This chapter gives our measures of
connectivity and fault-tolerance of two-dimensional
-covered wireless sensor networks. The latter measures are more realistic than the former as they impose a restriction on the subsets of sensors that can fail at the same time. Precisely, conditional measures take into consideration the inherent properties of
-covered wireless sensor networks, such as high sensor density and sensor heterogeneity. In particular, the neighbour set of a sensor is defined as a
forbidden faulty set
, and hence cannot fail at the same time. This concept defines the new measure of connectivity, called
, which seems to be more realistic.