In which version of DOCSIS was an option introduced to increase the upstream spectrum frequency to 85 MHz?

The introduction of the option to increase the upstream spectrum frequency to 85 MHz occurred with DOCSIS 3.0. This version represented a significant improvement in the capabilities of the DOCSIS standard, enhancing both upstream and downstream data rates compared to its predecessors. The expansion of the upstream spectrum to 85 MHz allowed for higher upstream bandwidth, which facilitated services such as improved data upload speeds and better support for applications requiring higher return path capacity, like video conferencing and cloud services. DOCSIS 3.0 introduced channel bonding and other advancements, which together increased overall capacity and efficiency of cable networks.