Genesis Technical Systems of Canada has announced an improvement to an existing technology that might breathe some life into rural copper networks. The technology is called DSL rings. The technology is not entirely new and I can recall seeing it being discussed fifteen years ago, but the company has added a twist that improves on the concept.
DSL rings are essentially shared DSL. Currently deployed DSL technology can bond together two pairs of copper and in real-life networks can get as much as 50 Mbps speeds. Under current DSL architecture, the bonded pairs are dedicated to a single home/business. DSL rings instead allows for the bonding of multiple pairs of copper that are then shared among multiple homes. In that bonding process there is a little less new bandwidth available from each pair added, so there is a natural limit on the number of copper pairs that can be bonded.
From the neighborhood device in a pedestal, the “ring” is created by using one copper pair “into” each home and one copper pair “out”. This architecture is looped repetitively through all of the homes in the ‘ring’ so that they are on one continuous copper ‘ring’. For example, in a neighborhood where there are ten homes that can currently each get 10 Mbps using standard DSL, this technology might create a 80 Mbps pipe that would be shared by all ten homes. But at peak times when all of the homes are using a lot of bandwidth this might not be much faster than today. But by sharing all of the bandwidth with everybody, customers would have access to more bandwidth when the network isn’t busy. A single customer would have access to the whole 80 Mbps pipe. The technology is an improvement on traditional DSL – it uses the same bandwidth-sharing concept as fiber and cable TV nodes where customers in neighborhoods share bandwidth rather than each getting a separate bandwidth pipe.
The current DSL ring technology wouldn’t do anything useful for today’s rural DSL, since there is not a lot of benefit in bonding together slow connections that are only at 1 or 2 Mbps. But as CAF II is implemented by the big telcos and as faster DSL is built into the rural areas, this idea might make sense.
Genesis Technical Systems’ new twist is that they can use the DSL ring base units as a DSL regeneration site, meaning it can not only serve the nearby homes, but the unit can send out bandwidth to the next DSL ring and start a new 2 – 3 mile delivery circle around the next ring in the chain.
The big drawback to that idea is that the second chain is going to be limited to the amount of bandwidth that can be sent to it up the copper, and so it won’t have nearly as much available bandwidth as a DSL ring that is fed by fiber. I see that as the big limiting factor. But this might allow for a network with one or two DSL ring ‘hops’ that can reach further out into the rural area with faster DSL, with each subsequent ring getting significantly smaller bandwidth.
The ideal configuration would be to feed each DSL ring with fiber. But even without considering the cost of building new fiber the technology is not cheap, in the range of $600 to $800 per home added.
There will be other issues to deal with in the rural areas. Most copper networks are ‘loaded’ meaning that there are equalizers to maximize voice quality and this loading would have to be deactivated to use the DSL technology. In some areas, there might not be enough spare copper pairs to make the ring. These days we all assume that most homes have abandoned landlines for cellphones, but in rural areas where the cellular coverage is bad there are still pockets of homes where most have landlines. But copper pairs could be freed by converting analog voice to VoIP.
In looking at the technology, I see the most promising use of it in rural towns, like county seats. Neighborhood rings could be created that would upgrade DSL to compete with most current small town cable modem systems. Where customers might today be buying DSL that has speeds up to 6 Mbps or 12 Mbps they might be able to get speeds up to 50 Mbps or 100 Mbps. But the big caveat on this would be that these rings would slow down during the busiest evening hours similar to older cable TV networks. Still, it would be a major DSL upgrade.
It’s an interesting technology, but at best it’s the last gasp for an old copper network. If this technology is used to move DSLAMs closer to rural homes they are going to get a lot more bandwidth than they get today. It looks like in the ideal situation the technology would let customers burst faster than the FCC’s broadband definition of 25 Mbps. But to some degree this extra speed is illusory – during peak times the DSL would probably be significantly slower. My guess is that if one of the big telcos adopt the technology they will claim the burst speeds in reporting to the FCC and not the achieved speeds at the busy hours of the day. But customers would quickly figure out the difference.