* How much bandwidth is enough?
We spend a lot of time speaking with service providers and with access equipment vendors. In the course of these conversations, we hear a lot of different and disparate ideas about how much bandwidth is “enough” for the consumer.
Most carriers and just about all the equipment vendors agree that today’s 1M bit/sec service is not sufficient. But try to get a firm declaration of how much a telco should be providing, and the answers you hear depend upon the technology which someone has wedded themselves to. Typically, we hear ranges between 10M bit/sec and 20M bit/sec, with some higher numbers coming from fiber proponents.
We like to break down bandwidth requirements not into megabits per second, but rather into applications. Take triple play, for example. Most U.S. triple play deployments use ADSL facilities, and with about 7M bit/sec or 8M bit/sec downstream in the best conditions (short loops, excellent copper, etc.) these triple play deployments can provide two simultaneous standard definition TV channels – at least they can if a fairly hefty dose of compression is applied to the TV signals. This scenario leaves almost no bandwidth “left over” for VoIP and other IP applications – the other two legs of the triple play.
In a scenario like this, the roughly doubling of bandwidth provided by ADSL2+ looks pretty handy. And, in fact, it is – with 15M bit/sec or so downstream, you can offer 3 simultaneous standard-def TV channels, plus have some bandwidth left over to throw at all the IP applications that users might require.
Bump up the bandwidth a little bit more – to the 20M bit/sec or so that many folks envision as a good mid-term future service – and you can even shoehorn in a single channel of HDTV, if you use an advanced codec like MPEG-4 or Windows Media Player 9.
Sounds good so far, right? Well, this is where we think the logic falls apart. See, we’ve just been crossing the final “t’s” and dotting the final “i’s” for a new book – HDTV for Dummies – and in the process we’ve been living, breathing, and occasionally eating HDTV. We mention this because if you’ve not been paying attention, you may have missed the fact that HDTVs have become dirt cheap in the past six months or so. Really big projection HDTV systems, suitable for a home theater, are dropping well beneath the $2,000 mark, and big tube TVs are well below $1,000.
The important development, however, is the new generation of small HDTVs that are hitting the market. Skinny LCD HDTVs are real hits on the market place, and we’ve started to see small tube-based HDTVs that are bringing the lowest HDTV prices yet – under $700 retail. As a result, we’ve reached the point in terms of price and form factor where the HDTV in the family room or home theater is about to be joined by a second (or third!) HDTV in the kitchen or master bedroom.
This prospect boosts the bandwidth requirements of a residential customer through the roof. Remember that HDTV channels take approximately 19M bit/sec or 20M bit/sec a piece (when using MPEG-2 compression), and even with newer codecs, each HDTV channel will probably take up something in the range 10M bit/sec of downstream bandwidth. So even in the best case scenario a triple play service can easily exceed the 20M bit/sec that some carriers think will be “enough.”
We’ve focused on HDTV here because it’s such an obvious bandwidth eater. In future columns we’ll talk about other not-so-futuristic applications that can do their own bandwidth damage – and in doing so make the case for truly high-speed last mile connections.
