power game

AS RBOCS GO FORWARD WITH FIBER extension plans — a move to provide the bandwidth necessary to deliver the triple play — the configuration of the outside plant is changing. Amid the evolution, how these fiber networks are powered has become a top economic consideration.

One issue is who pays for the power. Verizon Communications Inc. is building out an FTTP network, dubbed FiOS, based on PON. PON does not require powered remote terminals in the field between the CO and the customer premises. Some believe eliminating that power requirement significantly lowers costs.

However, PON architectures still require active electronics at the home, notes Kermit Ross, founder of research firm Millenium Marketing. “The telecom companies make a lot of noise about an all-passive network with no batteries or active electronics to maintain,” he says. “But there is still a power cord and batteries plugged into every home. Since the ’30s, telephone companies have supplied power and kept a DC generator to keep the batteries charged up so the phone still works in a blackout, for emergencies. Now, this all goes away. This is an enormous degradation in the service that companies are providing their subscribers.”

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FTTN, the deep-fiber approach favored by BellSouth Corp. and SBC Communications Inc., has its own power peccadillos. Namely, it requires too much power. FTTN typically brings fiber to within about 3,500 feet of the home, then uses copper from there. At that range, companies like SBC say DSL can deliver the appropriate bandwidth for the triple play. To extend the network, companies are putting remote DSLAMs into crossconnect boxes, most of which are within the 3,500-foot range.

“SBC alone has 80,000 new active nodes in the network, and across all the practitioners of FTTN we’re talking about tens of thousands of new active electronics,” says Ross. “In some cases, companies are doubling the number of remote sites in the network, so power becomes a real issue.”

The ability to manage the electronics and to maintain the integrity of the CO environment out in the field is another issue in FTTN deployments. “Everything here is about moving the electronics toward the subscriber,” says Dennis DelCampo, vice president of business development and marketing at network power company Emerson Energy Systems.

Because fiber can’t carry energy, but does carry the signal, and vice versa for twisted pair, it’s necessary to convert the signal to an electrical form at the point where fiber meets copper. To effect that conversion, a phone company usually needs a 48-volt DC source at the CO, with battery backup. When the optical/electrical conversion is moved to the outside plant, companies must account for the longer fiber distances and more power-hungry gear, so the voltage is stepped up to go the distance.

“The question becomes, ‘where do you perform the optical/electrical conversion?’ And you need not only power for the equipment, but also backup power and protection for optics, not to mention thermal protection in the cabinet,” says DelCampo.

To address such maintenance concerns, Argus Technologies, maker of DC power products for telecom networks, has released the Tempest Te17, a lightweight yet rugged enclosure with an optional sub-base for cable management or batteries, and environmental control choices including air conditioning, insulation and heating, as well as battery heater pads to meet specific environmental requirements.

To fight the space limitations, maintenance costs and voltage concerns that make it hard to locate power equipment and batteries in remote cabinets, line power systems send power from the CO across unused copper telephone lines to the cabinet. These systems reduce deployment costs by reusing existing network cabling and by removing the need for AC utility service and batteries in each remote node.

“Triple-play services and IP-based television is one of the biggest changes in the telecom network in our generation,” says Greg Fasullo, co-founder and vice president of sales and marketing at Valere Power, which this year announced its Line Power Solutions family for extending battery backup power for FTTx deployments.

Whether power is achieved by installing a power meter and line at each node, creating new central power nodes for power feeds from the CO, or some other approach, “some profound changes are occurring in the topology of the network,” says Ross.