Cell in a Handbasket

Jeff Taylor | December 10, 2004

As this confusing story conveys, the use of cell phones on airplanes is not the safety no-no we've all been led to believe it is. We're talking aircraft that fly through lightning storms, so a few more waves of energy need not send the craft corkscrewing into the ground.

The ban on airplane cell use has always been more about keeping the cell system working properly than safety. The genius of the cell system is that each cell "hands off" calls to other cells as the caller moves around. When you make a cell call from the ground you basically hit one cell tower, then another, then another in serial fashion. But get up in the air and make a call and you might light up all the cells in, say, Denver. Hundreds or thousands of people doing that in flight could choke the system down, no one really knows.

But with the airlines struggling for any revenue source there is great promise in charging passengers a fee for some sort of access code to the plane's "cell router." These are the guys that charged $5 to rent crappy headphones so anything is possible.

Comments

|12.10.04 @ 10:05AM|#

These are the guys that charged $5 to rent crappy headphones so anything is possible.

On JetBlue you get the crappy headphones for free.

Highway|12.10.04 @ 10:09AM|#

On Southwest there's nothing to listen to.

|12.10.04 @ 10:16AM|#

Heh. I had always wondered about the "safety" aspects of cellphone use.

|12.10.04 @ 10:17AM|#

on frontier its crappy cable TV... fork out another 7 bucks and get a day and half old wrap. yum. I can only imagine what the onboard roaming fees will be.

aix42|12.10.04 @ 10:25AM|#

"and you might light up all the cells in, say, Denver"

That would not happen. Handoffs/call set up utilize various algorithms to determine the best cell to hand off to [or set up on]. A mobile can see several cells at once, but can only 'talk' to one at a time. All 'cells' are 'lit up' all the time, broadcasting their own signal for the mobiles to read. Urban, downtown areas have a similar problem, with several cells appearing to the mobile as having the same signal strength. Even if all the various analysis cannot determine a prime candidate the system will just default to one.

|12.10.04 @ 10:30AM|#

The typical cell tower is directional, and its direction ain't up. It would seemingly have to be satellite-based.

But the handoff issue is a good one. Location updates (even when you're not in an active call) make up most of the signaling associated with wireless communication. Systems aren't made to support a mobile phone traveling at 500mph.

I just dread the prospect of sitting b/w two businessmen, or worse, two teenage girls, yapping non-stop on a 3 hour flight. I think free liquor would have to accompany this rule change.

|12.10.04 @ 10:38AM|#

Aix (last name Xerxes or do u just like IBM UNIX?) -

I don't think every cell system has that ability yet. Like you say it makes sense in dense urban areas, but other places, not so much. I just used denver cuz it is pancake flat to the east, maybe should've said omaha http://www.pbs.org/cringely/pulpit/pulpit20040715.html

|12.10.04 @ 10:47AM|#

Jeff,

I'm not familiar with every wireless technology, but AMPS/analog, TDMA, GSM, CDMA and UMTS have all supported the ability (different implementations, of course) to measure signal strengths from various target cells and attempt to handover to the strongest. Depending on the measure of cell overlap, hysteresis values, etc. the time you have to complete the handover would vary. Traveling at 500mph presents its own challenges, obviously.

Flat rural areas might have what used to be called "boomer cells" which had tremendous coverage areas, which obviously made handovers less frequent.

aix42|12.10.04 @ 11:01AM|#

actually AIX works out to Angstnine, 42 from Hichhikers Guide...

Anyway, as Akira states, all cell technologies use a system for hand offs, rural areas are easier due to the larger distances covered by omni cells [less handoffs]. The Antennas are tilted to provide max coverage to where we usually are, on the ground. We get complaints from high rises etc.... I would be surprised if a signal could make it up to cruising altitude.

|12.10.04 @ 12:29PM|#

Isn't it turning out that the "dangers" of cell phones in hospitals are also over-rated?

Not having worked on the relevant technologies I can't say for sure that it's over-rated, but as a physicist I can sort of look at the possible scenarios and rule out a lot of things. The circuits that process information (i.e. computers) are shielded by edict of the FCC. The biggest vulnerability would seem to be in the unshielded components, i.e. the probes carrying electrical signals from a patient to the computer. However, electrical activity in the brain and heart oscillates on time scales much longer than the period of a cell phone's carrier signal. So my first guess is that the signal from a cell phone wouldn't interfere with the signal from a patient's brain or heart.

Then again, there could be something that I'm overlooking. Can anybody help me out here?

|12.10.04 @ 12:34PM|#

Considering just how fucking annoying it is to listen to people yapping on their cell phones, I hope the airlines charge as much for cell access as they did for those seatback phones that nobody used.

Last Sunday I rode Amtrak. A group of people two seats in front of me were having a conversation and I couldn't hear a word they were saying. At the same time, a guy eight seats in front of me was talking on his cell phone and I could hear every single syllable clearly.

|12.10.04 @ 12:47PM|#

Larry,

http://www.coudal.com/Shhh.pdf

Enjoy.

|12.10.04 @ 1:08PM|#

Bah, who cares about celphones; its too loud to talk on a plane anyway. What I want to know is when more airlines are going to start adding complimentary internet connections.

|12.10.04 @ 2:17PM|#

Wait a minute, is Jeff calling my beloved Denver flyover country?

And the only thing worse than having someone yapping on a cellphone next to me on an airplane is having that someone yapping at me on an airplane.

|12.10.04 @ 2:21PM|#

But the rule sure does prevent a lot of inconsiderate assholes who think its OK to make phone calls in confined public spaces from getting punched in the face.

Highway|12.10.04 @ 2:22PM|#

thoreau,

The 'dangers' of cell phones in hospitals have always been overrated. Everyone who works in a hospital uses a cell phone there. If you tried to tell surgeons to turn theirs off, they'd laugh long and hard, and then go get pissed at your supervisor. I'd imagine that the rules are mostly holdovers from early days of cell phones, when they used much lower frequencies, emitted lots more power, and were much bigger unknowns. They probably didn't want to run any risks of having the equipment affected by variables like that. Now, I think the rules are mostly a way to keep yappy people off the nurse's floor.

Phil|12.10.04 @ 3:13PM|#

Last Sunday I rode Amtrak. A group of people two seats in front of me were having a conversation and I couldn't hear a word they were saying. At the same time, a guy eight seats in front of me was talking on his cell phone and I could hear every single syllable clearly.

A couple months ago on an Amtrak trip from NY to DC, I got a guy in my car who spent about half an hour talking at the very top of his lungs on his cellphone with his wife . . . and he had his wife on the frigging speakerphone. Unbelievable.

|12.10.04 @ 3:22PM|#

Aix,

Actually, I think an jetliner is a great place to get reception. You have pretty much line-of-sight to a bunch of towers at a distanace of 5-10 miles (depends on how close your towers are, obviously). And though you will get some attenuation from off-axis reception at the tower end, I'll bet the lack of interference along the way makes up for it.
Remember 9/11 - when other passengers on the planes figured out what was going on, out came the cell phones.

This should be fairly easy to test. Power output control is a big part of how CDMA works. You just need to get the phone to report it output power setting to see if it's "straining" to stay in touch.

Thoureau,

The FCC doesn't require shielding. It just limits the amount of RF power you can "leak". If you can stay witin the limit, you don't need to do anything in paticular.
In fact, I believe that medical devices MUST NOT be shielded for electrical isolation (safety) reasons. I would also assume that tolerating common RF signals is part of the certification process, but I don't know the deatils.

To all commenting on the 'annoyances' of public cell phone use,

Why is this worse than two strangers having a conversation within earshot? Why is it worse than a stranger trying to strike up a conversation with you?

|12.10.04 @ 4:58PM|#

tchiers-

Thanks for the clarification on shielding.

I can see why a ban on cell phones in hospitals might have made sense when it was an unknown. But I can't think of any technical scenario where a phone is likely to interfere with hospital equipment, and the responses on this thread confirm that.

|12.10.04 @ 5:13PM|#

I agree that a ban on cell phones in hospitals seems totally unnecessary.

And cellular base station designers need to design for 500 Mph handoff, because there's no good reason to forbid them on a plane, either.

Relaxed FCC rules on planes, plus 3G data services - that's REAL high speed internet.

|12.10.04 @ 5:32PM|#

I hear that cell phones eat thru batteries on fast trains in Europe like on the TGV here in France, since they're handing off so often.

Modern GSM and CDMA phones use soft handoff -- they actually transfer the call thru the second tower before breaking the connection with the first. But yes, they can keep track of a number at once, and they only actually "talk" with two for a very short period of time.

Larry A|12.10.04 @ 8:05PM|#

I kind of figured out that cell phones wouldn't make airplanes fall out of the sky when the Homeland Security folks started talking about issuing stun guns to the aircrews.

|12.11.04 @ 1:52PM|#

Sure, I believe that airlines prevent me from using my cell phone on the plane out of purely altruistic consideration for the poor phone companies down there on the ground.

Or could it be that they'd prefer me to use their overpriced plane phones ? Nah. Can't be.

|12.11.04 @ 11:29PM|#

Anybody know why one can't listen to CD players on airplaines? I've lied about a thousand times and told attendents that I'm listening to the radio (I have one of those wierd old discmans with an am/fm radio built in) but I can't see how the laser from the CD player is dangerous to the flight. Maybe one could rig it so it could be used to blind the pilot, but... wait, no one could do that.

|12.11.04 @ 11:30PM|#

i before e except after c, and in the word weird

|12.13.04 @ 11:02AM|#

Bocephus,
It's not the laser they are worried about, it's th internal electronics and clocks that also emit RF (any time a charge moves it is going to emit RF) that is the reason they want you to turn off CD players. I think it's all crap because every piece of equipment on an airplane that involves receiving RF signals would have a friggin FITLER on it so that it doesn't pick up cell phones/electronics emissions. It's all just folks being told something and then being all high and mighty with the info when they are in a position of power, even though they have no clue how any of it works or why they are telling you certain things.

|12.13.04 @ 12:58PM|#

To all commenting on the 'annoyances' of public cell phone use,

Why is this worse than two strangers having a conversation within earshot? Why is it worse than a stranger trying to strike up a conversation with you?

I THINK IT'S BECAUSE THE "VOLUME" OF THE PERSON CONVERSING ON A CELL PHONE TENDS TO BE A BIT LOUDER THAN SOMEONE HAVING A NORMAL CONVERSATION. THEREFORE, INSTEAD OF BEING "WHITE NOISE IN THE BACKGROUND," IT IS MORE INTRUSIVE.

LOUD TALKING IS ANNOYING.

|12.13.04 @ 1:01PM|#

Ask a pilot, folks. There are a number of cases where radios and other electronic devices interfered with flight operation. Google it.

Safety first, yakkers second.