Is Throttling Smartphones Pointless? Study Suggests So
bits.blogs.nytimes.com
bits.blogs.nytimes.com
TL;DR version the 'unlimited guys' use the same total bandwidth as the 'limited' guys.
This is extreme proofiness[1]. You notice that the 'average' is much higher in unmetered plans while the median is the same? If you know your maths you will recognize that data hogs hog a lot which results in a higher average. AT&Ts throttling on the other hand keeps the 'median' about the same.
The real issue for the carriers is that they have a fixed amount of bandwidth within their system which is difficult (read expensive) to increase.
Network bandwidth is one of those commodities that exists all the time, whether or not it is being used.
People don't predictably use the bandwidth so its hard to sell "all" of it for money.
So you end up with bandwidth that is sitting there unused and losing money (it has a constant cost of ownership which is an amortization of maintenance, depreciation, and licensing fees)
Their solution was to offer an 'unlimited' plan which, for an extra fee, lets folks go over the max tiered plan. This allows them to 'sell' bandwidth that might have otherwise gone unused. But if they drive the total use over their hard stop EVERYONE runs out of juice.
So their 'fix' is that if you're pushing the average up they clip your usage. That keeps the median in line with their highest rate plan while allowing them to sell the excess bandwidth they have for those cases when everyone asks at once for it.
[1] http://www.amazon.com/Proofiness-Youre-Fooled-Numbers-ebook/...
See e.g. http://www.cwta.ca/CWTASite/english/pdf/Ovum_SpectrumFees.pd...
The discussion is pointless either way, because actual speech takes up a lot more of that precious air time and only costs marginally more. You could literally send a complete book over the air disguised as "speech" and pay a miniscule fraction of what it would cost you to divide it up into tiny 160 byte blocks.
Which then gets us back to antitrust.
In GSM, something like the following happens:
1) User submits SMS to their mobile phone.
2) Phone starts paging on a random access channel (no synchronization, lots of phones trying to talk at the same time - limited resources for phones to transmit, and limited chance for base station to receive an intact message). Increased load on these channels require operator to have increased capacity, and thus increased spectrum, increased hardware to handle peak throughput (even if network is idle most of the time - one reason prices may not drop as the network's popularity increases)
3) Base station manages to hear an intact access request, allocates a dedicates timeslot on a control channel (a timeslice of spectrum dedicated entirely to one particular handset - the number of available slices in a given area is more likely measured in the 10s, not the 100s), uses yet more spectrum to inform phone of allocation.
4) Phone indicates desire via dedicated control channel to start SMS transaction.
[half a second of allocated time on a licensed band elapses]
5) Phone transmits message.
6) Phone retransmits message due to poor network visibility.
7) Network signals SMS received, closes transaction.
[resources used within network to route, store and forward message, payment made to peering network to which the target phone is connected to]
8) Remote network begins paging target handset on a camping timeslot it shares with a bunch of other phones, on frequencies covered by a second billion dollar spectrum license.
9) Remote phone wakes up, begins placing load on random access channel.
[lots of retries and corrupting of other users' random access requests later]
10) Remote network allocates control timeslot, and begins attempting to inform target phone of its allocation.
[another few second of allocated spectrum go here]
I spent two years working on carrier software for this section of the SMS transmission procedure and there are plenty of things here which cost the carriers money. SMS is definitely not free to the carrier.
Also, from my understanding, they don't actually piggy-back on the control messages, at least not after they have entered the wired part of the system (I never worked in the over-the-air part of the system, so have no knowledge of what happens there). That is, even if the control messages were sent constantly, SMS messages don't get a free ride, but rather they share the bandwidth with the control messages, since those messages do not require near as much bandwidth as the voice channels do.
As an aside, one carrier we installed our system in could only handle a thousand or two messages per second tops, after that, messages were dropped (well, TCAP transactions meant they were re-transmitted later), so there isn't some magical unlimited bandwidth available to SMS messages.
Thats a cool and complex protocol, but prices have nothing to do with that.
When I worked in telecoms a couple of years ago, we installed our SMS anti spam/fraud system in a network where a disproportionate amount of SMS traffic was caused by a virus on handsets that was constantly sending SMS messages. This was costing the carrier enough money that they installed our expensive anti spam system.
So all the tower and network construction and maintenance is free? I see this 'it cost nothing' all the time, but it's really a dishonest way to look at the cost of text by putting the entire infrastructure cost on voice.
What you're saying -- which is that data hogs push the unlimited average much higher than the limited average -- is not actually what is happening. AT&T doesn't have to try to match the medium data useage (although that is indeed what is happening). I think what you should be saying is that AT&Ts throttling keeps both the medium and the mean about the same. This is because people on the unlimited plans don't necessarily use more data than the tiered people.
If you look at the actual data (which, unfortunately wasn't in the NYT article) the top 5% of data users across all plans and carriers is about 3.7GB. This is already below the 5GB cap. I think what the article posits makes sense. The purpose of throttling unlimited users who are already below the 5GB cap is to get grandfathered people off unlimited. It's a rotten deal because they (and by "they", I mean mostly AT&T) want to make their unlimited plans undesirable so that you never use much more than 5GB, which is the cap for the tiered plan anyway. Sure, you get theoretically higher monthly bandwidth but the quality of service is actually worse than the tiered plans.
And that is food for thought when your provider is giving you 5GB or otherwise limited plans _for a whole month_ while marketing phones with transfer rates well above (or on par) with most home connections.
In this case, the observed effects of throttling are: - customers paying more money for overages - customers with grandfathered unlimited plans sticking around even if they might be better off elsewhere - customers reducing usage - customers paying more for higher limits - customers at the right edge of the graph looking elsewhere
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