By David M. Fellows, Continental Cablevision
Advanced modulation techniques, combined with protocols such as the MPEG 2 transport layer, have the ability to turn cable systems into broadband digital pipes to the home. However, a growing issue will be the bottleneck of data in the reverse direction, especially as the number of services supported over cable networks grows beyond Impulse Pay Per View and traditional status monitoring. Not only does the reverse path offer at best one-twentieth the bandwidth of the forward direction, but the noise and other impairments limit the aggressiveness of the modulation possible. Even though most applications still will use more bandwidth to the home than from it, the reverse path represents the most severe bottleneck in future systems. Only by careful utilization of this resource, and agreement on common protocols across services, will a cable network support all the services that will be required of it.