Beta

×

Welcome to the Slashdot Beta site -- learn more here. Use the link in the footer or click here to return to the Classic version of Slashdot.

Thank you!

Before you choose to head back to the Classic look of the site, we'd appreciate it if you share your thoughts on the Beta; your feedback is what drives our ongoing development.

Beta is different and we value you taking the time to try it out. Please take a look at the changes we've made in Beta and  learn more about it. Thanks for reading, and for making the site better!

High-Gain Patch Antennas Boost Wi-Fi Capacity In Crowded Lecture Halls

Soulskill posted about 9 months ago | from the it-all-comes-down-to-focus dept.

Wireless Networking 104

An anonymous reader writes "To boost its Wi-Fi capacity in packed lecture halls, Georgia Institute of Technology gave up trying to cram in more access points with conventional omni-directional antennas, and juggle power settings and channel plans. Instead, it turned to new high-gain directional antennas. They look almost exactly like the bottom half of a small pizza box, and focus the Wi-Fi signal from the ceiling-mounted access point in a precise cone-shaped pattern, covering part of the lecture hall floor. Instead of the flaky, laggy connections, about which professors had been complaining, users now consistently get up to 144Mbps (if they have 802.11n client radios). 'Overall, the system performed much better' with the new antennas, says William Lawrence, IT project manager principal with the university's academic and research technologies group. 'And there was a much more even distribution of clients across the room's access points.'"

cancel ×

104 comments

Sorry! There are no comments related to the filter you selected.

If WiFi is necessary for the lectures, (2)

John.Banister (1291556) | about 9 months ago | (#45342689)

why cram all the bodies into the hall?

Re:If WiFi is necessary for the lectures, (1)

rally2xs (1093023) | about 9 months ago | (#45342717)

To be able to converse with the professor?

$591.25 a pop, for the antenna alone ! (4, Interesting)

Taco Cowboy (5327) | about 9 months ago | (#45342971)

I read TFA, and did a search on that "bottom of pizza box" antenna.

Found it @ http://www.terra-wave.com/shop/font-colororangenewfont-245-ghz-14-dbi-high-density-panel-antenna-with-nstyle-jack-connectors-p-2993.html [terra-wave.com]

The only problem is the price.

The cost of the antenna alone is $591.25 a pop.

Perhaps Georgia Institute of Technology has a big endowment, that they can afford to install such devices all over their campuses.

For most private enterprises, on the other hand, it's simply not affordable.

Re:$591.25 a pop, for the antenna alone ! (5, Interesting)

wadeal (884828) | about 9 months ago | (#45343347)

(Involved in various facets of WiFi Projects for approx. 50 commercial sites).

Any commercial grade AP is going to cost you around the $500 mark. At the least.

Your point?

Re:$591.25 a pop, for the antenna alone ! (2)

datapharmer (1099455) | about 9 months ago | (#45343559)

While I concur about the general pricepoint, there are cheaper alternatives that are still perfectly good:
Ubiquiti: https://store.ubnt.com/unifi.html [ubnt.com] (all under $500)

Re:$591.25 a pop, for the antenna alone ! (0)

Anonymous Coward | about 9 months ago | (#45346745)

Any commercial grade AP is going to cost you around the $500 mark. At the least.

Wut?

https://store.ubnt.com/unifi.html [ubnt.com]

Re:$591.25 a pop, for the antenna alone ! (1)

pedrop357 (681672) | about 9 months ago | (#45347801)

Sure. But the OP mentioned the ANTENNA, not the AP.

I would have a serious problem paying $600/antenna in addition to the 500-700 per AP.

Re:$591.25 a pop, for the antenna alone ! (1)

Anonymous Coward | about 9 months ago | (#45343381)

$500 not affordable? For a bunch of people who just dropped more than that on iphones?

Uh... yeah.. ok sure.. whatever.

Re:$591.25 a pop, for the antenna alone ! (1)

pedrop357 (681672) | about 9 months ago | (#45347809)

Are the people using the phones paying for the Wifi antennas?

Re: $591.25 a pop, for the antenna alone ! (0)

Anonymous Coward | about 9 months ago | (#45349147)

Yes, it's called tuition.

Re:$591.25 a pop, for the antenna alone ! (1)

The Mighty Buzzard (878441) | about 9 months ago | (#45349741)

That may very well be why it's not affordable.

Re:$591.25 a pop, for the antenna alone ! (1)

Anonymous Coward | about 9 months ago | (#45343415)

Don't be silly. Enterprise kit is priced also because if done well the need for an expensive human to tend it goes down a lot -- despite often being complex and versatile pieces of kit. Of course, the margins are still quite huge and in that sense certainly overpriced.

But still worth it in the enterprise environment. There is a reason the likes of cisco can get away with 90%+ margins on hardware AND gouge you for support contracts. Compare and contrast how OpenWRT takes $60 consumer crap and gives it $600+-priced enterprise features. Not all features under the sun, but enough to make it worthwhile. Yet they haven't taken the enterprise world by storm. They haven't even seriously dented the prices of the expensive, or even "entry level enterprise" offerings. How come?

Even so, there are certainly cheaper options, as there should be. It's in fact amazingly cheap to come up with an antenna reflector that fits on a simple 2dBi stick omni and gives you, say, a 40deg x 60deg pattern and about 8dBi extra gain in that direction. Simply increasing signal strength on one side and not the other already limits the spread and reduces interfecence a lot. Plus, better antennae don't just give you better signal, they hear better too -- in contrast to just upping the wattage.

So, antennae really should be the first thing to consider when dealing with deployment problems. That this often isn't the case indicates that the "engineers" doing this sort of thing have too little domain knowledge and are thus often wasting their (expensive) time. If they'd do that less, there'd be demand for more varied palette of antennae, and their price would come down.

The price then points us to a deeper and more profound wtf. One that isn't quite explained by the fact that altough antennae can be (and often are) really simple in terms of material and construction, but still quite hard to get "just right", due to the math and precision engineering and expensive test setups required.

Re:$591.25 a pop, for the antenna alone ! (1)

citizenr (871508) | about 9 months ago | (#45343473)

Re:$591.25 a pop, for the antenna alone ! (4, Informative)

datapharmer (1099455) | about 9 months ago | (#45343487)

Only problem is where you shop. Not to plug newegg, there are many other cheap(er) venders you can probably find this at too, but just to prove a point:

$43 shipped: http://www.neweggbusiness.com/product/product.aspx?item=9b-33-993-021 [neweggbusiness.com]
$66 shipped: http://www.neweggbusiness.com/product/product.aspx?item=9b-33-978-030 [neweggbusiness.com]
$80 shipped: http://www.neweggbusiness.com/product/product.aspx?item=9b-33-993-022 [neweggbusiness.com]


I imagine if you are buying for a large institution you have a vendor that offers volume discounts as well, so they should in theory be paying even less than this.

Re:$591.25 a pop, for the antenna alone ! (3, Interesting)

evilviper (135110) | about 9 months ago | (#45343539)

I read TFA, and did a search on that "bottom of pizza box" antenna.
[...]
The cost of the antenna alone is $591.25 a pop.

So just because the first place you found the antenna, is selling it for $600, you assume that's actually the going rate they paid for it?

I wonder how many people bought this $23 million book about flies:
http://www.michaeleisen.org/blog/?p=358 [michaeleisen.org]

Re:$591.25 a pop, for the antenna alone ! (2)

necro81 (917438) | about 9 months ago | (#45343921)

Perhaps Georgia Institute of Technology has a big endowment, that they can afford to install such devices all over their campuses.

For most private enterprises, on the other hand, it's simply not affordable.

Most private enterprises have no need of this technology, because they don't have so many wireless clients packed into one location. Even the most happenin' Starbucks is an order of magnitude less dense than a lecture hall. This kind of technology would have application in crowded places that also have open sight lines. Airports are one example.

(The problem in airports, however, is that while you have crowds of people and relatively open spaces, all the people are on the move, so you would end up with lowered throughput because you'd be constantly walking in and out from each WAP's antenna coverage.)

and as for cost, well: it's infrastructure on a much bigger scale, with more stringent requirements, than most people deal with.

Re:$591.25 a pop, for the antenna alone ! (1)

MMC Monster (602931) | about 9 months ago | (#45344029)

Convention centers seem a better fit.

People do wander about convention centers, but not run from one end to the other.

The centers I've been to have excellent wifi. They probably already hired a good network engineer.

Re: $591.25 a pop, for the antenna alone ! (0)

Anonymous Coward | about 9 months ago | (#45344459)

Hmm. Not sure you've been in an airport. Most people are mobile until they find their gate at which time they become quite non-mobile, sometimes for an hour or more.

Re: $591.25 a pop, for the antenna alone ! (3, Informative)

kenh (9056) | about 9 months ago | (#45343989)

What do you imagine each unneccessary AP they deployed cost? If such an antenna costs as much as one displaced AP and provides a better signal, it's money well spent.

Re:$591.25 a pop, for the antenna alone ! (0)

Anonymous Coward | about 9 months ago | (#45344327)

For most private enterprises, on the other hand, it's simply not affordable.

Most enterprises don't have 200+ seat auditoriums that are regularly packed. I know of a school that has a 1700+ seat auditorium for some classes (which in the spring is used for graduation ceremonies).

Re:$591.25 a pop, for the antenna alone ! (1)

FooAtWFU (699187) | about 9 months ago | (#45346627)

Geez. You could buy an Aruba AP-93 Instant for that price, and it comes with a cone-antenna built in.

Re:$591.25 a pop, for the antenna alone ! (0)

Anonymous Coward | about 9 months ago | (#45347071)

I read TFA, and did a search on that "bottom of pizza box" antenna.

Found it @ http://www.terra-wave.com/shop/font-colororangenewfont-245-ghz-14-dbi-high-density-panel-antenna-with-nstyle-jack-connectors-p-2993.html [terra-wave.com]

The only problem is the price.

The cost of the antenna alone is $591.25 a pop.

Perhaps Georgia Institute of Technology has a big endowment, that they can afford to install such devices all over their campuses.

For most private enterprises, on the other hand, it's simply not affordable.

I promise you that one 3-year quote from a managed service provider to discuss their "next-gen managed wifi service" will result in that ~$600 price tag looking like peanuts very quickly.

All depends on how you sell your upgrades.

Re:If WiFi is necessary for the lectures, (1)

John.Banister (1291556) | about 9 months ago | (#45350895)

Every time I was in a crowded hall and someone tried that, it was hard for the student to be heard by the professor, next to impossible for students further out to hear, and by the time the interaction completed, I was often wondering if it was worth everyone else's time to have sat through the one person's words and the response to them. I can see the benefit of a large crowded hall if the school is maximizing the use of the time of a visiting guest lecturer. I went to a couple such symposiums I'm very glad to have attended. But, in that sort of case, I'd never be paying attention to the connected device, only to the person speaking.

why are big lectures classes necessary (0)

Joe_Dragon (2206452) | about 9 months ago | (#45342739)

When an on line video with DRV controls and notes are much better.

Re:If WiFi is necessary for the lectures, (2, Funny)

Anonymous Coward | about 9 months ago | (#45342745)

Hey Grandpa, is that you?

Re:If WiFi is necessary for the lectures, (4, Insightful)

MrEricSir (398214) | about 9 months ago | (#45342757)

Sometimes it's useful to look something up online, test a formula, or download notes so you can understand the material better and ask informed questions.

Regardless, it's less distracting if everyone's wifi just works (TM) than for students to be spending more time messing with their wifi configuration than listening to the lecture.

Re:If WiFi is necessary for the lectures, (1)

Darinbob (1142669) | about 9 months ago | (#45348443)

Do that later. Maybe the prof can look something up. Maybe one or two students. But to require wifi connectivity continually for every single student in the lecture is misguided. That's anarchy. If students don't want to be there or think that it's a waste of time then they can just fork over their thousands of dollars and stay home.

Now start working on something to block wifi in lecture halls instead.

Re:If WiFi is necessary for the lectures, (1)

noh8rz10 (2716597) | about 9 months ago | (#45342927)

facebook

Re:If WiFi is necessary for the lectures, (1)

nojayuk (567177) | about 9 months ago | (#45343497)

To absorb the RF energy -- b/g/n Wifi is very close to the frequency used in microwave ovens and so it's optimised to heat up meaty tissue (and vegetables too; this is Georgia Tech we're talking about, isn't it?)

Re:If WiFi is necessary for the lectures, (0)

Anonymous Coward | about 9 months ago | (#45344769)

I also had the microwaves in mind. How apt that they compare the antennas to pizza boxes.

they couldn't find old Pringles cans? (1)

swschrad (312009) | about 9 months ago | (#45345679)

or old satellite TV antennas?

News? (5, Insightful)

Andhesaidtome (2738249) | about 9 months ago | (#45342763)

It is hardly newsworthy that a group of IT network techs 'fixed' their coverage and performance problems using directional antenna technology. Radio techs have been doing exactly that since they learnt about propagation. A newsworthy story would be that they have (finally) started incorporating at least basic RF theory in all IT networking related courses and subjects.

More like Slashvertisment (2, Interesting)

infernalC (51228) | about 9 months ago | (#45342853)

This is a parroting of a marketing-derived press release. Move along. I think I'm going to move along. Thanks for the memories, Slashdot.

Re:News? (0)

Anonymous Coward | about 9 months ago | (#45342981)

Yeah, how exactly is this news. Maybe its just me. Before getting a BScCS, I got an AD in Electronics Engineering. Antenna radiation theory and propagation was well on the bill (LF/HF/VHF/UHF/Radar). Sure there was also fiber optics, waveguide, logic gates, active filters, more calculus than I think I will ever (again) need in my life, control systems, Laplace, Fourier and Z transforms. About 2 years ago I built a nice ganged antenna to get very nice digital TV (calculated free space loss, looked at Bode plots, etc.), and looked at the different encoding done for the signal (both Reed-Solomon and Trellis encoding... its all digital), and I've also extended the range of my wifi router antennas, and also looked at the high gain 'Cantennas' used to get wifi from more than 10 miles. And this bunch were 'surprised' about using a (single) reflector to enhance gain of their wifi in a single direction? How exactly little do these people actually know about the technology they are using? Its kinda sad.

Re:News? (4, Funny)

Gravis Zero (934156) | about 9 months ago | (#45343067)

It is hardly newsworthy that a group of IT network techs 'fixed' their coverage and performance problems using directional antenna technology.
Radio techs have been doing exactly that since they learnt about propagation.

so... does this mean you aren't interested in the story about how they replaced the batteries in the remote?

Re:News? (0)

Anonymous Coward | about 9 months ago | (#45344125)

I read with awe how they slid off the back cover. It was riveting!

Re:News? (1)

Anne_Nonymous (313852) | about 9 months ago | (#45344735)

>> so... does this mean you aren't interested in the story about how they replaced the batteries in the remote?

Maybe the batteries are dead? DNRTFA.

Re:News? (0)

Anonymous Coward | about 9 months ago | (#45343143)

A newsworthy story would be that they have (finally) started incorporating at least basic RF theory in all IT networking related courses and subjects.

Good news! My local community college has two classes in wireless networking. One for LANs and another for WANs, microwave, satellite links, and so on. Which one you can take is dependent on how many calculus credits you have. Does that qualify?

If you really want a formal technical education, go to a school that focuses on application, not an institution that gives out pieces of paper if you hang around long enough.

That and this is like 70-80 year old tech (1)

Zeorge (1954266) | about 9 months ago | (#45344509)

The concepts of antenna radiation patterns and propogation has been fairly well understood for quite some time now.

Re:News? (3, Insightful)

bananaquackmoo (1204116) | about 9 months ago | (#45344745)

I take it you've never actually been to a crowded lecture hall or conference room? There are thousands of these things with administrators that have no clue about this idea. It IS news to many people who are responsible for this exact sort of thing. It may not be news to you, but there have been many times where I was in a crowded area where I would kill for wifi, but it wouldn't work due to crowding.

Re:News? (0)

Anonymous Coward | about 9 months ago | (#45349827)

So it's newsworthy showing people that work on IT something that was news more than 5 years ago, because some of them still don't know how to do it?

Go Slashdot!

Re:News? (1)

Andhesaidtome (2738249) | about 9 months ago | (#45350981)

I have, lamenting each time that our education system is releasing Network Admins into the wild with no RF knowledge. The story should have been...

We have now realise the error of our ways and are introducing compulsory RF Theory subjects to all our Networking courses.

Of course as others have said this is more marketing 'case study' by the antenna vendor than story. Notice TFA mentions that they did test antennas from other vendors, but give no indication of the relative performance. My bet is that most would be within the margin of error and that the ultimate choice came down to the discount they received for pushing out the 'case study' as news.

Radiated power? (4, Informative)

jhol13 (1087781) | about 9 months ago | (#45342819)

In Europe we limit the maximum radiated power (EIRP). This means you'd have to drop TX power and the directional antenna helps on RX only. Still might be worthwhile.
Although there is ample proof that WiFi don't have health issues, I still want to limit the EIRP. But to what level, I do not know. I think directional antennas currently have too strict a limit - you are not supposed to be standing next to a directional antenna anyway. OTOH people hardly understand what a 20dB antenna does (in TX).

Re:Radiated power? (1)

Z00L00K (682162) | about 9 months ago | (#45342865)

Even with lower power a directional antenna will lower the interference from other cells so it is definitely worth it.

Re:Radiated power? (1)

jhol13 (1087781) | about 9 months ago | (#45352579)

Good point, I didn't think of interference at all, never have had to deal with it myself.

Re:Radiated power? (1)

MightyMartian (840721) | about 9 months ago | (#45342875)

And what do you have, photon police that go around the EU hunting for people pumping more dB than is allowed?

Re:Radiated power? (0)

Anonymous Coward | about 9 months ago | (#45343175)

Yes, we do.

Re:Radiated power? (0)

Anonymous Coward | about 9 months ago | (#45343485)

the German photon police is called Bundesnetzagentur (formerly called RegTP) and they have measurement equipments, antenna-laden vans and the authority to fine you for violations of applicable regulations. Needs more antennas IMHO - doesn't look menacing enough. http://commons.wikimedia.org/wiki/File%3ARegtp_Antennenwagen.jpg

Re:Radiated power? (0)

Anonymous Coward | about 9 months ago | (#45345049)

These regulatory folk, I don't mind them if they hit you with a modest fine, that after a few times, you get annoyed and finally rectify the issue.

What I have a severe problem is with every regulatory agency forming their own little Stasi to go around and threaten/harass people with heavy fines, and the "piling on" of supposed offenses (there's thousands of regulations/laws/ordinances added every year, and everyone is guilty of something, just allow a bureaucrat who produces nothing, to go poking around), which is what we have here in America.

Re:Radiated power? (0)

Anonymous Coward | about 9 months ago | (#45343509)

The average background radiation does more damage to your body in half a year than any radiation from these would do across several years at high intensity on an average school year.
I hardly see a problem. Using A computer does more damage to you alone!

Re:Radiated power? (1)

Sockatume (732728) | about 9 months ago | (#45343729)

That doesn't change the underlying legal and regulatory barrier, though.

Re:Radiated power? (1)

jhol13 (1087781) | about 9 months ago | (#45352545)

With the antennas mentioned in the article, I agree.
But for an example with +30dB antenna you could burn yourself. 1W +30dB is on the same ballpark as UNSHIELDED 1kW microwave oven.
Sure, 30dB antenna is difficult to make, but 1W with 20dB should stay illegal.

Re:Radiated power? (0)

Anonymous Coward | about 9 months ago | (#45343883)

In Europe we limit the maximum radiated power (EIRP). This means you'd have to drop TX power and the directional antenna helps on RX only.

It is a PASSIVE microstrip patch antenna. The gain adds to the TX as well as the RX.

Re:Radiated power? (2)

foobar bazbot (3352433) | about 9 months ago | (#45344619)

It is a PASSIVE microstrip patch antenna. The gain adds to the TX as well as the RX.

The law doesn't care what sort of antenna it is -- the law specifies a maximum EIRP, and if you're already at that EIRP with a 6dB omni, your legal options are either (1) don't use a 12dB patch or (2) reduce your transmit power by 6dB to have the same EIRP.

In the US, at least, the FCC recognizes the benefit of highly directional antennas in that they reduce interference with other networks in the same channel, in every direction except where they're pointed, and therefore has established a "reward" for using them by permitting more EIRP with higher-gain directional antennas (ISTR for each 3dB of antenna gain, you get 1 dB more EIRP allowed, so you only have to decrease tx power by 2dB -- or something like that).

However, this only applies to fixed point-to-point links -- an AP with multiple portable/mobile clients doesn't count, and has a fixed maximum EIRP, just like in Europe, no matter what antenna you use.

Re:Radiated power? (2)

foobar bazbot (3352433) | about 9 months ago | (#45344697)

The directional antenna on AP A only helps AP A on receive, not transmit.

However, there's substantial benefits in both receive and transmit when you change all the antennas from omnis to patches: The directional antennas on APs B, C, D and E prevent their transmissions from interfering with AP A's transmissions to AP A's clients, and likewise the directional antenna on A helps B, C, D, and E.

Re:Radiated power? (1)

WolfWithoutAClause (162946) | about 9 months ago | (#45346893)

Actually the directional antenna helps with both RX and TX directionality and power equally; and there's almost certainly an attenuator that offsets the aerial's gain.

It doesn't help with the power coming from the laptop/tablet, but that's pretty small; some laptops will have gain control on their transmitters as well.

EIRP regulated in US (1)

CaptainNerdCave (982411) | about 9 months ago | (#45347597)

This is similar in the US, but it varies slightly based on frequencies, locations, and environment.

FCC Certification (1)

Anonymous Coward | about 9 months ago | (#45342867)

Plugging in that antenna invalidated the FCC certification of the AP

Georgia Tech are breaking the law!

Using the right equipment makes life easier (1)

Osgeld (1900440) | about 9 months ago | (#45342869)

News at 11

Genius! (0)

Anonymous Coward | about 9 months ago | (#45342885)

Wifi antennas concealed inside the elbow patches on the lecturers tweed jacket! What a great idea.

"New" high gain antennae? (1)

toygeek (473120) | about 9 months ago | (#45342893)

I think its funny how the summary says this like its some new fantastic technology. Directional gain antennae have been around almost since radio itself. There's nothing new about this, and if I had to guess, the ham radio club at Georgia Tech has been telling them to use directional antennae for a while now. Somebody with the authority to enact it managed to convince themselves that they though of it, did it, and now we're supposed to be impressed.

Re:"New" high gain antennae? (2)

sbrown7792 (2027476) | about 9 months ago | (#45342961)

Well, they're "new" in the sense that they just purchased them, and knowing how much red tape there can be at universities, I'd say that is something to be impressed at.

Re:"New" high gain antennae? (5, Insightful)

CaptQuark (2706165) | about 9 months ago | (#45342969)

Directional antennas are not new. But configuring an array of directional antennas to precisely cover the seats in the lecture hall to minimize the number of users on any single access point is a new and novel way to deploy wireless access.

Deploying the same number of omnidirectional antennas in the same space would lead to massive overlap, interference, and clients unnecessarily switching between APs when they perceived a stronger signal from a different AP.

I haven't heard of a high density environment purposely set up this way therefor I think it is indeed newsworthy.

~~

Re:"New" high gain antennae? (0)

Anonymous Coward | about 9 months ago | (#45342993)

All directional antennas, with the exception of a simple reflector, use arrays of antennas/stubs for gain.

This *really* isn't new, unless it's some smart antenna.

Re:"New" high gain antennae? (2)

thegarbz (1787294) | about 9 months ago | (#45343355)

You're just saying that with your IT hat on. The reality is whenever you start doing some tricky stuff just hand over to the RF guys and they can do precisely this kind of coverage work with their eyes closed. It's quite basic to build a system like this, IFF you know what you're doing.

Re:"New" high gain antennae? (0)

Anonymous Coward | about 9 months ago | (#45346345)

2011:
http://www.cisco.com/web/strategy/docs/education/cisco_wlan_design_guide.pdf

Re:"New" high gain antennae? (1)

aXis100 (690904) | about 9 months ago | (#45351729)

It's neither new nor novel, it's just that most low end IT installers havent thought about it before.

It's exactly the same way they deploy mobile cell towers - multiple directional antennas each covering a fixed arc.

Are you serious? (4, Insightful)

Mr. Freeman (933986) | about 9 months ago | (#45342929)

URGENT! URGENT! URGENT!
DISTRIBUTION: ALL STATIONS
MESSAGE READS:
IT guys fix their spotty wireless coverage by installing the proper antennas.
END URGENT MESSAGE

Wow, thank God for that. Good thing that we have slashdot to tell us that a university installed some standard equipment on their campus. Be sure to run an article when MIT replaces a couple of their switches next month.

Re:Are you serious? (2)

Sockatume (732728) | about 9 months ago | (#45343733)

Yes, obscure technical information has no place on a site that claims to provide "news for nerds".

Re:Are you serious? (0)

Anonymous Coward | about 9 months ago | (#45345953)

Lol @ "obscure technical information"

It's a standard product. It might have been news if they rolled their own with some help from the EE dept.

Re:Are you serious? (0)

Anonymous Coward | about 9 months ago | (#45348379)

> when MIT replaces a couple of their switches next month

I'm pretty sure MIT replaces a light switch at least every month. Check with their maintenance department.

Lecture Halls are for listening to the Professor (0)

Anonymous Coward | about 9 months ago | (#45342941)

Wi-Fi is an inappropriate distraction. Lecture is for listening. How else are you going to learn about the mathematics of wonton burrito meals?

Barack Bush does not care (-1)

Anonymous Coward | about 9 months ago | (#45342979)

about black people in crowded lecture halls.

This is not news (1)

downundarob (184525) | about 9 months ago | (#45342983)

I was told by a ham radio operator back in the day that a radio setup is only ever as good as its antenna system (and that includes the coax and feedline) to me this simply sounds like they finally listened to the old man in the crew.

Underwhelmed (0)

Anonymous Coward | about 9 months ago | (#45343121)

Cisco does this regularly for installations in sports arenas. Hell, the current crop of access points does active beamforming per client. If the marketing material is to be trusted...

Been done for years (1)

Adrian Harvey (6578) | about 9 months ago | (#45343225)

Xirrus have been doing this for years - see http://en.wikipedia.org/wiki/Xirrus [wikipedia.org] or http://www.xirrus.com/ [xirrus.com]

They put 8 (or more) access points into a single unit, each with a directional antenna covering a segment of the room or venue. I looked at their product at a trade show or conference once (don't remember which) but it was way overkill for the spaces we had at the time which were separated with heavy reinforced concrete walls and floors, so needed an access point for each area.

any ham radio op knows (0)

Anonymous Coward | about 9 months ago | (#45343425)

that it's all about the antenna

100% WRONG! (0)

Anonymous Coward | about 9 months ago | (#45343743)

They look like the TOP half of the pizza box!!!

More purpose-designed wifi standards? (2)

swb (14022) | about 9 months ago | (#45343963)

It's always remarkable what people do with 802.11, but a lot of it strikes me as a mediocre standard being (over)extended with gimmicks.

Out of the box it works well enough for simple use, but more complex use cases (distance, density, broader coverage) seem to involve a lot of complexity to make up for the overall weakness of the standard (limited channel selection, radio power, etc).

Are there any changes on the horizon to generate new standards that would fix this? Such as designs tailored to high-density environments (hundreds or thousands of clients off a single radio), greater channel selections, better distance capabilities, etc?

I realize that not all of these may be something that works in a single product and that there are RF constraints that limit this, but at the end of the day the current 802.11 environment reminds me of DOS. Sure, with the right shims and magic you can run games (Quake, for the era) or a GUI OS on top of them, but there's something inherently hokey about it.

Re:More purpose-designed wifi standards? (1)

foobar bazbot (3352433) | about 9 months ago | (#45345289)

It's always remarkable what people do with 802.11, but a lot of it strikes me as a mediocre standard being (over)extended with gimmicks.

Out of the box it works well enough for simple use, but more complex use cases (distance, density, broader coverage) seem to involve a lot of complexity

Distance -- ye cannae change the laws of physics. You need one or more of: more power, more RF bandwidth, a higher gain antenna, or a coding system with less bits/s/Hz. Since you claimed power and bandwidth as problems below, I'll address them in a minute. You've already written off directional antennas as "gimmicks", and 802.11b already includes coding as low as 1Mb/s -- I don't think it's really worth putting even lower bitrates in the standard just so people can make >1 km links without having to spend $20 on a directional antenna.
Density -- this one is legitimately improvable by abandoning CSMA-CD (probably in favor of CDMA), but that's a big and complicating change to the standard to improve the minority of cases that actually have high density. I'd be receptive, in theory, but in practice, there's other ways to accomodate the few cases where this would be helpful, and I'm not sure how well you could make a CDMA-based WiFi standard interoperate with 802.11 WiFi in the same band (aside from just having two separate radios), and that sort of interoperability (like the way 802.11g supported 802.11b devices) is essential to getting the new standard phased in.
Other options (both commercially deployed already) are either TDMA-ish coordination amongst APs (which is an ugly gimmick, but does work, and importantly works with unmodified clients, only adding complexity to the infrastructure) or curtailing physical size of each AP's domain with directional antennas (as in TFA, again only requires changing infrastructure, and only in those cases where density is problematically high -- and it's not an ugly gimmick in any way I can see.)
Broader Coverage -- TANSTAAFL; this is the same as Distance, except you can't even use higher gain antennas.

to make up for the overall weakness of the standard (limited channel selection, radio power, etc).

Seriously? those are your weaknesses? Not CSMA-CD? Well, OK...
Limited channel selection -- turns out, the 2.4GHz band is pretty tiny and sucktastic. That's a function of the band, not the radio protocol, and nothing running in the 2.4GHz band is going to do a whole lot better with it than 802.11n does. However, this problem can be (and, it turns out has been) solved without abandoning 802.11, by just picking a different band. Behold, the 5GHz band used with 802.11a/n (and 802.11ac). Loads of non-overlapping channels!
Radio power -- seriously? Because apartment buildings don't have enough trouble with APs on the same channel screaming over each other? We'll just make them all louder? Seriously, there's nothing really wrong with increasing the power limits, but it solves very nearly zero problems. The only cases where you really want more power is long-distance links, which are a tiny minority anyway, and the difference there will usually be between an expensive very-high-gain antenna, and a slightly less expensive moderately-high-gain antenna. There's very little that an ordinary AP, with an ordinary antenna, can almost do, and thus could do if the legal limit was 5 or 10dB more.

Are there any changes on the horizon to generate new standards that would fix this? Such as designs tailored to high-density environments (hundreds or thousands of clients off a single radio), greater channel selections, better distance capabilities, etc?

Well, 802.11ac will only support 5 GHz band, thus putting 2.4GHz behind us once and for all (which 802.11n failed to do), but it won't do much for high-density or long distance. But it's still part of 802.11, not a "new standard", because there's really not near as much wrong with 802.11 as you seem to think.

Re:More purpose-designed wifi standards? (1)

swb (14022) | about 9 months ago | (#45345487)

Hey, I'm not an RF guy and fortunately the equipment these days (controllers + radios) take away a lot of the low-level complexity in a way that mostly works. But even then the 2.4ghz band blows in high-density office spaces like office towers. There's just too much competition and you can't do much about the 20 other visible radios, all blasting out at maximum power to try to overcome each other.

That being said, it does still feel like a system designed for casual use (ie, a single AP allowing clients within a small radius to access a network) that has used all manner of gimcrackery on the back end to be a does-all standard for distances beyond what it was envisioned for (ie, LoS P2P links), municipal wifi (trying to blanket an entire city) or super high densities or mixed radio densities (office buildings).

Jack of all trades, master of none.

Amazing discovery! (1)

kenh (9056) | about 9 months ago | (#45343983)

High gain directional antennas work better than low gain onni-directional antennas... Who knew?

Wasting 75% of your transmitted power by sending your signal out in a 360 degree radiation pattern instead of focusing all your power on a 90 degree 'wedge' is just stupid - I have to wonder who designed their wifi deployment, commission-based access point salesmen or results-oriented networking specialists?

Re:Amazing discovery! (1)

queBurro (1499731) | about 9 months ago | (#45344105)

so... if we all mounted our APs in the roof space with directional antenna pointed down we'd *all* have better wifi rececption. For me, my AP would be one layer of plasterboard worse off than where it is now (but with a gain from the antenna hopefully). I could use a Wok instead of an aerial change so it's cheap too.

Duh.... (1)

Lumpy (12016) | about 9 months ago | (#45344133)

This is exactly how high capacity AP's work. it has basically 4 (or more, I have seen some with 8) ap's that are connected to high gain antennas that segment off what they see. An advantage of high gain antennas is that they squish their signal and receive "window" into tighter lobes.

Honestly, if these people would take classes in RF design they would know this as the technology they are using has been around for decades, and the idea has been in use by companies covering large venues for at least a decade. The trick is the attenuation of the antennas' signal so you dont get a ton of reflections, you actually run that high gain antenna into an attenuator, plus you really crank down the power output for transmit.

How much can a Yagi bear? (1)

dbIII (701233) | about 9 months ago | (#45344201)

When slashdot started some of the first stories here were about WiFi with directional antennas (eg. the famous pringles can long links). Long before I managed to get on the actual internet (instead of just a mere BBS) I knew people that were doing things with microwaves and directional antennas (microwave point to point link from a community radio studio to an FM transmitter). So is this story really just about somebody that actually decided to read up and get a clue about what were are doing instead of blindly hoping something would work? I think the real story is that the bar is set so low that an IT project manager working out what a first year physics or engineering student could tell them is rare enough to comment on. There's even free software that can map the signal strength now.

Laugh (1)

koan (80826) | about 9 months ago | (#45344323)

What's the change in radiation exposure?

Re:Laugh (0)

Anonymous Coward | about 9 months ago | (#45344531)

probably small.

THe antennas are in the roof of a large building, and are "far" away from the people sitting under them. So the power density at the seats is probably lower than if you had a bunch of APs at ground level with omni antennas. Inverse square builds up pretty fast.

The other thing is that the person is probably receiving a higher dose from their own WiFi adapter(s) than from the AP:because of the inverse square law. Laptop with WiFi + Android/iPhone with WiFi and you've got two WiFi transmitters right next to you; blasting away at their nominal 100 mW. An AP with 100mW that's 10 meters away, even with a 20dBi antenna, is going to be a lot lower flux.

dedicated controller (1)

mounthood (993037) | about 9 months ago | (#45344681)

... a dedicated controller to handle the new “high density group” of access points; and the controller automatically handled configuration tasks like setting access point power levels and selecting channels.

Centralized management of the access points seems to be the solution, which doesn't require directional antennas to work.

Wow (1)

morgauxo (974071) | about 9 months ago | (#45344779)

I've been out of college for just barely over a decade but this is making me feel very old.

Re:Wow (1)

Darinbob (1142669) | about 9 months ago | (#45348517)

Remember when we sent a man to the moon, and none of those scientists involved had access to wifi in their college lecture halls. People created the atom bomb without wifi, the first open heart surgery had no wifi enabled devices assisting, and we wrested fire from the gods on Mount Olympus without even a carrier pigeon. So why is it today that college students are unable to attend a lecture without needing connectivity? Sure, someone says they want internet access so that they can look up the material and ask relevant questions - but we've been able to do that for centuries just by paying attention when someone else is talking. Have humans suddenly become stupid in the last decade?

What about clients (0)

Anonymous Coward | about 9 months ago | (#45345735)

This seems to help the APs focus their TX/RX, but what about the clients? When will we have clients/drivers(?) that automatically dial down their power and thus create less interference?

Re:What about clients (1)

aXis100 (690904) | about 9 months ago | (#45351859)

The client-clients interference doesnt matter so much. Close clients are on the same AP/Channel and are thus participating in collision avoidance. Mid distance clients are on a different channel and thus dont interfere. Long distant clients who are on a re-used channel are so far away the signal is small (essentially noise), and the signal of the access point dominates such that SNR is still good.

From the AP end the directional parttern the antenna works in both directions. They transmit to only a limited number of clients, and receive from only a limited number of clients. Anyone off-lobe is heavily attentuated and becomes part of the noise floor.

means that each AP only sees a limited number of clients transmitting. Any off-lobe clients are heavily attentuated.

{facepalm} (0)

Anonymous Coward | about 9 months ago | (#45345817)

I've been using patch antennas in my house for years.

Got them used off ebay for next to nothing.

Glad to see the best and brightest at an institute of higher learning are finally catching on.

{facepalm}

Someone should tell the cellphone companies (1)

FryingLizard (512858) | about 9 months ago | (#45347095)

...then they could use directional antennas on cell base-stations and divide up each cell into slices!!
Hey they could call them "sector antennas" and... oh never mind.

so Doing somthing properly (1)

mjwalshe (1680392) | about 9 months ago | (#45347519)

and in a professional manner works better than getting some intern who once set up a single ap for there parents to deploy a large scale wifi system - I am amazed i though wifi had magic unicorns that made it perfect!
Load More Comments
Slashdot Login

Need an Account?

Forgot your password?
or Connect with...

Don't worry, we never post anything without your permission.

Submission Text Formatting Tips

We support a small subset of HTML, namely these tags:

  • b
  • i
  • p
  • br
  • a
  • ol
  • ul
  • li
  • dl
  • dt
  • dd
  • em
  • strong
  • tt
  • blockquote
  • div
  • quote
  • ecode

"ecode" can be used for code snippets, for example:

<ecode>    while(1) { do_something(); } </ecode>