonymous Coward]

You bought yours too soon!

Soon they will be putting phased arrays in your laptop cover. Then you can sit anywhere and wardrive up to 4.3 miles from your laptop without ever leaving your driveway!!

deja vu

[Anonymous Coward]

http://slashdot.org/article.pl?sid=02/11/04/144321 6&mode=thread&tid=126

wow

[Anonymous Coward]

hey how many channels are there? oh gee great now we have a 20 network cap for every few MILES?!?!

someone has been smoking natalies grits, i think.

Do the editors read there own site?

[DAldredge]

This appears to be a dup of a story that is still on the main page... And to think, they get paid for this.

Vivato

[Anonymous Coward]

I suppose something radically changed since this morning. Folks at Vivato must be amazed, getting two front page stories in a single day.

Already read this today

[cscx]

over n'yah

Phased Array Antennas

[Spooge Demon]

The tech is a phased array antenna, there was a good article about using it with 802.11 (notice there is no b) in the IEEE spectrum [ieee.org] a while ago.

Consider it a sort of software antenna, you have a series of antenna that you can bias towards a particular direction. You then listen for incoming signals and use a processor to calculate environmental multipath (RF signals bouncing off buildings, etc.) and then fire off your signal so that the main signal and multipath reflections arrive at the reciever at the same time. Instant gain.

I'm skeptical on the reported max range but they should get a good amount. If you're sitting in the middle of a parabolic dish and so is your target, sure I expect that kind of increase in range, but in the real world...

Re:Phased Array Antennas

[dtg]

I'm skeptical on the reported max range but they should get a good amount. If you're sitting in the middle of a parabolic dish and so is your target, sure I expect that kind of increase in range, but in the real world...

This doesn't make any sense. The purpose of a phased array is to provide gain in a given direction. Generally, this kind of technique isn't used as a feed for a parabolic dish because it's a whole hell of a lot cheaper to turn the dish than to build a phased array.

As for users, higher gain at the receiver will help even if they're using the same antenna as always.

Re:Phased Array Antennas

[calidoscope]

From what the articles said, I'd reckon that the antenna should be good for about 20 dB gain over a dipole. Figure that with the inverse square law, you'd be getting 10 dB in range (a factor of 10). 4 miles in free space sounds like a reasonable figure IF the laptop on the other end is in a reasonably quiet area.

The big advantage of this system is to be able to generate multiple beams - something that is a bit difficult to do with parabolic reflector antennas.

Re:Phased Array Antennas

[Anonymous Coward]

Doubling distance requires 4 times the power, or 6dB.

But their link budget does not add up.

2.4 Ghz @ 7km = 116.93 dB Path loss
36 dBm = Max Legal ERP according to fcc part 15.247
Minimum receive sensitivity of the worst card at 1 Mbps is -80dBm

This leaves a link fade margin of -0.93dBm, assuming there is nothing in the Fresnel zone.

Headline news?

[cmeans]

What is this, CNN's Headline news?..all the news, the same news, every half hour!

Re:Headline news?

[Anonymous Coward]

What is this, CNN's Headline news?..all the news, the same news, every half hour!

I heard that Taco is moving to Fox and getting tarted up, too: a new hairpiece, a facelift, and breast implants! Slashdot: Nudes for Nerds. Skin that matters.

ummmmm...

[Anonymous Coward]

um-yes-wait-let-me-check-oh-yes-it-is-at-the-botto m-of-the-slashdot-homepage-STILL-dept

Whip my karma!

[simonecaldana]

First post! WOAH! (I should do nightly updates at customers' sites more often)

We're on a roll folks

[disc-chord]

I can't believe how fast this technology just keeps advancing. I am so glad to be alive in this day and age, instead of 200 years in either direction. Just think about it for a second, if you were alive in 1802 you'd be getting some amazing technological advances at a rate of ... well pretty slow. And in 2202 we'd just be used to it all, and completely unphased. (i.e. How excited does turning your light bulb on make you today?)

I can't wait to get my hands on one of these new toys!

Re:We're on a roll folks

[Anonymous Coward]

Do you have a bank in nigeria you need me to transfer money out of?

Re:We're on a roll folks

[gozar]

Actually, the late 1800's was when technology affected human lives (at least in America) the most.Before that time it wasn't unusual to go for years without communication to your family that was only a few hundred miles away. Then the telegraph, steam engine, mass production, the industrial revolution began to really change things.

It is an exciting time now, but don't kid ourselves that this is the golden age of advances. We're still doing the same thing, just slightly faster. Give me a call when we have anti-gravity devices, holodecks, and transporters.

Re:We're on a roll folks

[Anonymous Coward]

While the sentiment is appreciated, in 200 years far cooler shit than a mere high-gain antenna are going to be around -- I hope so for the sake of my future kids, anyway. Realize that when the light bulb was first introduced, ppl were excited because it was possible to get quality, consistent lighting at night! Being able to roam a bit farther with your laptop frankly pales by comparison.

Re:We're on a roll folks

[3-State Bit]

It is an exciting time now, but don't kid ourselves that this is the golden age of advances. We're still doing the same thing, just slightly faster. Give me a call when we have anti-gravity devices, holodecks, and transporters.

There's something ironic in that sentence, but I can't put my finger on what. I'll give you a call when I figure it out.

Re:We're on a roll folks

[hornedone]

It's a common fallacy to assume that we live in unique times. Everyone has lived in unique times, throughout prehistory and beyond.

It's all now with a few memories and some hope for the future. And before we geeks crow about how wonderful our portion of the world is--and it is technologically exciting--remember there is a big world of human suffering out there. Or are we living in the 1939 NYC World Fair's vision of the world. Or is it Metropolis? Then there was WWII. That drove technology too, didn't it?

I love my Zaurus running the Crow ROM.

Re:We're on a roll folks

[MtViewGuy]

However, it was technological developments in the second half of the 19th Century that really changed the world.

Three developments that became widely used at this time--the telegraph, railroads with steam-powered trains, and steam-powered ships--literally changed the face of the developed world almost overnight.

Just the telegraph allowed news and other information to be spread over thousands of miles in from the originating point in a matter of hours. The rapid growth of trains made it possible for people and goods to travel hundreds of miles on land in a matter of a few days; and steam-powered ships made it possible to traverse the world's oceans and wider rivers without worrying (generally) about wind and water currents.

Most of the cities in the midwestern USA could not have developed rapidly without the developments I mentioned.

Re:We're on a roll folks

[isaac]

Actually, the late 1800's was when technology affected human lives (at least in America) the most.

Even discounting the effects of the automobile, airplane, and computer, the 20th century brought us widespread vaccination and antibiotics. I think those are at least as important to most people as the railroad and telegraph were.

-Isaac

Re:We're on a roll folks

[Anonymous Coward]

i'm sure you are contributing to human advancement, you're just not telling us.

Re:We're on a roll folks

[Anonymous Coward]

I can just imagine the curious look on the guy's face that found a heavy blob of iron while looking through the ashes of his fire and then figuring out you can throw it further. Or the look on the next guy's face that figures out that you can beat this heavy rock into a really shiny point just by heating it once more in the fire. We now can communicate these new findings in a few seconds all over the world. Technology is such that one good thing leads to another. Sometimes the improvements are faster on the invention than on the payoff of the original product.

WA4OSH

Is this a good thing?

[JohnA]

What if I don't want this super-array to interfere with my local WLAN? It appears that this technology has the potential to create a "mine is bigger than yours" arms race among WiFi users.

Re:Is this a good thing?

[Anonymous Coward]

go back to russia.

Re:Is this a good thing?

[hedley]

I totally agree! I don't want someone beaming hi-power out-of-spec 2.4Ghz radiation. The point of WLAN is that you get a local area ~100ft around the AP. If these guys are successful it will increase the SN ratio on any channel they are on. When the baseband in your client tries to get the medium it will be filled with crap far away from you away. Thus your local performance will suffer.

No more than 18db-20db output power, these guys better have that output power or we will all have a problem. Kinda like the old adage: The squeaky wheel gets the oil.

Hedley

Re:Is this a good thing?

[Merkins]

Did you read the articles ?

The actual output of this thing is on 30mw. It just increases range by locking on to it's clients and adjusting itself to aim more directly at them. because of this, it will actually cause less general interferance than a standard garden variety AP

Re:Is this a good thing?

[Beryllium Sphere(tm)]

Sometimes the FCC regulates how directional you're allowed to be.

The magic word here is EIRP, Effective Isotropic Radiated Power. It's how bright you look to someone who's in line with your RF beam. Even if your total power is low, and you're avoiding interference with people who aren't in line with your directional beam, high EIRP can cause problems for innocent bystanders anywhere on the line between you and your intended recipient.

EIRP increases with transmitter power and with antenna gain (== directionality).

This is why it's technically illegal to put a better antenna on your cordless phone, and why the phones don't come with easily replaceable antennas.

Now, if these people are really smart, they could set their beamforming code to plant a null on any 802.11 network that's not a customer, in which case they'll avoid interference.

Fred KC7YRN

Re:Is this a good thing?

[mindstrm]

Technically illegal?
As you said, it depends on the EIRP.
It may or may not be illegal.

And eirp regulations for the 2.4Ghz ISM band, especially in the US, are quite reasonable. I don't have the numbers in front of me....

Re:Is this a good thing?

[sigwinch]

Sometimes the FCC regulates how directional you're allowed to be.

They may be getting around this using multipath. (I.e., using reflections from large metal objects to provide more signal. Do a web search for rake receiver.) That way they can use multiple weak beams, keep the peak brightness in any direction to a reasonable level, but deliver more coherent power to the receiver. You can do it in reverse to make more coherent power available during reception. CDMA does this to great effect.

Re:Is this a good thing?

[Anonymous Coward]

Fred's comments are on the money ... its 30 mw to about 24 to 29 dBi steered beams, depending on the version. And it does intentionally put nulls on interferers. Also, since it provides greater signal strength to most users, that means more users are communicating with the AP at 11 Mbps or 5.5 Mbps, rather than 1 or 2 MBps. That means each users data transmission use less air time. That means less interference. It does make sense.

Ed, KF7VY

Wi-Fi all hype no action?

[Anonymous Coward]

What does everyone think of Wi-Fi really? I mean we have a Wi-Fi connection at my school, but why would I really want to use it? What use is it to have a connection "anywhere", when most conference rooms and what have you have a cord connection nearby which is infinitly more secure.

Personally I think This story makes several good points about the so called "Decline of Wi-Fi". Is Wi-Fi quickly becoming Why-Fi? Simply an expensive gadget which in general doesn't aid the modern human at all?

Sidenote: Perhaps this would be a good idea on airplanes...

Re:Wi-Fi all hype no action?

[Zeinfeld]

What use is it to have a connection "anywhere", when most conference rooms and what have you have a cord connection nearby which is infinitly more secure

First off convenience, you don't need to mess with wires. Secondly if you have the system configured right ie using the revised scheme done by the A team after the B team messed, then wireless can be more secure than ethernet. Network access can be restricted to NIC cards that are authorized to access that LAN. The basic technology was originally designed for ethernet but came out for wireless first after their 'difficulties'.

Sidenote: Perhaps this would be a good idea on airplanes...

Actually that is in the works. They are already required to be robust against microwave radiation from onboard kitchens so WiFi is not far out.

However your other comments about WiFi being on its way out suggest to me that either you have never used the technology or you are a troll.

Re:Wi-Fi all hype no action?

[Anonymous Coward]

Not sure about you, but this is really useful at the university I go to. We have wireless all over campus, so I can get on pretty much anywhere to access files I need on the local LAN (such as class assignments, my grades, etc). I can also work on my laptop and email assignments right off it without having to copy the file onto a lab machine with a disk or whatever. And yes, while I could plug in to the wall somewhere, some older buildings don't have convieniently located ethernet jacks in every room (if any at all) so it would be a pain in the ass.

Re:Wi-Fi all hype no action?

[akb]

Cost is a big reason for wanting wifi. It costs a lot to wire a building and an impossible amount if you want to compete with the local cable or telco incumbent by wiring a city.

Convenience is the other factor. The importance of this right now is relatively small, but I'd say in a year or 2, handhelds with wifi will be able to break through the chicken/egg conundrum.

Re:Wi-Fi all hype no action?

[Martin Blank]

Cost is a big reason for wanting wifi.

I'm generally suspicious of wireless (I have a semi-paranoid security perspective), but cost could be a huge consideration for me, as I'm trying to figure out how to get my apartment complex to set up high-speed internet. Between a Cogent 100Mbps connection for $1000 a month and this for a central antenna, the costs to the complex may well be able to drop from close to $100,000 for wiring it into every unit to perhaps $5000-$10,000, maybe less. That's far more reasonably in the eyes of the owners, as they can pay it off more quickly. With a little luck, we might actually even be able to get some pretty high speeds for maybe $20 a month -- and the complex might even make some decent profit with it.

Re:Wi-Fi all hype no action?

[div_2n]

Actually it is quite easy to spoof a MAC which is the ONLY way you can filter by card.

If you want a secure WiFi network, try using a Kerberos server for authentication with VPN only access to the network on the other side.

And remember, WEP stands for worthless equivalency protocol.

Re:Wi-Fi all hype no action?

[YetAnotherDave]

> cord connection ... which is infinitly more secure.

Just because most admins are lazy doesn't make the technology unable to secure...

I'm writing this from a laptop in my living room, over an 802.11b connection whose only route to the network is protected by FreeS/WAN.
And yes, I could get a wired connection here, but why deal with the hassle of a 100' cable?

Re:Wi-Fi all hype no action?

[aweraw]

why not both? that's what we're doing where I work...

Re:Wi-Fi all hype no action?

[div_2n]

If by both you mean why not use Kerberos/VPN AND MAC filtering I would say that MAC filtering adds additional administrative overhead that you don't need because MAC spoofing is not hard at all. In fact, you should expect it. Extracting the MAC from an 802.11b and a packet is not very difficult.

Why bother with that which is not secure?

Re:Wi-Fi all hype no action?

[Zeinfeld]

Actually it is quite easy to spoof a MAC which is the ONLY way you can filter by card.

Which is why the new cards will have RSA keys embedded in them during manufacture with digital certificates to authenticate the MAC address.

Re:Wi-Fi all hype no action?

[znaps]

"expensive"
"doesn't aid humans"
"what use is it to have a connection anywhere"

WHAT PLANET ARE YOU ON?!?!

Re:Wi-Fi all hype no action?

[Eagle5596]

I have to *in general* agree with the statements he made. My lab has a wireless connection but I never really use it. If I am doing work that needs an internet connection, I am at a lab station anyway, if I am in a meeting, I actually see it as being a mistake to have Wi-Fi as a lot of people *seem* to be working but in actuality they are only surfing the web. The only real use for it I can see is so that I can work during my lunch break, and sorry but no thank you!

As far as the home issue is concerned, why should I have a Wi-Fi? I rarely surf the web at home, as I would rather spend quality time with my wife, or friends. I see Wi-Fi as a threat to my personal private time more than privacy, it just encourages one to stay glued to the screen for longer and longer hours, substituting the real world for the virtual one.

I do however see the advantage of having Wi-Fi in something like a Starbucks, so that you can easily grab a connection, but seeing as Wi-Fi cards are still more expensive than a regular NIC, and all the deli's, statbucks, and cafes in the area also have wired connections at the tables, I'll stick to the old fashioned connections for the moment.

I do think Wi-Fi has potential, but at the moment it is a "niche" market for me, and something that causes an increase in unproductivity amongst my collegues at work. So I guess I'm still waiting for the next version before I join the bandwagon.

I can say however that we will NEVER have Wi-Fi in my house! Family comes before slashdot, sorry guys ;)

Re:Wi-Fi all hype no action?

[znaps]

That's just you..of course certain people (i.e. non nerds) will not see a big need for wireless connections. The poster above was generalising about _humans_ and wireless networking in general (not just WiFi), not just one person/technology.

Going by his reasoning, a cordless phone is no more useful than one with a cord.

Re:Wi-Fi all hype no action?

[R.Caley]

What use is it to have a connection "anywhere", when most conference rooms and what have you have a cord connection nearby

When you get out of school you will find that those cables don't lay themselves. They are expensive and sometimes hard work (try working when somoene is trying to drill cable runs through stone walls someday).

Even for a simple home nettwork, I would have gone the wireless route if the technology was mature last year when I was laying a cable the length of my (then-) new flat. The difference between plugging in one wireless hub and putting in a couple of sockets in each room with all the structured wiring and hole drilling would easily pay for the extra cost.

Re:Wi-Fi all hype no action?

[R.Caley]

Just because most admins are lazy doesn't make the technology unable to secure...

OTOH, any technology which requires admins to not be `lazy' needs more work before it is ready for the real world.

Most admins are `lazy' becase they already have enough on their plates.

Re:Wi-Fi all hype no action?

[Eagle5596]

That's just you..of course certain people (i.e. non nerds) will not see a big need for wireless connections. The poster above was generalising about _humans_ and wireless networking in general (not just WiFi), not just one person/technology.

Actually when you generalize about humans, I would argue his comments are more valid, because the majority of humans are not nerds, even the majority of humans in developed countries. Most people don't spend their time on the net in large quantities. I happen to be a computer professional and I spend little time on the net. My wife is a systems programmer, and she never uses the net at home. For us we like to keep our personal life real, as opposed to virtual. Under this circumstance wireless ethernets seem pretty useless on the whole. While I would love to be able to code in front of the TV some nights as opposed to coding in the office, it would also mean I would be more prone to working more often in those situations, something I don't really want to do, as I value my free time.

Going by his reasoning, a cordless phone is no more useful than one with a cord.

I have to really disagree with you there, as I think you are grossly blowing things out of proportion. A cordless phone is useful to almost everyone because it is easy to talk on the phone to a friend while cooking, cleaning, or other household activities, it is a way to get more for your time. I'd like to see you surf the web while cooking or cleaning. Wireless connections only change your geography, they don't let you work in parallel.

Then there is the price issue, looking at prices on the net it looks like the minimum you'd pay for a wireless ethernet card is ~$80, plus $100 per access point. I payed $20 for my NIC card and it looks like the current prices have dropped a few bucks. We got the hubs in our house for ~$15, and I currently can find them for around ~$20 looking briefly on-line. Given that each wireless ethernet card is approximatly the price of 4 NIC cards, and one wireless access point is about equal in price to 5 hubs, there is a substantial difference in price. Not to mention when you get around the $100 purchase mark, you are talking about a lot of savings going with the old fashioned method.

For a corded phone you'd pay $7-$20 for a base unit, a base cordless phone is anywhere from $17-$30. True that means in some cases the corded is 3x cheaper than the cordless, the savings is only ~$15 instead of ~$60.

And if you want to make the arguement for wireless phones, well they have an immense value as an emergency phone, the primary way my wife and I use them. They have saved us so many times when one of our cars has failed.

Maybe when wireless becomes cheaper to the user (the user mind you, not the coorporation wiring the area) they will become more popular, but I doubt the majority will ever see a real *need* for such technology, as all it does is allow you to surf in a different area (the living room rather than the office).

Re:Wi-Fi all hype no action?

[Anonymous Coward]

Why would you really want to use it? Why can't you think for yourself?

Re:Wi-Fi all hype no action?

[znaps]

Valid points (apart from the price - WiFi is already cheap)...but if you think about the big picture, wireless networking is not just about surfing the web in your home on your laptop.

When new devices appear which have WiFi built in, then we'll see the 'need' for them (including you!). Right now it's only for people who like to surf the web in more than one location in their home.

Re:Wi-Fi all hype no action?

[Anonymous Coward]

Have you ever wondered how cogent can back up such an offer and still remain in business?

has your head exploded yet? no? just wait.

Re:Wi-Fi all hype no action?

[YetAnotherDave]

um, nearly all technology requires admins not to
be lazy, that's why sysadmin is such a complex job.

Re:Wi-Fi all hype no action?

[R.Caley]

nearly all technology requires admins not to be lazy, that's why sysadmin is such a complex job.

Er, no. Mature and well designed technology works to a reasonable standard out of the box. Yes, there are things to think about, but you're starting from somewhere sane.

`Wi-Fi' as one might assume from something they had to think of a silly name for, comes out of the box useless, leaving the admin to do everything the designers and manufacturer should have done.

slashdot double posts

[thatswimmer]

not only do we see the same story posted more than once, now more than once a DAY!

Duplicate story?

[Dark Lord Seth]

I'm either having the most badass deja-vu ever or Slashdot is posting duplicate stories again. Get your act together people. Let the editors decide which story to post, not that old d20 back from the AD&D days.

RANDOM OFFENSIVE FRAGMENT TROLL

[Anonymous Coward]

maggots exploding out of my shit-soaked pants

Telco's are obsolete!

[Mac Degger]

Think about it: if 1 in 10 (maybe a lot less) people get one of these babies, and run a reasonable VoIP software on it...all you need is a wifi PDA and you've got "free" telephone services!

Hmmm, I guess you'd also want IP6 running...but wow! what a thought: technology makes another middleman obsolete!

Re:Telco's are obsolete!

[div_2n]

Wifi can't replace the telcos. Not yet anyway. And certainly not as long as the FCC keeps the unlicensed frequencies very small and limited.

There are only 3 non-overlapping channels in the 2.4 ghz band in the US. Same goes for the 5.8 band. Combine the throughput on those and in the best case scenario you have about 180 Mbps. Actual performance would probably be half at about 90.

Now lets assume you are going to build your network so that you can honeycomb those channels. If you do it with scalability in mind, at most you are going to have 65 Mbps throughput. Actual performance would probably be about 35 or 40.

There isn't a very good chance that will get a good VoIP service with that espeically if people are using that for web access too.

I'll beleive it when.....

[Chris_Stankowitz]

it sticks around for more than a year. The old addage of I'll beleive it when I see it has fallen victim to too many technologies that didn't make it. I am cheering for this all the way. Hope it makes it and stays.

Comment removed

[account_deleted]

Comment removed based on user account deletion

Apostrophe Watch

[RangerSpeedBumpp]

"It's the Jetsons". Not Jetson's.

C'mon, guys. You're running a major online news service. I'd let this one slide but I see these your/you're its/it's mistakes at least once per day.

Re:Apostrophe Watch

[Anonymous Coward]

please shutup.

Re:Apostrophe Watch

[ender's_shadow]

shut up

Not disappointed

[Compact Dick]

I saw 'by Timothy' and opened this link to check if it would be another duplicate. I wasn't disappointed.

Don't worry, Tim. We still love ya :-)

what about the not-slow people

[hfastedge]

From the wired article:

"We think it'll work reasonably well at pedestrian speed," said CEO Ken Biba,

This company will surely fail. Its technology isnt taking into account laptop joggers, laptop motorcyclists, laptop unicyclists. And leisure, urban helicopterists and skydivers...

Re:what about the not-slow people

[Anonymous Coward]

Won't somebody please think about the children driving around with their WiFi-enabled iPaq/Zaurus/[insert your favorite WiFi capable device] on a Segway whilst talking on their Bluetooth-enabled cell phone which also pulls down info via GPRS and WiFi :P

Actually, it's a test

[BeBoxer]

They are testing one of these new access point to distribute stories. Slashdot had the antenna's pointed to the east coast when the first story was posted. Now they are aimed at the west coast. While the range of coverage for slashdot is much greater now, folks in the midwest will have to deal with the resulting duplicate packets^H^H^H^H^H^H^H^Hstories

Asymmetry and number of users

[Anonymous Coward]

The use of a phased array antenna for transmission to the client is nice, but I wonder if it requires the client to be modified to run special tracking software that sends back multipath information to the basestation to enable it to tune its beam.

This makes me think that the data-link would probably end up being asymmetric --- high data rate down to the client but not so good coming back. Not only would the upstream rate be partially consumed by the multipath measurements, but also the single antenna on the client would have a harder time beamforming out to the receiver array.

The power constraint is probably on the total output from one array and as such, the number of users that any one of them can support is probably fairly limited. This suggests that things can get quite interesting if we put a bunch of these in close quarters. The optimal solution would be for the AP to collaborate and divide up the users among them not by simple distance (voronoi regions) but by effective distance involving the specific multipath environment! Otherwise interference would be a serious problem.

Re:Asymmetry and number of users

[Merkins]

but I wonder if it requires the client to be modified to run special tracking software that sends back multipath information to the basestation to enable it to tune its beam.

It would seem not. In the Wired article, Paul Boutin says he took his own laptop to make sure they weren't doing anything tricky on the client side. He could go everywhere the demonstation engineer went and get good access.

Re:Asymmetry and number of users

[ka9dgx]

The fairly wide spectrum helps a bit with multipath and fading, so it should do ok in that regard.

Antenna gain works both ways, so bandwidth should be good in both directions. The real fun would be having two of these systems talking to each other.

When are we going to get true 802.11b mesh?
--Mike--

Re:Asymmetry and number of users

[Anonymous Coward]

I have a problem with their 7km claim. I think they forgot about leaving a 15dB link margin.

Here is what the downlink looks like:
2.4 Ghz @ 7km = 116.93 dB Path loss
36 dBm = Max Legal ERP allowed by part 15.247 for point to multipoint applications.
Minimum receive sensitivity of the worst card at 1 Mbps is -80dBm

This leaves a link fade margin of -0.93dBm, assuming there is nothing in the Fresnel zone.

Legally, you can't do more than a mile when you are using a worst-case standard off the shelf WiFi card.

The uplink is even more challenging:
2.4 Ghz @ 7km = 116.93 dB Path loss
15 dBm = the output on the worst cards.
The best receive sensitivity you can get at 1 Mbps is around -92dBm. This means their receive gain would have to be about 25dB. (assuming LOS) This is hard to get out of a 1 meter square panel

WA4OSH

Why......

[jwilcox154]

use a Phased-Array AP to Boost the 802.11b Range, when you can use a Pringles Can as the Wi-Fi Antenna to Boost the Range? ;)

Re:Why......

[Student_Tech]

The pringles can is there, just that it is a virtual one instead of a physcial one. Phased-arrays use a bunch of antennas to simulate a beam-type antenna (pringles can), this site http://home.earthlink.net/~jimlux/radio/antenna/ph ased/phased1.htm was the first one I found with useful information, explains the basics and also has some links to some other sites explaining it.

Silence nay sayers, slashdot rules thee

[Anonymous Coward]

this isn't a repost, this is an update worthy of a new story, given the few details of the last.

helluva lot better than CNN or nyt where they'd just revise the story and you'd never know.

War Driving ....

[bizitch]

Fuck war driving - try war standing around and hopping on to x number of nets!

Re:War Driving ....

[Anonymous Coward]

wow... I simply gotta commend you on that sig. funny, funny shit.

Re:War Driving ....

[Anonymous Coward]

WooHoo! A sound Clip!

Re:War Driving ....

[dago]

that was not a funny post !

with a 18 db antenna on the roof of a building there're something like 50 APs available. And wlan equipment is more expensive on this side of the atlantic.

In other news

[yorgasor]

Slashdot was able to boost its reach of certain articles by a factor of 2. Says slashdot editor, Timothy, "The results are very impressive and the technique was surprisingly simple. All we had to do to double the readership for a particular article was to post it once in the morning, and again at night. If our /. readers are anything like the editors, most of them are too lazy to read more than the top couple of articles. If they happened to miss the morning edition of /. we can rebroadcast a "best of /." again in the evening so our lazy readers don't miss out and all the action here."

Re:In other news

[Wild Bill Hickock]

isn't that what slashback section is for ??? I may be mistaken of course ...

Re:In other news

[Anonymous Coward]

a 3dB gain in readership is reall impressive ;)

WA4OSH

Re:Guide to +5:Funny Posting

[Anonymous Coward]

You must be new here. Posts such as that one don't get modded up, they usually get modded down. Don't you ever read slashdot? :)

Quick Everyone, Before Anyone Notices...

[Cyno01]

C&P the highly modded posts from the first post of this article. Its still there on the front page, just scroll down.

obligatory VOIP thread

[frankmu]

ok, i just needed to say this: think of what this can do for Voice over IP!

interesting discrepancy

[ender's_shadow]

it's odd that nytimes says the main proposed use is in the corporate world, while wired mentions dorms. audience demographics?

9 Hours

[tswinzig]

A new repost record, I do believe...

Re:9 Hours

[cscx]

No, THE repost record was one day when they were one or two stories apart on the front page nonetheless.

Re:9 Hours

[Anonymous Coward]

Yes, a story about new Intel chip, iirc.

Re:9 Hours

[cscx]

How right you are.

Here and here, only a few hours apart.

Re:9 Hours

[BeBoxer]

The record was the slashback we had recently which duplicated the PayPal tip jar theft story at the beginning and end of the article. That was impressive.

Imagine a..

[Anonymous Coward]

beowulf of duplicate slashdot articles.

what? they already do that?

what's next? redundant first posts?

re: post

[Scaebor]

it's the Jetson's, folks!

Until I get my flying car and robot maid it not going to be the Jetsons. Somehow AIBO on a skateboard just doesn't cut it for me.

Its a BAD thing . . .

[mofu]

Miles of omni-directional range in a unlicensed, uncontrolled band of spectrum with only three non-overlapping channels??

No thanks, get your own spectrum from the FCC if your going to pull this . . . .

Re:Its a BAD thing . . .

[Moofie]

Ummm...you musta missed that part about it being a phased array DIRECTIONAL transmission.

Is Timothy a script?

[Anonymous Coward]

Can anyone post a link to download ???

Re:Is Timothy a script?

[aweraw]

funny...

We're Proud to Present...

[Twintop]

Don't have time to sit on a computer in a dark room? Get Pr0n on the Go! Download from the park, from your porch, or even in the car!

Duplicate

[alanjstr]

Already on Slashdot

WiFi Is a WASTE OF TIME

[Sex_On_The_Beach]

beat it..
its just a waste of time and money, and won't be mainstream.

Question....

[hawkbug]

Maybe somebody can answer this for me, but I see a major problem with current wireless technology. I currently have an 802.11b access point in my home. I love it, and it gets great range - in fact, so great it goes clear over onto my neighbors property. I had my laptop outside (probably looked like a dork walking around running a constant ping on my thinkpad), and I was able to walk clear onto their property and get a great signal. At first I was impressed... then I started to think about my neighbor. Wouldn't this be a problem for them if they wanted their *own* access point for their network?? I would think that my access point also interferes with 2.4ghz phones in the area. As an example, I had to sell mine because they quit working the second I got this thing. So, if you could expand the range of 802.11b to *miles* - isn't that really going to screw over Joe Blow who wants his own wireless network that just happens to be within range of a provider mentioned in the story???

Re:Question....

[ealar dlanvuli]

(probably looked like a dork walking around running a constant ping on my thinkpad)

My neighbor got worried enough to poke their heads out and ask me what I was doing when I mapped my network range :0

It was... fun... explaining I was accessing the internet.

Re:Question....

[mindstrm]

No, it's all about power.

Yes, there can be interference.. but it's also about power. As long as one signal is significantly stronger than another, it should prevail...
This is also why there are multiple channels... so you can try to avoid overlap.

You can't extend the range of 802.11b to miles.... not omnidirectional anyway... you can in a certain direction, yes.... but the higher the gain, the narrower the 'beam'.

In the case of your neighbor, chances are his AP will be what his cards will see, and yours is what your cards will see, because the signal of the local ap will be significantly stronger.

Re:Question....

[HeghmoH]

I don't know what kind of access point you have, but mine has eleven different channels you can choose from. And even if they do overlap on the same channel, your total bandwidth would probably be limited to 11Mbps between the two of you, but otherwise there shouldn't be any ill effects.

Re:Question....

[EmagGeek]

There are 11 802.11b channels. Each channel overlaps with its adjacent channels to some degree. However, channels 1, 6, and 11 are completely clear of each other (there's a very good reason they set it up this way). Just get with your neighbor and agree on which channels you're going to use.

The reason there are three clear channels is just in case someone wants to set up a cellular network of 802.11b access points. While you do need 6 channels for the standard hexagonal cellular spectrum re-use plan, a lot can be done with just three.

As for interference with 2.4GHz phones, there's no reason to assume that an access point will comlpetely wipe out a cordless phone. The ISM band runs from 2400 to 2483MHz, inclusive, and neither a cordless phone nor an access point will use anywhere near all of this spectrum.

There _are_ obvious implications if everyone goes out and puts a long-haul access point on their roof. The band WILL get crowded and bad things could happen. We'll just have to see how fubar this gets and just wait for the FCC to either start licensing access points (for a hefty fee, of course) or just start pushing everyone to other spectrum like U-NII (5.3, 5.8GHz). The market is sort of going that way anyway.

Re:Question....

[Sentry21]

You can just set yourself to use a different channel than the access point in question. Voila, no interference. Besides, as mentioned in the article, the reason it's as powerful as it is is because it's directional - it beams the signal to you, not to everywhere, so you could be sitting beside it, but if you're not between it and a client, you probably won't pick anything up.

--Dan

Re:Question....

[12013]

i guess that's why they give you different channels... had the same problem with the phone, if you just change the channel away from the default one (you should do that anyway) it should work again. ...so if you neighbour owns an AP aswell i guess you should talk and coordinate on channels...

Re:Question....

[Anonymous Coward]

There are several channels available for each base station. As long as adjacent base stations are on different channels, all is well. The can either exist as independent cells or as part of a meshed network.

Re:Question....

[Anonymous Coward]

I'm too lazy to make an account right now, so don't hate me. But there are a number of articles on the company (and I think they might mention it on the company website too) answering this question. The tech works by directing the coverage in a beam at a specific user--no broad, cloud of coverage, but a tracking beam instead, so the interference is massivly reduced from conventional wi-fi coverage. I think the Wired article might have mentioned this, but I've been reading all I can on it and I know at least a couple of articles have.

Uh huh

[Anonymous Coward]

it's the Jetson's, folks!

It's a repeat, folks!

Re:Watch out ISPs...

[glenstar]

How can the ISP industry survive when anyone can connect to a WAN over 802.11b? AND FOR FREE?

Um... the Internet connectivity has to come from somewhere.

Not a duplicate...

[Penguinoflight]

This must not be a duplicate from all the people getting modded down... not only are the 4,5, and 6th posters getting redundant, the first guy got a troll mod. Is this really not another story, and are the editors really awake?

Re:Not a duplicate...

[fobbman]

The irony is that these people are being modded Redundant for pointing out that this story is Redundant.

Re:Not a duplicate...

[Rorian]

Well, if you look at the two articles, they both link to the NYT article, so they appear to be about the exact same topic.. both also talk about the same startup company (Vivato)...

Maybe /. people are just getting pissed off at their own mistake and so they're doing nasty modding to make themselves feel good?

Actually...

[Bruce Perens]

I think that 802.11b has a legal limitation on the antenna gain to 6 dB. This is so that devices would not interfere with other, distant networks.

Bruce

Re:Actually...

[Anonymous Coward]

Nope. The legal limit is 36db, 1 Watt EIRP --total.

Re:Actually...

[div_2n]

The FCC limitations for the 2.4 band is 1 watt (30dBm) for Point-to-Multipoint. For point to point you can get away with a lot more.

None of that matters though because obtaining true line of sight past 20 miles without more than a 20 percent impedence on the Fresnal Zone is a battle I don't want to fight.

Re:Actually...

[EmagGeek]

Not that i'm aware of. The only limit that I know of is +36dBm EIRP (4 Watts) for point to multipoint links and +48dBm EIRP (~63 Watts) for point to point links.

A 1 watt amplifier with a 6dBi Antenna get's you your +36dBm, while a 1 watt amp with an 18dBi antenna gets you +48dBm. This is why antennae come in convenient sizes of 6dBi, 12dBi, and 18dBi. Combinations of these gains with +24, +27, and +30dBm amplifiers get you to the limits.

802.11b amplifiers and antennae are NOT, I reapeat, NOT illegal. There are certain hoops that you have to jump through, but there's nothing illegal about building a system with amps and antennae. There are no filing requirements, no licensing requirements, or anything. You just have to use certified equipment. Certified equipment consists of a combination of an Access Point, an Amplifier, and an Antenna, and all interconnecting transmission lines, that have, together as a system, been certified to be compliant with FCC rules for the unlicensed spectrum. Of course, such systems cost several times what you can buy COTS (commercial, off the shelf) stuff for, because having equipment certified is not an easy nor inexpensive task.

You may ask why you can't just stick an antenna on your access point. You can, but you have to be aware that you're only changing the receiving antenna. It is against the law for a consumer product to give the consumer access to change the transmitting antenna. The antenna either has to use a fixed, non-removable proprietary connector (reverse SMA, reverse TNC, or other connector that you can't just buy at radio shack), or have an antenna that cannot be removed at all.

For example, look at the D-link 900AP+. It has a single, removable antenna on the rear. If you open one up, you'll actually see two transmission lines connected to the radio card. One of these goes to the rear jack and the other to an electrically short antenna inside the case. This short antenna is the transmitting antenna, which is compliant with the rules because the consumer cannot readily change it.

Also, because these things use separate transmitting and receiving antennae, you'd have to put TWO antennae on the roof if you wanted a longer haul 802.11 system. It wouldn't be enough to simply boost your transmitter EIRP, you'd have to have bigger ears to hear a little laptop that was far away.

Re:Actually...

[Anonymous Coward]

1 watt is 30dBm
4 watts is 36dBm

The legal limit is 1 Watt (or 30dBm) at the intentional radiator and the max ERP is 4 watts (or 36dBm).

WA4OSH

Re:Actually...

[Anonymous Coward]

Their application is a point to multipoint. So you can't invoke the point to point 3dB antenna gain for 1 dB power output rule.

I don't see how they make it past one mile.

WA4OSH

Why should they?

[Perianwyr Stormcrow]

Hell, even I don't read it anymore. I just go into meta-moderation and reply at random to whatever comments come up.

Caught!

[Anonymous Coward]

Can I get a witness?

Karma Whoring 101

[Anonymous Coward]

A repeat, for the newbies:

Whenever /. posts a repeat story, one quick way of getting extra karma is to go through the original story, and repost the highest scoring posts.

This usually gets by the editors too, as we all know that they never read other /. stories.

HEY BRUCEY!

[Anonymous Coward]

Look it up BEFORE you waste our time kid.

Hm.

[SargeZT]

This dosent change the Dynamics of anything. In 3 Days, 802.12.c Will be released! Or some other god damned standard. Who cares about extensions of a soon too die Standard? It's like using Windows on a Server.

Comment removed

[account_deleted]

Comment removed based on user account deletion

Mod down parent

[HBI]

The link in that message is garbage.

Re:Watch out ISPs...

[afidel]

You are missing the point, the wireless mesh network IS the internet. Of course longhaul links would be a bitch with the need for a repeater every 25-30 miles or so.

"Paid Advertisement Section"

[Anonymous Coward]

This is bound to be modded as a troll, but...

I'm sorry, this pair of ads^H^H^Harticles smacks of the kind of reporting seen in Newsweek as of late (remember the Palladium article and the ultrasonic speaker article?). At this point I'm curious about the objectivity of this site's editorial staff.

Please up-mod parent.

[Anonymous Coward]

Finally, somebody gives a damn about quality around here.

Have you noticed how so many free software people -- the Slashdot staff, for example -- have such contempt for attention to detail? How they think it's a waste of time to put forth a little effort and get things right?

So... this is the mentality we want OSS programmers to have? Is it, really? Let's think about this.

Re:STFU, you illiterate asshole.

[DAldredge]

Thank you for such an intelligent response.

Re:Watch out ISPs...

[mindstrm]

Who cares?
The Internet is a bunch of networks hooked together. Whether those networks are chiefly isp's networks, or community networks it doesn't matter.

Problems with cache?

[Rorian]

Maybe Tim doesn't reload Slashdot from the server all the time, and is reading older, outdated articles, which leads to him posting duplicates?

I've seen /. getting a lot of abuse about duplicate posts, but two on the one page?! Oh well, I guess theres nothing better to read online :(

Comment removed

[account_deleted]

Comment removed based on user account deletion

Re:Thank you for having the brain of a slug.

[DAldredge]

I kan spel vry goud. Thnk U vry mch!

Death to war driving?!

[dunkan44]

With this kind of coverage we can scan networks from the comforts of our own homes.. :)

What about upstream?

[Anonymous Coward]

Pardon my ignorance, but:
Wouldn't upstream traffic from a standard 802.11b card to an Vivato access point be horribly slow because of the low power of the card?

Re:What about upstream?

[flatulus]

Phased array antennas will provide receiver gain equal to transmitter gain if reception and transmission are on the same frequency (which is the case for 802.11). This is known as signal path reciprocity. In fact, the "Wi-Fi switch" probably first discovers the client when the client sends a "probe" or "associate" request, looking for connectivity. Once the "Wi-Fi switch" hears the client, it has the opportunity to determine the best tuning of the antenna, which will provide the highest signal gain when transmitting back to it.

Perhaps I should call you in a couple years

[Zen Programmer]

Anti-gravity, holodecks, and transporters.

dammit timothy (#2)

[BiOFH]

Attention /. editors. I want Timothy's fucking job. I have at least one sure qualification he doesn't: I read Slashdot.

Duplicate posts, misleading (or just plain "made up") headlines... ARGH!

See:
http://apple.slashdot.org/comments.pl?sid= 44091&ci d=4592724

(I'm gonna post one of these every time and keep adding links to previous posts)

warchalking

[vectra14]

HELP! we're running out of chalk!!!!

I don't know whats funnier...

[tgd]

The fact that clearly no one who works at slashdot reads their site, or the fact that 2/3 of the people reading this article don't either.

FWIW, people, the replies on the story from this morning are better than these. ;-)

And now....

[Thai-Pan]

... war driving from the comfort of your living room.

/. Effect

[batboy78]

Apparently they didn't get slashdotted this morning, time for round two. Ding Ding Ding.

Re:Watch out ISPs...

[quantum bit]

You are missing the point, the wireless mesh network IS the internet. Of course longhaul links would be a bitch with the need for a repeater every 25-30 miles or so.

Ugh, I'd hate to see the BGP routing tables on something like that......

Terrorism!

[echophase]

The Slashdot editors are terrorists!

I have it from a good source that all these reposts are done because company X won't give their products, for free, to the editors.
So what they do is repost the story so get them slashdotted, thus raise their bandwidth bill.
They usually seem to get free products after the companies realize it's cheaper to fork over a free product than pay excessive bandwidth bills.

the jetsons?

[athlon02]

Uhh, when it (wireless technologies) reaches a few 100Mbit and is used by the masses, then maybe :)

Re:Watch out ISPs...

[afidel]

So we come out with a better routing protocol and use IPV6 blocks and do geographic routing.

To the moderator who moded the above post.

[DAldredge]

Way to go. You managed to waste a mod point on a posting to a duplicate story. And it was not even your typical dup, it was a dup of a story already on the front page.

Way to use your mod points for a productive purpose.

Beowulf!

[toomz]

Imagine how far apart you can keep your beowulf cluster of laptops!

This is an active phased array...

[Newer Guy]

It works much like the active radar antennas that do not move. Here in Santa Monica we have a large phased array of hundreds of fixed antennas aimed at the horizon that are sequentially pulsed on and off to get the familiar 'rotating' pattern of a single rotating radar dish. This design is much more robust then a rotating array as there are no mechanical rotating parts at all...everything is switched by PIN diodes. Military jets also use a variation of this for secure communications. In the jets' wings are switched inductor antennas that are used in a fast frequency hopping scheme over a 50 mhz range. The transmissions can be anywhere within a 50 mhz frequency segment at any given fraction of a second. If the frequency synthesizer at all locations are moving to the same frequency at exactly the same time, the transmisison will sound completely continuous.
They use PIN diodes to change the taps on an inductor to resonate the antenna over the (wide) frequency range. This way, they can use smaller, lighter, narrower bandwith antennas and rapidly tune them to the exact frequency in use at any given moment.

All in all, a very slick technology and another example of a civilian use of military technology.

Super-Dupe-r!!!!

[Anonymous Coward]

Wow, the first time i've seen a dupe comment for a dupe article. Way to go!!!

Boosting Signal Strength

[nautical9]

I was pointed to a an interesting site that sells (possibly illegal in your area) boosters, bridges, antennae and other miscellanea for 802.11B.

This isn't an endorsement - I have no need in my small place, and haven't tried any of this myself, but it sure would be fun playing around with some of this stuff.

PowerBook

[Krach42]

Can I get Wireless networking across the distance of my house now?

Woo Hoo!

[UrGeek]

The last mile problem is SOLVED!

Re:Woo Hoo!

[Anonymous Coward]

I don't think it solves issues like path loss, interference, multipath, non-line of sight... I don't even believe their claim of 7Km. Show me a link budget.

Multiple steerable beams, for better or worse

[dtmos]

The advantages of a phased array AP are two:

-Multiple simultaneous beams. The maximum number of possible beams is equal to the number of radiating elements in the array. The Pringles can, of course, has only one main lobe (beam).

-Near-instantaneous beam switching from one direction to another or, said another way, the ability to track very quickly, since the beamsteering is done electrically, rather than mechanically, as the Pringles can does.

The big question I've not seen answered is, how do they handle the Wi-Fi beacons? A beacon serves multiple purposes--synchronizing the network nodes and advertising the presence of the network to prospective new network members being two of them. If the beamforming is used to reach long distances, the beam is very narrow; new nodes won't be able to detect the network since it's unlikely they'll be in the beam. Conversely, if a wide beam is used to enable new nodes to join, range to existing LAN members will suffer.

I wonder if it's significant that, in the Wired article, the tests were performed starting close to the AP, then walking away from it. It would be interesting to try the reverse...

Crap!

[sigwinch]

Now I have to upgrade to phased-array chalk for my warchalking efforts!

Re:Crap!

[Anonymous Coward]

I don't know of anyone actually having warchalked anything. I have never seen a real warchalking except for the pink stickers at Starbucks indicating they have Wireless Internet available.

Re:Guide to +5:Funny Posting

[Antos700]

Um, hello? Lets think about why they get all misty eyed over Ms. Portman... hmm, It could possibly have something to do with movies she's been in... Not enough? O.K. How about the words "star" and "wars"?

Is this within FCC regs?

[Mister Mudge]

I'm not sure whiich part of the FCC regulations 802.11b falls under, but it's probably the part that covers other unlicensed transmissions. I wouldn't be at all surprised if these phased-array antennae are not up-to-snuff legally, due to WAY high effective radiated power (ERP). The whole idea of unlicensed transmission is that it is in spectrum and at ERP levels that will not have an affect outside an extremely circumscribed area or cause undue interference ... and this is definitely NOT what the new array's goal is ... quite the opposite, in fact.

Re:Is this within FCC regs?

[tommys5]

The FCC has looked this Vivato product over and given approval, at least tentative. The power outut at the antenna (actually, it's a switch) is less than that of a cell phone. I'm not sure what the total power level is of the input source.

Re:Is this within FCC regs?

[Anonymous Coward]

Part 15.247. It falls under the point to multipoint part of the regs.

There is no way you can get 7 KM legally. They must have forgot to add in the link margin in the link budget. The most you can get is about 1 mile.

2.4 Ghz @ 7km = 116.93 dB Path loss
36 dBm = Max Legal ERP
Minimum receive sensitivity of the worst card at 1 Mbps is -80dBm

This leaves a link fade margin of -0.93dBm, assuming there is nothing in the Fresnel zone.

WA4OSH

Re:Is this within FCC regs?

[Anonymous Coward]

All access points are switches (layer 2 devices). I'm sure it's legal. But let's go over the fundamentals again.

It's an access point with a fancy phased array. The point is that the power input to the array cannot be more than 1 watt since it's a point to multipoint application. The array cannot have more than 6dB of gain at 1 watt input because that's the legal max ERP on that band. For a 7km link, there are losses = almost 117 dBm's worth. There is fading you have to overcome. For this, you lose about 15dB minimum of signal. At 7Km away, you have to have a receiver sensitive enough to receive the signal. Most 802.11b cards have an input sensitivity of -80dbm at only 1 Mbps. It gets worse if you want more data throughput. There is simply not enough signal there with an off the shelf 802.11b card to make it work. It's simple physics (unless they are breaking the law).

Insert Star Trek pun here

[Gabrill]

Scotty, beam me up.
I'm givin' her all she's got, Cap'n! It's never been done before, but maybe if I create a phased array from spare phaser parts . . .
It worked, Cap'n! We now have Warp 13! Where's my Romulan Ale?

EIRP regs

[Andy Dodd]

Given that the base station is only running 30 mW, it's almost impossible for them to be out of FCC spec.

(Come on, they wouldn't bother releasing a product that didn't meet FCC regulations...)

30 mW = approx. 15 dBm
The maximum power you may run into an isotropic antenna under FCC regs is 1 watt. 1 watt = 30 dBm.

This means that they have a MINIMUM of 15 dB of antenna gain headroom. That's a lot.

But it doesn't stop there - The FCC allows (somewhat) higher EIRPs. I don't remember the exact guideline, but it's something on the order of reducting peak transmit power by 1 dB for every 3 dB of antenna gain. (Not sure of the exact numbers, but you do get an increased EIRP ceiling as you narrow the beamwidth.)

So if you put on a 3 dBi antenna, your peak transmit power isn't 27 dBm (For 30 dBm EIRP), but it's 29 dBm (For 32 dBm EIRP).

Do a Google search for N9ZIA, you should reach the site of a guy that has done a LOT of WLAN hacking (not all of it legal, while he is very knowledgeable of regulations, he often chooses to ignore them...) He has some good info on the exact FCC regs in the band.

cost

[rot26]

And how much is this puppy? I didn't see price mentioned anywhere.

Re:Why...... Yagi and helix antennas are better

[Nonillion]

About 6 months ago a friend and I were doing some experements with 6 element yagi antennas and a linksys access point. We were easily able to acheive 1 mile ranges on open flat terrain. But the real kicker was when we were able to get pings (0-25% loss) form a distance of 8 miles. But to do that we had to get about 300 feet of elevation, park the car and carefully turn the beam till we found the signal. Overall the signal strength was around -75dBm, the connection was usuable but just barely..

[ ... miles away ... ]

[Anonymous Coward]

How much is that in meters?

Re:[ ... miles away ... ]

[wa4osh]

4.3 miles is 6.9 Kilometers. (4.3 x 1.6)

Phased Array Mesh?

[macemoneta]

Couldn't this technology be combined with mesh network technology? Instant cellular replacement, just add handsets.

Re:Phased Array Mesh?

[Anonymous Coward]

There is a lot more to a cellular system than a mesh with handsets. How will you interface with the Public Telephone Network? You need a gateway. Who will pay for local and long distance calls? You need an accounting system. Who will make sure people are paying you for their service? You will need a an authentication and authorization service. Whose system will you use when it's not your own? You will need roaming. What will hand over the call from one cell to another? You will need full mobility including handover. How will the police locate you when you call 911? You will need location services. Who will build the hundreds of thousands of cell sites? How will the government monitor your phone calls? You will need lawful intercept capabilities. This is not all of it... By the time you are done, it will be easier to pay for a cell phone service.

Well I'll be a meta-mod-threader

[marcus]

It's nice to see that someone else has come up with the same "filter" that I have. We must have asked the same question.

How do you find interesting threads on /. these days?

Re:Watch out ISPs...

[Anonymous Coward]

ummm. not everybody can afford multiple DS3s. I doubt you could make a dent against an isp if your backbone is a dialup or a capped cable connection. Good luck though,Your upstream will love you for it.

Re:Wi-Fi all hype no action? Look at Intel &

[Anonymous Coward]

Intel is about to release a new laptop-specific processor called banias. It will have better power management so that your batteries will last 8 hours. Also, Intel is planning on integrating 802.11 a and b into their chipsets. There will be 30,000,000 new Wi-Fi ready laptops out on the market soon.

Mirosoft has just released their 802.1x client which is already in XP for their older operating systems win98, winNT4, winME... You will find that the security story will be solved here real soon. Someone will have to release an 802.1x client for Linux and Apple. The security problems will be all but forgotten soon.

WA4OSH

Asymetric stream used

[Anonymous Coward]

I do not understand how the gain on the antenna is not asymetric, since the client does not have a special antenna for tx?
Moreover, the stream that was used on the demo was highly asymetric in the IP level at least, UDP probably, MP3 stream with out any serioucs requirements for return channel.

Last Post!

[alpg]

The last time somebody said, "I find I can write much better with a word
processor.", I replied, "They used to say the same thing about drugs."
-- Roy Blount, Jr.

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