By Dean Stoneback, Fred Slowik, ARRIS
It is estimated that approximately 1.5M miles of cable plant is now deployed in the United States. The majority of existing HFC networks have active 5-42 MHz reverse path in place. Much discussion has occurred during the past year relative to expanding reverse path network capacity on existing networks and how that expansion might proceed. Various ideas on the subject have included increasing the reverse pass band to 85 MHz, to 200 MHz, or even higher; adding a tri-split filter configuration with a second reverse path above 1GHz; relying upon node splitting and fiber deep migration to accomplish the goal; and incorporating a combination of solutions. Each approach has both technical and financial merits as well as disadvantages which need serious consideration.
To evaluate the costs of extending the upstream to 85 MHz or to 200 MHz (or greater) we will look at the issues involved in operating an HFC network upstream to those frequencies, including RF gain requirements, slope and AGC requirements and required laser performance. The cost of each of these components increases as the upstream bandwidth increases.