Though telco fiber-to-node access networks are functionally similar to cable hybrid-fiber coax networks, the use of radio frequency modulation – essentially delivering traffic using the same techniques as over-the-air TV broadcasters or mobile radio and telephone – continues to be a salient difference.

 

Where global telcos use passive optical network and active optical network designs, some cable executives, though looking at PON, also are interested in Radio Frequency over Glass solutions that allow cable operators to leverage the rest of their RF investment if they migrate to fiber-to-home architectures, which most senior industry executives say is unnecessary.

 

But there seems to be less thinking that HFC actually is “the last upgrade” cable operators ever will need, which is what has been said ever since cable companies began to deploy HFC networks pulling fiber to 500-home nodes, with upgrades to 750 MHz operation (not “clock speed” as PC vendors use that term, nor a direct substitute for “megabits per second,” as other networks might be described).

 

Motorola (News - Alert), at least, thinks cable operators are moving towards RFoG, as it has added RFoG solutions through a strategic agreement with Alloptic. The agreement between Motorola and Alloptic (News - Alert) provides Motorola with exclusive rights to offer Alloptic’s RFoG solutions to leading cable operators worldwide.

 

The company also supports HFC and PON solutions, so the latest move covers all the bases. Still, the growing attention to RFoG suggests growing thinking that HFC is a transitional architecture, in the same way that digital subscriber line is a transition from all-copper access networks to FTTH. Cable executives would not say so in public, but that is starting to look more like a possibility.

 

RFoG is the same sort of innovation cable operators once used to deploy HFC. At the time HFC was conceived, there were only digital lasers available commercially, and cable operators told their suppliers they needed lasers capable of broadband modulation. Essentially, cable operators wanted to take the entire broadband output from their headends and input those signals directly into an optical transmitter, decoding the entire broadband signal a the other end of the glass.

 

Many well-informed technologists believed this could not be done, or could not be done at the distances, at the price, and at the bandwidths cable operators said they wanted. Obviously it was done. RFoG is the same sort of innovation, allowing continued use of all the other equipment and techniques while extending fiber all the way to the premises.