Posts by abz »

There is so much talk about Broadband these days, but few people know what it actually means.

In technical terms, Broadband refers to a telecommunication medium that provides multiple channels of data of a single communication medium, typically using some form of frequency of wave division multiplexing.

What this means is that Broadband refers to any technology which can densely pack information and thereby allow a higher rate of transfer. This is why Broadband is always touted as the new, faster generation of Internet access services.

This is not the whole truth however. See, this faster technology only refers to the last mile, in other words, the link between you and your ISP’s nearest branch or aggregation point.

While this faster technology provides you with a faster link to the ISP, your ISP still needs to buy expensive national and International bandwidth.

So how does your ISP manage to give you more bang for their buck? Simple! They over subscribe!

Not making sense? How about an analogy.

When you buy insurance, your service provider (in this case the insurance company), takes your money and puts it in a big pool. They know that not all cars get stolen, houses burn down, etc. so they can pay out less than they are collecting from their subscribers even though you could potentially claim more than you’ve actually paid.

Broadband (in this case referring to your over subscribed bandwidth) is essentially the same thing. ISPs buy bandwidth in a big pool, give each of their customers a small pool which collectively adds up to much more than they actually buy themselves, but they know this works because only a small portion of their subscribers will use that bandwidth at any given time.

Let me demonstrate with an example. Remember those Vodacom HSDPA advertisements that claim up to 3.6 mbit/s? Well, that’s not a lie! What they don’t tell you is that the advertised speed is for your connection to the nearest cellular tower. Every single customer connecting to that particular tower shares a single 2 mbit/s connection to the Internet. Let’s say there’s 10 customers connecting to that tower sharing the same connection. Should they browse the Internet simultaneously, they will get 2/(3.6*10) or 5.5% of the advertised bandwidth.

This however is not what the marketing department of your ISP would like you to believe. No, they define Broadband as FAST!!! - with those three exclamation marks, capital letters and bold type face.

Not that this is a complete lie.

Broadband does refer to new faster technologies which promise better speeds, but always keep in mind that your service is over subscribed. The amount of over subscription determines how likely your chances are to actually get the speeds you are promised in that advertisement on television.

Over and above the over subscription of bandwidth, your connection will always be limited by the type of technology used. For ADSL this means the quality of your copper telephone line, for Wireless it means coverage, interference, and a host of other factors.