Hybrid Fiber Coaxial Networks

Fiber dramatically cuts the number of amplifiers needed in the distribution and transport networks. The degree to which fiber is installed varies from provider to provider. Some providers have opted to go entirely fiber into the subscriber premises. Fiber transports the signal using either laser or light emitting diode (LED) technologies depending on the type being deployed.

Fiber has a number of benefits over traditional cable. Fiber is thin and lightweight, able to cover longer distances with virtually no loss of signal or noise, and is immune to outside sources of electromagnetic interference. Because the number of amplifiers is reduced, there is some monetary benefit associated with support and equipment costs. There is some discussion as to which is easier to handle, cable or fiber. Essentially, that discussion comes down to preference. Cable tends to be rigid and sturdy whereas fiber is thin and somewhat pliable, requiring some advanced skills and care to properly terminate.

Fiber trunks have been used to replace trunk cables in the architecture. These carry downstream traffic from the headend to the neighborhood node where the signal is converted from light to electrical and forwarded on to the subscriber via copper coaxial cable at signal strength greater than 50 decibels (dBm). A decibel is a unit of measure for expressing ratios between two quantities. The prefix "deci-" follows the International System of Units (SI) unit designation, meaning 1/10, and is always lowercase. To further confuse the issue, the decibel merely follows the SI naming convention; it is not an SI unit. The "bel" portion of the word is derived from Alexander Graham Bell's name; therefore, it is capitalized. When discussing absolute power levels, such as the signal strength on a cable network when the signal reaches the subscriber, the power is given in relation to milliwatts. This is expressed as dBm.

The movement of the cable system infrastructure to the HFC network architecture is essentially the catalyst that allowed for more advanced services to be offered. Initially, this was limited to data over cable but has evolved significantly and will continue to do so. DOCSIS 3.0 and Cisco's Wideband channel bonding technology will push the services and applications offerings forward at an unimaginable pace. This, coupled with the integrated services and applications afforded to the teleworker by Service-Oriented Network Architecture (SONA), will reinvent the way in which we work, live, play, and learn. In the same manner that SONA provides the framework for enterprise evolution to an Intelligent Information Network (IIN), the service provider market has an IP-Next Generation Network (IP-NGN) architecture providing a path to a similar destination. Once both the enterprise and the service providers begin to reach the true IIN state, the goal of "one experience regardless of locale or access device" will evolve to encompass both networks. One user, any service, anywhere will be a realistic expectation.

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