4.2. Classes of Energy Limitation

4.2. Classes of Energy Limitation

Devices can be categorized based on the type and level of energy limitation they are subject to. The term "mains-powered" is often used to imply unlimited energy. The terms used in the present document and in [RFC6606] are as follows:

Name	Type of energy limitation
E0	Event energy-limited
E1	Period energy-limited
E2	Lifetime energy-limited
E9	No direct quantitative limitations to available energy

Table 2: Classes of Energy Limitation

E0: Event energy-limited. Nodes in this category have to limit the energy for a single event (such as a packet transmission) to make it possible to handle a number of such events on the net energy available from a period of energy harvesting.

E1: Period energy-limited. Nodes in this category can use a significant amount of energy in a single event (e.g., transmit a packet), but are limited in the sum of the energy available for a number of such events in a period of time.

E2: Lifetime energy-limited. Nodes in this category use their energy budget for the entire lifetime of the node. Typically, it is not practical to replace or recharge the energy for such a node.

E9: No direct quantitative limitations to available energy. Nodes in this category have no direct quantitative limitations to available energy. Energy is still limited, but at a higher level, such as by the limited budget of the owner of the node or by the availability of suitable electrical power infrastructure.