Does DOCSIS 2.0 have less rigid upstream performance requirements?
A. The upstream performance requirements in the DOCSIS 2.0 Radio Frequency Interface Specification are not less rigid than the requirements in DOCSIS 1.0 or 1.1. For maximum reliability and data throughput, cable operators still need to ensure that their networks comply with the recommended downstream and upstream radio frequency (RF) parameters in the DOCSIS Radio Frequency Interface Specification. The confusion about this arises from the fact that DOCSIS 2.0 provides for increased upstream throughput—up to a raw data rate of 30.72 Mbps. This is accomplished through the use of higher-order modulation formats, such as 64-QAM. In order for 64-QAM to work in the harsh upstream environment, either the upstream RF performance must be significantly improved, or the data transmission robustness must be improved. DOCSIS 2.0 includes provisions for improved data transmission robustness from several areas: • DOCSIS 2.0 supports a symbol (T)-spaced adaptive equalizer structure with 24 taps, comp
