Power savings and MoCA

Table 2 shows an example of the potential savings in the yearly energy consumption between a MoCA 1.x Node and a MoCA 2.0 Node, assuming, for example, that MoCA 1.x always consumes 2W and MoCA 2.0 consumes 4W in the Active state, 1W in the Idle state, and 0.3W in the Standby/Sleep state. The MoCA 1.x Node is assumed to always be in the active position and the MoCA 2.0 Node is assumed to be in one of the low power states for 17 hours each day.

Power Savings beyond MoCA
Since the MoCA 1.x specification does not support low power states, implementations of MoCA 1.x Nodes are not expected to support the hardware handshake required between the Node and the rest of the system to allow a smooth transition of the rest of the system into and out of low power states. An example of such required handshake is an interrupt mechanism from the MoCA Node to the host to Wake-Up the host to receive and process a packet arriving from the MoCA network.

The MoCA 2.0 specification, on the other hand, put an emphasis on providing all the mechanisms required for both the Nodes and the rest of the system to go into low power states and only Wake-Up when necessary. All MoCA 2.0 implementations will have full support of multiple power states and will include the required software interface to allow full control of the host on the power states of the Node. These implementations will also have the required handshakes for supporting the smooth transitions of the rest of the system into and out of low power states.

In STBs the consumption of the MoCA subsystem is a small part of the total power consumption. Using MoCA 2.0 will allow a significant reduction in the total energy consumption of the STB by allowing both the MoCA subsystem and the rest of the system to go into low power states smoothly and without interruption to the MoCA network.

Table 3 shows an example of the potential energy savings of the new generation STBs which are based on MoCA 2.0 implementations relative to the current implementations. The power consumption of the STB is assumed to be 30W when it is fully functional (Active state) and 0.5W when in a low power state (Standby or Sleep).

Summary
This paper points out the lack of power saving features in MoCA 1.0 and 1.1, and presents the extensive support of MoCA 2.0 of such features in the form of four power states ranging from Active to Sleep, a Wake on MoCA feature, and a software interface to a PMS. This paper also describes the four power states and how the MoCA Node interacts with the MoCA network and with the PMS when transitioning between the different power states. The paper concludes by showing that the mechanism provided by MoCA 2.0 for transitioning between the different power states can enable implementations which significantly reduce the overall energy consumption of the entire system.

Appendix
The United States Department of Energy has recently started an initiative to regulate the maximum allowed annual energy consumption of STBs and networking equipment.¹ This effort is separate from the well known ENERG Y STAR program² administered by the Environmental Protection Agency (while this effort is optional, most operators and OEMs participate in the program, which implements increasingly stringent requirements on a regular basis). The Energy Policy and Conservation Act allows for the regulation of devices that have average annual per-household energy use exceeding 100kWh and STBs will almost certainly qualify. It is possible that regulation will be completed by Q3 2012 with an effective date three years later (based on date of manufacture of finished product).

The California Energy Commission has begun its own effort around regulation of STB power and is in the early information gathering process.³ The European Commission also has an active program to encourage industry self-regulation of STB energy consumption.⁴

References
1 http://www.regulations.gov/#!docketDetail;dct=FR+PR+N+O+SR+PS;rpp=10;po=0;D=EERE-2010-BT-DET-0040
2 http://www.energystar.gov/index.cfm?fuseaction=find_a_product.showProductGroup&pgw_code=ST
3 http://www.energy.ca.gov/appliances/2011rulemaking/index.html
4 http://re.jrc.ec.europa.eu/energyefficiency/html/standby_initiative_main.htm