By Daniel Howard, Enunciant, LLC; Chris Day, Analog Devices; Kevin Gantt, CommScope; John Holobinko, Cisco; Rob Howald & Dan Marut, Comcast; Dick Kirsche, ConsultKirsche; Todd Loeffelholz, Alpha; Kathleen Miles, PG&E; Rene Spee, Coppervale; Dean Stoneback, SCTE•ISBE; John Ulm, Arris; Lamar West & Dan Whitehouse, Hitachi Consulting
The cable outside plant consumes the majority of power of the overall network. Power is consumed not only by the active devices (optical nodes, amplifiers, Wi-Fi hot spots, LoRa gateways, micro cells, cell backhaul, 5G, etc.) but also by the process of moving the power through the outside plant to reach these devices and the associated Joule heating (I2R) losses in the cabling.
Changes underway in the network architecture and increases in the sophistication and functionality of the active devices are predicted to cause an increase in the power required. Remote physical (PHY) and remote media access control (MAC) and PHY are predicted to increase the power dissipation at the locations of conventional optical nodes. Amplifiers with higher gain and higher radio frequency (RF)bandwidth and the resulting linearity demands may also increase the required dissipation at these locations, however this increase may be offset by gallium nitride technology and new energy efficiency measures. Finally, the addition of new active devices such as Wi-Fi hot spots, micro-cells, and LoRa gateway devices will add new powering burdens to the outside plant (OSP).
The present network architecture transports the electrical power for these active devices through existing coaxial cable or cable that is specifically dedicated to transmission of electrical power. The coaxial cable exhibits a significant electrical resistance at the frequencies used for electrical power, typically 60 Hz or 50 Hz. The resistance of the coaxial cable at powering frequencies is virtually identical to the resistance at DC and is therefore typically referred to as the coaxial direct current (DC) loop resistance. The DC loop resistance can result in dissipation of significant amounts of electrical power in the coaxial cable itself as the electrical power is transported through the OSP to active devices.
These sources of power utilization in the OSP will be enumerated in this document. Several expected changes that will affect the power utilization are then reviewed. Finally, energy conservation measures to reduce or minimize the power required to operate the outside plant are explored. The technology trends and recommendations for conservation measures are part of an overall road map (see Figure 1) of the SCTE•ISBE Access Network Efficiency (ANE) working group within the Energy Management Subcommittee (EMS) of the SCTE•ISBE Standards program. This road map exists to address energy consumption and conservation in the access or “last mile” portion of modern cable networks.