UK-based cable broadband provider Virgin Media announced this morning that it has begun testing internet speeds of up to 1.5Gbps in London, using four startups from the "Silicon Roundabout" hub as lucky guinea pigs.
The 1.5Gbps trial, Virgin Media claims, uses the same cable infrastructure and technology that powers the broadband service for millions of households in the UK, and is even faster than the projected 1Gbps speed that South Korean ISPs are proposing to implement in 2012. Earlier this year, ARRIS announced that it is working with SK broadband to deliver speeds of up to 800Mbps by combining 16 Downstream channels.
The company has not been forthcoming to provide more details regarding how this was achieved; we know that the upload speed reaches 150Mbps (more than VM's current top of the range download speed) and that it uses DOCSIS 3.0 which allows the bonding of multiple downstream and upstream channels together.
Back in December 2008, Virgin Media introduced a new 50Mbps modem that allowed four-channel bonding, which in theory would allow speeds of up to 200Mbps to be reached.
As we noted then, combining eight downstream channels using EuroDOCSIS would allow Virgin Media to reach 445Mbps with upstream throughput reaching 108Mbps.
This could mean that four modems were combined to reach 1.78Gbps, and such a solution actually exists courtesy of a little known service provider called Sharedband which provides kit (on the client side) that allows up to four ADSL lines to be bonded together, albeit at a price. Sharedband is already collaborating with Virgin Media's main competitor, BT, and may well have teamed up with VM on this project.
The cable company hasn't confirmed when it will start rolling out the new service and whether it will limit it for the time being to business users. However, given that it has already started tests for 200Mbps and is already selling a 100Mbps service while its rivals are barely off the 40Mbps mark, it's safe to assume that time in on Virgin Media's side.