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CenterFuse Broadband Feasibility Report Overall Bandwidth of the Network. The electronics on an HFC network treat the network inside the wires as if it was a captive radio system. Originally the technology was used to transmit cable TV channels and wasn't used for broadband or other purposes. The historic network used different frequencies assigned to each "channel" of cable TV. Over the years as more cable TV channels were added by cable companies, the overall bandwidth of the HFC networks was expanded to accommodate the extra channels. HFC networks have ranged between 350 MHz (megahertz) of spectrum up to a gigabit of spectrum. Once broadband was added into the networks some networks grew even larger up to 1.2 GHz of bandwidth. The new DOCSIS 4.0 standard talks about increasing overall bandwidth even more. Still today, the networks in different cities are of different sizes in terms of overall bandwidth. A city served with a 950 MHz network is not likely to have as much bandwidth available as one that has been expanded to 1.2 GHz. Allocation of the Network to Cable TV. Going hand-on-hand with the overall size of the HFC network is the number of channels dedicated to delivering cable TV signal. Every channel dedicated to cable TV is one less channel that can be used for broadband. Historically there was once a channel of cable TV put into every channel slot of the cable bandwidth. But eventually, cable companies began to want to have a larger number of channels on the broadband network. This need exploded at the advent of high- definition programming when cable networks began broadcasting many of the channels in both standard definition and high-definition. Cable networks have also added a significant number of channels for sports networks and movie channels. Cable companies solved the dilemma of transmitting an increasingly greater number of channels through a conversion to digital technology. With a digital transition, cable companies could compress multiple channels into a frequency slot once used by only one channel. The most common compression scheme puts six channels into each slot, meaning that a network could put 360 channels where there used to be 60 channels. The number of channels varies between cable markets. Some cable providers elect to carry more channels of programming than others. Some major metropolitan areas have a lot more local channels that must be carried than other markets. It's not easy to compare the way that channels are used in different cable network. But the number of channels carried along with the total bandwidth of the local cable network is together the primary driver for the amount of bandwidth available for broadband. The Network Electronics. The technology that allows data to be delivered over an HFC system follows a standard called DOCSIS (Data Over Cable Interface Specification) that was created by CableLabs. Charter probably upgraded to the DOCSIS 3.0 standard around a decade ago. That standard allowed Charter to bond together enough channels to create broadband speeds as fast as perhaps 250 Mbps download (depending upon the other issues described above). In the last few years Charter upgraded most of their networks nationwide to a new standard, DOCSIS 3.1, that theoretically allows all of the channels on the network to be used for data and which could produce broadband speeds as fast as 8-10 Gbps if a network carried only broadband and had zero television channels. Since there are still a lot of TV channels on a cable network, most cable companies Page 70