The network layer takes care of routing the data supplied by the transport layer.
The network layer of a sensor network is usually designed according to the following principles:
• Power efficiency is always an important consideration.
• Sensor networks are mostly data-centric.
• Data aggregation is useful only when it does not hinder the collaborative effort of the sensor nodes.
• An ideal sensor network has attribute-based addressing and location awareness. Energy-efficient routes can be found based on the available power in the nodes or energy required for transmission in the links along the routes.
An energy efficient route is selected by one of the following approaches:
• The maximum power available (PA) route is the route that has maximum total PA.
• The minimum energy (ME) route is the route that consumes minimum energy to transmit the data packets between the sink and sensor nodes.
• The minimum hop (MH) route is the route that makes the minimum hop to reach the sink.
• The minimum PA node route is the route along which the minimum PA is larger than the minimum PAs of the other routes.
An overview of the network layer protocols proposed for the sensor networks is given in Table.
These protocols need to address higher topology changes and higher scalability.