[Vibrant General] BruceElliott:
[EDIT]

Some posters have responded that the assumptions made below are unrealistic as regards the average subscriber. That is absolutely true! This OP is unrelated to the "average subscriber." The thread is about the disconnect between the data download volume required by high-bandwidth apps being advertised by the carriers and the cummulative monthly data volume permitted by the carriers. I.e., this post would be valid if there were zero subscribers using these services. I would note, however, that these ideas will become increasingly applicable to the average subscriber as subscribers begin to use the cited services in greater volumes.

Other posters have commented that the 2 mbps assumption in this OP is unrealistically high. Please see posts 52, 54, and 75 for calculations related to actual apps that use similar bandwidths.

There has been much contraversy surrounding TMO's throttling network access speeds after a subscriber uses (or downloads?) 5 GB of data. Also, some people seem to be confused as to the meaning of the associated terms "bandwidth," "download speed," "total monthly usage," etc. This post is simply an attempt to clarify these terms and to add perspective to the issue.

I will use an (imprecise) analogy to household electrical power usage. The quantity of electrical power (measured in kilowatts), consumed at any point in time depends upon the sum of the current draw of the appliances, fixtures, machinery, etc. operating at that point in time. (Although power = voltage multiplied by current, the power company keeps the voltage relatively constant.)

Wireless data downloads can be considered as analogous to electrical power consumption if we analogize maximum link speed (also referred to as bandwidth) to voltage and bit flow to current. The power company maintains a (relatively constant) voltage to enable us to pull a variable amount of current according to our needs. A carrier maintains a (variable) amount of bandwidth to enable us to transfer a variable amount of data according to our needs.

Kilowatts and bits/second are both instantaeous values. So, the electric meter must continuously meter the current as it flows through the meter to sum the total energy used (kilowatt-hours). Likewise, TMO (apparently) implements a meter on their servers for each subscriber to monitor data flow over the course of a billing month.

Now, this is where the analogy gets interesting. :D

The power company charges per usage while TMO advertises and charges a flat monthly rate (assuming an "unlimited" data plan). On the surface (read: "as advertised"), the TMO plan sounds better. One is able to plan for a fixed monthly expenditure without having to worry about consumption. That is very appealing, because TMO has also heavily marketed their newer and ever-faster networks as well as devices and services requiring these greater bandwidths.

But notice what happens when a customer attempts to aggressively use the new devices, services, and supporting network bandwidths. When the data throttling hammer comes down, Internet data services are simply terminated until the beginning of the next billing month, for most practical purposes! (The modern Internet is largely non-functional at 56 kb.)

How would such behaviour play out with household energy consumption per our analogy? Say the power company initiates a big marketing campaign to place equipment and services in your home that require lots of power to operate, and sets you up on a flat monthly fee. To accommodate the new equipment and services, the power company drops 10kV service to your home. The first month, You use the new, very power-hungry equipment and services for 5-6 hours. By then, you have used 20,000 kwH. The power company's policy is to throttle users who reach 20,000 kwH. So what do they do? According to the analogy, they decrease the voltage to your house to 20 volts. Of course, 20 volts is not enough to run anything except perhaps enough to make a couple of light bulbs flicker. However, the power company can say that, technically, they have not breached their obligation to supply you unlimited power for a fixed fee. If you can do something with 20 volts for the remainder of the billing month, have at it!

For both the power company and a wireless carrier, these are peak loading problems. The difference is that the power company builds out the infrastructure necessary to handle peak loading for all of its customers, big and small.

A wireless data carrier can "build out" in two dimensions, speed and capacity. These are related but different quantities. Say TMO replaces transceiver technology on a tower. Say the old system had 4 transceivers, each capable of handling 1000 subscribers and providing data speeds of between 500kbps and 5 Mbps to each subscriber depending upon the number of data users connected to that tower. Now assume that the upgrade has five transceivers, each capable of handling 1000 subscribers. New technolgoy coding techniques now render a transceiver capable of providing data speeds of 1-21 Mbps, depending upon the number of data uses connected to that transceiver and their data requirements, etc. In this scenario, the carrier could do fancy marketing to pull in additional subscribers and some users would in fact sometimes see faster downloads. However, the carrier might not have accomplished much from a capacity standpoint in this scenario. E.g., tripling the number of 3G radios might be better from a capacity standpoint than replacing the existing 3G radios with 4G radios. However, the latter is much sexier from a marketing standpoint.

We will know when TMO has finally built out sufficient capacity to satisfy the data demand that they themselves create by hyping speed and speed-requiring services such as TMO-TV; because at that point there will be no further need for data caps and they will be removed or increased to higher thresholds. In the meantime, the following calculation is an indication of the amount of "unlimited" nework access we currently receive from TMO in exchange for our $80 - $100:

What is your average download speed? Of course it varies from region to region and from one moment to the next. Let us just pick some reasonable number as an average to work with, say 2 mbps. Consider that average and the 5 GB data cap. For quick calculation purposes, let us consider 10 bits/byte. (The real number is ~9 bits/byte after taking into account error correction overhead, etc.)

(5 x 10E9 Bytes) x (10 bits/byte) = 5 x 10E10 bits

(5 x 10E10 bits) / (2 x 10E6 bits/sec) = 25000 seconds

(25,000 seconds) / (3600 seconds/hr) = 6.9 hours

In conclusion:

An "unlimited" TMO data plan provides about 7 hours of [clarification: high bandwidth application] access monthly, based upon advertised and provided speeds, before one is cut off from useful data access. Your available number of hours will vary according to the data speeds that you experience/utilize.

There are ~720 hours in a month. Thus, our carrier's plan provides for 2 mbps use of our phone about 1% of the time or about 25 minutes per day. :eek:

If you understand and are happy with this (as many no doubt are), wonderful! I believe that a subscriber should at least be aware of what he/she is getting for his/her $80-$100 per month, though; and the carriers should, but do not, disclose this information.