Over the weekend I went on a camping trip with my brother, my fiance, and his sister. There were other people around, but as far as I know we were the only ones who encountered this problem, since I didn’t get the chance to ask anyone else about it. Brother and I have the same model phone, and my fiance and sister have different models, but we all use Verizon. (I think all the phones are “LG” as well.) We all charged our phones the night before we left, and we were camping pretty much in the middle of nowhere, just outside Florence, Arizona.
All our cellphones died over the weekend. Mine was one of the last to die. I had only tried to make one call on it, otherwise it was sitting in my purse the entire time, on. My brother used his a couple times, fiance and his sister used theirs pretty much not at all.
Anybody have any idea what happened to all our phones?
My phone does the same thing at Ren faire - since the site is so far away from anywhere, the phone is roaming and kicks up its transmit power to stay in contact with the nearest analog tower.
If I forget to turn it off, a phone freshly charged on Friday morning will be dead on Sunday night - if I stay near civilization, a charge usually lasts a week.
Heh, that’s true, but we had the cellphones in case of an emergency. It’s not like we were glued to them the entire time, they were just there if we needed them.
Depending on your make and model of phone you may find one of these useful. It is basically a wind-up mobile phone charger, it could be very useful if you go camping often and only costs about $10, a small price to pay for the piece of mind that should anything go wrong your phone will always have charge (though not necessarily signal).
I’ll expand a bit on what Gotpasswords was saying, and the way that cell phones work. In fact, this relates to the very reason they’re called “cell” phones.
Before cell phones, you had mobile phones. Basically, a city had a central tower and each phone needed enough power to talk with the tower from anywhere in the city. Also, you could only have a limited number of phones in a city, since everyone in the service area had to share a few frequencies.
Cell phones apply some slick technology to talk only with the closest tower. By adding more and more towers across an area, you create smaller and smaller cells and both tower and phone will automatically dial back the transmission power.
The main benefit, actually, isn’t really in power savings - it’s that you now have an unlimited number of users. By using only the transmission power needed to cover your local cell, the frequencies can be re-used inside each cell and not interfere with other cell’s use of the same frequency. Got more subscribers? Just add more towers to make the cells smaller!
But one of the complicating factors, among many, is knowing which cell every phone is in, so that the correct tower can ring the phone when it receives an incoming call. To this end, phones and towers are regularly talking back-and-forth behind your back. So long as the phone is powered-on, it will be occasionally signalling the tower - even if you’re not using it.
So in your case the distance to the nearest tower was such that these regular “I’m here.” signals from your phones to the tower had to be at high power, and just ran down the battery.
The only real solution is to turn the phone off or, if you are expecting an incoming call, get a portable recharger.
Good post except for this bit. The number of users a tower can support simultaneously is not related to cell size or frequency usage. It’s related instead to bandwidth and, to a lesser extent, the multiplexing scheme used. Cell phones on the same network all use the same frequency (actually, spread spectrum and similar technologies mean that the phones and towers “hop” from one frequency to another very rapidly, but we’ll disregard this here). Signals reaching the tower from multiple phones are combined using a process called multiplexing. One of the first multiplexing schemes was an analog method called TDMA, for Time Division Multiple Access, and was based on an older multiplexing technique used in landline telephone network backbones for putting hundreds of phone calls on a few pairs of wires. Basically, TDMA slices up each call into little segments, and puts segments from each call on the network, in turn, with a specific timing. At the other end, the individual call segments are pulled off at the precise times and reassembled back into their proper order. TDMA can only support a few hundred simultaneous users for each tower. Newer systems use a digital multiplexing scheme called CDMA, for Code Division Multiple Access. In this system, the calls are also sliced up into segments, but instead of using timing to multiplex and demultiplex, digital codes are used to identify which call segments go with which. The number of simultaneous users in such a system is limited only by bandwidth. CDMA is being largely supplanted by yet another technology called GSM, for Global System for Mobile (communications), but I won’t bore you with the details.
Ah, but you misunderstood a bit. At that point, I was not talking about how many phones a *tower * could support (for which question, your explanation is correct.)
I was instead talking about how many subscribers your *system * as a whole (say a city) could support. This is, indeed, a direct function of cell size. Even all of the mechanisms you mentioned could not support very many total users if you couldn’t sub-divide it into smaller-and-smaller cells as your subscriber base grew.
And, to make this work, it is a requirement that both towers and phones scale back their transmission power so as not to stomp on the signals in other cells.
Well, yes and no. You’re right that I misread that part of your post a bit, and that the total number of network users is related to cell size, but cell size alone is not the sole factor. Bandwidth, compression schemes and multiplexing techniques all contribute to the overall system usage, too. In fact, those are more important than cell size as far as the provider is concerned, because ultimately they all cost less to implement than building new towers. If you can pack more users onto a given tower with a newer technology like GSM, it’s generally more cost-effective to do so than to build more towers - which has problems like zoning issues, in addition to the costs of the physical equipment, which the other factors do not.
Not to take the discussion too far afield, Q.E.D., but I have to disagree with you:
But you’ll have to notice that ultimately they’re called “cell phones”, not “multiplexed phones” or “frequency-hopping phones.”
Cellular architecture is THE technology that moved mobile telephony out of the limousine and into everyone’s purse/belt pouch.
It doesn’t matter how much multiplexing you add to the system, if you still only had one tower for a whole city the number of available phones would only be enough to supply the top tier of corporate executives in the area. And if the cell towers were only repeaters to increase the coverage area, the situation would just be worse.
The telcos may spend more time on any given day thinking about new multiplexing technologies, but it’s sort of like the fish who doesn’t spend much time thinking about the ocean. The ability to sub-divide into new cells is still what breathes life into modern mobile telecommunications.
Not really. There are still practical limitations to how many towers can be built in a given area. The providers cannot just put a tower up wherever they feel like it. They have to get zoning permission from the local governement, and possibly the FAA and other entities as well. And, in point of fact, PCS and GSM systems aren’t even “true” cellular systems anymore. PCS phones, for example, try to connect to not one, but at least three different towers at the same time, which is supposed to reduce dropped calls by ensuring you alwys have an available connection. In this system, increasing the number of towers does less towards increasing the total system volume than compression or multiplexing schemes do.
Back to the OP, another issue is that most US phones now are dual band, analog & digital.
The analog mode burns a LOT more power, maybe 10x as much. But it has somewhat bettter range.
So as you drive / walk out into the sticks, eventually you get out of digital range & the phone switches to analog mode to keep contact. And you just changed from having battteries with 5 days of standby time to just 15 hours of standby time. Some phones beep when they switch, or have some little screen icon which means analog mode, but if you’re not looking for it you won’t recognize it.
I agree that this it the reason. My phone can go for hours on a digital signal, but on a analog signal can only talk 5 minutes before the battery strength drops too much and it shuts down. The phone will recover and I can make another call a bit later. THe analog just takes more power then the battery can supply at a given moment, even though it has sufficent energy.
When not in use the phone still ‘pings’ the tower and in analog mode uses much more power.
I know my phone can be forced to use analog (useful when you have a crappy digital signal), and I think some can be put into digital only mode.
You say “tried”. Did it actually work? If you had no service out where you were camping, that could explain the problem all by itself. When your phone is searching for service, it uses more battery power than when it has found service and knows exactly how much power it needs to transmit with. A lot of phones will shut off after searching for a certain amount of time, because searching all night runs down your battery.
There’s digital TDMA too. Before AT&T Wireless and Cingular (now the same company) offered GSM, they had digital TDMA. In fact, GSM is a TDMA system - it’s not compatible with the other one, but it divides each frequency into timeslices. I believe Nextel’s iDEN is also a TDMA system.
This is a feature of CDMA, not the frequency band (“PCS” refers to the 1900 MHz band, and “cellular” to the 800 MHz band, not that most people use the terms that way). It’s called “soft handoff”, and I wasn’t aware GSM had anything similar.
