Satellite and Backbone Internet Services

It shouldn't be a surprise to hear that our preferred form of broadband is broadband-via-satellite.

Today and for the foreseeable future satellite remains the only technology that can deliver broadband connectivity to any/every location in a chosen country or region. This is particularly important for corporate or digital media networks where you have to deliver to 100% of (say) the stores of a supermarket chain, not just the x% of stores that can be reached by ADSL/3G/2.5G/DTT/cable. Satellite benefits from broad geographical coverage such as the whole of Europe or the whole of north America, and provides an exceptionally broad bandwidth pipe compared to the other mediums described above. For example, a 40cm Sky Digital antenna in the UK can receive multiple 40MBit/s channels up to a total capacity of around 3,200 MBit/s

Broadband-via-satellite products generally provide an asymmetric connection to the internet backbone e.g. 2MBit/s outbound from the backbone to the user and a 512kBit/s return path from the user to the backbone. This reflects the normal usage pattern of downloading more information from the internet than a user sends. The connection to the internet backbone might be either on the US east coast (with the service on a trans-Atlantic satellite) or here in Europe.

A typical service configuration will use:

• A single outbound carrier from the backbone to the user with IP-over-DVB encapsulation at a composite data rate of upto 40MBit/s. This would be partitioned into a number of virtual channels at 512kBit/s, 1MBit/s, 2MBit/s etc.
• Multiple return path channels from the user to the backbone with an appropriate multiple access scheme (TDMA, CDMA, Aloha, etc)

Users subscribe to a service at a particular data rate (e.g. 2MBit/s outbound and 512kBit/s return path) and are assigned to an appropriate outbound and return path channel. These channels will be shared by a number of other users, typically 20, 40 or 60 per channel. This sounds like significant contention, but it is so much better than contention at the IP access port (which might be as high as 1,000:1) that the satellite path is never the dimensioning part of the link.

Different products offer a wide range of outbound to return path bandwidth ratios (from 3:1 to 20:1) and channel sharing ratios (from 1:1 to 60:1)

Broadband-via satellite is generally pitched at a market above ADSL and below a leased-line solution. Over recent months several service providers in Europe have announced their broadband-via-satellite products, but some have withdrawn from the market before launching a service and several others as yet have nothing to offer! Separating what's real from what's hype is no small task in this market, and we have been following this closely for our clients.