AT&T Taps OXiom To Cut Upgrade Costs

The urge for network efficiency, reliability and flexibility has driven broadband-service providers to make every dollar count, right down to the lowliest of nodes.

With that rising sense of urgency in mind, AT&T Broadband's OXiom — the next generation of the company's LightWire technology — has stepped up as the next golden child of deep-fiber management.

OXiom — a paraphrase of "axiom" based on the initials of its two inventors, Oleh Sniezko and Xiaolin Lu — is fiber-management technology designed to reduce the MSO's upgrade costs.

"The focus is on doing broadband architecture faster, better and cheaper, and we've been pleased with the outcome of LightWire," said AT&T Broadband executive vice president and CTO Greg Braden. "Now, there's another architecture beyond LightWire, and it's OXiom."

OXiom builds on LightWire's architectural advances and moves into the daisy-chain design of fiber nodes with less fiber management, making it easier and less costly to upgrade certain networks. The technology, which is now being deployed in Pittsburgh, is analog-based, but due to migrate to digital.

"There's lots of development work on LightWire and OXiom and [it's] being used in fiber extension there," said Braden. AT&T is considering at least two other markets for OXiom deployment this year.

OXiom is AT&T Broadband's most advanced fiber architecture. It uses mininodes to provide bandwidth to the end of a network, allowing for easier extension to expand plant into new builds.

"It's easily extendable plant at less cost and less fiber management," Braden said.

OXiom should save the MSO as much as LightWire, he said, but it's likely to be a few years before AT&T sees a return on its investment.

It costs about $40 more per home to put LightWire in place, compared to an HFC network. But on the life cycle-management side, costs are $11 per household, per year. Assuming a life span of 10 to 15 years, AT&T will see a return on its investment after four years.

"What we're doing different is paying closer attention to life-cycle costs," Braden said. "The purpose of OXiom isn't to get that $11 up to $15, however."


Despite OXiom's apparent cost-savings and maintenance-reduction advantages, the technology evidently isn't for everyone. Many cable operators have yet to embrace the LightWire or OXiom technologies because of the significant cost difference between aerial and underground deployment.

Both technologies are designed for aerial plants, which are more costly to deploy than underground plant. Because 70 percent of AT&T's plant is aerial, OXiom is more suited for the company's infrastructure and could be the architecture of choice in select markets.

In the meantime, AT&T is deploying OXiom's predecessor, LightWire, in Dallas and Miami, after it debuted in Salt Lake City to positive results.

"We saw some savings in LightWire's design around powering and the number of co- axial amps, and were pleased with the outcome," Braden said.

And there were other advantages. "We did estimates before we went to Salt Lake City and we learned that field engineers liked the balancing and sweeping of the network," said Lu, the vice president of AT&T's engineering group. "It was easy, and troubleshooting was too.

"We expected lots of data and that's why we rolled out LightWire in Dallas and Miami. Now, the architecture is being used in markets, not in trials."

Where OXiom will end up is contingent on data from its Pittsburgh deployment and the network peculiarities of various markets, which are crucial factors in determining its future use, according to Lu.

OXiom is rooted in what AT&T learned from LightWire and is continuing to evolve, with no next generation in sight.

"We have nothing on board after OXiom, so we'll be very interested in it," said Lu.

And both OXiom and LightWire are available to outside companies.

"We worked and developed them but have no proprietary claims to the architecture," Lu explained. "Moving forward, we'll use more OXiom than LightWire. It's happening quickly."

AT&T will use a combination of architectures in their upgrades and rebuilds: traditional HFC architecture, LightWire and OXiom, Braden noted. "Given the peculiar nature of each market, we'll apply either HFC, LightWire or OXiom as the variables dictate."


OXiom is based on the geographic locations of minifiber nodes, which are daisy-chained together with three fibers — one carrying downstream broadcast signals, another carrying the remaining downstream narrowcast signals and a third carrying upstream signals.

The technology's additional advantages come from its reduced fiber handling costs and its flexibility for future expansion and growth, AT&T said.

OXiom's advantage over LightWire is a deeper penetration of fiber to the end of a network. The cost savings of OXiom versus LightWire are modest at best, Braden admitted, but OXiom is a more advanced architecture that can provide easier network extensions and flexibility.

OXiom uses a physical-bus topology, which provides both shares and point-to-point lines on the network. By contrast, LightWire's architecture employs a physical-star architecture that only provides point-to-point lines. AT&T's OXiom study indicated that OXiom's cost is similar to that of a traditional HFC network — particularly in so-called greenfield situations — but with certain advantages. AT&T's OXiom study indicated that in greenfield situations especially, OXiom's cost is similar to that of a traditional HFC network, but with certain advantages.

"In greenfields you can deploy the technology at cost parity with HFC in 500-home nodes," said Aurora Networks president Tony Werner, who was a principal contributor to LightWire as AT&T Broadband's former CTO. "The trend is to fiber down to smaller, passive nodes and whether LightWire or OXiom, there are lots of ways to get there economically.

"As more operators look at network upgrades, LightWire and OXiom become very attractive and just too compelling regarding costs. Without a doubt, they are mainstream architectures for companies beyond AT&T."

Both LightWire and OXiom distribute everything to and from the headend over the fiber portion of the plant in time-division-multiplexed format, rather than the more costly amplitude-modulation process used in today's cable-distribution technology.

By delivering interactive, dedicated signals — as opposed to point-to-multipoint broadcast cable channels — in the digital baseband mode, AT&T can use off-the-shelf components to perform MAC functions at the mini-nodes and eliminate all in-line amplifiers between the node and end-users.

"We dream about things all the time," Braden said. "But OXiom really takes advantage of the commercially available stuff. We're anxious to take advantage of what OXiom and LightWire bring. They're sort of our natural hunger to improve our cost performance characteristics."

Where LightWire will end up in the evolution of OXiom isn't clear. But Braden insists the technology won't just go away.

"We look at OXiom as the technology for the next layer of cost structure," he said. "LightWire isn't antiquated, but we'll continue to see the evolution of architecture and systems as economies dictate.

"In the meantime, LightWire is still fully serviceable. It's step one, and OXiom is step two."

Experts say the trend is toward deeper fiber. With that would come an increased emphasis on trimming deployment and maintenance costs as cable operators and multiservice providers drive their networks deeper into neighborhoods and homes.

OXiom, which AT&T hopes will take the company to another level of cost savings and expandability, is now in the batter's box. Like its forerunner, LightWire, it must prove itself where it counts.