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Television on The Internet – How much Bandwidth is Needed? Where?

02 апреля 2007
There’s no question about it, watching live video over an Internet connection is not something you want to on a dialup connection. On the other hand, if you receive TV today either over the air (the old way), from a satellite dish, or through a cable, you already have MORE bandwidth coming into your house than you’ll need for watching TV on the Internet. So why is everyone gonna need a fiber connection to his or her home to be able to participate in the future? And how come there’s a bandwidth crisis coming?

Short answers: Even though we all do need a lot more bandwidth into our homes than we have on a dialup connection and we’ll soon outgrow basic DSL, we DON’T all need fiber connections. If we all shift to watching TV on the Internet, the total bandwidth (Internet and other) required INTO our homes will decrease and the load on the Internet backbone and the regional distribution portions of the Internet will be – well – interesting. It’s a separate subject for a separate post but we most of us need or will soon need lots more bandwidth OUT of our houses for sending stuff.

Just a quick refresher on how TV signal distribution works today. In most places, there are a number of local channels still broadcast over the air from high towers. Some of these include high definition programming. All of these channels are received by your antenna (if you still have one) all the time. All of these channels fit in the thin wire which runs from the antenna into the back of your TV. Obviously lots of bandwidth there.

If you have cable, all 200 or so channels including the ones you don’t subscribe to are delivered to your set-top box. Same thing if your “cable” runs to a satellite dish. Whatever channel you’ve decided to watch (assuming you’ve subscribed to it) is delivered from the set-top box to the TV. That (and the vested interest of your satellite or cable provider) is why you “need” one set-top box for each TV capable of watching different channels from the other TVs (unless you’re a TV hacker).

Now let’s fast forward to Internet TV. You can watch any show you want any time you want although you still may have to pay for some of these. How many shows are going to be watched at once in your house? Two? Four? Not 200, right? So you need LESS bandwidth for incoming shows than you have with cable or satellite today. The problem – if there’s a problem – is that you need that bandwidth in your Internet connection and it may not be there today.

But wait, you say, my Internet connection already comes into my house on my cable. And so do all 200 channels. So I’ve already got enough bandwidth. You’re right; you do. It just has to be rearranged a little. And remember, you’re not even gonna need to bring in 200 channels at once, just the ones you’re actually watching. Maybe you should get a rebate.

Point is you don’t need fiber coming into your house to get all the TV content you can watch – even high def. Today’s coaxial cable connections have more than enough bandwidth. Today’s DSL, however, does not although it is possible that successor technologies will be able to deliver enough bandwidth for Internet TV over telephone wires to people VERY close to the telephone office (now you know why, in general, it’s phone companies and not cable companies who are installing fiber). Fixed wireless Internet access CAN also deliver enough Internet capacity for multiple TV shows and high definition (which needs more bandwidth) although it usually doesn’t today.

The chart below is from a Swedish study. “Twisted pair” is what is used to deliver today’s DSL. In all cases, they are talking about what can be achieved with the various delivery technologies – almost always more than is being done today.

Fiber is a great way to bring bandwidth into a house, bit it’s not the only way to meet today’s or even tomorrow’s need for last mile connectivity. However, fiber to the community is becoming increasingly essential; it’s needed for many more reasons than just allowing TV to migrate to the Internet. Although we’ve seen that Internet TV decreases the total need for bandwidth coming into the house, it will create a huge new load everywhere but in the last mile.

Think of the cable network as it enters your town but consider just the entertainment on it and forget that it’s also being used for Internet access. No matter how many homes are connected, there only has to be bandwidth for 200 channels. Everybody has to watch the same show exactly when it’s delivered (except for those people who use DVRs to record the shows and replay them later). I’m ignoring the pitiful amount of video on demand offered on today’s cable systems.

But let’s fast forward to Internet TV. Now any of us can watch whatever we want to watch whenever we want to watch it. Now how much entertainment bandwidth do we need coming into town? How many different shows are being watched in the whole community? Even when two families are watching the same show, unless it’s live, they’re probably not watching it at the same time so many versions of the same show will be delivered.

More bandwidth isn’t the only way to allow more choice; I’ll talk about some others in future posts. But more bandwidth – in most cases best delivered on fiber – must be provided between communities before full Internet TV is a reality.



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