Cox has launched its DOCSIS 3.0-based broadband service in Northern Virginia. The service, which offers 50-Megabit-per-second (Mbps) downloads and 5 Mbps uploads and comes with PowerBoost, will cost $139.99 per month. In comparison, Cablevision is charging $100 a month for 101 Mbps service in parts of New York. Cox is among a growing list of cable broadband providers that are using DOCSIS 3.0 to compete with Verizon’s FiOS assault. Like most of its peers, Cox is selectively rolling out higher speeds in regions where it has competiton — for instance, in Lafayette, La., where it faces challenges from a municipal-backed fiber effort. Among the big cable companies, Time Warner Cable is limping in its DOCSIS 3.0 efforts.