The presence of heterogeneous nodes (i.e., nodes with an enhanced energy capacity or communication capability) in a sensor network is known to increase network reliability and lifetime. but questions of where, how many, and what types of heterogeneous resources to deploy remain largely unexplored. We focus on energy and link heterogeneity in ad hoc sensor net- works and consider resource-aware MAC and routing protocols to utilize those resources. Using analysis, simulation, and real testbed measurements, in this seminars evaluate the impact of number and placement of heterogeneous resources on performance in net- works of different sizes and densities. prove that optimal deployment is very hard in general, also show that only a modest number of reliable, long-range back haul links and line- powered nodes are required to have a significant impact. Properly deployed, heterogeneity can triple the average delivery rate and provide a 5-fold increase in the lifetime (respectively) of a large battery-powered network of simple sensors.