All right, hello and welcome back. Today we're going to move on to a different principle. It's called Network Is Expensive. And so the main theme here is going to be that your cellular data providers like AT&t and Verizon charge you a lot for the data that you use. Or you may think that they charge you a lot. Really it makes quite a bit of sense, the reasons why they do charge you as much as they do. And so the, the question we're going to try to answer here is. Why do Verizon and AT&T charge you something like $10, first of all and second of all, for every gigabyte. So why is it per gigabyte? Why does it keep going up? The cost keep going up as you consume more gigabytes. And so that probably makes intuitive sense to you that it should go up every time you consume because if you're consuming more, you should have to pay more. But that wasn't the way it was a few years back and so we'll look at what prompted the change to payments like this. And we'll look at those things throughout this lecture. So before we look at our mobile data plan specifically. Let's take a look at our utility bills like our electric bill, water bill, or gas bill that you may have paid at one time or another. And we know that those are all based on the quantity that we consume, right. So if it's electricity, if you've every looked at your bill you pay certain amount dollars per kilowatt hour. And that's the unit for energy, we won't go into that specifically. But for every unit of energy you're consuming, or every unit of electrical energy here, you're going to pay a certain amount. And same thing for the water company, you're going to pay a certain amount, a certain number of dollars for every amount of water that you're using. And so, these are all based on quantity, so you, you always try to consume as little as you can, if, if you know, unless you need more then you can consume more. But you only use what you need is the bottom line. Because you don't want to have to pay more for something that you don't really need to use. And that's helps you save money and be able to do this efficiently, and so on. And so, basing it on quantity makes sense in that regard because you, if you are good and you don't want to. And you're not using as much electricity and you know how to conserve it. Or you're not using as much water and you know how to conserve it, then you're not going to have to pay as much. So, and that's good for not only you, but also for the network because it's not adding as much congestion. Or making the network have to transport too much energy to your home. And recently data plans have also been based on quantity. So, not only utility bills but now also our data plans are based on the quantity, specifically in dollars per gigabyte or something along those lines. And we'll look at again what a gigabyte means here as well. And so here on your iPhone, for instance. there are some apps that are available. Some free apps even. This one specifically is called Data Wiz. And that's something that was developed in our lab over the past few years, our lab at Princeton. And this will give you a maximum recommendation for how much you could, should consume each day. Based upon what your total allowance is in a given month from your data provider. And so the, here you can see that you've gone 6.1% of your 14.4 megabytes that they're offering you for the day. Or that they recommend that you consume for the day and you can check your consumption here as well. And people start to use a lot more as data plans have become based on quantity. Because they used to be you would just pay some certain amount at the beginning of the month and get your allocation and then you just. So, it used to be that you would just pay a certain amount each month and you could get your allocation. And then, or it could be, even be unlimited. Then you could just go and consume however much you want. And you would basically be free after that. And so. The question we're really going to be answering here, and it goes hand in hand with the first question we looked at is. Why are there no more unlimited data plans? So some of you may still have unlimited data plans so you can pay something like $40 a month and use as much data as you want. And never be charged another dime. And, the question is why aren't providers offering that anymore? AT&T and Verizon recently have decided not to do that, as well as providers in other countries as well. But they've decided not to offer any more unlimited data plans. And so the question we're going to ask is why did they switch? Why did they switch now and not offer unlimited any more? And it actually has a very good and logical answer as to why that they're not doing that. And we'll see that throughout this lecture.
