FT – Node placement(1)Two tier network architecture
Sensor Relay Nodes  Sink
Relay Nodes (RN)
Should be fault tolerant
Form the back bone of the WSN
There should be at least 2 disjoint path between two RN
Minimum RN will be chosen to keep the network k-connected
Each sensor connects to at least one RN
Sensor does only sensing, routing / data forwarding is done by RN  Increases Sensors operational life