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Wi-Fi VoIP At 80 mph

timothy posted more than 9 years ago | from the 130-km/h-in-mexico dept.

Wireless Networking 142

fredo123 writes "Almost faster than a speeding bullet. As reported in Muniwireless minutes ago, RoamAD and WI-VOD have tested mobile VOIP over Wi-Fi at over 130 Km/h over an 8km stretch of Interstate highway somewhere near the Mexican border. Gee... I wonder what this is for?" No need to guess: according to the MuniWireless link, "the network is for public safety personnel (police, fire, ambulance and border patrol) first, with various community agencies, schools, business and local residents being added as the deployment expands beyond its targeted coverage areas."

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142 comments

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...i had to say it (4, Funny)

r84x (650348) | more than 9 years ago | (#11750749)

All hail the Information Superhighway!

Re:...i had to say it (1)

SirXavier (861670) | more than 9 years ago | (#11750798)

it`s very good because VOIP & whireless is simple and the best !

Re:...i had to say it (-1, Redundant)

Anonymous Coward | more than 9 years ago | (#11751041)

And just think what life would be like today if Al Gore was elected President!

In Other News... (1)

Delta2.0 (846278) | more than 9 years ago | (#11751724)

13 people die in a 7 car pileup due to a man playing Unreal Tournament online while going 80

Security? (3, Interesting)

networkBoy (774728) | more than 9 years ago | (#11750754)

VOIP and wireless, now the Drug runners cn listen in on conversations. Remember some of the bigger cartels are funded as well as governments.
-nB

Re:Security? (2, Insightful)

temojen (678985) | more than 9 years ago | (#11750765)

It's sooo much easier to eavesdrop with a police scanner.

Re:Security? (1)

Cthefuture (665326) | more than 9 years ago | (#11750965)

Maybe this is exactly why they are looking at VOIP. VOIP is a lot easier to encrypt and secure than cellphones.

I still wonder why they don't just use cellphones though. They would probably be a lot more reliable due to the huge infrastructure already present.

Although I like VOIP, if I go by my own experiences using it, I can say it's not as realiable as the regular old phone system. VOIP needs a lot more technology to make it work. Eventually I see it as being better than the old phone system, but we are a ways off from that right now.

Re:Security? (1)

ChuckSchwab (813568) | more than 9 years ago | (#11751589)

Don't be ridiculous. The government is superior to all of the cartels combined. Imagine a war, government against drug cartels. So they're holed up in a house with a dozen hostages? Slam an anti-tank missile through the window. So they've set up a strong-point protected by nests of machine-guns? Napalm the block. So their shoulder-launched anti-aircraft missiles are threatening our helicopter gunships? Call in an artillery strike from twenty miles away. The only reason the cartels are even around is because the government lets them.

Re:Security? (1)

Various Assortments (781521) | more than 9 years ago | (#11751862)

*chuckle*

kids these days, they watch a few spy movies and they think their technological armies are infallable.

i've got news for you, sparky. each of those high-tech toys they hold in such high esteem have vulnerabilities you could drive a guerilla troop carrier through. thanks to the fact that americans can never keep their yaps shut whenever they develop a new battle technology, that information is quickly disemminated to the general public.

guerilla war will ALWAYS triumph on native soil.

Re:Security? (1)

ChuckSchwab (813568) | more than 9 years ago | (#11751989)

guerilla war will ALWAYS triumph on native soil. Only because their governments give them rules of engagement that prevent them from ever winning. Start allowing torture and public executions of insurgents and watch their numbers dwindle.

Re:Security? (0)

Anonymous Coward | more than 9 years ago | (#11752053)

Yeah, that worked really well for the Nazis in France.

Re:Security? (1)

ChuckSchwab (813568) | more than 9 years ago | (#11752180)

It did the job.

...why? (3, Insightful)

Anonymous Coward | more than 9 years ago | (#11750755)

Why not just get them normal cell phones or something?

Re:...why? (2, Insightful)

XorNand (517466) | more than 9 years ago | (#11751107)

My guess that it's less costly than buying cell phones for everyone and then having to pay for airtime ontop of that. Plus it would be easier for that to record, log, etc. calls from HQ, regardless of who the officer calls.

Re:...why? (2, Insightful)

chia_monkey (593501) | more than 9 years ago | (#11751130)

There are a few reasons they could be trying this. One, they can deploy and control their own private network. This gives them more control over what kind of equipment they can use, how they use it, etc. Also, perhaps cell coverage blows in this area but setting up their WiFi network gives them full coverage. Also, with such network, they can also have their laptops or PDAs in the car to connect with the network and transmit valuable data (records, news flashes, etc) back and forth.

Re:...why? (1)

Preeminence (784375) | more than 9 years ago | (#11751141)

You need internet to get background checks, run license plate numbers, etc. The chase becomes very different if you're behind a known drug runner.

Three letters Q.o.S (2, Interesting)

PaulBu (473180) | more than 9 years ago | (#11751194)

Over IP it is "easy" (as in, standards exist) to support Quality of Service bits, and you can bet that police voice chat will get higher priority than some traveler's connection to maps.google.com.

In cell phone network _maybe_ something like this is possible, but it would not be that easy to adjust in real time, I'd guess...

A friend of mine told me that when he was stuck in really bad traffic on I5 (he used to commute LA to San Diego) his cellphone was almost useless exactly because everyone else was also trying to call home...

Paul B.

Illegal to drive using a cellphone... (1)

EmbeddedJanitor (597831) | more than 9 years ago | (#11751363)

in some countries. VoIP is fine though :-).

Cops and Cell Phones (4, Interesting)

ebooher (187230) | more than 9 years ago | (#11751366)

In response to your statement about giving cops cell phones instead of a WiFi VoIP based solution. I'd like to add my opinion to the argument. Everyone ready?! It is time once again for my Bullshit Theory of the Day . (Patent Pending, of course.)

Let's review what the police already use to their job. Every officer where I live, be they local, county, or state, has a laptop in their car. Their radio system is trunked and the laptop receives information from the station as well as offering multiple channels for voice communication to dispatch. At this time the technology, though having been in use for a while, is still somewhat proprietary and thus is expensive. A station must buy the trunking hardware to digitize, and mux traffic, then transmit that into the ether where it is picked up by everyone.

Let's review that last word. Everyone. Where I live it is illegal to have a police scanner in a moving vehicle. (Technically, during transport ie you just bought it, the scanner must be in the trunk.) There really isn't anything to keep normal people, as well as criminals, from listening to communications. At best, the consumer scanners don't have the proper computer communication from headquarters and most sometimes can't follow a full conversation. (The trunks switch every mic key release, and the "computer" channels change every couple of days.) But you typically can hear what you need to in order to know where your friendly neighbor Officer Mitchell is doing his job.

Also, pushing information like that through the ether can be hit or miss in rural communities. You have to remember, that the curvature of the Earth dictates distance for RF travel. Typically 70 miles before you hit the ground itself, unless you get the signal on a high tower. However, the trunk receiver on the cars can't be equally as high (and I'm starting to wondering if satellites are not getting involved. The trunk receivers now look like XM antennas) anyway, I digress. This means, technically, that unless you are bouncing the signal to orbit and back you can not talk to a field agent that is over 70-ish miles from home base.

Enter tomorrows technology today. Setting up WiFi that allows vehicle transmission to push VoIP so that as long as you have an internet link, you can communicate with dispatch. This will not be limited to voice. The laptops the officers use to get information about plates and criminals will also switch to this WiFi based system, and for the Law Enforcement Pointy Haired Bosses, here comes the best part. PGP type encryption for PTP tunnel building so that the information between agent and base is "secure". Technically, it would take someone long enough to get the encrypt key, even if it's measured in minutes, to keep from knowing exactly when and where officer movement is occuring real time.

The funny thing is that I used to do tech support for Motorola, and they have a wireless networking technology that is pretty cool. We also did tech for their international customers, and had this one crazy chick from China continuously calling. Had to be two or three times a week, for about four months. Asking all kinds of technical and really out there questions about the system, and why the system didn't work. We puzzled through it and finally got an interpreter involved and found out she had these things on *trains* Apparently Asian WiFi has already been doing this moving hand off for a while now, at least experimentally. The Chinese chick couldn't understand that this product was like ethernet cabling, without the cable. Had to be aimed and left. So the control center kept losing, and then regaining, contact to trains on board systems. So people want this to work, for a variety of reasons.

I can't even begin to tell you how often I look and listen to what is going on without thinking to myself, "My God, we're in a badly ghostwritten William Shatner novel." ... or any other post apocalyptic work that envisions the future of the world with computers in our head. Ever hear of Masamune Shirow? I'm starting to think that dude is dead on about what's coming in the next 50 years.

FP (-1, Offtopic)

Anonymous Coward | more than 9 years ago | (#11750756)

And now for something completely different...

Re:FP (-1, Offtopic)

Anonymous Coward | more than 9 years ago | (#11750897)

You being a n00b fucktard isn't different, and you even failed at that... Sorry! Now back to detention with you!

And so what if it is? (-1, Offtopic)

Anonymous Coward | more than 9 years ago | (#11750758)

Do Mexicans have some divine right to ignore the laws of other countries?

Yes (-1, Offtopic)

Anonymous Coward | more than 9 years ago | (#11750779)

The pope said so

Re:Yes (-1, Offtopic)

Anonymous Coward | more than 9 years ago | (#11750870)

Yeah... Catholics are funny that way. They preach a lot of selflessness as long as it's other people being selfless. Nice of them to appoligize for the church's actions in WWII, only took half a century.

I propose we catch all the illegal boarder crossing Mexicans in bear traps and ship them in unpressurized cargo aircraft to the Vatican. We can pay for this through the seizure and auction of church assets. Then everyone can be happy.

How Fast? (4, Interesting)

th1ckasabr1ck (752151) | more than 9 years ago | (#11750760)

Anybody know how fast you would have to be going (theoretically or otherwise) before the Doppler Effect makes the signal unusable?

Re:How Fast? (0)

Anonymous Coward | more than 9 years ago | (#11750789)

I'm pretty sure 3.0 x 10^8 m/s would be too fast.

Re:How Fast? (5, Funny)

k4_pacific (736911) | more than 9 years ago | (#11750810)

Fast enough that you'd be out of range of the access point before you could find out if it worked or not.

Officer: Are you aware that you were going 0.90c in a 55 mph zone?

Driver: Ummm... I was?

Officer: Didn't you notice the blue shift son?

Re:How Fast? (4, Funny)

temojen (678985) | more than 9 years ago | (#11750887)

Driver: All I saw was the green lights of your roadblock.

Re:How Fast? (3, Funny)

X0563511 (793323) | more than 9 years ago | (#11750990)

The lights were off! You sure that wasn't the themal coming off of our radiators?

Steven Wright (1)

G27 Radio (78394) | more than 9 years ago | (#11750979)

Officer: I just clocked you driving 70mph. This is a 35mph zone.

Steve: I know, but I didn't intend to be out that long.

Re:Steven Wright (1)

k4_pacific (736911) | more than 9 years ago | (#11751177)

Actually, a friend of mine who was caught speeding told the cop he wanted to get home before he ran out of gas.

Re:How Fast? (2, Funny)

renehollan (138013) | more than 9 years ago | (#11751676)

I once remarked to a former boss about a red sign that said, "If this appears blue, you have exceeded the speed limit."

He didn't get the joke.

I quit that job and got a different one as fast as practical.

Re:How Fast? (0)

Anonymous Coward | more than 9 years ago | (#11750832)

Speed of light (Seriously)

Re:How Fast? (0)

Anonymous Coward | more than 9 years ago | (#11750986)

Speed of light (Seriously)

If you really want to be serious. . .

You don't have to go that fast. A few percent of the speed of light would shift 2.4 GHz right out of it's band.

Re:How Fast? (1)

Hadriel (856265) | more than 9 years ago | (#11750856)

Depends on the frequency sensativity of the antenna/reciever circuit. If the frequency cuttoff is relatively shallow then you should be able to go pretty quick, but as it appears to be designed mainly for cars then doppler shouldn't really be a prob.

Re:How Fast? (0)

Anonymous Coward | more than 9 years ago | (#11750878)

IIRC, doppler effects do not apply to EM waves. You do have blue shift and red shift, but that's a bit different.

Re:How Fast? (0)

Anonymous Coward | more than 9 years ago | (#11750970)

IIRC, doppler effects do not apply to EM waves. You do have blue shift and red shift, but that's a bit different.

No, it's all the same thing, except doppler is sound and red/blue are EM waves. All waves that propagate (redundant?) are affected by relative movements of the transmitter and receivers.

Re:How Fast? (1)

OrangeTide (124937) | more than 9 years ago | (#11750988)

Light is an "EM wave". A phonton is a messager particle for electromagnetic force. Visible light is very high frequency compared to radio transmissions like cellphones. But it's just a different energy level. You can look at this chart [lbl.gov] for more info.

Re:How Fast? (1)

John Courtland (585609) | more than 9 years ago | (#11751045)

That was me before (the AC, different machine). From what I remember, if you were on a "vehicle" travelling c, and you threw a baseball from the rear of the vehicle (exactly opposite the direction of travel), the EM waves emitting from the baseball will not change speed, defying any type of doppler effect. Perhaps I read that wrong all those years ago, but that's what I remember.

Re:How Fast? (1)

John Courtland (585609) | more than 9 years ago | (#11751144)

Well, looks like I'm none too smart, just looked it up. I wonder where I read that thing about the baseball though, I don't think that shit just appeared in my head. Son of a bitch.

Re:How Fast? (1)

eobanb (823187) | more than 9 years ago | (#11750908)

What might actually happen if this really occurred would be a shift in frequency, which in itself could easily be overcome by software radio. But anyway, you'd have to be going thousands of miles per second. Consider that colour is really just the differences in visible light frequency because of Doppler. The world in front of you would be turning red, and the world behind you turning blue, before you'd probably notice any problem in your connection. Even then, the TCP overhead would probably just grow. No, the real problem with this stuff is implementing real mesh-networking. For stuff like web browsing, jumping between different APs could actually work, since with the right sort of browser you could load some of the page from one connection, and the rest of the page, from a different connection, possibly with a different IP address, network interface, whatever. There is no way that that would work for something as real-time as VoIP. Wi-Fi is just not suited for this kind of thing.

Re:How Fast? (1)

X0563511 (793323) | more than 9 years ago | (#11751042)

You mixed up your red/blue shifts.

Moving quickly towards a transmitter will cause the wavelength to be shorter from your perspective, and the waves behind you longer, as they "lag" behind.

At 0.9c, thermal and some higher freq radio (like microwaves) would probably appear to you as light, while normal light would be shoved up past your perceptions.

Would certainly be an awsome experience, as looking behind, you could "see" UV, maybe X-Rays, ect.

Re:How Fast? (5, Informative)

DustMagnet (453493) | more than 9 years ago | (#11750942)

Light moves a lot faster than sound, so the amount of frequency shift is very small. A 2.4 GHz carrier would be shifted to 2.40000029 [google.com] at 80 MPH.

The frequencies of radios aren't very exact, so the tuners are designed to deal with some variation. Without knowing exactly how the tuners are designed (especially the filters), I can't answer your question, except to say, a whole lot faster than 80 MPH.

Re:How Fast? (1)

swight1701 (257154) | more than 9 years ago | (#11752056)

Doesn't relativity state that light is constant speed for every observer? The speed of light is always the speed of light no matter of direction or speed? How does a doppler effect work with radio waves then?

Re:How Fast? (2, Funny)

auburnate (755235) | more than 9 years ago | (#11751267)

Anybody know how fast you would have to be going (theoretically or otherwise) before the Doppler Effect makes the signal unusable?

No need to worry. Simply drive in reverse and it cancels the Doppler Effct.

Re:How Fast? (1)

EmbeddedJanitor (597831) | more than 9 years ago | (#11751344)

The channels are normally spaced at around 8kHz or so for voice, but channels for IP will likely be far wider. Most RF front-ends are going to use some sort of AFC since that's wy more reliable and cheaper than dicking around with temperature controlled crystal oscillators etc. THis would mean you'd need a hell of a big doppler shift to make any detectable problems.

Let's see. Supersonic aircraft still manage fine shifting digital data. So too do satellites and shuttles etc. Basically any car speeds are not going to register.

Re:How Fast? (1, Informative)

Anonymous Coward | more than 9 years ago | (#11751437)

When going over the doppler effect in my second semester of Physics, I asked the prof why our radios don't get distorted by the doppler effect when we are driving. He swiftly made me look like an ass by doing what I should have done instead of thinking out loud: plugged the numbers into the equation. As such, the equation. [thinkquest.org]

Well after signal strengh abates (2, Interesting)

bill_mcgonigle (4333) | more than 9 years ago | (#11751543)

I recently took a 10-hour Amtrak ride and picked up > 300 access points along the way. I could never keep signal to an access point for long enough to get a DHCP lease, much less see any doppler shift.

If everybody had a nice high-gain antenna on their roofs this would seem practical, but the little linksys dipoles aren't meant for and don't cut it for MAN'ing.

FP (-1, Offtopic)

Anonymous Coward | more than 9 years ago | (#11750764)

FP! HAHAHAH YOU SUCK!

I WIN. YOU LOSE!

aslkfdj zxcjv asdf asczvas sdf asv zxc vz xcvsa fa sdf zcxv zx cvda rd eaqea

Re:FP (0)

Anonymous Coward | more than 9 years ago | (#11751151)

Actually, no. You loose.

I loose too, for responding to you.

No go sulk in the corner and/or stare at goatse.

Public safety? (5, Interesting)

Anonymous Coward | more than 9 years ago | (#11750775)

How safe is using WiFi for such critical communication? Any kid with the right hardware can interfere with the WiFi signal. Not only that, but WiFi network congestion already creates problems for some people.

I don't know what the rage over VoIP is -- the telephone system has worked for many, many years. We're just opening ourselves up for another avenue of attack. Can anyone say terrorists with WiFi blockers?

Re:Public safety? (4, Funny)

k4_pacific (736911) | more than 9 years ago | (#11750835)

Well, I'm sure police radios can be jammed too. As for traditional telephones, efforts to install land lines in the cruisers have proven unsuccessful.

Any kid with a crystal radio kit (0)

Anonymous Coward | more than 9 years ago | (#11750901)

or a telephone can already interfere with emergency services. Trust me when I say, the mechanisms are already in place.

Re:Public safety? (1, Funny)

pclminion (145572) | more than 9 years ago | (#11751119)

Obviously the proper solution is for the emergency vehicles to drag a ten-mile strand of Cat5 behind them. Just imagine it -- an ambulance hurtling down the freeway with a blue network cable trailing behind, and a giant spool of Cat5 unreeling at 600 RPM... Tht tht tht tht tht tht tht

Redundancy (3, Insightful)

div_2n (525075) | more than 9 years ago | (#11751705)

The more modes of communication that law enforcements have available the better. I don't see why you would think that having one more is a bad thing. Remember that during 9/11 and the recent hurricanes that it was ham radio operators that did most of the communicating.

eh (2, Interesting)

eobanb (823187) | more than 9 years ago | (#11750791)

I dont know, I think this [apple.com] is 1337-er :)

Re:eh (0)

Anonymous Coward | more than 9 years ago | (#11751259)

you mis spelled g3hy-er

In other news... (2, Informative)

fireman sam (662213) | more than 9 years ago | (#11750802)

Cars have radios.

In the harbour tunnel in Sydney traffic reports are broadcast to most frequencies in the FM scale so people listening to the radio will here them.

Mind you it would be cool to have a VoIP broadcaster in the car so you can tell that jerk doing 20 under the speed limit to get the hell out of the overtaking lane.

Re:In other news... (2, Funny)

Anonymous Coward | more than 9 years ago | (#11750842)

Mind you it would be cool to have a VoIP broadcaster in the car so you can tell that jerk doing 20 under the speed limit to get the hell out of the overtaking lane

You can do this already with the mobile phone numbers on the side of tradesmen's vans.

"Is that Jake the plumber?"
"Yeah."
"Then stop driving like a twat."

They love it.

Good News for Motorists (5, Funny)

ackthpt (218170) | more than 9 years ago | (#11750815)

When the guy in the Luxus blasted past me at about 100 mph while blathering away on his cell call "hey fred, you should see how this thing handles on the shoulder of the road at 100 mph while one handed driving, marvelous..." he knew he could count on that keeping up with him. granted he was going substantially slower than the c (the speed of light).

Now he's assured that he could steer with his knees and type away on his laptop while driving similarly "hey fred, how to you spell 'psychopath'?"

Re:Good News for Motorists (1)

avalys (221114) | more than 9 years ago | (#11751639)

A Lexus, handling? Bah.

Maybe a BMW or a Jaguar or an Infiniti. But not a Lexus.

Netbacks? (4, Funny)

Tackhead (54550) | more than 9 years ago | (#11750818)

> have tested mobile VOIP over Wi-Fi at over 130 Km/h over an 8km stretch of Interstate highway somewhere near the Mexican border. Gee... I wonder what this is for?

"DEY TUK R CONTENT!"
- RIAA chair Cary Sherman

"Goddamn netbacks!"
- MPAA chair Jack Valenti

"I! LOVE! THIS! COMPANY!"
- Steve Ballmer, doing things you thought you could never get Americans to do for any price.

Whiskey Tango Foxtrot? (0)

Anonymous Coward | more than 9 years ago | (#11750819)

So is this for border control or to provide hotspots for our immigrating Mexican neighbors as they enter into the southwestern states?

BTW, there's an Ariozna posse [yahoo.com] forming to patrol the border.

oh please! (2, Insightful)

Jailbrekr (73837) | more than 9 years ago | (#11750843)

I predict that in a week, we'll be seeing articles about how they are stuffing mobile VoIP systems into pizza boxes with neon lights illuminating the insides.

OH COME ON. Report things which are relevant and unique, not 'omg its a wireless link that works at 80mph!'. Cel service works at speeds far faster than that (just ask anyone who used a cel phone on a plane before the ban).

Re:oh please! (0)

Anonymous Coward | more than 9 years ago | (#11751058)

OH COME ON. Report things which are relevant and unique, not 'omg its a wireless link that works at 80mph!'. Cel service works at speeds far faster than that (just ask anyone who used a cel phone on a plane before the ban).

The problem is hand off. WiFi wasn't designed for you to move from AP to AP. Cells were designed for it.

BTW, airplanes is a dumb example, since you can see the same tower for far longer than you can in a car.

Consumer access points: Speed of Roaming ? (-1, Offtopic)

Anonymous Coward | more than 9 years ago | (#11750882)

Hi,
a question for the experts.
Can you have an in-building WLAN with many access point and use a wi-fi VOIP phone, for example the hitachi WIP-5000
http://www.abptech.com/mainpages/product s/HCL-Wire lessIP5000.html

and walk through the building without get too long interruptions ? (ideal would be 1sec when roaming).

Assume all APs are on the same subnet, so the client keeps his IP while roaming.

Does consumer / enterprise class APs make a difference , or does it depend more from the client ?
For example I tried two different brands of pocket PCs with a softphone and one brand roamed really bad (call dropped, took long to find associate to the new AP), while the other was more acceptable (a couple of secs dropout).
The APs were two consumer APs (d-link).
Tried the same with an XP laptop running xten and the roaming dropout was barely noticeable.

Any direct experiences with VOIP over wi-fi roaming ?

thanks,
Mark

Re:Consumer access points: Speed of Roaming ? (1)

crabpeople (720852) | more than 9 years ago | (#11751310)

Well i can tell you from experience that we had about 8 machines try and connect over a wireless link and all run IP telephones. This was VoIP.

The router, an orinoco, crashed and burned after about 5 minutes. this is of course with users trying to do web traffic as well.

Seems to be whenever the wireless loses signal (happens ALOT) the voip call is dropped imidiately.

so yeah

Folks are doign it at 30k feet too (3, Interesting)

winkydink (650484) | more than 9 years ago | (#11750890)

Many frequent flyers have reported good results using Lufthansa's wireless internet in the sky with Skype. By contrast, doign this on a highway just seems a little humdrum.

Re:Folks are doign it at 30k feet too (1)

ackthpt (218170) | more than 9 years ago | (#11751028)

Many frequent flyers have reported good results using Lufthansa's wireless internet in the sky with Skype. By contrast, doign this on a highway just seems a little humdrum.

Isn't the signal actually relayed to/from the jet?

Re:Folks are doign it at 30k feet too (1)

Peyna (14792) | more than 9 years ago | (#11752146)

A lot less in the way of the signal when you're in the sky.

High Speed conversations (1)

06metzp (713177) | more than 9 years ago | (#11750894)

Now we know it's safe to use VoIP on the Autobahn. Of course by 'safe' I mean there'll be no signal loss...

wargames (3, Funny)

lokalhost (666083) | more than 9 years ago | (#11750898)

So how long before the wifi network gets a counterstrike server?

Mmmmmm! (-1, Flamebait)

Anonymous Coward | more than 9 years ago | (#11750925)

Hey, maybe drug dealers and smugglers can use it, too! Wouldn't that be funny, Narcs and druggies communicating over the same lines!

It sounds faster...measurement units (1)

Nom du Keyboard (633989) | more than 9 years ago | (#11750940)

It sounds faster when given in kph (Thousand P's per Hour).

YASUOM (4, Funny)

DoubleD (29726) | more than 9 years ago | (#11750967)

Yet another stupid unit of measure "almost faster than a speeding bullet."

Also what the heck kind of slow lazy bullets are almost slower than 80mph.

because I was curious I checked out the speed of a bullet. referencing this link:
http://hypertextbook.com/facts/1999/MariaPereyra.s html [hypertextbook.com]
puts the lower end of bullet speed at about 750mph and the upper end at 6700mph.

At least "almost as fast as a carrier pigeon in a tornado" would have been more accurate.

Re:YASUOM (1)

hexdcml (553714) | more than 9 years ago | (#11751312)

is that an African pigeon or European one?

Re:YASUOM (1)

RollingThunder (88952) | more than 9 years ago | (#11751459)

Shoot it down with a speeding bullet, and we should be able to tell upon closer inspection.

Re:YASUOM (3, Funny)

Peyna (14792) | more than 9 years ago | (#11752134)

I tried "1 speeding bullet to mph" on Google, but it wasn't able to do the conversion. They really need to update that.

Needs DeLorean compatibility (3, Funny)

istewart (463887) | more than 9 years ago | (#11751032)

Make it work at 88 miles per hour and then they'll be on to something.

Who are you and what have you done with Slashdot? (2, Funny)

StikyPad (445176) | more than 9 years ago | (#11751082)

No need to guess: according to the MuniWireless link, "the network is for public safety personnel (police, fire, ambulance and border patrol) first, with various community agencies, schools, business and local residents being added as the deployment expands beyond its targeted coverage areas."

Okay, what sort of alternate universe is this? This is the second story today where the submitter hasn't RTFA, but now this? Now the EDITOR actually read the story.

Is anyone else feeling just a little freaked out right about now?

Re:Who are you and what have you done with Slashdo (2, Funny)

Peyna (14792) | more than 9 years ago | (#11752126)

Not only that, but the editor that RTFA was TIMOTHY of all people.

I've already duct tapes all windows and doors in my apartment.

80mph in Mexico (1, Informative)

Anonymous Coward | more than 9 years ago | (#11751124)

VOIP over Wi-Fi at over 130 Km/h over an 8km stretch of Interstate highway somewhere near the Mexican border.

Gee... I wonder what this is for?

I could've used that last week... was visiting family in Mexico, and the border is a no-man's-land of U.S. and Mexican cellular zones fighting it out. At times I haven't been able to make cell calls 1 mile inside the U.S. because stupid TelMex signals were overpowering the weak AT&T signal down there.

Plus the 80mph thing is not so outrageous. My SUV speedometer shows 110mph max. Let's just say that the manufacturer apparently didn't cheat me... (thanks to those nice, long, straight, lightly-policed freeways Mexico has built recently.)

Re:80mph in Mexico (1)

cayce (189143) | more than 9 years ago | (#11751246)

"TelMex" is not a cellular company. It is a telephone/internet/long distance/frame relay company. You would be probably getting signal from TelCel, Telefonica or Pegaso, plus the fault wouldn't be from any of those companies but from AT&T for providing such a low signals at that zone. Basically at the US/Mexico border, the company that provides stronger signal owns the area.

I used to live at the border (about 5km inside mexico) and I was still able to put calls thru Nextel and I could use my Telcel phone as far as 20 km inside the US.

There's not a very good legislation regarding who owns what frequencies at the border. It looks like the FCC (USA authority) and the COFETEL (Mexico authority) don't talk to each other that much.

legality (0)

Anonymous Coward | more than 9 years ago | (#11751370)

is it legal to use a cellphone on a network thats outside the country?

remember when you use a cellphone you are TRANSMITTING as well as receiving.

when you use a network in your contry you have permission from the network who in turn have permission/license from the contries radio regulator (the FCC in the us case)

but when your on a foreign network you do not have permission from your contries regulator either directly or indirectly.

Any school bus (1)

jd (1658) | more than 9 years ago | (#11751172)

that travels at 130 Km/hour (81 miles per hour) has definite problems, besides that of the kids needing better connectivity for their World of Warcraft sessions.

Re:Any school bus (0)

Anonymous Coward | more than 9 years ago | (#11751314)

If you're travelling at 130 kelvin*meter/hour, you have DEFINITE problems.

Offtopic, but funny. (1)

thebes (663586) | more than 9 years ago | (#11751497)

Being an engineering student and having professors hound you for correct units, it IS fun to analyze how people abbreviate things and see what it is that they are really saying, according to the common use of particular abbreviations.

What about bluetooth VoIP? (1)

ktorn (586456) | more than 9 years ago | (#11751302)

The current problem with WiFi VoIP is that you need a really big handset.

What I really wanted was to use my mobile phone and make VoIP calls over bluetooth. Yes, the bluetooth range sucks, but at least it's a technology ready to use by my mobile. All it needs is an app (say J2ME) that handles the VoIP at the client side.

- or -

rather than use the mobile phone, use a bluetooth headset and link it straight to the bluetooth AP. The problem then being headset configuration and call making/receiving. Perhaps the mobile phone could act as a bluetooth remote control, or another alternative is to use something like this [jabra.com] and have it link up directly to the bluetooth AP, which then runs some kind of mobile phone emulator on the server-side.

I blogged about this before but only got a limited response (one guy who liked the idea, and that was it).

Is it feasible? Is anyone trying or willing to give it a try?

Re:What about bluetooth VoIP? (0)

Anonymous Coward | more than 9 years ago | (#11752107)

I do bluetooth voip all the time. Bluetooth link from headset to laptop, bluetooth link from laptop to cell phone for internet, cisco (or other voip software) at any freeway speed. It works very well. I have even used it to watch live tv over ip. (Not while driving of course.)

Re:What about bluetooth VoIP? (0)

Anonymous Coward | more than 9 years ago | (#11752173)

Bluetooth is intended to be used over short ranges, i.e. a cable replacement. It's great for syncing your PDA, printing from your laptop, or connecting a headset to your phone.

IIRC, the maximum range for Bluetooth is intended to be around 10 meters. I've managed to stretch the connection from my Palm (with the SDIO Bluetooth card) to a USB dongle up to about 25 meters. Even if you were to double that, you'd still end up with miniature Bluetooth "cell towers" every 100 meters or so.

Telecom companies want bang for the buck. If they're going to install infrastructure, they want it to cover as much area as possible.

Don't get me wrong; Bluetooth is great (especially when your AP is within range of the conference room where your all-day, doesn't-pertain-to-you-but-attendance-is-mandatory meeting is being held), but it's not meant for use over long distances. Stick to Wi-Fi for that. ;^)

Imagine... (1)

SunPin (596554) | more than 9 years ago | (#11751319)

what this could do at _88_ mph with a 1.21 gigawatt spark?

Tickets? (1)

Primal_theory (859040) | more than 9 years ago | (#11751436)

Can you get pulled over for this? or is there no speed limit?

car troubles (1)

bird603568 (808629) | more than 9 years ago | (#11751506)

looks like my car is gonna have to break down there often

Immigration (1)

sexysasian (592552) | more than 9 years ago | (#11751562)

I think the reference was to La Migra, yes?

Raleigh Fading (4, Interesting)

renehollan (138013) | more than 9 years ago | (#11751650)

I remember implementing communications code for packet radio modems way back in th' day... circa 1989, at 1200-9600 b/s.

The big problem with mobile radio sysems (particularly in urban environments) is Raleigh Fading, otherwise known as "picket fencing" noise. What happens is that one receives the radio signal via multiple paths, reflected from buildings in the "urban jungle". Sometimes these signals interfere constructively, and sometimes destructively. When driving, in an urban environment, one tends to move from areas of constructive to destructive interferance and back again, on a surprisingly regular basis. The effect is called "Raleigh Fading", after the statistical distribution of constructive and destructive zones. On an analog voice radio channel, it sounds like someone running a stick past a picket fence, hence "picket fencing noise". Of course, in environments with less opportunities for radio signal reflections, the effect is less predictible, but it still happens.

Naturally, transmitting and receiving a checksummed packet while driving through one of the areas of destructive interferance is, well, a challenge. If the non-acknowlegement retransmission rate, and speed are just so, you'll never get a packet through.

There are two ways of dealing with this: spacial diversity antennas (multiple antennas separated at carefully computed distances so that one is always in an area of constructive interferance when the other is in an area of destructive interferance), and interleaved error correcting codes. The spacial diversity antennas work well at the higher VHF and greater frequencies, because the distance between individual antennas isn't all that great. However, at frequencies of around 150 Mhz and lower, the required distance between individual antennas is too great to allow for automobile mounting. So, one uses interleaved error correcting codes (generally Reed Solomon), and hopes that one travels between zones of constructive and destructive interferance "fast enough". Yes, there is a mimumum driving speed related to data rate, carrier frequency, and error correcting code and interleave chosen, below which the system would not work. One generally picks an error correcting code so that the minimum speed is low enough that it would be practical to stop in an area of constructive interferance.

As I recall, at least one rural police force in Quebec, Canada was outfitted with the equipment we produced. Needless to say, the fade rate was not a problem when "Enos" (well, Jean-Guy in the Quebecois version of "Dukes of Hazzard") was in in "hot pursuit".

No, we did not interface the modem to the cruise control to ensure the vehicle was moving "fast enough", though it was damn tempting...

Of course, at modern data rates and carrier frequencies, spacial diversity antennas are a far better choice to combat this problem (and why wireless data network interfaces usually have two antennas).

Because public officers are super-human! (2, Funny)

Locke2005 (849178) | more than 9 years ago | (#11751717)

Remember folks, it's illegal for you to talk on a cell phone while driving, but it is perfectly ok for cops to type on a terminal while driving 80mph!

Shouldn't the same rules apply to everyone?

Re:Because public officers are super-human! (1)

demmer (623592) | more than 9 years ago | (#11751932)

you sir are stupid. ever come across an ambulance with more than one passenger?

Metric!? (-1, Redundant)

Anonymous Coward | more than 9 years ago | (#11751851)

WI-VOD have tested mobile VOIP over Wi-Fi at over 130 Km/h over an 8km stretch of Interstate highway


WTF is with this metric bullshit. This was done in the United States not Europe.

In other news... (2, Insightful)

po8 (187055) | more than 9 years ago | (#11751901)

  • WiFi VoIP tested in cold weather.
  • WiFi VoIP tested for use during full moon.
  • WiFi VoIP: can it work for brunettes?

Seriously. What possible reason would WiFi VoIP work any differently at 80MPH than in the rest Earth reference frame?

P.S. Before you say "Doppler Shift", go do the math and examine the chip specs. We have: we hope to shortly demonstrate 802.11b at Mach 2 [pdx.edu] .

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