Table 2.

Definitions of k-coverage: $\mathcal{A}=\{s_1,s_2,\dots ,s_n\}$ is the set of sensor nodes deployed in the ROI and “det. prob.” means “detection probability”.

k-Coverage by	Definition	det. prob. p Given by
k-expectation [18]	${\sum }_{s_i\in \mathcal{A}}p(u,s_i)\ge k$	Equation (4)
k-threshold [7]	${\prod }_{s_i\in {\mathcal{A}}^{\prime }}p(u,s_i)\ge p_{\mathrm{th}},\mathrm{for}\mathrm{some}{\mathcal{A}}^{\prime }\subseteq \mathcal{A}\mathrm{with}\left|{\mathcal{A}}^{\prime }\right|=k$	Equation (1)
k-layer (this paper)	see Definition 1	Equation (1)