Friday, February 25, 2005

Copper That Thinks It's Fiber

I was shocked when reading "Om Malik on Broadband" to see an announcement about a new chipset that offers 100 Mbps upload and download speeds on copper telephone wire, of all things. Is this DslMAX, the landline equivalent of WiMAX?

Ikanos Communications, the company that issued the press release on the new chipset, isn't calling its product DSL anything. It goes by the name "FX 100100." The FX stands for fiber extension. At first I thought the 100100 might be a binary 36, but on closer inspection it simply indicates a symmetric 100 Mbps upstream and 100 Mbps downstream data rate.

Fiber extension is the real goal of the Ikanos chipset. The range at this speed is more like a few hundred feet rather than a few miles. The idea is to run fiber optic service to the neighborhood or curb, and then deliver service to the commercial building, apartment building, or single family home using Ma Bell's good old copper pairs. Why such a hybrid arrangement? It avoids the messy and expensive process of trenching fiber for a passive optical network to each and every dwelling. Getting copper to run at fiber speeds has even greater leverage in downtown areas where it can be cost prohibitive or even impossible to go tearing up streets to reach every building.

So how do they do that? I keep hearing that copper pairs are on the verge of being reclaimed by nature after a hundred years in the ground. The only sensible transmission medium for the future is fiber. Right? Well that would be true if we were starting from scratch. Everyone would be installing bundles of glass fibers for data, telephone, television, and everything else. You only need copper to bring in power. In a situation where you are trying to provide new high speed services to an already built-up infrastructure, the lure of using all that in-place copper wiring is just too compelling to ignore.

I'm starting to think that there is something of a "Moore's Law" for copper. Gordon Moore of Intel postulated 40 years ago that processor speed would double every 18 months without knowing exactly what breakthroughs would be needed to keep going at that rate. Yet, it has happened. Copper telephone wire was supposed to be tapped out with 56K dial-up modems. Yet, ISDN and the various flavors of DSL keep pushing the bandwidth limit up and up. Even in the office, copper twisted pair keeps fending off the advance of fiber with speeds up to 1 Gbps and experimentally up to 10 Gbps.

The magic that Ikanos Communications is using is an intelligent set of integrated circuits that combines discrete multitone modulation (DMT), a 150 Mips (millions of instructions per second) microprocessor, plus analog and line driver interfaces. The system is smart enough to measure the characteristics of the particular phone line when it powers-up. Then it cleverly transmits more bits in frequency bands that have less noise, and fewer in bands affected by interference or bridged line taps. The performance comes from the fine tuning required to flow as many bits through that copper straw as you might just dump down a fiber optic fire hose.

For copper based services, T1 Rex can help you get the lowest prices on available business grade DSL and T-carrier services. If you need fiber bandwidth up to Gigabit Ethernet or OC192 capabilities, try our GigaPackets service.

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