So, the MTS and the IMTS systems each had 32 channels and we're talking about frequency in channels here, and those were between 40 MHz and 460 MHz. So, a few points that we discussed before was that each channel needs some with the frequencies, which defines its channel width. So, if we look at, for instance, a channel, maybe over here, there would be 32 such channels between 40 and 460 MHZ. And they each, like as we said, they have some amount of space between them that they need. And we call this in here, the channel width,this is the width or however large it needs to be in order to transmit in that window. So, each of them has a finite width they need. They can't just be at a single frequency, they need some range of frequencies in order to operate most efficiently and most effectively. So, there were only 32 of these total, they are the MTS and the IMCS systems which means that at any given time you only have 32 channels to play with. So, you can only have 32 calls at any given time, so you can image that as people started hearing about the idea of mobile phone technology, and even if they were just car phones, then there were probably many more than 32 people who wanted to use the network. And eventually that caused the network to start bursting at the seams. So, operators needed to deal with this issue, to try to get more people to be able to talk on these phone systems. And so, the first option was to go to the FCC, the Federal Communications Commission. And the FCC was established in 1934 to oversee the development of communication technologies in the US. And one of the things that it does is it deals with licensing issues. So, you need a license to transmit in a cellular band. So, your operator, whoever your phone operator is, AT&T, Verizon, and so on, they need a license to be able to use that band of frequencies. And that license will come from the FCC when they apply for it. So now, the process of applying of the FCC for a license though is pretty grueling and it could take many, many years before any deliberation is made. And they're also very, very expensive to create this. So, it could be many, many millions of dollars, back then, even, in order to get more spectrum. Because there's only a finite amount of frequency in which we can transmit in because our phones can only handle a finite amount of frequencies. So, clear that that resource as we have more and more people, becomes more and more scarce. So, there's some bands, like for instance the WiFi bands, if we're talking about WiFi technology, that is unlicensed spectrum. But cellular is licensed. So, you need to buy a license, which would cost a lot of money, to be able to transmit in a cellular band. So, maybe the operators would have petitioned the FCC at this point, but in the mean time they needed to come up with another option. And the only other option was to try to figure out how they could fit more people in this same band. Instead of expanding and having more frequency to try to fit more people, rather than having 32 and try to have more like 64, or 128, or so on, keep going up. So, let's try to think this logically for a second. How'd you get more people to be able to use the network at the same time? So, suppose you're transmitting. This is you, you are sitting on your cellphone transmitting. Now, if someone like Charlie is this far away from you, Charlie may also be transmitting. And the assumption we are making here is that we are saying that each of them has to be on separate frequency channels. So, you might be on this channel and Charlie might be on this channel. But why do you have to be on separate channels? Well, as we said, it's because they would cause some sort of an interference with each other. But how pronounced is this really going to be, is this problem really going to be? It kind of depends on upon distance if you think about it. If you're speaking, wherever you are, I clearly can't hear from all the way over where I am because we're very far away from one another. And the reason that I can't hear is you is due to the fact that your signal attenuates, as it goes from, as it goes out farther and farther distance from you. It attenuates as it gets further away. So, in some distance around you say this circle right here, your phone signal will be very strong and pronounced. But then, as we go further and further away, like for instance, Ben over here, he won't hear your signal as strong because it will fade or it will attenuate as it gets over to Ben. And then, maybe by the time it get's to Charlie, it's so soft that Charlie can't even hear or Charlie's phone can't, wouldn't be able to hear your signal. And it wouldn't really cause any interference in that end. We call this concept attenuation. So, attenuation is really the decaying or the thinning away of a signal as it goes further away from its source. And we not only have attenuation over the air, we also have attenuation over wires as well. So, while attenuation sometimes looks upon as a bad quality because you may want to be able to get your signal to a far enough place without dealing with the fact that it's going to get smaller and smaller. Attenuation is actually necessary because if there wasn't this thing called attenuation we would all be able to hear each other sounds. And conversations at the same time, and that would drive everyone crazy.
